In the developed world, the majority of diseases carried by insects have been mostly or fully eradicated. Perhaps the most prominent example is the plasmodium disease malaria, spread by the female Anopheles mosquito. Though cases in the United States are rare, an estimated 1,500 Americans contract the disease annually, with most being travelers who are returning from overseas.
In the developing world, this is an entirely different story. The National Institute of Allergy and Infectious Disease estimates that a child dies of malaria every 30 seconds and that more than 1 million people die of the disease annually. In total, there are an estimated 300 million cases of malaria annually.
Like any disease, there are certain risk factors that make infection more likely. By being aware of these factors and learning ways to mitigate the risk, you can keep yourself malaria-free, regardless of your travel destination.
In order to contract malaria, you have to visit an area where it is present. Malaria thrives in tropical and subtropical environments and is therefore present on every continent except Europe and Australia. By far, the worst area is equatorial Africa, which accounts for more than 90% of malaria deaths. Southeast Asia and the northern part of South America are also severe malaria locations. If you are travelling to any of these areas, you can assume the first risk factor is present.
Though staying indoors is no guarantee a hungry Anopheles mosquito won't dine on you, outdoor activity greatly increases your exposure. This is especially true from dusk until the sun rises, when the mosquitoes are most active. If you plan to be outdoors at night in a malarial area, make sure you take every precaution to prevent mosquito contact.
Failure to Use Malaria Prophylactics
Though no preventative measure is 100% effective at preventing malaria, modern pharmaceuticals are an excellent preventative measure. If you are planning a trip to a malarial region of the world, and especially if you plan to participate in outdoor activities, you can greatly minimize your chances of contracting the disease by using one of many anti-malarial drugs. Your doctor can determine which drug is best for you and advise you of any risks associated.
Age and Health Status
Though mosquitoes don't discriminate when it comes to who they bite, certain risk factors make it more or less likely that you will contract the disease and how severe the infection will be. By far, children and the elderly make up the vast majority of malaria deaths. Pregnant women are also prone to severe infections and are at risk for complications. The CDC recommends that pregnant women avoid areas where malaria is present. This factor is exacerbated due to the risks involved with pregnancy and prophylactic measures.
Though it is impossible to reduce the chances of infection to zero, knowing the risk factors for malaria and taking steps to minimize them is your best chance of prevention. Malaria is a serious disease, but can usually be prevented with proper planning.