Vector-borne agents in marsh deer (Blastocerus dichotomus) during a wildlife mortality event in Iberá Wetlands, Argentina.

FIGINI, I; DI NUCCI, D.; ARGIBAY H; GUILLEMI EC; OROZCO MM

Nueva York

Conferencia; 53RD AAZV/EAZWV ANNUAL CONFERENCE; 2021

The recent emergence of several pathogens has highlighted the importance of wildlife disease surveillance for biodiversity conservation and global health.7 In this context, vector-borne disease drivers, including climate change, land use and land cover modifications, may contribute to higher incidence and wider geographic spread of these pathogens.3,8 In the wetlands of northeastern Argentina, extraordinary floods have occurred frequently in recent years, and have caused wildlife mortality events. During 2017, the largest mortality event in the last 20 years was registered in Iberá (Corrientes), with more than 400 recorded dead marsh deer (Blastocerus dichotomus). A total of 34 blood samples and 28 tissue samples (ear) from dead marsh deer were tested for the presence of vector-borne agents. After DNA extraction, blood samples were screened through PCR reactions targeting specific genes from Anaplasma sp./Ehrlichia sp. (16S rRNA), Babesia sp./Theileria sp. (18S rRNA) and Trypanosoma sp. (18S rRNA).1,4,6 Tissue samples were tested for the presence of Rickettsia sp. (internal transcribed spacer 23S-5S).5 For Anaplasma sp./Ehrlichia sp. positive samples, we performed an additional PCR targeting the A. marginale specific msp1β gene2 and we also sequenced the amplicons from Babesia sp./Theileria sp. positive samples. Molecular detection revealed the presence of Trypanosoma sp. in six of the 34 studied blood samples, two blood samples were positive for Anaplasma sp./Ehrlichia sp. and for the A. marginale specific PCR reaction, four samples tested positive for Babesia sp./Theileria sp. and all of them were identified as T. cervi. Results from the tissue analysis revealed that six of the 28 ear samples were positive for Rickettsia sp. The study of pathogens involved in marsh deer mortality events began in 2014. Until then, although the events were reported, the health status of this species was not studied in depth. Our first results were published in Orozco et al. 2020, and show the findings of an opportunistic sampling carried out between 2014 and 2016. The systematic surveys began in 2017, and the results are not comparable with the data collected previously. Future studies will allow us to elucidate this question. These findings contribute to the comprehensive approach to wildlife mortality events in the area and would favor the understanding of the role of animals in the emergence of vector-borne zoonotic pathogens, in pursuit of improving global and animal public health. ACKNOWLEDGMENTSThe authors would like to thank the participatory surveillance network of Corrientes (researchers, veterinarians, park rangers and the local community) for their assistance in the field, especially the technical staff off the Parks and Reserves Directorate of Corrientes and Iberá National Park. This study was supported by awards from Agencia Nacional de Promoción Científica y Tecnológica (PICT 2015-2001), The Zebra Foundation for Veterinary Zoological Education, Fresno Chaffee Zoo Wildlife Conservation Grant, and Neotropical Grassland Conservancy. LITERATURE CITED1. Bekker C, de Vos S, Taoufik A, Sparagano O, Jongejan F. Simultaneous detection of Anaplasma and Ehrlichia species in ruminants and detection of Ehrlichia ruminantium in Amblyomma variegatum ticks by reverse line blot hybridization. Vet Microbiol. 2002;89:223-238.2. Bilgiç HB, Karagenç T, Simuunza M, Shiels B, Tait A, Eren H, Weir W. Development of a multiplex PCR assay for simultaneous detection of Theileria annulata, Babesia bovis and Anaplasma marginale in cattle. Exp Parasitol. 2013;133:222-229.3. Brown L, Murray V. Examining the relationship between infectious diseases and flooding in Europe. Disaster Heal. 2013;1:117-127. 4. Gubbels JM, de Vos AP, van der Weide M, Viseras J, Schouls LM, de Vries E, Jongejan F. Simultaneous detection of bovine Theileria and Babesia species by reverse line blot hybridization. J Clin Microbiol. 1999;37:1782-1789.5. Jado I, Escudero R, Gil H, Jiménez-Alonso, MI, Sousa R, García-Pérez AL, Rodríguez-Vargas M, Lobo B, Anda P. Molecular method for identification of Rickettsia species in clinical and environmental samples. J Clin Microbiol. 2006;44:4572-4576. 6. Paoletta MS, López Arias L, de la Fournière S, Guillemi EC, Luciani C, Sarmiento NF, Mosqueda J, Farber MD, Wilkowsky SE. Epidemiology of Babesia, Anaplasma and Trypanosoma species using a new expanded reverse line blot hybridization assay. Ticks Tick Borne Dis. 2018;9:155-163. 7. Ryser-Degiorgis MP. Wildlife health investigations: needs, challenges and recommendations. BMC Vet Res. 2013;9:223. https://doi.org/10.1186/1746-6148-9-223.8. Zuckerman MK, Harper KN, Barrett R, Armelagos, GJ. The evolution of disease: anthropological perspectives on epidemiologic transitions. Glob Health Action. 2014;7:10.3402/gha.v7.23303.