Friday, May 1, 2015



Note: Mostly of local concern or interest.

Experts discuss dengue fever fears amid mosquito discoveries
Posted: Tuesday, April 28, 2015 7:23 pm | Updated: 7:24 pm, Tue Apr 28, 2015.
By Blake Herzog, @BlakeHerzog

About 60 pest and disease control experts from around the state met at the Yuma County Main Library Tuesday for a workshop covering numerous vector control topics, but paying particular attention to aedes aegypti, the species of mosquito which carries dengue fever from human to human.
"This is a human mosquito, it enjoys being around humans, it does well among humans. It's just as happy breeding indoors as outdoors," said Richard Cuming, a vector control specialist with the Yuma County Public Health Services District.

This species was only rediscovered in Yuma County last year after being absent since the 1950s, but its presence in Maricopa County has been growing sine it was first detected in 2001, and dengue itself is spreading throughout the Mexican state of Sonora, across the border from the county.

Joey Martinez, a Yuma County vector control specialist with the environmental health division, said Tuesday officials have been finding the aedes aegypti insect in traps located in the San Luis, Ariz., area, but have not been compiling the numbers yet.

Seventy-one cases of dengue fever, none of which were acquired within Yuma County, were reported here in 2014, Cuming said.

More than 4,000 cases were reported in Sonora throughout 2014, but the disease is mostly found in tropical areas of the world, so its appearance in the desert city of San Luis Rio Colorado, Son., was considered unusual. One dengue-related death was reported in November from that city, among about 60 cases total during 2014.

No cases of dengue fever or a similar virus, chikungunya, which is spread by the same species have been reported so far this year in the county, Cuming said. The season for West Nile virus monitoring has not begun yet, he added.

The health department's planned dengue fever education efforts this year includes flyers handed out door-to-door at homes located near mosquito traps where aedes aegypti is found, he said.
Cuming said this disease differs from the more familiar West Nile virus because mosquitoes transmit it directly between people, instead of picking it up from birds and then spreading it to humans through their bites.

This changes the precautions people must take if they are infected with dengue, as well as what residents should do in order to keep these mosquitoes from breeding on their property.
Patients with dengue fever are advised to avoid getting bitten by mosquitoes at all costs, as well as family members or others in the household, Kirk Smith, supervisor of the Maricopa County Vector Control Division, told attendees at the conference. Aedes aegypti bugs usually bite people on their ankles or calves, he said.
And because aedus aegypti can thrive indoors, people need to pay attention to standing bodies of water inside their homes, emptying and washing pet water dishes, flower vases, bottles, buckets and other containers inside at least once a week.

People should also follow guidelines already used for stopping the spread of the culex mosquitoes which spread West Nile, such as throwing away or turning over anything outside which can collect water including trash cans, tires, flower pots and buckets. Over-watered lawns, irrigation buckets and drywells need to be watched as well.

The dengue fever virus causes no symptoms in many people and flulike symptoms including joint pain and fever in others, but in rare cases leads to dengue hemorrhagic fever, which can be fatal if proper treatment is not received in time.
Warning signs for complications from dengue usually develop three to seven days into the illness and include drop in temperature, severe abdominal pain or vomiting, red spots or patches on skin, bleeding from nose or gums, and blood in vomit or stools.

Professionals from vector control agencies in about half the counties in Arizona were at the conference, including most from the southern half of the state, to compare notes on the spread of the aedes aegypti and efforts to combat it.

Kacey Ernst, an assistant professor of epidemiology and biostatistics at the University of Arizona, spoke about research on the species being done on both sides of the border about the spread of dengue and people's response to the threat.

She said transmission of the disease has been rare in the upper reaches of Sonora, with a handful of local cases reported last year in the Mexican city of Nogales. "Barring last year where we did have a couple of cases, there's generally no local transmission north of Hermosillo," which is about 250 miles south of Tucson, she said.

Likely as a result of the prevalence, Mexican residents studied are more likely to be taking precautions to avoid being bitten or allowing the mosquitoes to breed, she said.

"While repellent is recorded slightly less in Hermosillo than in Tucson, overwhelmingly for all of the other strategies people are reporting doing them more consistently in Hermosillo, so draining stagnant water, clearing the yard of rubbish or containers that might be exploited by aedes aegypti, spraying insecticide, staying indoors, fixing screens," she said.

Despite the amount of research that's been done on this species, experts in Arizona have much to learn about the species spreading dengue, especially how to track it, Smith of Maricopa County said.
"The fact we're picking up huge numbers of aedus aegypti in a trap which was never designed for that species is quite worrisome for us," he said, saying up to 500 males have been found in a trap at a time.