Mosquito-Borne Illnesses

Mosquitoes have historically plagued man with disease transmission, many of which have resulted in widespread death. The 1793 epidemic of yellow fever in Philadelphia was one such event. Nearly four thousand people or ten percent of Philadelphia’s urban population perished when a mosquito named Aedes aegypti, was transported on ships coming from the West Indies, where the disease Yellow Fever was endemic. Mosquitoes are known to spread numerous diseases and this article will discuss some of these mosquito-borne illnesses.

Dengue Fever

According to the CDC, Dengue Fever is caused by one of four closely related, yet different virus serotypes. The virus comes from the genus Flavivirus, with each serotype labeled as DEN1, DEN2, DEN3 and DEN 4. When infection occurs with one of the above serotypes, immunity will only be for that serotype. As a result, anybody can have multiple bouts of Dengue Fever during their lifetime.

The Aedes aegypti mosquitoes, that cause this disease, live in the tropics of Africa, Asia and the Americas. Symptoms can include fever, headache, muscle and joint pain, nausea, diarrhea and a bright red rash. The disease can also affect the platelets, which can lead to bruising and prolonged bleeding and in serious cases can lead to something called Dengue Shock Syndrome (DSS), that can lead to hypotension and death. There currently is no cure for the disease, so people with the disease need supportive therapy as quickly as possible, in order to get well. Mosquito control procedures and preventive measures will also help to minimize infection.

Malaria

Malaria is a disease that’s spread by the bite of an infected Anopheles mosquito. A protozoan, in the mosquito's saliva, enters the bloodstream and travels to the liver, killing many liver cells, before attacking and destroying a person's red blood cells. According to the CDC between three hundred to five hundred million infections occur a year, resulting in over one million deaths annually. The disease is more prevalent in Central and South America, Africa, Asia, Eastern Europe and the South Pacific.

Symptoms include fever and flu-like complaints, including chills, headache, confusion and malaise. If left untreated, symptoms can include jaundice and anemia and in some more serious cases seizure, kidney failure, coma and death. There is no current vaccine available, but people traveling to infected areas can take precautions. These include taking for four weeks prior to one’s sojourn into affected areas, either chloroquine, doxycycline or mefloquine chemoprophylactically. If malaria is contracted, the very drugs mentioned above or similar derivatives can be administered for supportive treatment. What’s used will be dependant on where the malaria was contracted.

West Nile Virus

An organism called a flavivirus causes the West Nile Virus. Found in mostly tropical and temperate regions, the West Nile Virus has been around for years. The CDC cites that the first cases in the United States were discovered in the vicinity around New York City in 1999. It’s believed that a mosquito bites an infected bird and then spreads the virus when it bites humans.

The severity of symptoms vary greatly. Many are bitten and infected, yet have no idea that they have been exposed to the disease. If symptoms occur these may include fever, headache, muscle ache, nausea, abdominal pain and a lack of appetite . People who get the more severe symptoms and consequences of the disease seem to have other concurrent risk factors present. These may include people with compromised immune systems, those who have undergone chemotherapy, have HIV, organ transplants or are pregnant. The elderly also seem more vulnerable, as well. More severe forms of the disease can lead to viral meningitis or encephalitis. There currently is no known cure for the disease. Treatment consists mostly supportive therapy.

Yellow Fever

The CDC confirms that the majority of Yellow fever occurs in Central and South America, as well as Africa. It is caused by an arbovirus from the family Flaviviridae and is spread usually by the Aedes aegypti mosquito. The virus incubates between three to six days and can have two phases. The first phase typically consists of muscle pain, fever, loss of appetite, nausea, vomiting and the shivers. Most people recover after this. Some, however, enter a second more toxic phase that can cause organ damage. Severe bleeding from the nose, mouth, eyes and stomach can occur. Kidney failure and eventual death usually follow. There’s no cure for yellow fever, but there is a vaccine available to prevent new infections. The vaccine is effective for approximately ten years and is important to those entering affected areas.

Mosquito-borne illness effects range from flu-like symptoms to potentially life-threatening complications. For the majority of disease entities, there is no cure. Mosquito control, vaccinations, chemoprophylactic therapy and common sense precautions are the key to controlling mosquito borne-illness transmission. Consultation with one’s physician is important prior to any travel or medication use.

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