Analysis of domestic animal movements in Colombia (2006–2014) and their possible influence on the bovine brucellosis spread

Abstract

Bovine brucellosis is a zoonotic disease that causes great economic losses. The disease is endemic in Colombia and animal movements from infected herds carry a risk of introduction to other herds. With the objective of analyzing the animal movements and determining their relationship with bovine brucellosis, we performed a descriptive analysis of the space-time movement of livestock in Colombia between 2006 and 2014. Multiple linear regression models (MLR) were employed to determine the relationship between brucellosis status and animal movements at the province level. The prevalence of bovine brucellosis in cattle was the dependent variable, and a total of 14 independent variables related to location, year, census, and animal movements were included. The prevalence of bovine brucellosis was significantly affected by the province (F = 3.42; P < 0.001), the year (F = 9.03; P < 0.001), and bovine (F = 5.45; P = 0.02) and equine movements (F = 3.8; P = 0.053). Fewer cattle and more horses entered provinces with high prevalence than those with low prevalence, indicating the possible relationship between the animal movements and the brucellosis infection in the country.

Brucellosis in Colombia: Current Status and Challenges in the Control of an Endemic Disease

“…This explains why most of the participants in the program are dairy cattle and double purpose farms, while participation by beef cattle systems is very limited (13). In fact, in regions were beef cattle are predominant, surveillance activities are lower than in those that hold mainly dairy cattle (63). The number of active farms in the brucellosis free program has declined significantly in recent years, from 20,932 farms in 2015 to only 15,676 farms in 2018 (52).…”

“…It is well-known that non-regulated animal trade has important implications in the dissemination of brucellosis (65). However, despite legislation, illegal animal movement occurs inside the country, although the exact numbers are unknown (63). Illicit importation of animals that do not meet entry requirements is a current concern.…”

“…Brucellosis is one of the most important zoonoses in Latin America (83), and human cases of the disease have been reported in Colombia over the years (11). Despite its known high prevalence in animals (63), in 2015, only 656 serum samples from suspected human cases were tested. An alarming seropositivity rate of 3.8% was discovered (36).…”

“…Despite the countermeasures adopted by local authorities 20 years ago, brucellosis is still prevalent (63), and the control of the disease represents a challenge for veterinarians and public health authorities. The difficult diagnosis based on clinical signs (2) and the lack of indemnities for test-and-slaughter (13) make brucellosis an underreported disease in livestock.…”

“…According to official data, vaccination coverage has been increasing and, currently, ~98% of bovine and bubaline female populations are immunized (93). Despite this apparent high coverage, brucellosis prevalence has not had a significant decline (63), a situation that may be linked to the persistence of infected animals on farms, vaccination failure and/or the unfamiliarity of the real prevalence due to the fluctuation in the number of animals tested per year and possible errors in the interpretation of diagnostic tests. The illegal movement of animals is also relevant in the maintenance of brucellosis (94) since these animals do not meet the health requirements (including vaccination, which means that the coverage could be overestimated), representing a constant threat of introducing the disease (95).…”