Texas health officials confirm first case of new mosquito-borne virus
The Texas Department of State Health Services (DSHS) confirmed the state’s first human case of chikungunya, a viral disease that can cause fever and severe joint pain and is spread to people by mosquitoes.
The Williamson County (near Austin) resident recently returned to Texas from a trip to the Caribbean, where chikungunya has been causing human disease since late 2013, a July 7 DSHS release states.
To date, no local spread of the virus has been reported in the continental United States, the release states, though imported cases make local spread possible because the mosquitoes that can transmit the virus are found in Texas.
As of July 8, 2014, in the United States, 138 travel-associated cases of chikungunya virus have been reported to ArboNET, the national surveillance system for arthropod-borne diseases, including 1 in Texas.
Although a DSHS release states that infections are rarely fatal, Dr. Ashwini Kucknoor, assistant professor of biology at Lamar University, said chikungunya, common in her native country of India, killed her friend’s mother.
“In older adults with high blood pressure, etc., it complicates things,” Kucknoor said. “There have been several deaths in India.”
Chikungunya, which originated in Africa, can cause severe joint pain, high fever, head and muscle aches, joint swelling and rash. Symptoms usually begin three to seven days after a mosquito bite. There is no vaccine or treatment for the virus.
“People have become bedridden because of severe joint ache,” Kucknoor said. “It’s hard to tell whether it is body ache or joint ache; it is all over. Kucknoor said the pain is described in her mother tongue, Kannada, as “back breaking.”
Most people feel better within a week, a DSHS report states, though some people may develop longer-term joint pain.
“Recovery is case dependent, or general health dependent,” Kucknoor said. “If you are already susceptible and weak, it may take longer – a week or even 15 days.”
Chikungunya is not transmitted from direct person-to-person contact, but a person with the disease can be the source of the virus for mosquitoes that can then transmit the virus to others through a bite.
“It’s so easy for us here in Texas to get bitten by a mosquito,” Kucknoor said. “The main problem with this virus is that the mosquito species that caries this virus is not the one that you see at dawn and dusk.”
No specific antiviral treatment is available for chikungunya fever. Treatment is generally palliative and can include rest, fluids and use of analgesics and antipyretics. Because of similar geographic distribution and symptoms, patients with suspected chikungunya virus infections also should be evaluated and managed for possible dengue virus infection.
Dengue, an infectious tropical disease caused by an arbovirus, is transmitted primarily by the same mosquitoes that transmit chikungunya and is characterized by high fever, rash, headache, and severe muscle and joint pain. Last year, Texas health officials confirmed a wave of dengue fever in South Texas.
Because the symptoms are similar, DSHS encourages physicians to consider both chikungunya and dengue infection in patients with acute onset of fever and joint pain and who have recently visited areas where at least one of the viruses is present.
Health professionals must rule out dengue and malaria before diagnosing chikungunya, Kucknoor said.
“You have to rule out infectious diseases out one by one,” she said.
People infected with chikungunya or dengue virus should be protected from further mosquito exposure during the first few days of illness to prevent other mosquitoes from becoming infected and reduce the risk of local transmission.
The virus is transmitted by two species of mosquito — the Aedes aegypti, also known as the yellow fever mosquito, and the Aedes albopictus, also known as the Asian tiger mosquito.
Although both species can be found here in Southeast Texas, Jefferson County Mosquito Control District (JCMCD) director Kevin Sexton said currently, it isn’t a huge concern.
“Right now I don’t think it is a very big threat,” Sexton said. “It’s fairly new to the country and brought mainly by people who travel here. This is the first case I’ve heard anywhere close to us.”
And Southeast Texans can do their part to control the population of these chikungunya-carrying mosquitoes, Sexton said.
“These are the ones that people tend to raise in their backyards and don’t even realize it,” he said. “They like to breed in birdbaths and gutters — in anything that can hold water around your yard.
JCMCD, which tests for West Nile Virus on a regular basis, currently has no way to test mosquito populations for chikungunya, Sexton said, adding that Jefferson County has received no positive West Nile Virus tests so far this year.
Following a spell of rainfall, there was increased mosquito activity last week, Sexton said, especially in west Jefferson County (China, Nome) and last weekend in southeast Jefferson County (Mid-County), but the activity has decreased following treatment of these areas.
“We’ve done quite a bit of spraying,” he said. “I got the (mosquito) counts today, and they’ve gone down quite a bit. They are tapering off a little bit following the aerial spraying.”
DSHS encourages people to protect themselves from mosquito bites at home and while traveling. Precautions include:
• Use an approved insect repellent every time you go outside and follow label instructions
• Drain standing water where mosquitoes can breed
• Wear long sleeves and pants when outside
• Use air conditioning or make sure doors and windows are screened to keep mosquitoes outside
As an additional measure, Kucknoor said in India residents sleep with a mosquito bed net. Some mosquito bed nets are even treated with insecticide, according to the CDC website, and are even more effective. These nets are available for purchase from online retailers.
“The insecticides that are used for treating bed nets kill mosquitoes, as well as other insects,” the CDC website states. “The insecticides also repel mosquitoes, reducing the number that enter the house and attempt to feed on people inside. In addition, if high community coverage is achieved, the numbers of mosquitoes, as well as their length of life, will be reduced. When this happens, all members of the community are protected, regardless of whether or not they are using a bed net. To achieve such effects, more than half of the people in a community must use an (insecticide-treated net).”
According to the Centers for Disease Control and Prevention, with recent outbreaks in the Caribbean and the Pacific, the number of chikungunya cases among travelers visiting or returning to the United States from affected areas will likely increase. Cases have occurred in Africa, southern Europe, Southeast Asia, and islands in the Indian and Pacific Oceans.
“Health professionals should have their eyes and ears more open to cases of sudden, rapid fever and joint pain and where the patient has been recently,” Kucknoor said.
Kucknoor is also director of the Texas General Land Office Beach Watch program for Jefferson County.
Visit www.cdc.gov/chikungunya for more information.