Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
Histoplasmosis has three major types of disease, and these three have other
subtypes included in them. They are summarized with their subtypes as follows:
acute pulmonary histoplasmosis; asymptomatic and symptomatic;
chronic pulmonary histoplasmosis; chronic lung symptoms and occasionally
ocular involvement termed ocular histoplasmosis syndrome; and
progressive disseminated histoplasmosis: chronic progressive disseminated
histoplasmosis with oropharyngeal lesions or ulcers; subacute progressive
disseminated histoplasmosis with intestinal, adrenal, cardiac or central nervous
system (CNS) involvement; and acute progressive disseminated histoplasmosis with
encephalopathy, meningitis, mass lesions and cutaneous (skin) lesions.
Drawings and pictures of some of the different types of histoplasmosis are
available at the last Web site listed below.
How is histoplasmosis transmitted?
Histoplasmosis is not transmitted person to person except for a few rare
instances when a transplant patient has contracted histoplasmosis from a
transplanted organ. The large majority of cases occur when people inhale fungal
mycelia and spores, usually from a source where the fungus growth is enhanced.
Such sources or areas are in caves containing bat or bird droppings, chicken
coops, birdhouses, bird roosts, or soil contaminated with such droppings.
Unfortunately, H. capsulatum can survive in soil for years, and if the soil
becomes airborne (dust), inhalation of H. capsulatum-contaminated dust may lead
to histoplasmosis.
How is histoplasmosis diagnosed?
Definitive diagnosis of histoplasmosis can be complicated, especially if the
patient gives no history of exposure to areas contaminated with H. capsulatum.
Many bacterial and fungal infections can produce clinical findings that are
found with H. capsulatum infections (for example, granulomatous nodules found in
sarcoidosis and tuberculosis, or lung infiltrates seen on X-ray in coccidiodomycosis, blastomycosis, aspergillosis, and other lung infections). In
fact, before 1932, many patients with chronic pulmonary histoplasmosis were
diagnosed as having tuberculosis. Differentiating histoplasmosis from other lung
infections can still be a diagnostic challenge for clinicians.
Cultures of blood, sputum, or tissue biopsy samples can be cultured on media that
supports H. capsulatum growth. If H. capsulatum is cultured, the diagnosis is
confirmed. However, at best, cultures are positive in only about 60% of patients
with chronic pulmonary infections and are positive in only about 15% of acute
cases. Furthermore, it may take from two to 12 weeks for the fungus to grow enough
to be identified in culture, which could delay treatment especially in
progressive disseminated cases. Blood cultures range from 50%-90% positive in
progressive disseminated cases. Positive cultures for H. capsulatum definitively
diagnose histoplasmosis. Unfortunately, acute progressive disseminated
histoplasmosis, if not treated quickly and appropriately, can lead to death in a
few weeks. In suspected cases, treatment should begin immediately without
waiting on cultures to grow positive for H. capsulatum.
There are several types of serology tests (tests for antigens and antibodies)
that are used on blood, urine, and cerebral spinal fluid (CSF). They can give
fairly rapid results especially with symptomatic, chronic, or progressive
disseminated disease (75%-95% positive after six weeks) but take about three weeks to
be positive in a small number (about 15%) of acute cases. Unfortunately, the
reagents share some cross-reactivity with other fungal genera (for example,
Aspergillus, Blastomyces, and Coccidioides), so false-positive results can be
obtained. Further, these tests for H. capsulatum can be positive in people that
live in areas with endemic histoplasmosis and also can be positive in patients
that have inactive disease.
Stains (Giemsa stain or methenamine silver stain) of tissue samples, blood,
sputum, bone marrow, lymph node aspirates, and other fluids can allow
microscopic visualization of H. capsulatum. However, the accuracy of
identification depends on the experience of the observer as other organisms may
resemble H. capsulatum. Researchers suggest this method be backed up by other
tests such as serology and cultures.
Many other tests may be used to help the physician determine the extent of
infection by H. capsulatum. Examples are listed below:
CBC or complete blood count: Low white blood cell counts can occur in chronic
progressive histoplasmosis.
Chest X-rays can show lung changes (infiltrates, cavitations, and enlarged
lymph nodes) that may occur in chronic and acute progressive disseminated
histoplasmosis.
CT scan may show bilateral adrenal gland involvement in subacute progressive
disseminated histoplasmosis.
Echocardiography helps determine if heart valves are infected or if
pericarditis is present in acute pulmonary or progressive disseminated
histoplasmosis.
Alkaline phosphatase levels in the blood are increased in chronic pulmonary
and acute progressive disseminated histoplasmosis.
Other tests and procedures may be done to help determine the diagnosis or extent
of infection; those listed above are the most common. Occasionally, a surgeon
may need to be consulted to obtain lung tissue, pleural fluid, or lymph node
biopsy for culture and microscopic evaluation to aid diagnosis.
Abdominal pain is pain in the belly and can be acute or chronic. Causes include inflammation, distention of an organ, and loss of the blood supply to an organ. Abdominal pain can reflect a major problem with one of the organs in the abdomen such as the appendix, gallbladder, large and small intestine, pancreas, liver, colon, duodenum, and spleen.
Pneumonia is inflammation of one or both lungs with consolidation. Pneumonia is frequently but not always due to infection. The infection may be bacterial, viral, fungal or parasitic. Symptoms may include fever, chills, cough with sputum production, chest pain, and shortness of breath.
Headaches can be divided into two categories: primary headaches and secondary headaches. Migraine headaches, tension headaches, and cluster headaches are considered primary headaches. Secondary headaches are caused by disease. Headache symptoms vary with the headache type. Over-the-counter pain relievers provide short-term relief for most headaches.
Lymph nodes help the body's immune system fight infections. Causes of swollen lymph nodes (glands) may include infection (viral, bacterial, fungal, parasites). Symptoms of swollen lymph nodes vary greatly. They can sometimes be tender, painful or disfiguring. The treatment of swollen lymph nodes depends upon the cause.
Chronic cough is a cough that does not go away and is generally a symptom of another disorder such as asthma, allergic rhinitis, sinus infection, cigarette smoking, GERD, postnasal drip, bronchitis, pneumonia, medications, and less frequently tumors or other lung disease. Treatment of chronic cough is dependant upon the cause.
Although a fever technically is any body temperature above the normal of 98.6 degrees F. (37 degrees C.), in practice a person is usually not considered to have a significant fever until the temperature is above 100.4 degrees F (38 degrees C.). Fever is part of the body's own disease-fighting arsenal: rising body temperatures apparently are capable of killing off many disease- producing organisms.
Chest pain is a common complaint by a patient in the ER. Causes of chest pain include broken or bruised ribs, pleurisy, pneumothorax, shingles, pneumonia, pulmonary embolism, angina, heart attack, costochondritis, pericarditis, aorta or aortic dissection, and reflux esophagitis. Diagnosis and treatment of chest pain depends upon the cause and clinical presentation of the patient's chest pain.
Epilepsy is a brain disorder in which the person has seizures. There are two kinds of seizures, focal and generalized. There are many causes of epilepsy. Treatment of epilepsy (seizures) depends upon the cause and type of seizures experienced.
Obesity is the state of being well above one's normal weight. A person has traditionally been
considered to be obese if they are more than 20 percent over their ideal weight.
That ideal weight must take into account the person's height, age, sex, and
build.
AIDS is the advanced stage of HIV infection. Symptoms and signs of AIDS include pneumonia due to Pneumocystis jiroveci, tuberculosis, toxoplasmosis, seizures, weakness, meningitis, yeast infection of the esophagus, and Kaposi's sarcoma. Anti-retroviral therapy (HAART) is used in the treatment of AIDS.
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