Rotavirus in pigs: when diarrhea is only the visible part of the problem

Rotavirus is one of the most relevant enteric agents in pig production, particularly in neonatal piglets and recently weaned animals. It continues to pose a challenge due to its wide distribution, high capacity for dissemination, and persistence in the environment.

Not all rotaviruses are the same

Different species of rotavirus can be detected in pigs, with rotaviruses A, B, C, and H being of particular importance. Historically, rotavirus A was considered the most relevant, but recent studies have demonstrated the importance of rotavirus C in cases of neonatal diarrhea. Different species and genotypes can circulate on the same farm, influencing infection dynamics, altering the immune response, and limiting the effectiveness of some preventive strategies. In practice, it is not enough to know that rotavirus is present: it is important to identify which types are involved in the problem.

Transmission and the moment of greatest vulnerability

Transmission occurs mainly by the fecal-oral route. Infected animals shed large quantities of viral particles in their feces, contaminating facilities, equipment, floors, drinkers, boots, clothing, and other fomites. Because the virus is resistant in the environment, infection pressure can remain high even after the animals have left, which is especially critical in farrowing and nursery rooms.

The age of the piglet is decisive in the severity of the infection. Factors that increase risk include: failures in colostrum intake, low sow immunity, large litters, mixing of piglets, inadequate environmental conditions, and high infection pressure.

The presence of co-infections with enterotoxigenic Escherichia coli and Clostridium perfringens type A worsens the scenario, intensifying diarrhea, dehydration, and mortality. In these cases, rotavirus is part of an enteric complex in which environment, immunity, management, and other pathogens determine the severity of the problem.

Pathogenesis, clinical signs, and productive impact

Rotavirus replicates in the epithelial cells of the villi of the jejunum and ileum, causing villous atrophy and crypt hyperplasia that reduce intestinal absorption capacity. Secretory mechanisms also contribute to the clinical picture. Signs include watery or pasty diarrhea, yellowish or grayish feces, apathy, anorexia, vomiting, dehydration, and rapid weight loss. Gross lesions are nonspecific: a dilated intestine with watery content, a thin intestinal wall, and a distended stomach with undigested milk.

The productive impact goes beyond mortality; lighter piglets at weaning, greater unevenness, an increase in stunted animals, poorer performance in subsequent phases, and a greater need for individual management are losses that appear indirectly. Enteric outbreaks increase labor demand, raise support costs, and can encourage the use of antimicrobials when bacterial co-infections are present. For this reason, rotavirus should be interpreted not only as a health problem, but also as a factor in the loss of production efficiency.

Control: immunity begins before birth

Since eliminating rotavirus from farms is not a practical goal, the objective must be to reduce infection pressure and minimize clinical and productive impacts. To this end, it is essential to act in an integrated way on four areas:

• Maternal immunity and colostrum intake: Sows with a good immune response transfer antibodies to piglets through colostrum and milk, protecting them during the first weeks of life. Sow management, colostrum quality, and the immunological condition of the breeding herd play a central role. Ensuring that each piglet accesses colostrum in a timely and sufficient manner is one of the highest-impact prevention measures.
• Diagnosis-guided vaccination: Vaccination is a strategic tool to reinforce maternal immunity and promote the transfer of antibodies to piglets. Molecular diagnosis is key to identifying the agents and genotypes circulating on each farm, thereby guiding the vaccination decision toward the most relevant protection for each production system. Vaccination does not replace management or biosecurity: it must be integrated into a broader control program.
• Biosecurity and environmental control: Since the virus is highly resistant in the environment, rigorous cleaning, disinfection, drying of facilities, and sanitary downtime are essential measures to reduce infection pressure, especially in farrowing and nursery rooms. When any of these steps fails, the environment can become a constant source of challenge for the piglets.
• Supportive treatment: Treatment of affected animals is mainly supportive: maintaining adequate temperature, ensuring hydration, and correcting dehydration. In cases of bacterial co-infections, antimicrobial therapy may be necessary, always under veterinary guidance.

Porcine rotavirus remains relevant due to its high dissemination, environmental resistance, and capacity to generate silent losses. Its prevention depends less on an isolated action and more on the consistency of the system.