Screening for pulmonary tuberculosis among HIV-infected pregnant women in Western Kenya

Abstract

Background: Pulmonary tuberculosis (PTB) is the most common opportunistic infection affecting HIV-infected patients including pregnant women, yet screening for PTS is not routinely or systematically done in most Prevention of Mother-To- Child Transmission of HIV/AIDS (PMTCT) programs. Diagnosis of PTB among HIV-infected pregnant women poses unique challenges including: confusion of constitutional symptoms of tuberculosis (TB) with those of early pregnancy, reluctance to perform radiographic screening, lack of access to TB culture in resource-poor settings and the paucibacillary nature of PTB among HIV-infected patients leading to lower smear positivity rates than their negative counterparts. Objectives: Among HIV-infected pregnant women participating in a standard PTS screening program in Western Kenya to determine the: 1) prevalence of latent tuberculosis infection (LTBI); 2) prevalence of active PTB and 3) sensitivity, specificity and predictive value of the diagnostic tests in the diagnosis of active PTB. Methods: This is a cross-sectional study with an analytic component carried out in Eldoret and Busia PMTCT clinics within the USAID-AMPATH partnership; Western Kenya. All eligible HIV-infected pregnant women receiving care during the five month study period and consented underwent: a standardized structured symptom and sign screen, tuberculin skin test (mantoux), single view posterior anterior dose regulated chest radiograph (CXR) performed after the first trimester and sputum smear and cultures when cough was present. Results: A total of 190 patients who met the eligibility criteria and consented were enrolled. The study participants had a mean age of 27 years and a median (range): age of 25(15-43) years; parity of 2 (0, 10); gravidity of 3 (1, 11); gestation at enrollment of 26(10, 41) weeks and CD4 counts of 440 (24, 1408) cells/lJl. Only 20% of the study respondents had a positive symptom and sign screen. The prevalence of: LTBI as defined by a positive mantoux skin test was 40% and of presumptive active TB as defined by suggestive chest radiograph findings was 5%. There was a notable representation of milliary TB; of the 10 cases with suggestive radiological features of active TB 3 had a milliary picture. None of the 28 samples of sputum's collected were positive for Ziehl-Neelsen staining or for mycobacterium tuberculosis culture. The role of different screening procedures was inconclusive due to a small number of those with active TB and the fact that there was no microbiological evidence of active TB. Conclusion and Recommendation: LTBI infection is common in this population with a remarkable percentage of chest radiographs suggestive of TB and a notable milliary presentation. TB screening should be routine in all PMTCT care programs in high TB and HIV burden areas. More studies are required to determine best screening protocols as well as feasibility of Isoniazid Preventive Therapy (IPT) in this population.