Submitted by: Renard M Jamora 2017-07-06 00:00:00 Last Updated by: Renard M Jamora 2018-03-17 10:58:24 Export to PDF

Leptospira: Seroprevalence in Sewer Workers and Rats and Environmental Presence in Selected Cities of Metro Manila, Philippines 

PHRR170707-001590

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Leptospira: Seroprevalence in Sewer Workers and Rats and Environmental Presence in Selected Cities of Metro Manila, Philippines 

This study will determine the seroprevalence of Leptospira in consenting sewer workers and rats and its presence on the sewer workers’ environment, limited to sewer water and soil, in the West Zone of Metro Manila, Philippines. Microscopic agglutination test will be performed to determine Leptospira-agglutinating antibodies on serum samples of sewer workers and rats while serotyping of possible Leptospira isolates on sewer water and soil samples will also be conducted. Amplification of the Leptospira 23S rRNA gene (rrl) and flagellin B gene (flaB) will be performed through polymerase chain reaction (PCR) to directly determine the presence of genus Leptospira and detect pathogenic leptospires, respectively, in the kidney of rats and environmental samples. Possible Leptospira isolates will be serotyped using available polyclonal antibodies only.

The study will be composed of apparently healthy sewer workers with informed consent employed for not less than six months by a single water services company in the West Zone of Metro Manila. Therefore, the future findings of the study cannot be generalized to other sewer workers outside Metro Manila due to differences in working conditions, situations, locations and the like. Furthermore, soil and sewer water samples will only be collected at a 100 m radius from a sewer system manhole specifically serviced by the water services company in collaboration with.

Start Date Duration in Months Target Completion Date Actual Completion Date
2017-03-01 12 2018-03-01 2018-03-01

Ongoing

Institution Classification Region LTO #
University of the Philippines - Manila, College of Public Health, Department of Microbiology Public Higher Education Institution - State Universities and Colleges NCR
Institution Amount Region
Department of Science and Technology N/A NCR
Maynilad Water Services, Inc. N/A NCR
Name Expertise Affiliation
Nina G. Gloriani, MD, MS, PhD Microbial Immunology University of the Philippines - Manila, College of Public Health, Department of Microbiology
Sharon Villanueva, MD Microbial Immunology University of the Philippines - Manila, College of Public Health, Department of Microbiology

Leptospirosis is a zoonotic disease caused by the infection of pathogenic Leptospira species that threaten human health, the bovine and swine industries around the world, and other wild and domestic animals. The genus Leptospira belongs to the family Leptospiraceae that consists of saprophytic and pathogenic groups. According to their antigenic structure, Leptospira can be classified into serovariants. The genus Leptospira includes 20 species with more than 250 pathogenic serovars that are organized in 24 described serogroups (Villanueva et al, 2014).

Leptospirosis is a major public health issue in many countries, especially in Latin America and South-East Asia (Picardeau, 2013) including the Philippines. Many Filipinos are infected with Leptospira. Outbreaks are prominent in the months of June to November, which is the Philippines’ rainy season, and just after these months in flood-prone areas. Unofficial reports have also suggested outbreaks occurring during the dry season especially in the rural areas (Villanueva et al, 2014). The incidence of infection is significantly higher in warm-climate countries than in temperate regions. This is due mainly to longer survival of leptospires in a warm and humid environment which are characteristics of most tropical and developing countries, hence greater exposure to leptospirosis for its human population (Levett, 2001). Water and soil contaminated with the urine of leptospiruric animals is the source of the pathogenic leptospires, and the role of water as a vehicle of transmission of this organism is very essential (Henry and Johnson, 1978).

Rodents, specifically rats are the most important reservoirs of Leptospirosis. They harbor Leptospira in their kidneys, continuously shed the organisms in their urine, and contaminate the environment (Villanueva et al, 2014). In 2010, a local study conducted by Villanueva et al reported that 98% of rats captured in Metro Manila and Laguna tested positive for Leptospira antibodies. Based on their findings, most of the rats had antibodies against serovars Manilae, Hebdomadis, and Losbanos.

Leptospirosis is an occupational risk both in rural and urban settings. Vulnerable groups include (but are not limited to) farmers, abattoir workers, veterinarians and sewer workers (Zavitsanou and Babatsikou, 2008). In 1995, De Seres et al reported that sewer workers have higher prevalence of Leptospira antibodies than controls from the general population. In 2004, sewer workers in Pune were studied and were found to have past exposure to different species of Leptospira. Exposure among sewer workers were more likely due to the nature of their occupational activities such as routine exposure to drains and sewers which are most likely contaminated with rodent excreta (Tiwari, 2008).

 

Sera samples for sewer workers and rats:

Serum Antibody Positivity for Leptospiral antigens through Microscopic Agglutination Test 

Rat kidney and environmental samples:

Culture positive

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Completed

  • Philippines

Non-clinical Studies

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01 Mar 2017

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