Tag Archives: Miami Mosquito Control

2012 second-worst year ever for West Nile virus

2012 second-worst year ever for West Nile virus

by Elizabeth Weise

8:34PM EDT October 17. 2012 – West Nile virus cases in the U.S. hit 4,531 as of Tuesday, including 183 deaths, making 2012 the second-worst year ever for the mosquito-borne illness, the Centers for Disease Control and Prevention reported Wednesday.

Cases were up 8% from last week, to 282, including 15 more deaths reported, said Erin Staples, a West Nile expert for the CDC. The numbers don’t represent a new wave of mosquito activity, but rather cases slowly working their way through to the CDC, she said. “It’s a reporting lag. We’re not hearing from our state partners that they’re getting a deluge of cases.”

It can take several weeks from when a person feels ill, goes to the doctor and then is tested for West Nile virus. Next, the report must go to the local health department and then to the state health department, which reports it to the CDC. The CDC then updates its numbers weekly, on Wednesdays. “So what we’re seeing is probably illnesses that occurred in September,” Staples said.

The peak of the disease appears to have hit at the end of August, when cases were going up as much as 35% a week. “As the cold weather sets in, particularly in the North and then moving south, that will stop the mosquito activity and then decrease the number of cases,” Staples said.

The state that has been most affected is Texas with 1,580 cases, of whom 55 died. California is next with 285 cases and 11 deaths.

So far, 2012 has surpassed all years but 2003 for the number of cases. In the past week, it surpassed 2006 and it beat out 2002 the week before, Staples said.

Most people infected with West Nile virus will not have any signs of illness, but 20% will experience mild symptoms such as fever, headache, body aches and, in some cases, a skin rash on the trunk of the body and swollen lymph glands.

People older than 50 and those with compromised immune systems are most at risk. About one in 150 people will get more severe symptoms: headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness and paralysis.

Mosquito Bred to Fight Dengue Fever Shows Promise in Study

Mosquito Bred to Fight Dengue Fever Shows Promise in Study

By Reg Gale

Oct. 31 (Bloomberg) — Scientists, attempting to halt Dengue fever, for the first time released mosquitoes into the wild that had been genetically modified to pass on deadly DNA that kills their offspring.

About 19,000 lab-altered

insects were released into 25 acres on Grand Cayman Island in 2009, according to a study, published yesterday in the journal Nature Biotechnology. Later tests showed they made up about 16 percent of the mosquito population and that the fatal gene was carried by about 10 percent of larvae. Scientists estimated the modified insects — all males — were about half as successful in mating as normal.

There are as many as 100 million cases of Dengue reported each year worldwide, making it one of the most medically significant viruses carried by mosquitoes, the report said. There’s no vaccine, boosting the need to limit the insects that carry it, the researchers said. The experiment, by scientists from closely held Oxitec Ltd., a biotechnology company based in Oxford, England, has spurred concern that there may be unintended environmental consequences.

“These data also allow us tentatively to estimate how many mosquitoes might need to be released in this area to suppress the target population,” the researchers said.

The use of genetically enhanced mosquitoes was discussed in a series of articles in the magazine Scientific American this month. In those articles, Helen Wallace, the director of GeneWatch UK, said she was concerned that the new form of insect would become part of a complex system involving predators and prey that scientists have no control over.

2010 Report

She cited a 2010 report by the European Food Safety Authority that raised the potential for illnesses to evolve into more dangerous forms and for other insects to move into the ecological niche created by the absence of mosquitoes.

In the report, the scientists said the percentage of successful couplings by the altered mosquitoes may have been limited because they didn’t fit easily into the insect social system, the physical effects of handling and distributing them or negative effects of the genetic changes on their performance.

Dengue fever, most common in the tropics, causes high fever, headache and rash, along with severe joint and muscle pain.

Oxitec developed the technology, which the Mosquito Research and Control Unit, backed by the Cayman Islands government, implemented for the study, Oxitec Chief Executive Officer Hadyn Parry said in an interview.

–With assistance from Makiko Kitamura in London. Editors: Chris Staiti, Bruce Rule

To contact the reporter on this story: Reg Gale at rgale5@bloomberg.net.

To contact the editor responsible for this story: Reg Gale at rgale5@bloomberg.net.