The detection of cases of probable hantavirus infection in patients who had presented with leptospirosis-like symptoms in Thiruvananthapuram is a warning signal that the health system needs to be more aware of the dangers posed by new pathogens.

Even as the Health Department, the National Institute of Virology (NIV), and the Rajiv Gandhi Centre for Biotechnology (RGCB), which detected hantavirus in a serum sample, are engaged in a war of words over its presence in Kerala, it remains a fact that public health officials have been consistently warned about the possibility of hantavirus in circulation in the State. The increasing number of patients dying of suspected leptospirosis and scrub typhus patients, presenting with symptoms akin to leptospirosis, has been a topic of discussion among the Health Services fraternity.

“The topic had again been in focus in 2012 when a private hospital in the city had reported a suspected hanta death. Instead of being in denial, the health authorities should make use of the facilities for virology studies and molecular diagnosis in the State to conduct sero-surveillance studies,” a senior public health expert told The Hindu.

In 1999

Serological and clinical evidence of hantavirus infection in India — and in Kerala — was documented in 1999 when serum samples from Kochi were sent to the Laboratory of Clinical and Epidemiological Virology at the University of Leuven, Belgium, to test for hanta. “We do not know for sure but it is very much possible that many suspected leptospirosis deaths in Kerala could actually be due to hanta. Hantavirus infecton should be the main differential diagnosis for leptospirosis,” said Georgy Ninan, consultant nephrologist in Kochi, who had in 1998, found serological proof for clinically suspected hantavirus infections in Kerala.

Similar symptoms

“The clinical symptoms of leptospirosis and hantavirus infection are very similar, with acutely ill patients going into renal failure and pulmonary haemorrhage. We had a number of patients with leptospirosis symptoms but negative lab tests, dying on the fifth or sixth day of illness, making us suspect that this was hantavirus in play,” Dr. Ninan said.

“Thus, in 1998-99, we did a prospective sero-survey of 30 Kochi patients, whose blood samples were sent to the Belgium institute. Two cases were found to be hanta positive in the IgM and IgG antibody test. The hanta serotype identified were Seol virus (SEOV) and Puumala virus (PUUV),” he added.

A test is lacking

Despite serological evidence, no case of hantavirus has yet been documented in India and there is little information on the circulating types, primarily because a proper confirmatory test for hantavirus has still not been evolved. “Serology is the mainstay of diagnosis of hantavirus infections as the viremia (presence of virus in blood) in patients with haemorrhagic fever and renal syndrome is shortlived. Immunoflourescent Assay (IFA) or New Capture Elisa, a test being developed, are the best bet for detecting hantavirus,” Sara Chandy, a former virology researcher with CMC Vellore and one who has been doing extensive research on hantavirus in India, told The Hindu. Sero-epidemiological studies published by Dr. Chandy has pointed to a 4 per cent sero positivity of hantavirus infections in India. “Till date, no well-documented hantavirus case, as defined by virus isolation or molecular diagnostic evidence, has been reported in India. But it is a proven fact that one or more types of the virus is circulating in India. Co-transmission or co-infection of hanta with leptospirosis or scrub typhus is a real possibility, which has been documented and physicians should observe clinical symptoms closely,’’ Dr. Chandy said.

No infection: NIV

There is no hantavirus infection in Kerala, as per a report given by the NIV to the Health Secretary. This was stated in a press note issued by the Health Minister.

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