Method and Organism Discussions

Discussion #1C: Diagnosis, Treatment, and Prevention of Malaria in the U.S.

Abstract: JAMA. 2022;328(5):460-471. doi:10.1001/jama.2022.12366

https://jamanetwork.com/journals/jama/article-abstract/2794759

Malaria is caused by protozoa parasites of the genus Plasmodium and is diagnosed in approximately 2000 people in the US each year who have returned from visiting regions with endemic malaria (travelers, not endemic area residents). The mortality rate from malaria is approximately 0.3% in the US and 0.26% worldwide.

NOTE: The majority of these patients have not been exposed to malaria before (unlike patients who live in endemic areas). Consequently, they have no residual antibody (immunologically naïve), non-specific symptoms, and usually a very low parasitemia. They tend to present very early in the infection and do not display typical symptoms (periodic fevers) like those seen in patients who live in endemic areas.

Patients: 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 U.S. acquired the infection in Africa. Of the approximately 2000 people diagnosed with malaria in the U.S. in 2017, an estimated 82.4% were adults and about 78.6% were Black or African American. Among U.S. residents diagnosed with malaria, 71.7% had not taken malaria chemoprophylaxis during travel. In 2017 in the US, P falciparum was the species diagnosed in approximately 79% of patients, whereas P vivax was 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 falciparum has developed resistance to chloroquine in most regions of the world, including Africa. First-line therapy for P falciparum malaria in the U.S. is combination therapy that includes artemisinin. If P falciparum was 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, and P knowlesi are typically chloroquine sensitive, and treatment with either artemisinin-based combination therapy or chloroquine for regions with chloroquine-susceptible infections for uncomplicated malaria is recommended. Intravenous artesunate is the recommended first-line therapy for severe malaria. 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 vivax and P ovale require 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.