Eli5: Why is there no malaria in Italy despite having so many mosquitos


I’m in Italy currently and did not need to take any malaria tablets to come here. However I’m being assaulted by mosquitoes since coming here and after Googling I found malaria was eradicated in the 1960’s but can’t find out how exactly

In: 10

The fight against malaria in Italy has been a long and strenuous one. Explained in a few words, It got better after Italy started implementing the use of DDT (a chemical) to get rid of Mosquitos around all of Italy and they eventually made it. But it took a lot of time and effort until they made it, the history about it is pretty interesting but I didn’t search for an English source (I got the Italian one).

The short version: From the 1930s to the 1050s, a lot of DDT was sprayed, a lot of other insecticides, and a lot of swampland was cleared out.

Here’s a link from the NIH that tells you the same thing, but with big words and more detail.
There are still several hundred cases of malaria a year in Italy but they’re all imported.

To add to the other answers, you may ask “why hasn’t it come back, after all, the mosquitoes came back after being killed by DDT”

The thing is, malaria has a multi-stage life cycle…a mosquito has to bite someone with malaria, then malaria has to propagate in the mosquito, then it has to bite someone else before it dies.

In a country like Italy, where doctors screen people for malaria and treat them, this chain of transmission is difficult to maintain, because most people with malaria are going to be getting treatment (which reduces the number of malarial parasites) and also won’t be out and about getting bitten by mosquitoes as much. But antimalarial treatments are much more effective at reducing transmission in countries where malaria is rare than in countries where it is common, so treatment alone doesn’t eliminate malaria in countries where it is widespread.

Malaria is a parasite that mosquitos transmit but it requires human hosts. If none of the humans in an area have malaria then mosquitos will not transmit it because they will not be infected with it.

So malaria eradication campaigns generally work/worked by reducing mosquito populations temporarily (killing infected mosquitos with pesticides) while diagnosing and curing people with malaria. The mosquito population comes back but they no longer carry malaria. Italy, like the US and other developed countries had large eradication campaigns that eliminated malaria from the region. Then health departments monitor and treat cases to prevent it from returning.

Not all mosquitos are able to transmit malaria and some are more adapted to transmit the disease. The most successful vectors of malaria are from the anopheles gambiae complex, with the anopheles gambiae itself begin the primary vector of malaria.
Malaria is caused by a single-cell organism called plasmodium, and some of the plasmodium strains are so adapted to anopheles mosquitos that they are able to reproduce better in the mosquito salivary glands and the plasmodium managed to escape the anopheles immune system throughout evolution.
Anopheles mosquitos that transmit malaria are supposedly eradicated in developed countries like italy, but some developing areas, mostly africa in which the anopheles gambiae is present are still suffering from malaria due to gambiae begin so potent in transmitting the disease.