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 is caused by a dimorphic (two forms, mycelia and yeast) fungus
named Histoplasma capsulatum. The genus name is misleading; the fungus has no
capsule, but early investigators mistakenly thought it did. The mycelial phase
consisting of mycelia fragments and spores can be inhaled and may reach the lung
alveoli. Macrophages (human phagocytic cells of the immune system) surround and
engulf (phagocytosis) H. capsulatum, which then changes inside the macrophages
to the yeast form in about 15-18 hours. In most cases, the macrophage response
kills the yeast. When macrophages fail to kill all the yeast, a variation of the
disease develops because the yeast form multiplies and invades other cells. The
larger the number of mycelia and spores the person is exposed to, the more
likely the person will develop symptomatic disease.
What are the symptoms and signs of histoplasmosis?
About 90% of infections caused by H. capsulatum are asymptomatic (produce no
symptoms). Occasionally, a few asymptomatic patients will show small scars in
lung X-rays. Symptomatic people often develop fever, chills, dry cough,
malaise, sweats, and abdominal pains about three to 14 days after exposure. If the
disease progresses, symptoms such as weight loss, fatigue, dyspnea, chest pain,
and reduced or loss of vision may occur. A sign of progression are patchy
infiltrates seen on chest X-rays, usually in the lower lung fields. Other
symptoms that can occur, especially in patients that are immunosuppressed, are
mouth ulcers, fevers, headaches, confusion, seizures, encephalopathy, and
infrequently, death.
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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