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World Health Day – Vector-Borne Diseases

 Photo: Worker fogging villageApril 7, 2014 marks World Health Day and the 66th anniversary of the World Health Organization (WHO). This year’s theme is vector-borne diseases.

Over half the world's population is at risk from vector-borne diseases such as malaria and dengue. Vectors like mosquitoes, ticks, and fleas transmit parasites, viruses, or bacteria between people or between animals and people. Each World Health Day, the World Health Organization (WHO) selects a theme that highlights a global public health issue. This year's theme is vector-borne diseases, with a first-time focus on dengue.

Vector-borne diseases account for 17% of the estimated global burden of all infectious diseases. Global trade, rapid international travel, and environmental changes such as climate change and urbanization are causing vectors and vector-borne diseases to spread beyond borders. Many neglected tropical diseases, including dengue, Chagas disease, leishmaniasis, lymphatic filariasis, and onchocerciasis are vector-borne; other vector-borne diseases include typhus and spotted fevers.

Forty percent of the world's population is at risk from dengue virus; there are an estimated 390 million dengue infections each year in over 100 countries. Dengue is the world's fastest growing vector-borne disease, with a 30-fold increase in disease incidence over the last 50 years. Southeast Asia and Latin America are especially affected but dengue also occurs in Africa, where cases are less-often diagnosed.

Malaria is a vector-borne disease that is one of the most severe public health problems worldwide. It is a leading cause of death and disease in many developing countries, where young children and pregnant women are the groups most affected. The WHO estimates that in 2012, there were 207 million cases of malaria and 627,000 people died of malaria. Most deaths were among children in Africa.

What is CDC doing about vector-borne diseases?

A local health worker in Havana, Cuba, uses a flashlight to check for signs of water and mosquito eggs inside tires. Automobile tires are ideal breeding sites for some types of mosquitoes, which lay their eggs in water inside the tire. Photo credit: WHO/A. Crump

A local health worker in Havana, Cuba, uses a flashlight to check for signs of water and mosquito eggs inside tires. Automobile tires are ideal breeding sites for some types of mosquitoes, which lay their eggs in water inside the tire. Photo credit: WHO/A. Crump

  • The U.S. President's Malaria Initiative (PMI), led by USAID and implemented together with CDC, is working in 19 focus countries in Africa. In 2012 alone, PMI procured more than 21 million long-lasting insecticide-treated nets, protected more than 30 million residents by spraying their houses with residual insecticides, and procured more than 72 million doses of treatment. Malaria's toll would be much higher without the efforts of CDC and other global partners. From 2000 through 2012, the massive scale-up of malaria prevention and treatment interventions saved approximately 3.3 million lives globally, and malaria death rates in Africa were cut nearly in half.
  • To help with the 2020 goal of eliminating lymphatic filariasis globally, CDC is working in countries such as Togo that have completed the recommended elimination steps. This work is focused on developing ways to ensure that if there are any additional cases, they would be quickly detected and measures taken to prevent resurgent transmission.
  • CDC is working on a research test for onchocerciasis, a parasitic disease that causes blindness. The OV16 test is used on blood specimens to test for early infection. This will help onchocerciasis programs plan the final stages of elimination of this blinding disease.
  • A CDC-developed dengue vaccine, DENVax, is currently undergoing Phase 2 clinical trials in Singapore, Colombia, Thailand, and Puerto Rico. Preparations are underway for Phase 2b/Phase 3 trials to begin in late 2014.
  • CDC's Dengue Branch, located in Puerto Rico, is the largest research unit in the world dedicated to developing and testing improved methods for dengue prevention, diagnosis, control, and treatment. The Branch is working with the Puerto Rico Department of Health to develop a dengue elimination strategy when a vaccine is available.
  • CDC has developed and is testing new pesticides with a unique mode of action from currently available pesticides. These could be valuable additions to the arsenal of methods to control mosquitoes and ticks.

Though vector-borne diseases have the biggest impact on the world's poorest people, everyone, rich and poor, is at risk for infections. There are several major vector-borne disease threats in the U.S. including Lyme disease, West Nile virus, Rocky Mountain spotted fever, and babesiosis. Dengue is present in Puerto Rico and other U.S. territories. The best way people can prevent these infections is by preventing tick or mosquito bites using repellents, wearing long sleeves and pants, and showering after going outside to wash unattached ticks off your skin.

Read more about the people affected by vector-borne diseases and what CDC is doing to help:

Additional information about World Health Day is available at the WHO website. Learn more about vector-borne diseases and what CDC is doing about these emerging threats.