Scrub typhus in Odisha: Changing climate may have a role behind outbreak, says expert

Six deaths reported in western Odisha, Himachal’s Shimla reports nine fatalities

By Hrusikesh Mohanty
Published: Thursday 14 September 2023
Photo: iStock

A resurgence of scrub typhus cases in Odisha has brought forward the role of climate in driving up the rate of the highly infectious disease. At least six deaths due to the disease have been reported since September 1, 2023 from the western parts of the state — five in Bargarh district and one in Sundargarh district, according to official sources.

Scrub typhus is caused by a zoonotic rickettsial bacterium called Orientia tsutsugamushi, which is transmitted to humans through the bites of infected mites in the larveal stage called chiggers. The symptoms of scrub typhus commonly include fever, headache, body ache and sometimes a rash.

In severe cases, the infection can lead to respiratory distress, brain and lung inflammation, kidney failure and multi-organ failure, ultimately resulting in death, said Uma Shankar Mishra, a medicine specialist.

The disease has been reported in states like Himachal Pradesh as well, where at least nine persons succumbed to the infection in its Shimla district and 295 have been infected, sources said.

In Odisha, of the five deaths reported from Bargarh, two cases were from Sohela block, while the rest were from Attabira, Bheden and Barpali blocks, said Additional District Medical Officer for Bargarh Sadhu Charan Das. Four others in the district were found to be positive for scrub typhus, however, they have been treated, he said.

At least a dozen more are undergoing treatment for scrub typhus at Veer Surendra Sai Institute of Medical Sciences and Research (VIMSAR), Bural. “So far, we have tested at least 30 positive cases for scrub typhus in VIMSAR,” said Sankar Ramchandani, assistant professor, Department of Medicine. The condition of all of them are stable or cured, he said.

The disease is not new for Odisha — four years ago, the disease was reported in Koraput, Nabarangpur, Keonjhar and Sundargarh districts, said Niranjan Mishra, state public health director. Bargarh and Sambalpur districts had experienced a scrub typhus outbreak in 2014 and 2000, respectively, said Ramchandani. Fortunately, no casualties were reported.

Read more: Mystery behind Gorakhpur encephalitis deaths: is scrub typhus the likely cause?

Mites carrying the disease are generally found in the bush, jungle and paddy areas, so the disease is also called jungle or bush typhus. Ramchandani said western Odisha districts have more agricultural and forest land suitable for mites, which might be one of the reasons behind the outbreak. However, a warming planet and changing climatic conditions may be playing a role as well, he said.

A 2022 study looked into clustering of scrub typhus cases in children in three contiguous administrative districts in South India over five years. It found temperature, humidity and rainfall had a major role in the incidence of scrub typhus. 

A 2017 study looking into scrub typhus cases in China also found that a 1 degree Celsius increase in mean temperature was associated with a 3.8 per cent increase in the odds of scrub typhus cases during the same week.

The chiggers that transmit the disease generally live in low temperature and high humidity conditions, said Ramchandani.  This year, Odisha, particularly the western districts, experienced the particular climatic condition favourable for the mites, he said.

These mites acquire the infection during their larval stage from wild rodents or other small animals and then pass it on to humans when they bite, said Mishra. The mites are in their larval stage from July to October and most India states remain low temperature and high humidity during the period.

Treatment at an early stage of the disease is important to avoid fatalities, he said, adding Elisa tests for scrub typhus were available in all district public health laboratories of all the district  headquarter hospitals in the state.

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