# Sero‐Prevalence and Molecular Detection of Mycobacterium bovis in Cattle at Sylhet Division of Bangladesh

## TL;DR

This study finds a 10.6% prevalence of bovine tuberculosis in cattle in Bangladesh, with higher rates in milk samples and specific risk groups.

## Contribution

The study provides new serological and molecular prevalence data for M. bovis in dairy cattle in Bangladesh.

## Key findings

- M. bovis prevalence was 10.6% overall, with higher rates in milk (14.8%) than blood (6.4%).
- Diarrheic animals showed the highest prevalence (19.49%), followed by females and Holstein Friesian cows.
- PCR confirmed the presence of M. bovis, indicating the endemic nature of bTB in the region.

## Abstract

Mycobacterium bovis, the cause of bovine tuberculosis (bTB), is a contagious, notifiable, chronic bacterial disease that causes economic losses. bTB remains a significant zoonotic threat, particularly in resource‐limited settings where reliable prevalence data are still lacking.

This study aimed to determine the serological prevalence and molecular detection of bTB from different commercial and individual dairy farms of Sylhet and Sunamganj districts in Bangladesh.

A cross‐sectional study was conducted on a total of 250 blood and 250 milk samples, which were collected across selected dairy farms. Serological testing was performed using indirect ELISA, and molecular detection of M. bovis was carried out through PCR. Associations between infection status and potential risk factors were evaluated using chi‐square tests and logistic regression models.

The overall prevalence of M. bovis was 10.6%. Molecular detection through PCR revealed a higher prevalence in milk (14.8%) compared to blood (6.4%) samples. Serological testing showed that the prevalence in Sylhet district was lower (5.3%) than in Sunamganj district (12.0%). The highest prevalence was observed in diarrhoeic animals (19.49%), followed by female cattle (13.58%) and Holstein Friesian cows (14.0%). Cattle aged 1–3 years showed a notable prevalence of 17.51%.

The presence of M. bovis in dairy cattle herds was confirmed by both molecular and serological methods, highlighting the endemic nature of bTB in the study area. These findings underscore the importance of routine surveillance, combining diagnostic approaches and implementing effective control measures to reduce the burden of bTB in dairy production systems.

Five hundred samples (250 milk and 250 blood samples) were collected by using a simple random sampling method. Following collection, blood was let to clot by being left undisturbed at room temperature for 15–30 min, and serum was separated by centrifugation. Extraction of DNA from milk and blood was performed accordingly. PCR was conducted using the target primer sequences and identified by electrophoresis by visualizing the M. bovis–specific band at 150 base pairs.