Neglected Fungal Diseases in Sub-Saharan Africa: A Call to Action

The estimated burden of fungal diseases in Mali

Mali is a developing country facing several health challenges with a high rate of tuberculosis (TB) and a moderate HIV infection burden. Little is known or done about fungal diseases, yet they represent a significant public health problem in certain populations. The aim of this study was to estimate the national burden of fungal disease, and summarize data, diagnostic and treatment gaps. We used national demographics and PubMed searches to retrieve articles on published data on these infections and at-risk populations (pulmonary TB, HIV/AIDS patients, patients receiving critical care etc.) in Mali. The estimated Malian population was 21,251,000 in 2020 (UN), of which 45% were children <14 years. Among HIV patients, we estimate an annual incidence of 611 cryptococcosis, 1393 Pneumocystis pneumonia, 180 histoplasmosis and >5,700 esophageal candidiasis and some microsporidiosis cases. Our prevalence estimates for tinea capitis are 2.3 million, for recurrent vulvovaginal candidiasis 272,460, ∼60,000 fungal asthma and 7,290 cases of chronic pulmonary aspergillosis (often mistaken for TB). Less common acute fungal infections are probably invasive aspergillosis (n=1230), fungal keratitis (n=2820), candidaemia (>1,060) and mucormycosis (n=43). Histoplasmin was found in 6% in general population. A few cases of mycetoma are described in Mali. Many WHO Essential medicines and Diagnostics are not available in Mali. This shows a marked disparity in documented and estimated cases of fungal diseases in Mali. These infections are underestimated due to the lack of accurate diagnosis tools and lack of support for fungal diseases diagnosis and management.

Point of care tests for invasive fungal infections: a blueprint for increasing availability in Africa

Invasive fungal infections (IFIs) such as cryptococcosis, disseminated histoplasmosis, and chronic pulmonary aspergillosis are significant causes of morbidity and mortality in Africa. Lack of laboratory infrastructure and laboratory personnel trained in diagnostic mycology hamper prompt detection and management of IFIs on the continent. Point-of-care tests (POCT) obviate the need for complex infrastructure, skilled technicians, and stable electricity and have had major impacts on the diagnosis of bacterial, viral, and parasitic infections in low- and middle-income countries. Over the last 10 years, POCTs for IFIs have become increasingly available and they have the potential to revolutionize the management of these infections if scaled up in Africa. At the beginning of 2021, the World Health Organization (WHO) Essential Diagnostic List (EDL) included a cryptococcal antigen test for the diagnosis of cryptococcosis, Histoplasma antigen test for the diagnosis of disseminated histoplasmosis, and Aspergillus-specific test for the diagnosis of chronic pulmonary aspergillosis. All of these are available in formats that may be used as POCTs and it is hoped that this will improve the diagnosis of these life-threatening IFIs, especially in low- and middle-income countries. This perspective review discusses commercially available POCTs and outlines strategies of a blueprint to achieve their roll-out in Africa. The strategies include raising awareness, conducting research that uncovers the exact burden of IFIs, increasing advocacy, integrating diagnosis of IFIs into existing public health programs, adoption of the WHO EDL at country levels, and improving logistics and supply chains.

Current burden of serious fungal infections in Republic of Congo

BACKGROUND

The Republic of Congo (RoC) is characterised by a high prevalence of tuberculosis and HIV/AIDS, which largely drive the epidemiology of serious fungal infections.

OBJECTIVE

We aimed to estimate the current burden of serious fungal infections in RoC.

MATERIAL AND METHODS

Using local, regional or global data and estimates of population and at-risk population groups, deterministic modelling was employed to estimate national incidence or prevalence of the most serious fungal infections.

RESULTS

Our study revealed that about 5.4% of the Congolese population (283 450) suffer from serious fungal infections yearly. The incidence of cryptococcal meningitis, Pneumocystis jirovecii pneumonia and disseminated histoplasmosis in AIDS patients was estimated at 560, 830 and 120 cases per year. Oral and oesophageal candidiasis collectively affects 12 320 HIV-infected patients. Chronic pulmonary aspergillosis, 67% post-tuberculosis, probably has a prevalence of 3420. Fungal asthma (allergic bronchopulmonary aspergillosis and severe asthma with fungal sensitisation) probably has a prevalence of 3640 and 4800, although some overlap due to disease definition is likely. The estimated prevalence of recurrent vulvovaginal candidiasis and tinea capitis is 85 440 and 178 400 respectively. Mostly related to agricultural activity, fungal keratitis affects an estimated 700 Congolese yearly.

CONCLUSION

These data underline the urgent need for an intensified awareness towards Congolese physicians to fungal infections and for increased efforts to improve diagnosis and management of fungal infections in the RoC.

Looking for fungi in all the right places: screening for cryptococcal disease and other AIDS-related mycoses among patients with advanced HIV disease

PURPOSE OF REVIEW

As HIV treatment programmes scale up to meet the UNAIDS 90-90-90 goals, care must be taken to start antiretroviral treatment safely in patients with advanced disease (CD4 counts <200 cells/μl) who are simultaneously at risk for opportunistic infections and immune reconstitution inflammatory syndrome. Invasive fungal diseases pose a great threat at this critical time point, though the development of inexpensive and highly accurate rapid diagnostic tests has changed the approach HIV programmes are taking to reduce the high mortality associated with these opportunistic infections. This article summarizes recent advances and findings in fungal opportunistic infection diagnostics with a focus on screening to prevent cryptococcal meningitis.

RECENT FINDINGS

Cryptococcal antigen (CrAg) screening using a lateral flow assay platform is cost-effective and feasible to implement as either a laboratory reflex or point-of-care test. Recent CrAg screening pilots have elucidated the varying prevalence of cryptococcal antigenemia across geographic regions, which may aid programme planning. Evidence from recently completed clinical trials provides a strong motivation for the use of CrAg titer to refine treatment options for patients with subclinical cryptococcal disease.

SUMMARY

Although several operational barriers to programme effectiveness still need to be addressed, the utility of CrAg screening using inexpensive and accurate antigen assays has been demonstrated in real-world HIV programmes, paving the way for development and testing of other fungal opportunistic infection screening strategies and for an integrated advanced HIV disease testing package to reduce AIDS mortality and ensure safe antiretroviral treatment initiation.

Improvement of fungal disease identification and management: combined health systems and public health approaches

More than 1·6 million people are estimated to die of fungal diseases each year, and about a billion people have cutaneous fungal infections. Fungal disease diagnosis requires a high level of clinical suspicion and specialised laboratory testing, in addition to culture, histopathology, and imaging expertise. Physicians with varied specialist training might see patients with fungal disease, yet it might remain unrecognised. Antifungal treatment is more complex than treatment for bacterial or most viral infections, and drug interactions are particularly problematic. Health systems linking diagnostic facilities with therapeutic expertise are typically fragmented, with major elements missing in thousands of secondary care and hospital settings globally. In this paper, the last in a Series of eight papers, we describe these limitations and share responses involving a combined health systems and public health framework illustrated through country examples from Mozambique, Kenya, India, and South Africa. We suggest a mainstreaming approach including greater integration of fungal diseases into existing HIV infection, tuberculosis infection, diabetes, chronic respiratory disease, and blindness health programmes; provision of enhanced laboratory capacity to detect fungal diseases with associated surveillance systems; procurement and distribution of low-cost, high-quality antifungal medicines; and concomitant integration of fungal disease into training of the health workforce.

Development and Evaluation of a Molecular Diagnostic Method for Rapid Detection of Histoplasma capsulatum var. farciminosum, the Causative Agent of Epizootic Lymphangitis, in Equine Clinical Samples

Histoplasma capsulatum var. farciminosum, the causative agent of epizootic lymphangitis (EZL), is endemic in parts of Africa. Diagnosis based on clinical signs and microscopy lacks specificity and is a barrier to further understanding this neglected disease. Here, a nested PCR method targeting the internal transcribed spacer (ITS) region of the rRNA operon was validated for application to equine clinical samples. Twenty-nine horses with signs of EZL from different climatic regions of Ethiopia were clinically examined. Blood samples and aspirates of pus from cutaneous nodules were taken, along with blood from a further 20 horses with no cutaneous EZL lesions. Among the 29 horses with suspected cases of EZL, H. capsulatum var. farciminosum was confirmed by extraction of DNA from pus and blood samples from 25 and 17 horses, respectively. Positive PCR results were also obtained with heat-inactivated pus (24 horses) and blood (23 horses) spotted onto Whatman FTA cards. Two positive results were obtained among blood samples from 20 horses that did not exhibit clinical signs of EZL. These are the first reports of the direct detection of H. capsulatum var. farciminosum in equine blood and at high frequency among horses exhibiting cutaneous lesions. The nested PCR outperformed conventional microscopic diagnosis, as characteristic yeast cells could be observed only in 14 pus samples. The presence of H. capsulatum var. farciminosum DNA was confirmed by sequencing the cloned PCR products, and while alignment of the ITS amplicons showed very little sequence variation, there was preliminary single nucleotide polymorphism-based evidence for the existence of two subgroups of H. capsulatum var. farciminosum. This molecular diagnostic method now permits investigation of the epidemiology of EZL.