Many different types of infectious diseases affect the human population. Numerous viruses, bacteria and fungi are all capable of causing disease. They can directly invade and cause disease, or an infectious disease can develop as a result of complications. Disease can affect any part of the body. At times, the disease is intentional because it is due to a biological weapon.
Encephalitis
Encephalitis means the inflammation of the brain. Various viruses can cause this infectious disease if they can invade the brain. The herpes simplex virus 1 is the most common cause in America, according to Michael Jacewicz, M.D., professor of neurology at the University of Tennessee Health Science Center in “The Merck Manual for Healthcare Professionals.” Dr. Jacewicz writes that it usually affects people who are younger than 20 years old or older than 40 years old. People can also develop encephalitis from complications as a result of certain viral infections, including hepatitis A and B, influenza A and B, HIV and Epstein-Barr virus. The symptoms of encephalitis include seizures, headache, fever and mental confusion.
Anthrax
A bacterium named Bacillus anthracis causes anthrax. This infectious disease usually infects pigs, cattle, goats, sheep and horses. People normally contract anthrax if they handle contaminated animal hides or products, have contact with infected animals or inhale the spores of the bacteria, writes Brian Schwartz, M.D., assistant clinical professor at the University of California in “Current Medical Diagnosis & Treatment.” Anthrax has also become a biological weapon, when the spores are reduced to a fine powder. People with cutaneous anthrax, the skin disease, have a red lesion at first. The lesion then changes to purple or black, but it is usually painless. Other symptoms include nausea and vomiting, headache, fever, and swollen lymph nodes. People who inhale the spores may initially feel like they have the flu. But in hours or days, they develop a fever, low blood pressure and a rapid heart rate.
Coccidioidomycosis
A fungus called Coccidioides immitis causes this infectious disease. It is found in the southwestern part of the United States. Once people inhale the spores, the spores will change shape and become what are called spherules. The spherules will get larger and rupture. This sends thousands of new spores throughout the lungs. But the spores can spread beyond the lungs as well. People may develop lesions in their bones and skin, and even in the meninges membrane that covers the brain. Most people do not have any symptoms, as explained by Alan Sugar, M.D., professor emeritus of medicine at the Boston University School of Medicine in the “The Merck Manual for Healthcare Professionals.” Those who have symptoms may have a sore throat, chest pain, cough, fever and chills.
Otitis Externa
Otitis means inflammation of the ear. Otitis externa involves the inflammation of the external ear canal. It has the nickname of “swimmer’s ear,” but people can develop this infectious disease even if they were not swimming. Humidity, heat and the loss of the protective wax causes too much moisture in the ear canal. This creates the environment for an infection, writes Michael Rubin, M.D., Ph.D., assistant professor of medicine at the University of Utah School of Medicine in “Harrison’s Principles of Internal Medicine.” Pseudomonas aeruginosa is the main bacteria to cause this disorder. People may have symptoms that include itching in the ear, pain, and a red, swollen ear canal.
References
- “Current Medical Diagnosis & Treatment 2010”; Stephen McPhee, M.D., Maxine Papadakis, M.D.; 2010
- “Harrison’s Principles of Internal Medicine”; Anthony Fauci, M.D., Dennis Kasper, M.D., Dan Longo, M.D. et al.; 2008
- The Merck Manual for Healthcare Professionals: Coccidioidomycosis
- The Merck Manual for Healthcare Professionals: Encephalitis
