I use DAN which is a diver insurance program but includes general travel as well. Covers air evacuation which is not that unusual in remote areas and costs $20k or more. What I like is that the 800# is manned by people knowledgeable about tropical diseases. Common problem with travelers getting treated for malaria in many areas is that there can be more than one type and the treatments vary with some being completely ineffective if diagnosis is incorrect.
I would also plan on treating all my garments with permethrin (cheap to buy in 13.3 or 36.8 percent solution and dilute) which is great for repelling mosquitoes, chiggers, ticks, fleas, and this is important in Africa (or many parts of the US) with regard to Dengue fever, malaria, and other diseases transmitted through these carriers. US troops in Afghanistan and Iraq are issued field kits with permethrin to treat their clothes (lasts for up to 50 washings) to prevent malaria from mosquitoes as well as problems from camel spiders, sand fleas which carry Leishmaniasis, a type of skin disease.
Side benefit is that you can avoid using DEET and the problems it can cause for plastics and use a much reduced amount of 20% Picaridin solution and Avon Skinsosoft only on the exposed areas. Permethrin also greatly increases the effectiveness of mosquito netting.
The best insurance is prevention.