Climate change could increase Aedes aegypti populations in tropical countries

Prediction should be taken seriously by public health authorities, especially in developing or emerging economy countries in tropical and subtropical regions

Brazils public health well-known number one enemy, the Aedes aegypti, transmitter of several diseases as dengue and zika, may have a new ally in the next few years: climate change, especially if the temperature increase predictions are confirmed. The alert was called by parasitologist Filipe Dantas Torres, PhD in Public Health and researcher at the Aggeu Magalhães Research Center, Pernambuco unit of the Oswaldo Cruz Foundation (Fiocruz-PE).

It is hard to tell where and when climate change will be perceived. Generally speaking, most countries where the A. aegypti is present will witness an increase in the vectors populations in the following years, if climate changes follows the current trend and if adequate prevention and control measures are not put in practice, said the researcher.

One of the main risks is that a temperature increase, according to Dr. Filipe, would reduce the necessary time for a pathogen to develop in its vector – as dengue virus in A. aegypti. This means reducing the time needed for transmission. This could cause an increase not only in certain vector borne diseases in humans, but also animal diseases, as canine heatworm, caused by Dirofilaria immitis, he explains.

Dr. Filipe points this is a real prediction and must be taken seriously by public health authorities, especially in developing or emerging economy countries in tropical and subtropical regions.

Controlling vectors as A. aegypti must be a permanent priority in places where it exists or where it could be introduced. The case (quite recent) of the reintroduction of Aedes albopictus in Italy is a good example of how, even in areas where the vectors are not present, the risk of introduction and establishment is imminent, he points.

The researcher also recalls other issues faced by poor countries. Among them, lack of human resources and public health infrastructure, what worsens the situation, especially, during political and economic crisis. A second problem is the shift in the populations feeding habits, as avoiding still water buildup – a hard-to-solve problem, especially in Brazils Northeast, where some places have long drought periods.

Effectively controlling these diseases does not depend only on the public power, it depends on each one of us. We must take responsability for our acts and build a collective thinking. In this war against the Aedes aegypti, for example, we must unite in favor of the community. As we say, together, we shall succeed. Alone, we are doomed to fail, said Dr. Filipe.

Climate may also affect developed countries

The alert is not valid only for tropical countries: the first world countries could also be severely affected, especially by diseases transmitted by ticks. In a paper about the theme Doctor Filipe highlights there is an imminent risk of disseminating this arthropod even in regions where it is absent, as some countries in northern and Center-East Europe.

In general, according to the researcher, global warming could lead to the emergence of ticks in areas where todays low average annual temperatures and severe winters are limiting factors for these parasites survival.

The increase in the ticks geographical distribution and population density, associated to other factors, coul lead to an increase in diseases as encephalitis transmitted by ticks, Lyme and Rickettsia , as Mediterranean Spotted Fever. Cases of these diseases may rise in areas until now considered risk-free and, in some areas where they are present, but with low incidence rates, we can expect an increase in the number of cases.

The dogs red tick, Rhipicephalus sanguineus is one of the species to be benefited by the changes. It is present in all continents, but prefers tropical and subtropical climate regions. Studies suggest and increase in the annual average temperature by 2 to 3 degrees Celcius could lead to this ticks geographic distribution expansion. Studies have correlated the temperature increase during summer with the increase of human parasitism by Rhipicephalus sanguineus, as well as cases of the mediterranean spotted fever in France, said the parasitologist.…