A cross-sectional study of Angiostrongylus malaysiensis in rats and gastropod hosts from recreational parks in Kuala Lumpur, Malaysia: Detection, risk factors and pathology.

Angiostrongylus malaysiensis is a potential zoonotic parasite, which reported to co-occur with A. cantonensis in human cerebrospinal fluid. It is a heteroxenous nematode that primarily develops through the early larval stages in gastropods and attains sexual maturity within rats. This study was conducted to determine the host species responsible for the reservoir of A. malaysiensis and investigate the risk factor for transmission among the hosts in Kuala Lumpur, Malaysia. Sampling was conducted in six recreational parks. The rats were trapped alive using steel wire traps with bait, while the gastropods were collected by active searching. The rats were euthanized and dissected to collect any adult worms observed. The molecular detection of A. malaysiensis was performed by PCR on gastropod tissue samples. Biotic and landscape factors were recorded for risk factor analysis. In total, 82 rats and 330 gastropods were collected throughout the study. Overall, 3.64% of gastropods and 32.9% of rats were infected with A. malaysiensis. Rattus tiomanicus (Malayan wood rat) and Parmarion martensi (Yellow-shelled semi-slug) were found as important hosts for A. malaysiensis. Host species, sampling site and macrohabitat type are risk factors associated with the prevalence of A. malaysiensis infection in rats. For gastropods, host species and sampling site are risk factors that correlate with the parasite detection. In total, 128 adult A. malaysiensis were recovered from the infected rats. The mean intensity of infection with adult A. malaysiensis was 4.65 for Rattus rattus complex and 4.90 for R. tiomanicus. Adult worms were found in the pulmonary artery or right ventricle, while eggs and first-stage larvae were found in capillaries of the caudal lung lobe. Infected lungs showed extravasated red blood cells in the alveolar spaces. The pulmonary arteries in the infected lung lobe were thickened. Kepong Metropolitan Park is the hotspot area for A. malaysiensis in Kuala Lumpur. These results provide essential information for public health officials to develop targeted interventions to reduce the transmission of A. malaysiensis in urban areas, particularly in recreational parks.

A Multi-landscape Assessment of Leptospira Prevalence on a Diversity of Small Mammals.

Leptospirosis is a major zoonotic disease, especially in the tropics, and rodents were known to be carriers of this bacterium. There was established information on Leptospira prevalence among animal reservoirs in human-dominated landscapes from previous literature. However, there was very little focus given comparing the prevalence of Leptospira in a wide range of habitats. An extensive sampling of small mammals from various landscapes was carried out, covering oil palm plantations, paddy fields, recreational forests, semi-urbans, and wet markets in Peninsular Malaysia. This study aims to determine the prevalence of pathogenic Leptospira in a diversity of small mammals across different landscapes. Cage-trapping was deployed for small mammals' trappings, and the kidneys of captured individuals were extracted, for screening of pathogenic Leptospira by polymerase chain reaction (PCR) using LipL32 primer. Eight microhabitat parameters were measured at each study site. Out of 357 individuals captured, 21 (5.9%) were positive for pathogenic Leptospira of which recreational forest had the highest prevalence (8.8%) for landscape types, whereas Sundamys muelleri shows the highest prevalence (50%) among small mammals' species. Microhabitat analysis reveals that rubbish quantity (p < 0.05) significantly influenced the Leptospira prevalence among small mammals. Furthermore, nMDS analysis indicates that the presence of faeces, food waste, and exposure to humans in each landscape type also were linked with high prevalence of pathogenic Leptospira among the small mammals. This study supplements previous studies on pathogenic Leptospira prevalence across different landscape types, and the major microhabitat factors associated with Leptospira prevalence. This information is crucial for epidemiological surveillance and habitat management to curb the possibility of the disease outbreaks.