8 Illnesses You Can Get From a Bugbite

How to prevent transmission, plus what to do if you are bitten

Kristen Fischer,

AARP

Comments

Published June 05, 2026

A resting adult female Aedes aegypti mosquito, also known as the yellow fever mosquito

An Aedes aegypti mosquito, also known as the yellow fever mosquito

Smith Collection/Gado/Getty Images

Key takeaways

Mosquitoes, ticks and fleas can be infected with viruses, bacteria and the like and transmit them to humans.
Some illnesses that you can get from insects cause long-lasting complications, while others can be severe, especially for older adults.
Knowing which insects are a problem in your area and taking steps to prevent bites is important.

Some bugbites are more than just itchy — they can make you seriously sick. And in warmer months, your risk of getting an insect-borne illness from mosquitoes, ticks, fleas and other bugs rises.

While trends can ebb and flow, there’s “absolutely” an uptick in insect-borne diseases, says Dr. Beth Kirkpatrick, an infectious disease doctor at the University of Vermont Medical Center. According to the Centers for Disease Control and Prevention (CDC), cases more than doubled between 2001 and 2023.

Also growing: the threat of getting bitten by an insect carrying multiple, different disease-causing germs. An Ecosphere study that came out in 2025 showed that approximately 1 in 10 juvenile deer ticks in the Northeast U.S. carry two or more different disease-causing pathogens.

Why bugbites — and diseases from them — are rising

Climate change has helped fuel the rise in insect-borne diseases. Milder winters, for example, allow more ticks to survive the colder months than have in the past. But climate isn’t the only factor: A lot of it has to do with other ways that humans have modified the environment, says Jonathan Oliver, an associate professor in environmental health sciences at the University of Minnesota School of Public Health.

Changing land-use patterns have led to booming mice, deer and chipmunk populations in suburban areas, the CDC explains, and these animals harbor ticks. What’s more, global travel can introduce insect-borne illnesses not often seen in the U.S., such as chikungunya and Zika.

8 diseases you can get from a bugbite

Here are eight of the more common diseases transmitted by insects.

A blacklegged tick, also known as a deer tick.

Robin Loznak/ZUMAPRESS.com/Alamy Live News

1. Lyme disease

Lyme disease is the most common insect-borne disease in the U.S. You can get it if you’re bitten by a deer tick (also known as a black-legged tick) that’s infected with the bacteria Borrelia burgdorferi.

In the past 30 years or so, the geographic range of deer ticks has expanded. They used to only be found in the northern parts of the U.S., but they now exist in the Midwest, Oliver says. The proportion of infected ticks has also grown, he notes. In April, emergency room visits for tick bites were up more than 25 percent from a year ago, according to the CDC. In 2023 there were more than 89,000 cases of Lyme disease in the U.S. Other estimates say that about 476,000 people are diagnosed and treated for Lyme disease each year in this country.

Where is it? You can encounter Lyme disease throughout the U.S., but it’s more commonly found along the Eastern Seaboard and in the Great Lakes region.

Symptoms: Sometimes you’ll see a bull’s-eye rash at the site of the bite in three to 30 days. Other early symptoms of Lyme disease include headache, fatigue, swollen lymph nodes, stiff joints, muscle aches and fever.

Diagnosis: Lyme disease is diagnosed with a blood test.

Treatment: Most cases of Lyme disease can be treated with antibiotics, and people who take antibiotics early in the disease course typically recover quickly and completely, the CDC says. Some people will experience lingering symptoms like fatigue or pain — something called post-treatment Lyme disease syndrome.

Currently there is no vaccine to prevent Lyme disease. However, that could change. In March, Pfizer and specialty vaccine company Valneva announced that its phase 3 trial for a Lyme disease vaccine showed about 70 percent efficacy. It requires multiple doses but could be a good option for those at high risk for the disease, Kirkpatrick says.

A Culex pipiens mosquito.

Martin Leleievre/AFP via Getty Images

2. West Nile virus

West Nile virus is the most common mosquito-borne disease in the U.S., with diagnoses peaking in late August and September. Infected culex species mosquitoes can pass it on to humans. Humans, however, don’t develop high levels of the virus and, therefore, can’t pass it on to other mosquitoes.

In 2025 there were 2,076 cases of West Nile virus in the U.S. One in 5 people get sick when an infected mosquito bites them, but those over the age of 65 tend to get more severely sick from the disease and are three times more likely to have a neurological illness compared with younger demographics, the CDC reports.

Where is it? West Nile virus has been found nationwide, with the exception of Hawai‘i and Alaska.

Symptoms: The virus can cause flu-like symptoms, which can start two to six days after a bite by an infected mosquito or up to 14 days post-bite. If you have a weakened immune system, it may take longer for symptoms to develop. About 80 percent of infected people don’t have symptoms, the CDC reports.

Diagnosis: West Nile virus is diagnosed with a blood test or a cerebrospinal fluid (spinal tap) test.

Treatment: There are no specific medicines available to treat West Nile virus; the CDC says rest, fluids and pain medications may relieve some symptoms. Fewer than 1 percent of people develop severe illness that could impact their central nervous system, require hospitalization or cause death.

Most Popular

3. Anaplasmosis

Anaplasmosis is spread by infected deer and western black-legged ticks carrying Anaplasma phagocytophilum bacteria. About 5,000 to 6,000 people get anaplasmosis every year in the U.S. Adults over 50 have a higher risk of becoming seriously ill from it, the Cleveland Clinic reports.

Where is it? Most people encounter anaplasmosis in the northeastern and upper Midwestern U.S. Though you can get anaplasmosis any time of year, it’s most common in June, July, October and November, when black-legged ticks are most active.

Symptoms: Symptoms of anaplasmosis usually start within one to two weeks after the bite and include fever, chills, nausea, vomiting, headache, diarrhea and loss of appetite. Without treatment, people can experience additional symptoms like confusion or seizures.

Diagnosis: A diagnosis can be made with a culture from blood or another body fluid.

Treatment: Early intervention with an antibiotic can prevent death and severe illness. People who start taking antibiotics soon after symptoms begin should feel better within 24 to 48 hours, according to the Cleveland Clinic.

A tiger mosquito, or Aedes albopictus.

Christophe Geyres/Abaca Press/Alamy Live News

4. Dengue

About 1 in 4 people who contract the dengue virus from an infected Aedes albopictus or Aedes aegypti mosquito will become sick from it; about 1 in 20 will become severely ill or die from it. While dengue is still considered rare, cases are going up in the U. S. In 2024 there were 3,483 cases among U.S. travelers, up 84 percent from the previous year, and the total of cases reported was 359 percent higher than the annual average from 2010 to 2023, the CDC reports. From 2010 to 2025 there were 61,215 cases in the U.S.

“I think it’s going to continue creeping forward, but I don’t think we’re going to see a massive outbreak here because we have pretty good public health control … and there’s pretty good surveillance,” Kirkpatrick says.

Dr. Kirsten E. Lyke, a professor of medicine and codirector of the Malaria Research Program at the University of Maryland School of Medicine, is more concerned.

“I kind of feel that dengue is one of our biggest threats, because by and large, we haven’t had dengue in the U.S.,” she says. Prediction models indicate it’s going to move from the Deep South up to the mid-Atlantic.

In a 2019 study in Nature Microbiology, researchers estimated that in five to 15 years human travel and migration would be the largest factors accelerating the spread of mosquitoes. Climate change and growing urbanization would be responsible for establishing new mosquito habitats, the authors of the study wrote.

Aedes mosquitoes can thrive in urban environments and don’t need a lot of water, which could make dengue difficult to contain, Lyke notes. The mosquitoes that carry it bite in the daytime, she adds, whereas most mosquitoes bite primarily at dawn and dusk.

An Aedes aegypti mosquito.

Smith Collection/Gado/Getty Images

Where is it? Dengue has been reported in the 49 continental states, but most cases are restricted to people who have traveled outside the country, according to the CDC. Aedes mosquitoes are common in our country, so local spread of dengue is possible, though widespread transmission is low, the CDC notes.

Symptoms: Symptoms of dengue can include fever, pain behind the eyes, and muscle, joint or bone pain. Nausea, vomiting and rash are also signs of illness. Severe symptoms include vomiting three times in 24 hours, bleeding from the nose or gums, vomiting blood and belly pain, the CDC reports.

Diagnosis: A blood test can diagnose dengue.

Treatment: There’s no specific medicine for dengue; doctors typically just treat symptoms, and most people recover. Other countries offer vaccines, which may be a future possibility in the U.S., Kirkpatrick notes.

An American dog tick.

Carolyn Kaster/AP Photo

5. Rocky Mountain spotted fever

Several kinds of ticks — including the American dog tick, the brown dog tick and the Rocky mountain wood tick — spread this bacterial disease, which can be serious and even fatal if left untreated.

Where is it? The ticks that spread this disease are present throughout most of the continental U.S.

Symptoms: Symptoms of the disease can include fever, headache, rash, stomach pain, muscle pain and loss of appetite.

Diagnosis: Blood tests can diagnose Rocky Mountain spotted fever, but results can take weeks, so your doctor may prescribe antibiotics before results come in. A skin punch, or sample, can also confirm a diagnosis.

Treatment: The infection can spread rapidly, so treating it with the antibiotic doxycycline within the first five days of symptoms is vital. Most people find relief with antibiotics, but waiting too long to get treated can cause complications like hearing or vision loss, nerve damage or neurological issues like vertigo.

6. Zika

The Zika virus was discovered in the late 1940s, but the 2015–16 outbreak in Brazil and the U.S. thrust it into the mainstream due to fears about it spreading to the babies of pregnant women. (The infection is associated with a birth defect called microcephaly.) Last year there were no locally acquired cases.

The virus is transmitted when a person is bitten by an infected Ae. aegypti or Ae. albopictus mosquito. Sexual transmission can also occur.

Where is it? Since 2018, there have been no reports of Zika virus transmission by mosquitoes in the continental U.S., according to the CDC. Previously, a handful of locally acquired cases were reported in Florida and Texas.

Symptoms: Symptoms of Zika are typically mild and include headaches and joint pain. Approximately 80 percent of people infected with the Zika virus don’t have symptoms, the CDC reports.

Diagnosis: A blood or urine test can diagnose Zika.

Treatment: Symptoms are often treated with over-the-counter medications.

A lone star tick.

Smith Collection/Gado/Getty Images

7. Alpha-gal syndrome

If you’re bitten by a tick (primarily a lone star tick) that’s infected with a sugar molecule known as alpha-gal, you can develop a food allergy to red meat — a phenomenon known as alpha-gal syndrome. The molecule is found in mammals (and ticks) but not humans.

A 2023 CDC report estimated that as many as 450,000 people in the U.S. might have been affected by alpha-gal syndrome since 2010. In addition to the lone star tick, the black-legged tick and the western black-legged tick can spread this disease.

Where is it? The ticks that carry alpha-gal are largely in the southern, central and eastern parts of the country.

Symptoms: Symptoms of alpha-gal include hives, rash, feeling lightheaded, facial swelling and shortness of breath. Nausea, diarrhea, vomiting and stomach pain are common, too. Some people have serious allergic reactions. Symptoms don’t come on right away and may take hours to show up after eating. If you have trouble breathing, have a fast pulse or feel dizzy, seek emergency care.

Diagnosis: A blood or skin test can tell you if your symptoms are alpha-gal syndrome.

Treatment: Upon diagnosis, many people can’t eat foods with alpha-gal in them, such as beef, pork and lamb. For some, the allergy eventually goes into remission.

A blacklegged tick, also known as a deer tick.

CDC via AP Photo

8. Babesiosis

You can develop this illness — nicknamed “American malaria” — if you’re bitten by a deer tick with the babesia parasite. It infects and kills red blood cells, similarly to malaria.

Babesiosis is similar to Lyme disease, but usually doesn’t cause a rash. The microbe behind the disease — Babesia microti — is most commonly found alongside the bacterium that causes Lyme disease.

Where is it? You’ll find babesiosis in the Northeast, upper Midwest and sometimes in the Northwest.

Symptoms: Symptoms can include high fever, low appetite, sweating and muscle or joint pain and can take weeks or months to develop. People over 50 may get a lot sicker from this, especially if they no longer have a spleen, which clears out infected cells, Kirkpatrick explains. Babesiosis can lead to a form of anemia.

Diagnosis: The illness is diagnosed by a blood test.

Treatment: Doctors typically treat babesiosis with a combination of medications, which may include antiprotozoals, antibiotics and antimalarial drugs. Blood transfusions can be used in severe cases.

Effects on older adults

Different illnesses affect individuals of different ages to different extents, Oliver says.

One thing to keep in mind: It’s harder to fight off infections as you get older. That’s because your immune system weakens with age. Chronic conditions common among many older adults can also diminish your ability to fight an infection, Kirkpatrick says.

That’s why prevention is so important for older adults. “All of these diseases are a lot easier to prevent than to treat,” Oliver says.

Preventing bug-borne diseases

A few tips to stay protected when you’re outdoors:

Wear long shirts and pants .
Apply insect repellent. Use a product like permethrin on clothing; on skin, use picaridin or a repellent with 30 percent DEET or less.
Check yourself after you’ve left the area.
Cut grass around your yard regularly; tall grass creates a welcome home for critters.
Protect your pets with collars or medications.
Remove any ticks promptly.
Take a shower immediately after you come inside.

Pay attention to alerts from your local and state health departments, as they will know which bug-borne pathogens are the biggest threat in your area, Kirkpatrick advises. If you are bitten and start to feel off or experience specific symptoms, be sure to alert your doctor.

While the thought of getting bitten may be overwhelming for some people, Lyke says prevention measures can give you peace of mind. “Don’t use that as an excuse to not go out and do things,” she adds.

%{postComment}%

Kristen Fischer is a contributing writer at AARP based at the Jersey Shore. She has also written for Health, WebMD, and McKnights and is the author of Zoo Zen: A Yoga Story for Kids.