Local transmission of Plasmodium vivax malaria—Palm Beach County, Florida, 2003

Morbidity and Mortality Weekly Report, Sept 26, 2003 by JM Malecki, S Kumar, BF Johnson, ML Gildey, TE O'Connor, J Petenbrink, L Bush, J Morand, MT Perez, S Pillai, L Crockett, C Blackmore, RA Wirtz, JW Barnwell, AJ DaSilva, LM Causer, ME Parise

The majority of malaria cases diagnosed in the United States are imported, usually by persons who travel to countries where malaria is endemic (1). However, small outbreaks of locally acquired mosquito-transmitted malaria continue to occur (2). Despite certification of malaria eradication in the United States in 1970 (3,4), 11 outbreaks involving 20 cases of probable locally acquired mosquito-transmitted malaria have been reported to CDC since 1992 (5-17), including two reported in July 1996 from Palm Beach County, Florida (Palm Beach County Health Department, unpublished data, 1998). This report describes the investigation of seven cases of locally acquired Plasmodium vivax malaria that occurred in Palm Beach County during July-August 2003. In addition to considering malaria in the differential diagnosis for febrile patients with a history of travel to malarious areas, healthcare providers also should consider malaria as a possible cause of fever among patients who have not traveled but are experiencing alternating fevers, rigors, and sweats with no obvious cause.

Case Reports

Case 1. On July 24, a man aged 37 years was admitted to hospital A with a 6-day history of fever, chills, headache, anorexia, and vomiting. On July 25, P. vivax was identified on a blood smear. The patient recovered after treatment with doxycycline, quinine, and primaquine. The patient is a plumber who reported working outside during the day but who stayed indoors at night.

Case 2. On July 22, a man aged 46 years reported to the emergency department (ED) of hospital A with a 3-day history of fever, headache, chills, anorexia, nausea, vomiting, dehydration, and malaise. He was treated with intravenous fluids and discharged with levofloxacin. On July 24, he returned to the ED with worsening symptoms and was admitted with a diagnosis of pneumonia. On July 25, P. vivax was identified on a blood smear. The patient recovered after treatment with doxycycline, quinine, and primaquine. The patient is a construction worker who reported working outside.

Case 3. On August 15, a man aged 32 years was admitted to hospital A with a 33-day history of fever, chills, headache, vomiting, and intermittent sweating. He had consulted several physicians for his symptoms and had been treated unsuccessfully with azithromycin and prednisone. On the day of admission, P. vivax was identified on a blood smear. The patient recovered after treatment with doxycycline, quinine, and primaquine. He reported having played golf and tennis in the evenings.

Case 4. On August 19, a man aged 45 years visited the ED of hospital A with a 2-day history of fever, chills, anorexia, arthralgias, and diarrhea and was discharged on ibuprofen. The patient visited the ED again on August 21 for these same symptoms, was evaluated, and discharged. On August 22, he returned to the ED with worsening symptoms and mental confusion and was admitted; a blood smear demonstrated the presence of P. vivax. He recovered after treatment with chloroquine and primaquine. The patient slept in a homeless camp in a wooded area near a canal. He reported using insert repellent.

Case 5. On August 24, a man aged 23 years was admitted to hospital A with a 12-day history of fever, chills, arthralgias, diarrhea, and vomiting. On the day of admission, P. vivax was identified on a blood smear. He had visited the FD several days previously with the same complaints and had been treated with antibiotics for a respiratory infection. The patient recovered after treatment with chloroquine and primaquine. He reported fishing at a community pond in the evenings.

Case 6. On August 25, a person aged 17 years was admitted to hospital B with an 8-day history of fever, chills, and headaches. On August 26, P. vivax was identified on a blood smear. He recovered after treatment with doxycyline, quinine, and primaquine. The patient is a student and reported spending rime at a pond near his house.

Case 7. On August 26, a man aged 48 years was admitted to hospital C with a 7-day history of fever and chills. He had self-treated earlier that week with antibiotics. P. vivax was identified on a peripheral blood smear on the day of admission. He recovered after treatment with chloroquine and primaquine. The patient is a carpenter and works until 8 p.m. in an open warehouse.

Epidemiologic Investigation

All seven patients reported having no previous history of malaria, recent blood transfusion, organ transplantation, or intravenous drug use. Six of the seven patients reported never having traveled to regions where malaria is endemic. Patient 7 emigrated to the United States from Bogota, Colombia, in July 2001; although Bogota is free of malaria transmission, malaria is endemic in some areas of Colombia.

All seven patients live within the West Palm Beach area (Figure) within 10 miles of Palm Beach International Airport. No international seaport exists nearby. Patients 1 and 2 attended the same local party on July 4. None of the other patients had any known common activities or interactions.