Malaria
has been eradicated in certain areas where it was previously endemic.
Despite the interruption of transmission, these areas are often at risk
for the reintroduction of the parasite.
This
risk is unlikely to abate given migration and travel patterns as well
as the ongoing presence of competent mosquito vectors. Most malaria cases
that do occur in malaria-free areas are credited to persons returning
to the country from visiting or moving from endemic areas ("imported"
malaria).
However other mechanisms for cases to occur include "airport"
malaria, locally transmitted mosquito borne cases, congenital malaria,
and through blood transfusions and organ transplants.
Number of Malaria cases among U.S. and foreign civilians,
by year, 1973 to 2004.
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Imported
Malaria
In
the United States, about 1,200 malaria cases are reported annually which
are mostly attributed to imported malaria. These cases describe travelers
or immigrants coming from malaria endemic areas, where they were infected,
and developing signs of malaria after arriving in the United States.
Imported
malaria cases will continue to be a problem for the foreseeable future,
as the mobility of tourists and migrants is increasing.
Prompt
reporting of patients with malaria to public health authorities and adequate
assessment of risk factors for malaria in all cases allows initiation
of an appropriate public health response to prevent reestablishment of
malaria transmission.
Therefore,
continued domestic surveillance
and prompt diagnosis and treatment are crucial to prevent the reintroduction
of malaria into areas that are currently malaria-free.
Malaria
Surveillance United States 2004
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Locally
Transmitted 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 abundance of competent
vectors, especially in the southern states. At the request of the
states, CDC assists in these
investigations of locally transmitted mosquito borne malaria. The
most recent collaborative investigation identified an outbreak of malaria
in Palm
Beach County, Florida.
"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, they can bite local residents
who can thus acquire malaria without having traveled abroad
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. See Congenital
Malaria as a Result of Plasmodium malariae - North Carolina, 2000
Infected
Blood Products
Transfusion-transmitted
malaria (TTM) is rare in the United States, but it is a potential severe
complication in blood recipients. Only about one case of malaria occurs
for every 4 million units of blood collected.
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. See Transfusion-Transmitted
Malaria - Missouri and Pennsylvania, 1996-1998.
Page last modified : May 4, 2004
Content source: Division of Parasitic Diseases
National Center for Zoonotic, Vector-Borne, and Enteric Diseases (ZVED)
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