Measles: increase in the number of cases worries and lights up alert for the whole Brazil

Publicação: 10 de May de 2022

The disease is one of the main causes of child mortality in third world countries

The disease is very severe, highly transmissible, with high lethality, has no treatment and prevention depends on vaccination

While discussing the vaccination of children and adolescents against Covid-19, the demand for other vaccines recommended for children has decreased significantly in recent months. Despite disposing of vaccines available to immunize the entire Brazilian population against measles, Brazil has again become one of the countries on alert for major outbreaks of the disease. This year, until March 26 the Ministry of Health registered 98 suspected cases of measles and 13 were confirmed, 12 in Amapá and two autochthonous cases in São Paulo, one of them (baby) who contracted the disease in São Paulo and not by transmission in another region. São Paulo also investigates another 25 cases.

Measles was already a major cause of infant mortality in the 80s and the vaccine helped reverse this situation. After the last cases in 2015, Brazil received the certificate of Autochthonous Measles Transmission Free Country in 2016, but autochthonous transmission of the virus reappeared in 2018 due to low vaccination coverage. According to the Epidemiological Bulletin of the Secretariat of Health Surveillance of the Ministry of Health (SVS/MS), in 2018 10,346 cases of the disease were confirmed. In 2019, after one year of free circulation of the virus, 20,901 cases were confirmed. In 2020 8,448 cases were reported, and in 2021, until Epidemiological Week (SE) 52, there were 668 cases. Also according to the document, in 2021, there were two deaths, both in Amapá, in children under one year old. Amapá, Pará, Alagoas, São Paulo, Ceará and Rio de Janeiro are, in this order, the states that registered the highest number of cases, mostly in children under one year old.

Dr. Pedro Fernando da Costa Vasconcelos, former president of the Brazilian Society of Tropical Medicine (SBMT), professor at the State University of Pará (UEPA) and virology researcher at the Evandro Chagas Institute (IEC), points out that the disease continues to have autochthonous transmission in the country, because we have low vaccination coverage, which served as the basis for this year’s new circulation. “If we had a high vaccination coverage, even if it had been reintroduced in Brazil, measles would not have remained. So, in order for us to eliminate it again, we must increase our vaccination coverage uniformly and not only in some states. Without reaching high vaccination coverages, it is impossible to discuss measles elimination in Brazil,” emphasizes the researcher. It is worth remembering that in 2020 Pará became the epicenter of the disease. In the same year, Rio de Janeiro had the first death (baby) after more than 20 years without recording deaths from the disease. In 2021, during the pandemic, there was an outbreak in 21 states.

Professor of Medicine at the Federal University of São Carlos (UFSCar), and director of the Oswaldo Cruz Foundation (Fiocruz), Rodrigo Stabeli, warns of the increase in measles cases in São Paulo, which lights a nationwide warning, since the city serves as a sentinel for the rest of the country. “As we have a very high population density and migration or passage flow, São Paulo ends up being a corridor for the disease, making it circulate from North to South, as it happens in the rest of the world. When there is free circulation, the important thing is to increase the vaccination campaign”, emphasizes the professor.

Dr. Dorcas Lamounier Costa, pediatrician and full professor of Pediatrics at the Federal University of Piauí (UFPI), agrees. According to her, the possibility of an outbreak in any region of Brazil is very high because vaccination coverage is far below the recommended minimum. She draws attention to the need to maintain broad vaccination coverage, above 95% to prevent outbreaks, which are so severe and so lethal. By the end of 2020, 81 countries had managed to maintain their measles elimination status despite the pandemic, but no new countries achieved elimination. “There are still 15 countries that have not introduced the second dose into their national immunization calendars, leaving children and adolescents in these countries especially vulnerable to measles outbreaks,” the pediatrician laments.

When it comes to the global context, Stabeli adds that the latest publication by the World Health Organization (WHO) showed that the disease increased worldwide in 2019, reaching the highest number of reported cases in the last 23 years. “Since 1996 there has been no significant increase and this happened even though we have a highly efficient vaccine. It is one of the most effective when it comes to public health and with which we have achieved a high worldwide vaccination coverage. Vaccination campaigns, when conducted with seriousness and political will, achieve a high degree of success,” he adds. According to Dr. Stabeli, while the antivax groups make their counter-propaganda, the population has the feeling that the disease no longer exists, because its rarely heard of. For example, much was said about measles in 2018 and after that, it was as if the disease had disappeared, it was no longer a threat. Data from the Department of Informatics of the Unified Health System (DataSUS) show that last year just over 49% of the population had both doses of the immunizing against measles.

“In addition, in the last two years, the measures of social distancing imposed for the prevention of transmission of SarsCov2 have also influenced the transmission of measles, giving the false sense of security regarding this important disease. In the same period there was an even greater drop in immunization rates and now that the measures of distancing are reduced, it is quite possible that many cases of measles are detected throughout Brazil, as well as throughout the world”, adds Dr. Costa.

Vaccine protects against genotype D8

Asked if the current viruses that are in circulation would be mutations of those that caused previous outbreaks, Dr. Vasconcelos explains that there is only one measles serotype, what exists are different genotypes or subtypes. “Currently we have only one genotype circulating in Brazil, which is slightly different from those that circulated in the last century. Since measles is an RNA virus, the chances of mutation are higher than DNA viruses, so naturally during viral replication, mutations can occur due to a certain ‘infidelity’ of viral polymerase generating new viral genetic strains,” the virologist explains.

And how does this affect the vaccines’ effectiveness? Dr. Vasconcelos mentions that there are different subtypes (A – H) and genotypes (total of 24 genetic strains) and currently a genotype circulating in Brazil, D8, has been detected. “This genotype is slightly different from those that circulated decades ago when the virus was endemic in Brazil; this genetic lineage is not included in the formulation of the current vaccine used for immunization, which is prepared using subtype A. But since there is only one viral serotype, although the D8 genotype currently circulating is not the same used in the vaccine formulation, there is still a partial protective ability, says Dr. Vasconcelos.

Challenge to brake transmission

Dr. Costa draws attention to the risk of measles, one of the most contagious infectious diseases known. To have an idea, in certain situations, the basic reproduction number (R0) can reach 12: this means that a sick person can pass the virus to another 12. If vaccination coverage is low, there is a high possibility that these secondary cases will also get sick and that each of them transmits the virus to 12 other people and so on.

Also according to the pediatrician, the only way to stop transmission is through vaccination. “The best would be to keep people vaccinated through a continued national routine immunization program. But, under a risk situation, after the detection of a case, it is necessary to implement this program with what is called blocking vaccination, which should be carried out no later than 72 hours after contact with the suspected or confirmed case, in order to interrupt the transmission chain and, consequently, vaccinate those who are not vaccinated from 6 months of age in the shortest possible time. As blockade vaccination intensifies, it is necessary to carry out extensive active search for new suspected and susceptible cases for more efficient control of the disease,” she advises.

Finally, dr. Vasconcelos highlights the need to intensify awareness campaigns about the need to increase the rates of vaccine coverage of immunopreventable diseases (of all of them) in order to sensitize the population to get vaccinated, and thus, allow the country to create conditions to once again think about the elimination of measles. Without increasing the rate of vaccination coverage, there is no way to eliminate measles, and we will have to learn to live with this terrible disease in Brazil, and certainly many deaths and severe cases unfortunately will be recorded”, he warns.

Dr. Costa agrees and recognizes that Brazil has the weapons, vaccines, to prevent a major outbreak from saturating medical services. The country has availability of vaccines and one of the most complex and organized immunization networks in the world. The National Immunization Program (PNI) has the ability to perform blockade vaccination campaigns and improve routine vaccination coverage in a short period of time,” concludes Dr. Costa. According to the Ministry of Health, the child’s public is made up of 12.9 million children. The goal is to immunize 95% of this age group. To operationalize the strategy, 14.8 million doses of the triple viral vaccine will be distributed. However, the slowness threatens to contain the spread of the measles virus. The immunization program started in April 2022, expected to immunize more than 18 million people, has so far vaccinated just over 400 thousand.

Suspected case definition:

A suspected case of measles is considered to be any individual who, regardless of age and vaccination status, has fever and maculopapular rash, accompanied by one or more of the following symptoms: cough and/or runny nose and/or conjunctivitis

A person with fever and maculopapular rash, accompanied by cough and/or runny nose and/or conjunctivitis, regardless of age and vaccination status; every individual considered as a suspected case, with a history of traveling abroad in the last 30 days, or contact with someone who traveled to places with measles virus circulation, in the same period.

All patients considered suspected of having measles should be notified and laboratory investigated.

Main symptoms

The main symptoms include: fever accompanied by cough; eye irritation; runny or stuffy nose; intense malaise. Around 3 to 5 days, red spots appear on the face and behind the ears that then spread throughout the body. After the appearance of the spots, the persistence of fever intensifies for a few more days; persistent fever three days after the onset of spots is a warning sign and may indicate severity, especially secondary bacterial infections, very common in children under 5 years of age.

There is no specific treatment for measles and medications can only reduce the discomfort caused by the symptoms of the disease. However, measles is a vaccine-preventable disease. In Brazil the vaccine is available in the public network. Double viral vaccines, which protect against measles and rubella, are used for vaccine blockade in an outbreak situation. Routinely, the Ministry of Health recommends triple viral (which protect against measles, mumps and rubella) or tetra viral (which protect against measles, mumps and rubella and chickenpox) vaccines. All of them are effective in preventing measles and it is up to the health professional to apply the appropriate vaccine to each person, according to age and epidemiological situation.

Inquired by the communication office of the Brazilian Society of Tropical Medicine (SBMT) to talk about the subject, the Ministry of Health did not respond until the end of this edition.