May 10, 2023 | Volume 3 | Issue 4 | As of Week 18

A QUESTION FROM OUR READERS

Q. Gin from Newburyport, MA, asks: “How in the world did Culex lactator get its name?”

A*. We’ve been scratching our heads and asking the same question for months.

Thanks to some excellent sleuthing by Dr. Roxanne Connelly at the CDC in Ft. Collins, CO, we now know the answer, and I will liberally quote from her written answer. Culex lactator was named a new species by Dyar and Knab in 1906. This mosquito is not known to lactate or drink milk. Species names should be in Latin and are typically associated with someone who initially found or described the species, some morphological character unique to the species, or something related to habitat or locale, and sometimes they are named for spouses or mentors. As a rule, the name should not be offensive. Harrison G. Dyar, Jr. and Fredrick Knab named many Culex species in a manner that does not follow the abovementioned pattern. These include Culex conservator, Cx. conspirator, Cx. coronator (Figure 1), Cx. declarator, Cx. decorator, Cx. derivator, Cx. educator, Cx. elevator, Cx. extricator, Cx. gravitator, Cx. habilitator, Cx. inhibititator, Cx. interrogator, Cx. investigator, Cx. janitor, Cx. lamentator, Cx. mortificator, Cx. mutator, Cx. proclamator, Cx. regulator, Cx. rejector, Cx. restrictor, and Cx. simulator.

In Marc Epstein’s 2016 biography of H.G. Dyar: Moths, myths, and mosquitoes: the eccentric life of Harrison G. Dyar, Jr., he notes that Dyar used names for many species that appear to be more related to humans and human endeavors than the classical naming protocol. Epstein suggests that the “ator” endings are puns referring to people in and out of the mosquito business. For example, a mosquito control technician would be a regulator, and a mosquito taxonomist would be an investigator. Epstein notes three of the names, Cx. decorator, Cx. habilitator, and our very own Cx. lactator, are possibly poking fun at “early twentieth‐century women.” Epstein’s biography is interesting and full of drama, lawsuits, secret lives, and professional jealousy.

Two final thoughts. Larry Reeves thinks that Cx. janitor is a pun suggesting that the job of taxonomists (both Dyar and Knab) is to clean up everyone else’s messes. And Roxanne points out that Dyar and Knab would not have gotten away with this mosquito species naming scheme in modern times.

A BONUS QUESTION FROM OUR READERS

Q. Dr. Baker from Vero Beach, FL asks: “What species of travel-related malaria have been reported in Florida so far in 2023?”

A. According to the Florida Arbovirus Surveillance Report for Week 18 (April 30-May 6, 2023), six of the 12 travel-related human malaria cases reported in Florida are Plasmodium falciparum, four are P. vivax, and two are P. malariae. Countries of origin include: Burundi, Democratic Republic of the Congo, Equatorial Guinea, Ghana, Kenya, Nicaragua, Sierra Leone and Sudan.

THE CURRENT OUTLOOK FOR ARBOVIRAL TRANSMISSION IN FLORIDA

Arboviral transmission has continued at a slow pace in Florida during the 2023 transmission season. The South Florida avian nesting season is in full swing. Four important arboviral amplification hosts (Blue Jays, Common Grackles, Mourning Doves, and Northern Cardinals) are all nesting in Indian River County.  

Rainfall patterns so far this year favor EEEV transmission in North Central Florida (see the answer to A Question From Our Readers in Volume 3, Issue 1 of the Newsletter) and WNV transmission in South Florida (see the answer to A Question From Our Readers in Volume 3, Issue 2 of the Newsletter).  

Imported cases of dengue continue to be reported in Florida, with the majority, 49/67 (73%), in travelers from Cuba. The Dengue 3 serotype continues to predominate, 42/67 (63%), in travel-related cases. As of week 18 in 2022, 17 travel-related dengue cases were reported in Florida compared with the 67 cases reported so far this year. The imported dengue cases continue to pose a threat of outbreaks of locally-acquired dengue throughout South Florida. Table 1 summarizes the current status of arboviral transmission in Florida.

Table 1. Summary of mosquito-borne disease transmission and imported cases in Florida as of May 6, 2023.

Dengue Viruses

Imported cases of dengue continue to be reported in Florida (Figure 2).

Figure 2. The spatial distribution of imported human dengue cases in Florida as of early May, 2023. Counties shaded red indicate sites of at least one imported case during the past two weeks.

Recently imported dengue cases increase the risk of locally-acquired dengue transmission, and vector control personnel in the two Florida counties shaded red in Figure 2 should be alert to the possibility of locally-acquired dengue transmission in the coming weeks. Two locally-acquired dengue cases have been reported in Miami-Dade County so far in 2023. 

Malaria

Twelve imported human malaria cases have been reported in Florida in 2023. These include single introductions into Broward, Duval, Hillsborough, and Osceola Counties. Two travel-related cases have been reported in Leon and Pinellas Counties, and four have been reported in Miami-Dade County. Locally-acquired human cases of malaria usually appear in Florida after mid-July.

Eastern Equine Encephalitis Virus

North Central Florida is currently the region where transmission of EEEV will most likely occur in the coming months. Seventeen EEEV antibody-positive sentinel chickens (Figure 3) and four EEEV-positive equines (Figure 4) have been reported in Florida in 2023.

Figure 3. The spatial distribution of EEEV antibody-positive sentinel chickens in Florida as of early May, 2023.

Figure 4. The spatial distribution of EEEV-positive equines in Florida as of early May, 2023.

West Nile Virus

There has been little evidence of WNV transmission in Florida as of this report. Four WNV antibody-positive sentinel chickens have been reported in Hillsborough (two positives), Orange, and Walton Counties thus far in 2023. One WNV-positive equine was reported in Hernando County in early January.

It is still too early in the 2023 Florida arboviral transmission season to make meaningful predictions about disease transmission later in the year. 

Imported dengue cases continue to be reported in Florida at a rate surpassing the 2022 introductions as of Week 18, so the possibility of emerging foci of locally-acquired dengue must be closely monitored. Vector control agencies in Volusia and Miami-Dade Counties should be aware of the recently imported dengue cases and the possibility that these may result in locally-acquired dengue cases in the coming weeks. 

Environmental conditions in North Florida currently favor EEEV transmission, but there are no indications of an imminent major outbreak. West Nile virus and SLEV transmission is currently low, although the environmental conditions in South Florida favor enhanced mid-summer Flavivirus transmission. 

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, compilation 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.

All of the graphics used in issues of this Newsletter are designed and developed by Gregory Ross.

The Newsletter is edited and distributed by Linda McDonagh.

*The first Question From Our Readers was answered this week in collaboration with Dr. Roxanne Connelly at the CDC in Ft. Collins, CO and Dr. Lawrence Reeves at the Florida Medical Entomology Laboratory in Vero Beach.