Browsing by Author "Sutar A"

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    Detection of Foot-and-Mouth Disease Virus in the Absence of Clinical Disease in Cattle and Buffalo in South East Asia
    (Frontiers Media S.A., 2021-07-23) Buckle K; Bueno R; McFadden A; van Andel M; Spence R; Hamill C; Roe W; Vallee E; Castillo-Alcala F; Abila R; Verin B; Purevsuren B; Sutar A; Win HH; Thiha M; Lwin KO; Khounsy S; Phonthasy S; Souriya V; Keokhamphet C; Arzt J; Ludi A; Mioulet V; Capozzo AV
    Foot-and-mouth disease virus (FMDV) is widespread throughout much of the world, including parts of South East Asia. Surveillance is often limited in endemic areas, relying predominantly on passive outbreak reporting. As part of the World Organisation for Animal Health (OIE)'s South East Asia and China Foot-and-Mouth Disease Project (SEACFMD), field sampling was performed to help understand evidence of widespread virus exposure observed in previous studies. Serum and dry mucosal swabs were collected to evaluate the presence of FMDV RNA on the nasal, oral, and dorsal nasopharyngeal mucosal surfaces of 262 healthy cattle (n = 84 in Laos; n = 125 in Myanmar) and buffalo (n = 48 in Laos; n = 5 in Myanmar) immediately following slaughter in three slaughterhouses. Swabs and serum were tested by the OIE/FAO World Reference Laboratory for foot-and-mouth disease (WRLFMD) using pan-serotypic real-time reverse transcription-PCR (rRT-PCR) and serum was evaluated using the FMD PrioCHECK non-structural protein (NSP) ELISA. In total, 7.3% of animals had detectable FMDV RNA in one or more of the three sites including 5.3% of nasopharyngeal swabs, 2.3% of oral swabs, and 1.5% of nasal swabs. No FMDV RNA was detected in serum. Overall, 37.8% of animals were positive for NSP antibodies, indicating likely past natural exposure to FMDV. Results were comparable for Laos and Myanmar, and for both cattle and buffalo, and were not significantly different between age groups. Detectable FMDV RNA present on the oral and nasal mucosa of clinically-healthy large ruminants in Laos and Myanmar demonstrates the importance of sampling asymptomatic animals as part of surveillance, and may indicate that subclinical infection plays a role in the epidemiology of FMD in these countries.
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    Probability of freedom from foot-and-mouth disease virus serotype Asia 1 in Southeast Asia, China and Mongolia
    (Elsevier B V, 2025-11-01) Wada M; Han J-H; Purevsuren B; Rinzin K; Sutar A; Abila R; Subharat S
    Foot-and-mouth disease virus (FMDV) serotype Asia 1 has not been reported in Southeast Asia, China and Mongolia between 2018 and 2024, despite the endemicity of FMD in this region and the continued circulation of serotype Asia 1 in South Asia. While vaccines against Asia 1 are still occasionally used in this region, it is unknown whether the absence of reports indicates true disease freedom or surveillance gaps. This study aimed to estimate the sensitivity of existing passive surveillance systems, and the probability of regional freedom from serotype Asia 1 across eight countries using the scenario tree approach. Two stochastic scenario tree models were developed to estimate surveillance sensitivity for FMD (any serotypes) and serotype Asia 1 specifically. Country-specific input parameters were derived from a questionnaire survey of in-country experts on FMD vaccination practices, smallholders’ behaviour, sampling protocols and diagnostic laboratory capacity. Additionally, 2010 – 2022 data on FMD clinical samples submitted and confirmed Asia 1 cases were obtained from the World Reference Laboratory for FMD. Under a design annual incidence rate of 10 % at the village level and 20 % at the animal level, estimated surveillance sensitivity for FMD ranged from 100.0 % in Mongolia and 95.9 % in China to 1.7 % in Cambodia and < 0.1 % in Myanmar. Using the effective design incidence rate with a median of 0.02 – 0.07 % at the village level and 20 % at the animal level, the probability of detecting Asia 1 was estimated to be 0.0 – 6.7 % per country and 14.5 % for the region. The estimated probability of regional freedom from Asia 1 was 53.9 % after the first year without reporting. Over years of no reporting, this probability would increase, only if an annual risk of introduction remained below 6 %. The results were most sensitive to parameters related to sampling intensity and smallholders’ behaviour, particularly in countries with high surveillance sensitivity, such as Mongolia and China. Our findings highlight the low sensitivity of passive surveillance in the region, suggesting that serotype Asia 1 may have remained undetected under the current surveillance efforts. Strengthening data collection and continued efforts in increasing surveillance intensity are essential to improving confidence in the regional freedom from serotype Asia 1.