Gavin finds out about the fight to stop swine flu spreading
Schools in the capital city of Mexico are closed due to an outbreak of a disease called swine flu.
It's thought this version of the flu is being spread from person to person by coughs and sneezes.
Up to 149 people are thought to have died from the disease in Mexico, where people are being told to stay indoors.
But some people with the flu have left Mexico and passed it to people in other countries. Doctors around the world are working together to stop it spreading.
There are known to be a number of cases spread across America, and it's thought some people in New Zealand may have caught the bug too.
However the cases in other countries haven't killed anyone yet, so it may not be as dangerous away from Mexico.
What is swine flu?
Swine flu is a disease found in pigs
Human cases usually occur in those who have contact with pigs
It's rare to be spread person-to-person and such cases are studied closely
Doctors who have studied the bug have found that it's like other types of flu, but has bits mixed into it from the flu bugs that pigs and birds can catch.
Swine is another word for pig. It's unusual for people to catch swine flu and those that do get it normally do so from being around pigs.
This version is worrying people because it's now being passed from person to person without them being near pigs.
It's important to remember that you CAN'T catch the bug from eating meat from pigs, as long as it is cooked properly.
So far there are no cases of it in the UK, but people returning from Mexico are being checked in case they have the disease.