Babesia sp. and Anaplasma marginale Co-infection Appraisal in Cattle

RUYBAL P; PEREZ A; GUILLEMI E; ZIMMER P; NEUMANN R; ECHAIDE I; PETRIGH R; FARBER M

Lubeck

Conferencia; 10th Biennial Conference - STVM-2009; 2009

STVM

Babesia sp. and Anaplasma marginale Co-infection Appraisal in Cattle.   Ruybal P1, Perez A2, Guillemi E1, Zimmer P3, Neumann R4, Echaide I5, Petrigh R1, Farber M1. 1.  Instituto de Biotecnología, Centro de Investigaciones de Ciencias Veterinarias y Agronómicas, Instituto Nacional de Tecnología Agropecuaria (INTA), Castelar, Buenos Aires, Argentina. 2.  Center for Animal Diseases Modeling and Surveillance, Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California. 3.  INTA, EEA Mercedes, Corrientes, Argentina. 4.  INTA, EEA Cerrillos, Salta, Argentina. 5.  INTA, EEA Rafaela, Santa Fe, Argentina.   In northern Argentina, where climatic conditions support tick development, bovine babesiosis and anaplasmosis are considered an important economic constrain to livestock production. The aim of this study was to analyze Babesia sp. and Anaplasma marginale co-infection within Argentine cattle. During 2005 to 2007, 348 blood samples were collected from 12 herds (182 samples) in the northeastern (NEA), and from 10 herds (166 samples) in the northwestern (NWA) regions of the country. Specific detection of B. bovis, B. bigemina. and A. marginale was carried out by Reverse Line Blot Hybridization. Two hundred and forty six samples (70.69%) were positive to A. marginale, whereas 203 (58.33%) were positive to Babesia sp. The proportion of cattle co-infected by both agents (47.7%) was significantly higher (P<0.001) than the proportion of animals positive to either Babesia sp. (10.6%) or A. marginale (23.0%). Association between status of co-infection (Babesia-positive, Anaplasma-negative; Babesia-negative, Anaplasma-positive; Babesia-positive, Anaplasma-positive) and factors hypothesized to influence the risk of co-infection was explored for the 283 cattle that were positive to either or both agents. Association was explored using a multinomial multivariate regression model while accounting for the dependence associated to herd of origin. Factors supposed to influence the risk of co-infection were region of origin (NEA, NWA) and age of cattle (<12 months, >12 months). Cattle from NEA were at 10.2 (CI95%=4.02-25.97) and 2.2 (CI95%=1.2-4.1) higher risk of being infected by, respectively, Babesia sp. and A. marginale alone, compared with the baseline risk of being co-infected by both agents and located in NOA. After accounting for the effect related to region of origin, the risk of being infected with A. marginale alone was 5.6 higher for >12 months animals compared to the baseline risk of being co-infected by both agents and <12 months old. These results showed that co-infection status is significantly frequent (P<0.001) among cattle in which A. marginale and Babesia sp. are prevalent, ruling out infection-exclusion phenomena. Furthermore, the probability of co-infection is likely affected by environmental, biological and demographic factors such as region of origin and biological dynamics of infection.