News Scan for Aug 10, 2016

Chikungunya in Kenya
H5N2 in French ducks
Mosquito traps to fight malaria

WHO: 1,792 chikungunya cases in Kenya

Yesterday the World Health Organization (WHO) posted a statement on a chikungunya virus outbreak in Kenya that began in May, with partial genetic sequencing suggesting that the strain is linked to one that has circulated in the Indian Ocean islands, Asia, and Europe since 2005.

On May 28 the Kenyan Ministry of Health reported an outbreak of the mosquito-borne disease in the Mandera East sub-country. The Kenya Medical Research Institute (KEMRI) Arboviral Laboratory in Nairobi has confirmed chikungunya in 38 out of 177 samples. As of Jun 30, Kenya had 1,792 suspected cases of the disease, which is being transmitted by the Aedes albopictus mosquito. So far, no deaths have been reported.

The WHO cautioned that this strain of chikungunya could cause a wider outbreak, especially because the Mandera area borders an area of Somalia with few healthcare facilities.

The agency said the chikungunya strain that began spreading in the Indian Ocean islands in 2005 had a mutation that increased its adaptation to one strain of A albopictus, leading to increased transmission to humans, If the preliminary sequencing results for the Kenyan outbreak strain are confirmed, the outbreak could involve "significantly higher attack rate[s] than with the formerly circulating African strain," the statement said.
Aug 10 WHO statement  


H5N2 strikes French duck farm

Surveillance in a region of France hit by several avian influenza outbreaks over the past several months detected another outbreak at a commercial farm that raises ducks for foie gras production. The latest detection involves highly pathogenic H5N2, found on a farm in Aveyron department.

None of the birds showed clinical signs, but the 11,000 ducks at the facility were destroyed to curb the spread of the virus, French agriculture ministry officials said in a report yesterday to the World Organization for Animal Health (OIE).

In July, another farm in Averyron reported an H5N1 outbreak. Outbreaks involving five new strains of European-origin avian flu, three of them highly pathogenic, have been occurring in southwestern France since November 2015. The latest event is the 81st outbreak reported in the area.
Aug 9 OIE report


Study: Odor-baited mosquito traps show promise against malaria

A newly developed solar-powered mosquito trap baited with human odor has the potential to reduce the prevalence of malaria, according to 3-year trial by Dutch and Swiss researchers who tested the system on the Kenyan island of Rusinga. The team published its findings yesterday in The Lancet.

The trap targeted Anopheles funestus mosquitoes, the main drivers of malaria on the island. Over the study period, 4,358 household were equipped with the solar-powered systems, which also provided LED lighting and cell-phone charging.

Researchers measured malaria cases once at baseline and five times throughout the rest of the 2-year rollout period. Unexpectedly low malaria levels during the rollout period kept the team from coming up with a precise effectiveness estimate, but they said the traps were associated with a 70% decline in mosquito populations and that malaria illness was 30% lower in households with traps than in those without them.

They said the results suggest that mass trapping can be used as an insecticide-free way to control mosquitoes and cut disease and that the approach could be useful for battling other viruses, such as dengue or Zika. Though the systems cost more than other interventions, the expense could be reduced over time, such as by using a trap that doesn't require power and developing a bait that doesn't need to be replaced as often, the authors wrote.

In an accompanying Lancet editorial, Gerry Killeen, PhD, of the Ifakara Health Institute in Tanzania and the Liverpool School of Tropical Medicine in the United Kingdom, said the study is the first to show entomological and epidemiologic effects without treating any living malaria host or even using any insecticide.

He wrote that system's shortcomings are its cost and its failure to capture sufficient numbers of other important species, such as Anopheles gambiae and Anopheles arabiensis. However, though more work needs to be done before malaria programs can use odor-baited mosquito traps, Killeen said the authors clearly show that the approach is a viable option.
Aug 9 Lancet abstract
Aug 10 Wageningen University press release
Aug 9 Lancet commentary

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