5 Alarming Vector-Borne Diseases Around the World

Twelve “death ships” docked in the port of Messina, Italy, in October 1347. Almost all crew members were discovered dead, and to the horror of dock visitors, the living were infected with an unknown disease that covered them in oozing black boils. The Black Death had arrived in Europe. 

The deadliest pandemic in human history, the black death claimed the lives of up to 25 million people, about 30% of the continent’s population. The cause was unknown at the time, but today, we know that this bubonic plague was caused by the bacterium Yersinia pestis, which was spread by infected fleas.  

Plague is not as remotely threatening as it was in medieval Europe; however, many other vector-borne diseases continue to plague humanity. In fact, diseases spread by fleas, ticks, mosquitoes and other infected insects are only becoming more prevalent. Here are five of the world’s most concerning vector-borne diseases.  

  1. West Nile Virus 
    West Nile virus (WNV) is spread via mosquito bites. The majority of people infected with WNV — around 80% — experience no symptoms. The remaining 20% develop West Nile fever, and less than 1% develop a more serious form of the disease, such as West Nile encephalitis, which can result in seizures, coma, paralysis and in rare cases, death.  

    Mosquitoes of the genus Culex are the most common carriers, particularly Cx. pipiens (the common house mosquito). Mosquitoes like Cx. pipiens contract the virus by feeding on infected birds, the natural hosts for WNV. They then pass on the virus to humans and animals during later blood meals. With their penchant for blood, mosquitoes are the most significant arthropod vectors for the disease — and we’ll be seeing more of them on this list. 

  2. Lyme Disease 
    Lyme disease is a spread by blacklegged ticks, or deer ticks, infected with the bacterium Borrelia burgdorferi. Lyme disease symptoms include fever, headache, fatigue, body aches and a telltale bull’s-eye-shaped rash. Most cases can be cured with a course of antibiotics; however, some people develop a condition called Post-Treatment Lyme Disease Syndrome (PTLDS), which is characterized by persistent symptoms of fatigue, pain and difficulty thinking.   

    Lyme disease is the most common vector-borne disease in the U.S. and Europe and is among the most common tick-borne infections around the world. As a result of climate change, blacklegged ticks are expanding to new territories and higher altitudes in Canada as well as Austria, Sweden, Germany, Norway and the Czech Republic, which could lead to a greater prevalence of tick-borne diseases.  

  3. Dengue 
    Another viral infection transmitted through the bite of infected mosquitoes, dengue virus infects an estimated 100-400 million people every year. Most infections — over 80% — are mild, but in rare cases, a person can develop severe dengue, a potentially fatal flu-like illness. A preventative vaccine is available, but there’s no treatment for dengue or severe dengue, which is what makes mosquito surveillance so important in affected regions.  

    The dengue virus is primarily transmitted by Aedes aegypti (the yellow fever mosquito) and, in some cases, by Ae. Albopictus (the Asian tiger mosquito). The Asian tiger mosquito has reached as far as the northeastern U.S., but climate change could lead to it — and the virus — pushing into Canada. While the Asian tiger mosquito is established in the southern fringes of Europe, including Italy, Southern France, and Southeastern Spain due to the global transportation of used tires and shipments of ornamental bamboo, the yellow fever mosquito is more prominent, and the continent is now under threat of an outbreak due to it. All told, half of the world’s population is at risk of contracting dengue.  

  4. Chikungunya  
    We can again thank the yellow fever and Asian tiger mosquitoes for spreading this virus. Chikungunya may not be as well known as the other entries on this list, but it’s a serious disease nonetheless. Symptoms include fever, headache, fatigue, rash, and joint and muscle pain. Most people make a full recovery, but in rare cases, joint pain can last for months, years even. Like dengue, there’s no specific treatment for chikungunya, leaving medical professionals to focus on relieving symptoms.  

    Chikungunya was first identified in 1952 in Tanzania, where it remained isolated until a 2004 outbreak in Kenya. Since then, the disease has spread to over 60 countries. Asia and North and South America are the regions most affected by chikungunya, but outbreaks have also been seen in Africa and Europe. As with other mosquito-borne diseases, reducing the number of breeding sites (locations with standing water) is key to preventing the spread of chikungunya. 
  5. Zika 
    Like dengue, the Zika virus is spread primarily by yellow fever mosquitoes. Symptoms are usually mild and include fever, conjunctivitis and malaise, but what makes Zika so frightening are complications that can arise during pregnancy. A pregnant woman who contracts the virus from an infected mosquito can pass on the virus to her fetus, potentially leading to serious birth defects. There’s no preventative vaccine or treatment for Zika infection.  

    Zika virus made headlines in 2015 and 2016 when large outbreaks occurred in North and South America, with local transmissions reported in Florida and Texas. Luckily, no cases have been confirmed in the U.S. since 2019. Nearly 90 countries and territories have reported cases of Zika infection, and a single mosquito feeding on an infected traveler is enough to spread the virus to new regions.  

The Growing Need for Entomologists Around the World 

Insects and other arthropods are expanding to new territories as a result of climate change. As cold regions continue to warm, vectors for disease will increasingly threaten human populations. Managing vector-borne diseases requires a coordinated effort among countries, and entomologists are at the forefront of their efforts to monitor and control fleas, ticks, mosquitoes and other disease-carrying insects. 

Study at UF’s World Renowned Entomology Department 

The University of Florida is home to the number-one ranked entomology program in the world. We offer a 30-credit, non-thesis master’s degree program and a 15-credit graduate certificate program, each of which can be tailored with a specialization option.  

International students, particularly those in Canada and Europe, will benefit from our online master’s degree or graduate certificate in medical entomology. Our medical entomology programs explore arthropod-related hazards, particularly mosquito-transmitted diseases, in preparation for careers in the public health sector. At the University of Florida, students around the world learn how to apply integrated pest management practices to protect people from mosquitoes, ticks and other disease-carrying insects and arthropods. 

Ready to protect the world from vector-borne diseases? Explore our programs, or apply now if you’re ready to join the number-one ranked entomology program in the world.  


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