The World Health Organization today has issued a statement on their GAR (Global Alert and Response) site regarding this year’s resurgence of measles around the globe.
This is a topic I’ve covered recently in:
While many parents today think of measles as a relatively benign childhood illness, it actually causes significant morbidity and mortality - often producing respiratory, ocular, and neurological complications – and sometimes resulting in death.
During the 1950s – before the introduction of the measles vaccine – in the United States alone the disease infected roughly 4 million, hospitalized nearly 50,000, and contributed to the deaths of several hundred every year.
Measles was considered eliminated in the United States by the year 2000 due to the great success of the of the measles vaccine introduced in the mid-1960s.
Measles is incredibly contagious (at least among those without immunity), but is easily preventable by vaccination.
With an R0 (R-naught) of about 15 (the number of new cases in a susceptible population likely to arise from a single infection), measles is nearly 10 times more contagious than seasonal flu, and greater than 3 times more so than SARS.
Lower vaccine uptake, and increases in international travel, have increased opportunities for the measles virus to spread – even to areas that had previously all but eliminated it.
Today’s WHO statement provides information on the size and location of this year’s outbreaks.
In 2011 several large measles outbreaks have been reported from member states in the European and African regions, with several reported outbreaks in the Americas linked to Europe or Africa.
Europe: According to case-based and aggregated routine surveillance reporting, and outbreak reports provided to the European Regional Office, as of 20 September 2011, 40 of 53 Member States reported 26 025 confirmed measles cases from January to July 2011. The highest number of cases was reported from France with 14 025 for the first six months of the year. In addition, eleven of these cases were lethal (6 in France and one in each of Germany, Kyrgyzstan, Romania, the Former Yugoslav Republic of Macedonia and the United Kingdom). The predominant genotype currently circulating in the European Region is D4, the same endemic genotype from the United Kingdom in 2008. The most recent outbreak was reported from Israel in September, with 12 cases. Member states have responded to the outbreak by modifying the vaccination schedule, with France adopting a two-dose schedule, by offering vaccination free of charge, or by offering vaccinations in schools.
Africa: The Regional Office reports that as of September 2011 large measles outbreaks are occurring in the Democratic Republic of the Congo with over 103 000 cases, Nigeria (17 428 cases), Zambia (6295 cases), Ethiopia, (1408 cases) and Kenya (1995 cases). Even though deaths are not routinely reported to the Regional Office, the WHO Country Office in the Democratic Republic of the Congo reports over 1100 measles-associated deaths in the country during 2011.
Americas: The last case of endemic measles was reported from the region in 2002. In 2011 the Region has received reports of several outbreaks linked to importation of measles virus from other regions. The largest, in Quebec, Canada, involves 742 reported cases, 89 requiring hospitalization, but no measles-associated deaths. Other outbreaks have been reported from the United States (213 cases), Ecuador (41 cases), Brazil (18 cases), Colombia (7 cases), Mexico (3 cases), and Chile (6 cases). Most of these outbreaks are linked to importations from Europe, except for outbreaks in the United States and Chile linked to cases from Malaysia and the outbreak in Ecuador, linked to Kenya.
Measles is a highly infectious disease that causes complications and deaths, even in previously-healthy individuals, but is fully preventable by vaccination. Countries need to ensure that they reach 95% coverage with two doses of measles vaccine across all age groups up to 15 years of age. Otherwise the country will experience measles outbreaks with large numbers of cases, associated hospitalizations and deaths. The recent outbreaks in countries with high volumes of international travellers can lead to measles exportation to regions previously free of measles, such as the Region of the Americas or certain African countries. These exportations can lead to large outbreaks and associated deaths.
These outbreaks should remind travellers that they should ensure that they have had two doses of measles-containing vaccine before their trip.