Costa Rica has been measles-free since 2014 — until now. A five-year-old French child who was on vacation with his family has been diagnosed with the disease, becoming the first case the country has had in almost five years.

A transmission electron micrograph (TEM) of a single virus particle, or “virion”, of measles virus. Image credits: Cynthia S. Goldsmith / CDC.

Since the introduction of vaccines, the number of measles cases worldwide has been dramatically reduced. But in recent years, measles has made a small but worrying resurgence in the developed world, riding the waves of non-scientific antivaxxing trends. Just a few weeks ago, the World Health Organization (WHO) warned about the dangers of preventable diseases making a comeback, calling “vaccine hesitancy” among the 10 most serious threats to human health.

“Some countries that were close to eliminating measles have seen a resurgence,” the WHO warned.

As if to illustrate that point, Costa Rican authorities have now reported that a family of French tourists, the parents 30 and 35 years of age and their 5-year-old child, have been placed in isolation at the Puntarenas Hospital, close to where the family was on vacation. The boy presented a measles-like rash, and blood tests have confirmed that he does have measles (Costa Rican doctors also found that other children at the boy’s kindergarten also had measles).

This didn’t necessarily come as a surprise to Costa Rican authorities, who were on alert for measles being reintroduced from other countries. Costa Rica didn’t have any native measles cases since 2006, but imported cases have been reported up until 2014.

“An increase in cases of measles was first reported last year in Europe and some areas of the United States, but recently, several countries in Latin America have also raised the alarm; for this reason, health authorities in Costa Rica are on alert and have began promoting a vaccination campaign that will take place in August,” a recent local news report stated.

Measles is a highly contagious disease caused by a virus. It has very unpleasant symptoms and can lead to dangerous and potentially fatal complications. Vaccination is 97% effective against the measles virus, which has been instrumental in reducing measles cases around the world. In the developing world, access to vaccination is still a problem, the WHO says.

“Measles vaccination resulted in a 80% drop in measles deaths between 2000 and 2017 worldwide. Even though a safe and cost-effective vaccine is available, in 2017, there were 110 000 measles deaths globally, mostly among children under the age of five,” the WHO reports. Before the introduction of measles vaccine, major epidemics occurred approximately every 2–3 years and measles caused an estimated 2.6 million deaths each year.

Measles cases reported in the US, 1944-2007. Other countries where vaccines were widely implemented display similar trends. Credits: CDC.

Worryingly, even in countries which had all but eradicated measles, the disease is making a comeback as a result of reduced vaccination. Antivaxxing trends and complacency are stopping some parents from getting their children vaccinated. People opting not to have their kids vaccinated are posing great threats not only to themselves, but also to others.

In France, vaccinations against measles and 11 other diseases compulsory for children, as the current health ministry has made vaccination one of its top priorities. It’s not currently clear why the boy has not yet been vaccinated.

Thankfully, the boy is now in safe hands, and there are good odds that the quarantine will be successful. The family will be held for at least a week at the hospital, and authorities are trying to figure out who the boy was in contact with.

Costa Rica provides universal health care to all its citizens and is constantly ranked as the country with the best health care in Latin America, and one of the best in the world. A recent WHO report ranked Costa Rica just ahead of the US in terms of healthcare efficiency.

The CDC advises all travelers to take their vaccines before traveling to Costa Rica: “Make sure you are up-to-date on routine vaccines before every trip. These vaccines include measles-mumps-rubella (MMR) vaccine, diphtheria-tetanus-pertussis vaccine, varicella (chickenpox) vaccine, polio vaccine, and your yearly flu shot,” the CDC page reads.