Times of India
11, March 2010
By Arun Ram
Chennai, India

In what could be the first case of Ross River fever in India, a 15–year–old boy from Villupuram district in Tamil Nadu has tested positive for the virus considered endemic to Australia and Papua New Guinea, a Chennai lab funded by the Department of Biotechnology (DBT) has said. Meanwhile, the state health authorities have dismissed the results, since the tests were not conducted under the Indian Council of Medical Research (ICMR).

Several cases of ‘mystery fever’ have been reported from clusters across the state since October, 2009. While many of them showed symptoms of chikungunya, tests ruled out the viral infection, leading to suspicion that it could be Ross River fever, another mosquito–born disease showing similar symptoms. Now, the Bioinformatics Infrastructure Facility Centre of DBT attached to Presidency College, Chennai, says it has found one positive case of Ross River fever and two equivocal (borderline) cases.

“Of the first ten blood samples we tested, one sample was found to be clearly positive for Ross River virus as the index value was 1.32 which is much above the minimal cut–off value for positivity (1.1) as recommended by Panbio (manufacturer of Ross River testing kit). The positive case can be considered the first serologically detected report of Ross River infection in Tamil Nadu as well as India,” S Rajarajan, the lab coordinator told TOI.

The sample of the boy who tested positive was collected on January 22, 2010. Samples that showed values of 0.99 (a 23–year–old woman), 0.94 (a 13–year–old boy) are considered equivocal, which does not rule out infection, Dr Rajarajan added. All the ten samples were collected from patients of Kallakuruchi in Villupuram, who complained of swelling of limbs, headache, backache and pain of multiple joints – all symptoms of chikungunya and Ross River.

The Kallakurichi clinic tested several samples at its lab, Computer Diagnostic Centre, and sent more than 100 samples, which did not yield conclusive results to bigger labs. But director of public health S Elango, dismissed the test results. “We had sent 42 samples collected from different parts of the state to Singapore and none tested positive for Ross River,” Elango said.

Virus–vs–Virus

• Both Ross River and chikungunya viruses belong to the same family (alphavirus)
• Both show similar symptoms including joint pain, fever and headache
• DPH says the Ross River positive could be a case of mistaken chikungunya
• Virologist says the kit used was Ross–specific and approved by WHO