epidemiology of measles epidemiology of measles measles is extremely contagious, but surviving the infection results in lifelong immunity, so its continued circulation in a community depends on the generation of susceptible hosts by birth of children. in communities which generate insufficient new hosts the disease will die out. this concept was first recognized by bartlett in 1957, who referred to the minimum number supporting measles as the critical community size (ccs). analysis of outbreaks in island communities suggested that the ccs for measles is c. 250,000. due to the development of vaccination against measles, the world has seen a 99% decrease in measles related cases compared cases before the vaccine was developed. unfortunately, the covid-19 pandemic has created less of a concern of routine measles immunizations, and outbreaks are expected to occur if routine vaccinations of children are not implemented again. disability-adjusted life year for measles per 100,000 inhabitants in 2004. no data ≤ 10 10–25 25–50 50–75 75–100 100–250 250–500 500–750 750–1000 1000–1500 1500–2000 ≥ 2000 incidence reported cases who-region 1980 1990 2000 2005 2010 2015 2018 2019 2020 african region1,240,993481,204520,102316,219199,17452,758125,426 618,595115,369 region of the americas257,790218,5791,7548524761116,714 21,9711,548 eastern mediterranean region341,62459,05838,59215,06910,07221,41864,764 18,4586,122 european region492,660185,81837,42137,33830,62525,95789,148 106,13010,935 south-east asia region199,535224,92578,55888,97354,22848,88834,741 29,3899,389 western pacific region1,319,640155,490177,052128,01749,46065,17629,503 78,4796,599 worldwide3,852,2421,325,074853,479585,701343,806214,808360,296 873,022149,962 in 2018, the who estimated that there were around 353,236 cases of measles worldwide. this has since decreased as in 2020 there were 159,000 approximate cases. death from measles was reported in approximately 0.2% of the cases in the united states from 1985 through 1992. in populations with high levels of malnutrition and a lack of adequate healthcare, mortality can be as high as 10%. increased immunization has led to an estimated 78% drop in measles deaths among un member states. even in countries where vaccination has been introduced, vaccination rates may remain low due to parents choosing not to have their children vaccinated. in ireland, vaccination was introduced in 1985. there were 99,903 cases that year. within two years, the number of cases had fallen to 201, but this fall was not sustained. measles is a leading cause of vaccine-preventable childhood mortality. worldwide, the fatality rate has been significantly reduced by a vaccination campaign led by partners in the measles initiative: the american red cross, the united states centers for disease control and prevention (cdc), the united nations foundation, unicef and the who. globally, measles fell 60% from an estimated 873,000 deaths in 1999 to 345,000 in 2005. estimates for 2008 indicate deaths fell further to 164,000 globally, with 77% of the remaining measles deaths in 2008 occurring within the southeast asian region. in 2006–07 there were 12,132 cases in 32 european countries: 85% occurred in five countries: germany, italy, romania, switzerland and the uk. 80% occurred in children and there were 7 deaths. five out of six who regions have set goals to eliminate measles, and at the 63rd world health assembly in may 2010, delegates agreed a global target of a 95% reduction in measles mortality by 2015 from the level seen in 2000, as well as to move towards eventual eradication. however, no specific global target date for eradication has yet been agreed to as of may 2010. on january 22, 2014, the world health organization and the pan american health organization declared and certified colombia free of the measles while becoming the first latin american country to abolish the infection within its borders. in 2018, the who tells us the global annual incidence was about 46 million. during this time, the african region reported the most cases, about 40%, seen primarily from nigeria, and eastern mediterranean regions. in these specific areas, the incidence was greatly seen in those less than one year old. studies show that about 95% were immune by 15 years old, making it increasingly common for the incidence of measles to occur in young children. cases reported in the first three months of 2019 were 300% higher than in the first three months of 2018, with outbreaks in every region of the world, even in countries with high overall vaccination coverage where it spread among clusters of unvaccinated people. through the recent improvement of decreasing measles incidence and mortality rates across the world, recently there has been setbacks. since 2000, the mcv coverage around the world has decreased and the total cases of measles has increased from 132,490 in 2016, to 869,700 in 2019. though many countries have eliminated measles, several countries have discovered new cases in 2019. growing concern has been generating in increase cases of measles as incidence in measles have increased in recent years due to anti-vaccination movements due to religion and politics. measles eradication has been challenging for many countries to maintain herd immunity. due to political unrest, economic challenges, and accessibility to healthcare and proper vaccinations achieving proper vaccination levels in developing countries has halted. another challenge faced worldwide is vaccination hesitancy. the world health organization and centers for disease control and prevention have listed this is a top ten challenge to global health in reducing the incidence of measles. in april 2020, the who indicated that many countries had started suspending their measles vaccination programs due to the impact of the covid-19 pandemic. it is projected that 117 million children will be at risk of infection. currently all 194 countries have started to routinely vaccinate children with the mcv vaccine, and 122 countries have included the mmr into their routine child immunization schedules. outbreaks as measles contagion is high, it can spread rapidly through the population. the incubation period for measles is 10-12 days, and is characterized by seasonal epidemics, and spreads quickly against non-vaccinated persons. measles is quite uncommon in populations of highly vaccinated areas, yet when it does occur, it is more commonly seen in adults. the development of the measles vaccine has been vital in reducing outbreaks. without a measles vaccine, measles epidemics could happen every 2 to 5 years and last up to 3 to 4 months at a time. commonly outbreaks in one country spread to others and this can be traced by close examination of the virus dna. as of 2020 measles is widespread and there have been over the last decade many outbreaks in areas that were formerly declared measles free. see below for individual countries by continent. some examples of measles spreading between countries are: as of may 2011, over 17,000 cases of measles had so far been reported from france between january 2008 and april 2011, including 2 deaths in 2010 and 6 deaths in 2011. over 7,500 of these cases fell in the first three months of 2011, and spain, turkey, macedonia, and belgium have been among the other european countries reporting further smaller outbreaks. the french outbreak has been specifically linked to a further outbreak in quebec in 2011, where 327 cases have been reported between january and june 1, 2011, and the european outbreaks in general have also been implicated in further small outbreaks in the us, where 40 separate importations from the european region had been reported between january 1 and may 20. in 2014 many unvaccinated us citizens visiting the philippines, and other countries, contracted measles, resulting in 288 cases being recorded in the united states in the first five months of 2014, a twenty-year high. in vietnam, in the measles epidemic in the beginning of 2014, as of april 19 there were 8,500 measles cases and 114 fatalities, and as of may 30 there were 21,639 measles cases and 142 fatalities. the increase of measles in january and february of 2022 sparked concern due to the covid-19 pandemic and the displacement of millions due to conflict crises. this includes ukraine, ethiopia, somalia, and afghanistan as this disrupts the routine immunization schedule and the primary focus is the safety of citizens. european reservoir it has proven difficult to vaccinate a sufficient number of children in europe to eradicate the disease, because of opposition on philosophical or religious grounds, or fears of side-effects, or because some minority groups are hard to reach, or simply because parents forget to have their children vaccinated. vaccination is not mandatory in some countries in europe, in contrast to the united states and many latin american countries, where children must be vaccinated before they enter school. africa congo