|RANJAN, RAJEEV - Indian Council Of Agricultural Research-Directorate Of Foot And Mouth Disease|
|BISWAL, JITENDRA - Indian Council Of Agricultural Research-Directorate Of Foot And Mouth Disease|
|SUBRAMANIAM, SARAVANAN - Indian Council Of Agricultural Research-Directorate Of Foot And Mouth Disease|
|DASH, BANA - Indian Council Of Agricultural Research-Directorate Of Foot And Mouth Disease|
|SINGH, KARAM - Indian Veterinary Research Institute|
|PATTNAIK, BRAMHADEV - Indian Council Of Agricultural Research-Directorate Of Foot And Mouth Disease|
Submitted to: Tropical Animal Health and Production
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/17/2018
Publication Date: 2/1/2018
Citation: Ranjan, R., Biswal, J.K., Subramaniam, S., Dash, B.B., Singh, K.P., Arzt, J., Rodriguez, L.L., Pattnaik, B. 2018. Evidence of subclinical foot-and-mouth disease virus infection in young calves born from clinically recovered cow under natural condition. Tropical Animal Health and Production. https://doi.org/10.1007/s11250-018-1518-6.
Interpretive Summary: Foot-and-mouth disease (FMD) is widely regarded as the most important constraint to international trade in livestock and animal-derived products. When outbreaks of FMD occur in disease free regions, like the USA and United Kingdom, the disease is typically stamped out by depopulating large quantities of cattle, pigs, and other susceptible species. One of the main reasons that the disease is controlled in this manner is because of fear of long term carriers of the disease that continue to shed virus long after the obvious signs of the disease have resolved. This syndrome has been thoroughly described to occur in adult cattle, but has not been well characterized in calves. The current, small-scale study provides a unique view into the potential role that young calves may play in the ecology of the disease. Naturally occurring cases were examined in India where the disease is common. The findings indicate that calves may be infected similarly to adult cows, and that they may be carriers. Interestingly, none of the calves that were examined ever had any signs of disease. This information would be important to managing an outbreak of FMD in the USA.
Technical Abstract: Foot-and-mouth disease (FMD) is a highly contagious and economically important, transboundary viral disease of cloven-hoofed animals. It is known that a chronic, asymptomatic FMD syndrome may occur subsequent to acute FMD in adult ruminants. However, neither asymptomatic nor persistent infection has been described in young calves. In the current investigation, FMDV infection parameters were examined for calves born to FMD-clinically recovered cows (CRC), asymptomatic cows from infected herds (ASC), and cows from herds with no history of FMD (NHF). All findings occurred under natural conditions in FMD-endemic settings in India. No calves described herein had any clinical signs of FMD. Seven out of twelve calves born to CRC cows had serological and/or virological characteristics consistent with asymptomatic FMDV infection. Three of the seven calves had seroreactivity against FMDV non-structural proteins and six of the seven calves had detectable FMDV RNA in orophayngeal fluid. Only one calf had detectable FMDV RNA at 2 consecutive samplings, 2 months apart. Infectious FMDV was not isolated from any calf in the study. None of the calves in the ASC or NHF groups had any evidence of FMDV infection. Overall, these data are consistent with calves having been either infected in utero or having been infected at a young age by post-natal exposure.