Mosquito-borne virus can cause nerve damage

At the Laudick family in Greensburg, Indiana (USA), the members' lives were forever changed on August 5, 2013 when Leah Laudick (4 years old) told her mother, Shelly, that she suddenly felt strange feelings. very strong headache.

Two days later, Leah was admitted to a local hospital with a worsening headache and a slightly elevated white blood cell count. The baby slept soundly for most of the day and began to no longer respond to outside influences on August 9, 2013.

On the same day, the patient was quickly transferred to Peyton Manning Children's Hospital, Indianapolis (USA). It was here that Leah had her first seizure.

At this time, doctors could not determine Leah's condition. Tests for meningitis, typhus or herpes were all negative.

A day later (August 10, 2013), Leah's brain activity stopped. That night, the baby died in the mourning of the family.

It was not until several months later that the Laudics family received information from the US Centers for Disease Control and Prevention (US CDC) about a disease known as La Crosse. The disease appears after the patient is bitten by a mosquito. This is also the cause of Leah's death.

What is La Crosse disease?

La Crosse is the second most common mosquito-borne virus in the nation.

According to the US CDC, West Nile virus accounts for more than 90% of annual viral infections caused by mosquito or tick bites. In second place is La Crosse virus with about 2% of virus infections caused by mosquitoes or ticks each year (equivalent to 50-150 cases/year). Both children and adults can contract the La Crosse virus.

La Crosse virus, which is spread by mosquito bites, can affect the central nervous system.

La Crosse was first identified in the United States in 1960. Historically, most cases of this virus have been detected in the states of the Upper Midwest and Mid-Atlantic. Leah was the only case reported in Indiana in 2013.

The vast majority of cases are now occurring in the Southern Appalachian, stretching from North Alabama, Georgia, through East Tennessee and West North Carolina to Kentucky, Virginia and West Virginia.

The location of the cases has not yet been explained. However, many theories have been put forward around climate, land use, and mosquito species.

La Crosse is difficult to diagnose

La Crosse virus is carried and transmitted primarily by the hollow tree mosquito Aedes triseriatus, a local mosquito found throughout most of the eastern United States. The preferred habitat of this mosquito is places with hollow trees for female mosquitoes to lay their eggs, such as hardwood forests.

However, the virus can also be transmitted by two foreign and invasive species of mosquitoes: the tiger mosquito Aedes albopictus and the dust mosquito Aedes japonicus.

Tiger and dust mosquitoes are spreading across the United States in response to climate changes. They are also moved and spread from containers of water.

The team of researchers found them in the same habitats as the hollow tree mosquito, places with a lot of hardwood trees such as parks, cemeteries and backyards of residential areas. They also found these mosquitoes were present near documented cases of La Crosse.

All three species of mosquitoes grow in the same water source and get their food from mammals, including humans.

Diagnosing La Crosse disease is quite difficult because it is easy to confuse when the symptoms are quite similar to the flu. The only way to diagnose La Crosse disease is to send a blood and cerebrospinal fluid sample to a health care provider for testing.

One problem with this pathology is that patients with La Crosse infection are often concentrated in densely populated communities for many years.

For example, of the 115 cases reported in Tennessee since 2011 to date, most have occurred in some small county in the state. So when some cases are diagnosed, local doctors and leaders may know the virus is present in their area.

Symptoms of La Crosse

Cases of La Crosse usually begin with fever, fatigue, vomiting, and headache. This condition lasted for almost 2 weeks. Most people infected with the virus make a full recovery.

However, like West Nile disease, La Crosse is potentially neuroinvasive, meaning it can invade and affect the central nervous system.

Research shows that age, immune system and virus strain are important factors in the course of La Crosse disease. On the other hand, the delay in hospitalization and emergency treatment also affects the severity of the disease.

The most susceptible people are the immunocompromised group and children. According to reports, more than 60 children each year are diagnosed with La Crosse disease. Severe cases are usually discovered in the hospital after the patient has a seizure, coma, unilateral paralysis, or altered mental status.

Severe La Crosse can lead to long-term nerve damage. The number of people who die from this virus infection is very rare. However, neurological and behavioral effects may occur after resolution, including cognitive disturbances, a diagnosis of hyperactivity disorder, attention deficits, and decreased IQ scores.

La Crosse disease prevention

Until now, scientists continue to recommend that people should prevent mosquito bites from the beginning to avoid infection before La Crosse.

Mosquito scents or mosquito repellent products such as creams can effectively prevent disease.

Another measure is to limit the ability of mosquitoes carrying the La Crosse virus to breed locally. This requires people to remove outdoor water containers such as potted plants, bottles, etc. These can simulate the conditions of a forest and facilitate mosquito breeding.

Mosquitoes that carry the La Crosse virus have also been found to breed in tires containing water. Therefore, we can drill drainage holes on the tires to limit this situation.

Another strategy to help prevent this disease is to try to avoid mosquito bites by all means when indoors during peak mosquito hours, usually early evening.

Specifically, using products such as mosquito scent, wearing light-colored clothing, and applying mosquito repellent can help prevent mosquito bites.