While no longer native to the United States, hospitalization from malaria occurs in this country more than most would believe. Why is that, and what can you do to protect yourself when you travel abroad to regions where malaria is active?
Today, we associate malaria with tropical or subtropical regions, but the parasite that causes malaria was once a big problem in the US. Malaria is caused by members of the family Plasmodium. The most virulent member of that group is P. faciparum, whose picture you can see above. The parasite is largely responsible for the illness and death that occurs from malaria.
A recent study published in the American Journal of Tropical Medicine and Hygiene took a close look at malaria in the US. Although the parasites are no longer native to this country, it is the leading cause of travel-associated illness.
From the most recent statistics, the Centers for Disease Control and Prevention (CDC) estimate that more than 200 million cases of malaria occurred around the world in 2015, with approximately 429,000 deaths, many of them children.
Spread by the bite of the Anopheles mosquito, malaria parasites target the liver upon entry into the human body. From there, they multiply and infect red blood cells, rapidly creating successive generations of parasites. Mosquitoes are unaffected by the parasites, but transfer the disease from infected to uninfected humans.
Because malaria is caused by a family of parasites, symptoms of the disease can vary, from mild to severe. There are two forms of the disease — uncomplicated and complicated — with diagnosis drawn from identification of the parasite and symptoms.
Symptoms of uncomplicated malaria include fever and chills, sometimes appearing and disappearing at intervals, sweating, body aches including headache, and nausea and vomiting.
In the US, malaria may be mistaken as influenza or a nasty cold by physicians who are not familiar with the disease. Severe malaria is a medical emergency that may cause anemia, seizures, coma, organ failure, and other life-threatening symptoms. Delayed treatment can mean death. Some malarial infections can cause relapse months or even years after initial infection.
According to this study, more than 22,000 people were treated in hospitals across the country for malaria between 2000 and 2014. Of those, 4,823 suffered complications like liver failure, respiratory difficulty, or coma, and 182 of these patients died. In a country where malaria is officially "eliminated," the study, conducted by researchers from the University of California, Los Angeles (UCLA), as well as the CDC, finds the number of cases of malaria in the US is steadily increasing. How? By import.
Travel-related diseases are gaining greater significance in an increasingly restless international world. Possibly the strongest example of travel-associated illness were the few cases of Ebola that entered the US through travelers. At present, the US could experience a measles outbreak from American visitors or foreign travelers moving through regions in Europe where measles outbreaks are underway.
Looking at travel-related cases of malaria between 2000 and 2014, the study made interesting findings including:
- Males represented a larger number of hospitalized malaria victims.
- Average patient age was 37, with increasing numbers after age 25 and decreasing cases after age 44.
- The species P. falciparum accounted for a majority of malaria infections, and most admissions occurred through the emergency department.
- The majority of patients lived in zip codes that correspond with average household incomes above the national average.
The study suggests the rise in malaria cases in the US is, at least in part, caused by American travelers who do not take adequate precautions prior to traveling to areas where malaria is active or endemic. Lead author Diana Khuu, a scientist at UCLA and epidemiology analyst at the Los Angeles County Department of Public Health, noted in a press release:
It appears more and more Americans are traveling to areas where malaria is common and many of them are not taking preventive measures, such as using anti-malarial preventive medications and mosquito repellents, even though they are very effective at preventing infections.
Malaria was once a serious problem in the US. During World War II, the government established the Malaria Control in War Areas (MCWA) agency to support state and federal efforts to prevent, control, eradicate, and survey malaria, and other diseases like typhus.
The mandate of the agency was later broadened and its name changed to the Communicable Disease Center (CDC) in 1946. By 1951, malaria was officially counted as eliminated in the US. The Communicable Disease Center was eventually renamed the Centers for Disease Control and Prevention. The CDC is located in Atlanta, Georgia because it was once the epicenter of malarial activity in the US.
The geographic spread of the Anopheles mosquito is worldwide (except Antarctica), and throughout the US. The CDC reports 63 outbreaks of locally-transmitted malaria occurred in the US between 1957 and 2015. Outbreaks occur when local mosquitoes bite infected persons who traveled from an area with active malaria, then feed on uninfected humans, spreading the disease.
If you are planning a trip abroad take steps to protect yourself from this serious infection. The CDC suggests taking actions that include:
- Check your destination: Is malaria active or endemic in the area you intend to travel? The CDC notes travelers to sub-Saharan Africa are at greatest risk for infection and death. Conduct a risk assessment based on your destinations and personal factors.
- Know about prevention: Investigate types of preventative drugs, their side effects, and speak with your doctor about the best choice for you. Get informed about malaria, how and where it is transmitted, and other measures you can take including treated mosquito netting, repellents, and malaria treatment drugs you can carry with you in case of infection.
- Be active on prevention: When you are traveling, follow recommended precautions, use repellent and protective measures, and take your preventative drug regimen on a daily basis. Some travelers quit after a few days and acquire a life-threatening disease when they had the means to prevent it in their luggage.
Every year, between 1,500 and 2,000 Americans bring home malaria along with memories of their travel abroad. Know your risk, and be sure you are protected against malaria.