November 1, 2021 | Week 42 | Volume 1 | Issue 16 |
|
Welcome to the Florida Disease Activity Update, from the desk of Dr. Jonathan Day! It is Clarke’s privilege to share Dr. Day's weekly analysis of arbovirus disease activity in Florida with mosquito control professionals across the state. Our shared goal with Dr. Day is to provide timely and actionable information that mosquito control programs can use to make operational decisions and protect the public from vector-borne diseases.
|
|
What's Ahead for this Newsletter?
We are nearing the end of the 2021 arboviral transmission season in Florida. Moving forward, our plan for this Newsletter is to publish weekly for the next couple of weeks, and then terminate the weekly publications for the remainder of 2021. We will publish a Year-End Summary for the Florida 2021 Arboviral Transmission Season in late December 2021. In late May 2022, we will publish a Year in Review for 2021 and then resume weekly Newsletter updates for the 2022 season. We continue to welcome your feedback and Questions from Reader submissions for future issues. Thank you for your readership and continued interest in this Newsletter!
|
|
Chris from Tampa asks: “How does Culex blood-feeding behavior affect the transmission of WNV in Florida?”
A*: There are currently 20 species of Culex reported in Florida. There is a wide variety of blood-feeding behaviors represented by these species. For example, three (Culex atratus, Cx. peccator, and Cx. pilosus) feed almost exclusively on reptiles and amphibians. Of the 20 Culex species, at least four (Cx. nigripalpus, Cx. quinquefasciatus, Cx. restuans, and Cx. salinarius) are likely important in the WNV transmission cycle, and two of those (Cx. nigripalpus and Cx. quinquefasciatus) are responsible for WNV transmission to humans. Several factors make these two species excellent vectors of WNV. First, they are abundant. Second, they are blood-feeding opportunists that feed on a variety of hosts. I have seen Cx. nigripalpus feed on cattle, horses, dogs, chickens, Bobwhite Quail, humans, and Cuban tree frogs. Finally, in the case of Cx. nigripalpus, there is a seasonal feeding shift from birds in spring and early summer to mammals in late summer and fall. This is the perfect storm for WNV amplification and transmission: start by feeding on birds, acquire WNV, and end the season by feeding on mammals, including humans.
|
|
THE WEEK IN REVIEW:
ARBOVIRAL TRANSMISSION IN FLORIDA
|
|
Low-level indicators of active arboviral transmission continued to appear in Florida during Week 42 of 2021. There were no changes from last week for EEEV or WNV transmission indicators. Seven new SLEV antibody-positive sentinel chickens were reported this week. One new travel-related DENV infection was reported this week. West Nile is the only arbovirus that currently threatens humans in Florida.
|
|
WHAT ARE WE CURRENTLY SEEING? |
|
 |
Eastern Equine Encephalitis (EEEV) Activity
There was no change in transmission of EEV in Florida during week 42 of 2021.
|
Find a review of 2020 EEEV activity in the archived Vol 1, Issue 1 report.
|
West Nile Virus (WNV) Activity
There was no change in transmission of WNV in Florida during week 42 of 2021.
|
Find a review of 2020 WNV activity in the archived Vol 1, Issue 1 report. |
Dengue (DENV) Activity
One (1) new travel-related dengue case was reported in Monroe County this week, bringing the total number of travel-related dengue cases reported in Florida during 2021 to 10 (Broward (1), Hernando (2), Hillsborough (1), Miami-Dade (3), Monroe (1), and Palm Beach (2) Counties). Reports of travel-related dengue cases in Miami-Dade and Monroe Counties are significant because during the past decade all locally-acquired dengue outbreaks began in South Florida. It will be important to monitor locally-acquired dengue cases during the next six months. Locally-acquired dengue cases reported early in the year (February-April) are indicators of increased risk for a widespread outbreak of locally-acquired dengue later in the year.
|
Find a review of 2020 DENV activity in the archived Vol 1, Issue 1 report.
|
St. Louis Encephalitis Virus (SLEV) Activity
Seven (7) new SLEV antibody-positive sentinel chickens were reported last week in Charlotte (1), Hillsborough (1), and Walton (5) Counties. This brings the total number of SLEV antibody-positive sentinel chickens reported in Florida during 2021 to 10. These recent seroconversions indicate a reintroduction and/or increased amplification of SLEV in the Florida Panhandle and along the west coast of Peninsular Florida, probably in migrating birds. It remains to be seen whether SLEV becomes re-established in pockets that can survive until the 2022 transmission season.
|
Find a review of 2020 SLEV activity in the archived Vol 1, Issue 1 report.
|
|
|
|
OPERATIONAL STRATEGIES TO CONSIDER |
|
Vector and arbovirus surveillance remains one of the most important tools that vector control agencies currently have at their disposal. Arboviral transmission indices (sentinel chickens, positive equines, positive exotics (i.e., emus), positive humans, and positive mosquito pools) provide indicators of local virus transmission, although sometimes not in a timely manner. Monitoring mosquito populations and their age structure provides added information about potential transmission risk. Additional vector control efforts in and around sites where virus transmission is known or suspected of recently occurring provides another potential mechanism to mitigate viral transmission.
The Florida regions with the highest current concern for arboviral transmission are those where indicators of EEEV transmission (sentinel chickens and EEE-positive equines) continue to be reported. These include all North Florida Counties and all of the Panhandle Counties, especially those around Walton County. In addition, recent intense WNV transmission to sentinel chickens in South Florida and the Florida Panhandle indicates an increased risk of WNV to equines and humans during the next eight weeks in this region of Florida.
|
|
Jonathan Day, Professor Emeritus of Medical Entomology from the University of Florida, is a national expert on mosquitoes and other blood-feeding arthropods that transmit diseases to humans, domestic animals, and wildlife. In collaboration with other researchers, Dr. Day has developed an effective system for monitoring and predicting epidemics of mosquito-borne diseases.
|
|
Acknowledgments: This analysis would not be possible without the tireless efforts of multiple agencies across Florida. At least 27 Florida agencies collect serum samples from sentinel chickens each week and mail them to the Florida Department of Health Tampa Branch Laboratory for analysis and reporting. Data are summarized by researchers at the Florida Department of Health in Tallahassee and reported weekly as the Florida Arbovirus Surveillance report.
Contributors to this summary and full report include: Andrea Morrison, PhD, MSPH, Rebecca Zimler, PhD, MPH, and Danielle Stanek, DVM, Florida Department of Health, Bureau of Epidemiology; Lea Heberlein-Larson, DrPH; Alexis LaCrue, PhD, MS; Maribel Castaneda, and Valerie Mock, BS, Florida Department of Health Bureau of Public Health Laboratories, and Carina Blackmore, DVM, PhD, FDOH Division of Disease Control and Health Protection. And, Dr. Rachel Lacey, Florida Department of Agriculture and Consumer Services, Animal Disease Diagnostic Laboratory in Kissimmee, FL.
Daily updates of the Keetch-Byram Drought Index (KBDI) are produced by the Florida Department of Agriculture and Consumer Services, Forest Service and are posted at: fireweather.fdacs.gov/wx/kbdi_4km.html.
All of the graphics used in this Newsletter were designed and developed by Gregory Ross.
*The question this week was answered with the assistance of Dr. Lawrence Reeves at the Florida Medical Entomology Laboratory in Vero Beach.
|
|
Clarke has been helping make communities more livable, safe and comfortable since 1946.
Learn more about our work in protecting public health on clarke.com.
|
|
|
|
|
|
|
