Credit CDC
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Two vector-borne disease outbreaks we’ve been following for the past couple of months have been the introduction of the Chikungunya virus (CHKV) to the Americas (see Chikungunya Update & CDC Webinar Online) and the spread of the Zika Virus (ZIKAV) in French Polynesia (see Zika, Dengue & Unusual Rates Of Guillain Barre Syndrome In French Polynesia).
Both viruses are spread by mosquitoes, and both – aided and abetted by increased international travel and trade – have expanded their geographic range considerably in recent years.
The risks of CHKV introduction was considered great enough that in 2011, the CDC and PAHO (Pan American Health Organization) put together a 161-page guide on preparing for the arrival of Chikungunya to the Americas (see Preparedness and Response for Chikungunya Virus Introduction in the Americas).
Today’s ECDC Communicable Disease Threats Report (CDTR), week 11/2014 – dated 17 Mar 2014 – has updates on both of these outbreaks, along with updates on MERS-CoV, Polio, H7N9, Dengue, and Influenza.
Chikungunya outbreak - The Caribbean, 2013-2014
Opening date: 9 December 2013 Latest update: 14 February 2014
Epidemiological summary
Cases reported as of 06 March 2014:
- Virgin Islands (UK), 6 confirmed cases;
- Saint Martin (FR), 2 030 suspected and 765 confirmed or probable cases;
- Sint Maarten (NL), 115 confirmed autochthonous cases;
- Martinique, 3940 suspected and 1058 confirmed or probable cases;
- Saint Barthélemy, 380 suspected and 127 confirmed or probable cases;
- Guadeloupe, 1 460 suspected and 476 confirmed or probable cases;
- Dominica, 56 confirmed cases (imported) and 91 autochthonous cases;
- French Guiana, 17 confirmed cases, 10 of which are autochthonous cases;
- Anguilla, 14 confirmed cases on the island with one case probably originating from Saint Martin;
- Aruba, one imported case originating from Sint Maarten;
- St. Kitts and Nevis one confirmed case.
ECDC assessment
Epidemiological data indicate that the outbreak, which started in Saint Martin (FR), is expanding. An increasing number of cases have been observed from most of the affected areas. The vector is endemic in the regions, where it also transmits dengue virus. Vigilance is recommended for the occurrence of imported cases of chikungunya in tourists returning to the EU from the Caribbean, including awareness among clinicians, travel clinics and blood safety authorities.
The autochthonous cases in French Guyana are the first autochthonous chikungunya cases in mainland South America.
Zika virus infection outbreak - The Pacific - 2013-2014
There is an ongoing outbreak of Zika virus (ZIKAV) infection in the Pacific affecting two French overseas territories (French Polynesia and New Caledonia) and Easter Island. This is the second documented outbreak of ZIKAV infection reported in the Pacific. It is estimated that more than 29 000 cases have sought medical care with Zika-like symptoms in French Polynesia since the beginning of the outbreak in October 2013. There is a simultaneous dengue outbreak in the region. The French Polynesian health authorities report a concurrent significant increase in neurological syndromes and autoimmune illnesses. The cause and possible links with Zika or dengue virus infections are being investigated.
Opening date: 9 January 2014 Latest update: 6 March 2014Update of the week
There is no new update since last week from French Polynesia. As of 21 February there were more than 8 500 suspected cases. There have been 74 cases of neurological and auto-immune complications of which 41 cases were Guillain-Barré syndrome. The outbreak is declining in the majority of the islands.
In New Caledonia, an additional 31 autochthonous cases of Zika virus (ZIKAV) infection were reported during the past week. As of 5 March 2014, 171 confirmed cases have been reported, of which 139 were autochthonous. There are no reports of neurological complications.
One case of ZIKAV was reported from Easter Island, a Chilean territory located in the Pacific Ocean, with a date of onset on 11 February 2014. Forty suspected cases meeting the case definition used for the surveillance of Zika virus infection in Chile have been identified through a retrospective investigation on Easter Island. This is the first report of locally acquired ZIKAV infection in the Americas.
ECDC assessment
This is the first documented outbreak of ZIKAV infection in French Polynesia and New Caledonia and the first autochthonous case of ZIKAV infection in the Americas. ZIKAV infection is considered an emerging infectious disease with the potential to spread to new areas where the Aedes mosquito is present. There is a risk for the disease spreading further in the Pacific and to the countries of the Americas where the vector is present, and for sporadic imported cases in Europe from endemic areas. Vigilance must be enhanced towards imported cases of ZIKAV infection in the EU Member States and EU overseas countries and territories and outermost regions, in particular where effective vectors are present. Early detection of cases is essential to reduce the risk of autochthonous transmission. Clinicians and medical travel clinics should be aware of the situation in the Pacific islands and include ZIKAV infection in their differential diagnosis. There is no available vaccine against ZIKAV infection. Travellers can protect themselves by preventing mosquito bites.
ZIKAV infection is a mild illness and has not been known to have neurological complications. The reported complications in French Polynesia are not confirmed to be caused by ZIKAV infections. However, there is a temporal association with the simultaneous outbreaks of ZIKAV and dengue. It is important to determine the cause of this increase and a possible association with the ongoing transmission of DENV-1, DENV-3 and ZIKAV.
The West Nile Virus arrived in New York in the late 1990s, and in a matter of a few short years spread across the continent (see CDC West Nile Update) and now infects thousands of people each year.
In 2007 a traveler returning from a visit to India imported the Chikungunya virus to Northern Italy (see It's A Smaller World After All) where it went on to infect nearly 300 people in the province of Ravenna before it was brought under control.
And Dengue fever, not seen in the United States for 60 years, returned to South Florida in 2009, likely carried by an international traveler (see (see MMWR: Dengue Fever In Key West), and is now making inroads in Texas as well.
All examples of how quickly imported mosquito-borne illnesses can set up housekeeping in new regions of the world.
Now, with the Chikungunya virus literally on our doorstep, officials worry that it is only a matter of time before we begin to see outbreaks here in the United States (see WSJ report Approach of Mosquito-Borne Virus Has U.S. on Alert). And given the scope of air travel today, the relatively remote location of the ZIKAV outbreak in the South Pacific holds no guarantee that it won’t make its way to our shores as well.
Unlike much of the rest of the nation, much of which is still engulfed in winter, spring has already sprung in Florida and our mosquito season is soon to begin.
The overall risk of contracting a mosquito-borne illness anywhere in the United States remains very small, but with no vaccines available, and scattered cases of Dengue (along with West Nile, EEE, SLEV, and other rare arboviral threats) Florida’s Health departments continue to urge people to remember to follow the `5 D’s’:
Good advice in Florida this during this spring and summer, and anyplace else mosquitoes can be found.
