Prof. Dr. Md. Akram Hossain March 09 means, "Hidden spore" (crypto - hidden). In recent years Cryptosporidium parvum gained its importance as the causative agent of diarrhea in immunocompromised specially AIDS patients.

Prof. Muhammad Akram, 1/7/2014 Cryptosporidium 2 ® Occurs worldwide. ® The prevalence varies from region to region. In Europe, prevalence is most often 1-2% of those screened, while in North America prevalence ranged from 0.6 to 4.3%. Prevalence in Asia, Australia, Africa, Central and South America is on an average 3- 4%, which reached 10-20%.

® Risk groups ° Immunocompromised patients (e.g. AIDS patients) ° Infants and younger children in day-care centers ° Those whose drinking water is unfiltered and untreated ° Involved in farming practices such as lambing, calving, and muck-spreading ° Patients in a nosocomial setting with other infected patients or health-care employees ° Veterinarians who Prof.come Muhammad in contact Akram, with farm animals 1/7/2014 Cryptosporidium 3 ® Transmission is usually fecal-oral , often through water contaminated by livestock mammal feces. C. parvum can also be transmitted by following routes ° Food and water ° Animal to person ° Person to person ° Aerosol (possible)

Prof. Muhammad Akram, 1/7/2014 Cryptosporidium 4 ® Myzozoa, ° Class , ° Order , ˛ Family Cryptosporidiidae, ≠ Genus - Cryptosporidium, ≠ Species - C. parvum ® Tyzzer named this in 1910 to signify that it is a sporozoon in which spores are indistinguishable or absent in the oocyst.

Prof. Muhammad Akram, 1/7/2014 Cryptosporidium 5 Cryptosporidium parvum has seven distinct developmental stages namely 1. Oocyst 2. Sporozoites 3. Trophozoite 4. Merozoites (Type -1 & 2) 5. Meront (Type 1& 2) 6. Macrogametes 7. Micro gametes

Prof. Muhammad Akram, 1/7/2014 Cryptosporidium 6 ® The life cycle of Cryptosporidium is complex; there are both sexual and asexual cycles, and there are six distinct developmental stages.

® However, The parasite passes its entire life cycle within a single host. The life cycle is as follows :

Prof. Muhammad Akram, 1/7/2014 Cryptosporidium 7 Prof. Muhammad Akram, 1/7/2014 Cryptosporidium 8 Life cycle at a glance 3 types of life cycle - 1. Sexual, 2. Asexual 3. Autoinfection Stages of life cycle – Oocysts (Thick walled & Thin walled), Sporozoites, Trophozoite Type-1 & Type 2 Meronts, Merozoites, Microgametocytes, Macrogamont, Zygote. Steps of life cycle - 1.Ingestion of thick walled oocysts 2. Excystation in the small intestine with the release of four sporozoites 3.Invasion of intestinal epithelial cells 4.Sporozoite differentiates into trophozoite 5.Trophozites develops into type 1 meront (6-8 nuclei) & type2 meront (4 nuclei) 6.Type 1 meront gives rise to merozoites that infects new intestinal epithelial cells or develops either into type 1 or type 2 meronts 7.Type 2 meront differentiates into microgametocyte and macrogamont 8.Microgametocyte differentiates into microgamete and fertilized macrogamont forming zygote 9.Zygote develops into two types of oocysts ( Thick walled & Thin walled) 10.Sporozoites from thin walledProf. Oocysts Muhammad autoinfects Akram, and sporozoites from 1/7/2014 Cryptosporidium 9 thick walled Oocysts pass with stool 1. Adherence to intestinal epithelial cells-

2. Direct invasion - Cryptosporidium parvum directly invade the intestinal epithelial cells.

3. Intracellular multiplication.

Prof. Muhammad Akram, 1/7/2014 Cryptosporidium 10 ® Upon oocyst excystation, four sporozoites are released which adhere their apical ends to the surface of the intestinal mucosa by a sporozoite - specific lectin adherence factor . After sporozoite attachment, the epithelial mucosa cells release cytokines that activate resident phagocytes. These activated phagocytic cells release soluble factors (histamine, serotonin, adenosine, prostaglandins, leukotrienes, and platelet-activating factor) that increase intestinal secretion of water and chloride and also inhibit absorption. These soluble factors act on various substrates, including enteric nerves and on the epithelial cells themselves. Consequently, epithelial cells are damaged by one of two models: ° Cell death is a direct result of parasite invasion, multiplication, and extrusion, or, ° Cell damage could occur through T cell-mediated inflammation, producing villus atrophy and crypt hyperplasia Prof. Muhammad Akram, 1/7/2014 Cryptosporidium 11 ® The parasite elicits a strong immunologic response in infected, immunocompetent individuals, antibodies against glycoproteins and other cell determinants are readily detectable. ® However, the protective nature of the antibodies remains uncertain; some indirect evidence suggests that presence of antibodies in the intestinal lumen provides a protective effect against initial C. parvum infection, but evidence is contradictory. ® Indirect evidence infers a protective effect provided by the immune response, since illness is often severe in the very young - where the immune system is incompletely developed, and in the immunocompromised. ® Immunosuppressive agents like the corticosteroids promote experimental infections. Animal studies have shown that CD4 T cells (the cells affected by HIV) and gamma-interferon both play roles in clearing the parasite from infected, immunocompetent individuals. Prof. Muhammad Akram, 1/7/2014 Cryptosporidium 12 ® The illness is acute, but self-limiting in immunocompetent victims, generally lasting for 8-~20 days. ° It is characterized by the onset of explosive, profuse, watery diarrhea, usually 1 to 2 weeks after exposure, (incubation periods may be as short as 2 days). ° Less frequent symptoms include abdominal cramps, nausea, vomiting and low-grade (<39C) fever. ° Some nonspecific symptoms (weight loss, malaise, myalgia, weakness, headache) may be present.

® In immunocompromised persons, the illness is much more severe. ° As many as 71 stools/day, and losses of up to 25 L/day of water have been described in immunocompromised patients and the illness may persist indefinitely. ° Symptom severity may wax and wane, which could be correlated to the intensity of oocysts shedding. Oocyst excretion is most intense during the first week, decreasing thereafter and generally ceasing when diarrhea ceases.

° It is also apparent that asymptomaticProf. Muhammad Akram, cases occur. 1/7/2014 Cryptosporidium 13 ® Principle : ° Laboratory diagnosis is based on detection of oocysts directly from stool samples by modified acid fast staining . ° For greatest sensitivity and specificity, Immunofluorescense microscopy is the method of choice (followed closely by enzyme immunoassays, ° Nucleic acid based techniques (PCR) are also used.

Prof. Muhammad Akram, 1/7/2014 Cryptosporidium 14 ® There is no reliable treatment for cryptosporidium enteritis – ® certain agents such as paromomycin, atovaquone , nitazoxanide, and azithromycin are sometimes used but they usually have only temporary effects. ® Currently the best approach is to improve the immune status in immunodeficient individuals (such by using as antiviral therapy in-patients with AIDS) in addition to supportive treatment for symptoms. Prof. Muhammad Akram, 1/7/2014 Cryptosporidium 15 ® Washing hands is the most effective means of preventing transmission. ® For the immunocompromised, sex, including oral sex that involves possible contact with stool should be avoided. ® Immunocompromised individuals should also avoid the stool of all animals and wash their hands thoroughly after any contact with animals or the living areas of animals. ® Immunocompromised persons may also wish to wash, peel, or cook all vegetables and to take extra measures, such as boiling or filtering their drinking water, to ensure its safety.

Prof. Muhammad Akram, 1/7/2014 Cryptosporidium 16 1. Cryptosporidium parvum is a coccidian protozoal parasite, gaining much importance as a cause of diarrhea in immunocompromised persons in recent years.

2. C. parvum has 3 types of life cycle – sexual, asexual and autoinfection. It has several stages in its life cycle- Oocysts (Thick walled & thin walled), Sporozoites, Trophozoite Type - 1 & Type 2 Meronts, Merozoites, Microgametocytes, Macrogamont, Zygote.

3. C. parvum causes Cryptosporidiosis which is manifested by explosive, profuse, watery diarrhea, which is much more severe in immunocompromised persons.

4. Diagnosis of Cryptosporidiosis is based on detection of oocysts directly from stool samples by modified acid fast staining Direct fluorescent antibody test, EIA and PCR are also helpful.

5. There is no effective treatment for Cryptosporidiosis. Prof. Muhammad Akram, 1/7/2014 Cryptosporidium 17 1. What is the clinical significance of Cryptosporidium parvum in recent years? Why it is so named?

2. Describe peculiarities of morphology and life cycle of Cryptosporidium parvum

3. Write about the laboratory diagnosis of Cryptosporidiosis .?

4. Write about the pathogenesis of Cryptosporidiosis . Prof. Muhammad Akram, 1/7/2014 Cryptosporidium 18