Human bovine tuberculosis – remains in the differential

Abstract

Mycobacterium bovis is a pathogen of cattle. The unpasteurized milk of affected cattle is a source of infection in humans. Despite the screening of cattle and the pasteurization of milk, M bovis has not been eradicated. A high index of clinical suspicion is needed in symptomatic patients with a history of possible exposure. At risk groups include animal workers, farmers, meat packers, vets and zoo keepers. Humans are usually infected by the aerosol route. We present two cases of human bovine tuberculosis. One was a presumptive case and the second was a confirmed case. Both responded well to antituberculous therapy. In the confirmed case, there was evidence of transmission to the partner living in the same house. Rifampicin prophylaxis was given to the exposed case. The M. bovis from the confirmed case was isoniazid resistant, in addition to having the well known resistance to pyrazinamide. Isoniazid resistance has been described before in those who are immunocompromised. We describe it in an immunocompetent patient. Case reports Case 1A 50-year-old male farm worker presented to our clinic in July 2008 with a history of tightness of the chest, dyspnoea and erythema nodosum in March of the same year. His antistreptolysin O titre was elevated at that time at 545 IU ml 21. There was no history of night sweats, weight loss, cough or constitutional symptoms. In the family history, his sister had erythema nodosum during her pregnancy. He was a welder by occupation. His past medical history included childhood asthma and allergic rhinitis. On examination, his temperature was 36.5uC, his blood pressure 125/73 mmHg, pulse 66 beats min 21 and oxygen saturation was 96 % on ambient air. His cardiovascular system was normal, a respiratory examination was unremarkable and his abdomen was soft and non-tender. There was no cervical and axillary lymph node enlargement. Leg examination revealed red healing macules on the anterior aspect of both shins associated with some dry skin and scaling. There was no pitting oedema.Laboratory examination showed a normal full blood count with an erythrocyte sedimentation rate of 15 mm h A chest X-ray showed a prominent right hilum. A computed tomography (CT) scan of the thorax showed enlargement of the mediastinal lymph nodes along with nodular and linear opacification in the right upper lobe (Fig. 1).The standard Mantoux test, consisting of 2 tuberculin units Statens Serum Institute tuberculin RT23 in 0.1 ml solution injected intradermally, was strongly positive at 4 cm. Bronchoscopy results were normal. Direct microscopy with Ziehl-Neelsen staining and tuberculosis (TB) culture on sputum and bronchial washings were negative on two occasions. In view of a history of exposure to bovine TB (bTB) in the past, a presumptive diagnosis of bTB was made. The patient was commenced on antituberculous therapy (ATT). He was treated with isoniazid, rifampicin and ethambutol for 2 months, followed by isoniazid and rifampicin for a further 7 months. After 9 months of treatment the patient was asymptomatic. T...

The Prevalence of Tuberculosis in Cattle and Their Handlers in North Tongu, Volta Region, Ghana.

“…Although the fulanis usually treat their animals with antimicrobial to reduce the level of infection in the herd, this was not effective probably because the antimicrobials employed were not effective against M. bovis which further confirmed that mycobacterium bovis is resistant to many antibiotics (Bilal et al, 2010).…”

“…Since people who attend to these animals such as herdsmen and veterinarians as well as the general public who consume fresh milk or infected meat are exposed to bovine TB from cattle (Bilal et al, 2010). There is therefore the need to ascertain the burden of BTB in cattle and in human in Ghana using the field approach, rather than abattoir and hospital based approaches targeting herdsmen in rural settings.…”

Prevalence and herd-level risk factors of bovine tuberculosis in the State of Goiás, Brazil

“…It is caused by Mycobacterium bovis (M. bovis) and is one of the endemic diseases that generate major challenges to government authorities, medical and veterinary professionals, as well as agribusiness value-chains (SKUCE et al, 2012;OIE, 2015). Bovine tuberculosis poses a threat to public health, especially through human consumption of milk and dairy products, as well as by exposure to the aerosols of infected animals (BILAL et al, 2010).…”

Occurrence of bovine tuberculosis among cattle herds from nomadic peri-urban settlements and cattle slaughtered at the municipal abattoir of Bauchi, North-Eastern Nigeria

“…In humans, infection with bTB occurs through ingestion or inhalation of contaminated milk and milk products, contaminated meat and meat products and infected aerosols (Bilal et al, 2010;Danbirni et al, 2017). Studies have shown that a large proportion of humans (82%) and cattle (85%) population in African countries live in agric-economic zones where bTB is endemic or inadequately controlled (Ayele et al, 2004).…”