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Mosquito-borne illnesses can spell trouble for summer

Lankenau Medical Center August 16, 2017 General Wellness

Summer is a time to enjoy the outdoors but, in doing so, you’ve likely earned yourself a few bug bites. While these bites might sting and scab, they’re just another part of the summer routine. However, in countries across the world, bug bites can be more than just an itch to scratch.

“Mosquitoes are the primary carriers for some of the most debilitating—and potentially fatal—diseases across the world,” says Lawrence Livornese, MD, infection prevention specialist and Chairman of the Department of Medicine for Main Line Health. “While we’re fortunate that these rarely impact North America as much as they impact some other countries, international travel has made it easier for mosquito-borne illnesses to spread.”

If you’re planning summer travel this year, and even if you’ll be staying close to home, Dr. Livornese offers some insight into the mosquito-borne illnesses you should be aware of—even as the days of summer come to a close.

Yellow fever

Yellow fever, which is found primarily in Africa and South America, is far less common today than in earlier decades. If you’re traveling to one of these areas, however, you can get vaccinated for yellow fever and residents who are traveling from these countries to other areas are required to show proof of vaccination. These steps have helped to greatly reduce the spread of the virus.

If you haven’t been vaccinated, but have recently visited one of these areas, keep an eye out for telltale yellow fever signs like fever, headache, body pain, nausea, vomiting and fatigue. In severe cases, symptoms may progress to jaundice, renal failure and a high fever.

Although there is no specific treatment, cases among US travelers are extremely rare due to a highly effective vaccine and the requirement for vaccination.

West Nile Virus

West Nile Virus (WNV) is relatively well-known in North America, but can also be found in Africa, Europe, the Middle East and West Asia. While the virus is spread to humans through a bite from an infected mosquito, the virus originates with an infected bird or horse. These are host animals, and mosquitoes contract the virus after biting them.

Although WNV is common, 75 percent of those who are infected with it will exhibit mild or no symptoms. Those who do exhibit symptoms will experience fever, muscle pain, headache, abdominal pain, rash and vomiting. A minority of those infected may develop severe neurologic involvement.

No vaccine is available for WNV, but you can take preventative measures to protect yourself from this virus. WNV occurs more frequently in the late summer months, including early September, so be extra cautious about mosquito protection during this time. And, if you live on or near farmland, inquire about a WNV vaccine for horses, which is available.


Dengue, the leading mosquito-borne illness, is transmitted by mosquitoes that are infected with the viral disease. In recent years, it has been on the rise in several countries but remains primarily in Africa, Central and South America, the Caribbean, the Eastern Mediterranean, South and Southeast Asia and Oceana.

Those who suffer from dengue’s symptoms might liken it to the flu, but more severe. Dengue is marked by a fever that is accompanied by two or more of the following symptoms: severe headache, pain behind the eyes, muscle pain, nausea and vomiting or a rash. A small percentage of those who contract dengue will be diagnosed with dengue hemorrhagic fever, which is marked by very severe symptoms like black stool, pale and bruised skin, excessive thirst, vomiting blood and bleeding from the nose, mouth or gums.


Chikungunya is prevalent in Africa, Asia and the Indian subcontinent, but has been identified in more than 60 countries, including North America. The virus is transmitted via the bites of infected mosquitoes.

Like dengue and Zika, chikungunya is marked by symptoms like fever, joint and muscle pain, headache, nausea, fatigue and a rash. However, unlike dengue and Zika, most people who are infected with chikungunya will exhibit symptoms.

While chikungunya symptoms can be treated, those who are diagnosed with the virus often continue to suffer debilitating joint pain that can last for several weeks or months. Currently, no vaccine is available for chikungunya. However, trials are underway at the National Institute of Allergy and Infectious Diseases to develop a vaccine for this virus.


Zika, the mosquito-borne illness that grabbed headlines in 2016, has been reported on the continents of Africa, the Americas, Southeast Asia and the Western Pacific. In addition to being spread by infected mosquitos, Zika can also be spread through sexual transmission between partners.

Although most people with Zika do not experience symptoms, those who do will still experience relatively mild ones—including a low-grade fever, rash, conjunctivitis, muscle and joint pain and headache.

Following a Zika outbreak in 2016, research found that infants born to women who had contracted the Zika virus were at a much greater risk for congenital brain abnormalities and Guillan Barre syndrome can occur in women who are diagnosed with Zika. For this reason, women who are pregnant or considering pregnancy are urged to talk to their doctors about traveling to an area where Zika may be prevalent.

Like chikungunya, there is no vaccine currently available for Zika. However, several vaccines are currently in development or being trialed to help address this growing public health concern.


Malaria is a risk for nearly 50 percent of the world’s population, but the majority of cases and fatalities as a result of malaria occur in Africa, Southeast Asia, Latin America and the Middle East. However, according to the World Health Organization, 91 countries and areas had ongoing malaria transmission.

The symptoms of malaria—a fever, headache and the chills—can be mild and difficult to recognize. However, if you’ve been to an area where malaria is prevalent, it’s important to be aware of these symptoms. Once they progress to severe, often within 24 hours, the risk of death increases.

There is good news: Malaria is preventable and curable. If you’re traveling to an area where malaria is prevalent, inquire about mosquito nets that have been treated with insecticide, as well as whether or not your residence will be sprayed with insecticide prior to arriving.

Prevention of mosquito-borne illnesses

The best way to protect yourself from mosquito-borne illnesses this summer? Talk to your doctor.

“If your vacation plans include international travel, talk to your doctor about what vaccinations you and your family may need or what preventative steps you can take to protect yourself from mosquito-borne illnesses or other illnesses,” says Dr. Livornese.

And, if you’re stateside this summer, continue to cover up using products like DEET or Picaridin insect repellent, which have been shown to be the most effective in repelling mosquitoes.

Whether you are traveling for business or pleasure, our travel health experts can provide itinerary specific health and safety education, as well as recommend the appropriate immunizations for your destination based on recommendations and requirements from the Centers for Disease Control and the World Health Organization.

To schedule an appointment with a infectious disease or travel health specialist at Main Line Health, call 1.866.CALL.MLH (1.866.225.5654) or use our secure online appointment request form.