What is the most deadly animal on the planet? No, not snakes or sharks it is the tiny mosquito. According to the World Health Organization, mosquito bites result in the deaths of more than 1 million people every year. The majority of these deaths are due to malaria. There are an estimated 300 and 500 million cases of malaria occur each year and a child dies from malaria every 30 seconds.
Dengue fever and chikungunya are other mosquito borne diseases which can be fatal in severe cases and are increasing rapidly because mosquitoes are becoming resistant to insecticides.
Zika the new health threat, is a virus spread by mosquitoes. It causes only a mild illness and 80% of patients have no symptoms at all but it seems to be associated with disorders of the nervous system, particularly microcephaly in developing foetuses, a condition in which babies are born with small and poorly functioning brains which usually causes mental retardation. Twenty one countries in the Caribbean, North and South America have been affected and women have been advised not get pregnant in some of these. It has spread on a massive scale in the Americas, where transmission was first detected in Brazil in May 2015. Large numbers of the mosquitoes which carry the virus and a lack of any natural immunity in the population is thought to be helping the infection to spread rapidly. It was first discovered over 60 yes ago in Africa but the link between microcephaly and infection was not noticed. This could be because health surveillance is very poor in these countries or because the majority of the population would have an infection in childhood so by the time girls get pregnant they have already developed resistance to the virus.
There have been a handful of Zika cases reported in the U.S., including three in Florida. So far, none were contracted locally. All were recently returned travelers believed to have contracted Zika overseas. But there are concerns that Zika, like dengue and chikungunya, could spread to warm climates in the U.S, like South Florida where there have already been out breaks of dengue.
Genetically modified mosquitoes
Oxitec has manipulated the genes of mosquitoes and bred and released into the wild male mosquitoes so that that they don’t produce viable offspring. When females mate with the GMO males, they lay eggs that hatch but the larvae die before adulthood. Oxitec says trials conducted in Brazil and other countries over the past decade show releasing bioengineered male mosquitoes can reduce the wild Aedes aegypti population by 90 percent. Aedes aegypti is the mosquito species responsible dengue fever, chikungunya, zika fever and yellow fever viruses so this technology may extremely helpful against this new threat. Aedes bites in the day time and lives in very small pools of water such as dustbin bin lids, so normal precautions such as using mosquito nets at night [useful against anopheles the malaria spreading mosquito that bites at night] and spraying lakes and reservoirs are not effective.
The biggest killer however is malaria. The world’s first malaria vaccine was recommended last year. It is hoped that the Mosquiriz jab, developed by GlaxoSmithKline and the Bill and Melinda Gates Foundation, will help prevent some of the half a million malaria deaths every year. The vaccine may provide protection to thousands for as little as $5 each, has been approved by the European Medicines Agency it now needs the approval of health officials in the African region.
The threats from mosquitoes are increasing because of resistance to pesticides and resistance to medication but there is hope and there are possible new solutions. They can’t come soon enough!