World Mosquito Day 2021: Bringing Attention to the World’s Deadliest Animal


A female Anopheles gambiae mosquito takes a blood meal from a human host. This species, among others, is a known vector for malaria. Credit: CDC-PHIL

The meager, long-legged insect that annoys, bites, and leaves you with an itchy welt is not just a nuisance―it’s the world’s most deadly animalmedia icon.

  • In 2019, 409,000 people died from malaria and millions more become ill each year, including about 2,000 returning travelers in the United States. Nearly half of the world’s population is at risk of this preventable disease.
  • Lymphatic filariasis (LF), a parasitic disease transmitted through repeated mosquito bites over a period of months, affects more than 120 million people in 72 countries and is a leading cause of permanent disability worldwide.
  • In 2018, the number of severe cases of West Nile virus was nearly 25% higher in the continental United States than the average from 2008 to 2017.
  • In the past 30 years, the worldwide incidence of dengue has risen 30-fold. Forty percent of the world’s population, about 3 billion people, live in areas with a risk of dengue. Dengue is often a leading cause of illness in areas of risk.

You can protect yourself from these diseases by avoiding bites from infected mosquitoes.

CDC is committed to providing scientific leadership in fighting these diseases, at home and around the world.

From its origins, CDC has played a critical role in eliminating malaria from the United States
Office of Malaria Control in War Areas (MCWA)

In 1945, Office of Malaria Control in War Areas (MCWA) personnel gathered for a meeting to analyze data received during investigations in the field. These data were used to formulate an epidemiologic plan of action in order to solve an unidentified epidemiologic outbreak and ultimately eliminate malaria from the United States. Credit: CDC-PHIL

CDC’s mission to combat malaria began at its inception on July 1, 1946, when much of the early work done by CDC was concentrated on the control and elimination of malaria in the United States. With the successful reduction of malaria in the United States, the CDC switched its malaria focus from elimination efforts to prevention, surveillance, and technical support both domestically and internationally. This is still the focus of CDC’s malaria work today.

Since 2001, global health action has cut the number of malaria deaths in half―saving almost 8 million lives. CDC co-implements the U.S. President’s Malaria Initiative,external icon led by the U.S. Agency for International Development, in 24 countries in sub-Saharan Africa and 3 in the Greater Mekong Subregion.

Today, CDC works to eliminate the global burden of malaria and other mosquito-borne diseases by conducting research into new tools and approaches to better prevent, detect, and control mosquito-borne diseases.

New threats from growing insecticide resistanceexternal icon and emerging urban mosquito vectors like Anopheles stephensi require innovative approaches to fighting this deadly foe.


Spatial repellants offer hope as a new tool to fight back against disease-spreading mosquitoes

While the global malaria burden has declined substantially as a result of the scale up of insecticide-treated bed nets (ITNs) and other interventions, malaria remains a major public health problemexternal icon, particularly in sub-Saharan Africa. CDC is working with the University of Notre Dame, the Kenya Medical Research Institute, and other partners in the Advancing Evidence for the Global Implementation of Spatial Repellents (AEGIS) consortium,external icon a 5-year Unitaidexternal icon*-funded effort to determine the efficacy of a novel spatial repellent product in preventing mosquito-borne diseases such as malaria, dengue, and chikungunya.

Spatial repellents work by releasing chemicals into the air where they elicit a range of behaviors in mosquitoes, such as movement away from the chemical stimulus, interfering with the mosquito’s ability to detect a human to feed on. The program includes clinical trials in three different countries: Kenya (where CDC is engaged), Mali, and Sri Lanka. Each trial will evaluate the efficacy and cost-effectiveness of a spatial repellent in reducing transmission and protecting against new infections of malaria (Kenya and Mali) and dengue (Sri Lanka). The AEGIS consortium will also conduct case studies among displaced populations in other geographic areas.

The ongoing COVID-19 pandemic required researchers to spend 12 months incorporating necessary protections, including procuring personal protective equipment for the study team in Kenya and developing standard operating procedures to minimize the risk of COVID-19 while interacting with study participants. The first step of the Kenya trial, four months of baseline work, is now complete. Throughout this phase, the study team recruited participants and established the baseline of malaria infection in participants. Implementation of the spatial repellent intervention is set to begin at the beginning of September 2021.

CDC helped to ensure the study team was provided the best technical guidance for safety while simultaneously administering research program protocols.

Malaria is not the only parasitic disease spread by mosquitoes: How CDC fights lymphatic filariasis

Lymphatic filariasis (LF), one of the world’s most stigmatizing and debilitating diseases, is also spread by the bite of an infected mosquito. More than 120 million people have LF worldwide, and another 1.3 billion live in areas where they are at risk of acquiring the infection.

Like malaria, LF is preventable with timely and targeted interventions. Some countries in Africa have observed an association between scale up of ITNs for malaria control and a decline in LF cases. This supports the strategy of integrated mosquito control in certain areas: what we do to combat one mosquito-borne disease can help in the fight against others.

CDC plays an important role in the global fight against LF by sharing strategic guidance on mosquito control and other ways to reduce infection risk, such as mass drug administration campaigns. These campaigns provide preventive medication annually to at-risk populations. Currently, CDC and its partners are engaged in efforts to eliminate LF from Haiti and American Samoa, as remaining areas in the Americas with ongoing transmission.

Learn more about how CDC and partners are working to eliminate LF and other neglected tropical diseases (NTDs):

*Unitaid is a global health agency engaged in finding innovative solutions to prevent, diagnose, and treat diseases such as HIV/AIDS, malaria, and tuberculosis more quickly, cheaply, and effectively, in low- and middle-income countries. Unitaid is now applying its expertise to address challenges in advancing new therapies and diagnostics for the COVID-19 pandemic, serving as a key member of the Access to COVID-19 Tools (ACT) Acceleratorexternal icon. Unitaid is hosted by the World Health Organizationexternal icon.

Additional Resources

World Mosquito Day 2021: CDC’s Efforts to Control the World’s Deadliest Animal—Photo Essay

Mosquitoes: CDC Center for Global Health Social Media Cards

Mosquitoes: CDC Center for Global Health Video

CDC Center for Global Health Director’s PMI 15th Anniversary Video

CDC: Mosquitoes

Page last reviewed: August 20, 2021