Journal of Wildlife Diseases, 46(3), 2010, pp. 939–943 # Wildlife Disease Association 2010 Survey for Foot-and-mouth Disease in the Endangered Marsh Deer (Blastocerus dichotomus) from Marshlands of the Parana ´ River Basin, Brazil Joa ˜ o Pessoa Arau ´ jo, Jr., 1,4 Ma ´ rcia F. Nogueira, 2 and Jose ´ M. B. Duarte 3 1 Instituto de Biocie ˆ ncias, Universidade Estadual Paulista (UNESP), Departamento de Microbiologia e Imunologia, 18618-000, Botucatu, Sa ˜ o Paulo, Brazil; 2 Embrapa Pantanal, Caixa Postal 109, 79320-900, Corumba ´ , Mato Grosso do Sul, Brazil; 3 Faculdade de Cie ˆ ncias Agra ´ rias e Veterina ´rias, Universidade Estadual Paulista, Departamento de Zootecnia, 14884-900, Jaboticabal, Sa ˜ o Paulo, Brazil; 4 Corresponding author (email: jpessoa@ibb.unesp.br) ABSTRACT: Habitat fragmentation and diseas- es have resulted in a decline of the marsh deer (Blastocerus dichotomus) throughout its South American range. Our objectives were to determine whether marsh deer intended for translocation from a region of the Rio Parana ´ Basin had been infected previously by foot-and- mouth disease virus (FMDV) and whether they were carrying virus. We captured marsh deer from June to October 1998 and collected blood from 108 animals and esophageal-pharyngeal fluid from 53. Serum was tested for antibodies against three FMDV serotypes (O, A, and C) by liquid-phase-blocking sandwich enzyme-linked immunosorbent assay (ELISA). Esophageal- pharyngeal fluid was tested for FMDV RNA by reverse transcription polymerase chain reaction (RT-PCR) and inoculation into three successive baby hamster kidney (BHK-21) cell subcul- tures, followed by RT-PCR of cultures. We detected low log 10 titers (range 1.0–1.5) to FMDV subtype A 24 Cruzeiro in 19 of 108 sampled marsh deer, but failed to isolate FMDV or detect FMDV RNA in any samples. We conclude that marsh deer from our study site were unlikely to carry FMDV; however, as a preventive measure, the 19 animals with titers for FMDV were not sent to FMDV-free Brazilian states. Key words: Blastocerus dichotomus , ELISA, foot-and-mouth disease, marsh deer, Rio Parana ´ Basin, RT-PCR, serologic survey. Foot-and-mouth disease (FMD) is a highly contagious viral disease that causes serious economic losses where it occurs. In Brazil, serotypes O, A, and C have been reported, and the reference subtypes O 1 Campos, A 24 Cruzeiro, and C 3 Indaial are used in vaccines. All species in the order Artiodactyla are susceptible to infection with FMD virus (FMDV), but suscepti- bility and disease course vary widely among and even within species (Thomson, 1996). The significance of FMD for wild ruminants is largely related to the animals’ potential role as carriers of the virus (Thomson et al., 2003). The marsh deer (Blastocerus dichoto- mus, Illiger 1815) is the largest deer in South America (Duarte, 1997). Habitat fragmentation, as a result of agricultural activities and construction of hydroelectric power plants, has resulted in a dramatic decline of the species throughout its range (Beccaceci, 1994; Pinder and Seal, 1994; Duarte et al, 2003). In marsh deer, poaching and diseases transmitted by domestic animals have also contributed to this decline (Montassier et al., 2001; Szabo ´ et al., 2003; Torres et al., 2003). The species is considered by the International Union for Conservation of Nature (IUCN) and Brazilian Institute of Environment and Renewable Natural Resources (IBAMA) as vulnerable (IUCN, 2009). There is no information about the susceptibility of the marsh deer to FMDV. In 1998, free-living marsh deer popula- tions, among other species, were affected by the flooding of the Porto-Primavera hydroelectric dam water reservoir. As part of a research program supported by the Sa ˜o Paulo State Energy Company (CESP), marsh deer were captured to establish a captive population and to perform translo- cation experiments. Because plans called for some individuals to be translocated to a FMD-free zone with vaccination, our objectives were to determine if the cap- tured deer had been infected previously by FMDV and whether they carried virus. Marsh deer were captured around the Porto-Primavera hydroelectric dam in the 939