Molecular and serological detection of Leptospira interrogans among wild rats in flood-prone residential areas of Indonesia.

Abstract

Background: Indonesia is a tropical country with heavy rainfall, mostly in low-lying areas. Floods are one of the most common natural disasters in Indonesia, with climate change causing continuous flooding in some regions. The spread of human pathogens as a severe consequence of flooding, such as Leptospira, which may cause Weil's disease, is a concern for public health.

Aim: In this cross-sectional study, we compared DNA from the rat kidney to serum samples to identify pathogenic Leptospira using polymerase chain reaction (PCR) amplification to promote a less invasive method of collecting samples from the rat vectors.

Methods: Fifty-nine rodents inhabiting highly populated, flood-prone suburban regions were captured inside and outside houses. Following DNA extractions, we analyzed the quantity and quality of DNA concentration from the kidney and serum specimens using a nanophotometer. The lipL32 gene was amplified to detect the pathogenic Leptospira.

Results: The mean value of kidney DNA was 151.67 ng/µl with an average A260/A280 value of 1.836, whereas the mean value of serum DNA was 22.08 ng/µl with an average A260/A280 value of 1.233. Twenty (33.9%) kidney DNA and 10 (16.9%) serum DNA samples showed the target DNA (lipl32). The multiple sequence alignment analysis revealed the lipL32 sequences homology to Leptospira interrogans ser. Copenhageni.

Conclusion: Rat kidneys exhibited higher DNA amount and purity than the serum. Moreover, the PCR detection of lipl32 revealed higher positive results in kidney DNA than serum DNA samples, with high similarity to L. interrogans lipl32 sequences. Therefore, the kidney remains a better DNA source than serum for the molecular analysis of Leptospira in rats.