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Tag Archive for: disease malaria

India begins outdoor caged trials of genetically modified mosquitoes

India begins outdoor caged trials of genetically modified mosquitoes

India launched a project aimed at suppressing the local Aedes aegypti mosquito population by introducing genetically modified mosquitoes, according to two companies involved in the plan.

A similar project was approved last year in Florida on the heels of the Zika virus outbreak, which has been driven primarily by A. aegypti mosquitoes. Both projects involve so-called self-limiting male mosquitoes — brand name Friendly (Oxitec) — that are genetically modified to produce offspring that do not survive to maturity.

Five open field trials of the mosquitoes in Brazil, Panama and the Cayman Islands each led to a more than 90% reduction of the wild A. aegypti populations, according to a news release from the British company Oxitec and Gangabishan Bhikulal Investment and Trading Limited (GBIT), an Indian company. Open field trials are also planned for India, pending regulatory approval, the companies said.

For now, the India project was launched on Jan. 23 with outdoor caged trials in Dawalwadi. In these trials, the genetically modified mosquitoes are released into cages to mate with wild-type A. aegypti mosquitoes, Matthew Warren, spokesman for Oxitec, explained to Infectious Disease News. The results are then compared with cages where the mosquitoes were not released, Warren said.

In November, officials in Florida authorized a plan to use Oxitec’s modified mosquitoes in a field trial in Monroe County. The decision by the Florida Keys Mosquito Control District (FKMCD) came after residents, apparently reluctant about the method at first, voted to approve the idea.

An earlier survey showed that residents did not support the use of genetically modified mosquitoes as insect control, but the survey was conducted before the Zika outbreak became headline news and prior to an FDA report that said the mosquitoes would have no significant impact on human health, animal health or the environment.

Oxitec is currently deploying the mosquitoes in the Cayman Islands and Piracicaba, Brazil, but Warren said the trial in the Florida Keys is not yet underway.

“We are working with the FKMCD to identify a new site for the trial, and are gathering and submitting additional information to the FDA,” Warren said. “At this stage I don’t have a timeline, but we’re working to ensure that it is held in the most rigorous way possible and launched as promptly as the regulatory process will allow.”

While India is not among the 76 countries that have reported evidence of mosquito-borne Zika virus transmission since 2007, WHO has said that any country with a population of Aedes mosquitoes is at risk for transmission.

The primary aim of the project in India seems to be decreasing cases of dengue and chikungunya, which also can be spread by A. aegypti mosquitoes. According to estimates published in 2014, dengue infects an average of 5.8 million people each year in India at a cost of more than $1.1 billion. The country also has seen outbreaks of chikungunya, including some last year, according to the news release.

“Increasing cases of dengue and chikungunya have been reported in recent years,” Shirish Barwale, member of the board of directors at GBIT, said in the release. “Presently available methods have not been effective against these public health hazards. We are very optimistic that this pioneering technology from Oxitec will help us to control the mosquito responsible for spreading these diseases.” – by Gerard Gallagher

Source: Healio

Behavioral Resistance: Mosquitoes Learn to Avoid Bed Nets

Behavioral Resistance: Mosquitoes Learn to Avoid Bed Nets

Malaria is a notoriously tricky infectious disease. Because of a unique genetic flexibility, it is able to change surface proteins, avoiding the immune response and greatly complicating vaccine development. Furthermore, the parasite is transmitted by mosquitoes, which are difficult to control. Insecticides work, but mosquitoes can develop resistance to them.

One method widely used to control malaria is for governments or charities to provide families with insecticide-treated bed nets. Overall, this strategy is very successful, and it has been credited with preventing some 451 million cases of malaria in the past 15 years. But bed nets are not successful everywhere. In some parts of the world, mosquitoes develop “behavioral resistance”; i.e., they learn to avoid bed nets by biting people earlier in the day.

A team led by Lisa Reimer of the Liverpool School of Tropical Medicine monitored mosquito behavior in villages in Papua New Guinea before (2008) and after (2009-2011) the distribution of bed nets. Data from one of the villages, Mauno, depicts a very noticeable shift in mosquito feeding behavior.

Before bed nets were distributed in 2008, the median biting time for mosquitoes was around midnight. After the distribution, the median time shifted back to 10 pm. Also, a greater proportion of mosquitoes took their dinner even earlier, from 7 to 9 pm.

Worryingly, it’s unclear whether the bed nets were effective at preventing malaria transmission. The number of bites per person per night dropped after the introduction of bed nets, but started to climb in subsequent years as mosquitoes began to adapt. Additionally, the prevalence of malaria infection in humans — arguably, the only statistic that actually matters — dropped in one village, remained the same in a second, and ticked up slightly (albeit insignificantly) in a third.

Despite the mixed results in Papua New Guinea, Dr Reimer believes that bed nets should continue to be used worldwide as part of a mosquito control strategy. However, she notes that behavioral resistance may prove just as vexing as insecticide resistance and, in some locations, may limit the efficacy of bed nets.

Thus, mosquitoes must be monitored for both behavioral and insecticide resistance, as the little creeps stubbornly refuse to die and may be cleverer than we thought.

Source: Edward K. Thomsen et al. “Mosquito behaviour change after distribution of bednets results in decreased protection against malaria exposure.”

Source : Acsh.org

Dengue Claimed 179 Lives, no Death Due to Chikungunya: Government

Dengue Claimed 179 Lives, no Death Due to Chikungunya: Government

Dengue has claimed 179 lives across the country this year while no death has been reported due to chikungunya, though it affected 21,000 people, the Rajya Sabha was told today.

“During 2016 (till November 13), a total number of 179 deaths due to dengue and no death due to chikungunya has been reported in the country.

“The number of positive cases for dengue and chikungunya in the country during 2016 (till November 13) are 90,277 and 21,094 respectively,” Health Minister J P Nadda said in a written reply.

He said the reason behind the steep increase in the number of cases are– water storage practices, poor solid waste management, construction activities, large migratory population, inadequate vector management and lack of protective immunity in the affected population.

Dengue claimed 33 lives in Uttar Pradesh, 28 in West Bengal and 22 in Maharashtra, he said. Replying to another question on the same issue, Minister State for Health Faggan Singh Kulaste said the government has taken measures for prevention and control of dengue and chikungunya in the country, including in Delhi.

He said technical guidelines for prevention and control, clinical management and vector control have been issued to states and UTs while periodic reviews have taken place.

Since January, 2016, 22 review meetings at the levels of Minister, secretary and others were held.

He said since January 12 advisories have been issued at the levels of Secretary (H&FW) and Additional Secretary while states were requested to declare dengue as notifiable disease.

“States were requested to curtail out of pocket expenditure by fixing the rate for testing at Rs 600,” he said.

He said dengue and chikungunya diagnosis is provided through 542 Sentinel Surveillance Hospitals (SSHs) and 15 Apex Referral laboratories (ARLs) identified across the country.

“First version draft of ‘Strategy and Plan of action for Effective Community Participation for Prevention and Control of Dengue’ has been uploaded. A user-friendly App ‘India Fights Dengue’ has been launched while National Dengue Day has been observed on May 16, 2016 throughout the country,” he said.

Source : Smartcooky

UT researchers discover bacterial genes that could lead to effective malaria treatment.

UT researchers discover bacterial genes that could lead to effective malaria treatment.

Researchers at the University of Tennessee, Knoxville, have identified a set of bacterial genes that may help them find ways to lessen the severity of the disease malaria.

Their findings could also aid the research of fellow scientists working in malaria-stricken regions around the world.

The study was published in the journal Frontiers in Microbiology.

Collaborators in this work include Steven Wilhelm, the Kenneth and Blaire Mossman Professor in the UT Department of Microbiology; Shawn Campagna, UT associate professor of chemistry; Gary LeCleir, UT research assistant professor of microbiology; Joshua Stough, UT doctoral student in microbiology; and Nathan Schmidt, assistant professor of microbiology and immunology at the University of Louisville.

The research team earlier this year released a study that found the severity of malaria depends not only on the parasite or the host but also on the microbes in the infected organism. They examined the gut microbiomes of mice.

This new study is helping researchers better understand how gut bacteria work.

Stough analyzed hundreds of genes and eventually found that 32 bacterial genes and 38 mice genes have the characteristics–or phenotypes–that can affect malaria.

“We’re pretty excited because it means there is a limited number of genes to work with,” Wilhelm said. That discovery will make it easier to find a more effective malaria treatment for people.

Much of the study was carried out in Wilhelm’s UT lab.

When the research team released the first study in February, scientists around the world doing similar microbiome work expressed interest.

“The findings in this second study could allow scientists to look at data they’re collecting and try to draw comparisons to see if what we’re seeing is also happening in their samples from malaria-stricken regions,” Wilhelm said. “We’re collecting data in a way that can be used to answer other questions after the fact.”

Hundreds of children die every year from malaria. “If we can find a way to mitigate this disease, we can positively influence a large number of people,” Wilhelm said.

Source: http://www.news-medical.net/

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