Histoplasma species infect humans and animals, notably bats. Histoplasma species are thermally dimorphic fungi existing in mycelial form in the natural environment and in yeast form in infected tissues. In this narrative literature review, we summarize the occurrence of Histoplasma spp. in different species of bat tissues (n = 49) and in soil admixed with bat guano where the species of bat dwelling nearby has been identified (an additional 18 species likely infected) to provide an up-to-date summary of data. Most positive isolations are from the Americas and Caribbean, with some studies from Thailand, Malaysia, Nigeria, Slovenia, France, and Australia. We also summarize some of the early experimental work to elucidate pathogenicity, latency, immune response, and faecal excretion in bats. Given the recent recognition of the global extent of histoplasmosis, thermal dimorphism in Histoplasma spp., and global heating, additional work on understanding the complex relationship between Histoplasma and bats is desirable.
Histoplasmosis is a fungal infection caused by Histoplasma capsulatum. Although uncommon, it should be considered among the list of important opportunistic infections in severely immunocompromised patients. Patients living with AIDS are at particular risk of disseminated histoplasmosis. Diagnosis requires a high level of clinical suspicion. The infection is best confirmed by demonstration of the organism in tissue specimens or by culture. Amphotericin B is the most effective drug for severe disseminated histoplasmosis. Response is good but life-long maintenance is required to prevent relapse.
Histoplasmosis infection is endemic in Asia and disseminated histoplasmosis (DH) is one form of its presentation (Benevides et al., 2007[1]). DH commonly affects both adrenal glands. We describe a case of disseminated histoplasmosis complicated with hypercalcaemia in a 75-year-old immunosuppressed patient who presented with bilateral adrenal masses. The fine needle aspiration cytology of the adrenal mass was positive for Histoplasma capsulatum.
A 40-year-old man presented with chronic mouth ulcer for the last six months. Histopathological examination of the biopsy from the lesion confirmed a diagnosis of histoplasmosis. Although histoplasmosis commonly manifests in immunocompromized patients, like HIV, the present case was negative for HIV. Histoplasmosis is endemic in certain parts of the world and it is comparatively rare in the South Asian region, particularly Malaysia. Thirty-seven cases of histoplasmosis were reported from Malaysia (Ng and Siar, 1996), between July 1967 and October 1997. Despite the apparent rarity of the disease, clinicians and pathologists should be aware of the possibility of histoplasmosis when cases of oral ulcer are encountered.
A 51-year old man presented with a persistent tongue ulcer, fever, cervical lymphadenopathy and hepatomegaly. The diagnosis was initially thought to be tuberculosis. This led to the initiation of antituberculous chemotherapy to which the patient failed to respond. The correct diagnosis of histoplasmosis was made after the detection of Histoplasma capsulatum on further review of the tongue ulcer biopsy specimen. He responded to treatment with amphotericin B.
We report a case of a healthy 78-year-old indonesian man who presented with chronic weight loss, poor appetite and lethargy. CT abdomen showed bilateral adrenal masses. EUS-guided FNA was performed on the left adrenal gland. Histopathology report was Histoplasma Capsulatum. He recovered well with antifungal treatment without any complication. In this case, we found that the role of EUS -guided FNA was not only limited to diagnosis but also helped in the prognosis of the disease since the method was able to assess the general anatomy of the adrenal gland better than other imaging modalities due to its close proximity and direct visualization.
Histoplasmosis, caused by Histoplasma capsulatum, is an endemic mycosis in many countries of the world except for Japan. Outbreaks of histoplasmosis among Japanese people are very rare and are mainly imported by travelers. We report an outbreak of histoplasmosis among healthy Japanese people who traveled to a resort area in Southeast Asia. Three young Japanese women traveled to Langkawi island, Malaysia and stayed on the island for five days without visiting caves, a known reservoir of H. capsulatum. All three individuals developed flu-like symptoms with multiple nodule shadows on chest X rays or chest CT scans at around ten days after their return to Japan. Serum samples obtained from the three subjects were positive for anti-Histoplasma antibody and specific PCR for H. capsulatum on lung biopsy specimens and the serum from one patient was positive. The clinical course of all three patients improved without the use of anti-fungal agents and no recurrence has been confirmed. Clinical attendants should consider histoplasmosis when they see patients with flu-like symptoms with abnormal chest X-rays after visiting H. capsulatum endemic areas, especially Southeast Asia.
Histoplasmosis caused by the fungus Histoplasma capsulatum is often lethal in patients with AIDS. Urine antigen testing is highly sensitive and much quicker for diagnosis than culture. Histoplasmosis has a patchy and incompletely appreciated distribution around the world especially in South East Asia. We conducted a systematic literature review of cases of all disease forms of histoplasmosis in SE Asia, not including the Indian sub-continent. We also reviewed all histoplasmin skin test mapping studies to determine localities of exposure. We found a total of 407 cases contracted or likely to have been contracted in SE Asia. Numbers of cases by country varied: Thailand (233), Malaysia (76), Indonesia (48) and Singapore (21), with few or no cases reported in other countries. Most cases (255 (63%)) were disseminated histoplasmosis and 177 (43%) cases were HIV associated. Areas of high histoplasmin skin test sensitivity prevalence were found in Myanmar, the Philippines, Indonesia, Thailand and Vietnam - 86.4%, 26.0%, 63.6%, 36.0% and 33.7%, respectively. We have drawn maps of these data. Further study is required to ascertain the extent of histoplasmosis within SE Asia. Diagnostic capability for patients with HIV infection is urgently required in SE Asia, to reduce mortality and mis-diagnosis as tuberculosis.
We describe a 2 year-old non-immunocompromised girl with disseminated histoplasmosis who presented with a 2-month history of fever and bloody diarrhoea. On presentation, she was severely wasted and anaemic. There were gross hepatosplenomegaly and multiple lymphadenopathy. A septic screen was negative. A subsequent stool culture isolated Salmonella enteriditis. Serial Widal-Weil Felix (WWF) titres showed serological response after 2 weeks of Ceftriaxone. However, she continued to have spiking fever, bloody diarrhoea and weight loss. She developed pancytopaenia and disseminated intravascular coagulation. A bone marrow aspirate and trephine, and lymph node biopsy showed the presence of Histoplasma capsulatum, confirmed by Gomori-Methenamine Silver staining. She responded to intravenous amphotericin B followed by fluconazole (intravenous then oral) for 6 months after discharge. Human Immunodeficiency Virus screening tests were negative. Complement and immunoglobulin levels were normal. T and B enumeration tests showed gross leucopaenia with very low T cell function with defective phagocytic function. A repeat T and B cell enumeration test and phagocytic function tests done 3 months later were normal.
Isolated laryngeal histoplasmosis is a very rare entity. It has variable clinical presentations that might mimic both benign and malignant lesions, and is usually associated with pulmonary and other disseminated forms of histoplasmosis. Herein, we report a case of primary laryngeal histoplasmosis without the involvement of other systems in a 70-year-old Chinese man, who previously worked as a miner. He presented with a history of hoarseness for two months, with no other associated symptoms. Direct laryngoscopy revealed irregularity of the posterior one-third of both vocal folds. Histopathological examination revealed the presence of Histoplasma capsulatumon periodic acidSchiff and Grocott's methenamine silver staining. The lesion resolved after one month of oral itraconazole treatment. However, the patient had to complete six months of antifungal treatment to prevent recurrence.
Histoplasmosis is a systemic fungal infection caused by inhalation of Histoplasma capsulatum, which is mainly found in bird and bat droppings. Oral manifestation of histoplasmosis may be the only initial manifestation of the disease or associated with chronic disseminated histoplasmosis. The first review of oral histoplasmosis among Malaysian population from 1967 to 1994 (27 years) revealed the occurrence of 37 cases, reported by Ng and Siar in 1996. This current study is the updated overview of oral histoplasmosis cases in Malaysia. The objective of the study was to review and describe clinical and demographic profile of oral histoplasmosis in Malaysia and to correlate histopathological features of oral histoplasmosis with patient's immunity status. We reviewed oral histoplasmosis cases diagnosed in Stomatology Unit, Institute for Medical Research (IMR), Kuala Lumpur from 1995 until 2016. The data was retrieved from the Oral Pathology Information system (OPIS) Stomatology Unit, IMR, which is the largest oral pathology database in Malaysia. Information regarding patients' sociodemographic data, medical illness, clinical presentation, histopathological features, and referring healthcare institutions was extracted from the clinical information which accompanied the biopsy request form. A total of 39 cases of oral histoplasmosis were identified from 1995-2016. Majority of them were male (89.7%). The age ranges from 29 to 85 years with mean age of 57.8 years. Almost half of them were Malays (51.3%), followed by Chinese (33.3%), Indians (7.7%), and other races (7.7%). The most common sites of oral histoplasmosis were tongue, gingiva, palate, and alveolar ridge. The main clinical presentation was ulcer (61.5%) whereas 38.5% presented clinically as swelling. 17.9% of patients were seropositive for human immunodeficiency virus (HIV), 12.8% had tuberculosis, 10.3% had diabetes mellitus, and 2.6% with hepatitis C. The incidence of oral histoplasmosis should raise suspicion of hidden immunodepression and may be the first manifestation of acquired immunodeficiency syndrome (AIDS). Early recognition and diagnosis is crucial to reduce risk of morbidity and mortality.