Calcutta, June 9: Why are patients — with more and more children among them — in the city getting infected with HIV through blood transfusion, despite the existence of international and national protocols on blood safety?

The blame, according to medical experts, lies with the government and its inability to implement these protocols, that need to be followed to the last letter.

The primary problem is the absence of screening the blood donors who attend camps in and around the city, leading to “bad blood” entering the banks. The number of voluntary donation camps has risen from 200 to 500 per month in Calcutta over the past 10 years, but proper donor-screening is not being done.

“In fact, many organisers and clubs are luring all types of donors with gifts,” observes D. Ashis, secretary of Medical Bank.

Adds consultant haematologist R.N. Dutta: “Donor-screening is extremely important and the government must ensure that even a single person who has been exposed to risky behaviour (like multiple sex partners or drug abuse) is eliminated from the donor pool.”

The government is also in no position to provide modified and more accurate testing methods to detect HIV. The present techniques, be it the ELISA reader method or rapid test, are not efficient enough to pick up the antibodies in the initial stage of a person’s infection.

The modified P24 antigen method, used in the West, is not being used here because of the cost factor. Each test by this method costs around Rs 1,500, while the ELISA test costs Rs 35, and the rapid test Rs 55. But these tests do not eliminate the threat from the window period.

“The window period is a time of between four and six weeks after a person is infected during which the viral load is so low that the test will not show HIV antibody positive,” explains D.K. Neogi, head of the virology department at the School of Tropical Medicine.

Technology aside, negligence at any stage of blood collection, testing and storage, along with an absence of donor-screening, are the main reasons for an HIV infection through transfusion.

“I have come across some cases where the source of the contaminated blood could not be traced. So how can one say that window period is responsible?” demanded Dutta.

Director of health services Prabhakar Chatterjee said discussions with experts were on for more improved techniques of testing to reduce the window period. “We have instructed all blood banks to double and triple-check every blood unit with existing methods before passing it on for transfusion,” he added.