National Park Service Issues Guidelines Regarding New Mosquito-Borne Disease

A new, for the mainland United States, mosquito-born disease has been in the news lately, and the National Park Service has issued some background on the disease -- Chikungunya virus -- and how to deal with it.

In December 2013, the first locally-acquired cases of chikungunya fever in the Americas occurred among residents of Saint Martin (French side). Since December, chikungunya virus (CHIKV) – a virus transmitted by mosquitoes – has spread to 18 other nations/territories in the Caribbean and South America, where over 170,000 suspected and confirmed cases have been reported.

Puerto Rico and the U.S. Virgin Islands both confirmed their first locally-acquired cases of chikungunya fever in late May and early June, respectively. In the continental U.S., no locally-acquired cases have been reported, but several states have reported cases among travelers to the Caribbean.

Symptoms of chikungunya fever include high fever, headache, and severe joint pain; the disease is rarely fatal. As a vaccine is not available, the best strategy is to prevent mosquito bites. Park managers should educate employees and visitors about chikungunya fever and support/implement appropriate prevention measures.

Here are some basic facts about chikungunya:

* Viral disease transmitted to people by infected mosquitoes (Aedes species), which bite mainly during the day and can also transmit dengue virus.

* Chikungunya virus was first described in 1952 in Tanzania.

* Besides the Americas outbreak, large outbreaks have occurred since 2006 in Kenya, India, Indonesia, Thailand, and other Asian and African countries.

Symptoms of chikungunya fever:

* Symptoms usually begin three to seven days (range: one to twelve days) after being bitten by an infected mosquito.

* Up to 25 percent of people infected with CHIKV do not have any symptoms.

The most common symptoms are high fever (≥102°F) and severe joint pain. Joint pain is usually symmetrical and occurs often in hands and feet. In Makonde (African language), chikungunya means “that which bends," referring to the stooped appearance of patients in severe pain. Other symptoms include headache, muscle pain, rash, joint swelling, conjunctivitis, and nausea/vomiting.

* Deaths are rare and occur mostly in older adults.

Treatment for chikungunya fever:

* There is no specific treatment or vaccine for CHIKV.

* Medicines (avoid aspirin) can help relieve fever and joint pain.

* A person who has recovered from chikungunya is likely immune against repeat infections

Risk for complications:

* Most patients feel better within a week, although joint pain and other chronic symptoms (e.g. fatigue, depression) may persist for months to years.

* People at increased risk for severe disease include newborns exposed during delivery, older adults (≥65 years), and people with chronic medical conditions, such as diabetes, high blood pressure, and heart disease.

Prevention measures:

* Wear long-sleeved shirts and long pants.

* Use repellents containing 30% or less DEET or 19% picaridin on exposed skin (http://www.cdc.gov/westnile/faq/repellent.html).

* Wear permethrin-treated clothing, especially socks and pants (DO NOT treat skin with permethrin).

* Use bed nets, window/door screens, and indoor ceiling fans.

* Empty standing water from outdoor containers (e.g. flowerpots, tires, tarps).

* Avoid outdoor activity at dawn and dusk (peak biting time).

Anyone who thinks they might have chikungunya should see a healthcare provider and remain under a mosquito bed net for duration of fever to reduce the potential for infecting other mosquitoes. People at increased risk for severe disease should consider not traveling to areas with ongoing chikungunya outbreaks.

For up-to-date information on CHIKV and the outbreak in the Americas, go to the following webpages:

* U.S. Centers for Disease Control and Prevention (CDC) – http://www.cdc.gov/chikungunya/

* Pan American Health Organization (PAHO) – http://www.paho.org/hq/index.php?lang=en

* Caribbean Public Health Agency (CARPHA) – http://carpha.org/