Contact tracing/pre-employment screening for pulmonary tuberculosis: should positive Mantoux test necessitates...

Pulmonary tuberculosis (PTB) remains a scourge in most developing countries. Mantoux skin test and more commonly chest radiography are some of the methods of diagnosing the disease, especially with regard to contact tracing and pre-employment screening. Regular use of radiography has both safety and cost implications. This study aimed at establishing if any justification exists in requesting for chest radiographs in asymptomatic subjects with a positive Mantoux skin test reaction.

174 adults comprising PTB contacts and newly employed/admitted university staff/students were recruited into the study. They were 89 males (51.1%) and 85 females (48.9%). All subjects had Mantoux test (using purified protein derivative, PPD). Patients who had positive Mantoux reaction subsequently were subjected to posteroanterior chest radiographic examination. Mantoux test and chest radiographic findings were then correlated with each other.

102 subjects (59.2%) had positive Mantoux reactions, while 27 subjects (31.1%) had abnormal chest radiographs. There was no significant correlation between Mantoux readings and chest radiographic findings (P=0.106).

It is concluded that other ancillary tests like sputum examination and/or, where available, Interferon and ESAT tests should be carried out before chest radiograph is requested in subjects with positive Mantoux reaction.