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Histoplasmosis is a respiratory infection. Most initial infections are asymptomatic to mild.

Eg:- Flu-like illness(Fever, Headache, Chest pain, weight loss) So, Laboratory diagnosis of histoplasmosis is a very important and difficult task in the laboratory

Patient may have severe pneumonia associated with hepatomegaly & splenomegaly.

Laboratory diagnosis of histoplasmosis

The most common way that healthcare providers test for Histoplasmosis is by taking a blood sample or urine sample.

Sputum

Bone marrow

Lesion scraping

Biopsy specimens also can be used to diagnose histoplasmosis

1.Direct examination

Sputum – KOH

Tissue specimens – PAS, GMS, Giemsa stains for fungi – Routine histology: H & E



2.Culture

Sabouraud dextrose agar(SDA) with cycloheximide & chloramphenicol, 25 celsius for 2-6 weeks give white-brown mould.

3.Serology

Complement fixation test

Sensitivity and specificity vary according to the stage and form of the disease.

Eg:- Acute pulmonary – sensitivity 5-15% at 3 weeks

Chronic pulmonary – sensitivity 70-90% at 6 weeks

4.Immunodiffusion

It is more specific and less sensitive.

M bands Prior exposure Acute and chronic diseases

H bands Diagnostic of acute disease



5.ELISA/RIA

Sensitivity is high and specificity is low compared to CFT

6.Ag detection

Presence of Histoplasma Ag in urine is indicative of current or recent infection

Serum sensitivity is lower

Nematode eggs identification – https://medilabzone.com/nematode-eggs-identification/

Hemolytic disease of new born (HDN) – https://medilabzone.com/hemolytic-disease-of-the-newborn-hdn/

Laboratory diagnosis of rabies virus | Negri bodies identification – https://youtu.be/mz7c-hiGdcw