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Blog | June 2017

June 28, 2017: Mosquitoes That Can Carry Zika Spreading in Kansas, CDC Says

The two types of mosquitoes that can carry Zika — and other viruses — have been reported in Kansas.

One type of the mosquitoes has been reported for the first time in 38 Kansas counties, according to a new study by researchers from the Centers for Disease Control and Prevention.

Six researchers examined all of the available county-level mosquito surveillance data to follow up on a study they published last year on the range of the Aedes aegypti and Aedes albopictus mosquitoes.

The “yellow fever mosquito,” Aedes aegypti, mainly stayed in the upper northeast corner of the state, including in Wyandotte, Johnson, Douglas and Shawnee counties.

Closer to Wichita, the Aedes albopictus mosquito, also called the “Asian tiger mosquito,” was more common, reported in 38 Kansas counties. It has been found for three or more years in 22 counties, including Kingman, Sedgwick, Butler and Chase. All of the counties bordering Sedgwick had at least one Aedes albopictus reported between 1995 and 2016.

Sedgwick County was initially put on the Aedes aegypti database in error and was later removed.

Joe Conlon, technical adviser for the American Mosquito Control Association, said he was surprised to see the Aedes aegypti in Kansas.

“Aedes aegypti is generally regarded as a coastal mosquito, even though historically it’s been found in the Ohio River Valley,” Conlon said. “I think what this underscores is people need to be apprised of the fact that these mosquitoes and the diseases they transmit are just around the corner and the world is becoming a smaller place.”

Aedes aegypti prefers to feed on humans, making it the most common transmitter of Zika, dengue and chikungunya.

Both types of mosquitoes have been known to carry West Nile virus.

The Aedes albopictus can also transmit dengue fever and chikungunya. However, the mosquito feeds on animals as well as people, making it less likely to spread the various viruses than the Aedes aegypti. Even when an infected mosquito bites a human, it may be less likely to transmit the disease than the Aedes aegypti, Conlon said.

While Aedes albopictus isn’t the mosquito most known for spreading Zika, the Pan American Health Organization did report that 2016 tests found the Zika virus in Aedes albopictus mosquitoes in Mexico.

The CDC researchers emphasized that the presence of the mosquito in a certain county does not mean it’s abundant in that county and that mosquito-borne transmission of Zika has so far been extremely rare in the continental United States.

The 22 cases of Zika reported in Kansas have all been travel-related. The only documented instances of mosquito-borne Zika in the continental U.S. were in Florida and Texas.

Zika is a relatively mild illness except when it occurs during pregnancy, when it can cause the birth defect microcephaly. A study of almost 1,500 pregnant women with Zika in the continental United States found that it caused birth defects in about 5 percent of cases.

“I think what this paper is telling us is how important it is state and local jurisdictions have in place these surveillance networks to detect the presence of these mosquitoes,” CDC spokesman Tom Skinner said.

The best way to keep both the Aedes aegypti and Aedes albopictus from breeding is to empty out any containers holding water, Conlon said. That includes trash cans, dishes under flower pots and birdbaths.

“They don’t breed in ponds, they don’t breed in puddles, they don’t breed in ditches,” Conlon said. “Particularly with Aedes aegypti, they breed in man-made containers filled with water.”

People should also scrape the sides of a dish when they empty the water, making sure to remove any mosquito eggs.

Wear long clothing and use mosquito repellent to avoid being bitten. The Aedes aegypti is attracted to dark clothing, so wearing light-colored clothes also helps, Conlon said.

Of the mosquito-borne illnesses, West Nile virus — most commonly transmitted by the Culex mosquito — is considered much more of a threat in this region. The Kansas Department of Health and Environment is now reporting a high risk of West Nile transmission throughout the state, and the virus is suspected in the death of a Jackson County, Mo., boy last month.

Most people infected with West Nile don’t experience any symptoms, according to the CDC. For about 20 percent of people infected, West Nile can cause a fever, headache, joint pains, vomiting, diarrhea or rash. Fatigue can last weeks or months after recovery.

Three cases of West Nile in a human are being investigated now, while one case was confirmed in Barton County.

Source: The Garden City Telegram

June 23, 2017: Zika May Have a Startlingly High Sexual Transmission Rate

When Zika swept across Latin America in 2015, a couple of alarming developments quickly followed: microcephaly in fetuses and a murky association with Guillain-Barré Syndrome. Despite ongoing research, much about the virus remains a mystery, including many details of how it spreads.

Mosquitoes are the most obvious vector, but as far back as 2011, virologists suspected that Zika might also be transmitted sexually, a hunch that was confirmed last year. Still, researchers had no idea how easily the virus could be passed through sexual contact.

Now, a pilot study offers new insights about this hard-to-research transmission route, which could potentially spread the virus to new areas. In the study, 12 out of 16 monkeys exposed to Zika through sexual routes tested positive for the virus.

It’s been nearly impossible to identify sexually transmitted cases in outbreak regions because they’re masked by mosquito-transmitted cases, which has made the potentially important vector practically invisible. On top of that, 80% of Zika infections are asymptomatic, meaning that people may not even know they have the disease and thus might be excluded from data about infection rates.

“The study provides a starting point to where we can start gauging risk,” said lead author Andrew Haddow of the United States Army Medical Research Institute of Infectious Diseases. To see how transmission rates had been studied in the past, Haddow said his team looked to HIV/AIDS research. As with that research, this initial model will need to be refined to truly understand human risk, he said.

“This is really big news,” said Enbal Shacham, an associate professor of behavioral science and health education at Saint Louis University, who was not involved in the study. Shacham said that because so little is known about how—and how efficiently—Zika is transmitted sexually, any new information is valuable.

The study involved 16 monkeys: eight rhesus and eight cynomolgus macaques. For each group, the researchers exposed four monkeys to Zika by delivering the virus to the vagina and the other four by delivering it to the rectum.

Researchers anesthetized the animals and, using a lubricated feeding tube, administered a single dose of the virus that was comparable to the highest amount reported in human semen. The method was specifically intended to be nontraumatic, avoiding microtears in the tissue. “We wanted to see what happened in an ideal situation,” Haddow said.

Four of the eight monkeys inoculated vaginally became infected (two of each species), while all eight of the individuals inoculated rectally were infected.

“We were pretty surprised by that,” Haddow said, adding that he and his team expected maybe one in four monkeys to become infected.

The new research provides “important proof” that primates can be infected through vaginal and rectal mucous membranes, said Akiko Iwasaki, a professor of immunobiology and molecular, cellular and developmental biology at Yale School of Medicine.

Despite the infections, none of the animals showed symptoms of the disease. Based on the amount and duration of infectious virus in the macaques’ blood, Haddow’s team thinks humans infected through sexual transmission may be capable of infecting mosquitos with the virus.

Haddow and his coauthors conclude that sexual transmission could be a way for the virus to maintain itself in the absence of mosquito transmission, and it might increase the likelihood of Zika spreading into new areas. “The possibility exists that you could have silent transmission, where somebody gets Zika sexually and has no idea,” Haddow said.

Researchers know that animal models have their limitations, though. John Brooks, a medical epidemiologist with the Centers for Disease Control and Protection (CDC), said we should be “very circumspect” when translating data from research animals to what it means for humans. Nonetheless, he pointed out that both groups of monkeys in Haddow’s research showed detectable virus in their blood for about the same amount of time it stays in humans.“To me that’s saying, okay, it’s behaving in this animal model like it’s behaving in humans,” Brooks said.

Still, he’s not worried about Zika spreading through sexual transmission alone. “Despite everyone’s concern that Zika could be spreading quietly through the country through sexual transmission, we’re just not seeing it,” Brooks said. “And people would have begun to recognize that by now.”

In the United States, the CDC knows of about 50 couples among whom sexual transmission of Zika has occurred. Researchers think those cases are the tip of an iceberg, Brooks said, adding, “I don’t know how big that iceberg is.”

Based on rough estimates of the number of travelers arriving in the United States from active Zika regions, the CDC estimates that 200,000 affected men could enter the country per year. Brooks says that’s a lot of opportunity for the virus to transition and to be sustained, but that hasn’t been observed. (While Zika can be transmitted from women to men, that’s far less common than men transmitting it to their partners, and there is only one known case of woman-to-man transmission.)

One reason that Zika outbreaks in the U.S. haven’t been traced to sexual transmission could be that, unlike some sexually transmitted diseases which remain infectious until treated (and even after), Zika clears from the system fairly quickly, Brooks said.

“In Zika, your body mounts a really effective immune response,” he said. Within about a month after infection, 50% of men will no longer have Zika in their semen, he said. After 81 days, that number rises to 95%.

While the dose of virus used in Haddow’s study is comparable to what can be found in human semen, Brooks said, “men don’t stay at that level for very long.” The level of Zika in semen declines “rapidly and steadily,” he added, although researchers don’t know at what point someone is no longer infectious. But, he points out, the known cases of sexual transmission in the United States have shown that people who infect their partners generally do so early in their illness—something researchers can determine by the timing of the second person’s illness.

For men who have traveled to an area with active Zika transmission, the CDC recommends abstaining from sex or using a barrier protection method (like a condom) for six months after leaving the area. For women who have traveled, the recommendation is eight weeks.

Haddow’s latest research builds on the legacy of his grandfather—who was one of the discoverers of Zika—as well as his own groundbreaking work. It was Haddow who pieced together clues that Zika might be sexually transmitted.

Despite the new research, the unknowns surrounding Zika extend far beyond its sexual transmission rate. Iwasaki, who has studied Zika in mice, said it can cause shrinking of testes and reduced sperm count in those animals. “Zika virus may be a silent disease with significant reproductive impact in humans for years to come,” she said.

Brooks said it took about 20 years to get the necessary data about HIV to run current models to assess both per-act risk of HIV transmission through various routes and the impact of prevention strategies on specific kinds of transmission.

Additionally, Haddow says there’s a possibility of a so-called sylvatic cycle of Zika, in which monkeys transmit the virus to each other sexually. In this scenario, animal populations could serve as a reservoir of the virus, keeping it alive without human hosts.

“It’s going to take years to investigate this stuff,” Haddow said.

Source: PBS

Powassan Virus Diagnosed in New England and Great Lakes Region

Lyme disease is the most well-known tick-borne disease, and for good reason. Every year, there are estimated 300,000 cases across the United States. One tick-borne disease is popping up in New England and the Great Lakes region this year that you may not be familiar with: the Powassan Virus.

Still rare, the Powassan virus has been getting more news this year than in the past due to new diagnoses. The virus is transmitted through the bite of an infected tick. Six different species of ticks are known to spread the virus, one being the deer tick which also carries Lyme. Powassan, however, can be transmitted much quicker than Lyme. An infected tick needs only minutes of attachment to infect a human with Powassan. It’s believe to take 24 to 48 hours for a tick to transmit Lyme.

Powassan generally is a mild viral infection, but it can be life-threatening in some people. Symptoms include fever, headache, and vomiting. Patients will not display the bull’s eye rash that is associated with Lyme which can make a diagnosis more difficult. In the worst causes it can cause encephalitis (brain swelling).

The best way to protect yourself from tick-borne diseases is to protect yourselves from tick bites. When hiking or spending time in areas where ticks are known to be active, wear long loose pants and long-sleeved shirts. Apply a tick repellent to the clothes and exposed skin and always check yourself for ticks. If you find one, remove the tick with tweezers and place in a plastic bag in case you need to have the tick tested for Powassan, Lyme or other tick-borne illness.

Mosquito Squad offers tick control treatments for the yard reducing properties’ tick population. It’s done in two stages. The first is through tick tubes. These are placed throughout the yard when nymph ticks are most active (early spring and late fall). Using mice as a carrier for the treatment, ticks are eliminated when they bite a field mouse (this will not harm the mice).

The second step is proactive tick sprays throughout the year. The treatment eliminates mosquitoes and adult ticks on contact and is applied to areas where ticks are known to harbor on residential properties. We suggest a seasonal package for ultimate protection.

If you want to decrease the tick population in your yard, please contact your local Squad.

June 5, 2017: Australian Plant Extract Can Kill Zika Virus: Study

In a breakthrough, scientists have discovered a group of naturally occurring compounds in an Australian native plant that can effectively kill the Zika virus.

Tests confirmed the compounds halted the virus and stopped it from replicating without damage to host mammalian cells, researchers said.

“Our plaque assays found that the extract from this fairly common native plant killed 100 per cent of the Zika infection in cells,” said lead researcher Trudi Collet from Queensland University of Technology (QUT) in Australia.

“It is also exciting because of the implications of this work for other viruses. Zika, Dengue, West Nile, Japanese Encephalitis and Yellow Fever are all from the same family of viruses – flaviviridae,” Collet said.

“From here, we will work to identify the compounds over the next three to six months, synthesise them and then test them against these other viruses too,” said Collet.

According to USA Centres for Disease Control and Prevention (CDC), there was a 20-fold increase in the number of birth defects in women infected with Zika last year, researchers said.

“Zika is becoming more prevalent in developed countries and, once contracted, the virus has been shown to remain in human sperm for six months,” said Mark Baldock, chairman, Health Focus Products Australia (HFPA), which collaborated with QUT for the study.

“This breakthrough brings new hope that we could one day eliminate the virus from people who contract it in the very early stages and remove that prolonged danger and uncertainty,” said Baldock.

“The research is in the early stages, but we are aiming to ultimately synthesise the compounds in question and turn our attention to preclinical testing,” Collet said.

Zika is a virus that is closely related to dengue and is spread by mosquitoes and by human sexual activity.

While most people experience a very mild infection without any complications, recent outbreaks of the Zika virus in the Pacific and the Americas show that it can be passed from a woman to her unborn baby and potentially cause serious birth defects.

Source: Business Standard

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