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Inquiring Minds Want to Know: Infectious Disease

Infectious Disease Common Conditions and Diseases

By Audrey Kirchner, CHDS



When we transcribe infectious disease reports, we encounter the specialty that deals with the diagnosis, control, and treatment of infections. There are many different types of infectious diseases,
however. Let’s take a look at some of the most common.


Cellulitis. Cellulitis is a bacterial inflammation or infection of the skin and the tissues below the skin. The most common symptoms include swelling, redness of the skin, tenderness to the touch, and even warmth. The bacteria causing the infection
can quickly spread to the bloodstream and lymph nodes and become a life-threatening illness. The most common treatment is antibiotics, usually IV. Failure to control cellulitis can result in amputation and even death if a bloodstream infection occurs.


Meningitis. This is an infection involving the meninges (the protective covering surrounding the brain and spinal cord). There are several different kinds of meningitis. Bacterial meningitis is caused by bacteria which need to be eradicated. Viral
is usually less severe than bacterial and can be caused by a number of viruses or diseases, including measles, mumps, or other viral entities. Parasitic meningitis is caused by a specific parasite and most often is fatal. Fungal meningitis is caused
by certain fungi which can be inhaled (such as from bird or bat droppings) and can be treated effectively with antibiotics. Noninfectious meningitis is usually the result of another disease, such as lupus or cancer. The symptoms are relatively parallel
including headache, fever, malaise, nausea, vomiting or even coma (depending on the severity and the type of meningitis).


Sepsis. This is the potentially life-threatening complication of an infection of some kind. It can be due to a UTI or due to a wound as examples. Systemic symptoms occur to include tachycardia, fever, elevated white count, and hypotension. If untreated,
sepsis can progress rapidly and result in end-organ damage such as kidney failure due to lack of renal perfusion in the setting of low blood pressure. Untreated sepsis may result in SIRS (systemic inflammatory response syndrome), an inflammatory state
affecting the entire body.


West Nile virus. This is a virus transmitted to humans by way of mosquitos. Roughly 80% of people bitten have little to no symptoms. However, some people are severely affected. Most often symptoms include headache, malaise, skin rash or swollen
lymph nodes. However, if West Nile virus enters the brain, it can be fatal, causing inflammation of the brain tissues resulting in encephalitis. The elderly and people with weakened immune systems are at highest risk. To date, there is no vaccine
or preventive treatment available for this virus.


Zika virus. The Zika virus is also a disease transmitted by mosquitos. The symptoms are similar to West Nile but may also include conjunctivitis and joint inflammation. Different from West Nile, however, the Zika virus may also cause Guillain-Barre,
a condition in which the immune system attacks the body’s nerves causing tingling and weakness, sometimes quite severe and debilitating to the point of paralysis.  


Rotavirus. This is the most common gastrointestinal virus worldwide and kills more than 500,000 children each year. Symptoms include diarrhea, vomiting, fever, and abdominal pain. The virus infects the bowel and is most commonly found in children.
It is estimated that most children will commonly have at least 1 rotavirus infection before the age of 5.


Shigellosis. Shigellosis is caused by the bacteria Shigella. It is a bacterial infection of the intestine caused by Shigella bacteria. While it is widely prevalent in developing countries due to poor sanitation, it can occur in any country and
claims about 600,000 lives per year. The most common symptom is bloody diarrhea. It can be passed through contaminated food or even swimming in impure water.


Influenza. This is a viral infection that causes symptoms of upper respiratory infection but can include systemic symptoms such as headache and fever. It affects millions of people every year and is most prominent as a respiratory tract infection.


Pneumonia. There are several types of pneumonia and dependent upon the person’s immune system stability, it can be life-threatening or treatable. There are different kinds from so-called walking pneumonia (relatively mild and much like a URI) to
bacterial pneumonia which can be fatal. There are streptococcal pneumonias and pneumococcal pneumonias. Mycoplasma is another strain of pneumonia that can have dire consequences if a person is immunocompromised. Pneumonia organisms can live in the
body for years and never surface until another disease leaves the patient in a weakened state and then flare seemingly with no cause. There are different types of pneumonia as well associated with the healthcare profession such as healthcare-acquired
pneumonia (HAP) or community-acquired pneumonia (CAP). The treatment of the different types of pneumonia depend upon the source and also the severity of the disease in the individual patient.


These are just a few of the many types of conditions and diseases we find in the specialty of infectious disease. In general, infectious diseases are disorders that are caused by organisms such as bacteria, a virus, a fungus or a parasite. Many of these
organisms live in or on our bodies and can be helpful or harmless but under certain conditions, they can become dangerous diseases that can even be fatal. Some of these diseases can also be passed from one person to another.