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Malaria in the United States | Malaria
Worldwide | Biology, Pathology, Epidemiology | Prevention
and Treatment
Malaria
in the United States
- 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. freeborni 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 (pneumonias),
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 symptomless 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.
Prevention
and Treatment
- Four Nobel
prizes have been awarded for work associated with malaria, to Sir Ronald
Ross (1902), Charles Louis Alphonse Laveran (1907), Julius Wagner-Jauregg
(1927) and Paul Hermann Muller (1948).
- Two important
currently used antimalarial drugs are derived from plants whose medicinal
values had been noted for centuries: artemisinin from the Qinghao
plant (Artemisia annua L, China, 4th century) and quinine
from the cinchona tree (South America, 17th century).
- Insecticide-treated bed nets decreased the mortality of children
aged 1-11 months in a trial in western Kenya in 1997-1999.
- A survey
in Southeast Asia in 1999-2000 showed that of 104 shop-bought samples
purportedly containing the antimalarial drug artesunate, 38% contained
no artesunate.
- The average cost for potentially life-saving treatments of malaria are
estimated to be US$0.13 for chloroquine, US$0.14 for sulfadoxine-pyrimethamine,
and US$2.68 for a 7-day course of quinine.
Page last modified : April 11, 2007
Content source: Division of Parasitic Diseases
National Center for Zoonotic, Vector-Borne, and Enteric Diseases (ZVED)
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