INFECTIONS - Medicine for Mountaineering and Other Wilderness Activities - page 317

Ebola Zaire Bats and direct contact

Ebola Reston Bats and direct contact

Ebola Tai Bats and direct contact

Ebola Bundibugyo Bats and direct contact

Arenaviruses

Lassa Fever Rodent contact

Junin Fever (Argentine Hemorrhagic Fever) Rodent contact

Machupo Fever (Bolivian Hemorrhagic
Fever)

Rodent contact

Guanarito Fever (Venezuelan Hemorrhagic
Fever)

Rodent contact

Sabia Fever (Brazilian Hemorrhagic Fever)

Whitewater Fever (United States)

Becausemostoftheseinfectionshaveageographicallylimiteddistribution,theyareun-
likely to strike mountaineers and adventure travelers who avoid centers of infection. Pre-
cautions against mosquito and tick bites further reduce the risk.
More information is available at www.cdc.gov/ncidod/diseases/virlfvr/virlfvr.htm .

PARASITIC DISORDERS
Malaria
Malaria is caused by protozoa of the genus Plasmodium and is transmitted by the bite
of infected mosquitoes. Worldwide, 300 to 500 million clinical infections occur each year,
more than tuberculosis, AIDS, measles, and leprosy combined. One million persons die
from malaria every year, 90 percent of whom are children less than six years old.
Malarial parasites are ingested along with the blood of an infected person or animal
when female Anopheles mosquitoes bite. The parasites undergo fertilization, reproduce in
themosquito'sgut,andaretransmittedtohumanswhenthemosquitoinjectssalivaintothe
skin during a subsequent bite. In the human, parasites invade red blood cells, multiply, and
releasedaughterparasites,destroyingredbloodcellsintheprocess.Thedaughterparasites
invade other red blood cells, and the process is repeated. The periodic release of parasites
produces recurrent episodes of fever; the destruction of red blood cells can eventually res-
ult in anemia.
The initial symptoms of malaria are muscular soreness and a low fever, which appear
aboutsixtotendaysafterabitebyaninfectedmosquito.Fourtoeightdayslater,thetypic-