The United States eliminated malaria transmission in the early 1950s. It
did not eliminate the mosquitoes.
**During 2023, 10 cases of locally acquired — autochthonous —
mosquito-transmitted malaria were reported to the CDC from four US states,
after a twenty-year period with no such cases.**
Locally acquired means the person did not travel. The parasite came from a
mosquito that bit them in the United States, which requires an infected person
here, a competent mosquito here, and the right conditions — all three of which
still exist.
Why this report exists
Investigations of suspected autochthonous malaria **often raise public concern
and can require substantial public health resources**. They are also
genuinely complicated: a proper investigation has **epidemiologic, entomologic
and laboratory components**, and frequently requires coordination across
local, state and federal jurisdictions.
This guidance updates the CDC's 2006 version, and is based on subject
matter expertise, the outbreak response experience from 2023, and a
targeted literature review. It is written for local, state, tribal,
territorial and federal public health responders.
What it provides
An outline of the essential actions for such an investigation: the
components of the investigation, plus resources and tools for public health
personnel at every level.
Three strands run in parallel, and skipping any one leaves the question open:
| Strand | What it establishes |
|---|---|
| Epidemiologic | Who the case is, where they were, and whether anyone else was exposed |
| Entomologic | Which mosquitoes are present, and whether any carry the parasite |
| Laboratory | Which species and strain — and therefore whether cases are linked |
Without the entomology you cannot say transmission is local; without the
laboratory work you cannot link cases to each other or to an imported source.
Why it matters beyond ten cases
Ten cases in a country of 340 million is not an epidemic. The significance is
what it demonstrates: **the country remains susceptible to malaria
reintroduction**. Elimination is a state that has to be maintained, and the
twenty-year gap before 2023 measured luck and vector control as much as
immunity.
*Source: Ranadive N, Barratt JLN, Dotson EM, et al. CDC Operational Guidance
for Investigating Locally Acquired Mosquito-Transmitted Malaria — United
States, 2026. MMWR Recommendations and Reports, Centers for Disease Control
and Prevention.*
许可协议： CC0 1.0（公有领域） · 改编自 www.cdc.gov
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