George M Varghese, professor at the Department of Infectious Diseases, Christian Medical College, Vellore, talks about scrub typhus, a re-emerging disease in India
More than 100 children have died in Gorakhpur since August 10. The peak in deaths was linked to the non-availability of oxygen at BRDMC. But children continue to die even now just as they were before oxygen shortage. Media reports suggest that the deaths could be due to scrub typhus, a disease cause by Orientia tsutsugamushi, a rickettsial group of bacteria. George M Varghese, professor at the Department of Infectious Diseases, Christian Medical College, Vellore, talks about scrub typhus, a re-emerging disease in India.
Is there evidence that the encephalitis in Gorakhpur is scrub typhus?
Scrub typhus is present everywhere in the country and it is quite likely that it is present there too. Recent investigations have shown that around 24 per cent of patients from Gorakhpur tested positive for scrub typhus. Studies done by the National Institute of Virology earlier suggested that around 15-20 per cent of the cases in Gorakhpur are due to Japanese encephalitis.
Subsequent to this, there was a huge vaccination campaign against Japanese encephalitis and the proportion due to this disease seems to have gone down. The disease has also been linked to the presence of an eneterovirus which spreads through water. It seems to be a mixture of illnesses. However, the major cause of the outbreak still remains elusive.
A large number of patients, mainly children, still seem to be getting affected with an encephalitic illness and a clear and complete picture has not emerged so far. While I have not been there to investigate the outbreak, I can say that the symptoms being reported are atyptical to scrub typhus. There are several reports of disease in infants. Infants are unlikely to have any exposure to vegetation, the mode of acquisition of scrub typhus. Although neurological involvement in terms of meningo-encephalitis in scrub typhus is seen, the picture emerging from this region is very atypical. The outcome in patients with scrub typhus and neurological involvement are seldom fatal.
What could be the reason for increasing cases of scrub typhus in India?
It is a re-emerging disease. Earlier, community sampling showed around 5 per cent serological prevalence of past infection, but now the prevalence is as high as 30 per cent. This re-emergence is visible in the rest of South East Asia too. The estimated burden of the disease in this region is around 1 million cases every year.
The disease caused significant morbidity and mortality during world war times and Indo-Pak conflicts. Subsequently, it became a rarity and for a long time, it remained off the radar. In the olden days patients with fever would be prescribed common antibiotics like tetracycline and chloramphenicol, which treats scrub typhus. But now, the commonly used antibiotics, such as cephalosporins, are ineffective against scrub typhus. Furthermore, clearing of forests/vegetation, increasing rodent population, which are the alternate host for the pathogen, as well as climate change, could be additional factors contributing to the re-emergance.
Does India have a policy for controlling the pathogen or treating the disease?
The ICMR developed guidelines for diagnosis and management of rickettsial diseases in 2015. We still have a long way to go. Researchers across the country, at institutes like PGI in Chandigarh and CMC, Vellore, are working on improving the diagnostics for scrub typhus and developing new diagnostics. We are starting a new multi-centre, multi-national randomised controlled trial, in high burden countries such as India, Thailand and Laos to evaluate the best treatment for severe scrub typhus funded by Wellcome Trust DBT alliance.
What can we do to protect ourselves from scrub typhus?
Doctors should be aware about the disease so that it is diagnosed early and treated appropriately. They are more aware now than before, but we still have a long way to go. When we started our work 15 years ago, the case fatality was around 15 per cent, now it is just around 5 per cent. The intervention has been very simple; early diagnosis and starting doxycycline which costs less than 200 rupees. The general public should be aware about the disease and how to protect themselves from the bite of the transmitting insect.
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