Medical and dental procedures
Invasive surgical and dental procedures pose a risk of exposure to the virus, especially in less developed countries. In developed countries healthcare workers are required to use new or sterilised equipment and observe universal control procedures. This is to safeguard both the patients and themselves. It does not, however, exclude all risks. In many developing countries these precautions may not be observed. If you have ever had a dental or medical procedure performed abroad, you may have been exposed to risk of infection. The risk will be significantly increased in countries that have a high prevalence.
A similar distinction also exists regarding infected doctors carrying out invasive procedures (particularly those where doctors are using sharp instruments but cannot see their own hands). This is not permitted in developed countries. But this only protects against infections in those whose infections are known. Many developing countries may have less stringent regulations.