A study of 87 mycetoma patients seen at three health facilities in Nouakchott, Mauritania

An updated list of eumycetoma causative agents and their differences in grain formation and treatment response

SUMMARYIn 2023, the World Health Organization designated eumycetoma causative agents as high-priority pathogens on its list of fungal priority pathogens. Despite this recognition, a comprehensive understanding of these causative agents is lacking, and potential variations in clinical manifestations or therapeutic responses remain unclear. In this review, 12,379 eumycetoma cases were reviewed. In total, 69 different fungal species were identified as causative agents. However, some were only identified once, and there was no supporting evidence that they were indeed present in the grain. Madurella mycetomatis was by far the most commonly reported fungal causative agent. In most studies, identification of the fungus at the species level was based on culture or histology, which was prone to misidentifications. The newly used molecular identification tools identified new causative agents. Clinically, no differences were reported in the appearance of the lesion, but variations in mycetoma grain formation and antifungal susceptibility were observed. Although attempts were made to explore the differences in clinical outcomes based on antifungal susceptibility, the lack of large clinical trials and the inclusion of surgery as standard treatment posed challenges in drawing definitive conclusions. Limited case series suggested that eumycetoma cases caused by Fusarium species were less responsive to treatment than those caused by Madurella mycetomatis. However, further research is imperative for a comprehensive understanding.

Mycetoma and the environment

Mycetoma is a chronic, incapacitating, destructive inflammatory disease with many serious damaging impacts. Currently, there is no control or prevention program as many of its epidemiological characteristics, such as the causative organisms' ecological niche, natural habitat, primary reservoir, transmission mode, geographical distribution, incidence, and prevalence, remain unclear. This may be due to a lack of research interest, as mycetoma is still a neglected disease and the scarcity of accurate molecular diagnostic techniques in disease-endemic regions for accurate causative microorganisms identification and mapping. With this background, this study set out to address this knowledge gap by considering the mycetoma environmental occurrence predictors. The medical literature obtained data showed a close association between mycetoma occurrence and its environment. The causative microorganisms are available in the environment in active or dormant forms. Animal dung may be a natural niche and reservoir for these organisms, and thorns may facilitate the subcutaneous inoculation. Some environmental factors, such as the soil type and consistency, temperature, water sources, aridity index, and thorny trees, may be risk factors. The population in endemic areas socioeconomic, hygiene, and health education status are contributory factors for mycetoma. The individual's genetic and immunological backgrounds may determine the disease's susceptibility and resistance. Environmental conditions and personal hygiene improvement are mandatory to reduce disease occurrence. Mycetoma spatial mapping can detect disease cluster areas and then develop public health strategies for early case detection and management to reduce the disease burden. More research interests and facilities are needed to understand disease pathogenesis and appropriate patient management better.

Epidemiologic Aspects of Mycetoma in Africa

Mycetoma is a chronic, disabling infection caused by fungi or actinomycetes that affects the disadvantaged rural populations of arid tropical regions. The identification of etiological agents is long, difficult, and often imprecise or unsuccessful. Recently developed molecular methods can be used to identify causal agents at the species level. However, diagnosis can only be implemented in specialized laboratories. For these reasons, the distribution of causal agents in endemic African countries remains approximate. It is known that the pathogenic organisms of mycetoma are present in the environment, introduced as a result of injuries or trauma. There are still unknowns concerning the natural habitats of agents and the mode of infection. A potential association between mycetoma and acacia was uncovered in Sudan, allowing the elaboration of a risk map of the country. A new hypothesis for the mode of contamination involves the intervention of an intermediate host. The first surveys in Sudanese endemic villages gave a higher prevalence than the previous estimates, indicating that the prevalence of mycetoma in endemic African countries has previously been underestimated.

Estimating the burden of mycetoma in Sudan for the period 1991-2018 using a model-based geostatistical approach

Mycetoma is widespread in tropical and subtropical regions favouring arid areas with low humidity and a short rainy season. Sudan is one of the highly endemic countries for mycetoma. Estimating the population at risk and the number of cases is critical for delivering targeted and equitable prevention and treatment services. In this study, we have combined a large dataset of mycetoma cases recorded by the Mycetoma Research Centre (MRC) in Sudan over 28 years (1991-2018) with a collection of environmental and water and hygiene-related datasets in a geostatistical framework to produce estimates of the disease burden across the country. We developed geostatistical models to predict the number of cases of actinomycetoma and eumycetoma in areas considered environmentally suitable for the two mycetoma forms. Then used the raster dataset (gridded map) with the population estimates for 2020 to compute the potentially affected population since 1991. The geostatistical models confirmed this heterogeneous and distinct distribution of the estimated cases of eumycetoma and actinomycetoma across Sudan. For eumycetoma, these higher-risk areas were smaller and scattered across Al Jazirah, Khartoum, White Nile and Sennar states, while for actinomycetoma a higher risk for infection is shown across the rural districts of North and West Kurdufan. Nationally, we estimated 63,825 people (95%CI: 13,693 to 197,369) to have been suffering from mycetoma since 1991 in Sudan,51,541 people (95%CI: 9,893-166,073) with eumycetoma and 12,284 people (95%CI: 3,800-31,296) with actinomycetoma. In conclusion, the risk of mycetoma in Sudan is particularly high in certain restricted areas, but cases are ubiquitous across all states. Both prevention and treatment services are required to address the burden. Such work provides a guide for future control and prevention programs for mycetoma, highly endemic areas are clearly targeted, and resources are directed to areas with high demand.

Reporting of mycetoma cases from skin and soft tissue biopsies over a period of ten years: A single center report and literature review from Pakistan

Background

Mycetoma is an important neglected tropical disease associated with debilitation, disfigurement and death if not diagnosed and treated adequately. In Pakistan, mycetoma cases have frequently been diagnosed in histopathology and microbiology laboratories. However, there is scarcity of published data from this country. Therefore, the objectives of this study were to evaluate the frequency and type of mycetoma reported in skin and soft tissue biopsies from a single center over 10 years and review of published literature from Pakistan.

Method

This descriptive observational retrospective study was conducted at the Aga Khan University Hospital laboratory, Karachi, Pakistan. Laboratory data from 2009–2018 of skin and soft tissue biopsies with positive findings of mycetoma were retrieved from hospital information system. The variables for statistical analysis were age and gender of patient, anatomical site of lesion, residence of patient (geographical location) in the country, etiologic agents of mycetoma and significant gross and microscopic histopathological findings. The data was entered, and descriptive epidemiologic assessment was carried out using MS excel 2013. Geographical information system was used for mapping the location. Literature review of mycetoma cases reported from Pakistan was done on PubMed, Google search and PakMediNet from 1980 till April 2019.

Result

During ten years of study period, 89 skin and soft tissue biopsies were reported as mycetoma, majority were eumycetoma [n = 66/89 (74%)] followed by actinomycetoma [n = 23/89 (26%)]. Involvement of lower limb was predominantly observed [n = 74/89 (83%)] in which foot had significant contribution [n = 65/74 (88%)]. Only 18 specimens were submitted for microbiological assessment and six grew agents of mycetoma, with Madurella mycetomatis reported in only three. Well-formed granuloma formation was observed in only 26%[n = 23/89] of cases. Specific geographical location was not identified, and cases were reported from across the country. From Pakistan, only two original papers and 7 case reports were available in published literature.

Conclusion

This single center study reports a handful of cases of mycetoma from Pakistan. We conclude that the index of suspicion should remain high among treating surgeons and physicians and clinical laboratories should improve their diagnostic capacity and skills. This will have a great impact on disease outcome and patient’s life.

World Health Organization (WHO) has included Mycetoma in the neglected tropical diseases. Epidemiological data of mycetoma cases from Pakistan is not available. Although physicians and surgeons frequently see cases of mycetoma in their clinical practice, but poor socioeconomic conditions of patients restrict laboratory diagnosis such as histopathological and microbiological confirmation of disease. This leads to disability, disfigurement and at times limb loss or mortality. Through this study we are documenting the diagnosed cases of mycetoma from specimens submitted to our laboratory. The diagnosis was mainly made by histopathological examination of samples. It is disappointing to note that mycetoma was not included in the differential diagnosis list of clinicians. Probably, that is the reason that very few samples were submitted to the microbiology laboratory for the culture to find out etiologic agents of eumycetoma and actinomycetoma. Overall, this study has highlighted the gaps in the clinical as well as laboratory diagnosis of this disease and case management.

Eumycetoma Medical Treatment: Past, Current Practice, Latest Advances and Perspectives

Mycetoma is a neglected tropical disease that is associated with poor communities and socioeconomically impaired individuals in the tropical and sub-tropical areas. Interestingly, the disease is caused by either bacteria (actinomycetoma) or fungus (eumycetoma). The latter form of the disease, eumycetoma, is the most common type in Africa. Eumycetoma is characterized by a prolonged disease duration and low cure rate. The effective case management of eumycetoma largely depends on the accurate diagnosis and identification of the causative agent to the species level and evaluating its susceptibility to the available drugs. This review summarizes the currently available and used antifungal agents for the treatment of eumycetoma and discusses optimizing the newly developed antifungals as a potential second line for eumycetoma treatment.