Waterborne monster

A lethal marine bacterium, Vibrio vulnificus, could become a major threat to coastal populations, with warmer oceans and high rainfall creating ideal condition for its proliferation

- ROHINI KRISHNAMURTHY

CHANCES ARE that Vibrio vulnificus cases are underreported in India," says Lekshmi N, a researcher at Translational Health Science and Technology Institute, Faridabad. While pursuing a PhD at Rajiv Gandhi Centre for Biotechnology in Kerala in 2019, Lekshmi and her colleagues heard of a 55-year-old man in Thiruvananthapuram district who had developed a painful swelling in his right leg. The swelling lead to gangrene, then septicaemia, and the patient died within 24 hours. Curious about the case, the researchers managed to get his blood sample from the hospital where he was treated and identified Vibrio vulnificus as the microorganism responsible for the death.

People can get V vulnificus by eating infected raw shellfish (which results in diarrhoea, vomiting, fever) or by exposing wounds to waters where the bacteria live (which can cause life-threatening flesh-eating disease that kills about 20 per cent of the infected in one or two days).

The Kerala case was India's only sixth case of V vulnificus since 2007, and seventh till date, as per data collected by Down To Earth from case reports in peer-reviewed journals. Experts, however, believe that the number could increase significantly in coming years.

These pathogens thrive in the tropics or subtropics, where sea or brackish water temperatures reach 20°C or higher (see 'Marine threat'). They also prefer waters with low salinity. As climate change increases the frequency and intensity of cyclones, rain and flooding, coastal communities across the world could face a higher risk of exposure to V vulnificus. High rainfall also reduces salt levels in the sea, which suits the bacteria.