Screening pulmonary tuberculosis suspects in Malawi: testing different strategies.

Alternative strategies for screening tuberculosis (TB) suspects are needed in sub-saharan Africa. Ambulatory adult TB suspects who were seen in the chronic cough room of Queen Elizabeth Central Hospital, Blantyre, Malawi, were assessed with respect to appropriateness of referral. Appropriate referrals (patients with cough 3 weeks or longer, weight loss and no antibiotic response) were screened by 3 sputum specimens for microscopy and culture of Mycobacterium tuberculosis and chest radiography (CXR). Hypothetical strategy A (screening by sputum smear examination followed by CXR in patients with negative sputum smears) was compared with strategy B (screening by CXR followed by sputum smear examination in patients with a CXR consistent with TB) in terms of diagnostic efficacy and cost. Of 1127 patients referred to the cough room, 402 (38%) were appropriate TB suspect referrals. Of these, 111 (28%) were sputum smear-positive, 213 (53%) were culture-positive, and 221 (55%) had smear and/or culture-positive evidence of TB. Routine CXR was consistent with pulmonary (P) TB in 230 patients (57%). With strategy A, 243 (60%) patients were diagnosed as PTB, but 40 (25%) of those not diagnosed as PTB had positive mycobacterial cultures. With strategy B, 230 patients (57%) were diagnosed as PTB, but 53 (31%) of those not diagnosed as PTB had positive mycobacterial cultures, including 13 with smear-positive sputum. The cost per diagnosed case of PTB was US$ 4.63 with strategy A and US$ 5.44 with strategy B. Screening patients with good criteria of TB has high diagnostic sensitivity, but screening by CXR is less effective and more costly than screening by sputum smear microscopy.

Tuberculous lymphadenitis, a diagnostic problem in areas of high prevalence of HIV and tuberculosis.

The human immunodeficiency virus (HIV) epidemic is associated with a marked increase of tuberculosis cases. The influence of HIV on diagnostic methods for tuberculous lymphadenitis is less clear. In an environment of high HIV and tuberculosis prevalence in Blantyre, Malawi, a prospective study compared results of basic procedures diagnosing tuberculous lymphadenitis with the outcome of histology and/or culture. One hundred out-patients, aged 15-55 years, with extra-inguinal lymphadenopathy not responding to general antibiotics, entered the study. Among 52 cases, with whom all procedures were carried out in accordance with the protocol, 38 (73%) were diagnosed as tuberculous lymphadenitis; 84% of the latter (32/38) were seropositive for HIV. Needle aspirate and biopsy smears stained by the Ziehl-Neelsen technique contributed little to detecting tuberculosis, 8% and 11% respectively. In contrast, macroscopic caseation of excised lymph nodes showed a high yield of 82%, which was similar to histology, and higher than that of Löwenstein-Jensen culture (61%). The study suggested that HIV positivity of tuberculous lymphadenitis patients decreased the possibility of histology and culture both being indicative of tuberculosis (odds ratio 0.10; P = 0.06). Consequently histology results, often used as the single definitive method, failed to diagnose 18% (7/38) of tuberculosis cases. However, it was reassuring that 4 simple methods, which can safely be carried out at district level, could be expected to diagnose 80-95% of tuberculous lymphadenitis cases in a timely and cost-effective manner.

PIP: A prospective study conducted in 1994-95 in Blantyre, Malawi, investigated the influence of HIV on diagnostic methods for tuberculous lymphadenitis in 100 outpatients 15-55 years old with extra-inguinal lymphadenopathy not responsive to general antibiotics. For the 52 cases for which all diagnostic procedures were carried out, 38 (73%) were diagnosed as tuberculous lymphadenitis; 32 (84%) of these patients were HIV-positive. Needle aspirate and biopsy smears stained by the Ziehl-Neelsen technique contributed only 8% and 11%, respectively, to detecting tuberculosis. In contrast, macroscopic caseation of excised lymph nodes, histology, and Lowenstein-Jensen culture had yields of 82%, 82%, and 61%, respectively. These findings indicate that, in tuberculous lymphadenitis patients, HIV infection decreases the diagnostic power of culture and histology. However, use of the other methods can diagnose 80-95% of tuberculous lymphadenitis cases in a cost-effective manner in areas with high prevalences of both HIV and tuberculosis.

Delays in diagnosis and treatment of smear-positive tuberculosis and the incidence of tuberculosis in hospital nurses in Blantyre, Malawi.

There is little information about nosocomial transmission of tuberculosis (TB) in sub-Saharan Africa. A study was carried out to examine the process of diagnosis and treatment of smear-positive pulmonary TB patients in Queen Elizabeth Central Hospital, Blantyre, Malawi, and the incidence of TB in nurses working in specific departments of the hospital. Case notes of 1365 patients with smear-positive pulmonary TB, diagnosed and treated at the hospital in 1993 and 1994, were analysed. The number of qualified nurses who worked in specific departments of the hospital between 1993 and 1994 and the number who were diagnosed and treated for TB during this period were obtained from nursing records. 787 patients (58%) were diagnosed as out-patients and 578 (42%) were diagnosed in hospital wards, 544 from medical wards. In medical wards, there were long delays from the time of admission to diagnosis and start of anti-TB treatment in new and previously treated TB patients. Of 310 qualified nurses, 12 (4%) were treated for TB in 1993-1994; 4 (14%) of 29 nurses working in the medical wards developed TB. The results indicate the importance of finding simple measures in resource-poor countries to improve the diagnosis and treatment of TB in hospital patients in order to decrease the risk of nosocomial TB transmission.

Case finding for pulmonary tuberculosis, Queen Elizabeth Central Hospital, Blantyre, Malawi.

SETTING: Queen Elizabeth Central Hospital, Malawi. OBJECTIVE: To evaluate the investigation of patients with cough who attend out-patient services and the adherence to recommended diagnostic protocols. DESIGN: Two operational studies in 1995: 1) an audit of management of patients presenting to non-fee-paying out-patient services (OPD) with cough, and 2) an audit of the laboratory sputum register and the OPD cough register. The annual number of out-patient attendances was also recorded. RESULTS: Of 2381 patients seen by OPD medical assistants, 438 (18.4%) complained of cough: 303 for < 3 weeks and 135 for > or = 3 weeks. Sputum smear examinations were requested in 97 patients, 79 (58.5%) with long duration and 18 (5.9%) with short duration of cough. Between May and December 1995, of the 1668 OPD patients who had sputum results in the laboratory register, 1392 (83%) had sputum results in the cough register. Of patients listed in the cough register, 98% collected their sputum smear results. In 1995, there were 395,439 OPD attendances; data extrapolation suggests that about 15,000 patients should have had sputum examined instead of the 2337 listed in the laboratory register. CONCLUSION: A large burden is imposed on out-patient services by patients with cough. Despite recommended protocols, this investigation suggests deficiencies in case detection which require further study.