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This article describes the development of the pathogenic dimorphic fungus Histoplasma capsulatum var. farciminosum (HCF), which is the causative agent of Equine epizootic lymphangitis (EEL), from the mycelial form in the soil to the yeast form in the horse. In this study, the stages and morphology of HCF were identified through histopathological analysis and culture with various samples collected in Ethiopia from 15 horses showing clinical signs of EEL. In equids, especially cart horses in Ethiopia, poor-quality harnesses cause cutaneous wounds, which often attract flies facilitating the transmission of the fungus. Also, HCF infection occurs through open wounds or ocular mucous membranes when horses roll on contaminated damp soil. Respiratory histoplasmosis can occur through inhaling fungal spores, which is rare. HCF microconidia enter the lungs and skin wounds and are phagocytized by tissue-resident macrophages. The spores undergo intracellular replication within the macrophages transitioning into yeasts. The infected macrophages undergo lysis releasing pathogenic yeast cells into the surrounding tissue. Consequently, yeast-rich purulent exudate is produced, contaminating the soil in stables where yeast cells germinate into the mycelial form, and the entire process starts from the beginning.

Background Epizootic lymphangitis (EEL), caused by Histoplasma capsulatum var. farciminosum (HCF), is a neglected equine fungal disease lacking effective vaccines. The newly developed inactivated ‘8ZH’ vaccine requires safety validation in the target species. Objectives To evaluate the biochemical, haematological and clinical safety of the inactivated HCF ‘8ZH’ vaccine in foals. Methods A controlled, single‐blinded study was conducted on 30 clinically healthy foals (4–6 months), randomized into vaccinated (n = 15) and control (n = 15) groups. Vaccinated animals received a 5 mL intramuscular dose (10 mg antigen, MONTANIDE GEL 01 PR adjuvant) on Day 0 and a booster on Day 21. Clinical observations (temperature, appetite, behaviour, injection site) were recorded daily. Blood was collected at baseline and on Days 7, 14, 21, 35 and 42 for biochemical, haematological and acute‐phase protein analysis. Data were analysed using repeated measures ANOVA. Results No severe or adverse reactions were observed. Mild, transient injection‐site swelling (< 4 cm) occurred in three vaccinated foals and resolved spontaneously. All animals maintained normal temperature and appetite. AST showed a transient increase on Day 14 (p = 0.04); WBC also rose (p = 0.03), indicating a typical immune response. Other parameters, including ALT, GGT, creatinine, total bilirubin and acute‐phase proteins (SAA, fibrinogen, haptoglobin), remained within physiological limits. No statistically significant long‐term deviations or toxic effects were noted. Conclusions The inactivated HCF ‘8ZH’ vaccine demonstrated a favourable safety profile in foals. These results support its continued development for use in EEL prevention programs. This study assessed the biochemical and haematological safety of the inactivated Histoplasma capsulatum var. farciminosum ‘8ZH’ vaccine in foals. No adverse clinical signs or significant changes in liver, kidney or acute‐phase protein markers were observed. The results support the vaccine's safety and suitability for further immunogenicity evaluation in equine epizootic lymphangitis control.

Background Epizootic lymphangitis is an infectious and chronically debilitating disease of the equines. Histoplasma capsulatum var. farciminosum, a thermally dimorphic fungi, is the causative agent for the disease. In Ethiopia, the disease significantly affects carthorses, posing threats to animal welfare, and resulting in substantial economic losses. Limited availability of widely accessible antifungals in addition to the chronic nature of the disease is the major challenge against management of epizootic lymphangitis. This study aimed to assess the in vitro efficacy of specific local medicinal plant extracts against the mycelial phase development of H. capsulatum var. farciminosum in southern Ethiopia. The leaves of Xanthium strumarium , Kanda (Family Rubiaceae ), Croton macrostachyus ( Bisana in Amharic), and Centella Asiatica ( Echere waye as a local name in Zeyissegna) that are traditionally used for the treatment of different skin ailments were collected and extracted for the in vitro trial. Results The study revealed that methanol extracts of Xanthium strumarium , Kanda , Croton macrostachyus , and Centella Asiatica , at minimum inhibitory concentrations of 1.25 mg/ml, 2.5 mg/ml, 2.5 mg/ml, and 5 mg/ml, respectively, inhibited the growth of H. capsulatum var. farciminosum . Conclusion This in vitro finding could serve as significant preliminary data in the exploration of effective alternative treatment options for epizootic lymphangitis. This study provides a crucial foundation for further research aimed at determining the chemical components and in vivo effectiveness of these plant extracts against both the mycelial and yeast forms of Histoplasma capsulatum var. farciminosum .

Background Epizootic lymphangitis (EL), caused by Histoplasma capsulatum variety farciminosum (HCF) is a contagious, chronic disease of equines, characterized by development of nodular lesions in the lymph nodes, lymphatic vessels and skin. It is one of the most important diseases of equines in Ethiopia, causing significant economic loss, particularly in the livelihood of carthorse owners. To date there is neither effective diagnostic nor control measure implemented in the country. Furthermore, there is a shortage of data on the epidemiology of the disease in different regions of this country. The aim of this study was to investigate epidemiology of EL in northern Ethiopia, using the conventional methods as well as nested polymerase chain reaction (PCR). Results The presence of HCF genetic material was confirmed in 44% (84/191) of the carthorses. Subclinical infection was observed in 18.2% (22/121) of the apparently healthy carthorses. Considering the nested PCR as a gold standard, sensitivity and specificity of clinical examination were 74% and 92.5%, respectively, while the area under the ROC curve (AUR) was 0.83 (95% confidence interval, 0.77, 0.896). Moreover, a moderate ( k  = 0.675) agreement observed between the nested PCR and clinical examination. Conclusions This study demonstrated widespread occurrence of EL in northern Ethiopia, and the advantage of the nested PCR in detecting infection of HCF, even before the clinical symptoms became apparent.

We report the first case of central nervous system histoplasmosis caused by Histoplasma capsulatum var. duboisii in a patient with no underlying immunodeficiency. African histoplasmosis is an underdiagnosed endemic fungal infection which should be included in the differential diagnosis of cerebral lesions in patients originating from Western and Central Africa.

Histoplasmosis is an endemic disease caused by . 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 as the etiological agent of the lesions in the bone biopsy. Through phylogenetic tree analysis, ( ) 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.

Report on epizootic lymphangitis, a chronic contagious zoonosis of Equidae caused by Histoplasma capsulatum var. farciminosum characterized clinically by pyogranulomatous multifocal dermatitis with lymphadenitis, is rare in donkeys. This case reports a 6-year-old, 200-kg local male donkey at the University of Ibadan zoological garden with wounds on its dorsum which developed into ulcerative lesions on the left cranial thoracic region. The lesions were also along the lymphatic drainage of the left infrascapular area down to the girth with extensive nodular lesions on the skin, characteristic focal ulcers and fenestrations along the left flank. The ulcers were recurrent with blockage of the left lymphatic drainage causing ventral edema of the sternum extending to the prepuce and the left forelimb. The wound was managed for about 1 year but remained persistent with episodes of apparent healing, scarification and recurrence. Tentative diagnosis of epizootic lymphangitis was made. Blood sample, pus swab and aspirated exudate were collected for confirmatory diagnosis using light microscopy and polymerase chain reaction (PCR) to detect and amplify a fragment of the internal transcribed spacer-2 (ITS-2) gene. These techniques detected Histoplasma capsulatum var. farciminosum, which informed the use of appropriate therapeutic agents, providone iodine wash, and griseofulvin cream and tablets for 3 weeks to treat the disease condition.

Disseminated histoplasmosis is caused by the dimorphic fungus Histoplasma capsulatum (H. capsulatum). The early clinical manifestations are nonspecific, often lead to diagnostic difficulty, and is misdiagnosed as tuberculosis and seen usually in immunosuppressed states. Fine needle aspiration cytology (FNAC) is a simple, safe, and quick technique to establish the initial diagnosis of H. capsulatum, thereby prompting early treatment. The skin involvement is rare in disseminated disease and we describe a case of disseminated histoplasmosis in an immunocompetent patient with unusual molluscum contagiosum like umbilicated skin lesions and FNAC of the cervical lymph node was the only tool for rapid and early confirmatory diagnosis.

Histoplasma capsulatum is a pathogenic fungus that causes life-threatening lung infections. About 500,000 people are exposed to H. capsulatum each year in the United States, and over 60% of the U.S. population has been exposed to the fungus at some point in their life. We performed genome-wide population genetics and phylogenetic analyses with 30 Histoplasma isolates representing four recognized areas where histoplasmosis is endemic and show that the Histoplasma genus is composed of at least four species that are genetically isolated and rarely interbreed. Therefore, we propose a taxonomic rearrangement of the genus. IMPORTANCE The evolutionary processes that give rise to new pathogen lineages are critical to our understanding of how they adapt to new environments and how frequently they exchange genes with each other. The fungal pathogen Histoplasma capsulatum provides opportunities to precisely test hypotheses about the origin of new genetic variation. We find that H. capsulatum is composed of at least four different cryptic species that differ genetically and also in virulence. These results have implications for the epidemiology of histoplasmosis because not all Histoplasma species are equivalent in their geographic range and ability to cause disease. The evolutionary processes that give rise to new pathogen lineages are critical to our understanding of how they adapt to new environments and how frequently they exchange genes with each other. The fungal pathogen Histoplasma capsulatum provides opportunities to precisely test hypotheses about the origin of new genetic variation. We find that H. capsulatum is composed of at least four different cryptic species that differ genetically and also in virulence. These results have implications for the epidemiology of histoplasmosis because not all Histoplasma species are equivalent in their geographic range and ability to cause disease.