Importation Of Measles Research Articles

Measles CEA

Abstract Background Most measles importations are due to returning US travelers infected during international travel. We projected clinical outcomes and assessed cost-effectiveness of pretravel evaluation for measles immunity and MMR vaccination among eligible adult US international travelers. Methods We designed a decision tree to investigate pretravel evaluation compared with no evaluation from the societal perspective. Data from the Global TravEpiNet Consortium and published literature informed input parameters (Figure 1). Outcomes included measles cases averted per 10 million travelers, costs, and the incremental cost-effectiveness ratio (ICER, Δcosts/Δmeasles cases averted); we considered ICERs < $100,000/measles case averted to be cost-effective. We performed sensitivity analyses to assess the impact of varying the probability of exposure based on travel destination, and the percentage of travelers with pre-existing measles immunity. Results In the base case, departure after pretravel evaluation resulted in 16 measles importations and 46 transmissions per 10 million travelers and cost $132 million, vs without pretravel evaluation (26 importations and 87 transmissions per 10 million travelers, costing $22 million). Pretravel evaluation averted 51 measles cases per 10 million travelers with an ICER of $2.2 million per case averted. Results were most sensitive to the probability of measles exposure and the traveler’s pre-existing immunity (Figure 2). Pretravel evaluation was cost-effective for travelers to Asia if pre-existing measles immunity was <80%. Evaluation was always cost-effective for travelers to Africa when pre-existing immunity was less than 100% and became cost saving when the percentage of immune travelers was lower (<70%). Travelers who were more likely to be non-immune and were visiting destinations with higher probabilities of exposure were most likely to benefit from pretravel evaluation for measles immunity at excellent economic value. Conclusion As risk of measles exposure increases and likelihood of travelers’ pre-existing immunity decreases, it can be cost-effective or cost saving to assess US international travelers’ measles immunity status and vaccinate with MMR prior to departure. Disclosures All authors: No reported disclosures.

Public Health and Economic Consequences of Vaccine Hesitancy for Measles in the United States

Routine childhood vaccination is declining in some regions of the United States due to vaccine hesitancy, which risks the resurgence of many infectious diseases with public health and economic consequences. There are ongoing policy debates on the state and national level, including legislation around nonmedical (personal-belief) exemptions for childhood vaccination and possibly a special government commission on vaccine safety, which may affect vaccine coverage. To estimate the number of measles cases in US children and the associated economic costs under scenarios of different levels of vaccine hesitancy, using the case example of measles, mumps, and rubella (MMR) vaccination and measles. Publicly available data from the US Centers for Disease Control and Prevention were used to simulate county-level MMR vaccination coverage in children (age 2-11 years) in the United States. A stochastic mathematical model was adapted for infectious disease transmission that estimated a distribution for outbreak size as it relates to vaccine coverage. Economic costs per measles case were obtained from the literature. The predicted effects of increasing the prevalence of vaccine hesitancy as well as the removal of nonmedical exemptions were estimated. The model was calibrated to annual measles cases in US children over recent years, and the model prediction was validated using an independent data set from England and Wales. Annual measles cases in the United States and the associated public sector costs. A 5% decline in MMR vaccine coverage in the United States would result in an estimated 3-fold increase in measles cases for children aged 2 to 11 years nationally every year, with an additional $2.1 million in public sector costs. The numbers would be substantially higher if unvaccinated infants, adolescents, and adult populations were also considered. There was variation around these estimates due to the stochastic elements of measles importation and sensitivity of some model inputs, although the trend was robust. This analysis predicts that even minor reductions in childhood vaccination, driven by vaccine hesitancy (nonmedical and personal belief exemptions), will have substantial public health and economic consequences. The results support an urgent need to address vaccine hesitancy in policy dialogues at the state and national level, with consideration of removing personal belief exemptions of childhood vaccination.

Global importation and population risk factors for measles in New Zealand: a case study for highly immunized populations.

As endemic measles is eliminated through immunization, countries must determine the risk factors for the importation of measles into highly immunized populations to target control measures. Despite eliminating endemic measles, New Zealand suffers from outbreaks after introductions from abroad, enabling us to use it as a model for measles introduction risk. We used a generalized linear model to analyze risk factors for 1137 measles cases from 2007 to June 2014, provide estimates of national immunity levels, and model measles importation risk. People of European ethnicity made up the majority of measles cases. Age is a positive risk factor, particularly 0-2-year-olds and 5-17-year-old Europeans, along with increased wealth. Pacific islanders were also at greater risk, but due to 0-2-year-old cases. Despite recent high measles, mumps, and rubella vaccine immunization coverage, overall population immunity against measles remains ~90% and is lower in people born between 1982 and 2005. Greatest measles importation risk is during December, and countries predicted to be sources have historical connections and highest travel rates (Australia and UK), followed by Asian countries with high travel rates and higher measles incidences. Our results suggest measles importation due to travel is seeding measles outbreaks, and immunization levels are insufficient to continue to prevent outbreaks because of heterogeneous immunity in the population, leaving particular age groups at risk.

Public Health and Economic Consequences of Vaccine Hesitancy for Measles in the United States

Importance Routine childhood vaccination is declining in some regions of the United States due to vaccine hesitancy, which risks the resurgence of many infectious diseases with public health and economic consequences. There are ongoing policy debates on the state and national level, including legislation around nonmedical (personal-belief) exemptions for childhood vaccination and possibly a special government commission on vaccine safety, which may affect vaccine coverage. Objective To estimate the number of measles cases in US children and the associated economic costs under scenarios of different levels of vaccine hesitancy, using the case example of measles, mumps, and rubella (MMR) vaccination and measles. Design, Setting, and Participants Publicly available data from the US Centers for Disease Control and Prevention were used to simulate county-level MMR vaccination coverage in children (age 2-11 years) in the United States. A stochastic mathematical model was adapted for infectious disease transmission that estimated a distribution for outbreak size as it relates to vaccine coverage. Economic costs per measles case were obtained from the literature. The predicted effects of increasing the prevalence of vaccine hesitancy as well as the removal of nonmedical exemptions were estimated. The model was calibrated to annual measles cases in US children over recent years, and the model prediction was validated using an independent data set from England and Wales. Main Outcomes and Measures Annual measles cases in the United States and the associated public sector costs. Results A 5% decline in MMR vaccine coverage in the United States would result in an estimated 3-fold increase in measles cases for children aged 2 to 11 years nationally every year, with an additional $2.1 million in public sector costs. The numbers would be substantially higher if unvaccinated infants, adolescents, and adult populations were also considered. There was variation around these estimates due to the stochastic elements of measles importation and sensitivity of some model inputs, although the trend was robust. Conclusions and Relevance This analysis predicts that even minor reductions in childhood vaccination, driven by vaccine hesitancy (nonmedical and personal belief exemptions), will have substantial public health and economic consequences. The results support an urgent need to address vaccine hesitancy in policy dialogues at the state and national level, with consideration of removing personal belief exemptions of childhood vaccination.

International Importations of Measles Virus into the United States during the Post-Elimination Era, 2001–2015

BackgroundMeasles is a highly contagious vaccine-preventable disease that can lead to serious complications. Although measles was declared eliminated from the United States in 2000, measles cases and outbreaks continue to occur each year as a result of importations of the disease from countries in which it remains endemic. We describe the epidemiology of importations of measles virus into the US during the post-elimination era.MethodsMeasles is nationally notifiable in the USA and local and state health departments report confirmed measles cases to the Centers for Disease Control and Prevention (CDC). A case is considered internationally imported if at least some of the exposure period (7-21 days before rash onset) occurred outside of the USA, rash onset occurred within 21 days of entering the USA, and there was no known exposure to measles in the US during that time. We describe the demographic characteristics, source regions, and vaccination status of measles importations during 2001–2015.ResultsFrom 2001 to 2015, 2,012 measles cases were reported to CDC; 535 (27%) were imported. A median of 28 importations occurred each year (range: 18–80). The median age of imported cases was 18 years (range: <1–75 years), 50% were male, 87% were unvaccinated or had unknown vaccination status, and 63% reported travel to countries in the Western Pacific and European Regions of the World Health Organization during their exposure periods. Half of all imported cases had rash onset between January and April. Overall, 62% (n = 332) of importations occurred among US residents, varying from a low of 37% in 2001 to a high of 89% in 2014. One imported case occurred among a US resident too young to be vaccinated, and 15 (5%) occurred among US residents born before 1957 (presumed immune from natural disease), and thus were not vaccine preventable.ConclusionImportations of measles virus will continue to occur as long as measles remains endemic in many parts of the world. In the post-elimination era in the US, the majority of importations were among US residents, almost all of which were vaccine preventable. Our findings emphasize the importance of measles vaccination of individuals aged ≥6 months prior to international travel, per ACIP recommendations, and of supporting global measles control efforts.Disclosures All authors: No reported disclosures.

Importation of Measles into America: How a Travel Clinic Can Help Prevent the Next Outbreak

There were an increased number of cases of measles in the United States (US) in the year 2014 including a major outbreak of measles originating at an amusement park in California. A visitor to the park, who probably was infected with measles during travel abroad, was suspected to be the source patient in the outbreak. This placed vaccination of children with the measles, mumps and rubella (MMR) vaccine at the center of medical, social and even political debate. Our travel clinic is accessed by a large number of persons prior to their travel abroad. Those who are not immune to measles have an opportunity to receive the MMR vaccine at their pre-travel visit. 912 persons were evaluated for in-person travel consultation at our travel clinic in the period January to December 2013 and 963 persons were evaluated during the same period in 2014. In addition to the traditional travel vaccines, 70 doses of the MMR vaccine were administered in 2013. 92 doses of MMR vaccine were administered in 2014. 315 tests for measles serology were performed in 2013, and 350 was the corresponding number for 2014. As seen in our data, among the large number of travelers seen at our clinic, a considerable number was not immune to measles and they were provided the MMR vaccine. The travel clinic thus represents a unique opportunity to increase the uptake of the MMR vaccine in healthy individuals. When these individuals are tested and vaccinated, it helps protect them from infection when they travel abroad and also increases herd immunity against measles in their communities when they return home.

A unique measles B3 cluster in the United Kingdom and the Netherlands linked to air travel and transit at a large international airport, February to April 2014.

This report describes a joint measles outbreak investigation between public health officials in the United Kingdom (UK) and the Netherlands following detection of a measles cluster with a unique measles virus strain. From 1 February to 30 April 2014, 33 measles cases with a unique measles virus strain of genotype B3 were detected in the UK and the Netherlands, of which nine secondary cases were epidemiologically linked to an infectious measles case travelling from the Philippines. Through a combination of epidemiological investigation and sequence analysis, we found that measles transmission occurred in flight, airport and household settings. The secondary measles cases included airport workers, passengers in transit at the same airport or travelling on the same flight as the infectious case and also household contacts. This investigation highlighted the particular importance of measles genotyping in identifying transmission networks and the need to improve vaccination, public health follow-up and management of travellers and airport staff exposed to measles.

Assessment of the role of international travel and unauthorized immigration on measles importation to the United States.

Concerns have been raised about unauthorized immigrants importing measles to the United States (US). This potential risk has not been rigorously evaluated nor compared with the potential risk of measles importation by US residents traveling internationally or international travellers coming to the US. We compared the potential risk of measles importation from each of these populations. Using a cross-sectional, ecological design, we compared country-level measles vaccination and incidence data, for top (i) US resident international travel destinations, (ii) US-bound international travellers' home countries and (iii) home countries of unauthorized immigrants to the US. In 2014, US residents made 52.5 million trips to one of the top 10 international destinations. Five of these countries (10,958,000 US resident trips) had average first-dose measles vaccine coverage below 90%, and five (9,881,000 US resident trips) had average measles incidence over 1 case/100,000 population. Two of the 10 top US-bound international travellers' home countries (5,597,259 international visitors) had average first-dose measles vaccine coverage below 90%, whereas five (13,333,545 international visitors) had average annual measles incidence over 1 case/100,000 population). In 2012, of 11.2 million unauthorized immigrants living in the US, 8.9 million (79.0%) were born in one of the top 10 unauthorized immigrant home countries. Four of those countries had average first-dose measles vaccine coverage below 90% (1.3 million unauthorized immigrants), whereas three of these countries had average measles incidence over 1 case/100,000 population (950,000 unauthorized immigrants). Overall, there are 10 times more annual US visitors to high measles incidence countries than there are unauthorized immigrants in the US from high measles incidence countries. Efforts to prevent reestablishment of indigenous measles transmission in the US should focus on evidence-based risk assessments, highlighting a greater potential measles importation risk of from US residents travelling internationally than unauthorized immigrants coming to the US.

Case-based surveillance enhanced with measles virus detection/genotyping is essential to maintain measles elimination in Aichi Prefecture, Japan

BackgroundJapan was verified as having achieved measles elimination by the Measles Regional Verification Commission in the Western Pacific Region in March 2015. Verification of measles elimination implies the absence of continuous endemic transmission. After the last epidemic in 2007 with an estimated 18,000 cases, Japan introduced nationwide case-based measles surveillance in January 2008. Laboratory diagnosis for all suspected measles cases is essentially required by law, and virus detection tests are mostly performed by municipal public health institutes. Despite relatively high vaccination coverage and vigorous response to every case by the local health center staff, outbreak of measles is repeatedly observed in Aichi Prefecture, Japan. MethodsMeasles virus N and H gene detection by nested double RT-PCR was performed with all specimens collected from suspected cases and transferred to our institute. Genotyping and further molecular epidemiological analyses were performed with the direct nucleotide sequence data of appropriate PCR products. ResultsBetween 2010 and 2014, specimens from 389 patients suspected for measles were tested in our institute. Genotypes D9, D8, H1 and B3 were detected. Further molecular epidemiological analyses were helpful to establish links between patients, and sometimes useful to discriminate one outbreak from another. All virus-positive cases, including 49 cases involved in three outbreaks without any obvious epidemiological link with importation, were considered as import-related based on the nucleotide sequence information. Chain of transmission in the latest outbreak in 2014 terminated after the third generations, much earlier than the 2010–11 outbreak (6th generations). ConclusionSince 2010, almost all measles cases reported in Aichi Prefecture are either import or import-related, based primarily on genotypes and nucleotide sequences of measles virus detected. In addition, genotyping and molecular epidemiological analyses are indispensable to prove the interruption of endemic transmission when the importations of measles are repeatedly observed.

Measles in Latin America: Current Situation.

The Region of the Americas (North, Central, and South America and the Caribbean) successfully interrupted endemic measles transmission in 2002, but recent outbreaks in Latin America threaten to reverse this impressive achievement. Before widespread measles immunization in Latin America, measles was a common illness in early childhood and was associated with substantial mortality. During the 1960s, 600 000measles cases were reported annually in the Region of the Americas [1].Although measles vaccine was introduced during the 1960s, it was the creation of the World Health Organization (WHO) Expanded Program on Immunization in 1977 that marked the beginning of sustained decreases in case numbers. During 1970– 1979, Latin American countries reported 220 000 measles cases annually, with incidence rates of 47–116 cases/ 100 000 population [2]. The highest mortality rates occurred among young children; from 1971 through 1980, measles associated mortality was 14–55 measles-associated deaths per 100 000 infants and 8–54 deaths/100 000 children aged 1–4 years. By 1980, most countries in the region had established national immunization programs; however, the mean infant measles vaccine coverage in the region was only 42%. In 2002, after more than 30 years of successful strategies and joint efforts of many countries in the region, interruption of endemic measles transmission in the Americas was achieved [3]. However, isolated cases continue to occur, due to the importation of measles from other areas of the world, sometimes causing short chains of transmissions over a few months.

Epidemiologic Surveillance on Measles, Rubella and Congenital Rubella Syndrome. Spain

To achieve the goal of eliminating measles and rubella two key strategies have been defined: sustain very low level of population susceptibility and strengthen surveillance system by rigorous case investigation and rapid control measures implementation. Surveillance of measles, rubella and CRS are included into the Spanish Surveillance System (RENAVE); surveillance is mandatory, passive, nationwide and case-based with laboratory information integrated. Information flows from sub national to national level (National Centre for Epidemiology) and then, to the WHO-Europe through ECDC. In the final phase of elimination, good surveillance and documented evidences are keys. Information on epidemiology of measles, rubella and CRS cases and outbreaks, pattern of importation, genotypes circulating and performance of measles and rubella surveillance are required at national and international level. Also all investigated and discarded measles or rubella cases should be reported. Currently the system faces some challenges gathering needed information for documenting the elimination. As long as the disease incidence declines, increases difficulties in identifying clinical measles and rubella because of non-specific prodromal signs and atypical cases. Differential diagnosis for fever and rash including measles and rubella should be performed in all clinical settings. Three clinical specimens must be collected to confirm or discard cases and to allow the virus characterization in order to know the pattern of importation of measles and rubella.

Measles in our time: the US experience.

Measles in our time: the US experience.

Modeling Measles Transmission in the North American Amish and Options for Outbreak Response.

Measles outbreaks in the United States continue to occur in subpopulations with sufficient numbers of undervaccinated individuals, with a 2014 outbreak in Amish communities in Ohio pushing the annual cases to the highest national number reported in the last 20 years. We adapted an individual-based model developed to explore potential poliovirus transmission in the North American Amish to characterize a 1988 measles outbreak in the Pennsylvania Amish and the 2014 outbreak in the Ohio Amish. We explored the impact of the 2014 outbreak response compared to no or partial response. Measles can spread very rapidly in an underimmunized subpopulation like the North American Amish, with the potential for national spread within a year or so in the absence of outbreak response. Vaccination efforts significantly reduced the transmission of measles and the expected number of cases. Until global eradication, measles importations will continue to pose a threat to clusters of underimmunized individuals in the United States. Aggressive outbreak response efforts in Ohio probably prevented widespread transmission of measles within the entire North American Amish.

Multinational Measles Outbreak in Post-Elimination Era, Involves Three Countries of North America and a European Country in a Short Transmission Chain

Background: Four measles cases in Canada and one in the United States are linked to international importation of measles in Playa del Carmen, Quintana Roo, Mexico. Objective: To describe characteristics of transmission and not spillover to local population in Mexico. Material and Methods: The outbreak investigation was based on active search of cases and in the rapid monitoring of vaccination coverage in children aged 1 - 7 years old. Laboratory confirmation by Enzyme-Linked Immunosorbent Assay (ELISA) and molecular detection by Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) assay in throat swab and urine were done. Results: One transmission chain with three generations of cases was identified. The primary case was a 9-year-old boy who was infected in Wales, UK. His sisters aged 7 and 15 years old respectively, were the first generation of cases in Mexico. The second generation was related to the imported cases, and affected two Canadian tourists and an American woman aged 39 years old. A third generation occurred in Canada and affected an infant of 15 months of age and his sister aged 4 years old. The genotype D8 which was circulating in UK was identified in these patients. One probable case was detected in Quintana Roo, but was discarded by laboratory testing. The coverage with at least one dose of Measles-Mumps-Rubella (MMR) vaccine ranged from 95% to 99.5%. Conclusion: International travelers with no history of vaccination are at risk of acquiring measles even in countries that have interrupted endemic transmission. The high immunization coverage of measles containing vaccine could explain the absence of cases in Mexican population. Highlights: Multinational measles outbreak in a country without endemic transmission. The findings exhibit the importance of immunization in international travelers in the post-elimination era.

Screening of blood serum for markers of infection with measles, rubella, cytomegalovirus and Dengue Fever in Russian tourists

The aim of the study was in the differential specific diagnosis of viral infections of unknown etiology in patients who have recently returned from a trip to the countries of Southeast Asia and India. In 2013, SRC VB "Vector" examined single serum samples from 131 patients with suspected Dengue Fever. Dengue viral RNA was detected by means of polymerase chain reaction, NS dengue virus antigen and antibody classes M and G to Dengue virus - with the use of immunochromatographic methods and enzyme immunoassay. In the same sera the presence of specific IgM to measles, rubella and cytomegalovirus virus antigen was revealed by enzyme immunoassay and enzyme-enhanced chemiluminescence. As a result of examination 87 (66.4%) ofsamples were diagnosed as "Dengue fever". In seven out of the 87 samples there were detected specific class-M antibodies to cytomegalovirus. 44 sera (33.6%) out of 131 did not contain markers for Dengue fever. But 4 out of them contained IgM to measles virus, the other 5 sera contained IgM to rubella virus. Regional Centre of WHO laboratory confirmed three cases of measles, the one positive result for the content of IgM to rubella virus antigens results was interpreted as "equivalent." Identified in 2013 cases of importation ofmeasles and rubella by tourists from Southeast Asia and India have not resulted in the transmission of the disease through contact with others persons in Russia. In seven detected Dengue Fever cases opportunistic cytomegalovirus infection was revealed.

Record number of U.S. measles cases this year

A total of 288 confirmed measles cases have been reported to CDC from January 1 to May 23, with the majority of cases occurring in patients who were not vaccinated.1.www.cdc.gov/mmwr/preview/mmwrhtml/mm6322a4.htm?s_cid=mm6322a4_w.Google Scholar This represents the highest number of cases since measles elimination was documented in the United States in 2000. Pharmacists can play a significant role in helping to reduce the number of future measles cases by educating patients and caregivers about the importance of getting vaccinated, immunizing patients, and collaborating with other health care providers in the community to send consistent messages and form successful immunization neighborhoods. Measles cases have been reported in 18 states, with 15 outbreaks (i.e., defined as a chain of transmission of three or more confirmed cases) representing 79% of the reported cases.1.www.cdc.gov/mmwr/preview/mmwrhtml/mm6322a4.htm?s_cid=mm6322a4_w.Google Scholar The largest outbreak to date—138 cases and ongoing— is occurring among the unvaccinated in Amish communities in Ohio. California has the second highest number of cases, with 60 cases reported as of May 23. Most cases have occurred in patients who were not vaccinated and had traveled to other countries where measles outbreaks are more common. These travelers subsequently transmitted the disease to clusters of unvaccinated persons around them, as measles is a highly contagious disease. CDC identified importations from at least 18 countries, with a large number of cases occurring in travelers returning from the Philippines. CDC reported confirmed cases in patients aged 2 weeks to 65 years, with approximately one-half of cases occurring in patients younger than 20 years.1.www.cdc.gov/mmwr/preview/mmwrhtml/mm6322a4.htm?s_cid=mm6322a4_w.Google Scholar A confirmed measles case is one confirmed by laboratory testing or one that meets the clinical case definition of the disease, which includes a generalized rash lasting 3 or more days, a temperature greater than or equal to 101 °F, and cough, coryza, and/or conjunctivitis. In a minority of cases (15%), patients have been hospitalized with various complications ranging from pneumonia, hepatitis, pancytopenia, or thrombocytopenia. No cases of encephalitis or deaths have been reported as of May 23. The record number of measles cases highlights the importance of increased collaboration, coordination, and communication among immunization stakeholders to meet the immunization needs of patients and help protect the community from vaccine-preventable diseases. Equally important is providing reliable, consistent, unbiased, and easily understood information to patients, especially those who may be hesitant or question the vaccine’s value. Pharmacists should understand current recommendations for the measles- mumps-rubella (MMR) vaccine so they can identify which patients need the vaccine, educate patients and caregivers on the importance of obtaining the vaccine, administer the vaccine as allowed by state laws, and appropriately document and follow up with other providers to ensure continuity of care. Recognizing a measles caseMeasles is characterized by fever (as high as 105 °F) and malaise; cough, coryza, and/or conjunctivitis; and a pathognomonic enanthema (Koplik spots), followed by amaculopapular rash. The rash usually appears about 14 days after exposure; however, the incubation period ranges from 7 to 21 days. The rash spreads from the head to the trunk to the lower extremities (sometimes immunocompromised patients do not develop the rash). Patients are considered contagious from 4 days before to 4 days after the rash appears. The vaccine is currently recommended for all children, with the first dose given at age 12 months to 15 months and a second dose given at age 4 years to 6 years.1.www.cdc.gov/mmwr/preview/mmwrhtml/mm6322a4.htm?s_cid=mm6322a4_w.Google Scholar Catch-up vaccinations are recommended for children who have not received two properly spaced vaccinations. In addition, adults without immunity to the disease should receive at least one dose of the MMR vaccine, and two appropriately spaced doses of MMR are recommended for health care personnel, college students, and international travelers. Pharmacists should determine if patients will be traveling internationally and educate them on their increased risk for measles and the importance of timely vaccination for those without evidence of measles immunity.1.www.cdc.gov/mmwr/preview/mmwrhtml/mm6322a4.htm?s_cid=mm6322a4_w.Google Scholar CDC recommends that before traveling, infants aged 6 months to 11 months should receive one MMR dose, and those 12 months and older should be given two doses, with a minimum interval of 20 days between doses. CDC noted that health professionals should continue to work toward maintaining high vaccination coverage rates in the United States to limit measles importations and spread of the disease.1.www.cdc.gov/mmwr/preview/mmwrhtml/mm6322a4.htm?s_cid=mm6322a4_w.Google Scholar In addition, providers are encouraged to maintain a high level of awareness that measles cases are occurring more frequently in the United States, to implement appropriate infection control measures if measles is suspected, and to promptly report any suspected cases to local health departments.

The challenges of sustaining measles elimination in Canada.

Recent importations of measles into Canada have not generally led to large outbreaks, indicating that measles is well controlled in Canada. Isolated large outbreaks that have occurred remind us of the need to remain vigilant. Measles presents particular challenges because it is the most infectious disease known, it thrives among those who do not access the child health system for one reason or another, and we do not always have the information we need to identify and target communities with low immunization coverage. Outbreaks typically arise from Canadians who travel and are exposed to measles abroad. Controlling sporadic outbreaks arising from importations is time and resource intensive, which makes immunization for Canadians travelling outside the region of the Americas (where measles has been eliminated) a priority. To prevent importations of measles into Canada altogether requires other countries and regions of the world to make progress in eliminating measles.

Measles molecular epidemiology: What does it tell us and why is it important?

Measles molecular epidemiology was a key component of the verification of elimination of indigenous measles in Canada and is an invaluable tool during public health investigations, both to establish whether connections exist between concurrent measles cases and to indicate possible sources of importations. There are 24 distinct genotypes however the genotype is usually not sufficient to describe the complex molecular epidemiology of measles cases. The exact genetic sequence of the last 450 nucleotides of the nucleoprotein (N) gene (N-450) is used. The measles genome mutates very slowly and so cases within the same chain of transmission usually have identical N-450 sequences. In Canada, the National Microbiology Laboratory (NML) sequences the N-450 and deposits it into the WHO measles sequence database, MeaNS. This database can be used to identify other geographic regions where the measles sequence was detected, supporting or excluding connections. For commonly detected N-450 sequences, MeaNS designates a "sequence variant." Sequence variants are used as the defining characteristic of measles cases with identical sequences and this designation is fundamental to the description of measles molecular epidemiology both locally and globally. As progress is made towards global measles eradication, its genetic diversity decreases and distinct importations of measles from a single reservoir can be difficult to distinguish using current methods. Extending sequencing methods beyond the N-450 is required. While sequencing the entire hemagglutinin (H) gene, which is currently done routinely at the NML, can be helpful, whole genome sequencing will be required for effective molecular surveillance to monitor the sustained elimination of measles in Canada.insert text here.

Large Measles Outbreak in a Religious Community in British Columbia

In March 2014 an outbreak of measles commenced in a small religious school attended by around 350 children from families with extremely low MMR vaccination uptake. Within 4 weeks almost 400 cases were observed within the 1200 member congregation. Only four cases occurred unlinked to the congregation. While importations of measles into Canada are expected and rapid spread is possible in unimmunized communities, public health measures can control outbreaks.

Loss of Passively Acquired Maternal Antibodies in Highly Vaccinated Populations: An Emerging Need to Define the Ontogeny of Infant Immune Responses

Protection against infectious diseases is provided to young infants by passive immunity through the transplacental transfer of immunoglobulin G during pregnancy and through immunoglobulin A in breast milk [1–7]. Despite the obvious benefits of these antibodies to the youngest infants, their levels wane over time, necessitating the development of active immunity through vaccination. The timing of primary vaccination is complex, driven by the need to provide protection prior to a time when the infant is likely to be exposed to disease, by the possibility of interference with vaccine-induced immunity by passively acquired maternal antibodies, and, finally, by considerations of the developing infant immune system [7–9]. The titers of transplacentally transferred passive antibodies (PA) provided to infants are, in part, determined by antibody titers present in the mother during pregnancy. These maternal titers are affected by her nutritional and immune status, and evidence demonstrates that antibody titers induced by vaccination are typically lower than titers induced by natural disease [3, 5, 6, 10]. After decades of vaccination against childhood diseases, it is clear that successful vaccine programs have resulted in dramatic decreases in morbidity and mortality. However, the increasing prevalence of vaccine-derived maternal antibodies has also led to unexpected outcomes. This is most evident in the emergence of measles susceptibility in young infants living in highly vaccinated populations where the measles vaccine has been in use for decades [11–14]. Historically, in developed nations protection against measles among infants <12 months of age was provided by a combination of PA and herd immunity, supported by high population immunization rates. However, this barrier has been disrupted, to a certain extent, by global importation of measles and, paradoxically, by the success of the measles vaccine programs, as vaccine-induced PA wanes earlier in infants as compared to PA derived from maternal natural infection [4, 8, 15, 16]. Measles outbreaks in countries with high measles vaccine coverage have demonstrated a shift in measles incidence to children <12 months of age [17–19], before primary measles vaccination commences in most developed countries. Further, the number of susceptible infants aged <12 months is expected to increase among highly vaccinated populations as the majority of women in child bearing years have vaccine-induced immunity to measles, with recent studies showing 99% of infants born to vaccinated mothers lacking detectable antibodies to measles by 6 months [3, 4]. Waaijenborg and colleagues eloquently highlight this phenomenon in this issue of the Journal by comparing titers of antibodies against measles, mumps, and rubella in 2 distinct populations in the Netherlands, one with high vaccination rates and one with opposition to vaccination and, thus, low vaccination rates and presumably higher rates of immunity induced by natural disease. As with previous studies, the authors note significantly lower measles antibody titers in infants born to women from the highly vaccinated populations in comparison to those born to mothers with presumed naturally induced immunity. In addition, the authors also compared mumps and rubella titers in the 2 populations, showing higher rubella titers in mothers from the population with low vaccination rates and low levels of mumps titers in both groups. Varicella was used in this study as a “control” disease because it is caused by a naturally circulating virus in Received and accepted 7 March 2013; electronically published 8 May 2013. Correspondence: Hayley A. Gans, MD, 300 Pasteur Dr, Rm G 312, Stanford University School of Medicine, Stanford, CA 94305-5208 (hagans@stanford.edu). The Journal of Infectious Diseases 2013;208:1–3 © The Author 2013. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals. permissions@oup.com. DOI: 10.1093/infdis/jit144