Effect of Socio-environmental Factors on Rat Proliferation andLeptospiraTransmission in Suburban Areas of Dungun, Terengganu, Malaysia
Authors: Zamri Mohammad Izuan Mohd , Shafie Nur Juliani , Ali Mohammad Ridhuan Mohd , Awoniyi Adedayo Michael , Argibay Hernan Dario , Costa Federico 
Published: July 2023

Background

Rats play a significant role as important reservoirs in the transmission of neglected zoonotic diseases, such as leptospirosis, particularly in poor urban and suburban communities of Low and Middle-Income Countries. Their proliferation is influenced by poor socio-environmental conditions like poor housing conditions, improper refuse disposal, and open sewer which generally furnish rats with food, water and harborage sources. Several interventions have been targeted against rats, given their public health menace but with no significant success, probably due to insufficient knowledge about context-specific factors influencing their proliferation in poor environments.

Methodology/Principal Findings

We evaluated the effect of different socio-environmental conditions on rat proliferation and the possible outcome on the transmission ofLeptospirain suburban environments. We performed ten trapping sessions between April 2021 and January 2022, and captured 89 small mammals from 1385 trapping efforts (specifically,Rattus norvegicus(n = 39),Rattus rattus(n = 27),Rattus exulans(n = 10),Suncus murinus(n = 11), andTupaia glis(n = 2)), with a 15.7% (n = 14/89) of the captured animals testing positive forLeptospirabacteria using PCR detection. We used a generalized linear model to evaluate the effect of different socio-environmental variables on household rat infestation and reported residences without paved floors, the presence of animals/pets, residence type and residences with vacant lots as variables positively associated with rat proliferation in the study sites.

Conclusion

Rats are widely and differentially distributed in the poor communities of Dungun. BesidesR.norvegicusandR.rattus,S. murinus and T. gliscould also maintain and encourage pathogenicLeptospiratransmission in the study areas. To adequately control rats proliferation and subsequent human zoonoses transmission, it will be critical to advocate and promote appropriate infrastructure and urban services, together with good hygiene practices to reduce rats’ access to water, food and harborage.

Author Summary

Rats are important reservoirs in the transmission of urban and suburban leptospirosis, and their proliferation is generally supported by poor socio-environmental conditions. Despite the strong association between poor socio-environmental conditions, rat proliferation and leptospirosis transmission, few studies have characterized their relationships in many poor suburban environments. Therefore, we evaluated the effect of different socio-environmental conditions on rat proliferation and possible effect on leptospirosis transmission in suburban communities of Dungun, Malaysia. We performed rat trapping and captured 89 small mammals from three orders, with a 15.7% (n = 14/89) of the captured animals testing positive forLeptospirabacteria using PCR detection. Using a generalized linear model, we reported residences without paved floors, the presence of animals/pets, residence type and residences with vacant lots as variables that are positively associated with rat proliferation in the study sites. Our findings show that rats are widely distributed in the study sites, and that in addition toR.norvegicusandR.rattus,S. murinus and T. gliscould also maintain and transmit pathogenicLeptospira. Given the variables associated with rats proliferation, it is crucial to promote appropriate infrastructure and good hygiene practices to reduce rats’ access to water, food and harborage and subsequent rodent-borne diseases.