A combined DTaP/IPV vaccine, also called a "4-in-1" vaccine, is a single injection that protects against four diseases: diphtheria, tetanus, acellular pertussis (whooping cough), and polio. 

Tetanus is found worldwide but is generally more common in countries with poor vaccination coverage. Polio is now only endemic in Afghanistan and Pakistan but it can be imported to other countries by infected individuals. Diphtheria can be found worldwide but is more common in developing countries where vaccination coverage is not as widespread.

As you embark on your adventures, it's vital to prioritize safety. Don't forget to visit a travel clinic before your trip to ensure you have all necessary vaccinations and medications. Stay safe on your travels by being prepared and taking necessary precautions. Being proactive about health can make all the difference.