Malaria Surveillance - United States, 2016

Area of Science:

• * Vector-borne diseases surveillance
• * Parasitic infections epidemiology
• * Public health entomology

Background:

• * Malaria is transmitted by Anopheles mosquitoes, primarily affecting travelers to endemic regions.
• * While rare, domestic malaria acquisition can occur through blood products, congenital transmission, or local mosquito-borne spread.
• * Surveillance is crucial for understanding malaria occurrence, guiding prevention, and controlling local transmission.

Purpose of the Study:

• * To summarize confirmed malaria cases in the U.S. with symptom onset in 2016.
• * To analyze trends in malaria cases and identify contributing factors.
• * To assess the effectiveness of current prevention and treatment strategies.

Main Methods:

• * Data collected through the National Malaria Surveillance System (NMSS) and National Notifiable Diseases Surveillance System (NNDSS).
• * Inclusion of CDC reference laboratory reports and clinical consultations.
• * Analysis of case investigations, diagnostic assistance, and antimalarial drug resistance marker testing.

Main Results:

• * 2,078 confirmed malaria cases reported in 2016, a 36% increase from 2015, marking the highest total since 1972.
• * Most cases (1,729) originated from Africa, with 61.4% from West Africa; P. falciparum was the predominant species (68.2%).
• * Poor adherence to chemoprophylaxis (94.0%) was observed among U.S. residents; 14.7% of cases were severe, with seven deaths.

Conclusions:

• * The rise in malaria cases reflects increased global travel to endemic areas, with inadequate use of preventive measures by travelers.
• * Antimalarial drug resistance, particularly to pyrimethamine and sulfadoxine, is a significant concern.
• * Enhanced reporting completeness and adherence to chemoprophylaxis are vital for malaria control in the U.S.