Isolation and Molecular Characterization of Mycobacterium tuberculosis from Humans and Cattle in Namwala District, Zambia

Abstract

Mycobacterium tuberculosis, the causative agent of tuberculosis in humans, is considered primarily a human pathogen. It has, however, been reported in a wide range of domestic and wild animals, often living in close prolonged contact with humans. Sputum samples in which acid fast bacteria were detected in smears were collected from patients at three health facilities in Namwala district, Zambia. Samples from cattle presenting gross lesions compatible with bovine tuberculosis were collected at a local abattoir in the same district. Isolated mycobacteria were identified and genotyped using classical molecular methods. From a total of 33 isolates of M. tuberculosis detected (30 from humans and 3 from cattle), two cattle isolates shared the same spoligotype and MIRU-VNTR pattern with a human patient. This study has for the first time documented the isolation of M. tuberculosis from cattle in Zambia and provides molecular evidence of an epidemiological link between M. tuberculosis isolates from humans and cattle in Namwala district. A possible spill back of M. tuberculosis to humans cannot be excluded and therefore further studies documenting to what extent M. tuberculosis is shed in cattle milk are needed. This finding further suggests that veterinary public health measures to control human TB, should also take into account the bovine reservoir.

Updated Reference Genome Sequence and Annotation of Mycobacterium bovis AF2122/97

“…bTB exacts a tremendous global economic toll through productivity losses and disease control costs, while zoonotic transmission of M. bovis infection is a threat to human health (1–6). …”

Non-Tuberculous Mycobacteria Recovered from Suspected TB Cases in Namwala District of Zambia

“…This study observed that NTM was mostly recovered from suspected TB cases whose occupation was farming. This could possibly due to overtime exposure to NTM contaminated soil and water as agriculture is the main economic activity in Namwala district (Malama et al, 2014c).In the present study NTM from humans in Namwala district were isolated and sequenced. This observation was also made in a study done in Shanghai China by Wu et al (2014).…”

“…Four sampling areas were selected and these are; Namwala central, Maala, Kabulamwanda and Chitongo. Namwala is one of the districts in Zambia with the highest TB prevalence in both animals and humans (Malama et al, 2014c;Munyeme et al, 2009). It covers an estimated total area of about 10,000 square kilometers and lies between latitudes 15 and 17°S of the equator and longitude 25 and 27°E.…”

“…This offer nutritive varieties of rich lush green grass for both cattle and wildlife for a greater part of the year than the surrounding Savannah woodlands (Munyeme et al, 2010). Namwala district supports approximately 30 000 herds of cattle and approximately 44,000 Kafue lechwe (Malama et al, 2014c) and agriculture is the main economic activity. Humans and animals commonly share the same micro environments such as water drinking points, especially in dry seasons (Phiri, 2006), increasing the possibility of interspecies disease transmission or contamination of water sources, which could potentially lead to a zoonotic transmission to humans (Katale et al, 2014).…”

Isolation of Mycobacterium tuberculosis from Antelope cervicapra and Gazelle bennettii in India and confirmation by molecular tests

“…An important emerging concern is not whether infection of wildlife species with MT is novel, but recent observations that MT isolates recovered from humans and members belonging to Bovidae from the same geographical area share identical spoligotypes and VNTR-MIRU profiles (Malama et al 2014;Romero et al 2011). The evidence of molecular epidemiological link provided above, has been suggested as a possible mechanism for spill backs or spill overs of MT from human TB to cattle (Malama et al 2014;Romero et al 2011;Michel et al 2013). The TB infection due to MT in antelope and gazelle identified in the present study may have been due to a number of unique situations coexisting in the sanctuary.…”