BTW if you are going to swim in Lake Malawi or stay in one of the nice lodges in, say, Cape Maclear (e.g. Mgoza Lodge Mgoza Lodge which I recommend) and use the showers, I strongly recommend having a chat to your doctor around 3 months after return about screening (or being treated for regardless) schistosomiasis. A lot of people will tell you it isn't a problem in their local area, by some strange co-incidence, but a colleague of mine in Infectious Diseases has collected a huge series of infected UK travellers returning to Cambridge.