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Times of India
03 February 2011
By Kounteya Sinha
New Delhi, India

Killer TicksKiller Ticks
The virus causing the deadly Crimea Congo Hemorrhagic Fever (CCHF) in Ahmedabad has jumped from infected ticks to local cattle like sheep, goats and cows. Cattle samples collected from six villages around ground zero – Kolat village in Sanand whose resident Amina Momin was the first human in India to get infected with CCHF and die on January 3 – have tested positive for high viral load.

Speaking to TOI, director of Pune’s National Institute of Virology Dr A C Mishra said, "20% of the samples from six villages show positive CCHF infection. This means the virus has been circulating for some time in India and has just recently been detected."

Mishra added, "We are therefore setting up a diagnostic laboratory in Ahmedabad to test human samples for CCHF. At present, by the time the samples reach NIV, we lose a day. Three experts from Gujarat are being trained at NIV on safe handling of the human samples and how to interpret the results. Quick diagnosis is crucial with this virus. It kills most infected humans."

NIV has also picked up samples from rodents to check for the virus. "We have to immediately cut transmission of the virus from ticks to cattle by intensifying operation pesticide, cleaning the cattle and their sheds. If even 50% of the ticks are destroyed from the body of the host, the transmission can be halted," Mishra added.

So does this mean the cattle infected have to be culled just like chicken were during the bird flu outbreak in India? No, said Mishra. "Once the H5N1 virus infected poultry or birds, it killed them. That’s how we knew where to look for the virus and killed all poultry around the site to stop transmission. In case of CCHF, the virus sits inside an animal’s body but does not harm it. So we can’t collect samples from all animals in Gujarat looking for the virus. Culling is, therefore, not recommended. We have to just break the cycle of the virus jumping from ticks to cattle," he added.

TOI had first reported how NIV last week found that a particular variety of ticks, Hyalomma, were carrying high quantities of CCHF virus in Ahmedabad, proving that the virus wasn’t imported.

"Our main recommendation, therefore, is to reduce tick population which can circulate the virus in the environment for many years. They lay their eggs and transfer the virus into it. The egg hatches and continues to infect animals," Mishra added. The CCHF virus is noted by the Union health ministry as a bio-safety level IV agent – of maximum danger.

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