Diarrhoea-causing pathogen becoming prevalent in Kolkata, prevention & control strategies needed: Study

A pathogen associated with diarrhoea is circulating in Kolkata, according to a new study. 

The pathogen in question is Entamoeba moshkovskii. First described in 1941 in Moscow, it is commonly found in anoxic sediments (oxygen deficient) to brackish coastal pools. 

“The findings reveal the epidemiological significance of E. moshkovskii infection in Eastern India as the first report in this geographical area and expose this species as a possible emerging enteric pathogen (causes intestinal infections) in India,” the authors wrote in the report published in journal PLOS Neglected Tropical Diseases.

The pathogen has been reported in countries such as the United States, Italy, Iran, Turkey, Bangladesh, India (Puducherry), Kenya, Australia, Indonesia, Colombia, Malaysia, Tunisia, Tanzania and Brazil.

E moshkovskii and other related species like E histolytica and Entamoeba dispar are morphologically identical. They also cause amoebiasis, which affects approximately 50 million people in tropical regions and causes nearly 100,000 deaths annually.

Of them, E histolytica infections are prevalent. However, the researchers speculate that this is overestimated as this pathogen is morphologically indistinguishable from other related species.

Previous studies have also not carefully investigated the endemicity of E moshkovskii, the paper stated.

Also, there are limited studies on the genetic and phylogenetic characterisation (its evolutionary relationships with other organisms) of E moshkovskii in India.

So, researchers from India and Japan conducted a surveillance study from March 2017 to February 2020. They collected faecal samples from 6,051 diarrhoeal patients from ID Hospital and BC Roy Hospital, Kolkata.

They then extracted the DNA and carried out polymerase chain reaction (PCR) tests and sequencing as well as used microscopy to identify the species. 

Their analysis showed that 4.84 per cent of patient samples tested positive for Entamoeba species. Of them, 3.12 per cent were infected with E moshkovskii.

This, the researchers wrote, means that 1.72 per cent of patients were infected with other Entamoeba species in the study area.

Further, 19.04 per cent of E moshkovskii infections could not be identified using microscopy but a PCR test could catch them.

E moshkovskii was significantly more prevalent than E histolytica throughout the three years of the study, with a decreasing trend of E histolytica infection in the last few years around Kolkata.

Children were found to be more susceptible. The prevalence was the highest among those aged 5-12 and lowest among 19-29 age groups.

“The higher prevalence of E moshkovskii in this age group might be associated with their lack of health education regarding hygiene practices,” the authors noted. 

The infections also appear to be seasonal. The researchers observed a spike in summer and post-fall seasons. These results, the authors explained, required further detailed investigations.

The analysis also revealed that a richly diverse population of E moshkovskii species are distributed in Kolkata and adjacent areas.

The researchers recommended more studies to understand how this pathogen spreads and call for a proper diagnosis to avoid the emergence of drug-resistant strains.

“It also highlights the need for public health authorities to implement prevention and control strategies,” they wrote.

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