According to the Centers for Disease Control and Prevention, mosquitoes are responsible for more than 700,000 human deaths globally each year, making them the world’s deadliest animal.
Malaria Global Toll and US Resurgence
Malaria remains the deadliest disease spread by mosquitoes, causing more than 600,000 deaths annually, with young children in sub-Saharan Africa bearing the brunt of the burden, according to available data. In 2023, the CDC and partners documented nearly 263 million cases and 597,000 deaths across 83 countries. While the United States eliminated malaria as a major public health problem in the early 1950s and typically records about 2,000 travel-linked cases in a standard year, the country experienced an unexpected local resurgence in 2023. According to public health authorities, ten locally acquired malaria cases were documented across Florida, Texas, Maryland, and Arkansas, marking the first time in 20 years that the United States experienced cases of locally acquired mosquito-transmitted malaria.
Dengue and West Nile Virus Surges Domestically
Mosquitoes also drive widespread transmission of dengue fever, a viral illness infecting an estimated 400 million people globally each year, resulting in roughly 100 million symptomatic cases and about 21,000 deaths, according to health reports. The problem is expanding inside U.S. borders; a CDC report published earlier this year revealed that domestic dengue cases in 2024 were 359% higher than the annual average from 2010 to 2023. Concurrently, domestic cases of West Nile virus reached a 22-year high. While the CDC typically records about 10 human West Nile cases through the end of June, this year’s count climbed to at least 48 cases, nearly 40 of which involved severe neuroinvasive infections. West Nile virus claims more than 130 lives annually in the U.S.
Global Threats: Yellow Fever and Japanese Encephalitis
Several other high-consequence mosquito-borne diseases continue to circulate internationally. Yellow fever, found in parts of Africa and South America, causes up to 82,000 deaths each year according to World Health Organization estimates, prompting health agencies to recommend vaccination for travelers heading to high-risk areas. Japanese encephalitis serves as the leading cause of viral encephalitis across much of Asia, generating an estimated 100,000 clinical cases annually. When symptomatic Japanese encephalitis progresses to brain inflammation, the fatality rate can reach 30%, and up to 50% of survivors face permanent neurological, cognitive, or behavioral deficits. Safe and effective vaccines exist for both yellow fever and Japanese encephalitis.
Frequently Asked Questions
What is the world’s deadliest animal?
According to the CDC, the mosquito is the world’s deadliest animal, accounting for more than 700,000 human deaths globally each year through the transmission of diseases like malaria and dengue.
How many mosquito species transmit diseases?
Out of more than 3,700 mosquito species identified globally, only a small fraction are known to transmit pathogens that pose a danger to humans.
What caused the recent malaria cases in the U.S.?
In 2023, the U.S. recorded 10 locally acquired malaria cases across Florida, Texas, Maryland, and Arkansas—experiencing cases of locally acquired mosquito-transmitted malaria for the first time in 20 years—prompting coordinated public health responses from state and local partners alongside the CDC.
Pro Tip for Mosquito Safety
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