How much do you know about Viral Encephalitis? Brush up on the facts before you become another statistic

The Encephalitis virus appears in many forms and causes severe inflammation which can result in brain hemorrhage.

Some forms of viral Encephalitis are hosted by ticks, although it's mainly a mosquito transmitted disease.

Mosquitoes infect humans and animals with the virus as they feed on the victim’s blood.

There are three varieties of pests that can cause human viral Encephalitis; Togaviridae, Flaviviridae and Bunyaviridae.

With an increase of mosquito infestations worldwide, the spread of viral Encephalitis has increased and affects 150-3,000 people per year.

Statistically, the risk of viral Encephalitis infection focuses mainly on the elderly and young children. The virus occurs more frequently in low-income areas.

Types of Encephalitis

The Encephalitis virus is classified in seven distinct types, including:

• St. Louis (SLE)
• West Nile (WNE)
• Japanese (JE)
• La Crosse (LCE)
• Eastern Equine (EEE)
• Western Equine (WEE)
• Venezuelan Equine (VEE)

The most frequently occurring strains of Encephalitis are recorded as: SLE, WEE, VEE, and EEE.

The most deadly form of this virus is EEE, which has a death rate of 30%, while SLE only claims 5%.

Encephalitis is also transmitted through deer ticks. This variety is classified as Powassan (PE), and has a mild occurrence compared to mosquito transmitted Encephalitis.

Other mosquito hosted viruses include Yellow Fever, Malaria, Dengue Fever and Rift Valley Fever.

St. Louis Encephalitis

The history of St. Louis Encephalitis (SLE) can be traced back to 1964. Since that time, SLE has infected 4,437 people, with a fatality rate ranging between 5-15%.

SLE is the most common form of Encephalitis in the United States, creating epidemics in the Midwest and Southeast areas of the country.

A mosquito hosted disease, SLE infects 193 people per year, on average. The cycle is perpetuated through the following species of Culex (Cx) mosquitoes:

• Cx. nigripalpus
• Cx. pipiens
• Cx. quinquefasciatus
• Cx. tarsalis

Although the severity and the symptoms of SLE vary, it seems to hit elderly people and young children the hardest. Causing such ailments as headaches and meningoencephalitis, SLE may cause inflammation in the spinal cord and brain.

West Nile Encephalitis

Much like SLE, West Nile Encephalitis (WNE) is spread primarily through the Culex species of mosquitoes.

Secondarily, Aedes and Anopheles species have also been known to carry WNE, transmitting the disease from infected birds.

First discovered in Uganda in 1937, WNE has spread throughout the world. WNE cuased epidemics during the 1950’s in Israel, and in Europe in the 1960’s. West Nile Encephalitis gained the attention of the world during a South African epidemic in 1974, which devastated the population.

The first cases of WNE in the United States broke out in New York in the early fall of 1999. The increase of international travel and the trade of exotic birds are likely causes.

West Nile Encephalitis can be a painful and deadly virus, infecting humans and animals alike. Before you travel, be aware of high-risk WNE areas like:

• Africa
• Europe
• Middle East
• Western Asia

Japanese Encephalitis

Japanese Encephalitis (JE) is most common throughout Asia, but has affected other parts of the world as well.

The life cycle of a mosquito perpetuates the spread of this virus. JE is spread to mosquitoes either through the fertilization of eggs, or from feeding off an infected pig.

Mosquito populations increase with the low-maintenance of warm, stagnant areas of water. In Japan, rice fields are the main source for mosquito breeding.

Infecting 45,000 people per year, Japanese Encephalitis is at serious risk of creating epidemics.

If you are traveling to Japan, or the Pacific, take necessary precautions. Here’s a look at the symptoms of JE:

• Sudden fever
• Headache
• Vomiting

The symptoms of JE will not show themselves until 1-2 weeks after the initial infection. In most cases, the virus should pass through your body in one week unless it advances into a more serious condition.

La Cross Encephalitis

La Crosse Encephalitis (LCE) threatens the health of the entire United States. Although the first cases appeared in Wisconsin in 1963, the virus has spread to areas that include:

• Iowa
• Ohio
• Illinois
• Indiana

Presently, of the average 75 reported cases of LCE per year, many have appeared in the mid-Atlantic and Southeastern areas as well.

La Crosse Encephalitis is classified as a Bunyavirus, which perpetuates during the summer months in the United States. Each year the LCE cycle begins when Adedes triseriatus mosquitoes contract the virus from tree squirrels and chipmunks.

Mosquitoes feeding during the day infect humans, especially children under 16, with the virus.

The initial symptoms of La Crosse Encephalitis are very similar to the flu; fevers, headaches and nausea accompanied by a loss of energy. If LCE progresses, lingers or becomes more serious, patients may experience seizures, coma, paralysis and neurological dysfunction.

The occurrence of death from La Cross Encephalitis is extremely rare, affecting less than 1% of those infected.

Eastern Equine Encephalitis

Eastern Equine Encephalitis (EEE) is a deadly alphavirus, claiming the lives of two thirds of those who are infected.

Complete recovery from EEE is difficult, as it often causes permanent brain damage in patients.

Since the first discovery of EEE in the 1930’s, the virus has caused illness in areas along the Eastern coasts of the Gulf and beyond. In the United States, EEE has affected a small portion of the Midwest.

There are a couple of mosquito species that spread the virus, like:

• Ae. vexans
• Culex nigripalpus

These mosquitoes can transmit EEE to humans, horses, pheasants, quail, the ostrich, emus and puppies.

Take extra precautions during late spring and summer, as this is when EEE is typically transmitted. Wear protective clothing and use mosquito netting when camping. Avoid swampy areas where mosquitoes breed.

Western Equine Encephalitis

Western Equine Encephalitis (WEE) emerged in the 1930’s in California. Today, WEE is found throughout the American continent, including the United States, Canada, and Mexico.

Sharing commonalities with Eastern Equine Encephalitis, WEE is also an alphavirus, which is transmitted to humans and animals through mosquitoes.

WEE has a lower mortality rate than EEE, causing death in only 3% percent of patients.

Following a short incubation period, you will develop flu-like symptoms if you have been infected with Western Equine Encephalitis.

If the virus develops into a more serious stage, you may also suffer from the following effects: changes in mental patterns, anorexia, malaise or meningeal irritation.

The origins of the virus can be found in the following species:

• Mosquitoes
• Mammals
• Passerine birds

Birds and mammals may carry the virus, but mosquitoes are responsible for infecting humans.

A few different species of mosquitoes carry WEE, including: Domestic mosquitoes, Cx. tarsalis, Adedes dorsalis, Aedes melanimon, Ae. campestris.

In California, the mosquito species Aedes melanimon are the prime carriers of Western Equine Encephalitis, while Ae. campestris dominates the Utah and New Mexico areas.

Venezuelan Equine Encephalitis

Venezuelan Equine Encephalitis (VEE) is also classified as an alphavirus, as it can infect both humans and animals on an epidemic scale.

In fact, VEE is responsible for an epizootic attack in South America in 1969. An epizootic is when large populations of animals, like horses, are wiped out by a disease.

Today in Central and South America, equine vaccination programs are still a top priority, as a way to control the spread of VEE in animals.

Although less severe, VEE can impact human life as well. For instance, there were 90,000 VEE infections alone in Venezuela and Columbia during the fall of 1995.

Venezuelan Equine Encephalitis originates in heavily forested areas where mosquitoes breed. The mosquito species Culex melanoconion contract the disease from rodents, only to pass VEE on when they feed.

Conclusion

Although the symptoms of Encephalitis can vary from differing types, the effects have many flu-like qualities.

If you suspect that you have Encephalitis, contact your doctor immediately. In most cases, a blood test will help to determine if it’s Encephalitis.

You can work to combat Encephalitis by taking a few practical precautions. For instance, if you are traveling to an infected area, take some time to research the mosquitoes feeding schedule.

Except for Japanese Encephalitis, there are no human vaccines for this disease. If you become infected, there are a few medical measures that can be taken to prevent brain swelling, lung collapse and secondary bacterial infections.

Read the rest of this site for more information on mosquito hosted diseases like Malaria, Yellow Fever, Dengue Fever and the West Nile Virus. Find out more on preventing mosquito bites with this easy to read online guide.