yes an organisation with local offices like doctors without borders for example i think they have offices in the big towns,or worlwide doctors the blue ones related to the united nations , i think it's the same they have probably basic offices for drugs addicts,prostitutes etc... you know the reduction of the risks
it's quite common in big european towns they have buses touring from place to place if you haven't the possibility to have an appointment with a classic doctor in town,it's an alternative,if your country had basic take in care for medical treatments like the base social security of your state for citizens,it's not a big deal but in general a complete stds check up is at minimum two or three weeks,it was like this in the 90's maybe it's have change a bit nowadays
the better go on the website of WHO https://www.who.int