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Chikungunya - Dealing With Uninvited Guests: Mosquitoes

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  • Chikungunya - Dealing With Uninvited Guests: Mosquitoes

    hat tip Michael Coston

    Sunday, June 15, 2014

    Dealing With Uninvited Guests

    Aedes Albopictus ? Asian Tiger Mosquito

    # 8746

    YesterdayDr. Jen Halverson left a highly informative comment on my PAHO Chikungunya Update blog, which describers here impressions of the outbreak in Haiti, and is deserving of additional exposure.
    The situation is Haiti is, as you said, very badly underreported. I got chikungunya (confirmed by testing in the US) on 5/14. I was one of the first cases among my friends. The vast majority of my ex-pat friends in Port au Prince have had it. Other cities are very affected as well. The majority of my Haitian friends and colleagues have already had it. My conservative estimate for Haiti is at least a million cases so far, and probably more. We will obviously never know the true numbers. I have been working in Haiti for 16 years (I'm an ER doctor) and I've never seen anything like this.
    My thanks to Dr. Halverson for this sobering first hand report, and for the work she does under difficult conditions.

    Her account is all the more concerning as the rainy season in Haiti is really just getting underway. While tropical temps abound year-round, the rainy season runs from May through October, and can be greatly exacerbated by tropical storms and hurricanes which most often arrive in August and September.
    It is worth noting that this first Chikungunya outbreak began in late November of last year, after the end of the traditional rainy season, and has spread with remarkable efficiency during what are considered the driest 6 months of the year.
    As you can see by the following CDC chart for Puerto Rico, dengue (which is spread by the same types of mosquitoes as Chikungunya), usually peaks in late September, during the height of the rainy season.

    Given the Chikungunya outbreak in the Caribbean, public health departments here in Florida and around the United States, are urging people to be more diligent about removing breeding places for mosquitoes around their homes.
    But it isn?t just outside the home where people need to check . . . some mosquito species are perfectly capable of setting up light housekeeping inside the home as well.

    While the Aedes aegypti has long been associated with spreading nasties such as yellow fever, dengue and Chikungunya, in 2005 a mutation in the envelope protein gene (E1-A226V) of the Chikungunya virus was credited with allowing Aedes Albopictus or `Asian tiger? mosquito to transmit the virus efficiently (see A Single Mutation in Chikungunya Virus Affects Vector Specificity and Epidemic Potential).
    An important development in that the `Asian tiger? mosquito is both well distributed around the world, and that it is a very aggressive daytime biter.
    While most often found outdoors, research has shown that the Ae. albopictus lives longer, may exhibit increased nighttime biting activity, and produces more offspring when living in an indoor environment (see PLoS One Indoor-Breeding of Aedes albopictus in Northern Peninsular Malaysia and Its Potential Epidemiological Implications).
    Although this particular study was set in Malaysia, the Aedes albopictus mosquito has made extensive inroads in the rest of the world over the past 40 years, and is considered one of the top 100 worst invasive species according to the Global Invasive Species Database.

    Dark Blue indicates the A. Albopictus native range, while green indicates new introductions in last 40 years.
    Having lived aboard a sailboat in the Florida keys around the Everglades, I can assure you that well-fitted screens are your most important barrier against indoor mosquitoes. Yet, despite your best efforts, some may still get inside.

    Since mosquito larvae can grow in as little as a tablespoon of water, it is important to considerindoor potted plants, and other places where stagnant water may exist, as well as outdoor breeding places. Aedes mosquitoes have been been found breeding in such unusual places as Waterpiks, fridge trays, and seldom usedtoilets (according to the Miami Herald Mosquitoes carrying dengue fever can live indoors).

    Source - Mosquito Control Measures CHIK (2.0 MB PDF)

    Given the risks posed by Chikungunya and dengue (and that of other mosquito borne diseases in the U.S., like WNV, EEE, & SLEV), it makes sense to take proactive mosquito prevention steps to protect you and your family.
    So today would be a good day to go around and look for likely breeding places in, and around your home. This should become a weekly habit ? at least during mosquito season.

    And to help you with warding off these pests, we?ve an interactive insect repellant search engine developed by the EPA that will that will allow you to input your needs and it will spit out the best repellants to use.

    (click image to go to search engine)

    And a final note, if you live in the United States (and this presumably is valid in other places as well), and you are seeing an unusual number of mosquitoes in your neighborhood, call your local mosquito control board and report it. Quite often they will respond to your request by dispatching inspectors to look for, and eliminate, nearby breeding places.

    Posted by Michael Coston at <a class="timestamp-link" href="" rel="bookmark" title="permanent link"><abbr class="published" itemprop="datePublished" title="2014-06-15T08:13:00-04:00">8:13 AM</abbr>