Prevalence of Mycobacterium avium Subsp. paratuberculosis in Feral Pigeons (Columba livia) Associated with Difficulties Controlling Paratuberculosis in a Bovine Herd (Fighting Bull Breed)

Abstract

A bovine herd with a high prevalence of paratuberculosis (PTB) cohabiting with a population of pigeons was studied (2011−2020). After finding the disease in 2011, annual monitoring was performed in 2012−2014 by obtaining blood samples for ELISA and intradermal tuberculinization (IT) tests for Mycobacterium avium subsp. paratuberculosis (MAP). Positive animals were eliminated. PTB prevalence dropped from 10% to 0% but returned to similar values (9.5%) after 6 years without tests. In all animals, Ac values according to the optical density (OD) determined by ELISA increased each year and could be used to isolate herds close to the cutoff point to improve PTB control. Possible reservoirs were considered after evaluating the little success of the PTB control program, and the population of feral pigeons was studied. Specifically, 10% of the pigeon population (n = 13) was necropsied. Samples of intestine, feces, and foot skin for PCR study for MAP and samples of terminal intestine for histopathological analysis were taken. Eleven pigeons were PCR-positive against MAP, in the intestine (10/11), foot skin (3/11), and feces (1/11). The presence of MAP in pigeon feet could demonstrate its role as a mechanical disseminator of PTB, while the presence in pigeon intestine and feces could also suggest its role as a reservoir.

Keywords: Mycobacterium avium subsp. avium; cattle; fighting bull; paratuberculosis; pigeon.

Figure 1

Fighting bulls sharing habitat with pigeons. Pigeons step and peck in the stool areas of the bulls and perch on the feeders.

Figure 2

Optical density values with ELISA test in PTB-positive animals (n = 46) and their evolution during the studied period. The dashed line indicates the cutoff point established by the ELISA technique (0.36). The animals were considered positive when their serological indices were higher than the cutoff point. The animals whose serological indices were below the cutoff point were monitored in subsequent checkups and were eliminated once they were positive. After the free status of PTB reached in 2014, the serological control from 2015 to 2019 was not performed until the reappearance of the disease in 2020.