(CNN) At least 10 US states have reported cases of measles so far in 2019, including Washington, where an outbreak is to blame for 50 cases.
Measles is a highly contagious disease caused by a virus that can spread through the air when an infected person coughs or sneezes, or if a person comes into direct contact or shares germs by touching the same objects or surfaces. High fever, rash all over the body, stuffy nose and reddened eyes are typical measles symptoms, though these usually disappear without treatment within two or three weeks.
But along with causing those symptoms, measles can also lead to death, according to the US Centers for Disease Control and Prevention.
So how do people die of the measles? They succumb when complications become too severe. About 1 child out of every 1,000 who get measles will develop encephalitis -- swelling of the brain -- that can lead to convulsions, deafness or intellectual disability. As many as 1 out of every 20 children with measles will get pneumonia, which can also be deadly, the agency reports.
Unvaccinated young children are at highest risk of measles and its complications, including death, according to the World Health Organization. Older children and adults, even if they've never been vaccinated, may have developed natural immunity through previous infections.
Complications can usually be avoided if a patient receives adequate supportive care, including good overall nutrition, sufficient fluids and, if needed, treatment for dehydration: replacement of fluids lost due to diarrhea and vomiting, WHO reports. Doctors generally prescribe antibiotics for patients who develop eye and ear infections or pneumonia.
Supplements of vitamin A, which supports the immune system and the eyes, have been shown to reduce the number of deaths from measles by 50%, WHO reports. A measles infection can cause low vitamin A levels even in well-nourished kids, so supplements can help restore normal levels as the body heals, while helping prevent eye damage and blindness. Even children in the best of health who are diagnosed with measles should receive two doses of vitamin A supplements 24 hours apart, according to WHO.
Since 1963, when the the vaccine was introduced, cases and deaths from measles in the United States and other developed countries have plummeted.
Prior to the vaccine, measles caused approximately 450 to 500 deaths each year in the United States. Between 1985 and 1992, death from measles was reported in approximately 2 out of every 1,000 US measles cases, with pneumonia accounting for about 60% of these deaths, according to the CDC. As of 2000, measles was declared eliminated in the United States or no longer constantly present, though spot outbreaks occur. The most recent measles death in the United States occurred in 2015, according to the CDC.
Before widespread use of the vaccine, measles led to more than 2 million deaths a year, according to WHO. Vaccination resulted in an 80% drop in worldwide measles deaths between 2000 and 2017. Around the globe, measles infections were responsible for 110,000 deaths in 2017, the most recent statistical year. Most of them were children under 5.
The overwhelming majority -- more than 95% -- of measles deaths occur in countries with low per capita incomes and weak health infrastructures, such as nations experiencing or recovering from a natural disaster or conflict. Disrupted health services, including routine vaccinations, along with overcrowding in residential camps increases the risk of infection.
Known as the MMR or measles, mumps and rubella vaccine, the vaccine is very effective, the CDC says. One dose is about 93% effective at preventing the contagious disease if you come into contact with the virus. Two doses are about 97% effective. It is recommended that children receive the vaccine in two doses: the first between the ages of 12 months and 15 months and the second between the ages of 4 and 6 years old.
With any medicine, including vaccines, there is a chance of reactions, according to the CDC. These are usually mild and go away on their own, but serious side effects and injuries are also possible. "There is a very remote chance of a vaccine causing a serious injury," the agency notes, including deafness, long-term seizures, coma and brain damage or death.
In 2017, about 85% of the world's children received one dose of measles vaccine by their first birthday -- up from 72% in 2000, according to WHO, which calculates that for the period from 2000 to 2017, vaccination prevented an estimated 21.1 million deaths due to measles.