Be Prepared: The Most Dangerous Animals on Our Planet Are Here to Stay

They are the most beautiful mosquito species we have: The Aedes family. Small, dark with bright white spots and stripes. But that is only beauty on the outside. In reality, these Aedes mosquitoes are tiny murder machines: They are the most deadly mosquito family on our planet, as they can transmit a range of viruses. Although chikungunya and, more recently, Zika have been stealing the show, dengue and yellow fever pose a major threat.

The Aedes mosquitoes are tiny murder machines: They are the most deadly mosquito family on our planet, as they can transmit a range of viruses

But what makes the Aedes family so ‘successful’? For one thing, it is less dependent on rain water than it’s cousin Anopheles, responsible for transmitting malaria. Aedes is not very picky, and will breed in the tiniest water collections, such as tin cans, clogged rain gutters, (plates under) flower pots, buckets, drinking bowls for pets, bird baths, etc. In addition, they are aggressive and frequent biters, and could feed upon you every day, whereas Anopheles only bites between laying eggs (every 3 days when it is very warm).

The more recent successes of the tiger mosquito, one of the Aedes family members, in Europe can be attributed to its capability to quickly adapt to local circumstances: It has adapted to our colder winter climates and proved to be a good competitor against local mosquito species. In also manages to invade larger parts of Europe every year by hitchhiking, using car and trucks (passive transport).

Although chikungunya and, more recently, Zika have been stealing the show, dengue and yellow fever are far more devastating and leave behind death and destruction

Viruses also deserve some credit: Unlike the malaria parasite that requires a minimum of 8-9 days to replicate within the mosquito before onward transmission, viruses are observed to go through the mosquito much faster, and sometimes infect a new person within 1-2 days. This developmental speed depends in part on temperature, which highlights another difference: Where the growth of malaria parasites slows down after a certain optimum temperature, viruses replicate faster and faster when temperatures increase, making them not only dangerous now but also in the future if temperatures keep on increasing.

What makes the Aedes family so ‘successful’? For one thing, it is less dependent on rain water than it’s cousin Anopheles

What to do to prevent those pesky mosquitoes from biting you, and thus transmitting diseases? You could wear long-sleeved shirts and long pants, socks, shoes, and a hat during the afternoon and early evening (although I am sorry to say that mosquitoes manage to bite through certain fabrics), use a repellent (with DEET) and sleep under a bednet when mosquitoes are still active when you go to bed. But the most obvious way is to eliminate all sources of standing water on your property so mosquitoes cannot multiply. But that requires a collective effort: You will still be bitten by mosquitoes if your neighbors are not taking any action.

At ISGlobal we have a particular interest in the tiger mosquito, as this species is abundant in Catalonia (as well as in the rest of Spain) and we assume it can transmit the full range of viruses mentioned before. But we are also careful not to only focus on the tiger mosquito. Our climate is suitable for the Aedes aegypti, or the ‘yellow fever mosquito’, which inhabited in Spain up to 1953.

In addition, other invasive Aedes mosquitoes (Ae. koreicus and Ae. japonicas) have been reported in Europe and may find their way into Spain. But to keep a close eye on the current mosquito situation, to evaluate disease risk and to be prepared for outbreaks, a proper entomological surveillance system is needed. And there lies the crux of the matter: The current lack of surveillance in many parts of the world is very worrying. Looking at warmer countries like Spain, surveillance is of the utmost importance, as it is not a question of ‘if’ but of ‘when’ our Aedes mosquitoes will transmit diseases.