Histoplasmosis in Africa: An emerging or a neglected disease?

Histoplasmosis around the world: A global perspective on the presentation, virulence factors, and treatment of histoplasmosis

Histoplasmosis is a systemic infection caused by an endemic dimorphic fungus, Histoplasma capsulatum. Though prevalent in the eastern United States of America, near the Ohio and Mississippi River Valleys, the evidence underlying the global prevalence of histoplasmosis, especially in immunocompromised populations, is underappreciated. This article highlights the global epidemiology, risk factors, microbiology and pathophysiological characteristics, pulmonary and extrapulmonary manifestations, prevention measures, radiographic patterns, diagnostic techniques, and antifungal treatment approaches for Histoplasma capsulatum.

Invasive fungal disease in the immunocompromised host: changing epidemiology, new antifungal therapies, and management challenges

BACKGROUND

Invasive fungal disease (IFD) causes morbidity and mortality in immunocompromised hosts (ICHs). Based on increasing recognition of the impact of IFD on human disease, a recent WHO priority list identified key areas of need.

OBJECTIVES

This review examines changes in the epidemiology of IFD, in particular the emergence of antifungal-resistant pathogens and the current availability of rapid diagnostic tests and antifungal treatment options.

SOURCES

Literature between 2000 and January 2024 regarding fungal epidemiology, diagnostic tests, antifungal resistance, emerging fungal pathogens, and novel antifungal agents in both adult and paediatric ICH were reviewed.

CONTENT

We describe the changing epidemiology and continued burden and mortality of IFD in ICH. Furthermore, we discuss the emergence of antifungal-resistant organisms driven by new immunosuppressed populations, climate change, and antifungal exposure in the individual and environment. We highlight novel antifungal agents and how they will address current unmet needs.

IMPLICATIONS

The changing epidemiology and increased population at risk for IFD, lack of recognition or quantification of risks for IFD with new therapies, current gaps in the availability of rapid diagnostic tests, and the imminent availability of novel antifungals with distinct spectra of activity argue for improved availability of and access to rapid diagnostics, antifungal stewardship programmes, and global access to antifungal agents.

The gut-lung axis: the impact of the gut mycobiome on pulmonary diseases and infections

The gastrointestinal tract contains a diverse microbiome consisting of bacteria, fungi, viruses and archaea. Although these microbes usually reside as commensal organisms, it is now well established that higher abundance of specific bacterial or fungal species, or loss of diversity in the microbiome can significantly affect development, progression and outcomes in disease. Studies have mainly focused on the effects of bacteria, however, the impact of other microbes, such as fungi, has received increased attention in the last few years. Fungi only represent around 0.1% of the total gut microbial population. However, key fungal taxa such as Candida, Aspergillus and Wallemia have been shown to significantly impact health and disease. The composition of the gut mycobiome has been shown to affect immunity at distal sites, such as the heart, lung, brain, pancreas, and liver. In the case of the lung this phenomenon is referred to as the 'gut-lung axis'. Recent studies have begun to explore and unveil the relationship between gut fungi and lung immunity in diseases such as asthma and lung cancer, and lung infections caused by viruses, bacteria and fungi. In this review we will summarize the current, rapidly growing, literature describing the impact of the gut mycobiome on respiratory disease and infection.

The WHO fungal priority pathogens list: a crucial reappraisal to review the prioritisation

In October, 2022, WHO published the first fungal priority pathogen list, which categorised 19 fungal entities into three priority groups (critical, high, and medium), for prioritisation of research efforts. The final ranking was determined via multiple criteria decision analysis, considering both research and development needs and perceived public health importance. In this Personal View, we discuss the positioning of the fungal pathogens, namely, Mucorales, Candida spp, Histoplasma spp, Coccidioides and Paracoccidioides spp, Fusarium spp, eumycetoma causative agents, Talaromyces marneffei, and Pneumocystis jirovecii, while expressing concerns about potential disparities between the WHO fungal priority pathogen list ranking and the actual disease burden associated with these pathogens. Finally, we propose a revised prioritisation list that also considers the regional disparities in the burden of fungal diseases.

Histoplasmosis: A systematic review to inform the World Health Organization of a fungal priority pathogens list

Histoplasmosis, a significant mycosis primarily prevalent in Africa, North and South America, with emerging reports globally, poses notable health challenges, particularly in immunocompromised individuals such as people living with HIV/AIDS and organ transplant recipients. This systematic review, aimed at informing the World Health Organization's Fungal Priority Pathogens List, critically examines literature from 2011 to 2021 using PubMed and Web of Science, focusing on the incidence, mortality, morbidity, antifungal resistance, preventability, and distribution of Histoplasma. We also found a high prevalence (22%-44%) in people living with HIV, with mortality rates ranging from 21% to 53%. Despite limited data, the prevalence of histoplasmosis seems stable, with lower estimates in Europe. Complications such as central nervous system disease, pulmonary issues, and lymphoedema due to granuloma or sclerosis are noted, though their burden remains uncertain. Antifungal susceptibility varies, particularly against fluconazole (MIC: ≥32 mg/l) and caspofungin (MICs: 4-32 mg/l), while resistance to amphotericin B (MIC: 0.125-0.16 mg/l), itraconazole (MICs: 0.004-0.125 mg/l), and voriconazole (MICs: 0.004-0.125 mg/l) remains low. This review identifies critical knowledge gaps, underlining the need for robust, globally representative surveillance systems to better understand and combat this fungal threat.

Phenotypic characterization of cryptic species in the fungal pathogen Histoplasma

Histoplasmosis is an endemic mycosis that often presents as a respiratory infection in immunocompromised patients. Hundreds of thousands of new infections are reported annually around the world. The etiological agent of the disease, Histoplasma, is a dimorphic fungus commonly found in the soil where it grows as mycelia. Humans can become infected by Histoplasma through inhalation of its spores (conidia) or mycelial particles. The fungi transition into the yeast phase in the lungs at 37°C. Once in the lungs, yeast cells reside and proliferate inside alveolar macrophages. Genomic work has revealed that Histoplasma is composed of at least five cryptic phylogenetic species that differ genetically. Three of those lineages have received new names. Here, we evaluated multiple phenotypic characteristics (colony morphology, secreted proteolytic activity, yeast size, and growth rate) of strains from five of the phylogenetic species of Histoplasma to identify phenotypic traits that differentiate between these species: Histoplasma capsulatum sensu stricto, Histoplasma ohiense, Histoplasma mississippiense, Histoplasma suramericanum, and an African lineage. We report diagnostic traits for three species. The other two species can be identified by a combination of traits. Our results suggest that (i) there are significant phenotypic differences among the cryptic species of Histoplasma and (ii) those differences can be used to positively distinguish those species in a clinical setting and for further study of the evolution of this fungal pathogen.IMPORTANCEIdentifying species boundaries is a critical component of evolutionary biology. Genome sequencing and the use of molecular markers have advanced our understanding of the evolutionary history of fungal pathogens, including Histoplasma, and have allowed for the identification of new species. This is especially important in organisms where morphological characteristics have not been detected. In this study, we revised the taxonomic status of the four named species of the genus Histoplasma, H. capsulatum sensu stricto (ss), H. ohiense, H. mississippiense, and H. suramericanum, and propose the use of species-specific phenotypic traits to aid their identification when genome sequencing is not available. These results have implications not only for evolutionary study of Histoplasma but also for clinicians, as the Histoplasma species could determine the outcome of disease and treatment needed.

Itraconazole in human medicine and veterinary practice

Diagnosis and management of fungal infections are challenging in both animals and humans, especially in immunologically weakened hosts. Due to its broad spectrum and safety profile when compared to other antifungals, itraconazole (ITZ) has been widely used in the treatment and prophylaxis of fungal infections, both in human and veterinary medicine. The dose and duration of management depend on factors such as the type of fungal pathogen, the site of infection, sensitivity to ITZ, chronic stages of the disease, the health status of the hosts, pharmacological interactions with other medications and the therapeutic protocol used. In veterinary practice, ITZ doses generally vary between 3 mg/kg and 50 mg/kg, once or twice a day. In humans, doses usually vary between 100 and 400 mg/day. As human and veterinary fungal infections are increasingly associated, and ITZ is one of the main medications used, this review addresses relevant aspects related to the use of this drug in both clinics, including case reports and different clinical aspects available in the literature.

Histoplasma seropositivity and environmental risk factors for exposure in a general population in Upper River Region, The Gambia: A cross-sectional study

Robust surveillance of Histoplasma species is warranted in endemic regions, including investigation of community-level transmission dynamics. This cross-sectional study explored anti-Histoplasma antibody seroprevalence and risk factors for exposure in a general population in Upper River Region (URR), The Gambia. Study participants were recruited (December 2022-March 2023) by random household sampling across 12 Enumeration Areas (EAs) of URR. A questionnaire and clinical examination were performed; exploring demographic, clinical and environmental risk factors for Histoplasma exposure. One venous blood sample per participant was subject to IMMY Latex Agglutination Histoplasma test to determine presence of a recent IgM response to Histoplasma. Seropositivity risk factors were explored by multi-level, multivariable logistic regression analysis. The study population (n = 298) aged 5-83 years, demonstrated a positively skewed age distribution and comprised 55.4% females. An apparent seroprevalence of 18.8% (n = 56/298, 95% CI 14.5-23.7%) was measured using the LAT. A multivariable model demonstrated increased odds of Histoplasma seropositivity amongst female participants (OR = 2.41 95% CI 1.14-5.10); and participants reporting involvement in animal manure management (OR = 4.21 95% CI 1.38-12.90), and management of domestic animals inside the compound at night during the dry season (OR = 10.72 95% CI 2.02-56.83). Increasing age (OR = 0.96 95% CI 0.93-0.98) was associated with decreased odds of seropositivity. Clustering at EA level was responsible for 17.2% of seropositivity variance. The study indicates frequent recent Histoplasma exposure and presents plausible demographic and environmental risk factors for seropositivity. Histoplasma spp. characterisation at this human-animal-environment interface is warranted, to determine public health implications of environmental reservoirs in The Gambia. The study was supported by Wellcome Trust (206,638/Z/17/Z to CES) and a University of Liverpool-funded PhD studentship (to TRC).

Frequency of fungal pathogens in autopsy studies of people who died with HIV in Africa: a scoping review

BACKGROUND

Fungal infections are common in HIV-infected individuals and significantly contribute to mortality. However, a substantial number of cases are undiagnosed before death.

OBJECTIVE

To determine the frequency of fungal pathogens in autopsy studies of people who died with HIV in Africa.

METHODS

We conducted a scoping review of autopsy studies conducted in Africa.

DATA SOURCES

PubMed, Scopus, Web of Science, Embase, Google Scholar, and African Journal Online.

STUDY ELIGIBILITY CRITERIA

The review encompasses studies published from inception to September 2023, and no language restrictions were imposed during the search process. We included studies that reported histopathological or microbiological evidence for the diagnosis of fungal infections and other pathogens.

DATA SYNTHESIS

Data were summarized using descriptive statistics and no meta-analysis was performed.

RESULTS

We examined 30 articles reporting studies conducted between 1991 and 2019, encompassing a total of 13 066 HIV-infected decedents across ten African countries. In five studies, the autopsy type was not specified. Among those studies with specified autopsy types, 20 involved complete diagnostic autopsies, whereas 5 were categorized as partial or minimally invasive autopsies. There were 2333 pathogens identified, with 946 (40.5%) being mycobacteria, 856 (36.7%) fungal, 231 (3.8%) viral, 208 (8.9%) parasitic, and 92 (3.9%) bacterial. Of the 856 fungal pathogens identified, 654 (28.0%) were Cryptococcus species, 167 (7.2%) Pneumocystis jirovecii, 16 (0.69%) Histoplasma species, 15 (0.64%) Aspergillus species, and 4 (0.17%) Candida species. Other major non-fungal pathogens identified were cytomegalovirus 172 (7.37%) and Toxoplasma gondii 173 (7.42%).

CONCLUSIONS

Invasive fungal infections occur in over one-third of people who succumb to HIV in Africa. In addition to cryptococcosis and Pneumocystis jirovecii pneumonia, integrating other priority fungal pathogen detection and management strategies into the broader framework of HIV care in Africa is recommended. This involves increasing awareness regarding the impact of fungal infections in advanced HIV disease and strengthening diagnostic and treatment capacity.

Disseminated Histoplasmosis Infection Diagnosed by Metagenomic Next-Generation Sequencing: A Case Report

Histoplasmosis is an endemic disease caused by Histoplasma capsulatum. This systemic disease can affect various organs beyond the lungs, such as the liver, spleen, adrenal gland, and lymph nodes. The clinical symptoms can range from asymptomatic to severe, life-threatening conditions, depending on the state of the patient's immune system. This report describes a 40-year-old male who presented with reports of weight loss, low back pain, and progressively worsening movement disorder of the bilateral lower extremities for months. Computed tomography (CT) examination showed multiple lytic lesions of vertebral bodies, bilateral ribs, and pelvic bone, histopathological examination and tumor-related serum markers exclude tumors. mNGS was employed to identify H. capsulatum var. capsulatum as the etiological agent of the lesions in the bone biopsy. Through phylogenetic tree analysis, Histoplasma capsulatum var. Capsulatum (Hcc) was the main responsible pathogen, rarely reported in bone lesions. The patient underwent spinal surgery and was successfully treated with liposomal amphotericin B and itraconazole. Based on the diagnosis and treatment of this case, we discuss the epidemiologic status, clinical presentations, diagnostic criteria, and treatment guidelines of histoplasmosis to provide additional information about this disease. mNGS is utilized in this case, and it appears to be a reliable method for early and accurate diagnosis of this disease.

The Nairobi Declaration 2023: A commitment to address deadly yet neglected fungal diseases in Africa

On May 30th and 31st, 2023, delegates representing various African subregions, together with global representatives from the International Society of Human and Animal Mycology (ISHAM), the European Confederation of Medical Mycology (ECMM), the United States Centre for Disease Control and Prevention (CDC), and Global Action for Fungal Infections (GAFFI), convened in Nairobi, Kenya under the aegis of the Pan African Mycology Working Group, a working group of ISHAM. The meeting objectives were, amongst others, to deliberate on a continental response to the World Health Organisation Fungal Priority Pathogen List and facilitate interaction between global and regional leaders. Country delegates and international speakers addressed Africa's fungal disease burden; capacity for diagnosis and management; ongoing surveillance; knowledge gaps and trends in invasive fungal diseases such as Candida auris, mucormycosis, aspergillosis, and Acquired Immune Deficiency Syndrome (AIDS)-related mycoses; and current laboratory practice. During the technical sessions, expert panels deliberated on establishing and financing of national/regional surveillance networks for mycoses; establishing and sustaining African-led collaborations; expanding on existing laboratory and point-of-care diagnostic capacity as well as planning a mycology reference laboratory service and network in Africa. The meeting also highlighted successful African-led collaborations, capacity building, and clinical trial initiatives. The meeting conclusions informed the resolutions of the Nairobi Declaration calling for improved awareness; strong collaborations between clinical and laboratory teams across Africa; improved fungal disease surveillance within the continent; access to antifungals and diagnostics; and leveraging qualified human resources for mycology present within and outside Africa to facilitate trainings, collaborations, and exchanges.

Phenotypic characterization of cryptic species in the fungal pathogen Histoplasma

Histoplasmosis is an endemic mycosis that often presents as a respiratory infection in immunocompromised patients. Hundreds of thousands of new infections are reported annually around the world. The etiological agent of the disease, Histoplasma, is a dimorphic fungus commonly found in the soil where it grows as mycelia. Humans can become infected by Histoplasma through inhalation of its spores (conidia) or mycelial particles. The fungi transitions into the yeast phase in the lungs at 37°C. Once in the lungs, yeast cells reside and proliferate inside alveolar macrophages. We have previously described that Histoplasma is composed of at least five cryptic species that differ genetically, and assigned new names to the lineages. Here we evaluated multiple phenotypic characteristics of 12 strains from five phylogenetic species of Histoplasma to identify phenotypic traits that differentiate between these species: H. capsulatum sensu stricto, H. ohiense, H. mississippiense, H. suramericanum, and an African lineage. We report diagnostic traits for two species. The other three species can be identified by a combination of traits. Our results suggest that 1) there are significant phenotypic differences among the cryptic species of Histoplasma, and 2) that those differences can be used to positively distinguish those species in a clinical setting and for further study of the evolution of this fungal pathogen.

Design of a Multi-Epitope Vaccine against Histoplasma capsulatum through Immunoinformatics Approaches

Histoplasmosis is a widespread systemic disease caused by Histoplasma capsulatum, prevalent in the Americas. Despite its significant morbidity and mortality rates, no vaccines are currently available. Previously, five vaccine targets and specific epitopes for H. capsulatum were identified. Immunoinformatics has emerged as a novel approach for determining the main immunogenic components of antigens through in silico methods. Therefore, we predicted the main helper and cytotoxic T lymphocytes and B-cell epitopes for these targets to create a potential multi-epitope vaccine known as HistoVAC-TSFM. A total of 38 epitopes were found: 23 common to CTL and B-cell responses, 11 linked to HTL and B cells, and 4 previously validated epitopes associated with the B subunit of cholera toxin, a potent adjuvant. In silico evaluations confirmed the stability, non-toxicity, non-allergenicity, and non-homology of these vaccines with the host. Notably, the vaccine exhibited the potential to trigger both innate and adaptive immune responses, likely involving the TLR4 pathway, as supported by 3D modeling and molecular docking. The designed HistoVAC-TSFM appears promising against Histoplasma, with the ability to induce important cytokines, such as IFN-γ, TNF-α, IL17, and IL6. Future studies could be carried out to test the vaccine's efficacy in in vivo models.

Factors influencing histoplasmosis incidence in multidrug-resistant pulmonary tuberculosis patients: A cross-sectional study in Indonesia

Histoplasmosis is an infectious disease caused by the dimorphic fungus Histoplasma capsulatum, which in chronic conditions, is generally difficult to distinguish from pulmonary tuberculosis (TB) based on its clinical appearance; therefore, diagnostic errors could occur. Meanwhile, the prevalence of multidrug-resistant pulmonary TB (MDR-TB) in Indonesia remains high. Study determining the incidence of histoplasmosis in MDR-TB is unavailable worldwide. The aim of this study was to determine the risk factors of histoplasmosis incidence in MDR-TB patients in Indonesia. A cross-sectional was conducted at H. Adam Malik General Hospital, Medan, Indonesia and the ELISA platform (semi-quantitative) was used to detect histoplasma antibodies. Factors associated with histoplasmosis incidence among MDR-TB were determined using a Chi-squared test. A total of 50 MDR-TB patients were included this study of which 14 of them (28%) had histoplasmosis. The majority of histoplasmosis occurred in males, in MDR-TB patients with a history of TB treatment and among who had chest x-rays with far-advanced lesions. However, statistical analyses indicated none of those factors (sex, TB treatment history, status of the lung) as well as age group, acid-fast bacillus result, Mycobacterium tuberculosis culture result, having pet, living in damp house, working in the field or plantation, having HIV infection and smoking status were associated with histoplasmosis incidence. This study highlights that the incidence of histoplasmosis is relatively high and therefore further studies are important to be conducted in Indonesia that has a high MDR-TB cases.

Fungal diseases in Africa: Closing the gaps in diagnosis and treatment through implementation research and advocacy

Fungal diseases impose an escalating burden on public health in Africa, exacerbated by issues such as delayed diagnosis, inadequate therapy, and limited access to healthcare resources, resulting in significant morbidity and mortality. Effectively tackling these challenges demands a comprehensive approach encompassing research, training, and advocacy initiatives. Recent clinical mycology surveys conducted by Global Action for Fungal Infection (GAFFI) and the European Confederation of Medical Mycology/International Society for Human and Animal Mycology (ECMM/ISHAM) have underscored gaps in fungal diagnostics and the availability and accessibility of antifungal therapy in Africa. The World Health Organization (WHO) Fungal Priority Pathogens List (FPPL) identifies fungi of critical or high importance to human health, providing a roadmap for action and highlighting the urgent need for prioritizing fungal diseases and developing targeted interventions within the African context. To enhance diagnosis and treatment, it is imperative to invest in comprehensive training programs for healthcare workers across all levels and disciplines. Equipping them with the necessary knowledge and skills will facilitate early detection, accurate diagnosis, and appropriate management of fungal infections. Moreover, implementation science research in medical mycology assumes a pivotal role in bridging the gap between knowledge and practice. By identifying the barriers and facilitators that influence the adoption of diagnostic techniques and public health interventions, tailored strategies can be formulated to improve their implementation within healthcare settings. Advocacy plays a critical role in raising awareness regarding the profound impact of fungal diseases on public health in Africa. Engaging policymakers, healthcare providers, researchers, industry experts and communities underscore the importance of addressing these diseases and galvanize efforts for change. Substantial investment in surveillance, research and development specifically focused on fungal diseases is indispensable for advancing our understanding of local epidemiology, developing effective interventions, and ultimately improving patient outcomes. In conclusion, closing the gaps in diagnosing and treating fungal diseases in Africa demands concerted research and advocacy initiatives to ensure better healthcare delivery, reduced mortality rates, and improved public health outcomes.

Histoplasma Seropositivity in TB Patients in The Gambia: Evidence to Drive Research on a High-Priority Fungal Pathogen

Background

Inclusion of Histoplasma in the World Health Organization's first Fungal Priority Pathogens List under "high-priority" fungal species highlights the need for robust surveillance of Histoplasma spp. in endemic and underrepresented regions. Despite increasing reports of histoplasmosis in Africa, data on the burden of this fungal disease are sparse in The Gambia. This baseline study examined the human seroprevalence of anti-Histoplasma antibody in a TB patient group in The Gambia, explored associations between seropositivity and demographic and clinical variables, and proposes future research directions.

Methods

Biobanked plasma samples were selected from active TB cases with variable HIV infection status. Latex agglutination tests were performed on samples from 52 study participants to detect the presence of anti-Histoplasma antibodies. Potential risk factors for Histoplasma exposure were explored using logistic regression analysis.

Results

The sample seroprevalence of anti-Histoplasma antibody was 28.8% (n = 15/52; 95% CI, 17.1%-43.1%). Multivariable logistic regression analysis identified a statistically significant association between Histoplasma seropositivity and age (odds ratio, 0.91; 95% CI, 0.84-0.98; P = .008).

Conclusions

This baseline study provides evidence of Histoplasma seropositivity in TB patients in The Gambia and explores risk factors for exposure. The small sample size and use of the LAT in TB and HIV-positive patient groups are significant study limitations. Future research directions are proposed to ascertain the burden of Histoplasma in general and patient populations and explore the context-specific risk factors for exposure and infection in The Gambia.

The seroprevalence of anti-Histoplasma capsulatum IgG antibody among pulmonary tuberculosis patients in seven referral tuberculosis hospitals in Indonesia

BACKGROUND

Histoplasma capsulatum exposure is rarely suspected in Indonesia. Pulmonary histoplasmosis can occur simultaneously with pulmonary tuberculosis (TB) or as an alternative diagnosis in clinically-diagnosed TB patients with no microbiological evidence of TB. This study aimed to determine the seroprevalence of anti-H. capsulatum IgG antibody among pulmonary TB patients.

METHODOLOGY

This was a sub-study of 306 participants from a prospective cohort pulmonary TB study conducted at seven TB referral hospitals in Indonesia. The study population was presumptive pulmonary TB adult patients who underwent microbiological TB examinations and were categorized as drug-sensitive (DS), drug-resistant (DR), and clinically-diagnosed TB. Anti-H. capsulatum IgG antibody levels at baseline were measured using MVista Histoplasma Ab enzyme immunoassays. Data were summarized using descriptive statistics. Bivariate and multivariate logistic regression analysis were performed to assess factors associated with anti-H. capsulatum IgG antibody positive result.

RESULTS

12.7% (39/306) of pulmonary TB patients were positive for anti-H. capsulatum IgG antibodies (DR-TB patients (15.9%, 18/114), DS-TB (13.0%, 15/115), and clinically-diagnosed TB (7.8%, 6/77)). The median unit value of anti-H. capsulatum IgG antibody for all positive samples was 15.7 (IQR 10.2-28.9) EU. This median unit value was higher in clinically-diagnosed TB patients compared to DS-TB or DR-TB patients (38.1 (IQR 25.6-46.6) EU, 19.7 (IQR 12.3-28.9) EU, and 10.9 (IQR 9.2-15.4), respectively). There were 10 patients (3.3%) with anti-H. capsulatum IgG antibody levels above 30 EU. Factors associated with the anti-H. capsulatum IgG antibody positive result were malignancies (OR 4.88, 95% CI 1.09-21.69, p = 0.037) and cavitary lesions (OR 2.27, 95% CI 1.09-4.70, p = 0.028).

CONCLUSIONS

Our results provide evidence of exposure to H. capsulatum among pulmonary TB patients in Indonesia. Further studies are needed to provide a comprehensive picture of this fungal disease in other populations and regions to enhance awareness among clinicians and public health officials.

Acute pulmonary histoplasmosis: a case series from an outbreak in Southeastern Brazil

Histoplasmosis is a systemic mycosis prevalent in the Americas. Humans become infected via the respiratory route by inhaling aerosols from soil contaminated with bird and bat excretions. Acute pulmonary histoplasmosis is usually asymptomatic and is more often a self-limiting illness. We report a series of seven acute pulmonary cases in adults during an outbreak in Nova Friburgo city, Rio de Janeiro State, Brazil, in a group of volunteers who were cleaning an old, abandoned house without using personal protective equipment. The patients had a favorable evolution after suitable treatment, but all required hospitalization.

Investigating and combatting the key drivers of viral zoonoses in Africa: an analysis of eight epidemics

Investigating the interplay of factors that result in a viral zoonotic outbreak is difficult, though it is increasingly important. As anthropogenic influences shift the delicate balance of ecosystems, new zoonoses emerge in humans. Sub-Saharan Africa is a notable hotspot for zoonotic disease due to abundant competent mammalian reservoir hosts. Furthermore, poverty, corruption, and an overreliance on natural resources play considerable roles in depleting biological resources, exacerbating the population's susceptibility. Unsurprisingly, viral zoonoses have emerged in Africa, including HIV/AIDS, Ebola, Avian influenza, Lassa fever, Zika, and Monkeypox. These diseases are among the principal causes of death in endemic areas. Though typically distinct in their manifestations, viral zoonoses are connected by underlying, definitive factors. This review summarises vital findings on viral zoonoses in Africa using nine notable case studies as a benchmark for future studies. We discuss the importance of ecological recuperation and protection as a central strategy to control zoonotic diseases. Emphasis was made on moderating key drivers of zoonotic diseases to forestall future pandemics. This is in conjunction with attempts to redirect efforts from reactive to pre-emptive through a multidisciplinary "one health" approach.

Prevalence of Histoplasma Antigenuria among Outpatient Cohort with Advanced HIV in Kampala, Uganda

In sub-Saharan Africa, an estimated 25% of people with HIV present with advanced HIV and are at high risk of opportunistic infections. Whereas histoplasmosis has occasionally been seen in Uganda, the understanding of the local risk of acute infection is limited. We sought to determine the prevalence of Histoplasma antigenuria using an enzyme immunoassay (EIA, clarus Histoplasma GM EIA, IMMY; Norman, OK, USA) in a cohort of outpatients with advanced HIV disease in Kampala, Uganda. Among the persons with positive urine Histoplasma antigen tests, we assessed their clinical presentation and outcomes. The EIA was run on stored urine samples as per the manufacturer's instructions. Specimens ≥1 EIA units were considered positive. Among the 388 tested urine samples, 4 (1.2%) were positive for Histoplasma antigen. The histoplasmosis prevalence among participants with a CD4 < 100 cells/mcL was 2.5% (4/158). Three of the four participants with a positive Histoplasma antigen test reported systemic symptoms consistent with histoplasmosis. All four participants had a positive urine lipoarabinomannan test and were treated for tuberculosis. By the four-week follow-up visit, all participants were clinically improved, alive, and in care without antifungal therapy. In advanced HIV, the clinical presentations of tuberculosis and histoplasmosis overlap. The value of histoplasmosis screening and pre-emptive treatment is an area of future research.

Love in the time of climate change: A review of sexual reproduction in the order Onygenales

Life-threatening infections caused by fungi in the order Onygenales have been rising over the last few decades. Increasing global temperature due to anthropogenic climate change is one potential abiotic selection pressure that may explain the increase in infections. The generation of genetically novel offspring with novel phenotypes through the process of sexual recombination could allow fungi to adapt to changing climate conditions. The basic structures associated with sexual reproduction have been identified in Histoplasma, Blastomyces, Malbranchea, and Brunneospora. However, for Coccidioides and Paracoccidioides, the actual structural identification of these processes has yet to be identified despite having genetic evidence that suggests sexual recombination is occurring in these organisms. This review highlights the importance of assessing sexual recombination in the order Onygenales as a means of understanding the mechanisms these organisms might employ to enhance fitness in the face of a changing climate and provides details regarding the known reproductive mechanisms in the Onygenales.

Evidence of Histoplasma capsulatum seropositivity and exploration of risk factors for exposure in Busia county, western Kenya: Analysis of the PAZ dataset

BACKGROUND

Despite recognition of histoplasmosis as a disease of national public health concern in Kenya, the burden of Histoplasma capsulatum in the general population remains unknown. This study examined the human seroprevalence of anti-Histoplasma antibody and explored associations between seropositivity and demographic and environmental variables, in Busia county, western Kenya.

METHODOLOGY

Biobanked serum samples and associated data, from a previous cross-sectional survey, were examined. Latex agglutination tests to detect the presence of anti-Histoplasma antibody were performed on serum samples from 670 survey respondents, representing 178 households within 102 sub-locations. Potential epidemiologic risk factors for H. capsulatum exposure were explored using multi-level multivariable logistic regression analysis with household and sub-location included as random effects.

PRINCIPAL FINDINGS

The apparent sample seroprevalence of anti-Histoplasma antibody was 15.5% (n = 104/670, 95% Confidence Interval (CI) 12.9-18.5%). A multivariable logistic regression model identified increased odds of H. capsulatum seropositivity in respondents reporting rats within the household within the previous 12 months (OR = 2.99 90% CI 1.04-8.55, p = 0.04). Compared to respondents aged 25-34 years, the odds of seropositivity were higher in respondents aged 15-24 years (OR = 2.70 90% CI 1.04-6.97, p = 0.04).

CONCLUSIONS

The seroprevalence result provides a baseline for sample size approximations for future epidemiologic studies of the burden of H. capsulatum exposure in Busia county. The final model explored theoretically plausible risk factors for H. capsulatum exposure in the region. A number of factors may contribute to the complex epidemiological picture impacting H. capsulatum exposure status at the human-animal-environment interface in western Kenya. Focussed H. capsulatum research is warranted to determine the contextual significance of identified associations, and in representative sample populations.

Approach to the diagnosis of invasive fungal infections of the respiratory tract in the immunocompromised host

PURPOSE OF REVIEW

The burden of invasive fungal infection is increasing worldwide, largely due to a growing population at-risk. Most serious human fungal pathogens enter the host via the respiratory tract. Early identification and treatment of invasive fungal respiratory infections (IFRIs) in the immunocompromised host saves lives. However, their accurate diagnosis is a difficult challenge for clinicians and mortality remains high.

RECENT FINDINGS

This article reviews IFRIs, focussing on host susceptibility factors, clinical presentation, and mycological diagnosis. Several new diagnostic tools are coming of age including molecular diagnostics and point-of-care antigen tests. As diagnosis of IFRI relies heavily on invasive procedures like bronchoalveolar lavage and lung biopsy, several novel noninvasive diagnostic techniques are in development, such as metagenomics, 'volatilomics' and advanced imaging technologies.

SUMMARY

Where IFRI cannot be proven, clinicians must employ a 'weights-of-evidence' approach to evaluate host factors, clinical and mycological data. Implementation studies are needed to understand how new diagnostic tools can be best applied within clinical pathways. Differentiating invasive infection from colonization and identifying antifungal resistance remain key challenges. As our diagnostic arsenal expands, centralized clinical mycology laboratories and efforts to ensure access to new diagnostics in low-resource settings will become increasingly important.

Gastrointestinal Histoplasmosis: A Descriptive Review, 2001-2021

Gastrointestinal histoplasmosis (GIH) is infrequently described in people without underlying HIV infection. We aimed to compare the clinical presentation of GIH in people with and without HIV infection. We conducted a literature search of published cases of GIH from 2001-2021 and found 212 cases. Of these, 142 (67.0%) were male, and 124 (58.5%) had HIV infection. Most cases were from North America (n = 88, 41.5%) and South America (n = 79, 37.3%). Of the 212 cases, 123 (58.0%) were included in both clinical and pathological analyses. The remainder were excluded as details about clinical and pathological findings were not available. Of the 123 cases, 41 had HIV infection while 82 were without HIV infection. The diagnosis was predominantly by histopathology (n = 109, 88.6%). A significant proportion of people with HIV infection had abdominal pain as the most predominant symptom of GIH compared to those without HIV infection (65.9% versus 41.9%, p < 0.05). The colon was the most affected site with a slightly higher proportion in those with HIV infection compared with cases without HIV infection (46.3% versus 42.7%). The commonest pathologic findings were caecal and ileal ulcers. Caecal ulcers were significantly more frequent in cases with HIV infection compared to those without HIV (32.1% versus 7.1%, p < 0.05). Despite being more common in people with HIV infection, GIH also affects people without HIV infection with similar clinical presentations.

Emerging and re-emerging fungal threats in Africa

The emergence of deadly fungal infections in Africa is primarily driven by a disproportionately high burden of human immunodeficiency virus (HIV) infections, lack of access to quality health care, and the unavailability of effective antifungal drugs. Immunocompromised people in Africa are therefore at high risk of infection from opportunistic fungal pathogens such as Cryptococcus neoformans and Pneumocystis jirovecii, which are associated with high morbidity, mortality, and related socioeconomic impacts. Other emerging fungal threats include Emergomyces spp., Histoplasma spp., Blastomyces spp., and healthcare-associated multi-drug resistant Candida auris. Socioeconomic development and the Covid-19 pandemic may influence shifts in epidemiology of invasive fungal diseases on the continent. This review discusses the epidemiology, clinical manifestations, and current management strategies available for these emerging fungal diseases in Africa. We also discuss gaps in knowledge, policy, and research to inform future efforts at managing these fungal threats.

In Vitro Study of the Leishmanicidal Activity of Perovskia Abrotanoides Terpenoid-Rich Fractions Against Leishmania Major (MRHO/IR/75/ER)

Background

Cutaneous leishmaniasis (CL) is an ulcerative skin disease caused by some species of the genus Leishmania. Evidence shows that Perovskia abrotanoides is an important herbal medicine against Leishmania. This study was conducted to investigate the killing effect of terpenoid-rich fractions on promastigotes of L. major (MRHO/IR/75/ER).

Material and Method

The eluates of reverse phased medium pressure liquid chromatography (RP-MPLC) of the extract were subjected to thin-layer chromatography (TLC) and categorized into six final fractions. Primary proton nuclear magnetic resonance (H-NMR) spectroscopy confirmed fractions' nature. Fractions 4, 5, and 6 (F4, F5, F6) were identified as terpenoid-rich content. Two concentrations of 50 and 100 μg/ml were prepared to test leishmanicidal activity. Followed by treating promastigotes of L. major by the fractions in incubation times of 12, 24, and 48 hours, their viability was determined using a cell proliferation MTS ((3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay.

Result

F4, F5, and F6 showed significant killing activity on promastigotes of L. major in a concentration-dependent manner. The viability of promastigotes was significantly reduced at a concentration of 100 μg/ml compared to 50 μg/ml (P-value <0.05). Also, over time a significant decreasing trend in the viability of promastigotes confirmed the time-dependent manner of the fractions (P-value <0.01). Furthermore, F5 had the highest leishmanicidal activity at the first incubation time compared with other fractions.

Conclusion

Terpenoid-rich fractions of the P. abrotanoides have a leishmanicidal activity that depends on time and concentration. Among them, F5 has the highest potency that may contain potent terpenoid constituents.

Current epidemiology of histoplasmosis in Nigeria: A systematic review and meta-analysis

Introduction

Histoplasmosis commonly occurs in the advanced HIV disease population and also in immunocompetent individuals. Previous reviews and recent studies highlight several cases of histoplasmosis reported in Nigeria. We aimed to describe the current epidemiology of histoplasmosis in Nigeria and the need for active surveillance in the at-risk populations.

Methods

Literature searches for all publications on histoplasmosis in Nigeria were performed using online databases including Google scholar, PubMed and African Journal online. The following search terms: 'histoplasmosis' and 'Nigeria', AND/OR 'Histoplasma and Nigeria' were used. No limitations on the date or other search criteria were applied, to avoid the exclusion of articles on histoplasmosis in Nigeria. All publications on histoplasmosis outside Nigeria were excluded.

Results

Our review identified a total of 231 cases of histoplasmosis reported from Nigeria: 128 were from individual case reports and case series while 103 were cases from two observational studies. Of the 231 cases, 97 (42.0%) were from South West Nigeria, 66 (28.6%) were from South-South Nigeria, 24 (10.4%) were from North West, 22 (9.5%) from North Central Nigeria, 17 (7.4%) from South East Nigeria and 5 (2.2%) from the North East. Based on Nigeria's current population size of 216,953,585 the burden of histoplasmosis per 100,000 inhabitants was estimated to be 0.1%. The sheer number of cases detected in recent observational studies compared with individual case reports and series reported over a longer duration of 6 decades suggests gross under-reporting of histoplasmosis in Nigeria.

Conclusion

Histoplasmosis is not an uncommon clinical entity in Nigeria. Histoplasmosis case finding should be improved by training and retraining healthcare professionals and providing much-needed diagnostic capacity and infrastructure across health facilities in Nigeria.

Striving towards access to essential medicines for human and animal health; a situational analysis of access to and use of antifungal medications for histoplasmosis in Ethiopia

Antifungal medications are vital in combatting fungal diseases that affect over a billion people annually. Antifungal medications for people and equids are scarce in Ethiopia, where lack of resources to treat fungal infection, in particular histoplasmosis, is a major health challenge. Histoplasmosis is endemic within the equine population in Ethiopia, where it is estimated that one in five horses are infected. This disease has far reaching impacts on equine welfare and the socio-economic wellbeing of families. The burden of histoplasmosis in people in Ethiopia is currently unknown, representing a blind spot in public health surveillance. Previous research has identified contact with wildlife, and domestic animal species as possible transmission pathways for histoplasmosis however, questions remain about the role of equids in human histoplasmosis. Given the close proximity of people and animals in this setting, the high level of endemic disease among equids, and the common sources of anti-fungals in Ethiopia, our study adopted a One-Health approach to examine how systemic issues affect access to, and use of antifungals to treat histoplasmosis among people and equids. A qualitative study was conducted in 6 urban regions of Oromia, Ethiopia in December 2018, incorporating semi-structured face-to-face interviews and focus group discussions. Twenty-seven individual interviews were held with doctors (n = 7), pharmacists (n = 12), veterinarians (n = 5), para-veterinarians (n = 2) and an equid owner (n = 1). Eleven focus groups were conducted with equid owners (n = 42), 3 with veterinarians (n = 6), 1 with para-veterinarians (n = 2) and 1 with pharmacists (n = 2). Transcripts were analysed using thematic analysis, and dimensions of key themes conceptualised and compared. Two overarching themes namely, 'Structural', and 'Human factors', summarised the main limitations to access to antifungal medications. 'Structural factors' included the national reliance on importation of medicines or pharmaceutical ingredients, inaccurate demand forecasting due to poor recording of the shortfall within the pharmaceutical supply chain, deficiencies in diagnostic capacity for fungal disease and, a healthcare system funded with a significant component of out-of-pocket expenditure. 'Human factors' that influenced access to antifungals included the perception of the expense of antifungals compared with competing needs such as food and education, the social stigma attached to histoplasmosis that could lead to delays in treatment seeking and, readily available home remedies or alternative treatment options. Furthermore, it was reported that trust in healthcare and veterinary provisions was undermined by a perceived lack of efficacious medications. Access to antifungals remains an urgent public health and animal welfare concern in Ethiopia. Key points within the supply and distribution chain that affect access to anti-fungals are identified, and policies that facilitate anti-fungal procurement and distribution should be reviewed. This paper highlights the structural, socio-economic and cultural factors influencing the management of infection with histoplasmosis, including how it is understood, identified and treated. This study identifies areas where further cross-sectorial work is needed to address these factors to improve disease control and clinical outcomes observed in human and animal histoplasmosis within Ethiopia.

Osteoarticular Mycoses

Osteoarticular mycoses are chronic debilitating infections that require extended courses of antifungal therapy and may warrant expert surgical intervention. As there has been no comprehensive review of these diseases, the International Consortium for Osteoarticular Mycoses prepared a definitive treatise for this important class of infections. Among the etiologies of osteoarticular mycoses are Candida spp., Aspergillus spp., Mucorales, dematiaceous fungi, non-Aspergillus hyaline molds, and endemic mycoses, including those caused by Histoplasma capsulatum, Blastomyces dermatitidis, and Coccidioides species. This review analyzes the history, epidemiology, pathogenesis, clinical manifestations, diagnostic approaches, inflammatory biomarkers, diagnostic imaging modalities, treatments, and outcomes of osteomyelitis and septic arthritis caused by these organisms. Candida osteomyelitis and Candida arthritis are associated with greater events of hematogenous dissemination than those of most other osteoarticular mycoses. Traumatic inoculation is more commonly associated with osteoarticular mycoses caused by Aspergillus and non-Aspergillus molds. Synovial fluid cultures are highly sensitive in the detection of Candida and Aspergillus arthritis. Relapsed infection, particularly in Candida arthritis, may develop in relation to an inadequate duration of therapy. Overall mortality reflects survival from disseminated infection and underlying host factors.

Diagnostic capacity for invasive fungal infections in advanced HIV disease in Africa: a continent-wide survey

BACKGROUND

Fungal infections are common causes of death and morbidity in those with advanced HIV infection. Data on access to diagnostic tests in Africa are scarce. We aimed to evaluate the diagnostic capacity for invasive fungal infections in advanced HIV disease in Africa.

METHODS

We did a continent-wide survey by collecting data from 48 of 49 target countries across Africa with a population of more than 1 million; for Lesotho, only information on the provision of cryptococcal antigen testing was obtained. This survey covered 99·65% of the African population. We did the survey in six stages: first, questionnaire development, adaptation, and improvement; second, questionnaire completion by in-country respondents; third, questionnaire review and data analysis followed by video conference calls with respondents; fourth, external validation from public or private sources; fifth, country validation by video conference with senior figures in the Ministry of Health; and sixth, through five regional webinars led by the Africa Centres for Disease Control and Prevention with individual country profiles exchanged by email. Data was compiled and visualised using the Quantum Geographic Information System software and Natural Earth vectors to design maps showing access.

FINDINGS

Data were collected between Oct 1, 2020, and Oct 31, 2022 in the 48 target countries. We found that cryptococcal antigen testing is frequently accessible to 358·39 million (25·5%) people in 14 African countries. Over 1031·49 million (73·3%) of 1·4 billion African people have access to a lumbar puncture. India ink microscopy is frequently accessible to 471·03 million (33·5%) people in 23 African countries. About 1041·62 million (74·0%) and 1105·11 million (78·5%) people in Africa do not have access to histoplasmosis and Pneumocystis pneumonia diagnostics in either private or public facilities, respectively. Fungal culture is available in 41 countries covering a population of 1·289 billion (94%) people in Africa. MRI is routinely accessible to 453·59 million (32·2%) people in Africa and occasionally to 390·58 million (27·8%) people. There was a moderate correlation between antiretroviral therapy usage and external expenditure on HIV care (R²=0·42) but almost none between external expenditure and AIDS death rate (R²=0·18), when analysed for 40 African countries.

INTERPRETATION

This survey highlights the enormous challenges in the diagnosis of HIV-associated Pneumocystis pneumonia, cryptococcal disease, histoplasmosis, and other fungal infections in Africa. Urgent political and global health leadership could improve the diagnosis of fungal infections in Africa, reducing avoidable deaths.

FUNDING

Global Action For Fungal Infections.

Advancing disease genomics beyond COVID-19 and reducing health disparities: what does the future hold for Africa?

The COVID-19 pandemic has ushered in high-throughput sequencing technology as an essential public health tool. Scaling up and operationalizing genomics in Africa is crucial as enhanced capacity for genome sequencing could address key health problems relevant to African populations. High-quality genomics research can be leveraged to improve diagnosis, understand the aetiology of unexplained illnesses, improve surveillance of infectious diseases and inform efficient control and therapeutic methods of known, rare and emerging infectious diseases. Achieving these within Africa requires strong commitment from stakeholders. A roadmap is needed to guide training of scientists, infrastructural development, research funding, international collaboration as well as promote public–private partnerships. Although the COVID-19 pandemic has significantly boosted genomics capacity in Africa, the continent still lags other regions. Here, we highlighted key initiatives in genomics research and efforts to address health challenges facing the diverse and fast-growing populations on the continent. We explore the scalability of genomic tools and techniques to tackle a broader range of infectious diseases in Africa, a continent that desperately requires a boost from genomic science.

Invasive Fungal Diseases in Africa: A Critical Literature Review

Invasive fungal diseases (IFDs) are of huge concern in resource-limited settings, particularly in Africa, due to the unavailability of diagnostic armamentarium for IFDs, thus making definitive diagnosis challenging. IFDs have non-specific systemic manifestations overlapping with more frequent illnesses, such as tuberculosis, HIV, and HIV-related opportunistic infections and malignancies. Consequently, IFDs are often undiagnosed or misdiagnosed. We critically reviewed the available literature on IFDs in Africa to provide a better understanding of their epidemiology, disease burden to guide future research and interventions. Cryptococcosis is the most encountered IFD in Africa, accounting for most of the HIV-related deaths in sub-Saharan Africa. Invasive aspergillosis, though somewhat underdiagnosed and/or misdiagnosed as tuberculosis, is increasingly being reported with a similar predilection towards people living with HIV. More cases of histoplasmosis are also being reported with recent epidemiological studies, particularly from Western Africa, showing high prevalence rates amongst presumptive tuberculosis patients and patients living with HIV. The burden of pneumocystis pneumonia has reduced significantly probably due to increased uptake of anti-retroviral therapy among people living with HIV both in Africa, and globally. Mucormycosis, talaromycosis, emergomycosis, blastomycosis, and coccidiomycosis have also been reported but with very few studies from the literature. The emergence of resistance to most of the available antifungal drugs in Africa is yet of huge concern as reported in other regions. IFDs in Africa is much more common than it appears and contributes significantly to morbidity and mortality. Huge investment is needed to drive awareness and fungi related research especially in diagnostics and antifungal therapy.

Prevalence of Histoplasmosis among Persons with Advanced HIV Disease, Nigeria

We sought to determine the prevalence of probable disseminated histoplasmosis among advanced HIV disease (AHD) patients in Nigeria. We conducted a cross-sectional study in 10 sites across 5 of 6 geopolitical zones in Nigeria. We identified patients with urinary samples containing CD4 cell counts <200 cells/mm³ or World Health Organization stage 3 or 4 disease who also had >2 clinical features of disseminated histoplasmosis, and we tested them for Histoplasma antigen using a Histoplasma enzyme immune assay. Of 988 participants we recruited, 76 (7.7%) were antigen-positive. The 76 Histoplasma antigen-positive participants had significantly lower (p = 0.03) CD4 counts; 9 (11.8%) were also co-infected with tuberculosis. Most antigen-positive participants (50/76; 65.8%; p = 0.015) had previously received antiretroviral treatment; 26/76 (34.2%) had not. Because histoplasmosis is often a hidden disease among AHD patients in Nigeria, Histoplasma antigen testing should be required in the AHD package of care.

Recent advances and challenges in the early diagnosis and management of invasive fungal infections in Africa

Invasive fungal infections are a serious concern globally, especially in African settings which are typified by poorly funded and fragile healthcare systems. Low performance diagnostics, limited therapeutics and poor societal awareness of invasive fungal infections are some of the perennial challenges which have contributed to the unacceptably high death rates from these serious infections. However, recent advances have been recorded in fungal diagnostics and therapeutics development. Research into the development of vaccines to prevent fungal disease is beginning to yield promising results. Here we highlight key successes recorded and gaps in this journey and argue that national governments and relevant stakeholders need to do more to prioritise invasive fungal infections. Pragmatic and context-specific measures are proposed to mitigate the peculiar challenges Africa faces in tackling invasive fungal infections.

Pathogenicity & Virulence of Histoplasma capsulatum - a multifaceted organism adapted to intracellular environments

Histoplasmosis is a systemic mycosis caused by the thermally dimorphic fungus Histoplasma capsulatum. Although healthy individuals can develop histoplasmosis, the disease is particularly life-threatening in immunocompromised patients, with a wide range of clinical manifestations depending on the inoculum and virulence of the infecting strain. In this review, we discuss the established virulence factors and pathogenesis traits that make H. capsulatum highly adapted to a wide variety of hosts, including mammals. Understanding and integrating these mechanisms is a key step towards devising new preventative and therapeutic interventions.

Development of an Interferon-Gamma Release Assay (IGRA) to Aid Diagnosis of Histoplasmosis

Establishing diagnosis of latent and active histoplasmosis is challenging. Interferon gamma-release assays (IGRAs) may provide evidence of latent and active infection. An enzyme-linked immunospot (ELISpot) assay was developed using yeast cell lysate (YCL) antigen prepared from a representative North American Histoplasma capsulatum strain. Assay parameters were optimized by measuring responses in healthy volunteers with and without Histoplasma infection. Assay performance as an aid for diagnosing histoplasmosis was assessed in a prospective cohort of 88 people with suspected or confirmed infection, and 44 healthy controls enrolled in two centers in North America (2013 to 2018). Antigen specificity of IFN-γ release was demonstrated using ELISpot and enzyme-linked immunosorbent assay (ELISA). Antigen-evoked, single-cell mRNA expression by memory T cells was shown using flow cytometry. The area under the receiver operating characteristic curve (AUC) was estimated at 0.89 (95% confidence interval [CI]: 78.5% to 99.9%). At optimal cutoff, sensitivity was 77.2% (95% CI: 54.6% to 92.2%) and specificity was 100% (95% CI: 89.7% to 100%). Sixteen of 44 healthy volunteers (36.4%) from a region of hyperendemicity had positive responses, suggesting detection of previously unrecognized (latent) infection. The ELISpot assay is sensitive and specific as an aid to diagnose H. capsulatum infection and disease, supporting proof of concept and further development.

Endemic mycoses in South Africa, 2010–2020: A decade-long description of laboratory-diagnosed cases and prospects for the future

Background

Emergomycosis, histoplasmosis, sporotrichosis and blastomycosis are endemic to southern Africa; the first two are AIDS-related mycoses. We described laboratory-diagnosed cases of endemic and imported mycoses in South Africa over a decade and discuss available diagnostic tools, reasons for the current under-estimation of cases and future strategies to improve case ascertainment.

Materials and methods

We analysed electronic pathology laboratory data from all public laboratories and one large private laboratory in South Africa from 2010–2020. Diagnostic specimens processed at the national mycology reference laboratory were also included. We classified cases as proven, probable and possible based on the method of identification.

Results

We identified 682 cases, of which 307 were proven, 279 were probable and 96 were possible. Of 307 culture-confirmed cases, 168 were identified by phenotypic methods plus sequencing, 128 by phenotypic methods alone and 11 by direct PCR. Of 279 probable cases, 176 had yeasts observed on histology, 100 had a positive Histoplasma antigen test and 3 a positive pan-dimorphic PCR test. All 96 possible cases had compatible clinical syndrome with inflammatory infiltrates on skin tissue histology. A majority of cases had an unspecified endemic mycosis (207/682, 30.4%), followed by sporotrichosis (170/682, 24.9%), emergomycosis (154/682, 22.6%), histoplasmosis (133/682, 19.5%), blastomycosis (14/682, 2.1%) and talaromycosis (4/682, 0.6%).

Conclusions

This study reports a relatively low number of cases over a decade considering an estimated large population at risk, suggesting that a substantial fraction of cases may remain undiagnosed. There is a need to increase awareness among healthcare workers and to develop rapid point-of-care diagnostic tools and make these widely accessible.

Emergomycosis, histoplasmosis, sporotrichosis and blastomycosis are serious fungal diseases which occur in southern Africa among people with either healthy or weakened immune systems. These fungal diseases may be missed because they mimic other diseases, occur together with other conditions that mask their presence or are simply not considered by healthcare workers. There are very few available simple diagnostic tests and most African countries do not conduct fungal disease surveillance. We described cases of these fungal diseases, which had been diagnosed in South African laboratories, from 2010–2020. We identified 682 cases, of which 307 were proven, 279 were probable and 96 were possible based on the available clinical and laboratory information. A majority of cases could not be allocated to one of the four disease types and were classified as unspecific endemic mycoses (30.4%). The remainder were sporotrichosis (24.9%), emergomycosis (22.3%), histoplasmosis (19.5%), blastomycosis (2.1%) and a travel-associated infection, talaromycosis (0.6%). We found relatively few cases considering the large population at risk. We believe that this could be due to the above-mentioned issues and insufficient expertise in diagnostic laboratories. There is a need to increase awareness among healthcare workers and to develop rapid point-of-care diagnostic tools and make these widely accessible.

Immunologic Diagnosis of Endemic Mycoses

The endemic mycoses blastomycosis, coccidioidomycosis, histoplasmosis, paracoccidioidomycosis, cryptococcosis, sporotrichosis, talaromycosis, adiaspiromycosis, and emergomycosis are mostly caused by geographically limited thermally dimorphic fungi (except for cryptococcosis), and their diagnoses can be challenging. Usual laboratory methods involved in endemic mycoses diagnosis include microscopic examination and culture of biological samples; however, serologic, histopathologic, and molecular techniques have been implemented in the last few years for the diagnosis of these mycoses since the recovery and identification of their etiologic agents is time-consuming and lacks in sensitivity. In this review, we focus on the immunologic diagnostic methods related to antibody and antigen detection since their evidence is presumptive diagnosis, and in some mycoses, such as cryptococcosis, it is definitive diagnosis.

Animal Histoplasmosis in Europe: Review of the Literature and Molecular Typing of the Etiological Agents

Histoplasmosis has been previously diagnosed in animals from Europe. The aim of this study is to review the literature on these reports, to analyze cases diagnosed at our laboratory (2000–2022) and to improve molecular typing of Histoplasma capsulatum directly from tissue to study the molecular epidemiology of Histoplasma capsulatum causing animal infections in Europe. Including 15 cases studied in our laboratory, we identified 39 cases of animal histoplasmosis between 1968 and 2022. They were diagnosed mostly in superficial tissue biopsies from cats and badgers from Central Europe. Using phylogenetic analyses of six partial genes, we were able to classify eight of the etiological agents as belonging to a highly supported lineage within the Eurasian clade. This study confirms the occurrence of autochthonous histoplasmosis in animals in Central Europe and proposes the addition of new loci to the MLST scheme to study the molecular epidemiology of histoplasmosis using either formalin-fixed paraffin-embedded tissue and fresh or cadaveric biopsies.

Prevalence of histoplasmosis and molecular characterization of Histoplasma in patients with presumptive pulmonary tuberculosis in Calabar, Nigeria

Background

Several case reports abound in literature about cases of histoplasmosis misdiagnosed as tuberculosis (TB). Nigeria is one of the highest TB-burdened countries, but data on histoplasmosis in Nigeria are sparse in the literature. The aim of this research was to investigate patients with presumptive pulmonary TB in Calabar, Nigeria, for histoplasmosis.

Methods

This was a descriptive cross-sectional study of 213 participants with presumptive diagnosis of pulmonary TB between April 2020 and March 2021. Urine samples were collected from selected patients for Histoplasma antigen test using enzyme immunoassay kits, while sputum samples were collected for GeneXpert test for confirmed diagnosis of TB and conventional polymerase chain reaction (PCR) for the diagnosis of histoplasmosis.

Results

Of the 213 participants enrolled into the study, 94 subjects (44.1%) were confirmed TB patients, 75 (35.2%) were human immunodeficiency virus (HIV) positive, 41 (19.2%) had advanced HIV disease (AHD), and 138 (64.8%) were HIV negative. Twenty-seven of the 213 participants were Histoplasma positive by antigen test and/or PCR, giving an overall prevalence rate of 12.7%. The prevalence of histoplasmosis among confirmed TB patients (7.4% [7/94]) was significantly lower than in unconfirmed TB patients (16.8% [20/119]) (P = .04). Participants on anti-TB therapy also had a significantly lower rate of histoplasmosis compared to those not on anti-TB drugs (P = .00006). The internal transcribed spacer (ITS) sequencing of the Histoplasma revealed a closely relatedness to Histoplasma capsulatum.

Conclusions

Histoplasmosis is not uncommon among presumptive TB patients. There should be proper microbiological investigation of patients presenting with symptoms suggestive of TB to exclude cases of histoplasmosis.

Cryptococcal and Histoplasma Antigen Screening among People With HIV in Ghana and Comparative Analysis of OIDx Histoplasma Lateral Flow Assay and IMMY Histoplasma Enzyme Immunoassay

Background

Cryptococcal meningitis (CM) and disseminated histoplasmosis (DH) are common in people with HIV (PWH) and diagnosed by detecting cryptococcal antigen (CrAg) and Histoplasma antigen (Histo Ag) respectively. In Ghana, CM and DH are rarely suspected by clinicians due to limited epidemiological data.

Methods

This study was conducted among PWH in Ghana who are unwell. Sociodemographic and clinical data were collected by questionnaire. Serum and/or urine were screened for CrAg and Histo Ag, using IMMY CrAg lateral flow assay (LFA) and IMMY Histoplasma enzyme immunoassay (EIA) kits, respectively, regardless of symptoms. Samples run with IMMY Histoplasma EIA were simultaneously run with OIDx Histoplasma LFA. Laboratory investigations were conducted by the research team while diagnosis incorporating clinical assessment, screening and confirmatory testing results and treatment decisions were made by the clinical team. Treatment and outcome information on CM and DH patients were evaluated.

Results

Overall, 150 participants were recruited. There were 73% (n = 109) females, and the age range was 18–62 years. The prevalence rates of CrAg and Histo Ag were 2.7% (4/150) and 4.7% (5/107), respectively. The OIDx Histoplasma LFA showed a high concordance (98.4%) with the IMMY Histoplasma EIA. All antigen-positive cases by standard tests were diagnosed with CM and DH. Antifungal treatment was given in five patients and follow-up revealed two deaths and three recoveries.

Conclusion

Histoplasmosis among PWH may be more common than previously anticipated and may be more frequent than cryptococcosis in Ghana. The performance of the OIDx Histoplasma LFA should be further explored.

Current situation of fungal diseases in Eritrea

The epidemiology of fungal infections in Eritrea is unknown. Most cases are under‐reported due to a lack of diagnostics. This study estimates the burden of serious fungal infections and highlights treatment and diagnostic gaps in the country. All publications related to fungal infections were identified by searches using PubMed/Medline and Google Scholar. Where no data were available, data from neighbouring countries, then sub‐Saharan African countries, then other parts of the world were considered for deriving estimates. The Eritrea population was 3,546,427 in 2020. In 2020, HIV/AIDS patients numbered 1400 and TB incidence were 2875. The five‐year adult prevalence of asthma (2016–2020) was 41,390, and the total prevalence estimate of chronic obstructive pulmonary disease (COPD) was 308,328. The annual incidence of cryptococcal meningitis and Pneumocystis jirovecii pneumonia in AIDS patients was estimated at 96 and 205 cases. Oesophageal candidiasis incidence is 715 HIV‐infected patients. Chronic pulmonary aspergillosis prevalence, including post‐tuberculosis cases, was estimated at 1399 (39/100,000). Fungal asthma has a prevalence of 1035 and 1366 in adults. The estimated prevalence of recurrent vulvovaginal candidiasis and tinea capitis is 59,391 and 342,585, respectively. There are no data on candidaemia, but it is estimated at 5/100,000 (177 cases annually). Invasive aspergillosis in leukaemia, lung cancer, COPD and HIV is estimated at 540 cases and fungal keratitis in 514 cases annually. Serious fungal infections are prevalent in Eritrea with approximately 408,164 people (11.5%) affected annually. Studies on fungal diseases to improve diagnosis and treatment are required with the implementation of a national surveillance program.

Challenges in Serologic Diagnostics of Neglected Human Systemic Mycoses: An Overview on Characterization of New Targets

Systemic mycoses have been viewed as neglected diseases and they are responsible for deaths and disabilities around the world. Rapid, low-cost, simple, highly-specific and sensitive diagnostic tests are critical components of patient care, disease control and active surveillance. However, the diagnosis of fungal infections represents a great challenge because of the decline in the expertise needed for identifying fungi, and a reduced number of instruments and assays specific to fungal identification. Unfortunately, time of diagnosis is one of the most important risk factors for mortality rates from many of the systemic mycoses. In addition, phenotypic and biochemical identification methods are often time-consuming, which has created an increasing demand for new methods of fungal identification. In this review, we discuss the current context of the diagnosis of the main systemic mycoses and propose alternative approaches for the identification of new targets for fungal pathogens, which can help in the development of new diagnostic tests.

Progressive disseminated histoplasmosis in HIV-positive patients

BACKGROUND

Histoplasmosis is the most common endemic mycosis among people living with advanced HIV infection.

PURPOSE

Describe general aspects and challenges of this disease and its association with HIV.

RESEARCH DESIGN

Review of literature.

STUDY SAMPLE

Articles found using different combinations of terms including "disseminated histoplasmosis" and AIDS/HIV or immunosuppression in PubMed, Scopus, WHO Global health library, and Scielo database.

ANALYSIS

We look for information on epidemiology, pathogenesis, diagnosis, and treatment of histoplasmosis in AIDS patients.

RESULTS

Histoplasmosis is caused by Histoplasma capsulatum, a dimorphic fungus encountered throughout the world, mainly in soil enriched with bat and bird excreta. Progressive disseminated histoplasmosis is the main presentation of this mycosis in people living with advanced HIV and is fatal if left untreated. Symptoms include a systemic disease characterized by fever, weight loss, night sweats, skin manifestations, hepatomegaly, splenomegaly, and septic shock. Diagnostic tests include culture, visualization of H. capsulatum by direct and histopathological examination, serology, antigen, molecular, and skin testing. Patients with disseminated disease require aggressive and prolonged treatment to eradicate the pathogen and include amphotericin B and itraconazole. In many low income countries of endemic regions, histoplasmosis in HIV-positive patients is often undiagnosed or misdiagnosed as another opportunistic infection, due to the similarity in clinical manifestations and to the paucity of better diagnostic tests.

CONCLUSION

Histoplasmosis remains a neglected disease. Few studies about the disease and expensive treatments make it difficult to reduce the morbidity and mortality of this condition. Public health services and physicians must be aware of histoplasmosis' burden among the HIV-positive population.