Epidemiology of melioidosis in an oceanarium : a clinical, environmental and molecular study
Abstract of thesis entitled
Epidemiology of Melioidosis in an Oceanarium: a Clinical, Environmental and Molecular Study
Reimi E. Kinoshita
for the degree of Master of Philosophy
at the University of Hong Kong
in February 2003
Melioidosis is a disease of animals and man caused by the Gram-negative bacterium, Burkholderia pseudomallei. The disease is endemic to Southeast Asia and northern Australia where the organism, a free-living environmental saphrophyte, can be isolated from soil and/or water. The first report of melioidosis in Hong Kong was from an outbreak among dolphins at an oceanarium, Ocean Park (The Park) in 1975. Many animals of different species at this facility have since died from this disease, especially marine mammals.
An epidemiological study was conducted to identify factors that might influence the development of melioidosis in animals at The Park and consisted of: reviewing clinical cases of melioidosis at The Park; examining circumstances in which these cases occurred; screening the environment both within and outside The Park for the organism; and molecular characterization of isolates to determine their inter-relatedness. At least 49 cetacean, 31 pinniped, 16 bird and 5 terrestrial mammal cases of melioidosis have been seen at The Park over 28 years and showed a strong seasonal distribution. This disease has been associated with over 35% of mortalities of marine mammals. The acute septicaemic form was the most common manifestation of melioidosis. The isolation rate of B. pseudomallei was 2.2% from water and soil collected within The Park and 1.6% when collected from different areas of Hong Kong. The organism was also isolated in The Park from rainwater during a typhoon. Pulsed-field gel electrophoresis demonstrated only two patterns (called A and B)
Word Count = 370 words
among 53 clinical and environmental isolates from The Park and seven isolates from soil in Hong Kong. Four patterns (A, B, C and D) were represented in nine isolates from affected humans in Hong Kong.
The findings of this study suggest that strong winds during inclement weather may carry the organism from distant sites and expose susceptible hosts. Marine mammals appear to be especially susceptible. The identification of only two genotypes that have remained stable over 28 years within The Park and in Hong Kong's environment suggests that either B. pseudomallei has been introduced into Hong Kong or these strains persisted as they are better adapted to the local climate than other genotypes. Further research examining the association of climatic conditions and the occurrence of melioidosis is recommended.
Word Count = 370 words
School:The University of Hong Kong
School Location:China - Hong Kong SAR
Source Type:Master's Thesis
Keywords:melioidosis china hong kong epidemiology molecular aspects
Date of Publication:01/01/2003