Detection of Chikungunya virus adds to local public health concerns

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A dangerous virus known as Chikungunya has been detected in Harris County, adding to concerns about the public health risks posed by an array of infectious tropical diseases.

Harris County health officials said a mosquito caught in a surveillance trap in northwest Harris County tested positive for Chikungunya virus, which is not lethal but sickens 90 percent of people bitten. This is likely the first local transmission in Texas.

The virus causes fever and joint pain so severe that the sufferer typically becomes immobile.

"This is huge and very concerning," said Kristy Murray, a tropical medicine specialist at Baylor College of Medicine and Texas Children's Hospital. "We don't know the exact risk yet for people, but finding it in a mosquito means people here can get infected in their back yard. It's not confined to people returning from the Caribbean."

Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor, said the area is "in for a long summer" because of Chikungunya, a recent increase in West Nile cases and the possibility of dengue fever coming to Houston.

Nine human cases of West Nile, which can be lethal, have been confirmed this year in Harris County. Murray has published data suggesting that dengue fever, which causes fever, headaches, muscle and joint pains and a skin rash, reappeared in Houston about 10 years ago after an absence of almost 50 years.

"We need greater emphasis on public health preparedness for these neglected tropical diseases," said Hotez. "Instead, the federal government is focused on imaginary threats, like smallpox, anthrax and Ebola, that aren't going to gain a foothold in the U.S."

2 cases found in county

The Chikungunya virus has been confirmed in 10 people in Texas, including two in Harris County, but all of those became infected while traveling overseas. Florida and Puerto Rico are the only American locations where locally acquired human cases of the virus had been reported.

Murray said the area where the mosquito was found - the 77041 ZIP code, an area south of U.S. 290 near Jersey Village - suggests the insect probably picked up the virus feeding on an already infected person, as opposed to traveling to the United States trapped in cargo. She said if the latter were the case, the mosquito likely would be found closer to the Port of Houston or an airport since the species doesn't fly long distances.

Mustapha Debboun, Harris County Public Health and Environmental Services' director of mosquito control, said no one can know for sure where the virus was acquired. He noted the mosquito was collected some 10 to 15 miles from the residences of the previously infected Harris County residents.

The mosquito tested positive for Chikungunya Wednesday, but was collected about a week ago, Debboun said.

Murray said the detection of one infected mosquito suggests the presence of more.

"I doubt the county's detection efforts were so lucky as to find the one mosquito that came in through cargo," Murray said.

Remove standing water

Debboun said the county plans no special strategy to combat the spread of Chikungunya in mosquitoes other than educational efforts. For example, people will be advised to remove standing water in containers and to cover their skin outdoors.

If significant numbers of Chikungunya-infected mosquitoes are found, Debboun said, county staffers could use hand-held foggers in those areas.

Aerial spraying began Thursday night in northeast and northwest Harris County, but its focus is Culex mosquitoes, which bite in the evening and cause West Nile disease. Chikungunya is carried by aedes aegypti and aedes albopictus mosquitoes, which bite during the day. Debboun said spraying for them would be an overreaction.

Murray expressed concern that some cases may be going undetected because people are not seeing their doctor when symptoms occur or, if they do, because the doctors may not recognize the symptoms and order a Chikungunya test. Texas Children's Hospital is routinely testing patients who show up with fever, but hasn't found any cases.

Houston is considered a logical hot spot for Chikungunya because it has an abundance of the two types of mosquitoes that spread the virus. The area also has a subtropical climate and areas of extreme poverty and environmental degradation. In such neighborhoods, conditions such as dilapidated housing, standing water and poor street drainage help the virus thrive.

The joint pain caused by Chikungunya can be excruciating, but most people feel better in a week to 10 days. Still, Murray said, some patients can have joint pain that lasts months or even years. Other symptoms include fever, muscle pain, headache, nausea, fatigue and rash, usually on the trunk or limbs.

There is no treatment for Chikungunya beyond non-steroidal anti-inflammatory drugs, such as acetaminophen and naproxen.