Differentiating Between Mosquito-Borne Diseases: The Key to Prevention

Mosquitos can transmit different diseases. So how can you tell which one is the cause of your illness? Knowing the mosquitos that are more common in your travel destination and taking stock of your symptoms can help your doctor narrow down the disease you have. Depending on the type of disease, a correct diagnosis can be crucial for prompt treatment and prevention of further transmission of the infection. There are many mosquito-borne infections around the globe, in this blog post we will focus on the four diseases that are most relevant for travelers.

Differentiating Between Mosquito-Borne Diseases: The Key to Prevention

Travel Clinic UZH
10 September, 2024

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Identifying and Treating Mosquito-Borne Diseases

While there are many differences between the following four diseases, there are also similarities. Since they are all transmitted by the bite of an infected mosquito, they are most common where mosquitos are abundant as it is typical in tropical and subtropical regions.

In the following paragraphs, we will focus on the symptoms and treatment of these four diseases.

Dengue

Dengue is a viral infection of which around half the world’s population is at risk of. It is most often transmitted by the Aedes aegypti mosquito (also known as yellow fever mosquito). In 2023, a surge of local dengue transmission by Aedes albopictus (tiger mosquito) began in Europe (France, Italy, and Spain).

Many dengue infections present without symptoms or only mild illness that can include the symptoms high fever, pain behind the eyes, severe headache, nausea, vomiting, muscle and joint pain, and a skin rash. These symptoms typically begin 4-10 days after infection and last for 2-7 days.

While rare in travelers, dengue can become severe, which is more common in those who are infected a second time. Therefore, tourists present rarely with sever dengue. Initially the symptoms present as in mild dengue. Around day 4 or 5, usually after the fever has subsided, the condition worsens again. Typical symptoms of severe dengue include fatigue, low blood pressure, pale and cold skin, shortness of breath, abdominal discomfort, nosebleed, skin or mucosal hemorrhages, blood in vomit or stool. Particularly severe cases may result in life-threatening shock.

There is no specific treatment for dengue—instead, treatment centers on managing symptoms. Patients with severe dengue require hospitalization, some even intensive medical care.

Qdenga® is a new vaccine that is licensed in Switzerland and many other European countries. It is only recommended for travelers aged six years or older who have already had a dengue infection more than 6 months ago and are planning a stay in a region with significant dengue transmission.

Zika

The Zika virus is primarily transmitted by the Aedes mosquitos, which mainly bite during the day. People who become infected are often asymptomatic. If symptoms occur, they are typically mild and include fever, rash, muscle and joint pain, conjunctivitis, headache, and malaise.

So far there is no vaccine and no specific treatment for Zika available — management of the disease is primarily supportive, i.e. focusing on symptom relief.

Zika poses a considerable risk for pregnant women respectively their unborn child as an infection can lead to malformations. Pregnant women, as well as people and couples planning a pregnancy, are advised not to travel to areas with an increased risk for Zika transmission.

Malaria

Malaria is caused by a parasite called Plasmodium that is primarily spread through infected Anopheles mosquitos. This mosquito bites almost exclusively between sunset and sunrise. Five Plasmodium species cause malaria in humans, two of them—P. vivax and P. falciparum—present the greatest threat.

The initial symptoms of malaria can be mild and difficult to recognize as malaria. However, if left untreated, some cases can progress to severe illness and death.

Currently there is no vaccination against malaria available for travelers. So far there are two malaria vaccines licensed for young children in regions with high to moderate malaria transmission, particularly sub-Sahara Africa, conferring a partial protection against the disease. Therefore, good mosquito protection particularly at night is important when traveling to areas where malaria is endemic. In areas with a high risk for getting infected it is recommended to take a prophylactic medication.

Chikungunya

Chikungunya is a viral disease that is most commonly spread by Aedes aegypti and Aedes albopictus, that is the same mosquitos that also spread the Zika and dengue virus.

The first symptoms of Chikungunya typically appear 4-8 days after the bite and include a sudden onset of fever that is frequently accompanied by severe joint pain. Treatment includes managing the fever and joint pain—there is no specific anti-viral treatment for Chikungunya. As of 2024 a Chikungunya vaccine is licensed in the European Union under the name Ixchiq, however not yet in Switzerland

Preventing Mosquito-Borne Diseases

All four above mentioned diseases have a key element in common: they are transmitted by mosquito bites. And the best way to prevent mosquito-borne diseases is of course by preventing mosquito bites. You can do this by

wearing mosquito repellent with a DEET content of 30-50%,
wearing long, light-colored clothing (which can additionally be treated with an insecticide) and
sleeping under an intact mosquito net with the air conditioning running.

In some cases, a prophylactic malaria medication and/or Dengue-Vaccination may be recommended.

A general rule for traveling safely is good preparation. This includes knowing what you need to be aware of while traveling. A travel consultant can help you to evaluate how to optimally prepare for your individual travel plans. Book a travel consultation to better understand what you may be at risk of while traveling, the vaccines that are recommended, and how you can ensure you stay healthy while traveling.