Climate change may limit the spread of dengue fever

Mosquitoes infected with the dengue virus appear to be less able to handle higher temperatures.

Dengue fever is a fatal disease for which there is currently no cure. As the climate warms and mosquitoes advance into new areas, scientists fear the still-tropical disease will spread further. However, it appears that mosquitoes that spread disease cannot thrive in every environment. Because a warming climate may also have a significant impact on infected mosquitoes.

More about dengue fever
Dengue fever is caused by a virus. Dengue virus. This virus can be spread by two types of mosquitoes, namely Aedes aegypti (fever) and Aedes albino (Tiger mosquito). The former is also responsible for the transmission of some other disease-causing viruses, including Zika, chikungunya and – as the name suggests – yellow fever. If you are bitten by a mosquito carrying the dengue virus, the virus can enter your bloodstream, causing you to contract dengue. If you have been infected with the dengue virus, it does not necessarily mean that you also feel ill. The infection often goes without symptoms. If you have symptoms, they often resemble the flu. For example, you have a fever, headache, and muscle and joint aches. The severe form of the disease, dengue hemorrhagic fever, can be fatal.

It is expected that as the climate warms, mosquitoes will spread more around the world. With the help of increased urbanization and climate change, the range of yellow fever mosquitoes, for example, is expected to cross 50 percent of the world’s population by 2050. This leads to a significant increase in the number of people who can be exposed to disease-causing viruses.

Hetty
This means that the yellow fever mosquito, driven by higher temperatures, colonizes new areas. But how well can mosquitoes infected with the dengue virus actually withstand high temperatures? We know that temperature plays a role in the spread of the virus. For example, at lower temperatures, the transmission of the dengue virus is less easy. At higher temperatures, the dengue virus can multiply faster. But what about mosquitoes with the same infection?

study
in a The new study The researchers decided to study the effect of heat on mosquitoes infected with the dengue virus. They did this by placing infected mosquitoes in airtight vials and then immersing them in a water bath heated to 42 degrees Celsius – the realistic maximum temperature a mosquito can encounter in the wild. The researchers then measured how long it took the mosquitoes to become inactive and compared this time to the uninfected mosquitoes.

sensitive
The team found that mosquitoes carrying the dengue virus are significantly more sensitive to heat. Researcher Fallon Ware Gilmore said in an interview with Scientias. nl. In addition, they hibernate three times faster than uninfected mosquitoes. So it means that viral infection can affect the heat tolerance of mosquitoes. In short, infection with the dengue virus makes mosquitoes more sensitive to high temperatures.

Terrain?
You might say that in today’s ever-warming climate, this finding might be a relief. The results suggest that global warming could somewhat limit the spread of dengue fever. However, according to Ware Gilmore, this is not entirely the case. “The risk of dengue can actually go down in areas that get too hot for mosquitoes,” she says. But the risk in previously temperate regions is already increasing. The risk also increases in previously unaffected areas. It is true that infected mosquitoes are less able to survive in extremely hot areas. This can help reduce transmission and possibly the number of new cases in warmer, climate-changing regions. However, this is not a relief, but essentially another step in fully understanding all the interacting parameters that may play a role in how mosquitoes respond to temperature and how that, in turn, can affect human health.”

Wolbachia
In addition, mosquitoes appear to carry bacteria Wolbachia They are also more sensitive to heat. For example, experiments have shown that mosquitoes are infected Wolbachia He fell asleep four times faster than uninfected mosquitoes. It’s bad news. This is the method used by the file WolbachiaBacteria used to fight dengue fever. In recent years, scientists have tried to control the nasty disease by infecting yellow fever mosquitoes with bacteria and then releasing those mosquitoes into the wild. Because when mosquitoes carry these bacteria, their ability to transmit disease viruses is greatly reduced. Unfortunately, the current study now shows that the effectiveness of Wolbachia As a biological control agent it is declining due to climate change. “This is unfortunate, but it shouldn’t stop us from using these bacteria as a pesticide,” Ware Gilmore says. “It’s just another hurdle to consider in warmer climates.”

temperature change
It remains to be seen whether the results of this study are robust. “Mosquitoes can adapt to climate change,” Ware Gilmore says. This has also been proven by another research group. I recently reported interesting findings about mosquitoes that can adapt well to rapid changes in temperature. Whether or not this also applies to mosquitoes that carry the dengue virus. “The ways in which mosquitoes interact and adapt to new environments have not yet been fully identified,” Ware Gilmore says. We know that mosquito populations of the same species differ in heat tolerance. However, there are still many gaps to be filled.”

However, our findings show that both dengue virus and Wolbachia Affect the survival of mosquitoes in hot habitats. “The fact that viral infection is able to lower the heat limit of mosquitoes was an interesting finding for us,” Ware Gilmore says. “We did not think that infection with the dengue virus would affect the carrier mosquito.” This gives us an increasingly better picture of potential danger areas and where people need to be more or less concerned about dengue.