One of two highly competent vectors in the Americas
# 3640
Although its arrival had long been predicted, up until late last year, the mosquito-transmitted disease Chikungunya had never been locally transmitted in Western Hemisphere. All that changed when we saw two confirmed cases on the French Part of St. Martins, in the Caribbean, announced last December.
At that time, there were also four probable and twenty suspected cases of chikungunya on the island.
Within a month (Jan 10th), the ECDC issued an update indicating nearly 300 probable or confirmed cases, and the disease had spread to Saint Martin (NL), Martinique, Saint Barthélemy, Guadeloupe and French Guiana.
Six weeks after that, the numbers had spiked to 6,000 probable or confirmed cases, and the CHKV virus had spread to more islands, and even to South America (see Feb 21st ECDC Epidemiological Update: Chikungunya Spreads In Caribbean And Into South America).
Since then we’ve seen a CDC Webinar On Chikungunya to alert clinicians of the signs of infection, analysis of Chikungunya’s Growing Threat To The Americas, and taken a long look at the State of Florida’s plans to deal with the anticipated arrival of this viral foe in Florida Prepares For Chikungunya.
Today, the ECDC’s latest report indicates that the number of probable cases has now grown to more than 40,000 since last December, including 7 deaths. (see The full Communicable Disease Threats Report week 13/2014)
Chikungunya outbreak - The Caribbean, 2013-2014
This is the first documented outbreak of chikungunya with autochthonous transmission in the Americas. As of 25 April 2014, there have been more than 40 000 probable and confirmed cases in the region. Seven fatalities have been reported so far.
Opening date: 9 December 2013 Latest update: 15 May 2014
Update of the week
During the past week, new cases have been reported in most of the affected areas. In the French Antilles, the number of new cases is generally decreasing or constant. In French Guiana, the number of autochthonous cases is increasing and the virus circulation is intensifying and new emerging clusters have been identified. Increased transmission is reported by the Dominican Republic. Media quoting the Department of Health reports a substantial increase of cases in Haiti (LINK). Antigua and Barbuda, British Virgin islands and Saint Lucia have reported additional cases (CARPHA).
To date, islands with confirmed cases are Saint Martin/Sint Maarten, Martinique, Saint Barthélemy, Guadeloupe, British Virgin Islands, Anguilla, Dominica, Aruba, Saint Kitts and Nevis, Saint Lucia, Saint Vincent and the Grenadines, Dominican Republic, Haiti, Antigua and Barbuda, and French Guiana in mainland South America (WHO). In most of the territories of the French Antilles, given the caseload, the health authorities decided not to seek laboratory confirmation for all suspected cases.
CHKV in the Caribbean – Source ECDC
Chikungunya isn’t naturally endemic in mosquitoes, it has to be introduced to a local mosquito population by a viremic host – and in this case – the hosts are tourists or travelers coming from another region where the virus is already prevalent.
The mosquitoes acquire the virus during a blood meal on an infected individual, and then carry the virus on to their next victim.
Last fall it is likely that one or more infected travelers arrived in the Caribbean and unwittingly seeded the virus into the local mosquito population. This is how Dengue turned up in Key West (after an absence of 60 years) in 2009, and how West Nile Virus was likely introduced into North America in 1999.
North America is home to two efficient vectors – the Aedes aegypti & Aedes albopictus mosquitoes – which has led to concerns that climate change, and increased international travel, could lead to introduction (or re-introduction) of a number of very nasty mosquito-borne pathogens – including Dengue, Malaria, and Chikungunya (see Preparedness and Response for Chikungunya Virus Introduction in the Americas)..
Last week, in a press release, the Florida Department of Health advised that 3 Chikungunya cases were imported into Florida, although we’ve yet to see any local transmission of the virus. Some excerpts from that statement follow:
Department Raises Awareness of Chikungunya Fever
FOR IMMEDIATE RELEASE Contact: DOH Communications
May 16, 2014 (850) 245-4111
FLORIDA DEPARTMENT OF HEALTH RAISES AWARENESS OF CHIKUNGUNYA FEVER
TALLAHASSEEThe Florida Department of Health advises residents and visitors to be aware of chikungunya fever, a viral mosquito borne disease that has made its way to the Caribbean countries from Africa, Asia and islands in the Indian Ocean and Western Pacific. Travelers to these countries could carry the virus back to the United States and infect local mosquito populations.
“With a large number of people travelling to and from the Caribbean in Florida we have been monitoring for possible imported cases,” said Dr. Carina Blackmore, State Public Health Veterinarian and Deputy State Epidemiologist. “We encourage all Floridians to practice the drain and cover method to minimize mosquito exposure.”Mosquitoes can transmit different viruses including chikungunya, West Nile and Eastern equine encephalomyelitis. Chikungunya, like dengue, can be transmitted from an infected human to an Aedes mosquito which in turn can bite another human and pass along the disease. Aedes mosquitoes are day biters which can lay eggs in very small water containers. Early detection of the symptoms and preventing mosquitoes from biting will help prevent the disease from spreading in the United States. During times of increased mosquito activity, local mosquito control districts will treat accordingly to ensure the safety of communities.
The Department has received three reports of imported cases of chikungunya fever to Florida from travelers who recently traveled to the Caribbean. One case is a 30 year old woman in Miami-Dade County, one case is a 29 year old woman from Broward County, and the other is a 44 year old woman in Hillsborough County.
Symptoms of chikungunya usually begin 3-7 days after being bitten by an infected mosquito and can include fever and severe joint pains often in hands and feet. Other symptoms can include headache, muscle pain, joint swelling or rash. Chikungunya fever does not often result in death, but some individuals may experience persistent joint pain. There is currently no vaccine or medication to prevent chikungunya fever.If you feel that you may have contracted chikungunya, see your health care provider. People at increased risk for severe disease include newborns exposed during delivery, older adults (≥65 years), and people with medical conditions such as high blood pressure, diabetes, or heart disease. A person infected with chikungunya should stay indoors as much as possible until symptoms subside to prevent further transmission.
While the overall risk of contracting a mosquito-borne illness anywhere in the United States remains very small, with no vaccines available, and scattered cases of Dengue, West Nile Virus, EEE, SLEV, and now the specter of Chikungunya arriving in the near future - Florida’s Health departments urge people to always follow the `5 D’s’:
Good advice in Florida this during this spring and summer, and anyplace else mosquitoes can be found.
