Mosquito-borne illnesses are a growing threat: Know the symptoms and how to stay safe

The U.S. has seen an increase in mosquito-borne illnesses in recent years, and some of these infections can have serious side effects, such as coma, seizures and even death.

West Nile, dengue and eastern equine encephalitis (EEE) are some examples of vector-borne viruses. Vectors are insects such as mosquitoes, ticks and fleas and that spread illnesses or germs. If a person is bitten by a vector and becomes ill, it could be a vector-borne illness, according to the Centers for Disease Control and Prevention .

Since the diagnosis of the first human case of mosquito-borne eastern equine encephalitis in July − the first since 2020 − a portion of Massachusetts has been placed on high alert. Tuesday saw the first death this year of an man in New Hampshire who had been infected. West Nile virus cases also have increased; earlier this month, Dr. Anthony Fauci , former head of the National Institute of Allergy and Infectious Diseases, was hospitalized with the illness.

Mosquitos are the world's deadliest creature, according to the CDC . Here's a look at the how mosquito-borne illnesses spread.

How a virus spreads to humans

Most mosquitoes don’t carry disease. Those that do are called vectors. Vectors spread diseases such as West Nile virus, EEE, dengue fever, malaria and chikungunya in humans.

Since 2004, there has been a significant increase in the number of cases of vector-borne diseases, with more than 1 million cases documented in the U.S. between 2001 and 2023, according to the CDC's National Notifiable Diseases Surveillance System .

How a disease can travel long distances:

How a disease is transmitted :

Where mosquito-borne illnesses are a problem in the US

West Nile virus has been reported in 33 states. According to the CDC, there have been 289 cases in the U.S. this year; Texas has reported the most at 41 cases.

Dengue is less common in the U.S.; most illnesses occur among travelers returning home from trips abroad. So far this year, there have been 2,646 locally acquired cases: 16 in Florida, 2,551 cases in Puerto Rico and 79 in the Virgin Islands.

EEE is a rare disease that has been reported in five states this year, with one case reported in each state. This includes the death of the New Hampshire resident.

A person is more likely to contract a mosquito-borne illness in places with large standing bodies of water and areas experiencing significant outbreaks.

Symptoms of West Nile, dengue and EEE viruses

Mosquito-borne diseases can vary depending on the illness. Here's a look at how to differentiate these three vector illnesses:

Are there vaccines for mosquito-borne illnesses?

• There are no vaccines or medicines that prevent West Nile Virus.
• Two vaccines are available for dengue: Dengvaxia® (CYD-TDV), developed by Sanofi Pasteur, and Qdenga® (TAK-003), developed by Takeda.
• There are no vaccines or medicines to prevent eastern equine encephalitis.

How can people prevent mosquito-borne illnesses?

To protect yourself from vectors like mosquitoes, take these quick steps to ensure you and your family are safe from diseases these insects can carry.

The CDC recommends using " mosquito avoidance measures " when going outside, including:

• Using EPA-approved mosquito repellent on skin and clothes.
• Wearing long-sleeved shirts and pants, especially at night.
• Staying in well-screened areas.
• Sleeping under an insecticide-treated bed net when camping.

When traveling out of the country, especially to the Indian subcontinent, Southeast Asia or tropical South and Central America, consult your doctor.

CONTRIBUTING Eduardo Cuevas, Kinsey Crowley, Minnah Arshad and Jim Sergent

SOURCE Centers for Disease Control and Prevention, World Health Organization , National Institute of Health and USA TODAY research

This article originally appeared on USA TODAY: Mosquito-borne illnesses are a growing threat: Know the symptoms and how to stay safe