leech socks take care of the little brown terrestrial leeches just fine (DEET on the boots gives additional help!). The ones you need to take extra care about are the tiger leeches which wait in the bushes and drop onto you from above. They don't have an anaesthetic to go with their bite like the terrestrial leeches do, so they're pretty nasty critters. Best thing is to just keep in mind that they're actually harmless apart for a little blood loss. The mosquitoes, ticks, etc are the real worry.....