Identification of rotavirus and concurrent enteropathogens in foals from Mexico

Equine rotavirus is the second leading cause of diarrhoea in foals under six months of age worldwide. This viral agent causes clinical alterations and lesions that compromise the immune system, facilitating colonisation by secondary bacterial enteropathogens. These agents are associated with deformities, digestive syndromes, endotoxemia, sepsis and, in severe cases, death, resulting in significant economic losses and limiting population growth in the equine industry. Despite its clinical relevance, there are few reports on the presence of concomitant pathogens in cases of diarrhoea associated with equine rotavirus, as well as on the clinical presentation when two or more enteropathogens coexist in the same animal.

The objective of this study was to identify the presence of rotavirus and concurrent bacterial enteropathogens, describe and compare the clinical signs associated with each individual agent and in co-infection, and evaluate bacterial resistance profiles. To this end, samples were collected from sick, deceased, and healthy foals on ranches in central Mexico. A detailed medical history was taken for each specimen to gather clinical and background information, and molecular, bacteriological, parasitological, and pathological diagnostic tools were used to confirm the presence of aetiological agents.

A total of 33 samples were analysed, of which 11 tested positive for rotavirus. In each of these cases, at least three different bacterial species were isolated concomitantly, all with profiles of multi-resistance to antibiotics commonly used in equine practice.

In conclusion, the use of complementary tests revealed the circulation of pathogens that are rarely reported or have no previous records, whose impact transcends animal health by generating economic losses in the productive stage of the equine sector and representing a potential risk to public health due to their zoonotic capacity. These findings highlight the need to strengthen preventive medicine, especially vaccination, and to apply more specific and effective treatments against co-infections.