Pulmonary Tuberculosis in Southeastern Nigeria

the incidence of pulmonary tuberculosis in Southeastern Nigeria was studied using cultures and microscopic examination of sputa. The isolation of acid-fast bacilli (AFB) from sputa of some inand out-patients in hospitals and health centers revealed the presence of Mycobacterium tuberculosis in 420 (31.7%) out of the 1,324 patients examined during a TB outbreak. A mortality rate of 9 (2.14%) of the 420 AFB-positive cases was observed during the study period of 10 months. The most affected age group was between 16 and 35 years, with high incidence rates found in traders (33.8%), health workers (31.0%), and food vendors (13.8%). Male subjects had a higher incidence of 35.6%, compared to 26.9% in females. Intensification of training programs for adequate numbers of medical diagnostic personnel in referral hospitals; public health education and integration of socio-political, cultural and economic frameworks are advocated in the subregion to avert an eminent TB in Southeastern Nigeria. SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH 318 Vol 36 No. 2 March 2005 disease in developing countries where 95% of all TB cases occur, TB accounts for 25% of all avoidable deaths. It is sadly true that 75% of TB cases in developing countries involve adults in the most productive age group, 15-50 years (Mahler et al, 1997; Ruck, 1997). Several countries with known TB endemicity have been identified in Asia and sub-Saharan Africa with the largest estimated numbers of new cases in the African subregion occurring in Nigeria, followed by Zaire, as reported by Kochi (1997). Kaufmann and Van-Embden (1993) observed that the declining incidence in developed countries has reversed in the past few years. For instance, an 18% increase in incidence was reported in the USA between 1988 and 1992, while increases in the European countries at during the same period ranged between 4% in the United Kingdom and 33% in Switzerland. Kaufmann and Van-Embden (1993) and Mahler et al, (1997) reported that the morbidity and mortality profiles of TB are increasing worldwide as the emerging trend of the global HIV/AIDS pandemic is casting a gloomy prospect on TB containment programs. It is estimated that more than 16 million people are infected with HIV globally, and about six million are concomitantly infected with TB (Kaufmann and Van-Embden, 1993; Mahler et al, 1997; Utsalo et al, 1998). Subsaharan Africa accounts for 70% of this HIV/AIDS/ TB co-infection burden, while Asia accounts for 20% (Mahler et al, 1997). Utsalo et al (1998) reported that HIV is the most powerful factor known to increase the risk of progression of infection in the host to disease. These views are shared by Murray et al (1990), who earlier reported that the HIV/AIDS pandemic is largely instrumental in the resurgence of TB in parts of the world with effective TB control programs and the escalation of the already precarious situations in developing countries like Nigeria. This paper examines the incidence rate of PTB in Southeastern Nigeria after the DOTS laboratory techniques were introduced, and follows an outbreak in the study area in March, 2001. MATERIALS AND METHODS Sources and collection of samples Sputa were collected from in(hospitalized cases) and out(non-hospitalized cases) patients with cough in 16 hospitals (including health centers) in Southeastern Nigeria ( Akwa Ibom and Cross River States). The survey lasted for 10 months, March through December, 2001 following an outbreak in the subregion in March, 2001. Samples were aseptically collected in sterile bottles and processed for analysis within 3 hours of collection. Samples were collected at the following referral hospitals and health centers representing various communities: University of Uyo Health Center (UUHC); Infections Disease Hospital (IDHE); Iquita General Hospital, Oron (IGHO); Mercy Hospital, Abak (MHA); General Hospital, Urua Akpan (GHUA) in Essien Udim; General Hospital, Ikono (GHIK); Mary Slessor Hospital, Itu (MSHI); Leprosy Hospital, Ekpene Obom (LHEO) in Etinan; University of Uyo Teaching Hospital (UUTH) and General Hospital, Ikot Abasi (GHIA), all in Akwa Ibom State. The referral hospitals in Cross River State were the University of Calabar Teaching Hospital (UCTH), General Hospital, Calabar (GHC), General Hospital, Ikom (GHIM) and General Hospital, Obubra (GHO). Processing of samples for microscopic examination Each sputum was concentrated by decontaminating with an equal volume of 4% NaOH and homogenized by shaking for 15 minutes with a wrist-action shaker as earlier described (Idigbe and Onwujekwe, 1983). The homogenates were centrifuged at 4,000 rpm for 15 minutes. The supernatants were decanted and the deposit washed with sterile distilled water and recentrifuged as before. The final deposits and the unprocessed portion were then examined separately by microscopy and culture. The ZiehlNeelsen’s (ZN) staining technique was adopted (Cruickshank et al, 1975; Baker et al, 1998; Prescott et al, 2002) using methylene blue as a counterstain for the identification of acid-fast bacilli (AFB). This is the technique recommended for the DOTS program, with greater than 80% success. Sputum culture and identification A loopful of each sputum sample was aseptically inoculated into the solidified Lowenstein Jensen Glycerol Egg medium using a platinum wire loop and the cultures were incubated at 37oC aerobically for 6-8 weeks. The culture bottles were examined weekly for growth exPULMONARY TUBERCULOSIS IN SOUTHEASTERN NIGERIA Vol 36 No. 2 March 2005 319 pected to appear after 2 weeks of primary incubation. Results were regarded as negative if no colonies appeared after 8 weeks as earlier reported (Idigbe and Onwujekwe, 1983). All the isolates were characterized and identified by microscopic examination, colonial morphology and biochemical tests, which included Gram reaction, catalase, presence or absence of endospore and sugar fermentation profile (Cowan, 1985; Holt et al, 1994). The results were recorded as AFB (+) to AFB (++++) for the positive cases, depending on the number of observable AFB in each microscopic field. After three consecutive AFB negative results (ie sputum AFBx3) the sample was determined as negative.