Causes and Risk Factors of Malaria
Usually, malaria gains access into your blood from the saliva of a female Anopheles mosquito after the insect feeds on someone else with the disease.
Parasites That Cause Malaria
P. falciparum This species is found in tropical and subtropical regions worldwide, but it’s especially common in Africa.
Falciparum malaria is the deadliest form of malaria because it multiplies rapidly, rupturing red blood cells. These damaged cells can clog small blood vessels, including in your brain.
P. vivax This species is found mostly in Asia, Latin America, and some parts of Africa.
P. vivax has a dormant stage in the liver. As a result, it can invade your blood up to two years after the infecting mosquito bite, making you sick again.
These delayed infections (relapses) can also reintroduce malaria to areas of the world where it was previously eliminated.
P. ovale This species is found mostly in Africa and the islands of the western Pacific. Like P. vivax, it can also remain dormant in your liver and cause relapses months or years later.
P. malariae This species is found worldwide. If untreated, it can cause a chronic lifelong infection or serious complications like nephrotic syndrome, a serious kidney disease.
P. knowlesi This species is found throughout Southeast Asia in macaque monkeys. It can also infect humans and progress rapidly to severe infection.
Malaria Risk Factors
There hasn’t been ongoing transmission of malaria in the United States since the early 1950s. The disease was effectively eliminated through a combination of water management, insecticides, and other treatment and prevention efforts.
But there are numerous cases each year of travelers leaving the United States, becoming infected, and returning to the country.
Occasionally, a small outbreak of malaria occurs in the United States, when local mosquitoes spread the disease from an infected traveler. So far, these episodes have been contained effectively, without malaria posing an ongoing threat.
Destination-related risk factors include:
Geographic region Areas of the world where malaria is endemic (circulates widely) tend to be tropical, subtropical, or at low elevations.
This is because warm temperatures are needed for the parasite to mature within mosquitoes.
The Centers for Disease Control and Prevention has a table of malaria information by country to see if your travel destination has endemic malaria.
In general, your risk is higher if you travel to sub-Saharan Africa than most areas of Asia or the Americas.
Type of accommodation Lodging that has window screens or air conditioning poses a lower malaria risk than open-air or tented accommodations.
You’re also at greater risk if your itinerary includes outdoor dining or entertainment, especially in the evening.
Season Hotter and wetter times of the year tend to be associated with greater malaria transmission.
One reason for this is that rainfall can create collections of water, encouraging the breeding of mosquitoes that transmit malaria.
Plan Announced to Eliminate Malaria Worldwide in a Generation
It’s possible that during cooler times of the year, you won’t need to take as many preventive measures if you travel to certain areas where malaria is endemic.
Risk factors related to the type of traveler include:
Pregnancy If possible, travel to an area with malaria transmission should be delayed until after giving birth. If delaying the trip isn’t possible, it’s essential to take a drug to help prevent malaria.
Malaria during pregnancy raises the risk of miscarriage, premature birth, and low birth weight, reducing the chances of the baby’s survival.
Visiting friends and relatives People who are originally from an endemic region but have moved, and then go back to visit, are the group at highest risk for malaria in the United States.
A lot of these people don’t know that they need to take medicine to prevent malaria. Some may believe they have immunity from growing up in a malaria-prone area, but any such immunity is only temporary and is quickly lost when someone moves away.
People who visit friends and relatives, as opposed to tourists or business travelers, are also likely to spend more time in the destination country and to stay in private residences rather than hotels.
