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As a proof of concept, we set out to identify the role of phages in identifying hotspots for typhoid fever. We also analysed the cost-effectiveness. Phages can play a crucial role in pathogen surveillance in resource-limited settings
Typhoid fever remains a major cause of death despite notable advances. According to a study that analysed deaths related to Antimicrobial resistance in 2019 showed that Salmonella typhoid is the 11th major cause of death globally
Figure 1: Global deaths (counts) attributable to and associated with bacterial antimicrobial resistance by pathogen, 2019(Source).
Conventional population-based studies on typhoid prevalence are often hindered by geographical and temporal limitations, highlighting the urgency for innovative surveillance methods. Although it is well known that contaminated water plays a significant role in typhoid transmission, identifying the causative organisms, particularly S. Typhi, has proven difficult when using traditional culture methods on water and other environmental samples.
In recent years, the primary approach for detecting S. typhi in the environment has changed to molecular methods involving the detection of S. typhi DNA. This strategy, however, requires access to molecular laboratory facilities and competent workers, with anticipated expenses per sample in the hundreds of dollars.
In my previous post, I argued in favor of phages as a tool for identifying hotspots for Salmonella typhi. My undergraduate students set out to identify hotspots for Salmonella in the three geo-political zones of Plateau State, Nigeria
We undertook to identify hotspots of Salmonella typhi in some communities in Plateau State. A total of 31 water sources were sampled, and phages specific to S. typhi were isolated from the water sources (Figure 1). From our study, we found that river water is the leading driver of typhoid fever in rural communities in Plateau State (Figure 3).
Our workflow
Figure 2: Phage isolation protocol
As expected, River water is the driver of typhoid in rural communities in Nigeria.
What this cost us
Petri Dishes 2 USD/20 plates
Media 50 USD/500mg
Syring filter 20 USD for 10 filter
When compared to the cost of Environmental isolation and molecular detection, Phages based surveillance is cheaper.
Phages can be adopted in resource-limited settings to monitor disease outbreaks and can be used in wastewater monitoring. We hope to evaluate this model for Cholera and other enteric bacteria.
