Probable locally acquired mosquito-transmitted malaria in Georgia, 1999

Area of Science:

• Epidemiology
• Infectious Diseases
• Medical Entomology

Background:

• Malaria is a mosquito-borne infectious disease caused by Plasmodium parasites.
• While historically endemic in parts of the US, malaria cases are now rare and typically associated with travel to endemic regions.
• Understanding non-travel related malaria transmission is crucial for public health surveillance.

Observation:

• A case of malaria was reported in Colquitt County, Georgia, in a patient with no travel history or identifiable risk factors (e.g., transfusion, transplantation, needle sharing).
• Epidemiological investigation ruled out other potential transmission routes and found no other cases in the county.
• The patient resided near housing occupied by seasonal migrant workers from malaria-endemic areas of Mexico and Central America.

Findings:

• Despite the absence of detected adult or larval Anopheles mosquitoes at the patient's residence, the area is known to harbor Anopheles quadrimaculatus, a competent malaria vector.
• The patient's home proximity to migrant workers from endemic regions suggests a potential source of infection.
• The most probable transmission route was determined to be a bite from an Anopheles mosquito.

Implications:

• This case highlights the possibility of autochthonous (locally acquired) malaria transmission in non-endemic areas under specific epidemiological conditions.
• It underscores the importance of considering mosquito-borne disease transmission even in the absence of typical risk factors.
• Enhanced surveillance and vector control measures may be necessary in areas with populations originating from malaria-endemic regions.