The spread of measles continues in the United States and now more than 1,000 people are being watched for it in Arizona. The measles outbreak started in California, and has now put people in the Phoenix area at risk.

Because measles is so highly contagious, the health officials in Arizona are asking the people who have been exposed and have not been vaccinated to take precautions. They have been advised that they need to stay at home for the next 21 days, or wear a mask if going out in public.

Recognizing that it is difficult for most people to stay at home for the full 21 days, State Health Services director Will Humble said that it is important to do so. Going out of the house, he said, is all it takes to infect a large number of people, if you were just to visit a large store.

The exposure that exposed so many took place at a health clinic in Phoenix. It is believed that about 195 people were exposed. A woman had visited the hospital, and it was learned later that she was infected. While at the hospital, she had no visible indications of infection, but is has been confirmed since that she has the measles.

Health officials are hoping that the actual spread of measles may be limited in Phoenix to as few as seven people. So far, they do not know which of the children have been vaccinated and which ones were not. They are in the process of contacting people who have children and who were at the clinic on Jan. 20 or Jan. 21.

The reason for so many people needing to be watched for measles is because infected people are contagious even before there are any visible symptoms. It is one of the most highly contagious diseases known to the human race. Being infected with measles means becoming contagious a full week before any symptoms develop, and remaining contagious for a full week after the symptoms have disappeared.

So far, there are 95 people who have been infected with the measles virus across the nation. 79 of the cases are located in California, but measles has also spread to Colorado, Oregon, Nebraska, Washington, Utah, and Mexico.

Because this measles outbreak started at Disneyland, California’s offices of the Center for Infectious Diseases (CDC), has strongly recommended that children under the age of 12 should avoid going to the park. Others who have not been vaccinated are also advised to stay away from the Anaheim, California park.

Health officials strongly advise getting the measles vaccine if one has not been obtained yet. While the vaccine is the best defense, it is not an absolute guarantee to ward off the infectious virus. A few of those who have become infected have had the vaccine, but the large majority is unvaccinated.

Trying to keep the measles outbreak under control can be very costly, which is why quarantine is very important. It involves the police who have to enforce the quarantines (where it is being enforced), academic institutions of all levels have to watch for infections and may provide some care, contacts have to be traced and then contacted, businesses and even health agencies may have to temporarily close, and so on.

There are several groups of people who are at the highest risk of getting the measles virus. This would help explain why 1,000 people in Arizona are currently being watched for measles. Those most at risk includes those who are less than one year old, seniors, those who have not been vaccinated, and those who received a vaccine with an inactivated vaccine, which was given between 1963 and 1967, and were not re-vaccinated.