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Trapping the killer

Scientists at the Indian Institute 01 Chemical Biology OICB), Calcutt are grappling wil , killer: Laishmania Donovani. It is protozoa that derives its name from its discoverers, Laishman an Donovani who discovered the pathogen at the turn of the centu !I soon after Ronald Ross isolated the malaria parasite. Just as the malan parasite thrives Donovani finds its host in sand-fli infesting the warn of eastern India. The sand-fly ij especially rampant in Bihar where it breeds in dark, damp cowsheds. A4 a result, recurrent outbreaks of kalJ azar have killed thousands in Siha since the return decades back.

A carrier flea releases Donovanj into the human blood stream every time it stings. And thi pathogen swiftly navigates its way to the liver and spleen, attackind the organs' tissues. This causes a nagging fever, depletion of whit4 blood corpuscles, swelling of the belly, and then death - if the dis4 ease is not diagnosed in time.

The lIC8 has created a pathoger! bank with nearly 20 clinical isolates of L Donovani preserved in cryo4 genic (-700C) conditions, to be occasionally retrieved, implanted into laboratory animals, and put back to hibernation. The protozoa'4 enzyme profile has already been charted and their DNA mappinq would commence soon. Normally, blood tests do not reveal thqq pathogen, as its presence in the blood stream is negligible. Thi I makes tissue culture from the liver and spleen - the nesting planes of the protozoa - necessary.

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