Measles in Puerto Rico: symptoms, contagion and what to do

Measles is a virus that lives in the mucus of the nose and throat. It spreads through coughing and sneezing, and by breathing the air in a room where a sick person has been: according to the CDC, the virus can stay in the air for up to 2 hours after that person leaves. It spreads only from person to person.

It is one of the most contagious infections there is. The CDC estimates that if you have measles, up to 90% of the people close to you who are not immune will also get infected. And you can spread it before you know you have it: from 4 days before through 4 days after the rash appears.

According to the CDC, measles symptoms usually start 7 to 14 days after contact with the virus, and the rash appears on average about 14 days after exposure (range 7 to 21 days). Symptoms come in this order:

Measles is much more than a rash. The CDC says it causes ear infections in about 1 in 10 children and diarrhea in fewer than 1 in 10 people. Serious complications include pneumonia, the most common cause of measles death in young children, and encephalitis (brain swelling), which can lead to seizures, deafness or intellectual disability.

In the United States, about 1 in 5 unvaccinated people with measles is hospitalized, and 1 to 3 of every 1,000 infected children die. The people at highest risk are children under 5, adults over 20, pregnant people and people with weakened immune systems. In pregnancy, measles can cause early birth or low birth weight.

Don’t walk into a doctor’s office, urgent care center or ER without calling first. The CDC asks you to call ahead so the facility can prepare and no one else is exposed in the waiting room. In the meantime, stay home and away from other people.

A video doctor visit lets you see the doctor without leaving home or exposing anyone. You see Dr. Diana Nieves Castro, a general practice physician licensed in Puerto Rico with several years of emergency-department experience. She evaluates your symptoms, your vaccines and who you were in contact with, tells you what to watch for and, if you need an in-person test, guides you on where to go and how to get there without exposing others. If appropriate, the doctor prescribes and we send your prescription to your pharmacy.

There is no specific treatment for the measles virus: according to the WHO, care relieves symptoms and prevents complications, and two doses of vitamin A are recommended for children under 5 with suspected measles. The doctor decides with you what is right for you. The CDC says to stay home until the fifth day after the rash appeared.

We see adults and children of all ages. For patients under 21, a parent or legal guardian stays on camera for the whole visit and shows photo ID. You need to be physically in Puerto Rico during the visit, and visitors are welcome.

Video doctor visits 24/7 — book online and choose your time right away.

A measles titer is a blood test that looks for measles IgG antibodies. The CDC accepts laboratory evidence of immunity as proof that you are protected. It helps when you can’t find your vaccine record, or when school or work asks you to prove immunity. It is a test for people without symptoms: if you were exposed and are not protected, from day 5 to day 21 after the exposure call the lab or your doctor before going in.

The doctor can give you a lab order for the titer and goes over the result with you. An equivocal result counts as negative, per the CDC. If you have no written vaccine record, the CDC says you can simply get vaccinated: the MMR vaccine is safe.

According to the CDC, acceptable evidence of protection is: written documentation of the MMR doses recommended for you, a lab test showing immunity, lab-confirmed past measles, or birth before 1957, since most people born then were infected as children. Health care workers born before 1957 without lab evidence should consider 2 doses.

Children get 2 doses of MMR: the first at 12 to 15 months and the second at 4 to 6 years. One dose is about 93% effective against measles and two doses about 97%. Adults are recommended to have at least 1 documented dose, and some higher-risk adults need 2. If you are pregnant, wait until after pregnancy to get the vaccine.

Our clinic does not give vaccines: MMR is given by Puerto Rico Department of Health vaccination providers, and the Vaccines for Children (VFC) program provides it at no cost to eligible children (salud.pr.gov (opens in a new tab), in Spanish).

Many infections cause fever with a rash. Chickenpox causes itchy blisters that come in crops. With mono, the CDC warns that taking amoxicillin or ampicillin can bring on a measles-like rash. Children have many other causes: see rashes in children.

What points most to measles is the sequence: high fever with cough, runny nose and red eyes, then a few days later red spots that start on the face and move down, especially in someone unvaccinated or recently near a case. Only a lab test confirms it.

If you were near someone with measles:

According to the CDC, as of October 8, 2026, 4,080 confirmed measles cases had been reported in the United States in 2026, from 47 jurisdictions and among international visitors, with 42 new outbreaks. Puerto Rico was not on that page’s list of jurisdictions with cases. The CDC updates these numbers weekly.

If you are traveling, or hosting visitors from places with outbreaks, make sure your vaccines are up to date. With any warning sign, go to the emergency room and call ahead, or call 911.

Last updated: October 9, 2026.