Video:Histoplasmosis

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Description

Histoplasmosis is a fungal infection caused by Histoplasma capsulatum.[1][2] Symptoms range widely, but primarily involve the lungs.[3] Occasionally, other organs are affected; known as disseminated histoplasmosis, which can be fatal if left untreated.[4]

Presentation

As to the presentation we find that the individual can be asymptomatic or display fever, headache, nonproductive cough, and chest pain.[5]

Complications

In terms of the possible complications we find respiratory failure, fibrosing mediastinitis, pulmonary vessel obstruction, and progressive fibrosis. Smokers with structural lung disease have higher probability of developing chronic cavitary histoplasmosis;after healing of lesions, hard, calcified lymph nodes can erode the walls of the airway, causing hemoptysis.[6][7][8][9]

Cause

Histoplasma capsulatum is a species of dimorphic fungus. It can cause pulmonary and disseminated histoplasmosis.Its sexual form is called Ajellomyces capsulatus.[5]

Mechanism 1

The inoculum is represented principally by microconidia. These are inhaled and reach the alveoli, in the alveoli, macrophages ingest these microconidia, they survive inside the phagosome. As the fungus is thermally dimorphic, these microconidia are transformed into yeast. They grow and multiply inside the phagosome. The macrophages travel in lymphatic circulation and can spread the disease to different organs.Within the phagosome, the fungus has an absolute requirement for thiamine.Cell-mediated immunity for histoplasmosis develops within 2 weeks. [10][11][5]

Mechanism 2

If the individual has strong cellular immunity, macrophages, epithelial cells, and lymphocytes surround the organisms and contain them, and eventually calcify. In immunocompromised individuals, the organisms disseminate to different organs such as bone, spleen, liver, adrenal glands, and mucocutaneous membranes, resulting in progressive disseminated histoplasmosis.[10][5][11]

Diagnosis

In terms of the evaluation we find that blood tests, urine antigen test, as well as sputum or lung tissue samples can be done during the diagnosis.[5][12]

Differential diagnosis

The differential diagnosis of Histoplasmosis includes: fungal pneumonia, bacterial pneumonia, Blastomycosis, and carcinoid lung tumours.[5]

Treatment

In the majority of immunocompetent individuals, histoplasmosis resolves without any treatment. Antifungal medications are used to treat severe cases of acute histoplasmosis and all cases of chronic and disseminated disease. Typical treatment of severe disease is with amphotericin B, followed by itraconazole by mouth.[13][14]

Epidemiology 1

H. capsulatum is found throughout the world. It is endemic in certain areas of the United States, particularly in states bordering the Ohio River valley and the lower Mississippi River. The humidity and acidity patterns of soil are associated with endemicity. Bird and bat droppings in soil promote growth of Histoplasma. Contact with such soil aerosolizes the microconidia, which can infect humans. It is also common in caves in Southern and East Africa. Positive Histoplasmin skin tests occur in as many as 90 percent of the people living in areas where H. capsulatum is common, such as the eastern and central United States.[3]

Epidemiology 2

In Canada, the St. Lawrence River Valley is the site of the most frequent infections, with 20 to 30 percent of the population testing positive.[15]A review of reported cases in 2018 showed disease presence throughout Southeast Asia.[16]In India, the Gangetic West Bengal is the site of most frequent infections, with 9 (point) 4 percent of the population testing positive.[17]

History

Histoplasma was discovered in 1905 by Samuel T. Darling,[18] but only in the 1930s was it discovered to be a widespread infection.Before then, many cases of Histoplasmosis were mistakenly attributed to tuberculosis, and patients were mistakenly admitted to tuberculosis sanatoria. Some patients contracted tuberculosis in these sanatoriums.[19]

References

  1. ↑ Johnstone, Ronald B. (2017). "25. Mycoses and Algal infections". Weedon's Skin Pathology Essentials (2nd ed.). Elsevier. p. 452. ISBN 978-0-7020-6830-0. Archived from the original on 2021-05-25. Retrieved 2021-06-18.
  2. ↑ Stenn F (February 1960). "Cave disease or speleonosis". Archives of Internal Medicine. 105 (2): 181–3. doi:10.1001/archinte.1960.00270140003001. PMID 13834312.
  3. ↑ 3.0 3.1 Ryan KJ, Ray CG, eds. (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. pp. 674–6. ISBN 978-0-8385-8529-0.
  4. ↑ "Histoplasmosis - Infections". Merck Manual Consumer Version. Retrieved 15 December 2024.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Akram, Sami M.; Koirala, Janak (2024). "Histoplasmosis". StatPearls. StatPearls Publishing.
  6. ↑ Linder, Kathleen A.; Kauffman, Carol A. (1 September 2019). "Histoplasmosis: Epidemiology, Diagnosis, and Clinical Manifestations". Current Fungal Infection Reports. 13 (3): 120–128. doi:10.1007/s12281-019-00341-x. ISSN 1936-377X. Archived from the original on 28 July 2024. Retrieved 13 December 2024.
  7. ↑ Knox, Kenneth S.; Hage, Chadi A. (15 May 2010). "Histoplasmosis". Proceedings of the American Thoracic Society. 7 (3): 169–172. doi:10.1513/pats.200907-069AL. ISSN 1546-3222. Retrieved 14 December 2024.
  8. ↑ Wang, Aqian; Su, Hongling; Duan, Yichao; Jiang, Kaiyu; Li, Yu; Deng, Mingjun; Long, Xiaozhou; Wang, Haijun; Zhang, Min; Zhang, Yan; Cao, Yunshan (June 2022). "Pulmonary Hypertension Caused by Fibrosing Mediastinitis". JACC: Asia. 2 (3): 218–234. doi:10.1016/j.jacasi.2021.11.016.
  9. ↑ Kauffman, Carol A. (January 2007). "Histoplasmosis: a Clinical and Laboratory Update". Clinical Microbiology Reviews. 20 (1): 115–132. doi:10.1128/CMR.00027-06. ISSN 0893-8512.
  10. ↑ 10.0 10.1 Garfoot AL, Zemska O, Rappleye CA (2013) Histoplasma capsulatum depends on de novo vitamin biosynthesis for intraphagosomal proliferation. Infect Immum
  11. ↑ 11.0 11.1 Valdez, Alessandro F.; Miranda, Daniel Zamith; Guimarães, Allan Jefferson; Nimrichter, Leonardo; Nosanchuk, Joshua D. (31 December 2022). "Pathogenicity & virulence of Histoplasma capsulatum - A multifaceted organism adapted to intracellular environments". Virulence. 13 (1). doi:10.1080/21505594.2022.2137987. Archived from the original on 11 December 2024. Retrieved 14 December 2024.
  12. ↑ "Testing Algorithm for Histoplasmosis". Histoplasmosis. 16 May 2024. Retrieved 21 December 2024.
  13. ↑ Wheat LJ, Freifeld AG, Kleiman MB, Baddley JW, McKinsey DS, Loyd JE, Kauffman CA (October 2007). "Clinical practice guidelines for the management of patients with histoplasmosis: 2007 update by the Infectious Diseases Society of America". Clinical Infectious Diseases. 45 (7): 807–25. doi:10.1086/521259. PMID 17806045.
  14. ↑ Kurowski, Rene; Ostapchuk, Michael (15 December 2002). "Overview of Histoplasmosis". American Family Physician. 66 (12): 2247–2253. Archived from the original on 23 June 2024. Retrieved 4 December 2024.
  15. ↑ "Histoplasmosis". www.ccohs.ca. Canadian Centre for Occupational Health & Safety. July 1, 2013. Archived from the original on October 27, 2018. Retrieved June 6, 2021.
  16. ↑ Baker J, Setianingrum F, Wahyuningsih R, Denning DW (Jan 2019). "Mapping Histoplasmosis in South East Asia - implications for diagnosis in AIDS". Emerging Microbes & Infections. 8 (1): 1139–1145. doi:10.1080/22221751.2019.1644539. PMC 6711083. PMID 31364950.
  17. ↑ Sanyal M, Thammayya A (July 1975). "Histoplasma capsulatum in the soil of Gangetic Plain in India". The Indian Journal of Medical Research. 63 (7): 1020–8. PMID 1213788.
  18. ↑ Darling ST (1906). "A protozoan general infection producing pseudotubercles in the lungs and focal necrosis in the liver, spleen and lymphnodes". J Am Med Assoc. 46 (17): 1283–5. doi:10.1001/jama.1906.62510440037003. Archived from the original on 2021-08-28. Retrieved 2021-06-06.
  19. ↑ Bennett JE, Dolin R, Blaser MJ (11 September 2014). Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases" (8th ed.). ISBN 978-1455748013.
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