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In the summer of 2009 locally transmitted Dengue returned to Florida after more than a 70 year absence (see Dengue Resurfaces In Key West).
Surprisingly it wasn't first detected by a doctor in Florida, but by an astute infectious disease specialist in Rochester, New York who was consulted by the GP a woman who had recently returned from the Sunshine State with persistent and unusual symptoms.
While local transmission of Dengue hadn't been reported since the 1940s, every year Florida's Arbovirus surveillance system detects hundreds of infected travelers from regions where dengue, malaria, Zika, and CHKV) are endemic.
Similarly, Malaria hadn't been reported in Florida in more than 40 years, until the early 1990s;
- In June 1990, a woman with no history of foreign travel, blood transfusion, or IV drug use was diagnosed with P. vivax malaria. She and her family had recently been camping in the panhandle’s Gulf County, and reported the mosquito activity as `intense’ (see MMWR report February 15, 1991 / 40(6);106-108).
- In 1996 (2 cases) and again in 2003 (8 cases) of locally acquired P. vivax malaria were detected in Palm Beach County (see Multifocal Autochthonous Transmission of Malaria --- Florida, 2003).
CDC is collaborating with two U.S. state health departments with ongoing investigations of locally acquired mosquito-transmitted Plasmodium vivax malaria cases. There is no evidence to suggest the cases in the two states (Florida and Texas) are related. In Florida, four cases within close geographic proximity have been identified, and active surveillance for additional cases is ongoing. Mosquito surveillance and control measures have been implemented in the affected area. In Texas, one case has been identified, and surveillance for additional cases, as well as mosquito surveillance and control, are ongoing. All patients have received treatment and are improving.
2023 Malaria Cases Acquired in Florida: In 2023, seven cases of locally acquired malaria have been reported in Sarasota County, with onsets in May, June (5), and July. The Plasmodium species reported were Plasmodium vivax.2023 Dengue Cases Acquired in Florida: In 2023, three cases of locally acquired dengue have been reported in Miami-Dade County, with onsets in January, March, and June. Three cases have been serotyped by PCR. Serotypes reported were DENV-3 (3).
Malaria can often present as a `flu-like' illness, and physicians are already on the alert for potential avian and swine flu cases (see COCA Call What Providers Need to Know about Zoonotic Influenza). Since most doctors have limited experience diagnosing and treating malaria, tomorrow the CDC will hold a COCA Call webinar for clinicians.
These presentations are often technical, and are of greatest interest to clinicians and healthcare providers, but also may be of interest to the general public.
Review of Malaria Diagnosis and Treatment in the United States
Overview
The Centers for Disease Control and Prevention (CDC) issued a Health Alert Network (HAN) Health Advisory on June 26, 2023, to share information on the recent identification of locally acquired, mosquito-transmitted malaria cases (P. vivax) in Florida and Texas. Although these are the first documented instances of locally transmitted malaria in the United States since 2003, approximately 2,000 malaria cases are diagnosed and treated in the United States each year, primarily in individuals returning from travel to malaria-endemic countries.
These malaria infections present a potential risk of subsequent transmission domestically since Anopheles mosquitoes capable of transmitting malaria are broadly distributed across the United States. During this COCA Call, participants will learn how to prevent, diagnose, and treat malaria, how the biology of the pathogen contributes to clinical management of the disease, and how CDC and state and local health departments are responding to the locally acquired mosquito-borne malaria cases in the United States.
Presenters
Alison Ridpath, MD, MPH
CAPT, U.S. Public Health Service
Medical Countermeasures Team Lead
2023 Malaria Response
Centers for Disease Control and Prevention
Erika Wallender, MD, MPH
LCDR, U.S. Public Health Service
Epidemic Intelligence Service Officer
Medical Countermeasures Team2023 Malaria Response
Centers for Disease Control and Prevention
LCDR Adam Rowh, MD
LCDR, U.S. Public Health Service
Epidemic Intelligence Service Officer
Medical Countermeasures Team
2023 Malaria Response
Centers for Disease Control and Prevention
Call Materials
Not available at this time. Please check back.
Call Details
When:
Thursday, July 20, 2023,
2:00 PM – 3:00 PM ET
Webinar Link:
Webinar ID: 161 811 2526
Passcode: 882719
Telephone:
+1 669 254 5252
+1 646 828 7666
One-tap mobile:
+16692545252,,1618112526#,,,,*882719#
+16468287666,,1618112526#,,,,*882719#
The surprising thing is that given the number of malaria diagnoses each year in the United States among travelers from endemic areas, that the number of local transmissions isn't higher. It apparently takes numerous opportunities - and just the right set of conditions - for Malaria (or Dengue, Zika, or CHKV) to become established.
Malaria is spread by the Anopheles mosquito, and of the roughly 70 species of mosquitoes that inhabit Florida, more than a dozen are of the genus Anopheles.
To spread locally, Malaria then needs a few lucky breaks.
First, a viremic individual must arrive in the region and be bitten by a female Anopheles mosquito. That, unfortunately, can happen fairly often in Florida.
After that bloodmeal the mosquito must then survive long enough for completion of sporogony ( the extrinsic incubation period - EIP), which while temperature dependent, usually takes at least 7 to 14 days (cite Malaria Journal).Until then, the mosquito is thought incapable of passing the parasite on to another host (see graphic below)
It takes just the right combination of an imported case providing a blood meal to the right kind of mosquito . . . that manages to survive long enough to incubate the parasite . . . and then that mosquito then goes on to feed on a new human host.
But of course, it happens.
With the increasing threat of mosquito-borne diseases around the world (see WHO DON: Geographical Expansion of Dengue and CHKV in the Region of the Americas), we can't afford to be complacent when we see small outbreaks such as is occurring in Florida right now.
The State of Florida offers the following advice for the public on how to protect themselves, and reduce the mosquito population.
