ROOPAK GOSWAMI
Shillong, Sept 10: African swine fever (ASF) may not be the only viral threat facing Meghalaya’s pig sector. A new study has found evidence of low-level, persistent circulation of porcine reproductive and respiratory syndrome (PRRS) among pigs in the state, raising concerns over the potential for future outbreaks.
The study, published in Veterinary World, was conducted by researchers from the ICAR Research Complex for North Eastern Hill Region, Umiam, and the ICAR-National Institute of Veterinary Epidemiology and Disease Informatics (ICAR-NIVEDI), Bengaluru.
The researchers tested 413 blood samples collected from apparently healthy pigs at an organised slaughterhouse in Shillong between August 2023 and July 2024. The animals originated from Ri-Bhoi, East Khasi Hills, Eastern West Khasi Hills and West Jaintia Hills districts.
Of the 413 samples, 21 tested positive for antibodies against PRRS virus, giving an apparent seroprevalence of 5.08%, while the estimated true prevalence was 3.94%. East Khasi Hills recorded the highest seroprevalence at 8.85%.
The finding is significant because the sampled pigs were apparently healthy, indicating that PRRS may be circulating silently in the pig population without producing obvious clinical signs.
PRRS can cause reproductive failure in sows and respiratory disease in pigs, with young animals particularly vulnerable to severe illness and mortality. The researchers noted that Meghalaya’s predominantly smallholder and backyard pig-rearing systems, combined with limited biosecurity, could increase the risk of the disease spreading and causing larger outbreaks.
A similar transboundary disease like ASF, PRRS entered India through the Northeast around 2013 and has since become endemic in Meghalaya, as evidenced by the low-level circulation of PRRS antibodies in the pig population.
The researchers also highlighted the detection of both PRRS and ASF in pigs in neighbouring Assam, warning that co-infections could further complicate disease control and increase the impact on pig health and the livelihoods of communities dependent on pig farming.
The PRRS prevalence recorded in the latest study was also higher than figures reported from Meghalaya in earlier studies, which recorded prevalence of 2.8% in 2014, 2.7% in 2015 and 3.62% in 2016.
However, the researchers cautioned that the findings do not establish an active PRRS outbreak. The study relied on slaughterhouse samples and detected antibodies, which indicate previous exposure but do not by themselves confirm active infection. The study also did not cover imported pigs or assess informal pig-trade routes and cross-border animal movements.
The authors recommended regular surveillance, stronger farm-level biosecurity, improved pig traceability and closer monitoring of animal movement, along with coordinated measures to control both PRRS and ASF.
The authors said ICAR-NIHSAD is actively working on a PRRS vaccine, which is expected in the near future.
