304 Vol. 24, No. 4 April 2002

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1 304 Vol. 24, No. 4 April 2002 CE Article #3 (1.5 contact hours) Refereed Peer Review Comments? Questions? compendium@medimedia.com Web: VetLearn.com Fax: KEY FACTS Visceral leishmaniasis is a progressive wasting disease that affects humans and dogs. Sand flies are the only known insect vectors for Leishmania. Previously considered an exotic parasite, Leishmania has been detected in foxhound kennels in 21 U.S. states and two Canadian provinces. Leishmaniasis in American Foxhounds: An Emerging Zoonosis? Virginia-Maryland Regional College of Veterinary Medicine Blacksburg, Virginia David S. Lindsay, PhD Anne M. Zajac, DVM, PhD Cornell University Stephen C. Barr, BVSc, MVS, PhD, DACVIM ABSTRACT: Leishmania species are flagellated protozoan parasites that can cause visceral, cutaneous, or mucocutaneous disease in humans and animals. Canine and human visceral leishmaniasis is found in parts of Europe, the Middle East, Africa, Asia, and the Americas. Dogs are an important reservoir for human infection. Leishmania species are transmitted by the bite of sand flies. Serologic and histologic methods are used to diagnose Leishmania infection. No available treatment consistently eliminates the organism, and dogs often relapse after treatment is stopped. Until early 2000 when Leishmania was detected in foxhounds, canine leishmaniasis was thought to be an unimportant disease in North America. Leishmaniasis has become a potential emerging zoonotic disease; therefore, veterinarians should be aware of its presence in the United States. Leishmania species are flagellated protozoan parasites in the phylum Sarcomastigophora. These parasites can cause visceral, cutaneous, or mucocutaneous disease in both humans and animals. The Leishmania donovani complex of species has caused canine and human visceral leishmaniasis in parts of Europe, the Middle East, Africa, Asia, and the Americas. 1 Dogs are an important reservoir for human infection. 2,3 The member of the L. donovani complex most often found in the Mediterranean basin is Leishmania infantum. Leishmania chagasi, a similar or identical 1 parasite, is recognized as a cause of visceral leishmaniasis in Latin America. LIFE CYCLE Leishmania species are transmitted by the bite of sand flies (Phlebotomus and Lutzomyia species). Fleas, ticks, and other arthropods are not involved in trans-

2 Compendium April 2002 Canine Leishmaniasis 305 Sand fly Promastigote Mammalian skin Figure 2 Promastigotes of the Leishmania infantum Virginia Tech-3 strain of Leishmania from culture. Ingested by the fly Infect other cells To internal organs Promastigote Amastigotes released Ingested by the macrophage Amastigotes in the macrophage Figure 1 Life cycle of Leishmania infantum. mission. The sand flies inject flagellated stages, termed promastigotes, into the skin of the host (Figure 1). Promastigotes are elongate stages that have a single nucleus, an anterior flagellum, and a kinetoplast (Figure 2). The kinetoplast is the area of the parasite from which the flagellum originates. Promastigotes are motile and can pull themselves along by their anterior flagellum. The parasites are ingested by macrophages but are not killed. Inside the macrophages, the promastigotes withdraw their external flagellum and become amastigotes. Amastigotes are round to slightly oval stages (Figure 3) and have a single nucleus, a kinetoplast, and a rudimentary flagellum. The amastigotes divide by binary fission until they rupture the host cell. The released amastigotes are ingested by other macrophages, thereby infecting new cells. The infection spreads from the skin to internal organs by movement of infected macrophages or amastigotes in the vascular system. Sand flies become infected when they ingest amastigotes while feeding on an infected host. Inside the sand fly, the amastigotes become promastigotes and multiply by binary fission in the gut of the fly. Figure 3 Amastigotes (arrows) in a lymph node biopsy from a dog. The promastigotes migrate to the hypostome of the sand fly and are inoculated when the fly feeds. The promastigotes are ingested by macrophages, and the new host is infected. Evidence indicates that transmission of Leishmania species may also occur through the exchange of blood or other body secretions. 4 Congenital transmission of L. infantum has also been reported in dogs, 5 but the importance of these alternate routes in maintaining canine Leishmania is unknown. CLINICAL SIGNS IN DOGS Clinical signs of leishmaniasis in foxhounds and other dogs are many and variable. 6 Many dogs are naturally resistant and appear clinically normal despite being infected. These dogs may show only a localized

3 306 Small Animal/Exotics Compendium April 2002 nodular reaction at the site of the sand fly bite. In endemic areas, it is believed that only 10% of infected dogs develop overt clinical disease. 6 Clinical signs include local or generalized lymphadenopathy; alopecia; cutaneous lesions; anemia; splenomegaly; epistaxis; emaciation; ocular lesions; renal failure; lameness; diarrhea; and long, deformed claws. Body temperature is usually normal or below normal. Canine leishmaniasis is a slowly progressive disease (Figure 4). It is believed that dogs that develop clinical leishmaniasis have a genetic predisposition to mount a humoral rather than a cell-mediated immune response. The cell-mediated immune response to Leishmania antigen and other antigens is decreased in dogs with leishmaniasis. 7,8 Dogs with clinical leishmaniasis have higher levels of IgG1 antibodies, Figure 4 Emaciated foxhound. Leishmania species were isolated from the dog s bone marrow and lymph nodes. Figure 5 Fluorescent micrograph of sera from a foxhound demonstrating a positive reaction to promastigotes. whereas asymptomatic dogs have higher levels of IgG2 antibodies. 9,10 DIAGNOSIS AND ANTIBODY RESPONSES The diagnosis of leishmaniasis is often difficult due to the variability of clinical presentations. The simplest method is to demonstrate amastigotes in stained smears from skin lesions, bone marrow, or aspirates from enlarged lymph nodes. Unfortunately, depending on the method used, this is effective only about 30% (lymph nodes) to 60% (bone marrow) of the time. 6 Histologic examination of biopsies can also be used but has low sensitivity. Serologic methods can be used to detect antibodies. The indirect fluorescent antibody (IFA) test is the gold standard by which other serologic tests are measured (Figure 5). Serologic examinations are conducted at initial dilutions of serum at 1:16. A cutoff titer of 1:64 is usually considered positive. However, Leishmania parasites have been isolated from foxhounds with titers of 1:16. Other serologic methods include complement fixation, indirect hemagglutination, latex agglutination, direct agglutination of amastigotes or promastigotes, counterimmunoelectrophoresis, ELISA, colloidal gold immunoassay, and Western blot. 6 The polymerase chain reaction (PCR) can be used to detect Leishmania in blood, lymph node aspirates, and bone marrow biopsies. 3,11 Although PCR is powerful, a false-negative test can result if few parasites are present. Bone marrow is the tissue of choice followed by lymph node aspirates and blood. Animal inoculation (hamsters) and in vitro culture can also be conducted and are about 80% as sensitive as PCR using bone marrow. 12 TREATMENT In countries where canine leishmaniasis is endemic, antimonials, including meglumine antimonate (Glucantime, Rhone-Merieux, Paris, France) and to a lesser extent sodium stibogluconate (Pentostam, Wellcome, Beckenham, United Kingdom), in combination with allopurinol (for maintenance) are the main drugs used in treatment. During recent years, the use of these drugs has decreased mainly because of the development of resistance, and new drugs have been shown to be efficacious, making combination long-term therapy possible with few side effects. In general, canine visceral leishmaniasis is more difficult to treat than the human form of the disease. As of yet, no one treatment regimen is completely curative in all dogs, and relapses are common once the drugs are withdrawn. Of the antimonials, only Pentostam is available in the United States; however, it must be obtained from the Centers for Disease Control and Prevention (CDC),

4 308 Small Animal/Exotics Compendium April 2002 Atlanta, Georgia. It is an aqueous solution that has a concentration of 330 mg/ml of agent, which is equivalent to 100 mg/ml pentavalent antimony. Both sodium stibogluconate and meglumine antimonate are administered on the basis of their antimony content. Antimony compounds are eliminated faster in dogs if given intramuscularly (IM) rather than subcutaneously (SC) or intravenously (IV), and it is important to maintain serum levels of the compound to treat leishmaniasis. Pentavalent antimonials are relatively well tolerated. Adverse reactions include pain at the injection site, gastrointestinal symptoms, delayed muscle pain, and joint stiffness. Canine leishmaniasis is treated with sodium stibogluconate to deliver 30 to 50 mg/kg body weight pentavalent antimony by either IV or SC administration at once-daily intervals for 3 to 4 weeks. 13 Because antimonials are rapidly excreted, other studies 14 report that higher doses (75 mg/kg body weight SC q12h) will help patients maintain higher drug levels for longer periods, thereby reducing the risk of developing resistance. Because injections are frequently painful and expensive (especially in large dogs), owners often stop treatments early, especially when the initial clinical response gives a false impression of a rapid cure. Thus the selection for drug resistance in these cases is high. Relapses may occur a few months to a year after therapy, and the patient should be treated with another round of pentavalent antimony. The use of pentavalent antimonials is contraindicated in patients with myocarditis, hepatitis, or nephritis as the drugs may exacerbate these conditions. Allopurinol, a synthetic isomer of hypoxanthine, is used extensively for its inhibitory action of xanthine oxidase, thereby decreasing the production of uric acid (by inhibiting the conversion of hypoxanthine to xanthine and xanthine to uric acid), leading to the dissolution of ammonium acid urate uroliths in dogs. Leishmania parasites hydrolyze allopurinol to an aberrant analogue of inosine that is incorporated in place of ATP into Leishmania RNA, resulting in interference with normal protein synthesis. The current regimen of choice is a combination of meglumine antimonate (75 mg/kg/day SC for 20 to 30 days and for a further 20 days if clinical signs persist) and allopurinol (15 to 30 mg/kg PO q12h for 12 or more months). 15,16 Other studies 17 have reported success with allopurinol (20 mg/kg/day PO for 1 week each month) to maintain dogs in remission after an initial induction treatment of meglumine antimonate (100 mg/kg/day SC for 20 days) followed by a 2-week rest period and a further 10-day course of meglumine antimonate as well as allopurinol (30 mg/kg/day PO for 30 days). Allopurinol alone (10 mg/kg/day PO for 2 to 24 months) is effective in producing clinical cures, but relapses are common after therapy is discontinued. In addition, the organism can still be found (either by PCR or culture) after treatment, suggesting that allopurinol alone cannot be recommended in endemic areas. 18 Because antimonials are difficult to obtain in the United States, serologically positive foxhounds are currently receiving daily allopurinol, which seems to maintain them in an asymptomatic state, and their serologic titers also drop after treatment (S. C. B.). Serologic response to Leishmania antigens (as measured by ELISA, IFA, and Western blot) decreases, and cellular immune responses to parasite antigens are reestablished after antimonial treatment Amphotericin B, a naturally occurring polyene macrolide, is mainly used in the United States for treating systemic fungal infections (e.g., blastomycosis, histoplasmosis). Soluble monomers of the drug bind to sterols (mainly ergosterol) in cell membranes, thereby altering cell permeability. Leishmania species are killed when aqueous pores permeable to small

5 Compendium April 2002 Canine Leishmaniasis 309 cations and anions are formed. Because the aqueous form of the drug is not absorbed from the gastrointestinal tract, is it usually given intravenously. Although amphotericin B reaches high drug concentration in most tissues, is it poorly absorbed into bones, brain and cerebrospinal fluid, ocular tissues, and body cavities. Various protocols for administration of amphotericin B to treat systemic fungal infections are published, but few have shown efficacy against Leishmania species. Lamothe 23 described a rapid perfusion method in which 0.5 to 0.8 mg/kg body weight is diluted in 10 to 60 ml of 5% dextrose and administered over 15 to 45 seconds every 48 hours until a total cumulative dose of 8 to 15 mg/kg has been reached. This dosage was used to obtain a good clinical recovery in 25 of 28 dogs (80%), 90% of which did not relapse after 12 months (even without maintenance therapy). Amphotericin B is nephrotoxic when given intravenously (as a result of renal vasoconstriction and a reduction in glomerular filtration rate). The nephrotoxicity is dose-dependent and can be easily reduced by monitoring renal function during therapy. Although not described for specific use in dogs with Leishmania, a practical, relatively nontoxic and inexpensive method of administering the aqueous form of the drug is by the subcutaneous route as described for the treatment of cryptococcosis in dogs. 24 In this protocol, amphotericin B is administered two to three times a week (0.5 to 0.8 mg/kg added to 500 ml of 0.45% saline/2.5% dextrose SC to a cumulative dose of 8 to 26 mg/kg), resulting in lower but more sustained blood levels and therefore lower toxicity. It is doubtful that longterm treatment removes the Leishmania parasites from the body, but clinical signs can be kept at bay for months and even years. Although not reported, a protocol using aqueous amphotericin B given subcutaneously as an induction therapy followed by oral maintenance allopurinol may be a practical and inexpensive method for treating leishmaniasis in many affected dogs. Liposome formulations of amphotericin B (five doses of 3 mg/kg to a total dose of 15 mg/kg) may be efficacious for the treatment of canine leishmaniasis. The agent has the advantage of lower nephrotoxicity but the disadvantage of a considerable increase in cost. 25 Paromomycin (aminosidine) given IM at 20 mg/kg body weight daily for 15 days will greatly improve clinical signs of visceral leishmaniasis in dogs, but parasitologic relapses often occur within 50 to 100 days. 26 Three of 12 dogs treated with higher doses (40 mg/kg daily for 30 days) maintained clinical and parasitologic cures for 4 years, but the side effect of renal insufficiency occurred in some dogs. Like most aminoglycosides, when given systemically, nephrotoxicity is the main side effect. If paromomycin is administered SC with antimony, there is no effect on the kinetics of paromomycin, but there is a marked effect on the kinetics of antimony. 27 Serum levels of antimony remain higher, and the dose should be adjusted to prevent toxic levels of the metal from appearing in the blood. Currently, paromomycin is not a practical or safe method of treating canine leishmaniasis. Other drugs used to treat canine leishmaniasis have included the azoles (ketoconazole, miconazole, fluconazole, itraconazole), which can be given orally and may be candidates for maintenance therapy. 16 However, their cost would preclude their use over allopurinol. Pentamidine isethionate is efficacious (4 mg/kg IM q48h for 15 injections minimum) but painful on administration. Although some dogs show parasitologic or clinical cures when treated with these compounds, none is 100% efficacious. ENDEMIC INFECTIONS IN FOXHOUNDS IN THE UNITED STATES Until early 2000, canine leishmaniasis was thought to be an unimportant disease in North America. Most reported cases were in dogs that had originated in or traveled to areas where leishmaniasis is endemic. 28 The first case of endemic visceral leishmaniasis was reported in a 7-year-old female foxhound from Oklahoma. 29 The dog, which had never been outside the United States and had been confined to a 150-mile radius around Oklahoma City, had generalized alopecia associated with Demodex folliculorum infestation. The dog came from a kennel of 17 foxhounds, and additional dogs in the kennel were found to be infected. 30 The second case of endemic leishmaniasis in the United States came from an English foxhound in an Ohio research colony. 31 A male dog developed visceral leishmaniasis and eventually died. Both its dam and sire were born in the United States. Serologic examination of 25 dogs from the colony revealed that eight had antibodies to Leishmania. Other isolated cases of leishmaniasis in dogs with no history of foreign travel occurred in a Basenji in Texas 32 and a toy poodle in Maryland. 33 In early 2000, the CDC was informed of the diagnosis of leishmaniasis in foxhounds from a hunt club in New York. 34 In late summer 1999, a number of foxhounds at the club had developed signs of the disease, including bleeding, wasting, seizures, hair loss, skin lesions, kidney failure, and swollen limbs and joints. Several dogs had died. Some of the affected dogs were sent to the College of Veterinary Medicine, North Carolina State University, Raleigh, for diagnostic studies. Cytopathologic examination of joint fluid from one of the hounds revealed amastigote forms of Leishmania species. This finding was confirmed at necropsy of several dogs, and promastigotes were isolated and grown

6 310 Small Animal/Exotics Compendium April 2002 in culture. Diagnostic studies at the club s kennel revealed that 39 of 93 (42%) foxhounds were seropositive for antibodies to Leishmania species. Culture of aspiration or biopsy material from lymph nodes and other tissues from 15 seropositive dogs resulted in isolation of Leishmania species promastigotes from 15 dogs. In view of the sporadic cases seen in hounds in the past 20 years in the United States, the CDC has undertaken a large-scale survey of foxhounds in this country. Since early 2000, sera from more than 10,000 foxhounds and other hunting dogs in 35 states and Canada have been tested. High antibody titers of at least 1:64 (indicative of active infection) have been found in approximately 2% of the foxhound samples, although some culture-positive dogs had lower titers. Seropositive dogs have been detected in 61 kennels in 21 states and two Canadian provinces. Organisms from numerous dogs in several states and Canada were typed at the Institute of Public Health, Rome, and were all found to belong to the L. infantum MON1 zymodeme, which is the most common type isolated from human visceral leishmaniasis cases in the Mediterranean area. Fewer pet dogs and wild canids have also been serotested but have not shown evidence of infection. 34 Confounding the issue of diagnosis is the recent finding by the CDC that serologic cross-reactions can occur between Leishmania and another protozoan parasite, Trypanosoma cruzi. Infection with T. cruzi has been reported in various wild animals and dogs in many states in the eastern United States. The CDC is now expanding its program to include a test differentiating between the two organisms. a The means by which infection is transmitted in dogs in the United States is not well understood. Sand flies are widely distributed in much of the United States, although they are usually not regarded as an important human or livestock pest. One species, Lutzomyia shannoni, is widely distributed throughout the eastern United States and can be found as far north as New Jersey. 35 Some data indicate that this species may be a competent vector of another Leishmania species, Leishmania mexicana. 35 Sand flies are small (only a few millimeters in length) and have hairy bodies and wings. Only female sand flies are blood feeders, and many species feed on a variety of hosts. Females lay their eggs in protected areas with high levels of organic material. 36 Most of the epidemiologic data collected does not support a major role for sand fly transmission in the United States. Beagles that were kenneled with affected foxhounds in New York and other foxhounds and pet a Personal communication: Dr. Peter Schantz, Atlanta, GA, July dogs kenneled within 10 miles of that hunt club were not seropositive. The close contact of individual foxhounds in packs combined with frequent movement of foxhounds around the United States may be responsible for direct transmission of the parasite between dogs. 34 The risk of canine infection to humans in the United States has not been established. Cases of human visceral leishmaniasis originating in the United States have not been reported. Sand flies are not a familiar human pest and, although direct transmission of the organism from dogs is theoretically possible, there are no cases reported in the literature. The CDC is currently testing humans who come into daily contact with infected foxhounds. 34 Even in the Mediterranean region where 20% of dogs are infected, there are few clinical cases in humans. Individuals most at risk of developing disease are those with weakened immune systems. 37 FUTURE CONSIDERATIONS The most important questions about Leishmania infections in foxhounds remain to be answered. It is unknown how the parasite is maintained in foxhounds in the United States. Likewise, it is unknown whether other dogs or humans are at risk due to the presence of infected foxhounds. Serologic studies on the prevalence of Leishmania in foxhounds and those humans associated with them are presently being conducted in many laboratories. Epidemiologic studies on potential arthropod vectors and other means of parasite transmission are also being conducted. REFERENCES 1. Mauricio IL, Howard MK, Stothard JR, Miles MA: Genomic diversity in the Leishmania donovani complex. Parasitology 119: , Ashford DA, David JR, Freire M, et al: Studies on control of visceral leishmaniasis: Impact of dog control on canine and human visceral leishmaniasis in Jacobina, Bahia, Brazil. Am J Trop Med Hyg 59:53 57, Reale S, Maxia L, Vitale F, et al: Detection of Leishmania infantum in dogs by PCR with lymph node aspirates and blood. J Clin Microbiol 37: , Nuvayri-Salti N, Fallah-Kansa H: Direct non insect-vector transmission of Leishmania parasites in mice. Int J Parasitol 15: , Mancianti F, Sozzi S: Isolation of Leishmania from a newborn puppy. Trans R Soc Trop Med Hyg 89:402, Ferrer LM: Clinical aspects of canine leishmaniasis. Proc Int Canine Leishmania Forum:6 10, De Luna R, Vuotto ML, Ielpo MT, et al: Early suppression of lymphoproliferative response in dogs with natural infection by Leishmania infantum. Vet Immunol Immunopathol 70:95 103, Moreno J, Nieto J, Chamizo C, et al: The immune response and PBMC subsets in canine visceral leishmaniasis before, and after, chemotherapy. Vet Immunol Immunopathol 71: , Deplazes P, Smith NC, Arnold P, et al: Specific IgG1 and IgG2

7 312 Small Animal/Exotics Compendium April 2002 antibody responses of dogs to Leishmania infantum and other parasites. Parasite Immunol 17: , Nieto CG, Garcia-Alonso M, Requena JM, et al: Analysis of the humoral immune response against total and recombinant antigens of Leishmania infantum: Correlation with disease progression in canine experimental leishmaniasis. Vet Immunol Immunopathol 67: , Steuber S, Moritz A, Schirrmann I, Greiner M: PCR follow-up examination after treatment of canine leishmaniosis (CaL). Tokai J Exp Clin Med 23: , Ashford DA, Bozza M, Freire M, et al: Comparison of the polymerase chain reaction and serology for the detection of canine visceral leishmaniasis. Am J Trop Med Hyg 53: , Slappendel RJ, Teske E: The effect of intravenous or subcutaneous administration of meglumine antimonate (Glucantime ) in dogs with leishmaniasis. A randomized clinical trial. Vet Q 19:10 13, Valladares JL, Riera C, Alberola JG, et al: Pharmacokinetics of meglumine antimonate after administration of a multiple dose in dogs experimentally infected with Leishmania infantum. Vet Parasitol 75:33 40, Denerolle P, Bourdoiseau G: Combination allopurinol and antimony treatment versus antimony alone and allopurinol alone in the treatment of canine leishmaniasis (96 cases). J Vet Intern Med 13: , Lamothe J: Treatment of canine leishmaniasis from A (amphotericin B) to Z (zyloric). Proc Int Canine Leishmania Forum:12 17, Ginel PJ, Lucena R, Lopez R, Molleda JM: Use of allopurinol for maintenance of remission in dogs with leishmaniasis. J Small Anim Pract 39: , Cavaliero T, Arnold P, Mathis A, et al: Clinical, serologic, and parasitologic follow-up after long-term allopurinol therapy of dogs naturally infected with Leishmania infantum. J Vet Intern Med 13: , Aisa MJ, Castillejo S, Gallego M, et al: Diagnostic potential of Western blot analysis of sera from dogs with leishmaniasis in endemic areas and significance of the pattern. Am J Trop Med Hyg 58: , Riera C, Valladares JL, Gallego M, et al: Serological and parasitological follow-up in dogs experimentally infected with Leishmania infantum and treated with meglumine antimonate. Vet Parasitol 84:33 47, Fernandez-Perez FJ, Mendez S, de la Fuente C, et al: Value of western blotting in the clinical follow-up of canine leishmaniasis. J Vet Diagn Invest 11: , Rhalem A, Sahibi H, Lasri S, Jaffe CL: Analysis of immune responses in dogs with canine visceral leishmaniasis before, and after, drug treatment. Vet Immunol Immunopathol 71:69 76, Lamothe J: A new prospect on canine leishmaniasis: Treatment with amphotericin B. Prat Med Chir Anim Comp 32: , Malik R, Graig AJ, Wigney DI, et al: Combination chemotherapy of canine and feline cryptococcosis using subcutaneously administered amphotericin B. Aust Vet J 73: , Oliva G, Gradoni L, Ciamarella P, et al: Activity of liposomal amphotericin B (AmBisome ) in dogs naturally infected with Leishmania infantum. J Antimicrob Chemother 36: , Vexenat JA, Olliaro PL, Castro JAF, et al: Clinical recovery and limited cure in canine visceral leishmaniasis treated with aminosidine (paromomycin). Am J Trop Med Hyg 58: , Belloli SC, Ceci L, Carli S, et al: Disposition of antimony and aminosidine in dogs after administration separately and together: Implications for therapy of leishmaniasis. Res Vet Sci 58: , Bravo L, Frank LA, Brenneman KA: Canine leishmaniasis in the United States. Compend Contin Educ Pract Vet 15: , Anderson DC, Buckner RG, Glenn BL, MacVean DW: Endemic canine leishmaniasis. Vet Pathol 17:94 96, Kocan KM, MacVean DW, Fox JC: Ultrastructure of Leishmania species isolated from dogs endemic in Oklahoma. J Parasitol 69: , Swenson CL, Silverman J, Stromberg PC, et al: Visceral leishmaniasis in an English foxhound from an Ohio research colony. JAVMA 193: , Sellon RK, Menard MM, Meuten D, et al: Endemic visceral leishmaniasis in a dog from Texas. J Vet Intern Med 7:16 19, Eddlestone SM: Visceral leishmaniasis in a dog from Maryland. JAVMA 217: , Schantz PM, Steurer F, Jackson J, et al: Emergence of visceral leishmaniasis in dogs in North America. Proc Int Canine Leishmaniasis Forum:4 13, Young DG, Perkins PV: Phlebotomine sand flies of North America (Diptera: Psychodidae). Mosquito News 44: , Marquardt WC, Demaree RS, Grieve RB (eds): Parasitology & Vector Biology, ed 2. New York, Harcourt/Academic Press, 2000, pp Enserink M: Infectious diseases. Has leishmaniasis become endemic in the U.S.? Science 290: , ARTICLE #3 CE TEST The article you have read qualifies for 1.5 contact hours of Continuing Education Credit from the Auburn University College of Veterinary Medicine. Choose the best answer to each of the following questions; then mark your answers on the postage-paid envelope inserted in Compendium. 1. Leishmania parasites live inside what host cells in the canine host? a. cardiac muscle cells c. macrophages b. hepatocytes d. renal tubule cells 2. Leishmania parasites are transmitted by the bite of a. fleas. c. ticks. b. sand flies. d. mosquitoes. 3. is the gold standard test for Leishmania antibodies. a. IFA c. ELISA b. Western blot d. PCR 4 Some researchers believe that some dogs are genetically predisposed to develop clinical leishmaniasis because a. not all experimentally infected dogs develop the disease. b. larger breeds are more often clinically ill. c. some dogs mount a humoral rather than a cellmediated immune response. d. some dogs mount a localized antibody response but not a systemic response.

8 Compendium April 2002 Canine Leishmaniasis The antibody isotype is most likely to be elevated in the serum of dogs with clinical leishmaniasis. a. IgG1 c. IgA b. IgG2 d. IgM 6. In the United States, what other protozoan parasite might cause serologic cross-reactions with Leishmania in dogs? a. Giardia lamblia c. Trypanosoma cruzi b. Trichomonas species d. Balantidium coli 7. The stage of Leishmania found in host cells is called a. amastigote. c. trypomastigote. b. promastigote. d. epimastigote. 8. The stage of Leishmania found in the vector is called a. amastigote. c. trypomastigote. b. promastigote. d. epimastigote. 9. L. infantum causes what form of leishmaniasis? a. cutaneous c. focal b. mucocutaneous d. visceral 10. What agent is used most often to treat clinical leishmaniasis? a. allopurinol c. aminosidine b. antimonials d. amphotericin B