A prescription sleep-aid for sleeping at the right times will be great help in adjusting - particularly if you have to sleep on the plane on either or both of your long flights.
I did a trip to Tanzania in 1995 as a single w/ room share to avoid the single supplement and it turned out to be the best trip of my life.
At least back then, it was prudent to take all the over-the-counter meds you might need (Immodium, Tylenol, Benadryl), some antibiotics, and as suggested, a high-tech anti-malarial. Anything you don't use you can leave with the travel company on the last day - they can donate it to the appropriate parties.
A suggestion back then was to bring along some common western goodies for gifts/tips for your guides - digital watches, solar calculators, that kind of thing. I don't know if this suggestion still applies today. The travel company should be able to provide tips on this.
I can provide a lot of photography advice if you let me/us know the extent of your camera experience and what you want to achieve on the trip.