By Gift Briton

Researchers have found that wastewater can be used to detect the presence of bacteriophages- virus-killing bacteria- to determine areas where typhoid fever infection is most common.

This is according to a recently published research study by the Child Health Research Foundation in the open-access journal, PLOS Neglected Tropical Diseases.

Typhoid fever is a common infection in many low- and middle-income countries and causes an estimated 135,000 deaths and 14 million infections globally each year.

The World Health Organization (WHO) has prequalified two typhoid vaccines, but for policymakers to plan effective vaccination strategies, they need accurate, high-resolution estimates of where the burden is highest.

Traditionally, people have cultured the bacterium that causes typhoid fever from blood samples to determine where the infection is most common. However, in the new study, researchers tried a more cost-effective surveillance approach. They tested wastewater samples from different locations to detect bacteriophages specific to the water-borne pathogen that causes typhoid fever, Salmonella Typhi.

The team tested 303 water samples from two locations in Bangladesh: the urban capital city, Dhaka, and a rural district, Mirzapur. They found that bacteriophages specific for Salmonella Typhi were present in 31% of samples in Dhaka, compared to just 3% of samples from Mirzapur. This corresponds to results from more than 8,400 blood cultures, in which 5% of cultures from Dhaka and 0.05% from Mirzapur tested positive.

The new results suggest that detecting bacteriophages specific to Salmonella Typhi may be a rapid environmental surveillance method that could help decision-makers understand the presence of typhoid fever in the community. The researchers propose that environment monitoring of bacteriophage could be a simple, cost-effective and scalable tool to assist policy decisions on typhoid control.

Environmental phage surveillance can be used to estimate typhoid in other countries, including in Sub-Saharan Africa where limited epidemiological data on typhoid fever is available. Environmental phage surveillance may be also applied to map routes of disease transmission by focusing on wastewater in the region.

‚ÄúThis tool, combined with traditional blood culture surveillance, can generate community-level data to evaluate the impact of interventions including the introduction of typhoid vaccines, water improvement projects, and sanitation and hygiene systems,” the research reads.