Risk of adenovirus and Cryptosporidium ingestion to sanitation workers in a municipal scale non-sewered sanitation process: a case study from Kigali, Rwanda

Abstract

Sanitation workers provide essential services that protect public health, often at the cost of their own health and safety. In this study, we evaluate occupational exposure to fecal pathogens at each stage in a non-sewered sanitation process. Bulk fecal waste samples were collected during waste collection and waste processing tasks and analyzed for Cryptosporidium, adenovirus, E. coli, and total coliforms using quantitative polymerase chain reaction and culture methods. Structured observations of worker hand-to-mouth behavior were conducted, and worker hand- and glove-rinse samples were collected and analyzed for E. coli and total coliforms. A Monte Carlo simulation was used to model the dose of pathogen ingested and the risk of disease across two waste collection and processing tasks. The model results show that the probability of disease was highest from exposure to adenovirus during collection. Our analysis highlights that pathogen-to-indicator ratios are useful for predicting the risk to adenovirus which has a high detection rate. On the other hand, the use of pathogen-to-indicator ratios to predict Cryptosporidium concentration is fraught due to variable detection rates and concentration. HIGHLIGHTS This study outlines methods for conducting quantitative microbial risk assessments in low-resource settings.; Pathogen-to-indicator ratios specific to this study are constructed from primary data in order to minimize model uncertainty.; The probability of pathogen infection and disease was estimated for sanitation workers at each stage in a municipal scale fecal waste collection and waste-to-fuel process.;

Keywords

• occupational exposure
• quantitative microbial risk assessment
• resource recovery
• rwanda
• sanitation workers
• urban sanitation