Public health officials are closely monitoring a resurgence of measles in the Americas, with cases continuing to rise in early . The Pan American Health Organization (PAHO) issued an epidemiological alert on , calling on countries to strengthen surveillance, vaccination efforts, and rapid response measures to interrupt transmission and protect vulnerable populations.
Rising Cases Across the Region
In , a total of 14,975 confirmed measles cases were reported in 13 countries across the Americas, including 29 deaths. This represents a dramatic 32-fold increase compared to the 466 cases recorded in . Countries reporting cases included Argentina (36), Belize (44), Bolivia (597), Brazil (38), Canada (5,436, including 2 deaths), Costa Rica (1), El Salvador (1), the United States (2,242, including 3 deaths), Guatemala (1), Mexico (6,428, including 24 deaths), Paraguay (49), Peru (5), and Uruguay (13).
The trend has continued into , with an additional 1,031 confirmed cases reported in the first three weeks of the year across seven countries: Bolivia (10), Canada (67), Chile (1), the United States (171), Guatemala (41), Mexico (740), and Uruguay (1). No deaths have been reported during this period. This represents a 43-fold increase compared to the 23 cases reported in the same timeframe in .
Vulnerability and Vaccination Status
Data indicates that vaccination remains the most effective preventative measure against measles. Among confirmed cases where vaccination status was known, 78% were unvaccinated, and in 11% of cases, vaccination history was unknown. While the majority of cases occurred in adolescents and young adults, the highest incidence rates were observed in children under one year of age, followed by those aged 1 to 4 and 5 to 9 years, highlighting the critical need for complete vaccination schedules.
Measles is a highly contagious viral disease that primarily affects children. It spreads through droplets released when an infected person coughs or sneezes. Initial symptoms, typically appearing 10-12 days after infection, include high fever, runny nose, bloodshot eyes, and small white spots inside the mouth. A rash then develops, starting on the face and spreading downwards. While most people recover within 2-3 weeks, measles can lead to serious complications, particularly in malnourished children and those with weakened immune systems, including blindness, encephalitis (brain swelling), severe diarrhea, ear infections, and pneumonia.
Global Resurgence and Vaccination Coverage
The Americas are not alone in experiencing a measles resurgence. Globally, the World Health Organization (WHO) reported over 552,000 suspected measles cases in 179 countries in , with approximately 45% (247,623) confirmed. This reflects a broader global trend of increasing cases linked to gaps in immunization coverage.
Regional vaccination coverage with the measles, rubella, and mumps (MRP) vaccine in the Americas showed a slight improvement in compared to (from 87% to 89% for the first dose and from 76% to 79% for the second dose). However, coverage remains below the 95% threshold recommended to prevent outbreaks. Only 33% of countries and territories in the region achieved 95% or higher coverage with the first dose, and only 20% reached that goal with the second dose. An estimated 1.5 million children did not receive any dose of the MRP vaccine in .
PAHO Recommendations and Ongoing Monitoring
PAHO recommends strengthening surveillance and active case finding, including laboratory diagnosis, implementing supplementary immunization activities to close immunity gaps, and ensuring a timely response to any suspected cases. The organization emphasizes the importance of closing coverage gaps, maintaining sensitive and timely surveillance, and protecting travelers through vaccination, especially those traveling to areas with active transmission.
Given the upcoming FIFA World Cup and other mass gatherings involving significant population movement, PAHO recommends that countries enhance the sensitivity of their surveillance systems through active case searches to promptly detect the presence or absence of measles and rubella cases.
PAHO will continue to monitor the measles situation and update its recommendations as the epidemiological situation evolves. The measles vaccine has proven highly effective, preventing 6.2 million deaths in the Americas and 93.7 million worldwide since 1974. Investments in measles immunization have yielded a return of US$76.5 for every US$1 invested in vaccination in low and middle-income countries.
