MALARIA
FROM THE CDC
Malaria in the United States www.cdc.gov/malaria/.
* 1,337 cases of malaria, including 8 deaths, were reported for 2002 in the United States, even
though malaria has been eradicated in this country since the early 1950's
* Of the 1,337 malaria cases reported for 2002 in the United States, all but five were imported, i.
e., acquired in malaria-endemic countries.
* Between 1957 and 2003, in the United States, 63 outbreaks of locally transmitted mosquito-
borne malaria have occurred; in such outbreaks, local mosquitoes become infected by biting
persons carrying malaria parasites (acquired in endemic areas) and then transmit malaria to
local residents.
* Of the ten species of Anopheles mosquitoes found in the United States, the two species that
were responsible for malaria transmission prior to eradication (Anopheles quadrimaculatus in the
east and An. Freeborn in the west) are still widely prevalent; thus there is a constant risk that
malaria could be reintroduced in the United States.
* During 1963-1999, 93 cases of transfusion-transmitted malaria were reported in the United
States; approximately two thirds of these cases could have been prevented if the implicated
donors had been deferred according to established guidelines.
Malaria Worldwide
* Forty-one percent of the world's population live in areas where malaria is transmitted (e.g.,
parts of Africa, Asia, the Middle East, Central and South America, Hispaniola, and Oceania).
* Each year 350–500 million cases of malaria occur worldwide, and over one million people die,
most of them young children in sub-Saharan Africa.
* In areas of Africa with high malaria transmission, an estimated 990,000 people died of malaria
in 1995 – over 2700 deaths per day, or 2 deaths per minute.
* In 2002, malaria was the fourth cause of death in children in developing countries, after
perinatal conditions (conditions occurring around the time of birth), lower respiratory infections
(pneumonia's), and diarrheal diseases. Malaria caused 10.7% of all children's deaths in
developing countries.
* In Malawi in 2001, malaria accounted for 22% of all hospital admissions, 26% of all outpatient
visits, and 28% of all hospital deaths. Not all people go to hospitals when sick or having a baby,
and many die at home. Thus the true numbers of death and disease caused by malaria are likely
much higher.
Biology, Pathology, Epidemiology
* Residents of Asembo Bay (Western Kenya) were bitten 60-300 times a year by a malaria-
carrying mosquito in the 1990's, before control measures (including the use of insecticide-
treated bed nets) were put in place.
* Among the four malaria species that infect humans, Plasmodium vivax and P. ovale can
develop dormant liver stages that can reactivate after symptom less intervals of up to 2 (P. vivax)
to 4 years (P. Ovale).
* 84% of the blood transfusions given in March-June 2000 in a major hospital in Kinshasa
(Democratic Republic of Congo) were for anemia caused by malaria.
* Pregnant women have increased susceptibility to Plasmodium falciparum malaria; in malaria-
endemic countries, P. Falciparum contributes to 8-14% of low birth weight, which in turn
decreases the chance of a baby’s survival
* After a single sporozoite (the parasite form inoculated by the female mosquito) of Plasmodium
falciparum invades a liver cell, the parasite grows in 6 days and produces 30,000-40,000
daughter cells (merozoites) which are released into the blood when the liver cell ruptures. In the
blood, after a single merozoite invades a red blood cell, the parasite grows in 48 hours and
produces 8-24 daughter cells, which are released into the blood when the red blood cell
ruptures.
The Clinic