Household carbon monoxide (CO) concentrations in a large African city: An unquantified public health burden?

Carbon monoxide (CO) is a poisonous gas produced by incomplete combustion of carbon-based fuels that is linked to mortality and morbidity. Household air pollution from burning fuels on poorly ventilated stoves can lead to high concentrations of CO in homes. There are few datasets available on household concentrations of CO in urban areas of sub-Saharan African countries. CO was measured every minute over 24 h in a sample of homes in Nairobi, Kenya. Data on household characteristics were gathered by questionnaire. Metrics of exposure were summarised and analysis of temporal changes in concentration was performed. Continuous 24-h data were available from 138 homes. The mean (SD), median (IQR) and maximum 24-h CO concentration was 4.9 (6.4), 2.8 (1.0-6.3) and 44 ppm, respectively. 50% of homes had detectable CO concentrations for 847 min (14h07m) or longer during the 24-h period, and 9% of homes would have activated a CO-alarm operating to European specifications. An association between a metric of total CO exposure and self-reported exposure to vapours >15 h per week was identified, however this were not statistically significant after adjustment for the multiple comparisons performed. Mean concentrations were broadly similar in homes from a more affluent area and an informal settlement. A model of typical exposure suggests that cooking is likely to be responsible for approximately 60% of the CO exposure of Nairobi schoolchildren. Household CO concentrations are substantial in Nairobi, Kenya, despite most homes using gas or liquid fuels. Concentrations tend to be highest during the evening, probably associated with periods of cooking. Household air pollution from cooking is the main source of CO exposure of Nairobi schoolchildren. The public health impacts of long-term CO exposure in cities in sub-Saharan Africa may be considerable and should be studied further.

Improving access to affordable quality-assured inhaled medicines in low- and middle-income countries

BACKGROUND: Access to affordable inhaled medicines for chronic respiratory diseases (CRDs) is severely limited in low- and middle-income countries (LMICs), causing avoidable morbidity and mortality. The International Union Against Tuberculosis and Lung Disease convened a stakeholder meeting on this topic in February 2022.METHODS: Focused group discussions were informed by literature and presentations summarising experiences of obtaining inhaled medicines in LMICs. The virtual meeting was moderated using a topic guide around barriers and solutions to improve access. The thematic framework approach was used for analysis.RESULTS: A total of 58 key stakeholders, including patients, healthcare practitioners, members of national and international organisations, industry and WHO representatives attended the meeting. There were 20 pre-meeting material submissions. The main barriers identified were 1) low awareness of CRDs; 2) limited data on CRD burden and treatments in LMICs; 3) ineffective procurement and distribution networks; and 4) poor communication of the needs of people with CRDs. Solutions discussed were 1) generation of data to inform policy and practice; 2) capacity building; 3) improved procurement mechanisms; 4) strengthened advocacy practices; and 5) a World Health Assembly Resolution.CONCLUSION: There are opportunities to achieve improved access to affordable, quality-assured inhaled medicines in LMICs through coordinated, multi-stakeholder, collaborative efforts.

Chronic respiratory disease in adult outpatients in three African countries: a cross-sectional study

BACKGROUND: The greatest burden of chronic respiratory disease is in low- and middle-income countries, with recent population-based studies reporting substantial levels of obstructive and restrictive lung function.OBJECTIVE: To characterise the common chronic respiratory diseases encountered in hospital outpatient clinics in three African countries.METHODS This was a cross-sectional study of consecutive adult patients with chronic respiratory symptoms (>8 weeks) attending hospital outpatient departments in Ethiopia, Kenya and Sudan. Patients were assessed using a respiratory questionnaire, spirometry and chest radiography. The diagnoses of the reviewing clinicians were ascertained.RESULT: A total of 519 patients (209 Kenya, 170 Ethiopia, 140 Sudan) participated; the mean age was 45.2 years (SD 16.2); 53% were women, 83% had never smoked. Reviewing clinicians considered that 36% (95% CI 32-40) of patients had asthma, 25% (95% CI 21-29) had chronic bronchitis, 8% (95% CI 6-11) chronic obstructive pulmonary disease (COPD), 5% (95% CI 4-8) bronchiectasis and 4% (95% CI 3-6) post-TB lung disease. Spirometry consistent with COPD was present in 35% (95% CI 30-39). Restriction was evident in 38% (95% CI 33-43). There was evidence of sub-optimal diagnosis of asthma and COPD.CONCLUSION: In Ethiopia, Kenya and Sudan, asthma, COPD and chronic bronchitis account for the majority of diagnoses in non-TB patients with chronic respiratory symptoms. The suboptimal diagnosis of these conditions will require the widespread use of spirometry.

The role and performance of chest X-ray for the diagnosis of tuberculosis: a cost-effectiveness analysis in Nairobi, Kenya

BACKGROUND

The objective of this study was to establish 1) the performance of chest X-ray (CXR) in all suspects of tuberculosis (TB), as well as smear-negative TB suspects and 2) to compare the cost-effectiveness of the routine diagnostic pathway using Ziehl-Neelsen (ZN) sputum microscopy followed by CXR if case of negative sputum result (ZN followed by CXR) with an alternative pathway using CXR as a screening tool (CXR followed by ZN).

METHODS

From TB suspects attending a chest clinic in Nairobi, Kenya, three sputum specimens were examined for ZN and culture (Lowenstein Jensen). Culture was used as gold standard. From each suspect a CXR was made using a four point scoring system: i: no pathology, ii: pathology not consistent for TB, iii: pathology consistent for TB and iv: pathology highly consistent for TB. The combined score i + ii was labeled as "no TB" and the combined score iii + iv was labeled as "TB". Films were re-read by a reference radiologist. HIV test was performed on those who consented. Laboratory and CXR costs were used to compare for cost-effectiveness.

RESULTS

Of the 1,389 suspects enrolled, for 998 (72%) data on smear, culture and CXR was complete. 714 films were re-read, showing a 89% agreement (kappa value = 0.75 s.e.0.037) for the combined scores "TB" or "no-TB". The sensitivity/specificity of the CXR score "TB" among smear-negative suspects was 80%/67%. Using chest CXR as a screening tool in all suspects, sensitivity/specificity of the score "any pathology" was 92%, respectively 63%. The cost per correctly diagnosed case was for the routine process 8.72 dollars, compared to 9.27 dollars using CXR as screening tool. When costs of treatment were included, CXR followed by ZN became more cost-effective.

CONCLUSION

The diagnostic pathway ZN followed by CXR was more cost-effective as compared to CXR followed by ZN. When cost of treatment was also considered CXR followed by ZN became more cost-effective. The low specificity of chest X-ray remains a subject of concern. Depending whether CXR was performed on all suspects or on smear-negative suspects only, 22%-45% of patients labeled as "TB" had a negative culture. The introduction of a well-defined scoring system, clinical conferences and a system of CXR quality control can contribute to improved diagnostic performance.

Planning for PPM-DOTS implementation in urban slums in Kenya: knowledge, attitude and practices of private health care providers in Kibera slum, Nairobi

SETTING

Kibera, the largest slum in Nairobi, Kenya.

OBJECTIVE

To determine the tuberculosis (TB) knowledge, attitude and practices (KAP) of private health care providers (PHCPs) to identify their training needs and willingness to participate in a National Leprosy and Tuberculosis Control Programme (NLTP) guided TB control effort in the slum.

DESIGN AND METHODOLOGY

A cross-sectional survey. The KAP of PHCPs was assessed using an interviewer administered questionnaire.

RESULTS

Of 75 PHCPs interviewed, the majority (96.0%) were paramedics; 51 (77.1%) did not consider sputum smear microscopy crucial in patients presenting with prolonged cough or when a chest X-ray was suggestive of TB; of 29 (38.7%) who indicated familiarity with the drugs used in TB treatment, 20 (58.5%) would have chosen the NLTP-recommended regimens for the treatment of the various types of TB; 16 (21.3%) PHCPs indicated that they treated TB, six (37.5%) of whom were not familiar with anti-tuberculosis drug regimens. All the PHCPs referred TB suspects to the public sector for diagnosis.

CONCLUSION

This study reveals a significant gap in TB knowledge among the PHCPs in Kibera slum. However, given appropriate training and supervision, there is potential for public-private mix for DOTS implementation in this setting.

Sex-specific performance of routine TB diagnostic tests

SETTING

City Council Chest Clinic, Nairobi, Kenya.

OBJECTIVE

To determine to what extent the performance of smear microscopy is responsible for sex differences in notification rates.

METHODOLOGY

Three sputum samples from TB suspects were subjected to smear microscopy with Ziehl-Neelsen (ZN) and auramine (FM) staining. Lowenstein-Jensen culture was used as the gold standard.

RESULTS

Of 998 suspects, 600 (60%) were men and 398 (40%) women. The odds of detecting culture-positive patients with ZN was lower for women (OR 0.67). By examining the first spot specimen, ZN detected 35% of culture-positive males and 26% of culture-positive females. These proportions increased to respectively 63% and 53% when examining three specimens, and to 79% and 74% when using FM. The sex difference reduced and became non-significant (P = 0.19) when adjusted for HIV; however, the numbers involved for HIV stratification were low.

CONCLUSION

The performance of a diagnostic tool contributes to sex differences in notification rates and influences male/female ratios. Women were less likely to be diagnosed (P = 0.08), and when ZN was used they were less likely to be labelled as smear-positive TB (P < 0.01). The application of more sensitive diagnostic tools such as FM is to the advantage of women.

Identification of MDR-TB Beijing/W and other Mycobacterium tuberculosis genotypes in Nairobi, Kenya

SETTING

Suspected tuberculosis (TB) patients in Nairobi, Kenya.

OBJECTIVE

To identify the presence of multidrug-resistant (MDR) Beijing/W type and other genotypes of Mycobacterium tuberculosis.

METHODS

Thirty-three isolates resistant to one or more drugs (resistance ratio method), including 15 MDR isolates and 40 susceptible isolates selected at random, were analysed by dot-blot hybridisation for mutations associated with resistance to isoniazid, rifampicin, streptomycin and ethambutol. All strains were genotypically classified using spoligotyping.

RESULTS

Of the 33 drug-resistant isolates, 21 (64%) were from males and 12 (36%) were from females. Mutations associated with resistance to isoniazid (katG 315) and rifampicin (rpoB526, 531) were confirmed in 83.3% and 100% of the isolates, respectively, and in 87% of the MDR isolates. Mutations were detected in 25% and 71.5% of the isolates resistant to streptomycin (rpsL43) and ethambutol (embB306), respectively. No mutations were detected in drug-susceptible isolates. Spoligotyping grouped the isolates into 25 groups. Ten of these groups corresponded to previously identified strain groups, including seven families in the international database. One of these families (CAS1) comprised six (40%) of the 15 MDR isolates. Another family (Beijing) had six (8.3%) isolates, of which two (33.3%) were MDR (Beijing/W).

CONCLUSION

This study is the first in Kenya and the second in sub-Saharan Africa to report the presence of MDR Beijing/W type and other possible drug-resistant outbreak strains. Application of the molecular techniques and markers will allow us to monitor the spread of existing drug-resistant strains and the appearance of new ones.

Is cough alone adequate to screen HIV-positive persons for tuberculosis preventive therapy in developing countries?

Although the efficacy of isoniazid in the prevention of tuberculosis in HIV-infected persons with a positive tuberculin skin test is proven, several feasibility issues remain unanswered. In resource poor settings where a chest radiograph may not be readily available, the question of whether cough alone is an adequate screening tool needs to be considered. We analysed screening data collected as part of an isoniazid efficacy study. Although the study was not designed specifically to answer this question, the data suggests that cough alone may be inadequate for screening patients for potential tuberculosis preventive therapy, and that a chest radiograph may be necessary. Feasibility studies are needed.