Descriptive study of human and bovine tuberculosis in Querétaro, México

A 5-year retrospective study (1992-1996) to look at the situation of human tuberculosis was conducted in Querétaro, México. Also, a 6-month study to determine the frequency of gross lesions in dairy cattle at slaughter, and a short experiment to evaluate the effect of sodium borate in the survival of M. bovis in lesions were carried out. The number of cases were 114 in 1992, 211 in 1995, and 174 in 1996. Possible risk factors were: overcrowding, under-nutrition, previous cases of TB in the family, concurrent Diabetes mellitus, poor personal hygiene, smoking, and alcohol abuse. Eighty percent of the cases were pulmonary. The number of cases increase with age, from 5% in patients 10-year old or younger to 42% in patients 50-year old or older. Seventy-two percent were cured, and only 6% die. Persistent coughing was by far the most observed clinical symptom. From 112 acid-fast negative samples, 8.9% were positive by culture. From 1,201 carcasses revised at slaughter, 17% presented TB-gross lesions. Ninety-six percent were localized lesions involving frequently a single organ, mostly retropharyngeal, mediastinal, mesenteric and mandibular lymph. From 102 lesions, 95% were TB-compatible, and 79% were positive to isolation of M. bovis. Most affected animals were female > 2 years old. It was observed that keeping lesions in a 6% sodium borate solution does not affect the diagnosis of M. bovis by culture after 150 days.