New virus feared as many test negative for H1N1

Is a new flu virus variant in the air which is not H1N1? Too many patients are testing negative for H1N1, and this has become a cause of concern in Maharashtra. While some suspect that suppliers may be providing sub-standard testing medium, there is a serious worry that there is a non-H1N1 virus strain doing the rounds.

An analysis of deaths at Pune’s Sassoon Hospital revealed that about 30-35% of the patients who died due to H1N1 influenza showed strong clinical symptoms of the virus, but still tested negative. Even in Mumbai, about 12% of the cases had strong symptoms of swine flu but had tested negative.

Director of major hospitals Sanjay Oak said the BMC had written to the National Institute of Virology about this observation. “Recently, we lost two patients at Nair Hospital who had classic symptoms of swine flu, but tested negative,” he said. “It could be some variant of H1N1 but not classic H1N1, and so the tests are showing negative,” he said.

Echoing the same concern, Arun Jamkar, dean of BJ Medical College, Pune, said: “We have found that 36 patients who died in Sassoon Hospital had all the classic symptoms of H1N1 and had even responded to Tamiflu, but they tested negative for the virus”. He added that there were questions about the modality of collecting and testing the samples.

The testing protocol involves the collection of throat samples and letting them grow on the viral transport medium (VMT). The test could show false results if the medium is faulty. The VMT is a semi-solid agent that is distributed to laboratories by suppliers chosen by the NIV in Pune. Authorities of NIV could not be reached for comment.

Talking to DNA, the joint director of the Directorate of Medical Education and Research (DMER), Pravin Shingare, confirmed that the issue was discussed in one of the state’s high-level meetings. “Samples can test false negative or positive in many instances,” he said.

Explaining the findings, Shingare said the collection of samples was tricky. “Though one’s throat region is about 80-90 sq cm, only about 20-30% could be affected by the virus. So there is a high possibility that the swab is collected from an area not affected by the virus,” he said. Also, transportation of the samples could be an area of major concern. “If the temperature is not regulated as per the standard protocol, samples can get spoilt and produce wrong results,” he said.

Meanwhile, another state official said that the worst fear was that suppliers could be supplying sub-standard medium. “Some suppliers could be supplying routine medium even if they are provided money to provide the medium special for H1N1,” the officer said.

Director of Haffkine Research Institute Abhay Chaudhary, however, said that it was quite possible that the virus was not H1N1, but seasonal. “After all, both of them have the same symptoms,” he said. He added that of all samples tested in Mumbai for H1N1, as many as 20% tested positive for seasonal flu and about 25% for H1N1.