For a tiny little bug, the mosquito is attracting a great deal of attention from scientists around the world. For many in the developed world, the insect is known as a persistent and pesky nuisance. But for those living in more tropical climates, the mosquito is a carrier, or vector, of some of the world’s deadliest diseases.
As temperatures creep up around the globe, the active mosquito season lengthens and environments that were once inhospitable to tropical mosquitos become breeding hotbeds. People in the UK face a potential upsurge in mosquito and tick-borne illnesses as a result of climate change, according to a new report published in The Lancet.
Climate Change and Vector-Borne Illnesses
The report reviews the risks posed by vector-borne diseases in the UK both now and in the future. By examining the anticipated effects of climate change on habitat and mosquito populations, Dr. Jolyon Medlock and Professor Steve Leach, from the Emergency Response Department at Public Health England, model some of the vector-related public health risks associated with climate change.
A vector is an animal or insect capable of transmitting disease to humans. For example, certain mosquito species transmit malaria, and ticks are capable of transmitting Lyme disease.
According to the Lancet review, higher summer temperatures promote mosquito development and increase the geographical regions capable of sustaining active, disease carrying mosquito species. Specifically, the Asian tiger mosquito, or aedes albopictus, is increasingly abundant and capable of transmitting Dengue fever and the Chikungunya virus.
Professor Leach discusses the need for prevention and disaster planning in the press release:
We are not suggesting that climate change is the only or the main factor driving the increase in vector-borne diseases in the UK and Europe, but that it is one of many factors including socioeconomic development, urbanization, widespread land-use change, migration, and globalization that should be considered. Lessons from the outbreaks of West Nile virus in North America and Chikungunya in the Caribbean emphasize the need to assess future vector-borne disease risks and prepare contingencies for future outbreaks.
Climate change models predict suitable temperatures for 1 month of Chikungunya virus transmission in London by 2041, and up to 3 months in southeast England by 2071, according to the press release. However, there are ways to plan for – and possibly prevent – the spread of these deadly illnesses.
Given the ongoing spread of invasive mosquitoes across Europe, with accompanying outbreaks of Dengue and Chikungunya virus, Public Health England has been conducting surveillance at seaports, airports, and some motorway service stations. Although no non-native invasive mosquitoes have been detected in the UK so far, a better system to monitor imported used tires, in which disease-carrying mosquitoes lay their eggs, needs planning,
says Dr. Medlock.
Something’s Got to Give
Tropical, vector-borne diseases are cropping up across Europe. According to an article in The Independent, there have been 200 cases of Chikungunya in Italy, 700 cases of West Nile virus in Italy, Serbia, Romania, and Hungary, and 1,000 cases of Lyme disease in the UK. Additionally, Dengue fever has reached France and Croatia, and malaria has been re-established in Greece.
The European maps (courtesy of VectorNet) below indicate the regions with active populations of aedes albopictus and aedes aegypti.
We’ve all heard of the ice melts and rising sea levels associated with climate change. Many of us may not have considered the ripple effects, including increasing populations and habitats of disease-carrying insects, of global warming.
Clearly, something has to give.
Enter the Innovators
While fogging and insecticide-laced mosquito nets may help curb mosquito populations, additional innovation is needed to prevent significant public health crises in Europe and North America.
If you really want to suppress the [mosquito] populations, you either need a technology like [genetic modification] or you're going to be spraying...a lot of pesticides, which we know is not a solution,
Murray Isman, an entomologist at the University of British Columbia, told National Post.
Oxitech, a British biotechnology company, is using advanced genetics to develop a potentially more effective method of controlling vector population growth. Its solution is based on the use of the Sterile Insect Technique (SIT), and involves the introduction of genetically modified, sterile male mosquitos into natural habitats. When these adult males are released, their offspring inherit the self-limiting genetic trait and will die before reaching adulthood, thus reducing population growth.
The National Post article contends that Oxitec has released millions of genetically modified mosquitoes in Malaysia, the Cayman Islands, Brazil and Panama, where the aedes aegypti populations decreased by more than 90%. Critics of genetic modification contend that there is little independent evidence of the efficacy of this method, which may carry risks to humans such as increased antibiotic resistance and allergic reactions.