1. Skip to Menu
  2. Skip to Content
  3. Skip to Footer

Books

Available from ClinLab Navigator: Essentials of Transfusion Medicine, a convenient and comp...

Books
  • Books

    Books

  • Brand NEW APP - Lab Test Navigator: 800+ Lab Tests for iPhone

    Brand NEW APP - Lab Test Navigator: 800+ Lab Tests for iPhone

  • Brand NEW App - Lab Test Navigator: 800+ Lab Tests for iPad

    Brand NEW App - Lab Test Navigator: 800+ Lab Tests for iPad

Previous
Next

Histoplasma capsulatum

Histoplasma capsulatum is a dimorphic fungus, which exists as a mold in the environment and as a yeast at body temperature. Histoplasmosis is a common fungal infection in the United States that causes respiratory illness. Following infection, H. capsulatum is engulfed by macrophages and disseminated by the reticuloendothelial system. Symptoms include fever, headache, and respiratory symptoms, although infected persons can remain asymptomatic. Some patients progress to pneumonia and mediastinal or hilar lymphadenopathy. Most patients will recover regardless of treatment, but severe disease can lead to respiratory failure and should be treated. Immunocompromised patients are at high risk for developing systemic histoplasmosis.

Illness usually is acquired from inhalation of soil contaminated with bird or bat droppings. Endemic areas include the midwestern states, particularly the Mississippi and Ohio River valleys.  Human-to-human transmission does not occur. 

Disseminated histoplasmosis can be detected by culture, antigen detection, and/or serology. Culture of CSF fluid yields growth of H. capsulatum in about 50% of Histoplasma meningitis cases. Detection of H. capsulatum antigen in serum or urine has the highest sensitivity for disseminated disease (92%). Serial antigen testing is helpful in monitoring response to therapy. A confirmed case of histoplasmosis is defined as a serum or urine test positive for H. capsulatum, regardless of a person's symptoms. Antigen cross-reactivity may occur with other dimorphic mycoses such as blastomycosis.

Serologic detection of antibody to H. capsulatum is less sensitive than antigen testing, especially in immunosuppressed patients. Antibody testing is of limited usefulness in endemic regions where many individuals test positive. Antibody tests can be performed on serum or cerebrospinal fluid. Both complement fixation and immunodiffusion assays are available. Complement fixation measures total antibodies against both mycelial (mold) and yeast components of H. capsulatum and has higher sensitivity but lower specificity than immunodiffusion. Detection of antibodies to both H and M antigens is consistent with active infection. Detection of antibody to only the M antigen is seen in both current and past infection. Antibody to only H antigen is seldom seen and is not diagnostically useful.

Kauffman CA. Histoplasmosis: a clinical and laboratory update. Clin Microbiol Rev 2007;20:115–32.

Updated Articles

Chlamydia Detection

Chlamydia trachomatis infection is the most common sexually transmitted disease in the United States and Europe. Chlamydia causes an estimated four to five million infections each year in the United States. Men, women, and infants are affected, but…

New Articles

Carbohydrate…

Normal transferrin molecules contain 4 sialic acid residues. Chronic alcohol consumption causes a decrease in sialylation, leading to increased quantities of disialo- and asialotransferrin. Carbohydrate deficient transferrin (CDT) is used as a serum…

Blog

Hepatitis C Virus…

Many people with Hepatitis C virus (HCV) do not know they are infected. Since many people can live with HCV for decades without developing symptoms, testing is critical. HCV infection can progress to cirrhosis and hepatocellular carcinoma. Highly…

Stay Informed

Amazon Book

Our Sponsors

Login Form

Lectures

Cases That Kept Me Up At Night: Case #1

Case #1 is an overview of transfusion reactions and a discussion of a neonate with both NAIT and Rh HDN.

View More Lectures

Mobile Applications

iPad mini Horz Vert 300w

Get it for: iPhoneiPad

ClinLab Navigator Information

McAfee SECURE sites help keep you safe from identity theft, credit card fraud, spyware, spam, viruses and online scams
© 2015 ClinLab Navigator, LLC.