Identification of Leptospira spp. from environmental sources in areas with high human leptospirosis incidence in the Philippines

ABSTRACT

Leptospira is the causative agent of leptospirosis, which is considered an emerging major threat to public health due to its increasing frequency reported worldwide. In the Philippines, the prevalence of the disease continuously rises, particularly in urban areas. Because leptospirosis is commonly transmitted through contact with contaminated environment, water and soil samples were collected in regions in the Philippines where high incidence of human leptospirosis cases was reported recently. Of the 54 samples screened for the presence of Leptospira, 35% were found positive through 23S rRNA gene PCR-based detection. None were found positive when primers targeting lipL32, lipL41, and ompL1 genes were used. Most of these isolates were collected from rural areas. However, 16S rRNA gene sequencing identified all isolates to be L. yanagawae and L. meyeri, which are nonpathogenic. Despite the lack of evidence of the presence of pathogenic species in the environmental sources, the results still suggest that leptospires persist in these areas. These data are crucial for environmental monitoring and identification of contaminated areas where humans may be at risk of infection.

KEYWORDS:

• Leptospira
• leptospirosis
• environmental sources
• Philippines
• PCR detection
• 16S rRNA gene sequencing

Acknowledgments

The study was funded by a research grant from the Natural Sciences Research Institute of the University of the Philippines, Diliman (Project code: BIO-17-1-09). The funding agency had no role in the study design, data collection, and interpretation.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Natural Sciences Research Institute University of the Philippines Diliman [BIO-17-1-09].