It was the water. Human feces. I was in the Peace Corps there. Most of the countryside uses latrines and it flows into the water. I had some tested where I lived. Despite the extortion, which "yes!" is super scary and real (!) El Salvador is one of my most favorite countries in the world. It just takes some time. I hated my first year, but now go back frequently. Sorry to hear about your friend. If anybody else wants to go to EV: simply go to El Tunco. You'll be happy you did. It's an international bubble of paradise.