Occurrence of Neospora caninum Antibodies in Capybaras (Hydrochaeris hydrochaeris) From São Paulo State, Brazil

J. Parasitol., 94(3), 2008, p. 766 䉷 American Society of Parasitologists 2008

Occurrence of Neospora caninum Antibodies in Capybaras (Hydrochaeris hydrochaeris) From Sa˜o Paulo State, Brazil L. E. O. Yai, A. M. A. Ragozo*, W. A. Can˜o´n-Franco†, J. P. Dubey‡, and S. M. Gennari*, Centro de Controle de Zoonoses, Sa˜o Paulo, SP, Brazil; *Departamento de Medicina Veterina´ria Preventiva e Sau´de Animal, Faculdade de Medicina Veterina´ria e Zootecnia, Universidade de Sa˜o Paulo, Av. Prof. Orlando Marques de Paiva, 87, Cidade Universita´ria, CEP 05508-270, Sa˜o Paulo, SP, Brazil; †Universidad de Calidas – Manizales, Colombia Faculdad de Ciencias Agropecuarias, Calle 665 No. 26-10, Colombia; ‡Animal Parasitic Diseases Laboratory, Animal and Natural Resources Institute, Beltsville Agricultural Research Center, United States Department of Agriculture, Beltsville, Maryland 207052350. e-mail: jitender.dubey@ ars.usda.gov ABSTRACT:

Capybara (Hydrochaeris hydrochaeris) is a large rodent distributed throughout tropical America. Antibodies to Neospora caninum in 213 feral capybaras from 11 counties of the State of Sa˜o Paulo, Brazil, were assessed using the indirect immunofluorescent antibody test (titer ⱖ1:25) and found in 20 (9.4%), with titers of 1:25 in 4, 1:50 in 7, and 1:100 in 9 animals. This is the first report of occurrence of N. caninum antibodies in capybaras.

after standardization as previously reported (Can˜o´n-Franco et al., 2003). Positive and negative sera were obtained by screening the sera using IFAT at the dilution of 1:16, 1:32, and 1:64. A serum titer of ⱖ64 was considered positive and a titer of ⱕ16 as negative. Positive and negative controls were added to each slide. Antibodies to N. caninum were detected in 20 (9.4%) of 213 capybaras, with titers of 1:25 in 4 (1.9%), 1:50 in 7 (3.3%), and 1:100 in 9 (4.2%). Seropositive capybaras were detected in 7 of the 11 counties, with an occurrence that ranged from 0.0% in Andradina, Paulı´nia, Sa˜o Joa˜o da Boa Vista, and Valparaı´so, to 30.8% in Ribeira˜o Preto (Table I). Results of the present study suggest that infected capybaras may be a source of N. caninum infection for wild canids in Brazil (Can˜o´nFranco et al., 2003). Seroprevalence for N. caninum was much lower (9.4%) compared with 69% seropositivity for T. gondii in capybaras from the same state (Can˜o´n-Franco et al., 2003), indicating specificity of the tests used. This is the first report of the presence of antibodies to N. caninum in capybaras. The authors thank FAPESP for the fellowship to A. M. A. Ragozo and CNPq for the fellowship to S. M. Gennari. We also thank Zoonosis Control Center, Prefeitura do Municı´pio de Sa˜o Paulo, for providing capybara conjugate.

Neospora caninum is one of the most important causes of abortion in dairy cattle worldwide (Dubey, 2003). Cattle become infected transplacentally or by the ingestion of oocysts that have been shed by dogs and coyotes (McAllister et al., 1998; Gondim et al., 2004). Although antibodies to N. caninum have been reported in a variety of domestic and wild animals, infected animals that serve as sources of N. caninum infection for dogs and coyotes are unknown (Dubey et al., 2007). Rodents and other small mammals are considered as a potential source of N. caninum infection for dogs and coyotes. Neospora caninum antibodies have been reported in rats (Rattus spp.) and house mice (Mus musculus) from Grenada, West Indies, and the United States (Jenkins et al., 2007). Neospora caninum DNA was found in tissues of rats and/ or mice from Italy (Ferroglio et al., 2007), the United Kingdom (Hughes et al., 2006), Taiwan (Huang et al., 2004), and Grenada, West Indies (Jenkins et al., 2007). Capybara (Hydrochaeris hydrochaeris) is a large herbivorous rodent distributed widely in tropical America, and its meat is consumed by humans in many countries. We previously reported seroprevalence of antibodies to Toxoplasma gondii in 149 capybaras from Brazil (Can˜o´nFranco et al., 2003). The objective of the present paper is to report seroprevalence of N. caninum in capybaras, the first time from this host. In total, sera of 213 capybaras from 11 counties were tested (Table I). Of these, 149 sera were those previously tested for T. gondii antibodies, and 64 were additional animals. Blood samples were collected from jugular or brachial veins, stored for 6 to 8 hr at approximately 4 C, and centrifuged; sera were stored at ⫺20 C. The indirect immunofluorescent antibody test (IFAT) was used to detect antibodies to N. caninum with a cutoff value of 1:25 (Camargo, 1974; Dubey et al., 1988). The positive sera were serially diluted 2-fold up to the maximum titer for the reaction. Anti-capybara conjugate prepared in sheep and labeled with fluorescein isothiocyanate was used in a 1:200 dilution

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TABLE I. Seroprevalence against N. caninum (IFAT ⱖ 25) in capybaras from different counties in Sa˜o Paulo State, Brazil. Samples County

Examined

Positive

%

Andradina Campinas Cordeiro´polis Cosmorama Monte Alegre do Sul Paulı´nia Pirassununga Ribeira˜o Preto Sa˜o Joa˜o da Boa Vista Sa˜o Paulo Valparaı´so Total

10 61 9 15 32 68 17 13 1 40 7 213

0 7 2 1 1 0 1 4 0 4 0 20

0.0 11.5 22.2 6.7 3.1 0.0 5.9 30.8 0.0 10.0 0.0 9.4 766