While travelling in Brazil we took anti-malarial drugs, specifically a fairly new drug combination called Malarone (containing the specific drugs atovaquone and proguanil). I feel compelled to write this note to address misinformation we received repeatedly regarding this serious disease. There seems to be wide-spread misunderstanding and misinformation about malaria in the Amazonas region, it as far as we could tell it extends even to people who should know better including medical practitioners and tour guides!
Our guide specifically gave us a long speech about how dumb our doctor was. He repeated this speech almost verbatim in French and Italian.
Specifically, there is very solid scientific evidence that Malarone can prevent or cure malaria (although it may depend on the place in the world you visit and/or your health, so see your own doctor). This is based on published scientific studies, including some that were conducted in South America. This is notable because I developed food poisoning and was seen by a doctor and nurse while in Manaus, in the Amazonas region. We were informed by both our guide in the Amazon, as well as by the doctor, that there does not exist a preventative mediation and that we were wasting our time taking anything! This is just plain wrong. It's not just a matter of personal opinion since a simple search on google can find you lots of credible objective peer-reviewed scientific data. For people who live in Brazil permanently, the situation is more complex, but for tourists the story is pretty simple: a preventative drug works and taking it is a really good idea.
Note that there are four types of malaria parasite: malaria falciparum, vivax, malariae, and ovale. The first, falciparum, is the most dangereous. All forms are transmitted by the bite of a specific species of mosquito, the Anopheles.
We had no problems with Malarone and the common side-effects are pretty minor (especially as compared to some prior drugs that were in use just a few years ago).
Brazilian J Infect Diseases, Atovaquone and Proguanil Hydrochloride Compared With ...
WebMD Malarone for malaria