The infectious condition scrub typhus is rearing its head in West Bengal state capital Kolkata, sparking concern among doctors in the city.
Scrub typhus is caused by being bitten by chiggers (larval mites) infected with the bacteria Orientia tsutsugamushi, which belongs to the Rickettsiaceae bacteria family. The disease is typically limited to rural areas, but the infections reported in Kolkata are believed to be locally sourced according to physicians who have reported that some of those who have contracted scrub typhus in the city have not travelled to rural localities.
“This indicates that they were locally infected, which means the chigger is now present in the city,” said Dr Debkishore Gupta, head of infection control and microbiology at the Calcutta Medical Research Institute (CMRI). “Even though the majority of scrub typhus patients are still from rural areas, the number of locally infected patients has risen significantly this year…we have been receiving one or two patients every week, who might have been infected locally.”
Identifying the reasons behind this trend, Gupta said “conditions conducive to the breeding of chiggers exist in Kolkata. That apart, a large number of people travel to the city from the rural areas every day and could well be carrying the insect inadvertently. Vehicles plying into the city could be transporting it as well. Those engaging in gardening are at risk, for the chigger thrives in grasses and undergrowth.”
Scrub typhus has captured attention in recent years after an extended period of relative obscurity, having faded from the public eye. A number of outbreaks have been reported. In 2016, 700 cases were reported in Himachal Pradesh leading to twenty deaths. Cases of the disease have been reported in Kerala. Cities are witnessing cases of the disease, including Delhi. In Kolkata, earlier this year, fifteen cases were reported, including two children.
“It’s possible the chigger has adapted itself to urban conditions,” noted Fortis Hospital consultant Dr Joydeep Ghosh in the wake of recent scrub typhus cases. “So, it could now be risky to assume that scrub typhus can strike only in rural areas.”
Underdetection is a risk, as the first symptoms of the disease “are identical to any viral infection, so it can be deceptive,” according to Gupta. “In case it’s not identified and antibiotics are not used, patients tend to deteriorate fast and may get meningitis or lapse into a coma. Sepsis is also common.” Other potential effects of untreated scrub typhus – which can be remedied with a course of the antibiotic doxycycline – includes respiratory distress, pneumonitis (inflammation of lung tissue), encephalitis (inflammation of the brain), kidney failure and possibly multiple organ failure.
The Center for Disease Control and Prevention in the United States says “the most common symptoms of scrub typhus include fever, headache, body aches, and sometimes rash.” If the disease goes undetected until a later stage, the risk of death increases compared to the normal mortality rate of two percent in scrub typhus cases. As such, private hospitals in Kolkata are conducting tests for scrub typhus in cases of fever – a move likely to be welcomed by experts.
“Scrub typhus is endemic in India. Right now scrub typhus is enjoying its status as a re-emerging disease and is often causing trouble in diagnosis due to absence of specific rash or eschar,” wrote Drs Dibyendu Banerjee, Atindra Kumar, Purba Mukherjee, and Shuvankar Mukherjee in a paper published earlier this year. “Scrub typhus should be considered at the earliest in the differential diagnoses for acute undiagnosed fever with nonspecific features in endemic countries like ours.”