Translational research in Uganda: linking basic science to bedside medicine in a resource limited setting

Evaluation of an Aspergillus IgG/IgM lateral flow assay for serodiagnosis of fungal asthma in Uganda

BACKGROUND

Diagnosis of fungal allergies in asthma remains problematic in low-and middle-income countries due to non-availability of point-of-care testing. In this study, we aimed to evaluate the performance of an Aspergillus immunochromatographic technology (ICT) IgG/M lateral flow device (LFD) for the serological diagnosis of allergic bronchopulmonary aspergillosis (ABPA) and severe asthma with fungal sensitisation (SAFS) among Ugandan adult asthmatics.

METHODS

374 adult (aged ≥18years) asthmatics in the African Severe Asthma Program study, Ugandan site constituted the study population. ABPA and SAFS were diagnosed according to standard criteria. Asthmatics who did not meet the above criteria constituted a control group. The LFD tests were performed and read according to manufacturer's instructions.

RESULTS

ABPA was found in 12/374 (3.2%) and SAFS in 60/374 (16%) participants. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for the Aspergillus ICT for the diagnosis of ABPA were 0.0%, 96.4%, 0.0% and 96.7% respectively, and for SAFS 6.7%, 97.1%, 30.8% and 84.5% respectively. False positive and negative rates were 3.5% and 3.2% for ABPA and 2.4% and 14.9% for SAFS, respectively. Patients with a positive LFD significantly had higher median Aspergillus fumigatus-specific IgE levels compared to those with negative LFD (median: 0.06 kUA/l VS 0.03 kUA/L, P = 0.011).

CONCLUSION

The Aspergillus ICT IgG/M LFD had a poor diagnostic performance for the diagnosis of both ABPA and SAFS. Its greatest value may be in distinguishing chronic and allergic aspergillosis in Africa.

Fungal asthma among Ugandan adult asthmatics

Fungal sensitization is associated with poor asthma control. We aimed to determine the prevalence and factors associated with fungal asthma among Ugandan adults. Individuals aged ≥18 years with a new diagnosis of asthma in the last 12 months participating in the African Severe Asthma Program constituted the study population. Skin prick test results, clinical and demographic data were retrieved from the database, and serum Aspergillus fumigatus specific antibodies and total IgE were measured in stored blood. We enrolled 374 patients, median (IQR) age 34 (25-45) years, 286 (76.5%) females and 286 (76.5%) with severe asthma. Prevalence of Aspergillus fumigatus sensitization was 42.0% (95% CI: 37.1-47.0%), allergic bronchopulmonary aspergillosis (ABPA) 3.2% (1.8-5.5%), severe asthma with fungal sensitization (SAFS) 16% (12.7-20.1%) and allergic bronchopulmonary mycosis (ABPM) 2.9% (1.7-5.2%). Older age (55-64 years) (crude odds ratio (cOR) = 2.6), sensitization to at least one allergen (cOR = 9.38) and hypertension (cOR = 1.99) were significantly associated with Aspergillus sensitization, whereas tertiary education level (cOR = 0.29), severe depression (cOR = 0.15) and strong emotions (cOR = 0.47) were not. High occupational exposure to Aspergillus (cOR = 4.26) and contact with moulds (cOR = 14.28) were significantly associated with ABPA. Palpitations (cOR = 5.54), uncontrolled asthma (cOR = 3.54), eczema/dermatitis (cOR = 3.07), poor lung function (cOR = 2.11) and frequent exacerbations (cOR = 1.01) were significantly associated with SAFS. Eczema/dermatitis (cOR = 1.55) was significantly associated with ABPM, but cold weather trigger (cOR = 0.24) was not. Fungal asthma is a significant problem among Ugandans with asthma and should be particularly considered in individuals who remain uncontrolled despite optimal standard of care for asthma, as it is responsive to available and affordable oral antifungal therapy.

LAY SUMMARY

This study showed that fungal asthma is a significant problem among Ugandans with asthma with a high prevalence. Fungal asthma should be considered in patients with uncontrolled asthma despite receiving optimal standard of care. This is the first modern attempt to define these endotypes of asthma in Africa.

Misdiagnosis of chronic pulmonary aspergillosis as pulmonary tuberculosis at a tertiary care center in Uganda: a case series

BACKGROUND

Diagnosis of chronic pulmonary aspergillosis (CPA) is based on a combination of clinical symptomatology, compatible chest imaging findings, evidence of Aspergillus infection and exclusion of alternative diagnosis, all occurring for more than 3 months. Recently, a rapid, highly sensitive and specific point-of-care lateral flow device (LFD) has been introduced for the detection of Aspergillus-specific immunoglobulin (Ig)G, especially in resource-limited settings where CPA is underdiagnosed and often misdiagnosed as smear-negative pulmonary tuberculosis (PTB). Therefore, in our setting, where tuberculosis (TB) is endemic, exclusion of PTB is an important first step to the diagnosis of CPA. We used the recently published CPA diagnostic criteria for resource-limited settings to identify patients with CPA in our center.

CASE PRESENTATION

Three Ugandan women (45/human immunodeficiency virus (HIV) negative, 53/HIV infected and 18/HIV negative), with a longstanding history of cough, chest pain, weight loss and constitutional symptoms, were clinically and radiologically diagnosed with PTB and empirically treated with an anti-tuberculous regimen despite negative microbiological tests. Repeat sputum Mycobacteria GeneXpert assays were negative for all three patients. On further evaluation, all three patients met the CPA diagnostic criteria with demonstrable thick-walled cavities and fungal balls (aspergilomas) on chest imaging and positive Aspergillus-specific IgG/IgM antibody tests. After CPA diagnosis, anti-TB drugs were safely discontinued for all patients, and they were initiated on capsules of itraconazole 200 mg twice daily with good treatment outcomes.

CONCLUSIONS

The availability of simple clinical diagnostic criteria for CPA and a LFD have the potential to reduce misdiagnosis of CPA and in turn improve treatment outcomes in resource-limited settings.