Worldwide with quarantines from customs is virtually impossible. Customs can't stop human or cocaine trafficking from making it into the country, much less und

Worldwide with quarantines from customs is virtually impossible. Customs can't stop human or cocaine trafficking from making it into the country, much less undocumented immigration. All you need is a half dozen sick people who are trying to hide from the authorities, and you're back to square one. Most countries are not islands.