HIGH MORTALITY OF MARSH DEER (BLASTOCERUS DICHOTOMUS) ASSOCIATED WITH HAEMONCHUS CONTORTUS IN WETLANDS OF NORTHEASTERN ARGENTINA

OROZCO MM, MARULL C, JIMENEZ I, GURTLER RE

Iguazú, Argentina

Congreso; 59th Annual International Conference of the Wildlife Disease Association; 2010

Iberá Natural Reserve, a wetlands macrosystem occupying 12,300 km2 in Corrientes,northeastern Argentina, is home to one of the most abundant populations of the endangeredmarsh deer (Blastocerus dichotomus) in the world. Marsh deer populations in Iberá showsignificant mortality patterns in some winter seasons. Gastrointestinal parasites are considered a main source of mortality to deer in wildlife and captivity, and it was hypothesized that gastrointestinal parasites were the putative cause of recurrent winter deaths. A serosurvey of three marsh deer (two alive and one died) was conducted in Iberá Reserve between May and August 2007, when 34 dead and 4 sick marsh deer were registered. The three sampled deers showed weakness and emaciation, faint and pallid mucous membranes, rough coat, good hydration, diarrhea and submandibular edema, a low ectoparasite burden with Amblyomma sp ticks, and poor body condition. No signs of predation were found. The parasiteHaemonchus contortus was identified in the three marsh deers at high intensities (3,000-20,000 eggs per gram in fresh feces and 20,000 in gastrointestinal contents). No serologicevidence of any other pathogen (Babesia sp., Anaplasma sp., trypanosomiasis, leptospirosis,anthrax, brucellosis, herpes virus, bovine viral diarrhea virus, toxoplasmosis, neosporosis and paratuberculosis) was detected. Ecological factors related to temperature and relativehumidity may have acted on the parasite and deer communities. The seasonal deer mortalitypattern observed in the Iberá area, where there are no known predators or hunting pressure,may be explained by the combined effects of seasonal resource limitation (given the steadyincrease in deer numbers), low temperatures, recurrent frost and/or drought events, andgastrointestinal parasites. In this context, disease may exert a significant impact on local deer populations and limit their abundance.