anti-malaria campaign

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

Scientists create mosquitoes resistant to dengue virus

Mosquitoes get infected when they feed on someone who has the disease. Then they pass dengue to healthy people by biting them.

Each year, dengue sickens about 96 million people worldwide. The virus kills more than 20,000 people, mostly children, the researchers said.

“If you can replace a natural population of dengue-transmitting mosquitoes with genetically modified ones that are resistant to virus, you can stop disease transmission. This is a first step toward that goal,” said study leader George Dimopoulos, a professor of molecular microbiology and immunology at Hopkins.

The genetic modifications significantly increased the mosquitoes’ resistance to dengue. But the changes didn’t boost the mosquitoes’ defenses against Zika or chikungunya viruses.

“This finding, although disappointing, teaches us something about the mosquito’s immune system and how it deals with different viruses. It will guide us on how to make mosquitoes resistant to multiple types of viruses,” Dimopoulos said in a Hopkins news release.

He and his team said more research and testing is needed before these dengue-resistant mosquitoes are introduced into the wild, a process they said could take a decade or more.

Forty percent of the world’s population live in areas where they are at risk for dengue infection, the study authors said. The virus is most common in Southeast Asia and the western Pacific islands. But dengue infections have been increasing in Latin America and the Caribbean.

The research was published Jan. 12 in the journal PLOS Neglected Tropical Diseases.

Source: UPI

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 cases grew by 63% in Maharashtra this year

The number of dengue cases in Maharashtra rose 63% between January and October this year compared to the same period last year. The number of deaths have remained the same, with 22 deaths in the comparative periods for 2015 and 2016.

Dengue is transmitted by the aedes aegypti-species of mosquito and has become a major public concern in the past two months, doctors said. A total of 5,653 cases were reported by the state epidemiology department this year as compared to 3,461 cases last year, with cases coming from cities like Mumbai, Kalyan-Dombivli, Pune and Nashik, said Dr Kanchan Jagtap , joint director of health services of the state.

“Every year, there is an increase in the number of dengue cases post monsoon. Moreover, the increase in construction sites have created an ideal environment for mosquito breeding,” she said.

Although the number of dengue cases has gone up, not everyone who is infected with the virus develops complications, said doctors. “Say out of 100 people infected with dengue, only 10 show complications such as a drop in blood pressure, severe drop in n platelet counts, ”said Dr Pradeep Shah, physician, Fortis Hospital, Mulund.

“Most of the patients who show complications are people who have had dengue in the past, young children, elderly and pregnant women. These are the vulnerable groups,” he said.

Doctors also said state data could be giving an incomplete picture of the dengue situation, because only those cases where the patient has tested positive for dengue infection using the ELISA (enzyme-linked immunosorbent assay) method of testing are counted as confirmed. “We treat so many patients who have all symptoms of dengue infection, but their blood test reports for ELISA test are negative. These numbers are not accounted for in the state’s data,” said Dr Altaf Patel, director of medicine Jaslok Hospital.

October 2016

Kalyan-Dombivali Municipal Corporation

Number of cases 63 number of deaths 5

Mira-Bhayander Municipal Corporation

Number of cases 33 number of deaths 2

Brihanmumbai Municipal Corporation

Number of cases 941 number of deaths 2

Source : Hindustantimes.com

How Sri Lanka bit back at mosquitoes and wiped out malaria – podcast

Sixty years ago, Sri Lanka was one of the countries most affected by malaria; in September 2016, the World Health Organisation declared the country free of the disease. Dinitha Rathnayake charts the journey of a huge victory for public health.

Dinitha Rathnayake, a radio journalist based in Colombo, looks back over Sri Lanka’s long struggle with malaria. She speaks to people who lived through the 1980s health crisis as well as the doctors, health workers and officials who helped to eliminate the disease.

Mahieash Johnney, of Sri Lanka’s Red Cross, looks back to the 1930s, when more than 5m cases of malaria were reported in the country.

Dr HDB Herath, the director of Sri Lanka’s Anti-Malaria Campaign, talks about what was involved in tackling the disease, from the use of insecticides to early detection through mobile health clinics.

The AMC’s SR Jayanetti discusses how the unique conditions of different regions affected malaria transmission – and how understanding this was a big part of the battle in containing it.

Finally, looking ahead to the challenge of maintaining Sri Lanka’s malaria-free status, Dr Anula Wijesundere, who saw the epidemic at first hand as a consultant at Polonnaruwa hospital from 1986 to 1989, talks of the danger of complacency and the vital importance of early diagnosis,

Source: theguardian.com