Beware of the Buzzing Biters!

Diseases transmitted to humans by mosquitoes, called mosquito-borne diseases, are serious health issues. They can make people very sick or even kill them. The World Health Organization says that diseases transmitted by mosquitoes and other insects make up 17% of all infectious diseases in the world. They cause 700,000 deaths each year [1]. Mosquitoes are the most common type of insect when it comes to spreading diseases. Some mosquito-borne diseases include chikungunya, Zika, yellow fever, West Nile, Japanese encephalitis, dengue, and malaria.

Mosquito-borne diseases can affect public health and the economy [1]. When people get sick, it puts pressure on local healthcare systems. Sick people often cannot go to work, so this causes industries to be less productive and local economies to lose money. Limited resources and poor healthcare can make outbreaks of mosquito-borne diseases especially harmful in some places, and vulnerable groups, such as children, pregnant women, and poor people are often among the worst affected. This can make inequalities worse and increase health disparities [1]. To reduce mosquito-borne diseases and protect people’s health, it is important to prevent mosquito bites and control mosquito populations.

How are Mosquito-Borne Diseases Transferred to Humans?

Mosquitoes are found worldwide, even in the Arctic [2], but they are especially common in warm, moist tropical and subtropical regions. There are about 3,500 mosquito species, with the most common being Anopheles, Aedes, and Culex. Anopheles transmits malaria and filariasis. Aedes transmits yellow fever, dengue, chikungunya, Zika, and yellow fever. Culex transmits West Nile, Japanese encephalitis, and filariasis [2]. But only a small number (3%) of mosquitoes spread diseases to people [1].

To get nutrients for their eggs, female mosquitoes feed on blood from humans and other animals (Figure 1). When they feed, they also inject saliva, which might contain disease-causing pathogens like viruses. In contrast, male mosquitoes mainly feed on nectar from plants. Some mosquitoes can be picky eaters, sticking to just a few species [2], but others are more flexible and will feed on mammals, birds, and reptiles. Mosquitoes that feed on humans and allow pathogens to multiply in their salivary glands can spread diseases to humans [2].

Mosquitoes lay eggs on water or other moist surfaces, including lakes, ponds, and swamps, and holes in trees (Figure 1). Humans also make trash that can hold water, like disposable bottles, cans, and old tires. More trash means more places for mosquitoes to breed [3]. People who do not have running water in their homes often store their water in open containers, which can also give mosquitoes a place to breed. Aedes mosquitoes, which are common in tropical areas, have spread this way [1]. These mosquitoes transmit a disease called dengue, which is spreading widely in the tropical world—even in areas where both Aedes mosquitoes and dengue were previously eliminated.

Humans can become infected with dengue when an infected female Aedes mosquito bites a person and sucks their blood. Mosquitoes get infected with dengue virus when they bite a person who has the virus. The virus reproduces in the mosquito for 8–12 days [2]. After that, the mosquito can transmit the virus to humans. Infected mosquitoes carry the virus, and can continue to infect people, for their entire lives—usually around 6 weeks [3].

How Do Mosquitoes Find Their Victims?

Mosquitoes find their victims by sensing chemicals the animals breathe out and their body heat. Some people get bitten by mosquitoes more often than others. Many things can make a person more attractive to mosquitoes [4]:

• People with type O blood get bitten by mosquitoes more often.

• Mosquitoes like warm bodies. People who exercise or live in hot climates are more prone to being bitten.

• Mosquitoes like sweat because of the chemicals in it. People who sweat a lot are more likely to be bitten.

• Pregnant women get more mosquito bites than non-pregnant women. Pregnant women make more carbon dioxide and body heat. Mosquitoes like that.

• Certain medications, such as the one used to treat malaria, can attract mosquitoes.

• People with medical conditions like diabetes and kidney disease are more prone to mosquito bites.

What Do Mosquito-Borne Diseases Feel Like?

Malaria, dengue fever, and Zika are three examples of mosquito-borne diseases. We will briefly describe their symptoms below.

Malaria

Malaria can cause fever, chills, sweating, and flu-like symptoms. If not treated, it can cause brain damage, breathing issues, organ failure, and death. Malaria is caused by a parasite spread by certain mosquitoes of the species Anopheles.

Dengue

Dengue is a virus that can cause high fever, severe headache, rash, pain behind the eyes, joint and muscle pain, nausea, and vomiting. In some cases, it can develop into a more severe form that can be life-threatening, called dengue hemorrhagic fever. Dengue viruses are spread by Aedes aegypti and Aedes albopictus mosquitoes.

Zika

Zika is a virus that can either cause no symptoms or mild symptoms like fever, rash, joint pain, and red eyes. Pregnant women who get infected may face greater risks because Zika virus can cause disabilities in their babies. Mosquitoes that spread Zika are of the species Aedes aegypti.

Preventing Mosquito-Borne Diseases

People can protect themselves from mosquito bites to help prevent the spread of mosquito-borne diseases. People can also take steps to stop mosquitos from laying eggs nearby. To avoid mosquito bites, use mosquito repellent, wear long sleeves and pants, and use screens on windows and doors to keep mosquitoes out. To prevent mosquitoes from laying eggs nearby, remove any standing water near homes, so that mosquitoes do not have as many places to lay eggs.

Climate change is causing certain areas to become hotter and wetter [1, 3]. This can help mosquitoes thrive and even help them move to new locations, putting more people at risk of mosquito-borne diseases. This means that fighting climate change is another important step for preventing these diseases.

Preventing mosquito-borne diseases is important for public health. To keep people healthy, countries where mosquito-borne diseases are a problem might need to develop mosquito-control programs and vaccination campaigns for mosquito-borne diseases for which vaccines exist. Educating the public is also critical, to promote behaviors that reduce the risk of mosquito bites. Finally, as we mentioned, measures to protect the environment from further climate change are also important. If both individuals and health officials take the necessary steps to prevent mosquito-borne diseases, they will help to create a healthier world.

Glossary

Mosquito-Borne Diseases: ↑ Illnesses that spread from one person or animal to another through the bite of an infected mosquito.

Health Disparities: ↑ Differences in health that depend on the conditions where people are born, grow, live, study, and age.

Pathogens: ↑ Microscopic living things like viruses, bacteria, or parasites that can invade our bodies and make us sick.

Vaccination Campaign: ↑ A large effort to give shots to many people at the same time to protect them from a specific disease.

Acknowledgments

The authors would like to express their gratitude to the International Development Research Center (IDRC) for their ongoing support of comprehensive initiatives in the Latin America and Caribbean region such as TRACE-LAC and COLEV.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.