Ultimate Guide to Mosquito Borne Diseases

Mosquitos, the #1 insect enemy! I guarantee that you wouldn’t want one as a pet. Why; because they are annoying, harmful to us, and are carriers of all types of diseases. Gross!

Unfortunately, they are global; but not to fear, the ultimate guide is here! Let’s investigate the major diseases, locations, and symptoms of mosquito borne illnesses, so that you can better avoid them, and enjoy nature in peace.


Malaria is caused by a parasite called plasmodium malariae being injected through the human skin. It’s spread by the female Anopheles mosquito, commonly known as the Marsh Mosquito. 

When the parasite enters your body, it will transition to your liver, where it will make base and lie dormant for weeks, months or years, then into your red blood cells; which is when the symptoms start to occur. 

Every year, approximately 210 million people are infected with malaria, and of the infected, 440,000 people tend to die from the disease. 

Fact: The mosquito obtains the parasite by feeding on a person that already has it.

Malaria can be found across the globe in tropical and subtropical climates where the air is warm and humid; areas such as South Asia, Africa, South and Central America, southern parts of the United States of America, Southeast Asia, and the Caribbean islands. 

High risk cases have been documented in areas of excessive heat such as African countries that are south of the Sahara Desert, New Guinea, the Dominican Republic, and Haiti. 

Symptoms of Malaria mimics that of the Flu, and tend to be:

  • Fever
  • Headache
  • Chills 
  • Muscle pain
  • Fatigue
  • Nausea or vomiting

In addition, sweating, abdominal or chest pain, or a cough will develop. If left untreated, this disease can cause severe complications such as breathing issues, Anemia, cerebral malaria, or organ failure. Based on the severity, antimalarial drugs are administered to relieve the symptoms.


Dengue is a viral infection that has caused a global incident, which has only increased within the past few decades. Because of this dramatic expansion, about half of the world’s population is now at risk.

It starts off with the virus family Flaviviridae that is transmitted by female mosquitoes of the Aedes aegypti and Ae. albopictus species. The virus has four distinct serotypes: DENV-1, DENV-2, DENV-3 and DENV-4; meaning that you could become infected up to 4 times with the same disease. 

It can be transmitted through human-to-mosquito contact, and mosquito-to-human interaction. Signs that you could be infected with Dengue start off latent, and build to flu-like symptoms such as:

  • Muscles and joint pain
  • Eye pain
  • Feeling nauseous and/or vomiting
  • Intense headache/fever
  • Reappearing rashes

These symptoms show up within 7 days of being bitten by a mosquito. In more severe cases, you could experience one of these more life-threatening illnesses:

  • Hemorrhagic Fever: affects the blood and causes significant inflammation.
  • Dengue Shock Syndrome: a severe form of Dengue.

Both of these illnesses are considered fatal if left untreated. 

Dengue can be found across the world, majorly in climates and countries located in the Americas, South-East Asia, Western Pacific, parts of Africa, and the Caribbean. 

These areas are significant because they are warm and rainy, with tropical features, which is the perfect breeding ground for the Aedes aegypti and Ae. albopictus species to grow and spread.

Since Dengue is a virus, there is no specific cure for the disease; however, some forms of interventions could decrease the rate and severity of the symptoms.

West Nile Virus

The West Nile Virus had its first breakout in 1937 in the West Nile region of Uganda; since then it has spread its way into Europe, and other major continents. This disease thrives in the subtropical, humid areas of Africa, West Asia, Middle East, and North America.

Similar to Dengue, the West Nile Virus is a mosquito borne disease carried by the Culex species of mosquitos. that is developed by the parasite flavivirus. Although fatal, 80% of mammals who have it show little-to-no symptoms until the infection matures.

The virus has a manifestation period of 3 days to 2 weeks, and can either be asymptomatic (no symptoms), or can fully develop into West Nile fever. Signs that are common to West Nile Virus are:

  • Swollen lymph glands
  • Headache/Fever
  • A skin rash on the torso of the body
  • Excessive tiredness
  • Muscle aches
  • Nausea/vomiting

Life-threatening neuroinvasive diseases such as West Nile encephalitis or meningitis or West Nile poliomyelitis may occur when the disease reaches adulthood. Symptoms present as:

  • High fever
  • Neck stiffness
  • Disorientation
  • Coma
  • Tremors or convulsions
  • Muscle weakness
  • Paralysis

Treatment typically involves hospitalization; and although there is no vaccine for humans, there is a West Nile virus vaccine for horses


Related to flavivirus family, Zika virus is a mosquito-borne illness that has been relevant to humans since 1952, and has had major outbreaks in Africa, the Americas, some Carribean islands, and Asia. 

It’s transmitted mainly by the Aedes aegypti species of mosquitoes.The virus is injected via feeding, and develops into maturation once it enters the bloodstream, and take 3 days to 2 weeks to reveal itself.

Symptoms of Zika can be mild, and last for 2 to 7 days, and can be a combination of the following:

  • Conjunctivitis
  • Rash
  • Fever
  • Muscle and joint pain
  • Headaches
  • Malaise (a general feeling of discomfort)

It can be transferred from mother to fetus, and is the cause of microcephaly, and other congenital illnesses. It has the potential to also ensure fetal loss, premature birth, as well as stillbirths.

 In adults and older children, further severe complications can also activate Guillain-Barré syndrome, neuropathy and myelitis. Currently, there is no treatment for Zika; however, there are prevention techniques.

Yellow Fever

Yellow fever has a significant history that is still affecting many humans to this day. Each year about 200,000 cases are documented, with around 30,000 deaths in 33 countries, which makes it a highly prevalent disease.

Aedes aegypti, and Haemagogus mosquitoes like the tiger mosquito are the carriers of the virus. This species is heavily populated in the Americas and in 32 countries in Africa, specifically Sierra Leone and Rwanda. In Latin America, 13 countries are also affected. Targeted countries tend to be:

  • Brazil
  • Colombia
  • Ecuador
  • Peru
  • Bolivia

Similar to other mosquito borne diseases, Yellow Fever is contracted via the Aedes feeding on an infected mammal (human or non-human). It has 3 transmission cycles:

  • Sylvatic: a jungle cycle that involves transmission between mosquito and non-human primates (e.g., monkeys)
  • Intermediate: viral transmission from mosquito to humans that live or work within jungle borders. It can spread from monkey to human, or from human to human.
  • Urban: commonly contracted by Aedes aegypti mosquitos in cities and towns. Humans who carry the disease are also a prime radiator of without even knowing it.

Signs and symptoms of Yellow Fever tend to appear quickly; within 3 to 6 days of exposure, and presents itself in acute symptoms, such as:

  • Muscle and joint aches.
  • Fever
  • Feeling flushed
  • Loss of appetite
  • Chills/shivers

More serious symptoms will reveal themselves as:

  • Heart rhythm problems
  • Lack of urination
  • Delirium
  • Abdominal pain
  • Bleeding from the eyes, nose, and/or mouth
  • Vomiting present with blood
  • Seizures

Like other mosquito based disease, no treatment is available, but there is a Yellow Fever vaccine that’s readily available by visiting your primary physician. 

Encephalitis Diseases

There are 4 major mosquito borne diseases that specifically attack the brain when it comes into contact with mosquito viruses: Japanese encephalitis, La Crosse encephalitis, St. Louis encephalitis, and Eastern Equine encephalitis.

Japanese Encephalitis

Japeanese Encephalitis is a rare, yet significant disease that is predominantly located in Asia. It is a viral infection that is spread via the bite of an infected Culex mosquito. This disease is only passed from mosquito-to-human, and it cannot transfer from person to person.

The risk of obtaining this illness is extremely low if you are outside of Asia; but increases depending on where in Asia you visit – like Japan, – the length of your visit, the time of year, and if you are visiting the rural areas. These factors double the chances of obtaining the disease.

You’ll know if you are infected with Japanese Encephalitis if you experience these symptoms:

  • Nausea/vomiting
  • Stiff neck
  • Spastic paralysis

The adverse brain symptoms of Japanese Encephalitis consist of deafness, uncontrollable emotions, and weakness on one side of the body; these symptoms are very fatal when developed in a child. There is a Japanese encephalitis vaccine that in inactive until it comes in contact with the virus.

La Crosse Encephalitis

With its origin in La Crosse, Wisconsin, La Crosse encephalitis  has radiated to its neighboring mid-western, southeastern states, and mid-atlantic states, and is prevalent within the United States. It’s postulated that 80-100 cases are reported each year in the United States.

La Crosse encephalitis is a viral, mosquito borne disease that is carried and transmitted by the Aedes triseriatus or the eastern treehole mosquito. It becomes infected by biting a forest animal that is infected, and then biting a human; the disease cannot be transferred from human to human.

La Crosse encephalitis typically present with no symptoms. If  they do occur, it happens within 5 to 15 days, and they are mild flu-like symptoms, which can develop into life-threatening symptom. Fatalities tend to happen in children and adolescents under the age of 16.

Mild symptoms usually include fever, headache, vomiting and lethargy (tiredness).

Severe symptoms include:

  • Inflammation of the brain
  • Seizures
  • Paralysis
  • Coma

Currently, there is no cure, preventative medicine or vaccine for this virus. In all cases, the best course of action is to take preventative measures for preventing mosquito bites.

St. Louis encephalitis

The mosquitos of the Culex are the carriers of St. Louis encephalitis, as they one of the dominant insects throughout the Gulf of Mexico, specifically Florida. The cycle of transmission is between the mosquito and the bird that it feeds on. 

Once the virus is in the Culex mosquito, it is passed on the eggs, which, in turn, infects the human. Luckily, this disease is not transferred from human to human. Living or visiting the southern, central, or western parts of the U.S. in the summertime, and elder age tend to increase the chances of contracting the disease.

Symptoms for St. Louis encephalitis can vary from non-existent and dormant, to mild or severe. If the symptoms do appear, they take the form of:

  • Stiff neck
  • Headache
  • Disorientation
  • Muscle and joint pain

Severe symptoms tend to be take the form of convulsions, stupor (unconsciousness), tremors, paralysis, and coma. The treatment for St. Louis encephalitis consist on managing symptoms, due to the fact that there is no specific treatment for the virus. 

Eastern Equine Encephalitis

Eastern Equine encephalitis is a rare and serious form of arborviruses, with only a few cases spanning over the previous decade. This is because the Aedes, Coquillettidia, and Culex species blood feed on small mammals that are in swampy areas, that humans tend to avoid.

The virus is prominent in freshwater swamplands located in the Atlantic and Gulf Coast states in the eastern part of North America, Central and South America, and the Caribbean.

Sometimes, Eastern Equine encephalitis symptoms may not appear; in other cases, they tend to expose themselves within 4 to 10 days of being bitten by a mosquito. They will take the form of headache, high fever, chills, and vomiting.

If left unchecked , these signs will develop further into disorientation, seizure, encephalitis, or coma. Children under the age of 15 and adults over the age of 50 are the most susceptible to acquiring the severe symptoms due to their possibly decreased immune system.

Currently, no treatment is available; supportive care from medical personal is the best option if treatment is necessary. Prevention tactics is the optimal choice for defending yourself against Eastern Equine encephalitis. 


Mosquito borne diseases are worldwide, and unfortunately haven’t been stopped. Be sure to take the proper precautions for protecting yourself against mosquito bites to prevent contracting one of these potentially fatal viruses.