Growing up in Puerto Rico, I was used to seeing my arms and legs covered in mosquito bites after a full day at the beach. There was no escaping them as the sun began to set; it was almost a rite of passage — like it’s a toll you pay to experience the glorious hues of pink and orange across the sky.
What was once brushed off as a (mostly) harmless nuisance has become something you should pay closer attention to. As mosquito populations grow and climate patterns shift, doctors are seeing more people get seriously sick from diseases these tiny bugs carry.
“Both globally and in the US, we have seen increasing cases of mosquito-borne illnesses over the past decade,” says Dr. Scott Braunstein, chief medical officer at Sollis Health.
While not every mosquito bite will lead to a severe disease, it’s worth knowing the signs and how to protect yourself. According to Braunstein, here’s what to look for.
Did you know mosquitoes are the world’s deadliest animal?
Mosquitoes may be tiny, but they’re responsible for more deaths than any other creature on the planet. According to the World Health Organization, more than 700,000 people die each year from vector-borne illnesses that can be caused by parasites, viruses or bacteria. That includes everything from malaria and dengue to Zika virus, yellow fever, chikungunya fever and other viral infections that are difficult to treat once contracted.
Malaria alone caused nearly 600,000 deaths globally in 2023, mostly among children in Sub-Saharan Africa. Dengue affects roughly 390 million people annually, with around 20,000 deaths each year. And Zika virus, while rarely fatal, has been linked to severe congenital disabilities and neurological complications. Yellow fever, another mosquito-borne disease, can cause deadly liver failure in unvaccinated travelers.
These illnesses aren’t limited to tropical regions anymore. The viruses mosquitoes carry are expanding to new areas and reemerging in places they haven’t been seen in decades.
What are the most common mosquito-borne illnesses in the US?
If you’re in the US, the most likely mosquito-borne infections are West Nile virus and other types of encephalitis viruses (brain inflammation). Both can be mild, but in some cases, these infections can affect the brain and nervous system. Regarding travel-related cases, “Malaria, dengue and chikungunya are the most common,” Braunstein says. “In the last few years in the US, we have seen sporadic increases of locally acquired cases of malaria and dengue.”
When to worry about your symptoms
According to Braunstein, about 25% of people who get one of these illnesses from a mosquito bite will develop symptoms. The earliest signs tend to be subtle and flu-like: “most commonly fever, joint pain and headache.”
The more serious symptoms are harder to ignore and will require medical attention.
“If you begin to feel weak or dizzy, short of breath or develop neck stiffness or confusion, these could be signs of infection reaching your spinal fluid, and it’s critical to seek immediate emergency care,” Braunstein says.
Certain groups are more likely to develop severe illnesses, including children, older adults and people with compromised immune systems. Even your blood type can affect your likelihood of getting a mosquito bite. “People with Type O blood are the most attractive to mosquitoes, while those with Type A blood are the least attractive,” Braunstein adds. “Mosquitos are attracted to warmer body temperatures, sweat and dark-colored clothing.”
Not all mosquito bites are created equal, but they look the same
Identifying which mosquito bites are infectious from those that are not is where it starts to get tricky. You can’t tell from looking at a bite whether it’s harmless.
“Mosquito bites generally look and feel the same, whether the mosquito is carrying a serious disease or not,” Braunstein says. But if the area around the bite starts to swell rapidly, feels painful or shows signs of infection like pus or redness, that’s a reason to check in with your doctor. The same can be said for full-body symptoms like fever, joint pain or hives, especially if you have trouble breathing.
The size and severity of a bite relate to how your immune system responds to the saliva introduced by the mosquito when it bites.
Tips to avoid mosquito bites, according to a doctor
Here are some expert-approved tips to protect yourself from mosquito bites.
Avoid being outside during peak hours
The best way to protect yourself from mosquito-borne illnesses is to not get bitten in the first place. So your best bet is to avoid peak mosquito hours.
“To avoid being feasted on by mosquitoes is to avoid being outdoors at the time they are most active — dawn and dusk,” Braunstein says. If you do need to be outside, covering up matters: Wearing thick clothes, with long sleeves and pant legs, preferably lighter-colored clothing, can be protective.
Use a mosquito repellent
Regarding repellents, either DEET or a plant-based repellent be effective. “The main proven difference is that DEET provides longer-lasting protection (up to 5 hours), while plant-based repellants lose their efficacy quickly and require more frequent reapplication (every 1 to 2 hours),” says Braunstein. He notes that the American Academy of Pediatrics recommends no higher than 30% DEET for children. Insect repellents are also not recommended for children younger than 2 months.
Other mosquito repellent options you can consider:
Clean up your yard
One of the simplest ways to reduce mosquitoes in your home is to eliminate stagnant water. This includes flower pots, bird baths and pet water bowls, which should be cleaned and emptied frequently.
Braunstein says, “These small pools are ideal breeding grounds for mosquitoes, especially in warm weather.”
How to stay on top of outbreaks
If you want to stay ahead of outbreaks in your area, Braunstein recommends checking out ArboNET, a resource from the CDC that tracks mosquito-borne diseases across the US. The database includes human cases, infected mosquitoes and veterinary cases. I find it particularly helpful during travel or seasonal spikes.
One last myth to ditch
You’ve probably heard someone say mosquitoes prefer “sweet blood” or that people with diabetes are more likely to get bitten. According to Braunstein, that’s not how it works.
“People believe that mosquitoes prefer ‘sweet blood,’ for instance, after a high sugar meal or blood from those with diabetes,” he says. “However, it has been shown that mosquitoes actually prefer the blood of people without diabetes, blood type O and are more attracted to carbon dioxide, lactic acid and ammonia in our sewers.”
So no, it’s not your dessert they’re after. It’s your scent, sweat and carbon dioxide that attracts mosquitoes.
