sign in sign up
<<
Home , Ancylostomatidae, Hookworm infection, Uncinaria stenocephala

(1 CE Hour) Learning objectives !! List the risk factors for infections. !! Explain how and where humans and can become infected. !! Explain how to diagnose, treat and prevent . !! Describe the life cycle of these parasites. !! List recommendations you can provide to pet owners about treatment and prevention. !! List the contraindications when prescribing for hookworm.

Introduction Zoonoses are infectious diseases that can be transmitted from animals to humans, most likely when animals and human beings are in close contact. Causative groups of agents include parasites, fungi, bacteria, viruses. Usually of minor importance, they nevertheless can lead to severe disease, especially in the very young and those with certain conditions, and to death, particularly with certain viral diseases (such as rabies, hemorrhagic fevers, encephalitis). Hookworms exist worldwide and Life cycle (Intestinal hookworm infection) cross from carnivorous animals to man in all Eggs are passed in the stool , and under favorable conditions (moisture, warmth, shade), larvae parts of the world. hatch in one to two days. The released rhabditiform larvae grow in the feces and/or the soil , and  The parasite after 5 to 10 days (and two molts) they become filariform (third-stage) larvae that are infective . These infective larvae can survive three to four weeks in favorable environmental conditions. On Hookworms belong to the family of contact with the human host, the larvae penetrate the skin and are carried through the vessels to which are part of the the heart and then to the . They penetrate into the pulmonary alveoli, ascend the bronchial tree to Phylum of : caninum the pharynx and are swallowed . The larvae reach the small intestine, where they reside and mature and A. braziliense (, fox, coyote, other into adults. Adult worms live in the lumen of the small intestine, where they attach to the intestinal carnivores, human), A. tubaeforme () and stenocephala (cat, dog, fox). The wall with resultant blood loss by the host . Most adult worms are eliminated in one to two years, adult stage is small, 1-2 cm long, with the but the longevity may reach several years. Some A. duodenale larvae, following penetration of the females slightly larger, usually located in the host skin, can become dormant (in the intestine or muscle). In addition, infection by A. duodenale small intestine. They will produce eggs with may probably also occur by the oral and transmammary route. N. americanus, however, requires a clear, translucent shells, developing quickly in transpulmonary migration phase. a warm and moist environment to blastomeres Symptomatology and diagnosis Zoonotic and human disease and within two (2) days to three (3) weeks – Adult having chronic hookworm infection The growing popularity of dogs and depending on temperature and humidity – to may have no symptoms at all. Indications of in the as well as high rates of infective larvae (Table 1). the disease are weakness, listlessness, hookworm infections have resulted in widespread Both puppies and kittens acquire hookworm (pale mucosae, gingiva), rough fur coat and contamination of the soil with eggs and infective infections through ingestion or skin penetration often, with black/bloody feces. Another larvae. Epidemiologic studies have implicated by infective larvae or from infective larvae expression is eosinophilic enteritis produced the presence of dogs, particularly puppies, in a passed in utero or with their dam’s milk. by intestinal infection resulting in household, and (dirt eating) as the principal Hookworms suck large amounts of blood and . Live larvae can be found in risk factors for human disease. Children’s play from their hosts, and while infected animals feces of affected animals. Eggs in the feces can habits and their attraction to pets put them at may look healthy in the first weeks of life, be identified microscopically following standard higher risk for infection than adults, and their they can develop a rapidly severe, often fatal, flotation procedures over 33 percent zinc sulfate. symptoms are more severe. Humans can become anemia. Open intestinal infections can appear as However, there may be a lag of several weeks infected with hookworms through ingestion of early as 2 weeks (dogs) to 3 weeks (cats) of age, between infection and the deposition of eggs, so infective larvae or through direct penetration of leading to environmental contamination with that the absence of eggs does not imply absence the skin. When infective larvae penetrate the skin, infective larvae. of the disease. Egg counts are important to they undergo a prolonged migration that causes determine the effect of treatment. a condition known as cutaneous migrans. Table 1 A.caninum A.braziliense A.tubaeforme U.stenocephale Adult male (mm) 11-13 x 0.34-0.39 5-7.5 x 0.19-0.27 9.5-11 x 0.3-0.35 5 - 9 x 0.2 Adult female (mm) 14-20.5 x 0.50-0.56 6.5-10.6 x 0.22-0.32 12 – 15 x 0.38 – 0.43 7 – 13 x 0.2 – 0.25 Oval eggs(micron) 56 - 75 x 34 - 47 75 - 95 x 41 - 45 55 - 78 x 34 - 45 63 – 76 x 32 - 38 Teeth 6 + 2 4 6 Cutting plates Hosts Dog, fox, coyote, other Dog, cat, fox, other Felines Dog, cat, fox, other carnivores; humans carnivores; humans carnivores; humans

Elite Page 1 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.

Outbreak in a Miami summer camp On July 19, 2006, the director of a children’s aquatic sports day camp notified the Miami- Dade County Health Department (MDCHD) of three campers who had received a diagnosis of (CLM), or “creeping eruption,” a skin condition typically caused by dog or cat hookworm larvae of the genus Ancylostoma. MDCHD conducted an investigation to determine the source and magnitude of the outbreak and prevent additional illness. Although CLM outbreaks are reported rarely to the Department of Health, evidence indicates that CLM is a potential health hazard in Florida. This disease cluster highlights the importance of appropriate environmental practices and education in preventing CLM. Life cycle (Cutaneous larval migrans) The camp property, which is located in Miami, Cutaneous larval migrans (also known as creeping eruption) is a zoonotic infection with hookworm includes swimming pools and a main building, species that do not use humans as a definitive host, the most common beingA. braziliense and A. volleyball court, playground with a sandbox, caninum. The normal definitive hosts for these species are dogs and cats. The cycle in the definitive picnic area and beach for boating and swimming. host is very similar to the cycle for the human species. Eggs are passed in the stool , and under The camp consisted of four two-week sessions favorable conditions (moisture, warmth, shade), larvae hatch in 1 to 2 days. The released rhabditiform held from June 5-July 28, 2006, and was divided into two programs: a half-day session for children larvae grow in the feces and/or the soil , and after five to 10 days (and two molts) they become aged 2-6 years, and a full-day session for children filariform (third-stage) larvae that are infective . These infective larvae can survive three to four aged 5-15 years. Approximately 300 campers and weeks in favorable environmental conditions. On contact with the host , the larvae penetrate 80 staff members attended each session. 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 On July 20, camp administrators announced reach the small intestine, where they reside and mature into adults. Adult worms live in the lumen to all current campers, their parents and staff of the small intestine, where they attach to the intestinal wall. Some larvae become arrested in the members that three children had received tissues, and serve as a source of infection for pups via transmammary (and possibly transplacental) CLM diagnoses. Parents were asked to look routes . Humans may also become infected when filariform larvae penetrate the skin . With for various symptoms of infection, including most species, the larvae cannot mature further in the human host, and migrate aimlessly within the a snake-shaped (serpiginous) red rash, itching epidermis, sometimes as much as several centimeters a day. Some larvae may persist in deeper tissue and pus-containing lesions. In addition, camp after finishing their skin migration. administrators provided information about CLM to the households of any other campers and These larval migrations are characterized by the parts of the U.S, Central and South America). By staff members who attended sessions during the appearance of progressive, intensely pruritic, contrast, U. stenocephala is found in northern summer. MDCHD advised that persons with linear eruptive lesions, which are usually more climates (Canada, the northern U.S. and Europe). signs or symptoms seek medical care and contact extensive with A. braziliense infections. A. Both N. americanus and A. duodenale are found the health department to make a report. caninum larvae may also penetrate into deeper in Africa, Asia and the . N. americanus tissues and induce symptoms of visceral larva MDCHD received 22 reports of persons (four predominates in the Americas and Australia, migrans, or migrate to the intestine and induce staff members and 18 campers, including the while only A. duodenale is found in the Middle eosinophilic enteritis. Hookworms penetrating the three initial patients) with signs or symptoms of East, and . (causing cutaneous larva migrans) CLM. To identify cases, MDCHD staff members usually do not develop any further or mature (A. conducted telephone interviews of these persons The public health problem by using a 60-item questionnaire that collected braziliense, A. caninum, ). Larva migrans syndromes are not reportable in larvae have also been information regarding demographic variables, the United States, so the actual number of human illness history and activity history. A case was implicated as a cause of diffuse unilateral cases is unknown. However, many human cases subacute neuroretinitis. defined as illness consistent with CLM in a staff continue to be diagnosed, and a recent national member or camper who attended the camp at survey of shelters revealed that almost 36 percent Geographic distribution any time during June 5-July 20, 2006, and had of dogs nationwide and 52 percent of dogs from symptoms during June 5-Aug. 20. All 22 persons Hookworm species are worldwide in distribution southeastern states harbored helminths capable and represent the second most common human who reported signs or symptoms met the case of causing human disease. Zoonotic hookworm definition. Although no laboratory samples were helminthic infection (after ). A.caninum infections are more geographically restricted and A. tubaeforme are widely distributed and can obtained, all 22 patients had received a clinical than other helminths, with most cutaneous diagnosis of CLM. be found in many parts of the world, mostly in larva migrans and other hookworm-associated areas with moist, warm climate. A. braziliense syndromes diagnosed in southeastern and Gulf MDCHD conducted a descriptive, cross-sectional exist in tropical and subtropical climates (southern Coast states. Persons likely to be exposed to study of the 22 cases and an environmental

Page 2 Elite health assessment of the camp property. Illness ■■ Exposure to another nearby beach in the week newly born animals at home, and provide these onset occurred during June 20-Aug. 1. The before symptom onset (nine [41 percent]). animals with early prophylactic treatment for median age of campers was 4 years (range: 2-6 ■■ Shared personal items, such as towels or intestinal parasites. Early identification of these years); and the median age of staff members clothes with other campers (four [18 percent]). high-risk animals will provide the veterinarian was 17 years (range: 16-19 years). Patients had After analyzing initial data collected during July with the opportunity to educate the owners on including erythema (100 19-25, MDCHD suspected that the sandbox the public health risks, provide them with an percent), pruritic rashes (100 percent), serpiginous was the source of infection. Staff members appropriate anthelmintic and advise them on lesions (77.3 percent), changing location of inspected the camp again on July 26 and did not how and when to administer it to their pets at rash or lesions (50.0 percent), blistering lesions find feces in the sandbox for laboratory testing. home. This approach to treatment is justified by (27.3 percent), and pus-containing lesions (18.2 Immediately after the July 26 inspection, sand in the frequency with which puppies and kittens percent). Lesions were noted on the buttocks the sandbox was removed and replaced. Two feral acquire intestinal parasites from their mothers, (68.2 percent), feet (45.5 percent), legs (27.3 cats were removed from the premises by animal and the difficulties that exist in early diagnosis. percent), hands (9.1 percent), groin (9.1 percent) control and euthanized; the cats were not tested Because young animals may continuously and abdomen (4.5 percent). Nine (40.9 percent) of for hookworm. MDCHD staff recommended acquire new infections from nursing and from the the patients had lesions in more than one location to camp administrators that the sandbox be environment, they may develop a serious illness either during a single episode or during the course covered with a tarp when not in use to prevent or even die before a prenatally or lactogenically of the infection. All but two patients used a fecal contamination and to change the sand acquired infection becomes patent and can be nonprescription topical ointment at home before regularly in accordance with American Academy diagnosed by fecal examination. seeking medical attention, and all 22 patients of Pediatrics and American Public Health While intestinal parasites are usually less of sought medical attention. MDCHD contacted Association standards. Administrators also were a problem in young adult and adult animals, every physician to confirm CLM diagnoses. advised to report stray animals to animal control they also can develop patent infections and Patients were treated with thiabendazole, for removal and to inspect the sandbox daily and contaminate the environment. Therefore, they , or . remove feces to reduce the number of potentially should be regularly monitored or treated for The mean length of time patients were at the infective larvae; larvae typically do not emerge intestinal parasite infections. While all adult camp was 3.7 weeks. Approximately 40.9 from their eggs in less than 24 hours. After the animals are at risk, those that are allowed to percent attended for two weeks, and 27.3 percent interventions were implemented on July 26, three roam or spend most of their time outside run a attended for more than six weeks. At the time additional cases were reported through Sept. 2; greater risk of becoming infected. There are a interviews were conducted (July 19-Sept. 2), however, these persons might have been exposed variety of anthelmintic drugs available that are six (27.3 percent) of the 22 patients were still before the interventions were in place. safe and effective against hookworms and other attending the camp, and 18 (81.8 percent) were intestinal helminths of dogs and cats (Table Preventive anthelmintic treatment still experiencing symptoms. All 22 patients 1 on next page). Mature animals can also be Because puppies, kittens and pregnant and participated in the half-day camp for children monitored through biannual or yearly diagnostic nursing animals are at highest risk for these aged 2-6 years. Although campers and staff stool examinations and treated with anthelmintics infections and therefore responsible for most members for both the half-day and full-day directed at specific intestinal nematodes. For of the environmental contamination and human camps were exposed to sand from the beach and animals that live in areas where heartworm disease, anthelmintic treatments are most the volleyball court, only those in the half-day () infection is enzootic, many effective when they are initiated early and camp were allowed in the playground area, which of the heartworm preventives are also effective targeted at these populations. included a sandbox containing approximately 400 against intestinal parasites (Table 1). cubic feet of sand that had been placed in the box While it has long been recognized that two years previously. Campers were in or around transplacental and transmammary infection Veterinarians can help prevent human the sandbox for approximately one hour each of hookworms could be prevented through disease day, and all campers wore bathing suits while in prophylactic treatment of pregnant dogs, no drugs Most cases of human hookworm infections this area. Fourteen (63.7 percent) of the 22 who are currently approved for this use. However, can be prevented by practicing good personal became ill did not wear shoes while sitting in the effectiveness of this approach with different hygiene, eliminating intestinal parasites from the sandbox. Four (18.2 percent) of the persons drugs approved for parasite control in dogs has pets through regular deworming and making reported seeing cats near the sandbox. been documented. potentially contaminated environments, such as MDCHD investigators arrived at the site on July If the mother did not receive prophylactic unprotected sand boxes, off limits to children. 19 to investigate the campgrounds and interview treatment, puppies and kittens must be treated It is also important to clean up pet feces on a camp administrators. Camp administrators had early and repeatedly in order to prevent patent regular basis to remove potentially infective sectioned off the sandbox already to prevent infections. In areas where hookworms are eggs before they become disseminated in the children from using the area; the camp director common, begin treating both puppies and their environment via , insects or the active had researched CLM online and identified mothers with an age-appropriate anthelmintic migration of the larvae. Hookworm eggs can contaminated sandboxes as possible sources of at 2, 4, 6 and 8 weeks of age. Some recommend develop into infective stage larvae in the soil in infection. During their initial visit to the site, extending this to 12 weeks and then treating as little as two days, depending on temperature MDCHD investigators observed cats around monthly until the pet is 6 months old. Because and humidity. the playground sandbox and noticed animal prenatal infection does not occur in kittens, Most pet owners do not know that their pets may feces inside the sandbox; no fecal samples were preventive treatment should begin at 3 weeks of carry worms capable of infecting people. Therefore, collected. Interviews with the camp director age, and be repeated at 5, 7, and 9 weeks. Nursing practicing veterinarians can provide an important revealed that general beach areas, to which all dogs and queens should be treated concurrently public service by recommending regular fecal campers in both age groups were exposed, were with their offspring because they often develop examinations, providing well-timed anthelmintic frequented by dogs; therefore, the sand in general patent infections along with their young. treatments, counseling clients on potential beach areas also was considered a possible source Because most puppies and kittens are not public health hazards and advising them on any of exposure. Additional possible sources of routinely brought to a veterinarian before 6-8 precautionary measures that may be undertaken. exposure considered included: weeks of age, they will already have patent Veterinarians are in an ideal position to provide pet ■■ Pets at home (10 patients [45 percent], with infections and be actively contaminating the owners with this service because of their access to eight dogs, one cat and one unknown). environment. For this reason, it is important the pet-owning public, their knowledge and training to reach out to clients who have pregnant or and their role in the human-animal bond. Elite Page 3 Table 1: Drugs for the treatment of hookworm infections in dogs and cats: Formulary Route/ Dosage Species Minimum Contraindications frequency age/weight Do not use if: Diethylcarbamazine Oral/daily 6.6mg/kg DEC Dog 8 weeks/1 lb Established heartworm infection, hepatitis; Uncinaria + Oxibendazole + 5.0mg/kg OX Oral/daily (3 days) 50mg/kg Dog None Ivermectin Oral/monthly 24 μg/kg Cat 6 weeks Uncinaria Ivermectin Oral/monthly 6 μg/kg IVM Established heartworm infection (unless larvae in tissue +Pyrantelpamoate +5 mg/kg PYR stage) Milbemycin oxime Oral/monthly 0.5mg/kg Dog 4 weeks/2 lb Established heartworm infection; Uncinaria Milbemycin oxime Oral/monthly 2mg/kg Cat 6 weeks/1.5 lb Milbemycin oxime Oral/monthly 0.5mg/kg MO Dog 4 weeks/2 lb Established heartworm infection (unless larvae in tissue +Lufenuron +10mg/kg LUF stage); Uncinaria SC/twice yearly 0.17mg/kg Dog 6 months Established heartworm infection (unless larvae in tissue stage); Uncinaria pamoate Oral/discretionary 5mg/kg Dog 2 weeks/ lb Pyrantel pamoate Oral/discretionary 5 mg/kg PYR Cat 1 month/1.5 lb Consult Veterinarian before use; Uncinaria; +Praziquantel +20 mg/kg PRA Pyrantel pamoate Oral/discretionary 5 mg/kg PYR Dog 3 weeks/2 lb Dog is pregnant +Praziquantel +5 mg/kg PRA +Febantel +25 mg/kg FEB Selamectin Topical/monthly 6mg/kg Cat 6 weeks Uncinaria

Educating and counseling pet owners ■■ How prophylactic treatment of pregnant and How do I get a hookworm infection? Pet owner education regarding intestinal nursing pets and their offspring can protect Hookworm eggs are not infective; they develop parasites and their effects on the health of both their pets from becoming infected, thus in soil to larvae that have the ability to penetrate their pets and family members should be included preventing them from shedding eggs into and the skin. Hookworm infection is transmitted in a well-pet exam. Pet owner education should contaminating the environment. primarily through the skin in contact with focus on prevention and include the following: ■■ The need for regular diagnostic fecal contaminated soil, walking or lying in ■■ Description of hookworms that infect dogs examinations of pups or kittens or contaminated sand. It can also be transmitted and cats, early signs of illness, and when pets prophylactic treatment of older pets. through the ingestion of larvae. are at greatest risk for infection (in utero and ■■ The need for prompt collection and disposal Hookworms have a complex life cycle that when nursing). of pet feces, especially in areas where children begins and ends in the small intestine. Adult ■■ How hookworms cause disease in humans, play, to remove eggs from the environment female worms produce thousands of eggs, especially in children whose play habits and before they can become a problem. which are excreted in stool. Hookworm eggs attraction to pets put them at increased risk. ■■ The need to keep children away from areas are not themselves infective. However, if they that may be contaminated with pet feces. reach soil (for example, when infected persons Additional information for clients defecate on the ground or when “night soil” is used to fertilize crops) and if the soil conditions Below is basic information that you can put into a are favorable (warm, moist, and shaded), the brochure to give to your clients. eggs hatch into larvae. The barely visible larvae What is hookworm? penetrate the skin (often through bare feet), are carried to the lungs, go through the respiratory Hookworm is an intestinal parasite of humans tract to the mouth, are swallowed and eventually that causes mild diarrhea and abdominal reach the small intestine. This journey takes about pain. Heavy infection with hookworm can a week. In the small intestine, the larvae develop create serious health problems for newborns, into half-inch-long worms, attach themselves to children, pregnant women and persons who the intestinal wall and suck blood. are malnourished. Hookworm infections occur mostly in tropical and subtropical climates. In Who is at risk? 2002, the estimated number of persons infected People who have direct contact with soil that with hookworm was 1.3 billion. contains human feces in areas where hookworm is Where are hookworms commonly found? common are at high risk of infection. Children – because they play in dirt and often go barefoot – are A.caninum and A. tubaeforme are widely at high risk, although the prevalence of hookworm distributed and can be found in many parts of infection in endemic countries continues to rise into the world. A. braziliense exist in tropical and young adulthood. Since transmission of hookworm subtropical climates (southern parts of the infection requires development of the larvae in soil, U.S., Central and South America). By contrast, hookworm is not spread person to person. Contact U. stenocephala is found in northern climes Anterior end of an adult of Ancylostoma caninum, a among children in institutional or child-care settings (Canada, the northern U.S. and Europe). dog parasite that has been found to produce a rare should not increase the risk of infection. human infection known as eosinophilic enteritis.

Page 4 Elite What are the symptoms of hookworm? Assoc. 1991; 199:702-7. Hookworms Itching and a rash at the site of where skin Hendrix CM, Homer SB, Kellman NJ, Harrelson G, Bruhn BF. Final Examination Questions touched soil is usually the first sign of infection. Cutaneous larva migrans and enteric hookworm infections. J. Am. Vet. Med. Assoc. 1996; 209(10):1763-76. These symptoms occur when the larvae penetrate Choose True or False for questions 1-5 then Kalkofen VP. Hookworms of dogs and cats. Vet. Clin. North the skin. While a light infection may cause no complete your test online at Am. Small Anim. Pract. 1987; 17:1341-54. www.elitecme.com. symptoms, heavy infection can cause anemia, Kazacos KR. Protecting children from helminthic . abdominal pain, diarrhea, loss of appetite and Contemp. Pediatr. 2000;17(3) (Suppl):1-24. 1. Kittens, like puppies, can become infected weight loss. Heavy, chronic infections can cause Little MD, Halsey NA, Cline BL, Katz SP. Ancylostoma larva with hookworm in utero. stunted growth and mental development. in muscle fiber of man following cutaneous larva migrans.Am. J. Trop. Med. Hyg. 1983; 32:1285-8. True False Can a hookworm infection cause any Prociv P, Croese J. Human eosinophilic enteritis caused by dog hookworm Ancylostoma caninum. Lancet 1990; 335:1299- serious health problems? 1302. Yes. The most serious results of hookworm Reinemeyer CR, Faulkner CT, Assadi-Rad AM, Burr JH, 2. The absence of eggs in feces assures the infection are the development of anemia and Patton S. Comparison of the efficacies of three heartworm absence of hookworm disease. protein and deficiency caused by blood loss. preventatives against experimentally induced infections with Anycylostoma caninum and in pups. J. Am. Vet. When children are continuously infected by many Med. Assoc. 1995; 206(11):1710-5. True False worms, the loss of iron and protein can retard Schantz PM. Zoonotic ascarids and hookworms: The role for growth and mental development, sometimes veterinarians in preventing human disease. Compendium on irreversibly. Hookworm infection can also cause continuing education for the practicing veterinarian 2002; 3. Rhabditiform larvae can penetrate the skin tiredness and difficulty breathing with exertion. 24(1) (Suppl):47-52. and cause infection. Severe disease can cause congestive . Stoye M. Biology, pathogenicity, diagnosis and control of Ancylostoma caninum. Dtsch. Tierarztl. Wochenschr. 1992; 99(8):315-21. True False What should I do if I think I have a http://www.cdc.gov/ncidod/eid/vol8no4/01-0273.htm hookworm infection? Visit your health care provider. Infection is 4. Uncinaria stenocephala are found in northern diagnosed by identifying hookworm eggs in a climates. stool sample. True False What is the treatment for hookworm? Hookworm infections are generally treated for 1-3 days with prescribed by your 5. Hookworm eggs can develop into infective health care provider. The drugs are effective and stage larvae in the soil in as little as two days. appear to have few side effects. Your health care provider may decide to repeat a stool exam after True False treatment. Iron supplements may be prescribed if you have anemia.

How can I prevent hookworm? 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.

References and suggested reading Acha PN, Szyfres B Pan American Health Organization (PAHO), Zoonoses and communicable diseases common to man and animals. Volume 3. Parasitoses. 2003. Scientific and Technical Publication No. 580, p. 249-252 and p.312-317. Bowman DD. Georgis’ parasitology for veterinarians. Seventh ed. Philadelphia: WB Saunders Company. 1999; 178-184. Samuel WM, Pybus MJ, Kocan AA. Parasitic diseases of wild mammals. Second ed. Ames: Iowa State University Press. 2001; 301-41. Beaver PC. Biology of soil-transmitted helminths: The massive infection. H. L. S. 1974; 12(2):116-25. Blagburn BL, Lindsay DS, Vaughan JL, et al. Prevalence of canine parasites based on fecal flotation.Comp. Contin. Educ. Vet. Pract. 1996; 18:483-509. Brazzell J.L. Fecal Analysis: How to maximize your diagnostic yield. Marshfield Labs,www. marshfieldlabs.org/proxy/ SV_Whats_New_FecalAnalysis Burke TM, Roberson EL. Prenatal and lactational transmission of Toxocara canis and Ancylostoma caninum: experimental infection of the bitch before pregnancy. Int. J. Parasitology 1985; 15:71-5. Dunn R.A and Greiner E.C. Managing hookworms in the landscape http:/edis.ifas.ufl.edu/ng007 Duwel D, Strasser H. Birth of helminth-free canine pups through maternal fenbendazole therapy. Dtsch. Tierarztl. Wochenschr. 1978; 85(6):239-41. 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.

Elite Page 5