Slide 1 This lecture is the third part of the parasitic protozoa. It represents the second part of the apicomplexan parasites and we will cover malaria and . As you will see Lecture 9: Emerging Parasitic this lecture is quite long and heavy on malaria. And that Protozoa pt. 2 (Apicomplexans-2: Malaria, Babesia) is because malaria is such a huge global health problem. Presented by Sharad Malavade, MD, MPH

HSC4933 1 Emerging Infectious Diseases

Slide 2 These are the readings for the lecture. The tables are Readings-Lecture 9 significant and should be studied well. • Ch.8 (p. 183 [table 8.3], pp. 187- 194, special attention to tables) • Ch. 11 (pp. 310-15) • Ch. 14 (pp. 412, 422, 425)

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Slide 3 These are some web links for you to get some Monsters Inside Me background information • Malaria (Plasmodium spp., Apicomplexan): Background: http://www.cdc.gov/malaria/about/index.html Video: http://www.animalplanet.com/tv-shows/monsters- inside-me/videos/malaria-parasite.htm (Babesia spp., Apicomplexan): Background: http://www.cdc.gov/parasites/babesiosis/ Video: http://animal.discovery.com/videos/monsters-inside-me- babesiosis.html

HSC4933. Emerging Infectious Diseases 3 Slide 4 These are the learning objectives of the lecture. Most of Learning Objectives the lecture covers malaria. Malaria is a global health • Understand the enormous impact malaria has on global health • Know the various species of Plasmodium that can infect man, and differences between them. problem of great proportions. Upon completion of the • Identify populations that are especially at risk for malaria and babesiosis • Understand the various facets of malaria that make it difficult to eradicate • Know the general life cycles of malaria and Babesiosis-sources of infection, lecture you will know the plasmodium species that infect infective/diagnostic stages, hosts. How are these cycles different from other parasitic protozoa? For malaria, know key diagnostic differences between P. falciparum and P. vivax an to cause malaria, identify the populations at risk of • Be familiar with antimalarial drug resistance and where it is a major problem. What drugs are failing in the world and what are viable alternatives? • Know aspects of malaria and babesia that make them emerging diseases • Describe why vaccines for malaria are elusive malaria and babesia. You will understand the facets of malaria that make it difficult to eradicate.

HSC4933. Emerging Infectious Diseases 4 You will know the general life cycle of malaria and babesia including sources of infection, infective and diagnostic stages, hosts. How they are different from other parasitic protozoa. For malaria you will know the key diagnostic differences between P.falicparum and P.vivax. You will become familiar with the antimalarial drug resistance and where in the world it is a major problem. Also, what are the alternative drugs available in the arsenal against malaria.

You will know aspects of malaria and babesia that make them emerging diseases and learn why vaccines for malaria are so elusive.

Slide 5 This lecture will be the second part of Phylum Lecture 9: On the Menu . It will cover malaria and babesiosis. The • Phylum Apicomplexa pt. 2 slide shows the of these parasites. – Class , Order Haemosporida . Plasmodium spp. – Class Aconoidasida, Order . Babesia spp.

HSC4933. Emerging Infectious Diseases 5 Slide 6 Lets talk of malaria first. It kills more humans per year Malaria than any other parasite. The slides shows graphic that cover the entire spectrum of malaria from clinical cases to diagnostics, treatment and preventive measures.

One cannot over-estimate the seriousness of the disease as one child dies per minute due to malaria according to the WHO. HSC4933. Emerging Infectious Diseases 6

Slide 7 Malaria Intro Video

• http://video.nationalgeographic.com/video /player/science/health-human-body- sci/health/malaria-sci.html

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Slide 8 Malaria is a disease known to man since antiquity. Malaria: Background Approximately 156 species that infect vertebrates. There • Malaria is the most important parasitic disease affecting man are four major species that infect humans and there is • Disease of antiquity – First described in Chinese writings in one more that is now an emerging problem in Malaysia 2700 B.C. • Approximately 156 species of that we will talk about later. Plasmodium which infect various species of vertebrates. – Four species are considered true parasites of humans (int. host) • Transmitted by Anopheles mosquitoes Malaria is transmitted by the mosquitoes of the genus (def. host) Anopheles.

The top picture is an enhanced image showing the erythrocytes. A couple are infected and you can see the tiny parasites in them. One of the infected cells is lysed and is releasing the tiny parasite forms called merozoites.

The lower image is of a female anopheles mosquito taking a blood meal.

Slide 9 As I said malaria is the most important parasitic disease Public Health Impact of man. These are some of the numbers for malaria from • World Health Organization estimates – About 3.4 billion people are at risk of malaria the WHO. These vary from year to year. The numbers – 270 million new infections per year in 2012 – 627000 malaria deaths in 2012 wont be asked in the quizzes. About 3.4 billion people are – 90% of deaths occur in Africa (south of Sahara) • Occurs in tropical and temperate regions worldwide at risk of malaria. In 2012 there were about 207 million • Most cases in Africa, followed by Asia and South America cases of malaria and about 627,000 deaths. About 90% of • Dependent upon vector and host, other factors • Global “contraction” from 1900-1950 and accelerated during 1950-1965 cases occur in Africa(south of the Sahara).

Malaria is found in tropical and temperate regions of the world. After Africa, the highest number of malaria cases occur in Asia and South America. There was a global contraction of the number of cases of malaria following the malaria control efforts from 1900-1950, but the number of cases accelerated from 1950-1965 due to resistance to insecticides amongst other factors.

Slide Lets look at some of the facts of the Plasmodium species. Plasmodium spp. Facts

10 • P. vivax • P. malariae Plasmodium vivax is the most common species of – Most common, except in Africa – Global, but patchy 72h cycle – Temperate and tropical • P. ovale – 48h cycle, relapse, hypnozoites, Plasmodium that causes malaria except in Africa where P. – Mainly in tropical Africa and drug resistance Oceania • P. falciparum – 48h cycle, relapse falciparum is more common. It occurs in temperate and – Tropical • P. knowlesi – Holoendemic in much of Africa – New emerging species in tropical regions and has a 48 hour cycle. It can relapse – 48h cycle, mortality, Tropical regions, humans drug resistance – Malaysia, 24 h. cycle and is due to hypnozoites which we will discuss in a short – Most lethal while. Drug resistance is a serious problem with P. vivax.

The next species is P. falciparum which is endemic in much of Africa. This also has a 48 hour cycle and high mortality. It also has concerns of drug resistance. It is the most lethal form of Malaria.

P. malariae is global but a patchy 72 hour cycle.

P.ovale is found mainly in tropical Africa and Oceania. It has a 48 hour cycle and causes relapses.

P.knowlesi is recently emerging in Malaysia where it has been suspected to have been transmitted from monkeys to humans. It has a 24 hour cycle.

Slide The malaria parasite life cycle involves two hosts. During Malaria: Life cycle a blood meal, a malaria-infected

11 Mosquito is female Anopheles mosquito inoculates sporozoites into definitive host

Man is the human host . Sporozoites infect liver cells and intermediate host mature into schizonts , which rupture and release merozoites . (Of note, in P. vivax and P. ovale a dormant stage [hypnozoites] can persist in the liver and cause

See animated life cycle link in BB relapses by invading the bloodstream weeks, or even HSC4933. Emerging Infectious Diseases 11 years later.) After this initial replication in the liver (exo- erythrocytic schizogony ), the parasites undergo asexual multiplication in the erythrocytes (erythrocytic schizogony ). Merozoites infect red blood cells . The ring stage trophozoites mature into schizonts, which rupture releasing merozoites . Some parasites differentiate into sexual erythrocytic stages (gametocytes) . Blood stage parasites are responsible for the clinical manifestations of the disease. The gametocytes, male (microgametocytes) and female (macrogametocytes), are ingested by an Anopheles mosquito during a blood meal . The parasites' multiplication in the mosquito is known as the sporogonic cycle . While in the mosquito's stomach, the microgametes penetrate the macrogametes generating zygotes . The zygotes in turn become motile and elongated (ookinetes) which invade the midgut wall of the mosquito where they develop into oocysts . The oocysts grow, rupture, and release sporozoites , which make their way to the mosquito's salivary glands. Inoculation of the sporozoites into a new human host perpetuates the malaria life cycle .

Slide Worldwide distribution of malaria This map shows the distribution of malaria in the world. As seen the most critical areas for malaria are South Asia, 12 Southeast Asia and Africa.

From Public health challenges and prospects for malaria control and elimination Pedro L Alonso & Marcel Tanner Nature Medicine 19, 150–155 (2013) doi:10.1038/nm.3077 12 Slide Malaria affects infants and small children more severely Who does malaria affect? than adults. Especially under-five children. Non-immune 13 • Infants & young children (under 5 yrs. old) • Non-immune pregnant women pregnant women can undergo miscarriage. Pregnant – High rates of miscarriage and cause over 10% of maternal deaths (soaring to a 50% death rate in cases women with partial immunity have anemia when they of severe disease) annually. • Semi-immune pregnant women risk severe anemia and impaired fetal growth even if they show no get malaria. Also at risk are women with HIV. Non- signs of acute disease. • HIV-infected pregnant women are also at increased immune travelers and tourists can get infected and carry risk. • Non immune (tourist) the parasite to non-endemic regions.

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Slide Costs to individuals and their families Malaria – the cost -purchase of drugs for treating malaria at home; • Costs to individuals and their families - purchase of drugs for treating malaria at home; 14 - expenses for travel to, and treatment at, dispensaries and clinics; -expenses for travel to, and treatment at, dispensaries - lost days of work; absence from school; - expenses for preventive measures; - expenses for burial in case of deaths. and clinics; • Costs to governments include - maintenance, supply and staffing of health facilities; -lost days of work; absence from school; - purchase of drugs and supplies; - public health interventions against malaria, such as insecticide spraying or distribution of insecticide-treated bed nets; - lost days of work with resulting loss of income; and -expenses for preventive measures; - lost opportunities for joint economic ventures and tourism.

• Direct costs (for example, illness, treatment, premature death) have been -expenses for burial in case of deaths. estimated to be at least US$ 12 billion per year. The cost in lost economic growth is many times more than that. HSC4933. Emerging Infectious Diseases 14 Costs to governments include - maintenance, supply and staffing of health facilities; - purchase of drugs and supplies; - public health interventions against malaria, such as insecticide spraying or distribution of insecticide-treated bed nets; -lost days of work with resulting loss of income; and -lost opportunities for joint economic ventures and tourism.

Direct costs (for example, illness, treatment, premature death) have been estimated to be at least US$ 12 billion per year. The cost in lost economic growth is many times more than that.

Slide The reasons why malaria is still a problem include Why is it getting worse? substandard drugs or counterfeit drugs, resistance to 15 • Substandard, counterfeit drugs drugs. This is a serious problem as newer drugs have to • Drug resistance • Insecticide resistance be constantly developed for the fight against malaria. • Deterioration of public health services • Environmental changes Insecticide resistance in malaria has caused the malaria • No vaccine control program to slow down. Newer insecticides are now available that are different from those initially used HSC4933. Emerging Infectious Diseases 15 for vector control.

The deterioration of public health services especially in developing countries impedes public heath education and surveillance efforts for the control of malaria.

Environmental changes have led to the spread of the vectors and increased risk to naïve populations.

Also, as yet there is no effective vaccine against malaria.

Slide Anopheles mosquito species are the vectors for malaria. Mosquitoes and Malaria Only the females bite humans to take a blood meal as Anopheline Mosquitoes • Approximately 430 known species, 30-50 transmit 16 malaria • Life cycle – 7 to 20 days (egg to adult) they need the protein for laying their eggs. – Females mate once and lay 200-1000 eggs in 3-12 batches over a lifetime – Find their host by chemical and physical stimuli – Average life span of adult mosquito < 3 week

Malaria development • Development in mosquito (extrinsic incubation There are approximately 30-50 species that can transmit period)=7 to 12 days • Each male & female gametocyte produce >10,000 sporozoites malaria.

• Important vector species begin entering houses in the early evening, often at sunset. • Important vector species often begin leaving houses just before or during sunrise. The life cycle of the mosquito is from 7 to 20 days. The HSC4933. Emerging Infectious Diseases 16 females mate once and lay about 200-1000 eggs.

Around evening and dusk, the vector mosquitoes begin entering the houses and they leave before sunrise. So the risk of getting a mosquito bite and malaria is highest between dusk to dawn.

Slide The ecological features of the region and the abundance Ecology and malaria transmission of mosquito breeding habitats determines the abundance • Determines presence of larval habitats and abundance of 17 vectors of the vector mosquitoes. Amongst factors that influence • Influences distribution and abundance of humans (mosquito- human-mosquito cycle of transmission) • Factors that influence presence, abundance and longevity of the presence, abundance and longevity of mosquitoes mosquitoes. – Temperature – Rainfall are temperature, rainfall, relative humidity and – Relative Humidity – Topography . Altitude, elevation topography like altitude, soil type, and vegetation. . Soil Type . Land cover (vegetation)

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Slide This map shows the distribution of the different species Distribution of malaria vectors of anopheline vectors that transmit malaria. 18

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Slide Malaria: 2013 This slide shows the species-wise distribution of malaria in the world. As can be seen from the map > 90% P. vivax 19 infection is singularly found in China, Afghanistan, some countries of Central and West Asia, Argentina, Bolivia and Mexico. Falciparum is found in most of the African countries. Both Falciparum and vivax are co-endemic in India, Southeast Asia, Eastern Africa around the horn of Africa and northern South America along with 19 Madagascar.

Slide This slide shows the malaria elimination that has been achieved country-wise. The green regions have no 20 malaria, the blue regions are working on elimination of malaria while the red ones are currently working on the control of malaria.

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Slide While today there is no malaria in the US, our country is Malaria in the U.S. no stranger to malaria. Malaria was endemic in the US in • Malaria was endemic in the US until 21 the late 1940's. • Most of the transmission occurred the until the 1940’s and most of the transmission in the southeastern states. • Control efforts conducted by the occurred in the southeastern states. The control efforts state and local health departments, supported by the federal government, resulted in the disease being eradicated by 1949. instituted by the local and state health departments • Such measures included drainage, removal of mosquito breeding sites, along with federal support resulted in the disease being and spraying (occasionally from aircrafts) of insecticide eradicated in the US by 1949. The measures included drainage, removal of mosquito breeding sites and HSC4933. Emerging Infectious Diseases 21 spraying of insecticides.

Slide Recent Stats for Malaria in the This graphic shows the number malaria cases in the US US- CDC

1800 since 1980 to 2011. The number of cases of malaria has U.S. military personnel 1600 22 U.S. civilians increased in the recent years. Foreign residents and US 1400 Foreign residents 1200 Status not recorded citizens that travel abroad make up most of the cases. So 1000 800 it is necessary to take malaria prophylaxis when visiting 600

400 the endemic regions.

200

0

Malaria Surveillance — United States, 2011 22 Surveillance Summaries. November 1, 2013 / 62(ss05);1-17 Slide Plasmodium species in malaria cases This graph shows the cases of malaria depending on the in the US 2008-2011 (CDC) species of Plasmodium. Falciparum followed by vivax are 1000 23 900 the most prominent aetiological agents. 800 700 P. falciparum 600 P. vivax P. malariae 500 P. ovale P. knowlesi 400 Mixed Undetermined 300

200

100

0 2008 2009 2010 2011

Malaria Surveillance — United States, 2011 23 Surveillance Summaries. November 1, 2013 / 62(ss05);1-17

Slide Number of malaria cases, by state or territory in This graph shows the state-wise incidence of malaria which case was diagnosed — United States, 2011 cases in the US in 2011. NYC leads with 238 cases and this 24 is not surprising the number of immigrants in NYC. It is followed by California, Maryland and Florida.

Malaria Surveillance — United States, 2011 24 Surveillance Summaries. November 1, 2013 / 62(ss05);1-17

Slide Minimizing Risk of Re-emerging Lets talk of minimizing the risk the risk of re-emerging malaria malaria in U.S. in the US. • Prevention of malaria in travelers 25 • Ensure prompt diagnosis and treatment of all infected persons • Containment of local outbreaks of malaria This is focused on prophylaxis for travelers and education for • Conduct surveillance of malaria cases • Sensitize local communities to the risk of use of mosquito repellants. All infected persons should be malaria • Encourage personal protection measures to prevent mosquito bites promptly diagnosed and treated to minimize transmitting the • Conduct vector control activities • During 1963-1999, 93 cases of infection to mosquito vectors. When an outbreak of malaria is transfusion-transmitted malaria were reported in the United States reported, it is essential to amp up the mosquito control efforts

HSC4933. Emerging Infectious Diseases 25 to eliminate any mosquitoes that may have acquired the parasite. Active surveillance of malaria cases and sensitization of the communities for the risk of malaria.

During 1963-1999, there were 93 cases of transfusion transmitted malaria were reported in the United States.

Slide Plasmodium knowlesi is the newest kid on the block for Plasmodium knowlesi human plasmodial infections. It naturally infects long- • Infects long-tailed macaques 26 • Previously diagnosed as P. malariae in humans tailed macaques in Malaysia. The first cases were initially • 24 hour cycle, higher parasitemia than P. malariae misdiagnosed as P.malariae, but the parasitemia was • Exists primarily in Malaysia • 2008 study: P. knowlesi DNA was detected in 27.7% samples from Sarawak hospitals, 83.7% from Sabah, 5 from Pahang higher than in P.malariae and had a 24 hour cycle. In • Similar infections have been found in Thailand, the Philippines, and Singapore • Economic exploitation of the forest is 2008, a study found P.knowlesi DNA in 27.7 % samples perhaps bringing monkeys, mosquitoes and humans into increased contact. from Sarawak hospitals and 83.7% samples from Sabah. Similar infections have been found in Thailand, HSC4933. Emerging Infectious Diseases 26 Philippines and Singapore.

Economic exploitation of the forest is perhaps bringing the monkeys, humans and mosquitoes in increased contact.

Slide Here is an example of acquiring P. knowlesi while P. knowlesi: Emerging Disease traveling abroad. This is a great case to illustrate how 27 infection can be imported into the US and cause a serious outbreak given that we have competent Anopheles vectors here.

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Slide Lets look at the clinical part of malaria. MALARIA: Prodromal symptoms

• The first symptoms of malaria after the pre-patent period 28 (period between inoculation and detectable stages: when the sporozoites undergo schizogony in the liver) are called the The clinical symptoms of malaria include Headache, primary attack. It is usually atypical and may resemble any febrile illness. malaise, aching bones, limbs or back, loss of appetite, • Headache • Feeling of weakness and exhaustion nausea and vomiting. • Aching in bones, limbs, or back • Loss of appetite • Desire to stretch or yawn • Nausea and vomiting These are not specific and resemble any febrile illness.

28 HSC4933. Emerging Infectious Diseases Slide Prepatent & incubation periods of prepatent period is the period between infection of the human malaria host and the earliest time at which the causative agent 29 PREPATENT PERIOD INCUBATION PERIOD can be recovered from the patient or, in the case of P. falciparum 11 - 14 days 8 - 15 days parasites, eggs or larvae can be recovered from feces, P. vivax 11 - 15 days 12 - 20 days P. ovale 14 - 26 days 11 - 16 days urine or blood. It is usually shorter than the incubation P. malariae 3 - 4 weeks 18 - 40 days period but may be longer in some parasitic infestations, e.g. hookworm infestation in puppies.

HSC4933. Emerging Infectious Diseases 29 The table gives the pre-patent and incubation periods for the different Plasmodium species. Vivax and falciparum have similar prepatent periods but different incubation periods which overlap to some extent.

Slide The clinical symptoms of malaria are caused by the intra- Uncomplicated Malaria erythrocytic stages. The parasite and red cell material • The asexual intra-erythrocytic stage causes all pathophysiological processes – Parasite and red cell material released with schizont rupture, resulting in chills 30 and high grade fever. released release by schizont rupture results in chills and • Paroxysms – Episodes of chills and fever – Begins with cold stage of up to 1 hr duration-Profuse sweating as body temperature falls high grade fever. – Fever stage follows rapidly for 6-12 hr . Nausea, Vomiting, Rapid pulse • The pattern of intermittent chills/fever mirrors the synchronized parasite development in an infected person’s blood (48 or 72 hours) – Benign tertian: P. vivax – Malignant tertian : P. falciparum Paroxysms are episodes of chills and fever. It begins with – Quartan : P. malariae • Recrudescences= reinfection as result of parasites not being cleared • Relapses= result of P. vivax and P. ovale stages that hide in liver cold stage of upto 1 hour and there is profuse sweating as the body temperature falls. Fever stage follows rapidly HSC4933. Emerging Infectious Diseases 30 for 6-12 hours and is characterised by nausea, vomiting and rapid pulse.

Now depending on the pattern of intermittent chills/fever mirrors the synchronized parasite development in an infected person’s blood (48-72 hours)

Benign tertian for P.vivax Malignant tertian for P.falciparum Quartan for P.malariae

Recrudescence is the reinfection as results of parasites not being cleared.

Relapse is the result of P.vivax and P.ovale stages that hide in the liver (hypnozoites)

Slide Severe Malaria and other Severe malaria occurs when P. falciparum infections are manifestations complicated by serious organ failures or abnormalities in • Cerebral malaria, with abnormal Severe disease with life-threatening 31 behavior, impairment of consciousness, complications- P. falciparum convulsions, seizures, coma, or other • Hypoglycemia the patient's blood or metabolism. The manifestations of neurologic abnormalities • Severe anemia due to hemolysis • Septicemia (destruction of red blood cells) • Gastrointestinal bleeding • Hemoglobinuria (hemoglobin in the urine) • Pneumonia severe malaria include: due to hemolysis (Blackwater fever), renal failure • Pulmonary edema or acute respiratory • The clinical presentation can vary distress syndrome (ARDS) substantially depending on the • Abnormalities in blood coagulation and infecting species, the level of thrombocytopenia (decrease in blood platelets)-bleeding/clotting disorders parasitemia, and the immune status of • Cardiovascular collapse and shock the patient. • Metabolic acidosis • Hyperparasitemia Don’t memorize, but know spectrum of severity and how different from uncomplicated malaria ARDS which may occur even after the parasite counts 31 HSC4933. Emerging Infectious Diseases have decreased in response to treatment. It is important to know cerebral malaria and severe anemia. The hemolysis leads to hemoglobin in the urine and the diseases is then known as blackwater fever.

Severe anemia can also lead to cardiovascular collapse and shock. There can be hyperparasitemia in which the parasite number are very high.

Severe disease in P.falciparum infection include hypoglycemia, septicemia, GI bleeding and pneumonia.

The clinical presentation can vary substantially depending on the infecting species, the level of parasitemia, immune status of the individual.

There is an age dependency for disease complications: severe anemia occurs early in childhood; cerebral malaria, later. After repeated infections, children develop anti-malarial immunity that controls parasite growth and limits disease from subsequent infections. Adults living in endemic regions rarely experience severe malaria morbidity.

Slide Lets now look at Cerebral Malaria. P. falciparum- Cerebral malaria

• Most common clinical presentation of severe 32 malaria in man It is seen only in infection with P. falciparum. And is the • Definition – Parasitized red blood cells (PRBCs) adhere to the most severe malaria in man. cerebral microvasculature, causing blockage of the blood's pathway - stops blood flow, leading to a shortage of oxygen and nutrients those areas of the brain (hypoxia). – Unrousable coma It is seen when the parasitised RBCs adhere to the – Other causes of encephalopathy have been excluded (viral infections, head injury, etc) – Mortality rate of ~22% despite treatment cerebral vasculature and cause blockage of leading to ischemia in the affected parts of the brain. HSC4933. Emerging Infectious Diseases 32

There is unarousable coma. Differential diagnosis includes different causes of encephalopathy. It has a high mortality despite treatment.

Slide Malaria affects pregnancy adversely and can lead to Pregnancy and Malaria maternal anemia, fetal loss, premature delivery, 33 • In sub-Saharan Africa, there are 400,000 cases of severe maternal anemia and 75,000-200,000 infant deaths annually. intrauterine growth retardation and delivery of low birth – 10,000 maternal deaths per year. • Adverse effects on both mother and fetus, including maternal weight infants. anemia, fetal loss, premature delivery, intrauterine growth retardation, and delivery of low birth-weight infants. • It is a particular problem for women in their first and second pregnancies and for women who are HIV-positive. It is a particular problem for women in their first and • High transmission area vs. low transmission area: anemia and birth outcomes differ second pregnancies and for women who are HIV positive.

33 HSC4933. Emerging Infectious Diseases When one compares the high vs low transmission areas, the anemia and birth outcomes differ.

Slide Diagnosis depends on lab tests and a good clinical history Diagnosis: Important facts especially the travel history. This helps in figuring out the Thick and thin blood smears • Elicit a good travel history 34 • Ethnic origin of patient or family infecting species, ethnic history, history of drug use, members • History of previous episodes of malaria occupation. • Blood transfusions or i.v. drug use • Occupation • Giemsa stained blood smears • PCR • Dipstick antibody tests to differentiate Traditionally a thick and thin smears are made, the thick species • DNA staining smear is to detect the infection while the thin smear helps identify the microscopic features of the parasite HSC4933. Emerging Infectious Diseases 34 and identify the species.

Dipstick antibody tests help to differentiate species.

Slide Ring stages Gametocyte We will discuss in detail the diagnostic criteria for P. vivax Diagnostic criteria and P. falciparum as they are the most significant species. P. falciparum 35 • Mostly rings or gametocytes present – Trophozoites and schizonts cytoadherence • Crescent shaped gametocytes • 24 to 36 merozoites (if schizont present) For P.falciparum mostly the rings forms or gametocytes • No Schuffner’s stippling • Infected erythrocyte not enlarged are present. The gametocytes are crescent shaped and Plasmodium vivax • All stages present • Infected erythrocyte enlarged the RBC is not enlarged. If a schizont is present, it has 24- • Schuffner’s stippling (dots) • 12 to 24 merozoites 36 merozoites. • Oval gametocyte almost fills erythrocyte

HSC4933. Emerging Infectious Diseases 35 For P . Vivax all stages are present in the blood and there is stippling (Schuffner’s stippling) of the erythrocytes with enlargement. Schizonts have 12-24 merozoites. The gametocytes are oval and fill the RBC.

Slide This slide shows the different stages of P. vivax and P. falciparum vs. P. vivax

Notice the differences? falciparum for comparison. As you can see, the stippling 36 is present in vivax and absent in falciparum. The RBC is enlarged in vivax and not in the other. Also note the shape of the gametocytes. They are banana shaped in falciparum and oval shaped in vivax.

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Slide The treatment of malaria differs according to the Antimalarial Treatment infecting species and the geographic location where the • Treatment varies according to the infecting species, the geographic 37 area where the infection was acquired, and the severity of the disease • Treatment for malaria should not be initiated until the diagnosis has infection was acquired and the severity of the disease. been confirmed by laboratory investigations. • Treatment of infection – Acute, uncomplicated malaria – Severe or cerebral malaria • Radical cure Treatment of malaria should not be initiated until the • Prophylaxis – Causal, Suppressive – Post-exposure diagnosis of the infecting species has been confirmed by • Intermittent Presumptive Treatment (IPT) – Infants (IPTi) – Pregnancy (IPTp) the lab investigations.

HSC4933. Emerging Infectious Diseases 37 The treatment of malaria has various concepts and it can seem all very confusing.

As listed out in the bullets on the slide, the treatment is for two types of malaria : the first is the Acute uncomplicated malaria which is treated with specific drugs depending on the region of the world and the resistance pattern to chloroquine and other antimalarial drugs. The second is the severe or cerebral malaria which is treated with quinidine gluconate and either doxycycline or clindamycin.

Radical Cure - treatment intended to achieve cure of P. vivax or P. malariae malaria. These two species have exoerythrocytic [outside of red blood cells i.e. in the liver] stages. Requires primaquine treatment, which destroys latent exoerythrocytic stage parasites (hypnozoites). Typical case patient: a returned traveler from Central America who has had a relapse of malaria.

Prophylaxis for malaria can be of two type. The first is taken prior to travel and continued during travel and the other is post exposure.

There is also something called intermittent Presumptive treatment for infants and pregnant women. This is in endemic regions to clear existing parasites and to prevent new infections.

Slide Lets look at the treatment of severe malaria. Treatment: Severe Malaria

38 • Choose appropriate antimalarial drug and The treatment is based on the following things, An route of administration • Follow blood glucose carefully appropriate antimalarial drug and route of • Administer I.V. fluids for shock and administration. Intravenous route is better than oral as hypovolemia • Administer oxygen by nasal catheter the oral bioavailability may be lower than I/V and the • Consider replacing erythrocytes for patient may be in coma so I/V is the only choice. hematocrit of 30 or parasitemia > 10%

HSC4933. Emerging Infectious Diseases 38 Monitoring of blood glucose as treatment with quinine can lead to drops in blood sugar and its inherent risks.

I/V fluids should be administered for shock and hypovolemia

Oxygen is administered by nasal catheter to ensure adequate oxygen delivery.

Sometimes patients need replacement of RBCs if their hematocrit is 30 or if the parasitemia is greater than 10%.

Slide Cerebral malaria is treated with the following drugs. The Treatment- Cerebral Malaria choice of the drugs depends again on the geographic 39 • Quinine, intravenous – Slow infusion avoids cardiovascular toxicity and location and known resistance patterns as we will see in a hypoglycemia • Quinidine gluconate, intravenous short while. – Very effective, but adverse cardiac events • Artemisinin derivatives – Rapidly acting – Several derivatives and formulations . Artesunate drug of choice for severe disease Quinine is the oldest antimalarial drug and is used as an – Compassionate use IND in US (via CDC) – >30% more effective than quinine in preventing death in cerebral malaria I/V infusion. The infusion is given slowly to avoid cardiovascular toxicity and hypoglycemia. HSC4933. Emerging Infectious Diseases 39

Quinidine gluconate is also similar but has risk of adverse cardiac events. In fact quinidine is an anti-arrhythmic drug that is used to treat cardiac arrhythmias.

Artemisinin derivatives are rapidly acting and there are several derivatives and formulations. In the US, High quality-intravenous artesunate is available only to malaria patients hospitalized in the United States who need intravenous treatment because of: severe malaria disease high levels of malaria parasites in the blood inability to take oral medications lack of timely access to intravenous quinidine quinidine intolerance or contraindications quinidine failure The drug is provided to the hospitals, upon request and on an emergency basis, by the CDC Drug Service or by one of the CDC Quarantine Stations located around the country.

Slide This slide summarizes the problems with the different Problems with antimalarial drugs anti-malarials. As we can see, resistance is a major issue DRUG PROBLEMS 40 Artemisinin Recrudescence, Neurotoxicity with the drugs. Atovaquone Resistance Azithromycin Limited efficacy Chloroquine Resistance Doxycycline Phototoxicity, GI intolerance Fansidar Resistance, Allergic Rxns Halofantrine Cardiotoxicity Mefloquine Resistance, Psychiatric effects Primaquine Therapeutic Index, Resistance? Proguanil Resistance, Mouth ulcers Quinidine gluconate Going off the market? Quinine Resistance, Tinnitus

HSC4933. Emerging Infectious Diseases 40 Slide Time to Development of Resistance to This is a great graph that shows the decreasing time Antimalarial Drugs interval from discovery of a new drug for malaria and the 41 Chloroquine 16 years emergence of resistance.

Fansidar 6 years

Mefloquine 4 years

Atovaquone 6 months

1940 1950 1960 1970 1980 1990

Slide The problem of resistance is so important that there is now surveillance for emergence of resistance and global 42 bodies to address the issue as seen in this slide.

HSC4933. Emerging Infectious Diseases 42

Slide Chloroquine was discovered during WW II. It was the Chloroquine (CQ) magic bullet effective against all species. However, now

43 • Discovered during WW II • Effective against all Plasmodium spp. there is widespread resistance. It acts by accumulating • CQ is trapped in the parasite food vacuoles where it is toxic – Inhibits polymerization of hemazoin inside the erythrocyte in food vacuoles where it is toxic. It and free heme kills the parasite • ‘Magic bullet’ that was basis of 1960s malaria eradication campaign prevents polymerisation of hemazoin. The parasite makes • Resistance first emerged in early ’60s in S. America and SE Asia – Resistance conferred by complex hemoglobin less toxic by converting it to hemazoin, mutations in a Plasmodium falciparum chloroquine resistance transporter gene (pfcrt) chloroquine inhibits this process and effects death of the – Big problem in Africa, Asia parasite. But resistance to CQ emerged in the early ‘60’s HSC4933. Emerging Infectious Diseases 43 in South America and SE Asia. The resistance was due to complex mutations in the parasite chloroquine resistance transporter gene and now is a huge problem in Africa and Asia.

Slide Spread of chloroquine resistant This shows the spread of CQ resistant P.falciparum. It was Plasmodium falciparum first in Colombia in 1959 and in Thai-Cambodia in 1957. It 44 is theorized that the first resistant in 1957 spread later to other parts of the world making CQ useless.

HSC4933. Emerging Infectious Diseases 44

Slide Mefloquine developed by the US Army. It is useful in Mefloquine (Lariam) regions where CQ resistance is present but recent reports 45 • Prophylaxis - in CQ & multi-drug resistant have indicated resistance to it. It is also used in regions • Treatment - in CQ & multi-drug resistant combination with Artemisinin. It has started to lose regions effectiveness against P. falciparum – Combined with artesunate to treat mefloquine resistant malaria in SE Asia – For P. vivax or P. falciparum

HSC4933. Emerging Infectious Diseases 45

Slide Artemisinin is from the herb Artemesia annua. Originally Artemisinin (Qinghaosu) used by Chinese for treatment of fever and is known by 46 • Harvested from the Chinese herb Artemesia annua (sweet wormwood) the name of ‘qinghaosu’. There are many derivatives that • Many derivatives • 200 BC-China: recognized as herbal are now used for treatment of malaria. The structure remedy of hemorrhoids and fever • 1972 identified as active constituent show the endoperoxide bridge that is responsible for the of Artemesia annua • 1999 Artemisinin combination O O key activity. In 1972 they identified the active compound therapy (ACT) O O and in 1999 ACT was started for treatment of malaria. O

C H O 15 22 5

Slide Benefits of artemisinin is that it kills the gametocytes Artemisinin Treatment of Malaria unlike some other drugs. It is a s cheap alternative • Rapid relief from symptoms and fast clearance times 47 • Broad stage specificity with gametocidal activity compared to other drugs but could still be expensive for • Cheap alternative to other drugs • Not recommended for prophylaxis because of short poorer countries. It gets eliminated very fast by the body elimination time • Animal studies: neurotoxicity at high doses and also death of embryos, and morphological abnormalities in early pregnancy so combination with another drug is necessary. Also it • Can be combined with other drugs for effective treatment (ACT) has issues with teratogenic effects and neurological • Only treatment for severe malaria besides quinine • Resistance reported in 2009-2010. toxicity necessitates cautious use.

It is the only drug for treatment of severe malaria besides quinine.

Resistance to artemisinin has been reported in 2009- 2010. So there is an urgent need to identify newer drugs for treatment of malaria.

Slide WHO has recommended the use of ACT in areas of high Artemisinin Combination Therapy (ACT) malaria transmission and where drug resistance to • WHO issued new guidelines on malaria treatment and 48 requested pharmaceutical companies to end the marketing and sale of "single-drug" artemisinin malaria antimalarial drugs is prevalent. medicines, in order to prevent malaria parasites from developing resistance to this drug (1-20-06 Press ACT achieves its antimalarial effect through an initial release). • The artemisinin component – Reliably efficacious, rapidly effective rapid reduction in parasite biomass attributable to the • Partner drug(s) – Ensures high cure rate short-acting but highly potent artemisinin drug, with the – Very well tolerated – Reduces gametocyte carriage – Reduces de-novo resistance to partner subsequent removal of remaining parasites by a less- – Prophylactic activity effective but slower eliminated partner drug.

The use of the partner drugs ensures high cure rate although now with resistance to artemisinin, it has started to fall in some regions, the treatment is well tolerated, reduces gametocyte carriage, reduces de novo resistance to partner drug.

Slide ACT Partner drugs, CQ resistance This slide shows the partner drugs in different parts of the world depending on the resistance patterns. Various 49 drugs are used as partner drugs such as lumefantrine, amodiaquine, mefloquine, sulfadoxine and pyrimethamine piperaquine. The bottom right map shows the regions where P.vivax is resistant to CQ.

Global report on antimalarial drug efficacy and drug resistance: 2000–2010. WHO 49

Slide So, how do you correctly treat a It can be very confusing to consider the preventive patient? medication to take if one is visiting a certain part of the • Treatment of depends on many factors including disease 50 severity, the species of malaria parasite causing the infection, and the part of the world in which the infection was acquired. world. – Planning, Case history very important • Think about the probability that the organism is resistant to certain antimalarial drugs. • Additional factors such as age, weight, and pregnancy status may limit the available options for malaria treatment. The points to consider are the region where you are • Guidelines for U.S. Travelers – http://www.cdc.gov/malaria/diagnosis_treatment/treatment.html traveling so that the treatment can be started ahead of Interactive world map for malaria prevalence/risk: http://apps.who.int/tools/geoserver/www/ith/index.html time. If you get infected , you need to provide detailed CDC list of malaria countries and risk: http://wwwnc.cdc.gov/travel/yellowbook/2010/chapter- 2/malaria-risk-information-and-prophylaxis.aspx information of the places you have traveled. HSC4933. Emerging Infectious Diseases 50

Also, age, weight and pregnancy status could limit the choice of drugs.

Detailed information for US travelers is available on the CDC website.

Slide The prevention of malaria is very simple in theory but Prevention difficult in practice due to many different factors. • Reduce the transmission of 51 the disease by mosquito control • Mosquito nets treated with long-lasting insecticide, a very cost-effective method It is primarily focused on avoiding getting bitten by • Indoor residual spraying of insecticides. mosquitoes, residual indoor spray to kill vectors, early • Repellents • Drugs- all groups- kill parasites diagnosis and treatment prophylaxis while traveling. • Vaccines -block infection, kill parasite • Pregnant women Vaccines are still under development HSC4933. Emerging Infectious Diseases 51

Slide Prevention and Control of Malaria Malaria has a significant effect on pregnancy. The During Pregnancy intermittent therapy for malaria in pregnancy help reduce • Intermittent preventive treatment (IPT)-antimalarial treatment 52 given at regular intervals during pregnancy, anemia and adverse mother and child outcomes. The – Two to three doses of sulfadoxine-pyrimethamine (SP) administered to a pregnant woman through antenatal care services. This protects pregnant women from possible death and anemia and also prevents malaria-related low birthweight in infants drugs used for this are sulfadoxine and pyrimethamine. • Insecticide-treated bed nets (ITN), indoor residual spraying • Febrile malaria case management. • Malaria prevention is particularly challenging in HIV-infected women, who might constitute up to 40% of the antenatal population in southern Africa. Other measures include Insecticide treated nets and – HIV-infected pregnant women are more likely to fail antimalarial treatment and require three or more doses of IPTp indoor residual spraying, febrile malaria case management. HSC4933. Emerging Infectious Diseases 52

Malaria prevention is particularly challenging in HIV positive women who constitute upto 40% of the antenatal population in Africa. This is because they are more llikely to fail treatment of malaria and need three or more doses of IPTp.

Slide Now lets talk a little about the vaccines for malaria. The Vaccines vaccine for malaria can be one that can act at the pre- • Pre-erythrocytic stages- directed 53 against sporozoites and/or liver stages (prevent blood-stage infection) erythrocytic stages. These are designed to prevent the • Against asexual blood stages are designed to reduce clinical severity invasion of the RBC and liver cells i.e. they prevent blood • Against mosquito stages are designed to halt development in the mosquito (transmission-blocking vaccines)- stage infection. • Major problem: antigens are constantly changing and developing a vaccine against these varying antigens The other type of vaccine can be against the asexual is very difficult blood stages and they are designed to reduce the clinical severity. HSC4933. Emerging Infectious Diseases 53

A third type of vaccine is one that is designed to block the development of the parasite in the mosquito. These are the transmission blocking vaccines.

The major problem in developing vaccine is that the antigens constantly changing.

Slide This slide taken form the presentation by David Kaslow, delivered at the Annual Meeting of the American Society 54 of Tropical Medicine and Hygiene (ASTMH) in 2012 shows the different vaccine candidates for malaria in their development path. The candidate that is currently in Phase III trials is the RTS,S vaccine.

Multilateral Initiative on Malaria Pan-African 54 Conference, Durban, South Africa : Results from a large- scale Phase III trial, presented in Durban in October 2013, show that the most clinically advanced malaria vaccine candidate, RTS,S, continued to protect young children and infants from clinical malaria up to 18 months after vaccination. Based on these data, GSK intends to submit, in 2014, a regulatory application to the European Medicines Agency (EMA). The World Health Organization (WHO) has indicated that a policy recommendation for the RTS,S malaria vaccine candidate is possible as early as 2015 if it is granted a positive scientific opinion by EMA. These latest results demonstrated that over 18 months of follow-up, RTS,S was shown to almost halve the number of malaria cases in young children (aged 5-17 months at first vaccination) and to reduce by around a quarter the malaria cases in infants (aged 6-12 weeks at first vaccination).

Slide These are some of the issues with control mechanisms Control: Mechanisms and Challenges and challenges to control of malaria. • Requires an integrated approach 55 – Vectors – Proper antimalarial drugs – Access to prompt, medical treatment • Factors contributing to disease The control of malaria requires an integrated approach – Reservoir-prevalence in humans – Vector-suitability of local anopheline as hosts-breeding preferences, flight/resting behavior, abundance, temp., rainfall, comprising of vector control, proper anti-malarial drugs humidity, – New hosts-nonimmune hosts – Local climatic conditions and prompt access to medical treatment. The vector • Local geographical and hydrogeographical conditions, human activities that can determine availability of and accessibility to mosquito breeding areas control itself is quite complex because it will depend on the vector habits and habitats, breeding locations, HSC4933. Emerging Infectious Diseases 55 preferences for resting and feeding on humans, abundance, temperature, rainfall and humidity.

The anti0malarial drugs are fast becoming less effective due to drug resistance. The endemic regions are mostly the poor developing regions of the world in the tropical and temperate regions where lack of resources is compounded by political strife and inadequate public health and healthcare infrastructure.

Slide One of the approaches for the control of malaria that has Genetic engineering and Malaria been experimented with is the use of transgenic 56 • Transgenic mosquitoes – Mosquitoes refractory to mouse mosquitoes. malaria in lab experiments- transgenic malaria-resistant mosquitoes have a selective advantage over nontransgenic mosquitoes? Blocking transmission of sporozoites – through the gut wall and into the Sterile male mosquitoes released into salivary glands. a given environment One of the strategies has been the generation of – Male mosquitoes carrying lethal genes causing death of newborns very young – Disadvantages: transgenic mosquitoes that are refractory to mouse . Could resistant mosquitoes be useful in the wild? They must survive better than non-resistant mosquitoes even when malaria. The studies showed that transgenic mosquitoes not exposed to malaria. . Not shown to work in Plasmodium falciparum did not do any better than the non-transgenic HSC4933. Emerging Infectious Diseases 56 mosquitoes when fed with non-malaria infected blood. This is not really advantageous as the transgenic mosquitoes do not show any fitness advantage over the non-transgenic mosquitoes. For the strategy to be effective, the transgenic mosquitoes would need to fare better than the non-transgenic mosquitoes.

Another strategy is to release sterile males into a given environment. A third strategy is to release males carrying a lethal gene causing death of newborns very young.

The challenges to using transgenic malaria resistant mosquitoes are that they must survive better than the non resistant mosquitoes even when not exposed to malaria.

Also, the strategy does not work in P.falciparum.

Slide The next parasite in this lecture is Babesia spp. Babesiosis Babesia spp. is a zoonotic infection that is transmitted by and is • Zoonotic disease maintained by the interaction of vectors, transport hosts, and animal 57 reservoirs. maintained in the wild by numerous animal reservoirs • More than 100 species have been reported, only a few have been identified as causing human infections. and has different transport hosts. • Babesia microti and Babesia divergens have been identified in most human cases • Ticks of the family Ixodidae transmit B. microti (and Lyme disease). • Transplacentally or perinatally acquired (congenital) babesiosis have been reported. There are more than a 100 species that have been • Blood transfusions-emerging problem reported but only a few have been known to cause human disease. The most significant species causing HSC4933. Emerging Infectious Diseases 57 human infections are Babesia microti and Babesia divergens.

The ticks of the Ixodidae family are responsible for transmission to humans. These are the same that are also responsible for the transmission of Lyme disease.

Babesiosis is an infection that can be transmitted by a pregnant woman to her unborn child and is an emerging problem with blood transfusions.

Slide The Babesia microti life cycle involves two hosts, which Life Cycle: Babesia include a rodent, primarily the white-footed 58 mouse, Peromyscus leucopus, and a tick in the genus Ixodes. During a blood meal, a Babesia-infected tick introduces sporozoites into the mouse host . Sporozoites enter erythrocytes and undergo asexual reproduction (budding) . In the blood, some parasites differentiate into male and female gametes, although HSC4933. Emerging Infectious Diseases 58 these cannot be distinguished by light microscopy . The definitive host is the tick. Once ingested by an appropriate tick , gametes unite and undergo a sporogonic cycle resulting in sporozoites . Transovarial transmission (also known as vertical, or hereditary, transmission) has been documented for "large" Babesia species but not for the "small" Babesia, such as B. microti . Humans enter the cycle when bitten by infected ticks. During a blood meal, a Babesia-infected tick introduces sporozoites into the human host . Sporozoites enter erythrocytes and undergo asexual replication (budding) . Multiplication of the blood-stage parasites is responsible for the clinical manifestations of the disease. Humans usually are dead-end hosts. However, human-to-human transmission is well recognized to occur via contaminated blood transfusions .

Slide Babesia is found worldwide but its prevalence in malaria Geographic Distribution endemic regions is unknown as they can be mistaken as • Worldwide, but little is known about the prevalence of Babesia in 59 malaria-endemic countries, where misidentification as Plasmodium probably occurs. malarial parasites. • Endemic areas are regions of tick habitat, including the forest regions of the Northeastern U.S. and temperate regions of Europe. • In Europe, most reported cases are due to B. divergens and occur in The forest regions of North America and Europe that splenectomized patients. • In the U.S., B. microti is the agent most frequently identified (Northeast mostly, less common in Midwest), and can occur in nonsplenectomized harbor the tick vector are endemic for babesiosis. individuals. • High number of asymptomatic infections • The first U.S. case of babesiosis was reported on Nantucket Island in 1966. Between 1968 and 1993, more than 450 cases of Babesia infections were confirmed in the United States. – An increasing trend over the past 30 years may be the result of restocking of In Europe, most reported cases are due to B. divergens the deer population, curtailment of hunting, and an increase in outdoor recreational activities. and they occur in splenectomized patients. In the US, HSC4933. Emerging Infectious Diseases 59 B.microti is the most frequent agent identified mostly in Northeast and less commonly in Midwest. And it can occur in non-splenectomized individuals.

There is high number of asymptomatic infections.

The first US case was reported in Nantucket in 1966

Slide Lets look at the disease, diagnosis and treatment of Disease, dx, tx Babesiosis. • Fever, chills, sweating, myalgias, fatigue, 60 hepatosplenomegaly, and hemolytic anemia. • Symptoms typically occur after an incubation period of 1 to 4 weeks, and can last several weeks. The disease is more severe in patients who are immunosuppressed, splenectomized, and/or elderly. The clinical diseases is characterized by fever, chills, • Infections caused by B. divergens tend to be more severe (frequently fatal if not appropriately treated) than those due to B. microti, where clinical recovery usually occurs. sweating, myalgia, enlargement of liver and spleen and

Laboratory Diagnosis: • Microscopic examination of thick and thin blood smears hemolytic anemia. stained with Giemsa. • Isolation of the organisms by inoculation of patient blood into hamsters or gerbils • Treatment: Clindamycin plus quinine or atovaquone plus azithromycin The symptoms occur after 1-4 weeks and they can last for HSC4933. Emerging Infectious Diseases 60 several weeks. The disease is more severe in patients who are immunosuppressed or splenectomized or the elderly.

Infections cause by B.divergens tend to be more severe and could be fatal in the absence of timely treatment. On the other hand B.microti infections usually recover clinically.

The laboratory diagnosis is by examination of thick and thin blood smears stained by Giemsa.

The organism is isolated by innoculation of hamsters or gerbils with the patients blood.

The treatment of Babesiosis is with Clindamycin with quinine or atovaquone with azithromycin

Slide Babesia is now recognized as one of the frequent Babesia and blood transfusion: U.S. transfusion transmitted infections. There have been • Babesiosis is the most frequent transfusion-transmitted infection 61 with approximately 162 cases reported since 1980 and 12 about 162 cases that were transfusion transmitted since associated fatalities in the period 2005–2008 • Currently, the blood supply is not 1980 and 12 fatalities associated with it in the 2005-2008 screened for Babesia • Donors are deferred if they have a fever at the time of donation or period. report a history of Babesia infection, but this practice alone is unable to prevent asymptomatic individuals with low levels of parasitemia from serving as donors. The current diagnostic methods are inadequate for the screening of donated blood. Also, individuals with very 61 low parasitemia are very difficult to detect.

The table on the right from a 2011 paper lists the aetiological Babesia species by the number of reported cases. As we can see, the most frequent is B.microti.

Below is one of the health advisory that was issued by the NY City DOH about transfusion associated Babesiosis in NYC.

Figure 1. Different forms of Babesia divergens in human RBCs as seen on a Giemsa-stained smear from in vitro Slide cultured parasites (ring, dividing figure eights, Maltese cross parasites, and multiply infected RBCs). This slide shows the different forms of Babesia divergens in human RBCs on a Giemsa stained smear. You can see 62 the different forms of the parasites like ring forms, dividing figure eights, Maltese cross forms as well as multiply infected RBCs.

Lobo CA, Cursino-Santos JR, Alhassan A, Rodrigues M (2013) Babesia: An Emerging Infectious Threat in Transfusion Medicine. PLoS Pathog 9(7): e1003387. doi:10.1371/journal.ppat.1003387 http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003387

Slide For prevention of Babesiosis, one should avoid the tick Prevention infested areas in seasons of high activity like summer • Avoid tick exposures 63 – Tick infested areas (high tick season between May and September, wear light colored clothing between May and September) – Cover skin with light clothing, searching for ticks after being outdoors and removing discovered ticks from the skin. to easily identify ticks and removing ticks that are – Applying bug repellent with DEET discovered on the skin. • Eradication? – Preventative measures seem to be more recommended over vector control. – Due to the relatively low prevalence of the disease and the presence of several reservoirs, Babesiosis is currently not a Eradication efforts would be a long-term project, which candidate for vaccine prevention. would significantly reduce the prevalence of both HSC4933. Emerging Infectious Diseases 63 Babesiosis and Lyme disease.