Cattle TB can hinder fight against human TB, scientists say

Medical students generally know that tuberculosis in cattle can be passed on to humans.

Nurul Islam Hasibfrom Cape Town, South Africabdnews24.com
Published : 4 Dec 2015, 03:29 PM
Updated : 5 Dec 2015, 12:39 PM

But the ongoing 46th Union World Conference on Lung Health in Cape Town has learnt that this can frustrate ongoing efforts to end human TB by 2030.

Scientists flagged this bovine strain of TB after a study found high rates of zoonotic TB among Nigerian cattle and livestock workers.

Dr Francisco Olea-Popelka, Assistant Professor at the College of Veterinary Medicine and Biomedical Sciences at Colorado State University, said zoonotic TB had been unreported for the last two to three decades in the world.

“The people who we're now identifying (affected by zoonotic TB) likely represent the tip of the iceberg,” he said at a press briefing, on the sidelines.

Available evidence suggests 1.4 percent of all TB cases are caused by zoonotic strains.

This would represent approximately 126,000 people affected by zoonotic TB worldwide annually, or over 1 million cases in the last decade, Dr Olea-Popelka said.

Replying to a question, he said he had found scientific papers indicating that this TB was also present in Bangladesh.

Indian studies presented in the conference separately indicated that elephants also get the TB which is more dangerous as it is similar to the human strains of TB, mycobacterium, which is air-borne.

But the cattle TB comes from drinking unpasteurized milk and eating raw meat.

Neglect leads risks

Dr Olea-Popelka said the major challenge of tackling zoonotic TB was that most of the countries do not specify which bacterium caused the TB when they start treatment for the disease.

“This neglect has led patients to receive improper diagnosis and inadequate treatment, especially in developing regions,” he said.

Mycobacterium bovis, the cattle strain, is naturally resistant to pyrazinamide, a key first-line medicine used in the standard TB treatment regimen.

Using pyrazinamide to treat patients with bovine TB increases the risks of treatment failure and developing resistance to other TB medicines used in course of treatment, he said.

In zoonotic TB, patients must take drugs for nine months; compared to the standard six-month TB treatment, the doctor said.

Globally it is recommended not to treat TB infected cattle as it can spread the bacterium further. Developed countries kill such cattle.

Scientists say broader policies must be taken as those affected by bovine TB came from the most neglected areas in remote places.