Avian Flu Diary: Chikungunya: A Matter Of Some (More) Import

CHKV in the Caribbean – Source ECDC

Photo Credit- CDC

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Two weeks ago the Florida Department of Health announced that three imported cases of Chikungunya had been reported in the state this year (see press release). Countries of origin were Dominica, Dominican Republic, and Haiti while the Florida counties reporting cases were Broward, Hillsborough, and Miami-Dade.

While no local transmission of this mosquito-borne illness has been reported in Florida, the concern is that a traveler who arrives and is viremic (has active virus in their bloodstream), could infect a hungry mosquito who could then go on to spread it to others.

Which is precisely how Dengue fever found its way back to Florida in 2009 after an absence of 6 decades. Since then, Florida has been fighting sporadic outbreaks of the virus (see Florida: Dengue Forces Suspension Of Blood Donations In Two Counties). Last November we even saw a case of Locally Acquired Dengue In New York City.

The same mosquitoes (Aedes Aegypti and Aedes Albopictus) that carry dengue and malaria, also can transmit Chikungunya, and both can be found not only in Florida, but across wide swaths of the United States, Central, and South America.

In just 6 months we’ve watched Chikungunya go from a handful of cases on the French Part of St. Martins to more than 60,000 confirmed and probable cases spanning most of the Caribbean (see ECDC: Caribbean Chikungunya Update). This extraordinary spread has raised serious concerns that Florida, and perhaps other areas of the United States, are at risk this summer as well.

Although we’ve seen sporadic introductions of viremic CHKV infected travelers to the United States in the past (see 2011 CID Journal report Chikungunya Fever in the United States: A Fifteen Year Review of Cases), those numbers have been small (109 between 1995- 2009), and so far (unlike dengue and WNV), we haven’t seen any evidence of local transmission.

Imported CHKV in Florida – FL DOH

But with each introduction by a viremic traveler, the chances of forward transmission go up. And today, Florida’s Arbovirus Surveillance report (date May 24) announced 7 more imported Chikungunya cases were detected over the past week – along with 2 imported malaria cases and 1 imported dengue case.

Florida Arbovirus Surveillance Week 21: May 18-24, 2014

Imported Dengue: Twenty three cases of dengue with onset in 2014 have been reported in individuals with travel history to a dengue endemic country in the two weeks prior to onset. Countries of origin were: Bolivia, Brazil (2), Cuba (8), Dominican Republic (4), Guadeloupe, Honduras, Puerto Rico (3), Trinidad, and Venezuela (2). Counties reporting cases were: Alachua, Broward (2), Clay, Hillsborough (3), Marion, Miami-Dade (10), Orange, Osceola (3) and Seminole. Four of the cases were reported in non-Florida residents.

In 2014, 16 of the 22 cases of dengue reported in Florida have been serotyped by PCR. Additional serotyping and strain typing are being conducted.

Imported Chikungunya: Ten cases of chikungunya with onset in 2014 have been reported in individuals with travel history to a chikungunya endemic country or area experiencing an outbreak in the two weeks prior to onset. Countries of origin were: Dominica, Dominican Republic, Haiti (6), and Martinique (2). Counties reporting cases were: Broward, Hillsborough (2), Miami-Dade (5), Palm Beach, and Pasco.

Imported Malaria: Thirteen cases of malaria with onset in 2014 have been reported. Countries of origin were: Angola, Dominican Republic, Equatorial New Guinea (2), Ghana, Guatemala, Ivory Coast (2), Kenya, Sierra Leone (2), Sudan, and Uganda. Counties reporting cases were: Broward (3), Duval, Hernando, Hillsborough (2), Miami-Dade, Okaloosa, Orange, Osceola, Pasco, and Santa Rosa. One of the cases was reported in non-Florida residents.

Nine cases (69%) were diagnosed with Plasmodium falciparum. Two cases (15%) were diagnosed with Plasmodium vivax.One case (8%) was diagnosed with Plasmodium malariae. One case (8%) was diagnosed with Plasmodium Ovale.

Chikungunya – while rarely fatal - can cause prolonged fever and severe polyarthralgias (joint pain) in a high percentage of those infected. The disease usually runs its course in 10 days to 2 weeks, but in some cases can last for months or years. It is definitely not an illness you want to experience.

People who are diagnosed with chikungunya are advised to stay indoors as much as possible until symptoms subside to prevent spreading the virus, but of course, not every case is severe enough to warrant seeing a doctor, and not every case ends up getting properly diagnosed.

Last month in Study: Chikungunya’s Growing Threat To The Americas, we looked at predictions that CHKV might be coming to a mosquito near you, an eventuality anticipated by the CDC/PAHO three years ago in their 161-page guide on preparing for the arrival of Chikungunya to the Americas (see Preparedness and Response for Chikungunya Virus Introduction in the Americas).

The overall risk of contracting a mosquito-borne illness anywhere in the United States remains very small, and thus far, we’ve not seen local transmission of Chikungunya in America. But with no vaccines available, and sporadic cases of West Nile Virus, Dengue, EEE, SLEV reported each year - and now the specter of Chikungunya arriving in the near future – local Health departments urge people to always follow the `5 D’s’ of prevention: