Quantitative characteristics of the foot-and-mouth disease carrier state under natural conditions in India

Authors: HAYER, SHIVDEEP SINGH - University Of Minnesota; RANJAN, RAJEEV - Indian Council Of Agricultural Research (ICAR); BISWAL, JITENDRA - Indian Council Of Agricultural Research (ICAR); MOHAPATRA, JAJATI - Indian Council Of Agricultural Research (ICAR); SHARMA, GAURAV - Indian Council Of Agricultural Research (ICAR); SUBRAMANIAM, SARAVANAN - Indian Council Of Agricultural Research (ICAR); STENFELDT, CAROLINA - Oak Ridge Institute For Science And Education (ORISE); PEREZ, ANDRES - University Of Minnesota; Rodriguez, Luis; PATTNAIK, BRAMHADEV - Indian Council Of Agricultural Research (ICAR); VANDERWAAL, KIMBERLY - Oak Ridge Institute For Science And Education (ORISE); Arzt, Jonathan

Submitted to: Transboundary and Emerging Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2016
Publication Date: 3/2/2017
Citation: Hayer, S., Ranjan, R., Biswal, J., Mohapatra, J.K., Sharma, G.K., Subramaniam, S., Stenfeldt, C., Perez, A., Rodriguez, L.L., Pattnaik, B., Vanderwaal, K., Arzt, J. 2017. Quantitative characteristics of the foot-and-mouth disease carrier state under natural conditions in India. Transboundary and Emerging Diseases. doi: 10.1111/tbed.12627.

Interpretive Summary: Foot and Mouth Disease virus (FMDV) is a highly contagious virus that can cause disease outbreaks in cloven-hoofed animals leading to large production losses, Alexandersen et al., 2003; Grubman and Baxt, 2004; Kitching et al., 2007. In the acute phase of infection, the disease is characterized by fever, lameness and vesicular lesions on tongue, muzzle, feet and teats, Arzt et al 2011. Additionally, a variable proportion of animals in a herd may be subclinically infected and not show any clinical signs of infection. This phenomenon is most common amongst vaccinated animals, McVicar and Sutmoller, 1976; Parthiban et al., 2015; Stenfeldt et al., 2016. In some clinically and subclinically infected ruminants, FMDV can be isolated from oropharyngeal fluids and/or tissues >28 days after infection. This condition is referred to as persistent FMDV infection and such animals are referred to as “carriers”, Arzt et al., 2011; Moonen and Schrijver, 2000; Salt, 2004. Although carrier cattle have not been convincingly demonstrated to infect other animals, their presence in a herd can have profound implications for international and domestic trade, Davies, 2002.

Technical Abstract: The goal of the current study was to characterize serological and virological parameters of the foot-and-mouth disease (FMD) carrier state at two farms in Nainital District, Uttarakhand State in northern India. Despite previous vaccination of cattle in these herds, clinical signs of FMD occurred in October 2013 within a subset of animals at the farms containing juvenile-yearling heifers and steers, Farm A, and adult dairy cattle, Farm B. Subsequent to the outbreak, FMD virus (FMDV) asymptomatic carriers were identified in both herds by seroreactivity to FMDV non-structural proteins (NSP) and detection of FMDV m,RNA in oropharyngeal fluid. Carriers’ seroreactivity and FMDV-detection status was subsequently monitored monthly for 23 months. The mean extinction time of the carrier state was 13.10 ± 0.20 months, with extinction having occurred significantly faster amongst the adult dairy cattle at Farm B compared to the younger animals at Farm A. Extinction of the carrier state corresponded to a clearance rate of 0.067 per month. Seroprevalence against FMDV non-structural proteins decreased over the course of the study period, but was found to increase transiently following vaccinations. These data provide novel insights into viral and host factors associated with the FMDV carrier state under natural conditions. The findings reported herein may be relevant to field veterinarians and governmental regulatory entities engaged in FMD response and control measures.