Malaria Transmission in the United States

Mosquito-Borne Malaria

Outbreaks of locally transmitted cases of malaria in the United States have been small and relatively isolated, but the potential risk for the disease to re-emerge is present due to the presence of particular mosquitoes capable of passing malaria parasites from one human to another, especially in the southern states. At the request of the states, CDC assists in these investigations of locally transmitted mosquito-borne malaria.

“Airport” Malaria

“Airport” malaria refers to malaria caused by infected mosquitoes that are transported rapidly by aircraft from a malaria-endemic country to a non-endemic country. If the local conditions allow their survival upon arrival, they can potentially bite local residents who can thus acquire malaria without having traveled abroad. Airport transmitted malaria is challenging to confirm, but can be considered after exclusion of other likely explanations.

Congenital Malaria

In congenital malaria, infected mothers transmit parasites to their child during pregnancy before or during delivery. Therefore, though congenital transmission is rare, health-care providers should be alert to the diagnosis of malaria in ill neonates and young infants, particularly those with fever.

During evaluation, health-care providers should obtain a complete and accurate travel and residency history on the patient and close relatives. Patients should be asked about transfusion of blood products.

The absence of recent foreign travel or a long interval between immigration of the mother and the birth of the infant being examined should not discourage clinicians from obtaining blood films on the patient to rule out a potentially life-threatening but treatable infection.

Transfusion-Transmitted Malaria

Transfusion-transmitted malaria is rare in the United States, but it is a potential severe complication in blood recipients. On average, only one case of transfusion-transmitted malaria occurs in the United States every 2 years.

Because no approved tests are available in the United States to screen donated blood for malaria, prevention of transfusion-transmitted malaria requires careful questioning of prospective donors.

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