Investigation of Melioidosis Outbreak in Pig Farms in Southern Thailand.

Wiyada Kwanhian,Jedsada Kaewrakmuk,Jirarat Songsri,Aleeza T Kessler,Kawinsaya Pukanha,Pacharapong Khrongsee,Bryn E Tolchinsky,Jitbanjong Tangpong,Apichai Tuanyok,Treenate Jiranantasak,Sarah Parker,Somporn Sretrirutchai,Suebtrakool Wisessombat,Vincentius A Testamenti

doi:10.3390/vetsci7010009

Wiyada Kwanhian, Jedsada Kaewrakmuk + Show 12 more

Open Access

https://doi.org/10.3390/vetsci7010009

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Abstract

Melioidosis, caused by the Gram-negative bacterium Burkholderia pseudomallei, is a potentially life-threatening infection that can affect humans and a wide variety of animals in the tropics. In December 2017, a swine melioidosis case was discovered during a meat inspection at a privately-owned slaughterhouse in Nakhon Si Thammarat Province in southern Thailand. The infection, which continued for several months, caused a dispute about where the disease began. An environmental investigation into two farms—both involved in raising the first infected pig—ensued. Through genetic analysis, the investigation revealed that a contaminated water supply at one farm was the probable source of infection. The three local sequence types identified in the investigation were types 51, 298 and 392.

Highlights

Melioidosis, caused by the Gram-negative bacterium Burkholderia pseudomallei, is a potentially life-threatening infection that can affect humans and a wide variety of animals in the tropics
We found that all water samples from Farm B grew many bacterial colonies (Figure 1c), while the samples from Farm A did not
Based on the current public Multi-locus sequence typing (MLST) database, all three of these sequence type (ST) have previously been reported from Thailand, with ST392 and ST51 reported to have been discovered in water samples collected in southern Thailand around 50 years ago [7,8]

Summary

Swine Melioidosis

Melioidosis, an infection endemic to Southeast Asia, northern Australia, and other tropical areas, is caused by the soil-dwelling Gram-negative bacterium Burkholderia pseudomallei, which is known to contaminate water sources [1]. Choy and colleagues reported three possible zoonotic cases in Australia including a butcher who directly handled infected meat or animals [2]. One pig in the group was discovered to have a liver infection, later confirmed as melioidosis by bacterial culture. The infection was identified as a result of two large abscesses in the liver observed during meat inspection (Figure 1a). Melioidosis in a pig linked to B. pseudomallei in the and water supply. Two large liver abscesses pig were discovered an unprotected abattoir worker in in December. December 2017 (a), and B. pseudomallei was isolated in pure culture on Ashdown’s agar (b). Water and soil from this farm cultured B. pseudomallei (c,d, respectively) possessing the same sequence collected type from392this farm cultured. Note: *, a confirmed B. pseudomallei colony grown from soil (d)

Environmental Source of the Infection and Additional Cases

Serological Surveys

Discussion

Conclusions