Fifty-one Rickettsia tsutsugamushi isolates from small mammals collected in central Peninsular Malaysia serologically characterized by direct immunofluorescence using eight prototype strains. Karp-related (TA763, TA686, TA716) antigens were found in 90.2% of the isolates.
Leptospirosis, a widespread zoonotic disease, is a public health problem, especially in major urban centres, and is mainly reported to be associated with rats. In Malaysia, focus has been primarily given to the Leptospira prevalence in rodents per se, but there is lack of information on the microhabitat structure of the outbreak areas. We aimed to determine the diversity of small mammal species, microhabitat types, and their prevalence of pathogenic Leptospira spp. in the outbreak areas, which were categorized as urban, semi-urban, and recreational forests. Sampling involved deploying 100 to 300 live traps at each study site. Kidney samples were extracted from selected individuals, for screening of pathogenic Leptospira spp. by PCR. Out of 537 individuals from 15 small mammal species captured, 4 species were recorded from urban, 13 from semi-urban, and 11 from recreational forest sites. From 389 individuals screened, 58 were tested positive for pathogenic Leptospira. Recreational forests recorded the highest prevalence with 19.4% (n = 93), followed by urban, 16.6% (n = 163) and semi-urban sites with 9.8% (n = 133). Seven rodent species were tested positive for pathogenic Leptospira from all areas. R. norvegicus was found to harbour the highest prevalence (66.7%) in urban, R. rattus (53.8%) in semi-urban, whereby M. whiteheadi (44.4%) in recreational forest sites. Microhabitat analysis revealed that rubbish quantity contributed especially strongly to a high prevalence of Leptospira. This study contributes to understanding of the host and microhabitat preferences of Leptospira, which is important in controlling the spread of this disease in human's landscapes.
Leptospirosis is a zoonotic disease caused by bacteria of the genus Leptospira and most often acquired through contact with environments contaminated with leptospires shed in the urine of infected mammals. In urban environment, rodents are well-known as the main carriers of this bacteria, however there were no intensive study on the population structure of these animals, and how it associated with this disease. Hence, we use a case study from an outbreak in a residential area in Selangor, Malaysia, to investigate how community structure of small mammals, associated with the prevalence of Leptospira. One hundred cage traps were placed randomly in and around these houses in five phases with two months interval for a year. Community structures (species, sex, and age) were assigned for each individual, prior to screening for pathogenic Leptospira, using a partial lipL32 gene from the kidney samples. 185 small mammals from four species were captured, Rattus norvegicus (74.5%, N=138), R. rattus (20%, N=37), Tupaia glis (5%, N=9), and Suncus murinus (0.5%, N=1). From this number, 29 individuals were found PCR positive for pathogenic Leptospira (R. norvegicus, N=20; R. rattus, N=6; T. glis, N=2; S. murinus, N=1). The study shows that Leptospira occurrence in the small mammals were significantly correlated to age category and sampling phases, with Spearman Correlation (rs) p=0.02 and p=0.04 respectively. Adult individuals were significantly more prevalent with Leptospira infection, whereby March and June were found to associate with higher Leptospira prevalent among the small mammals, potentially coincide with low rainfall and relative humidity level. This information is important in designing a specific control method for rodents in Leptospira outbreak areas. In addition, intensive sampling and regular cleaning effort were found to significantly reduce the small mammal Leptospira reservoir, thus should be implemented in intervention strategies in the urban environment.
The rickettsial disease of man found only in Asia is mite-borne (scrub) typhus, caused by Rickettsia tsutsugamushi. Unique to southern Japan is a little-known human mononucleosis-like disease caused by Rickettsia sennetsu. In 1981 and 1982, there was a remarkable resurgence in the number of reported cases of mite-borne typhus in Japan after some years of virtual absence. Recent studies of R sennetsu have resulted in its reclassification to the genus Ehrlichia, members of which until now have been exclusively pathogens of animals. The historical background of ecologic investigations, in Malaysia and elsewhere, of these two developments suggest directions for future research.
Here, we investigated an outbreak of leptospirosis among reserve military recruits that occurred following a survival exercise in the Hulu Perdik forest within the Hulu Langat district, Kuala Lumpur, Malaysia. Blood samples from the 12 patients that presented symptoms for febrile illness on clinical examination were subjected to laboratory investigation, comprising Lepto IgM rapid test, IgM ELISA, and microscopic agglutination test (MAT). All these patients were interviewed for possible risk factors for leptospirosis. Rodent trapping and environmental sampling for possible isolation of leptospires in the outbreak site was performed. The isolated leptospires were genetically characterized and investigated for the potential epidemiological link with human leptospirosis. Among the 12 patients, two (2/12; 16.6%) were confirmed positive for leptospirosis by microscopic agglutination test (MAT with titers 400-800; serovar autumnalis and hardjobovis). Two Leptospira species from rodents (L. interrogans and L. borgpetersenii) and two from the environment (L. kmetyi and L. wolffii) were identified. The possible epidemiological link between human serovars and animal Leptospira species indicates rodents as the potential reservoir while the environment (soil and water) serves as a transmission route. This investigation highlights the robust presence of pathogenic leptospires on Malaysian environment and rodents which may present the risk of infection, especially among high-risk individuals. Hence, occupational risk individuals are cautioned to observe appropriate preventive measures including prophylaxis and seek immediate medical attention for any illness following similar activities.