August 4, 2016
Researchers have been releasing thousands of mosquitoes into the wild – and for good reason.
Controlling mosquito-borne viruses has proved to be a challenge for medical science, as Zika has made all too clear. However, researchers at China’s largest “mosquito factory,” a 39,000 square foot facility in Guangzhou, are breeding mosquitoes at a rate of some five million a week. The intent is to slowly release the insects into the wild to prevent the spread of diseases like dengue fever and malaria.
These aren’t just normal mosquitoes, however. The all-male specimens have been specially altered while still in development to carry wolbachia. This bacteria has a unique ability to effectively sterilize any of the female mosquitoes that males mosquitoes mate with.
The researchers are releasing thousands of those altered male mosquitoes on a 3 km stretch of ground so that they can observe effects of the wolbachia bacteria and understand its potential to reduce human infection from mosquito-borne illnesses. The idea is to target “hot spots” for infection, cutting local mosquito populations and thereby preventing the spread of diseases like Zika and dengue.
“The aim is trying to suppress the mosquito density below the threshold which can cause disease transmission,” Zhiyong Xi, director of the Sun Yat-sen University Centre of Vector Control for Tropical Diseases, explained. “There are hot spots. This technology can be used at the beginning to target the hot spots. It will dramatically reduce disease transmission.”
Zhiyong estimates that since beginning this initiative in 2015, the mosquito population in residential release areas has dropped by around 90 percent. The second phase of this process will be to release a carefully calculated number of wolbachia-infected females into the local environments. The females will pass on their wolbachia infection to their offspring, ensuring their sterility.
Obviously this kind of population or “vector” control could present issues if not carefully managed, but the researchers believe this approach will be crucial for controlling the mosquito population. Hopefully the efforts will aid in eradicating new cases of dengue fever and other mosquito-borne diseases in those areas.
This isn’t the only initiative to take this approach either. Various programs across the world are using altered mosquitoes to combat infectious diseases.
Infecting mosquitoes and releasing them into the general population is cost-effective and comes with an added bonus: wolbachia infection does not increase the risk of mosquitoes transmitting other pathogens, nor does it pose a risk to human health.
Insecticides are commonly used to prevent mosquito-borne disease, but conservationists and wider environmental groups say this strategy is expensive, hard to deploy and potentially dangerous to other insects and larger animals.
On the surface, the bacterial infection approach appears to side-step impacts on the food chain or wider environment. However, because birds and other animals feed on mosquitoes, a significant population reduction could impact wildlife. This element of disease management must be examined in more detail.
Obviously, with the United States and Brazil facing significant challenges related to Zika virus, this approach won’t work in the short term, but as one of several longterm management strategies, the bacterial infection approach seems to offer a large public health benefit for relatively small investment.
Source: http://www.care2.com/causes/chinas-mosq ... =hootsuite
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