Chennai: Researchers at Tamil Nadu’s National Institute for Research in Tuberculosis (NIRT) have sought funding from the US National Institutes of Health to conduct a domestic screening of domestic animals in Chennai, as they are exposed to human-to-animal transmission of tuberculosis (TB). Examples have been found.
Dr. P. Kannan, Scientist D, NIRT, which comes under the Indian Council of Medical Research (ICMR), told ThePrint: “We screened about 162 cattle in four farms around Chennai and 20 of them had tuberculosis. had got. Handler was also positive. This is the first instance where we have found evidence of reverse zoonosis of TB.
Examples of zoonosis – transmission of a disease from animal to human – TB bacteria have been found in the United Kingdom, but not in India. But now, the detection of TB in farm animals in India, which have contracted the disease from their handlers, has raised fears that the human-to-animal barrier to transmission has been breached.
“In a farm setup, the protocol is to isolate the animals as cow slaughter is not allowed. Now that we have evidence of reverse zoonosis, there is also concern about transmission from animals to humans. So we are planning home screening to understand its prevalence,” said Kannan. “To control human tuberculosis, we need to control animal tuberculosis.”
During the study on farm animals from 2015 to 2019, the animals were screened for TB using the Mantoux test. During the study, six animals died of the disease and autopsy revealed TB lesions on lungs, liver, spleen, udder etc. The findings were published in the journal. Nature,
Kannan’s team too detected Mycobacterium origis, a member of the TB pantheon, in two blackbucks and a spotted deer in Guindy National Park, Tamil Nadu.
The NIRT researchers pointed out the need to keep the environment in mind in such cases.
“Nevertheless, it would be wise to take into account the environment where a high potential for transmission exists due to increased human-animal contact. Since it is well known that the pathogen is capable of causing infection in both human and animal hosts, from a health standpoint Successful implementation requires systematic monitoring and screening of spotted deer, blackbuck as well as nearby humans. Cross-border and emerging diseases,
Dr Uma Devi, Head of the Department of Immunology at NIRT, said that evidence of TB zoonoses was found many years ago in the UK. “Mycobacterium bovis was transmitted from animals to humans, but no cases were found in India. But these latest findings in farm animals are important and additional research is needed,” she said.
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Recommendation for BCG vaccination
India made BCG vaccination, which prevents TB, mandatory decades ago and still struggles with the world highest burden In case of illness, NIRT has sent a recommendation to the government for BCG booster shots to household contacts of positive patients.
“We are studying the effect of BCG vaccination in children aged 6 to 12 years. We will follow them for three years and see if they catch the disease. Children catch the disease in middle school,” said NIRT director Dr Padmapriyadarshini C.
“We have also had two meetings with our government on the proposal to remove domestic contacts (of patients). For testing, we plan to study 8,000 children.”
The trial has already been registered with the Clinical Trials Registry of India. study summary Reads: “The Bacille Calmette Guerin (BCG) vaccine is one of the most commonly used vaccines in the world to reduce the risk of natural tuberculosis infection. The efficacy of BCG vaccination in newborns is well known and has been linked to meningitis and meningitis in children.” Has protective effect against disseminated TB.
“However, there is considerable uncertainty over BCG repatriation. It is known that BCG vaccination enhances the immune response, but it is not yet established whether BCG vaccination can help prevent TB disease in household contacts.
The primary objective of this study, the summary states, “is to assess the efficacy of BCG revaccination compared to oral chemoprophylaxis in preventing TB disease in household contacts aged 6–18 years”.
(Edited by Nida Fatima Siddiqui)