You’re in the Third World here. There are millions of varieties of parasites and bacteria that can perform hideous acrobatics in your intestines. Don’t read any medical textbooks before you come or you’ll never set foot in the country. Happily, though, if you take care and avoid street food you’ll be fine.
Women traveling alone should be careful as always in a Muslim country with all the frustrated young men.
However, young men must also be on their guard. Male rape is not especially rare in Pakistan. There is an old Pathan song that goes:
“There is a boy across the river with a bottom like a peach, but alas, I cannot swim!”
The tribal areas near the Afghani border are wild as hell. One traveller reported that as he visited one village there the men formed an avenue on either side of him and fired guns above his head. He passed without flinching too much and, having prove this manhood, he was then invited to also fire a Kalashnikov into the air.
There’s a good deal of banditry in the outback of the Sind. Ask local advice before travelling there.