A new study reveals that worm infection might be one of the major risk factors for individuals with latent tuberculosis infection to develop the active disease.
The study was carried out in individuals with latent TB co-infected with intestinal worms (Strongyloides stercoralis). Commonly called the threadworm and found largely in tropical and subtropical countries, it affects about 50 to 100 million people worldwide.
Three groups of 44 individuals each were selected for the study. Individuals in the first group had latent TB and worm co-infection, those in the second had latent TB but no worm infection and the third set had only worm infection.
The blood samples of the patients with latent TB and worm co-infection showed decreased levels of human TB antibodies (IgG and IgM) compared with those of people with latent TB. Also, there was a decrease in B cells (a type of white blood immunity cells, guardian cells) and their activating factors. The diminished levels of the TB antibodies could potentially have detrimental effects on immune response to TB.
De-worming treatment
The patients with worms were administered anti-parasitic tablets — Ivermectin and Albendazole.
Six months later, their blood and stool samples were collected and studied.
The results showed that post treatment, there was a significant increase in the levels of TB antibodies. The B cell numbers and their responses significantly increased following treatment. The results were recently published in the PLOS Neglected Tropical Diseases.
The exact cause of antibody increase is not yet fully understood; but the study was able to provide an evidence of a significant association of worm infection with modulation of B cell function. “Treatment with a single dose of anti-worm tablets could be used prior to new TB vaccine trials, as the response will be much better,” says Dr. Subash Babu of National Institute of Research in Tuberculosis (NIRT), Chennai, and senior author of the paper.
The individuals with latent TB and worm co-infection are more susceptible to active TB, as their immunity is reduced. “We are planning to conduct further studies to understand the pathway by which the worms alter these antibodies and the immune responses,” says Dr. R. Anuradha, Post-doctoral fellow at National Institute of Research in TB, Chennai, and first author of the paper. This study also suggests a better treatment path to be used in countries endemic to both TB and worm infection.
