The Epidemiological Characteristics of the 2007 Foot-and-Mouth Disease Epidemic in Sarpang and Zhemgang Districts of Bhutan

Abstract

This study was undertaken to compare the epidemiological characteristics of the 2007 foot-and-mouth disease outbreak in two districts of Sarpang and Zhemgang in Bhutan. Zhemgang district recorded a significantly higher cumulative incidence in all species (26.9%) as well as for cattle (29.3%) compared to Sarpang (6.5% and 7.4%, respectively). The case fatality for cattle in Zhemgang (14.1%) was significantly higher than in Sarpang (3.3%). A total of 404 cattle and 73 pigs died of FMD in Zhemgang, whereas only 21 cattle died in Sarpang. Although all four species were affected in Sarpang, no sheep or goats were affected in Zhemgang. Spatiotemporal analyses showed the existence of four significant clusters, a primary one in Sarpang and three secondary clusters in Zhemgang. The virus belonged to the PanAsia strain of the Middle-East South-Asia topotype (O serotype), and the strain was closely related to the PanAsia strain that circulated in Bhutan during the 2003/2004 outbreaks. The severity of FMD infection in Zhemgang district could be attributed to low vaccination coverage (36.5% in 2006 when compared to 87.6% in Sarpang), inadequate biosecurity, poor nursing care of the sick animals and delayed reporting to the livestock centre. This study highlights the ability of the PanAsia strain of the O serotype to cause unprecedented morbidity and mortality, especially in a naïve population. The study also highlights the benefits of maintaining good herd immunity in the susceptible population, through adequate vaccination coverage, to minimize the severity of infection and limit the spread of disease from infected to non-infected herds.

Outbreak investigation of foot and mouth disease in Nangarhar province of war-torn Afghanistan, 2014

“…Osmani, et al 12 also reported that there is high probability of spread of FMD in the region through the continued movement of refugees across the border between Afghanistan and Pakistan and significant legal and illegal movement of animals especially at the religious occasion such as Eid-ul-Adha. Animal movements have been recognized as one of the most common method of transmission of FMD 1 , 37 , 39 , 40 . As Nangarhar province share border with Pakistan, seasonal migrations of nomadic populations through transhumance routes between Pakistan and Afghanistan along with their livestock also poses risk of trans-boundary diseases.…”

“…Small ruminants play a crucial role in the epidemiology of FMD transmission as they often show inapparent infection in these hosts and are largely ignored during national vaccination programs 39 , 45 , 46 . Furthermore, these species have ability to become carriers and can act as reservoir for further infection and spread of disease, hence trade of live sheep and goats present a major risk of entry of FMD to disease-free countries 47 .…”

“…In veterinary medicine, plenty of published information is available about FMD outbreak investigation 35 , 39 , 54 – 56 . For current study, outbreak investigation was conducted following ten steps of outbreak investigation 57 .…”