The Effect of Measles on Immunity

By Iva Fedorka 

Recent studies confirm that individuals infected with the measles virus also experience other immune system changes that can affect their overall health for significant and extended periods of time.

This understanding may help explain the true extent of health safety provided by measles vaccinations. By protecting one’s immune system from a measles virus attack, greater protective effects against other pathogens are simultaneously produced.

The Measles Virus

Measles, or rubeola, is a highly contagious disease caused by an RNA virus. Passed via airborne/respiratory routes, it causes systemic illness in humans and other primates. Symptoms include fever, skin rash, and also coughs, upper respiratory inflammation (cold-like congestion and mucus), and conjunctivitis (eye irritation).

When someone with the measles coughs or sneezes, the virus can survive for as long as two hours. In its new host, it targets immune cells in the nasal and pharyngeal mucosa, the lung alveoli, and the tissue between the eyelid and cornea. The virus then multiplies inside the cells, and spreads to the bone marrow, thymus, spleen, tonsils, lymph nodes, and other areas of immune cell concentration. Eventually, new viral particles move to the respiratory tract to be passed on to others.

Acute infections can last for several weeks, and symptoms appear between seven and ten days after exposure. People are the most contagious from days four through eight, when they have fevers, runny noses, and coughs, but may not yet have a rash.

Immune Suppression

Measles symptoms are uncomfortable, but it’s important to note that the disease also causes a temporary loss of immune cells that can increase one’s susceptibility to ear and other infections, pneumonia, and diarrhea.

“The virus has an enormously strong predilection to infect cells of the immune system,” said Bert Rima. An infectious disease researcher at Queen’s University Belfast in Northern Ireland, Rima and his colleagues reported on their findings of immune system invasion in preserved human tissue in 2018.

In 2013, virologist Rik de Swart of Erasmus University Medical Center in the Netherlands and his colleagues studied children in a Netherlands community of Orthodox Protestants. In the “Dutch Bible Belt,” parents refuse to vaccinate their children, which leads to regular measles outbreaks. The last outbreak ended in 2000, so the next occurrence was expected.

The parents gave permission to collect blood samples from their healthy, unvaccinated children. The new outbreak started as soon as sampling began, and the group successfully collected “before” and “after” samples from 77 children.

“The virus preferentially infects cells in the immune system that carry the memory of previously experienced infections,” de Swart says. These memory B and T white blood cells help the body react quickly when infectious threats recur. The study found a decrease in these memory cells, which creates an “immune amnesia,” as reported in a 2018 issue of Nature Communications.

The Aftereffects

The immune system may need months to years to regain full function. Researchers, including de Swart and Michael Mina, an infectious disease epidemiologist and pathologist at Harvard University, looked at the health records of children in the U.K. from 1990 to 2014. As reported in BMJ Open in 2018, children who had had measles were more likely than non-infected children to be treated for another infection within the five years following their bout with the disease.

Mina and colleagues reviewed medical records in Denmark, England, Wales, and the U.S., and found similar results. During outbreaks, non-measles infections were more likely to be fatal to children who also contracted the measles. The connection was even greater when they examined records from several years afterward.

“Every little blip in the mortality data could be explained by the measles incidence data over the previous 30 months,” Mina said.

Recovery

New research methods may help us better understand how the immune system eventually recovers. And, although measles are uneventful infections for most children, it is still not a harmless childhood disease. Moreover, we have a vaccine.

“Wherever you introduce measles vaccination, you always reduce childhood mortality. Always,” said de Swart.

“At the end of the day, we know how to prevent this potentially lethal disease,” Mina said. “It’s so simple.”