Tuberculin sensitivity and HIV-1 status of patients attending a sexually transmitted diseases clinic in Lusaka, Zambia: a cross-sectional study

A cross-sectional study of the Mantoux response and HIV-1 status of a sample of patients with sexually transmitted diseases and skin diseases in Lusaka Zambia sought to estimate the prevalence of latent tuberculous infection. The sample was selected from patients attending the sexually transmitted diseases/dermatology section at the University Teaching Hospital Lusaka Zambia between July and September 1990. A questionnaire regarding socioeconomic factors history of TB contact with TB location and documentation of bacillus Calmette-Guerin (BCG) scar(s) and history of BCG vaccination was completed and a physical examination for acquired immune deficiency syndrome (AIDS) was carried out. The Mantoux result was recorded as the average diameter of induration measured in 2 perpendicular directions by the pen and palpation method. A total of 158 patients (59%) were HIV-1 positive. Of the 66 women who took part 46 (70%) were HIV-1 positive; of the 201 men 112 (56%) were HIV-1 positive (p = 0.06). 232 patients had sexually transmitted diseases the commonest being genital ulceration; 123/231 (53%) were HIV-1 positive. The remaining 36 patients had skin diseases the commonest being herpes zoster; 32/36 (89%) were HIV-1 positive. Of the 267 patients remaining in the study 193 (72%) returned to have their Mantoux test read 188 within 48-72 h. 106 (67%) HIV-1 positive patients and 82 (75%) HIV-1 negative patients returned. Of the 82 HIV-1 negative patients 51 (62%) had a Mantoux reaction >or= 10 mm; 55 (67%) had a reaction >or= 5 mm. Of the 106 HIV-1 positive patients only 32 (30%) had a Mantoux reaction >or= 10 mm; 35 (33%) had a response >or= 5 mm. Comparing HIV-1 negative and HIV-1 positive participants gave a significant odds ratio of 3.85 for a Mantoux response >or= 10 mm. Among the individuals with a Mantoux reaction >or= 10 mm 9/32 (28%) of HIV-1 positive participants had a megareaction >or= 30 mm while megareactions occurred in 4/51 (8%) of HIV-1 negative participants (odds ratio 4.6).