Diagnosis, Treatment, and Prevention of Malaria in the US

Importance

Malaria is caused by protozoa parasites of the genusPlasmodiumand is diagnosed in approximately 2000 people in the US each year who have returned from visiting regions with endemic malaria. The mortality rate from malaria is approximately 0.3% in the US and 0.26% worldwide.

Observations

In the US, most malaria is diagnosed in people who traveled to an endemic region. More than 80% of people diagnosed with malaria in the US acquired the infection in Africa. Of the approximately 2000 people diagnosed with malaria in the US in 2017, an estimated 82.4% were adults and about 78.6% were Black or African American. Among US residents diagnosed with malaria, 71.7% had not taken malaria chemoprophylaxis during travel. In 2017 in the US,P falciparumwas the species diagnosed in approximately 79% of patients, whereasP vivaxwas diagnosed in an estimated 11.2% of patients. In 2017 in the US, severe malaria, defined as vital organ involvement including shock, pulmonary edema, significant bleeding, seizures, impaired consciousness, and laboratory abnormalities such as kidney impairment, acidosis, anemia, or high parasitemia, occurred in approximately 14% of patients, and an estimated 0.3% of those receiving a diagnosis of malaria in the US died.P falciparumhas developed resistance to chloroquine in most regions of the world, including Africa. First-line therapy forP falciparummalaria in the US is combination therapy that includes artemisinin. IfP falciparumwas acquired in a known chloroquine-sensitive region such as Haiti, chloroquine remains an alternative option. When artemisinin-based combination therapies are not available, atovaquone-proguanil or quinine plus clindamycin is used for chloroquine-resistant malaria.P vivax, P ovale, P malariae,andP knowlesiare typically chloroquine sensitive, and treatment with either artemisinin-based combination therapy or chloroquine for regions with chloroquine-susceptible infections for uncomplicated malaria is recommended. For severe malaria, intravenous artesunate is first-line therapy. Treatment of mild malaria due to a chloroquine-resistant parasite consists of a combination therapy that includes artemisinin or chloroquine for chloroquine-sensitive malaria.P vivaxandP ovalerequire additional therapy with an 8-aminoquinoline to eradicate the liver stage. Several options exist for chemoprophylaxis and selection should be based on patient characteristics and preferences.

Conclusions and Relevance

Approximately 2000 cases of malaria are diagnosed each year in the US, most commonly in travelers returning from visiting endemic areas. Prevention and treatment of malaria depend on the species and the drug sensitivity of parasites from the region of acquisition. Intravenous artesunate is first-line therapy for severe malaria.