ASCARIDS, AND As with other ascarids, eggs are excreted in and must develop PROCYONIS externally, typically in , to become infectious. When ingest infective eggs, larvae will hatch, enter the wall of the small (2 CE Hours) intestine and subsequently develop to adult in the small bowel. However, of eggs by other , especially Learning objectives rodents and other small mammals, results in extraintestinal migration ! List the risk factors for ascarids, hookworms and Baylisascaris of larvae; an estimated 5-7 percent of larvae invade the brain. The procyonis infections. migration of helminth larvae through tissue in suboptimal hosts ! Explain how and where humans and animals can become is termed migrans and may affect the viscera (visceral larva infected. migrans [VLM]), the eye (ocular larva migrans [OLM]), or the ! Explain how to diagnose, treat and prevent infection. nervous system (neural larva migrans [NLM]). Raccoons may also ! Describe the life cycle of these parasites. become infected when they eat larvae that have become encapsulated ! List recommendations you can provide to pet owners about in the tissues of rodents and other animals. treatment and prevention. ! List the contraindications when prescribing for More than 90 of wild and domesticated animals have been ascarids and hookworm. identifi ed as infected with B. procyonis larvae. Outbreaks of fatal central nervous system disease caused by B. procyonis have occurred Introduction on farms and in zoos and research colonies and have affected Happy and healthy animals are the goals of any veterinarian. It is commercial chickens, bobwhite quail, guinea pigs, commercial important to make sure that not only pets are protected from harm pheasants and domestic rabbits. Natural infections have also been but also that they do not pose a risk to others. Wildlife, our domestic recognized in , rodents, porcupines, chinchillas, prairie dogs, pets and humans are all susceptible to contracting and spreading primates, woodchucks, emus, and weasels. Experimental commonly found parasites. It is important to recognize, treat and infection of a variety of nonhuman primates has also been reported. prevent these infections so that they do not spread to a greater population. The prevalence of these infections varies with climatic conditions, but they are present in all parts of the and must be Common parasites viewed as a potential public health hazard. Ascarids (, T. cati) and hookworms ( spp.) are common intestinal parasites of dogs and (referred to Zoonotic and human disease here as pets). Not only can ascarids and hookworms cause disease The growing popularity of dogs and cats in the United States as in their respective hosts, they are also well-known causes of larva well as high rates of ascarid and hookworm infections have resulted migrans syndromes in humans, especially children. While ascarids in widespread contamination of the soil with infective eggs and and hookworms are most commonly diagnosed in puppies and larvae. Epidemiologic studies have implicated the presence of dogs, kittens, infections can occur in dogs and cats of all ages. Dogs can particularly puppies, in a household, and (dirt eating) as the also become infected with , the common principal risk factors for human disease. Children’s play habits and ascarid, which can cause serious disease in other animals their attraction to pets put them at higher risk for infection than and humans.1 adults. Ascarids – Because of the occurrence of both transplacental and Humans become infected with ascarids (Toxocara spp., Baylisascaris transmammary transmission of T. canis, puppies are usually born spp.) through ingestion of infective eggs in the environment. When with or acquire ascarid infections early in life.2 Kittens do not a human ingests infective eggs, the eggs hatch and release larvae become infected in utero, but like puppies, can acquire ascarids that can migrate anywhere in the body, a condition known as (T. cati) through the queen’s .3 The tissue-migrating and early . The seen in humans are intestinal stages of these worms may cause severe, sometimes determined by the tissues or organs damaged during larval migration. life-threatening, disease in the fi rst few weeks of life. Patent Organs commonly affected are the eye, brain, and , where intestinal infections can develop within the fi rst 2½-3 weeks of life. infections can cause permanent visual, neurologic or other tissue Left untreated, this can lead to widespread contamination of the damage. The common ascarid T. canis has long been recognized environment with infective eggs. as a cause of larva migrans syndromes in children. The ascarid T. cati can also cause disease in humans, although for reasons partly Hookworms – Both puppies and kittens acquire hookworm related to the defecation habits of cats, it does so less frequently. The infections (A. caninum, A. braziliense, and A. tubaeforme) through raccoon ascarid B. procyonis is increasingly being recognized as a ingestion of or penetration by infective larvae, or from infective cause of human disease.10 larvae passed in their dam’s milk (A. caninum).2 Hookworms suck large amounts of from their hosts, and while infected animals Humans can become infected with hookworms through ingestion 7 may look healthy in the fi rst week of life, they can develop a rapidly of infective larvae or through direct penetration of the skin. When severe, often fatal, .4 Patent intestinal infections can occur infective larvae penetrate the skin, they undergo a prolonged as early as 2 weeks (dogs) to 3 weeks (cats) of age, leading to migration that causes a condition known as . environmental contamination with infective larvae.5,6 These larval migrations are characterized by the appearance of progressive, intensely pruritic, linear eruptive lesions, which are Baylisascaris procyonis, a ubiquitous roundworm infection of usually more extensive with A. braziliense infections. A. caninum raccoons (Procyon lotor), is increasingly being recognized as a larvae may also penetrate into deeper tissues and induce symptoms cause of severe human disease. B. procyonis has a widespread of visceral larva migrans, or migrate to the intestine and induce an geographic distribution, with infection rates as high as 70 percent eosinophilic enteritis.11,12 in adult raccoons and exceeding 90 percent in juvenile raccoons. Although relatively few human cases of baylisascariasis have been reported, several factors suggest that the likelihood of exposure and 1 infection may be greater than is currently recognized. Raccoons Life cycle (intestinal ) have a widespread geographic distribution, and infection with B. procyonisis is common in raccoon populations, with typically high prevalence rates observed. An infected raccoon can harbor numerous adult worms and may excrete large numbers of eggs. A single adult female may produce an estimated 115,000 to 877,000 eggs per day, and an infected raccoon can shed as many as 45 million eggs daily. In light of the relatively low infectious dose of B. procyonis (estimated to be less than 5,000 eggs) and the viability of the eggs in the environment for months to years, the infection potential is not insubstantial. Raccoons have increasingly become peridomestic animals living in close proximity to human residences and are among the fastest growing wildlife populations nationwide. These animals benefi t from feeding on abundant pet left accessible, either accidentally or intentionally, and their populations can thrive under such conditions. In one suburban area near the residence of a recent patient in northern California, the raccoon population was measured at 30 animals per quarter-acre. Areas frequented by raccoons and used for defecation were found in close proximity to human dwellings, and B. procyonis eggs are routinely recovered from these areas. Children, particularly toddlers, may be at particular risk of Eggs are passed in the stool q, and under favorable conditions exposure. (moisture, warmth, shade), larvae hatch in one to two days. The released rhabditiform larvae grow in the feces and/or the soil, and Although baylisascariasis may indeed be underdiagnosed, after 5 to 10 days (and two molts) they become fi lariform (third- asymptomatic human infection may be the typical response, and the stage) larvae that are infective e. These infective larvae can survive limited number of cases reported may indicate that an unrecognized three to four weeks in favorable environmental conditions. On immune defect is necessary for severe infection to occur. The contact with the human host, the larvae penetrate the skin and are prevalence of asymptomatic infection in human populations has yet carried through the blood vessels to the heart and then to the . to be determined. They penetrate into the pulmonary alveoli, ascend the bronchial tree In an era of increasing concern about bioterrorism, certain to the pharynx and are swallowed r. The larvae reach the small characteristics of B. procyonis make it a feasible bioterrorist agent. intestine, where they reside and mature into adults. Adult worms live The organism is ubiquitous in raccoon populations and therefore in the lumen of the , where they attach to the intestinal easy to acquire. Enormous numbers of eggs can be readily obtained, wall with resultant blood loss by the host t. Most adult worms are and these eggs can survive in an infectious form for prolonged eliminated in one to two years, but the longevity may reach several periods of time. As with other ascarids, the eggs can remain viable years. in a dilute (0.5 percent-2 percent) formalin solution for an indefi nite Some A. duodenale larvae, following penetration of the host skin, period of time, and animal studies suggest that B. procyonis has a can become dormant (in the intestine or muscle). In addition, relatively small infectious dose. Moreover, the organism causes a infection by A. duodenale may probably also occur by the oral severe, frequently fatal infection in humans, and no effective therapy and transmammary route. N. americanus, however, requires a or exists. Introduction of suffi cient quantities of B. procyonis transpulmonary migration phase. eggs into a water system or selected food products could potentially result in outbreaks of the infection. A similar agent, suum, a Life cycle (cutaneous larval migrans) roundworm of pigs, was used to intentionally infect four university students who required hospitalization after eating a meal that had been deliberately contaminated with a massive dose of eggs. Contamination of community water sources would be diffi cult since the eggs of B. procyonis are relatively large (80 μm long by 65 μm wide) and would be readily removed by standard fi ltration methods or the fl occulation and sedimentation techniques used by municipal water systems in the United States. However, post-treatment contamination or targeting of smaller systems could be possible.

Causal agents The human hookworms include the species, and . A larger group of hookworms infecting animals can invade and parasitize humans (A. ceylanicum) or can penetrate the (causing cutaneous larva migrans), but do not develop any further (A. braziliense, A. caninum, ). Occasionally A. caninum larvae may migrate to the human intestine, causing eosinophilic enteritis. larvae have also been implicated as a cause of diffuse unilateral subacute neuroretinitis.

2 Cutaneous larval migrans (also known as creeping eruption) is a Life cycle zoonotic infection with hookworm species that do not use humans as a defi nitive host, the most common being A. braziliense and A. caninum. The normal defi nitive hosts for these species are dogs and cats. The cycle in the defi nitive host is very similar to the cycle for the human species. Eggs are passed in the stool q, and under favorable conditions (moisture, warmth, shade), larvae hatch in 1 to 2 days. The released rhabditiform larvae grow in the feces and/ or the soil w, and after fi ve to 10 days (and two molts) they become fi lariform (third-stage) larvae that are infective e. These infective larvae can survive three to four weeks in favorable environmental conditions. On contact with the animal host r, the larvae penetrate the skin and are carried through the blood vessels to the heart and then to the lungs. They penetrate into the pulmonary alveoli, ascend the bronchial tree to the pharynx and are swallowed. The larvae reach the small intestine, where they reside and mature into adults. Adult worms live in the lumen of the small intestine, where they attach to the intestinal wall. Some larvae become arrested in the tissues, and serve as source of infection for pups via transmammary (and possibly transplacental) routes t. Humans may also become infected when fi lariform larvae penetrate the skin y. With most species, the larvae cannot mature further in the human host, and migrate aimlessly within the epidermis, sometimes as much as several centimeters a day. Some larvae may persist in deeper tissue after fi nishing their skin migration.

Geographic distribution Adult worms q live in the lumen of the small intestine. A female Hookworm is the second most common human helminthic infection may produce approximately 200,000 eggs per day, which are passed (after ). Hookworm species are worldwide in distribution, with the feces w. Unfertilized eggs may be ingested but are not mostly in areas with moist, warm climate. Both N. americanus and infective. Fertile eggs embryonate and become infective after 18 A. duodenale are found in Africa, Asia and the . Necator days to several weeks e, depending on the environmental conditions americanus predominates in the Americas and Australia, while only (optimum: moist, warm, shaded soil). After infective eggs are A. duodenale is found in the , and southern swallowed r, the larvae hatch t, invade the intestinal mucosa and Europe. are carried via the portal, then systemic circulation to the lungs y. The larvae mature further in the lungs (10 to 14 days), penetrate Causal agent the alveolar walls, ascend the bronchial tree to the throat, and are is the largest nematode (roundworm) swallowed u. Upon reaching the small intestine, they develop into parasitizing the human intestine. (Adult females: 20 to 35 cm; adult adult worms q. Between two and three months are required from male: 15 to 30 cm.) ingestion of the infective eggs to oviposition by the adult female. Adult worms can live one to two years. The public health problem Larva migrans syndromes are not reportable in the United States, so the actual number of human cases is unknown. However, many human cases continue to be diagnosed, and a recent national survey of shelters revealed that almost 36 percent of dogs nationwide and 52 percent of dogs from southeastern states harbored helminths capable of causing human disease.13 Every year at least 3,000-4,000 serum specimens from patients with presumptive diagnoses of are sent to the Centers for Disease Control and Prevention (CDC), state public health laboratories, or private laboratories for serodiagnostic confi rmation.14 Zoonotic hookworm infections are more geographically restricted than toxocariasis, with most cutaneous larva migrans and other hookworm-associated syndromes diagnosed in southeastern and Gulf Coast states. Persons likely to come in contact with larvae-contaminated soil include electricians, plumbers and other workers who crawl beneath raised buildings; sunbathers who recline on larvae-contaminated ; and children who play in contaminated areas. While most hookworm infections are self-limiting, massive infections can lead to infection of deeper tissues.15

3 Outbreak in Miami summer camp Approximately 40.9 percent attended for two weeks, and 27.3 On July 19, 2006, the director of a children’s aquatic sports day camp percent attended for more than six weeks. At the time interviews notifi ed the Miami-Dade County Health Department (MDCHD) were conducted (July 19-Sept. 2), six (27.3 percent) of the 22 of three campers who had received a diagnosis of cutaneous larva patients were still attending the camp, and 18 (81.8 percent) were migrans (CLM), or “creeping eruption,” a skin condition typically still experiencing symptoms. All 22 patients participated in the half- caused by dog or cat hookworm larvae of the Ancylostoma. day camp for children aged 2-6 years. Although campers and staff MDCHD conducted an investigation to determine the source and members for both the half-day and full-day camps were exposed magnitude of the outbreak and prevent additional illness. Although to sand from the beach and the volleyball court, only those in the CLM outbreaks are reported rarely to the Department of half-day camp were allowed in the playground area, which included Health, evidence indicates that CLM is a potential health hazard in a sandbox containing approximately 400 cubic feet of sand that Florida. This disease cluster highlights the importance of appropriate had been placed in the box two years previously. Campers were in environmental practices and education in preventing CLM. or around the sandbox for approximately one hour each day, and all campers wore bathing suits while in this area. Fourteen (63.7 The camp property, which is located in Miami, includes swimming percent) of the 22 who became ill did not wear shoes while sitting in pools and a main building, volleyball court, playground with a the sandbox. Four (18.2 percent) of the persons reported seeing cats sandbox, picnic area and beach for boating and swimming. The camp near the sandbox. consisted of four two-week sessions held from June 5-July 28, 2006, and was divided into two programs: a half-day session for children MDCHD investigators arrived at the site on July 19 to investigate aged 2-6 years, and a full-day session for children aged 5-15 years. the campgrounds and interview camp administrators. Camp Approximately 300 campers and 80 staff members attended each administrators had sectioned off the sandbox already to prevent session. children from using the area; the camp director had researched CLM online and identifi ed contaminated sandboxes as possible sources of On July 20, camp administrators announced to all current campers, infection. During their initial visit to the site, MDCHD investigators their parents and staff members that three children had received observed cats around the playground sandbox and noticed animal CLM diagnoses. Parents were asked to look for various symptoms feces inside the sandbox; no fecal samples were collected. Interviews of infection, including a snake-shaped (serpiginous) red rash, with the camp director revealed that general beach areas, to which all itching and pus-containing lesions. In addition, camp administrators campers in both age groups were exposed, were frequented by dogs; provided information about CLM to the households of any other therefore, the sand in general beach areas also was considered a campers and staff members who attended sessions during the possible source of exposure. Additional possible sources of exposure summer. MDCHD advised that persons with signs or symptoms seek considered included: medical care and contact the health department to make a report.  Pets at home (10 patients [45 percent], with eight dogs, one cat MDCHD received a total of 22 reports of persons (four staff and one unknown). members and 18 campers, including the three initial patients) with  Exposure to another nearby beach in the week before symptom signs or symptoms of CLM. To identify cases, MDCHD staff onset (nine [41 percent]). members conducted telephone interviews of these persons by  Shared personal items, such as towels or clothes with other using a 60-item questionnaire that collected information regarding campers (four [18 percent]). demographic variables, illness history and activity history. A case After analyzing initial data collected during July 19-25, MDCHD was defi ned as illness consistent with CLM in a staff member or suspected that the sandbox was the source of infection. Staff camper who attended the camp at any time during June 5-July 20, members inspected the camp again on July 26 and did not fi nd feces 2006, and had symptoms during June 5-Aug. 20. All 22 persons in the sandbox for laboratory testing. Immediately after the July 26 who reported signs or symptoms met the case defi nition. Although inspection, sand in the sandbox was removed and replaced. Two no laboratory samples were obtained, all 22 patients had received a feral cats were removed from the premises by animal control and clinical diagnosis of CLM. euthanized; the cats were not tested for hookworm. MDCHD staff MDCHD conducted a descriptive, cross-sectional study of the 22 recommended to camp administrators that the sandbox be covered cases and an environmental health assessment of the camp property. with a tarp when not in use to prevent fecal contamination and to Illness onset occurred during June 20-Aug. 1. The median age change the sand regularly in accordance with American Academy of campers was 4 years (range: 2-6 years); and the median age of Pediatrics and American Public Health Association standards. of staff members was 17 years (range: 16-19 years). Patients had Administrators also were advised to report stray animals to animal signs and symptoms including erythema (100 percent), pruritic control for removal and to inspect the sandbox daily and remove rashes (100 percent), serpiginous lesions (77.3 percent), changing feces to reduce the number of potentially infective larvae; larvae location of rash or lesions (50.0 percent), blistering lesions (27.3 typically do not emerge from their eggs in less than 24 hours. After percent), and pus-containing lesions (18.2 percent). Lesions were the interventions were implemented on July 26, three additional noted on the buttocks (68.2 percent), feet (45.5 percent), legs (27.3 cases were reported through Sept. 2; however, these persons might percent), hands (9.1 percent), groin (9.1 percent) and abdomen have been exposed before the interventions were in place. (4.5 percent). Nine (40.9 percent) of the patients had lesions in Preventive anthelmintic treatment more than one location either during a single episode or during the Because puppies, kittens and pregnant and nursing animals are at course of the infection. All but two patients used a nonprescription highest risk for these infections and therefore responsible for most topical ointment at home before seeking medical attention, and all of the environmental contamination and human disease, anthelmintic 22 patients sought medical attention. MDCHD contacted every treatments are most effective when they are initiated early and physician to confi rm CLM diagnoses. Patients were treated with targeted at these populations.4,15 thiabendazole, , or . While it has long been recognized that transplacental and The mean length of time patients were at the camp was 3.7 weeks. transmammary infection of ascarids and hookworms could be 4 prevented through prophylactic treatment of pregnant dogs, no drugs Table 1. Drugs for the treatment of ascarid and hookworm are currently approved for this use. However, the effectiveness of this infections in dogs and cats approach with different drugs approved for parasite control in dogs FDA Approved in: has been well documented. Daily treatment of pregnant dogs with Name Route of Range Species Minimum from the 40th day of gestation through the 14th day of Administration of Age/ lactation has been shown to inhibit T. canis larvae in tissues, thereby / Frequency / Effi cacy Weight preventing or greatly reducing the incidence of infection in puppies.19 Dose Alternatively, studies have shown that treatment with ivermectin on days 0, 30, 60 of gestation and 10 days post whelping reduced the Diethyl- Oral DI Dog ≥8 weeks adult T. canis worm burden in pups by 100 percent and prevented the carbamazine 6.6 mg/kg daily 1, 10 shedding of eggs.20 In yet another study, treatment with selamectin citrate 55-110 mg/kg A at 10 and 40 days both before and after parturition was effective in once; repeat in reducing T. canis fecal egg counts in both pups and their dams, and 10-20 days adult worms in the pups.21 Diethyl- Oral/daily A, H, W, Dog ≥8 weeks If the mother did not receive prophylactic treatment, puppies and carbamazine / 6.6 mg/kg DEC DI and ≥1 lb kittens must be treated early and repeatedly in order to prevent 5.0 mg/kg OXI patent infections.22 In areas where both ascarids and hookworms 1, 3, 4, 10 are common, begin treating both puppies and their mothers with an Fenbendazole Oral/daily for 3 A, H, Dog None age-appropriate anthelmintic at 2, 4, 6, and 8 weeks of age. Some days W, T recommend extending this to 12 weeks and then treating monthly 50 mg/kg until the pet is 6 months old. To treat for ascarids alone, begin by 2 Ivermectin4, 10 Oral/monthly H, DI Cat ≥6 weeks ½-3 weeks and treat every two weeks for at least three additional 24 μg/kg treatments. Because prenatal infection does not occur in kittens, preventive treatment should begin at 3 weeks of age, and be repeated Ivermectin Oral/monthly A, H, DI Dog ≥6 weeks at 5, 7, and 9 weeks. Nursing dogs and queens should be treated / 6 μg/kg IVM concurrently with their offspring because they often develop patent pamoate1, 7, 10 5 mg/kg PYR infections along with their young. Oral/monthly A, H, W, Dog ≥4 weeks oxime1, 4, 7, 10 Dog: 0.5 mg/kg DI and ≥2 lbs Because most puppies and kittens are not routinely brought to a veterinarian before 6-8 weeks of age, they will already have patent Cat: 2.0 mg/kg A, H, DI Cat ≥6 weeks infections and be actively contaminating the environment. For this and ≥1.5 reason, it is important to reach out to clients who have pregnant or lbs newly born animals at home, and provide these animals with early Milbemycin Oral/monthly A, H, W, Dog ≥4 weeks prophylactic treatment for intestinal parasites. Early identifi cation oxime / 0.5 mg/kg MO DI and ≥2 lbs of these high-risk animals will provide the veterinarian with the lufenuron1, 4, 10 mg/kg LUF opportunity to educate the owners on the public health risks, provide 7, 10, 11 them with an appropriate anthelmintic and advise them on how Moxidectin1, 4, SC/twice yearly H, DI Dog ≥6 months and when to administer it to their pets at home. This approach to 6, 10, 12 0.17 mg/kg treatment is justifi ed by the frequency with which puppies and 5 kittens acquire intestinal parasites from their mothers, and the Oral/ A Dog/cat ≥6 weeks diffi culties that exist in early diagnosis. Because young animals discretionary may continuously acquire new infections from nursing and from the See label for environment, they may develop a serious illness or even die before dose a prenatally or lactogenically acquired infection becomes patent and Pyrantel Oral/ A, H Dog ≥2 weeks can be diagnosed by fecal examination. pamoate14 discretionary 5 mg/kg While intestinal parasites are usually less of a problem in young adult and adult animals, they too can develop patent infections and Pyrantel Oral/ A, H, Cat ≥1 month contaminate the environment. Therefore, they too should be regularly pamoate / discretionary T, D and ≥1.5 4, monitored or treated for intestinal parasite infections. While all adult praziquantel 5 mg/kg PRA lbs 13 animals are at risk, those that are allowed to roam or spend most of 20 mg/kg PYR their time outside run a greater risk of becoming infected. There are Pyrantel Oral/ A, H, W, Dog ≥3 weeks a variety of anthelmintic drugs available that are safe and effective pamoate / discretionary T, D, E and ≥2 lbs against ascarids, hookworms and other intestinal helminths of dogs praziquantel / 5 mg/kg PYR and cats (Table 1). Mature animals can also be monitored through febantel2, 9 5 mg/kg PRA biannual or yearly diagnostic stool examinations and treated with 25 mg/kg FEB anthelmintics directed at specifi c intestinal . For animals Selamectin4, Topical/monthly Dog: DI Dog ≥6 weeks that live in areas where heartworm (Dirofi laria immitis) infection 7, 8, 10 6mg/kg Cat: A, Cat is enzootic, many of the heartworm preventives are also effective S H, DI against intestinal parasites (Table 1).23 A = ascarids (Toxocara and Toxascaris spp.) H = hookworm Ancylostoma and Uncinaria spp.) W = whipworm (Trichuris vulpis)

5 T = Taeniid tapeworms (Taenia pisiformis, Taenia taeniaeformis, their offspring can protect their pets from becoming infected, Taenia spp.) thus preventing them from shedding eggs into and contaminating D = Flea tapeworm (Dipylidium caninum) the environment. E = , Echinococcus multilocularis  The need for regular diagnostic fecal examinations of pups or DI = Dirofi laria immitis kittens or prophylactic treatment of older pets.  The need for prompt collection and disposal of pet feces, Contraindications: especially in areas where children play, to remove eggs from the 1Not for use in animals with established heartworm infections. environment before they can become a problem. 2Do not use in pregnant animals.  The need to keep children away from areas that may be 3Do not use in dogs with hepatic dysfunction. contaminated with pet feces. 4Not effective against Uncinaria. 5Some salts not for use in unweaned animals. Additional information for clients 6See package insert for injection technique. Below is basic information that you can put into a brochure to give 7Safe in collies at label dose. to your clients. 8Also effective against fl eas, fl ea eggs, ticks, and mites (including ear What is hookworm? mites). Hookworm is an intestinal parasite of humans that causes mild 9Repeat every 21-26 days for control of Echinococcus multilocularis. and . Heavy infection with hookworm can 10Effective against tissue stage of heartworm larvae. create serious health problems for newborns, children, pregnant 11 Not a fl ea adulticide – contains an insect growth regulator. women and persons who are malnourished. Hookworm infections 12Effective against hookworm larvae and adults at time of injection occur mostly in tropical and subtropical climates. In 2002, the only. estimated number of person infected with hookworm was 1.3 billion. 13Consult with veterinarian before using in pregnant animals. 14Approved for use in lactating dogs (administer 2-3 weeks after Where are hookworms commonly found? parturition). The geographic distributions of the hookworm species that are intestinal parasites in humans, Ancylostoma duodenale (an-cy-CLO- Veterinarians can help prevent human disease sto-ma doe-AH-den-al) and Necator americanus (ne-KAY-tor am- Most cases of human ascarid and hookworm infections can be er-i-CON-us), are worldwide in areas with warm, moist climates, prevented by practicing good personal hygiene, eliminating and widely overlapping. Necator americanus was widespread in the intestinal parasites from pets through regular and making Southeastern United States early in the 20th century. The Rockefeller potentially contaminated environments, such as unprotected sand Sanitary Commission was founded in response, and hookworm boxes, off limits to children.9,10,14 It is also important to clean up pet infection in this area was well controlled. feces on a regular basis to remove potentially infective eggs before they become disseminated in the environment via , insects or the Hookworm eggs are not infective; they release larvae in soil that active migration of the larvae.16 Hookworm eggs can develop into have the ability to penetrate the skin. Hookworm infection is infective stage larvae in the soil in as little as fi ve days, and ascarid transmitted primarily by skin being in contact with soil (for example, eggs within two weeks, depending on temperature and humidity.4 To by walking ) but can also be transmitted through the illustrate the extent of environmental contamination that can occur as ingestion of larvae. the result of one infected puppy, a single female ascarid can produce How do I get a hookworm infection? more than 100,000 eggs per day, resulting in millions of potentially You can become infected by direct contact with contaminated soil, infective ascarid eggs per day spread throughout the area the puppy generally through walking barefoot or accidentally swallowing is allowed to roam.10 Once the eggs become infective, they can contaminated soil. remain infective in the environment for years.4,10 Hookworms have a complex life cycle that begins and ends in the Most pet owners do not know that their pets may carry worms small intestine. Adult female worms produce thousands of eggs, capable of infecting people. Therefore, practicing veterinarians which are excreted in stool. Hookworm eggs are not themselves can provide an important public service by recommending regular infective. However, if they reach soil (for example, when infected fecal examinations, providing well-timed anthelmintic treatments, persons defecate on the ground or when “night soil” is used to counseling clients on potential public health hazards and advising fertilize crops) and if the soil conditions are favorable (warm, moist, them on any precautionary measures that may be undertaken. and shaded), the eggs hatch into larvae. The barely visible larvae Veterinarians are in an ideal position to provide pet owners with penetrate the skin (often through bare feet), are carried to the lungs, this service because of their access to the pet-owning public, their go through the respiratory tract to the mouth, are swallowed and knowledge and training and their role in the human-animal bond. eventually reach the small intestine. This journey takes about a week. Educating and counseling pet owners In the small intestine, the larvae develop into half-inch-long worms, Pet owner education regarding intestinal parasites and their effects attach themselves to the intestinal wall and suck blood. on the health of both their pets and family members should be Who is at risk? included in a well-pet exam. Pet owner education should focus on People who have direct contact with soil that contains human feces prevention and include the following: in areas where hookworm is common are at high risk of infection.  Description of ascarids and hookworms that infect dogs and Children – because they play in dirt and often go barefoot – are at cats, early signs of illness, and when pets are at greatest risk for high risk, although the prevalence of hookworm infection in endemic infection (in utero and when nursing). countries continues to rise into young adulthood. Since transmission  How ascarids and hookworms cause disease in humans, of hookworm infection requires development of the larvae in soil, especially in children whose play habits and attraction to pets put hookworm is not spread person to person. Contact among children them at increased risk.  How prophylactic treatment of pregnant and nursing pets and 6 in institutional or child-care settings should not increase the risk of ASCARIDS, HOOKWORMS AND infection. BAYLISASCARIS PROCYONIS What are the symptoms of hookworm? Final Examination Questions Itching and a rash at the site of where skin touched soil and is usually the fi rst sign of infection. These symptoms occur when the larvae Choose true or false for each question and complete your test online penetrate the skin. While a light infection may cause no symptoms, at www.veterinarianCE.com. heavy infection can cause anemia, abdominal pain, diarrhea, loss of appetite and weight loss. Heavy, chronic infections can cause stunted 1. Kittens, like puppies, can become infected with ascarids in utero. growth and mental development. Can a hookworm infection cause any serious health problems? True False Yes. The most serious results of hookworm infection are the development of anemia and protein defi ciency caused by blood loss. When children are continuously infected by many worms, the 2. Certain characteristics of B. procyonis make it a feasible loss of and protein can retard growth and mental development, bioterrorist agent. sometimes irreversibly. Hookworm infection can also cause tiredness and diffi culty breathing with exertion. Severe disease can cause True False congestive .

What should I do if I think I have a hookworm infection? 3. Children are more susceptible to ascarid and hookworm infection Visit your health care provider. Infection is diagnosed by identifying than adults because their play habits and attraction to pets put hookworm eggs in a stool sample. them at increased risk. What is the treatment for hookworm? Hookworm infections are generally treated for 1-3 days with True False prescribed by your health care provider. The drugs are effective and appear to have few side effects. Your health care provider may decide to repeat a stool exam after treatment. Iron 4. Puppies, kittens and pregnant and nursing animals are at highest supplements may be prescribed if you have anemia. risk for hookworm and ascarid infection.

How can I prevent hookworm? True False Do not walk barefoot or contact the soil with bare hands in areas where hookworm is common or where there may be fecal contamination of the soil. 5. Hookworm eggs can develop into infective stage larvae in the soil in as little as two days. References 1. Samuel WM, Pybus MJ, Kocan AA. Parasitic diseases of wild mammals. Second ed. Ames: Iowa State True False University Press. 2001;301-41. 2. Burke TM, Roberson EL. Prenatal and lactational transmission of Toxocara canis and Ancylostoma caninum: experimental infection of the bitch before pregnancy. Int J Parasitol 1985;15:71-5. 3. Swerzcek TW, Nielsen SW, Helmbolt CF. Transmammary passage of Toxocara cati in the cat. Am J Vet Res 1971;32:89-92. 4. Bowman DD. Georgis’ parasitology for veterinarians. Seventh ed. Philadelphia: WB Saunders Company. 1999;178-84. 5. Hendrix CM, Homer SB, Kellman NJ, Harrelson G, Bruhn BF. Cutaneous larva migrans and enteric hookworm infections. J Am Vet Med Assoc 1996; 209(10):1763-76. 6. Kalkofen VP. Hookworms of dogs and cats. Vet Clin North Am Small Anim Pract 1987;17:1341-54. 7. Glickman LT, Schantz PM. Epidemiology and pathogenesis of zoonotic toxocariasis. Epidemiol Rev 1981;3:230-50. 8. Parsons JC. Ascarid infections in cats and dogs. Vet Clin North Am Small Anim Pract 1987;17:1307-39. 9. Kazacos KR. Visceral and ocular larva migrans. Semin Vet Med Surg (Small Anim) 1991;6:227-35. 10. Kazacos KR. Protecting children from helminthic . Contemp Pediatr 2000;17(3)(Suppl):1-24. 11. Little MD, Halsey NA, Cline BL, Katz SP. Ancylostoma larva in muscle fi ber of man following cutaneous larva migrans. Am J Trop Med Hyg 1983;32:1285-8. 12. Prociv P, Croese J. Human eosinophilic enteritis caused by dog hookworm Ancylostoma caninum. Lancet 1990;335:1299-1302. 13. Blagburn BL, Lindsay DS, Vaughan JL, et al. Prevalence of canine parasites based on fecal fl otation. Comp Contin Educ Vet Pract 1996;18:483-509. 14. Schantz PM. Toxocara larva migrans now. Am J Trop Med Hyg 1989;41(3)(Suppl):21-34. 15. Schantz PM. Zoonotic ascarids and hookworms: The role for veterinarians in preventing human disease. Compendium on continuing education for the practicing veterinarian 2002;24(1) (Suppl):47-52. 16. Beaver PC. Biology of soil-transmitted helminths: The massive infection. H. L. S. 1974;12(2):116-25. 17. Harvey JB, Roberts JM, Schantz PM. Survey of veterinarians’ recommendations for the treatment and control of intestinal parasites in dogs: Public health implications. J Am Vet Med Assoc 1991;199:702-7. 18. Barriga OO. Rational control of canine toxocariasis by the veterinary practitioner. J Am Vet Med Assoc 1991;198:216-21. 19. Duwel D, Strasser H. of helminth-free canine pups through maternal fenbendazole therapy. Dtsch Tierarztl Wochenschr 1978;85(6):239-41. 20. Payne PA, Ridley RK. Strategic use of ivermectin during pregnancy to control Toxocara canis in greyhound puppies. Vet Parasitol 1999;85(4):305-12. 21. Payne-Johnson M, Maitland TP, Sherington J, Shanks DJ, Cements PJ, Murphy MG, McLoughlin A, Jernigan AD, Rowan TG. Effi cacy of selamectin administered topically to pregnant and lactating female dogs in the treatment and prevention of adult roundworm (Toxocara canis) infections and fl ea (Ctenocephalides felis felis) in the dams and their pups. Vet Parasitol 2000;91(3-4):347-58. 22. Stoye M. Biology, pathogenicity, diagnosis and control of Ancylostoma caninum. Dtsch Tierarztl Wochenschr 1992;99(8):315-21. 23. Reinemeyer CR, Faulkner CT, Assadi-Rad AM, Burr JH, Patton S. Comparison of the effi cacies of three heartworm preventatives against experimentally induced infections with Anycylostoma caninum and Toxocara canis in pups. J Am Vet Med Assoc 1995;206(11):1710-5. 24. http://www.cdc.gov/ncidod/eid/vol8no4/01-0273.htm 7