Importation Of Measles Research Articles

Largest Measles Epidemic in North America in a Decade—Quebec, Canada, 2011: Contribution of Susceptibility, Serendipity, and Superspreading Events

The largest measles epidemic in North America in the last decade, occurred in 2011 in Quebec, Canada, where rates of 1- and 2-dose vaccine coverage among children 3 years of age were 95%-97% and 90%, respectively, with 3%-5% unvaccinated. Case patients identified through passive surveillance and outbreak investigation were contacted to determine clinical course, vaccination status, and possible source of infection. There were 21 measles importations and 725 cases. A superspreading event triggered by 1 importation resulted in sustained transmission and 678 cases. The overall incidence was 9.1 per 100,000; the highest incidence was in adolescents 12-17 years old (75.6 per 100,000), who comprised 56% of case patients. Among adolescents, 22% had received 2 vaccine doses. Outbreak investigation showed this proportion to have been an underestimate; active case finding identified 130% more cases among 2-dose recipients. Two-dose recipients had milder illness and a significantly lower risk of hospitalization than those who were unvaccinated or single-dose recipients. A chance superspreading event revealed an overall level of immunity barely above the elimination threshold when unexpected vulnerability in 2-dose recipients was taken into account. Unvaccinated individuals remain the immunization priority, but a better understanding of susceptibility in 2-dose recipients is needed to define effective interventions if elimination is to be achieved.

Measles virus genotyping an important tool in measles outbreak investigation in Norway, 2011

This study describes 33 laboratory-confirmed cases of measles that occurred in Norway in 2011, mainly among unvaccinated children between seven months and 10 years of age. Laboratory testing included detection of anti-measles IgM- and IgG antibodies by enzyme-linked immunosorbent assay (ELISA) and molecular detection and characterisation of measles virus by polymerase chain reaction (PCR) and sequencing. Epidemiological data and genotyping revealed that the measles cases originated from eight separate importations, resulting in four outbreaks and four sporadic cases. Except for the first outbreak which affected 18 cases, limited secondary spread occurred in each of the three other outbreaks. The outbreaks were caused by measles virus genotypes B3, D4 and D9, whereas genotypes D8 and B3 were detected in the sporadic cases. This study highlights that genetic characterisation of measles virus is an essential tool in the laboratory surveillance of measles, especially in countries like Norway which are approaching the measles elimination goal. The investigation revealed that importation of measles resulted in subsequent transmission within Norway to non-vaccinated individuals, and twelve cases occurred in healthcare settings, involving both staff and children. The four cases detected among healthcare workers (HCWs) emphasised that the coverage of measles-mumps-rubella (MMR) vaccination among healthcare personnel needs to be improved and both primary and secondary vaccine failure was demonstrated in two fully immunised HCWs.

Molecular characterization of wild‐type measles viruses in Tamil Nadu, India, during 2005–2006: Relationship of genotype D8 strains from Tamil Nadu to global strains

Molecular characterization of measles viruses is a valuable tool for measuring the effectiveness of measles control and elimination programmes. WHO recommends that virological surveillance be conducted during all phases of measles control to document circulation of indigenous strains and trace future importation. This report describes the genetic characterization of wild type measles viruses from Tamil Nadu, India isolated between January 2005 and January 2006. In the study, 304 suspected measles cases (292 from 56 outbreaks and 12 sporadic cases) were investigated. Blood samples were collected from suspected measles outbreaks and 11 suspected sporadic cases and tested for the presence of measles and rubella specific IgM. Based on serological results, 53 outbreaks were confirmed as measles, 2 as a combination of measles and rubella, and 1 negative for both. Eight sporadic cases were confirmed as measles and one as rubella. Throat swab and urine samples were collected for virus isolation and 28 isolates were obtained. Sequencing and analysis showed that 3 isolates belonged to genotype D4 and 25 to genotype D8. Comparison of the genotype D8 sequences from Tamil Nadu with previously reported genotype D8 sequences from India and abroad showed six distinct clusters with Tamil Nadu strains forming two clusters. This study has established baseline molecular data and is the first report that describes genetic diversity of circulating measles strains in Tamil Nadu, a state in India. D8 has multiple lineages and this has been linked with importation of measles into the USA and UK.

Direct costs of a single case of refugee-imported measles in Kentucky

Refugees are highly vulnerable populations with limited access to health care services. The United States accepts 50,000-75,000 refugees for resettlement annually. Despite residing in camps and other locations where vaccine-preventable disease outbreaks, such as measles, occur frequently, refugees are not required to have any vaccinations before they arrive in the United States. We estimated the medical and public-health response costs of a case of measles imported into Kentucky by a refugee. The Kentucky Refugee Health Coordinator recorded the time and labor of local, state, and some federal personnel involved in caring for the refugee and implementing the public health response activities. Secondary sources were used to estimate the labor and medical care costs of the event. The total costs to conduct the response to the disease event were approximately $25,000. All costs were incurred by government, either public health department or federal, because refugee health costs are paid by the federal government and the event response costs are covered by the public health department. A potentially preventable case of measles that was imported into the United States cost approximately $25,000 for the public health response. To maintain the elimination of measles transmission in the United States, U.S.-bound refugees should be vaccinated overseas. A refugee vaccination program administered during the overseas health assessment has the potential to reduce the risk of importation of measles and other vaccine-preventable disease and would eliminate costs associated with public health response to imported cases and outbreaks.

The Americas: Paving the Road Toward Global Measles Eradication

The Region of the Americas set a goal of interrupting endemic measles virus transmission by the end of 2000. This decision was primarily based on rapid decreases in measles disease burden in pioneering countries that implemented Pan American Health Organization-recommended vaccination and surveillance strategies. Review of these strategies may inform measles elimination efforts in other regions. Results from the implementation of the measles elimination strategy in the Americas were compiled and analyzed over a 30-year period, which was divided into 4 phases: the early years of the Expanded Program on Immunization (1980-1986); the start-up phase for elimination (1987-1994); the elimination phase (1995-2002); and the postelimination phase (2003-2010). Factors that contributed to elimination and the challenges confronted during the postelimination phase are discussed. An analysis of vaccination strategies over time highlights the transition from monovalent measles vaccine to the incorporation of measles-mumps-rubella vaccine administered in the routine program. Regional vaccination coverage increased during the period 1987-2010, sustained at ≥90% since 1998. Measles elimination efforts led to the implementation of 157 national vaccination campaigns, vaccinating a total of 440 million persons. Endemic measles virus transmission was interrupted in 2002. After elimination, measles importations and associated outbreaks occurred. Measles incidence has remained at <1 case per 1 million population since 2002. The success of measles elimination strategies in the Americas suggests that global measles eradication is attainable.

Measles Importation Leads to Spike in U.S. Cases

Measles Importation Leads to Spike in U.S. Cases

Measles—United States, January 1–April 25, 2008

Measles is a highly contagious, acute viral illness that can lead to complications such as pneumonia, encephalitis, and death. As a result of high 2-dose measles vaccination coverage in the United States and improved control of measles in the World Health Organization's Region of the Americas, the United States declared measles elimination (defined as interruption of year-round endemic transmission) in 2000. Importations from other countries where measles remains endemic continue to occur, however, which can lead to clusters of measles cases in the United States. To update surveillance data on current measles outbreaks, CDC analyzed cases reported during January 4-April 2, 2015. A total of 159 cases were reported during this period. Over 80% of the cases occurred among persons who were unvaccinated or had unknown vaccination status. Four outbreaks have occurred, with one accounting for 70% of all measles cases this year. The continued risk for importation of measles into the United States and occurrence of measles cases and outbreaks in communities with high proportions of unvaccinated persons highlight the need for sustained, high vaccination coverage across the country.

An outbreak of measles in an ultra-orthodox Jewish community in Jerusalem, Israel, 2007 - an in-depth report

Measles elimination in Europe is hindered by recurrent outbreaks, typically in non-immunised specific sub-populations. In 2003 and 2004, two measles outbreaks occurred in Jewish ultra-orthodox communities in Jerusalem, Israel. In 2007, another measles outbreak emerged in Jerusalem. Epidemiological investigation and control activities were initiated. Three measles cases (15 years old, 22 years old and an infant; all unvaccinated) were diagnosed in Jerusalem in August 2007. All three belonged to Jewish ultra-orthodox communities in London, United Kingdom, and had had contact with patients in London. The epidemiological investigation did not reveal any connection between these cases other than their place of origin. The disease spread rapidly in extremely ultra-orthodox sub-groups in Jerusalem. Until 8 January 2008, 491 cases were reported. Most patients (70%) were young children (0-14 years old), 96% unimmunized. Frequently, all the children in a large family were infected; two thirds of the cases belonged to family clusters of more than two patients per family (in part due to non-compliance with post-exposure prophylaxis recommendations). The high age-specific incidence among infants 0-1-year- (408.5/100,000) and 1-4-year-olds (264.1/100,000) is a cause for concern. The hospitalisation rate was 15% (71/491), mainly due to fever, patients (26.7%) presented with pneumonitis or pneumonia and two patients presented with encephalitis. There have not been any deaths to date. The outbreak was apparently caused by measles importation into unprotected groups. Despite a high national immunisation coverage (94-95%), programmes to increase and maintain immunisation coverage are essential, with special focus on specific sub-populations.

Molecular characterization of measles virus circulating in the Indian Ocean Islands during 2005–2006 and in France in 2006

Despite the availability of safe and immunogenic vaccines, measles still causes significant morbidity and mortality especially in Africa. In this study, two measles outbreaks in the Indian Ocean Islands; Mayotte in 2005-2006 and Seychelles in 2006 were studied. Nasopharyngeal swabs, urine and/or blood samples were collected from patients with clinically diagnosed measles. Measles viruses were isolated in four cases from patients in Mayotte. Measles strains circulating in both outbreaks were determined to be genotype D4 when compared to the WHO reference strains. During this time, measles virus was isolated from patients in France and they were also found to belong to the same genotype. The viruses clustered into two distinct D4 subgroups; The Indian Ocean strains were similar to the Montreal-subgroup, whereas the French strains associated with the Johannesburg-subgroup. The Indian Ocean strains formed a homogeneous group. They shared four specific amino acids in the 3' region of the N gene and two amino acids in the H gene, which differed from other genotype D4 viruses. This suggests that the same measles lineage circulated in Mayotte and Seychelles. Sequence comparison of the French isolates with other measles strains showed that they were more closely related to strains circulating in Germany in 2005, which had their origin in Romania. This study provides the baseline for molecular epidemiology of measles virus in Mayotte and Seychelles. The knowledge of circulating measles virus will help in documenting measles elimination program. This report also highlights the fact that progress of measles elimination is blighted continually by the phenomenon of measles importation.

Implications of a 2005 Measles Outbreak in Indiana for Sustained Elimination of Measles in the United States

Measles was declared eliminated from the United States in 2000 but remains endemic worldwide. In 2005, a 17-year-old unvaccinated girl who was incubating measles returned from Romania, creating the largest documented outbreak of measles in the United States since 1996. We conducted a case-series investigation, molecular typing of viral isolates, surveys of rates of vaccination coverage, interviews regarding attitudes toward vaccination, and cost surveys. Approximately 500 persons attended a gathering with the index patient one day after her return home. Approximately 50 lacked evidence of measles immunity, of whom 16 (32 percent) acquired measles at the gathering. During the six weeks after the gathering, a total of 34 cases of measles were confirmed. Of the patients with confirmed measles, 94 percent were unvaccinated, 88 percent were less than 20 years of age, and 9 percent were hospitalized. Of the 28 patients who were 5 to 19 years of age, 71 percent were home-schooled. Vaccine failure occurred in two persons. The virus strain was genotype D4, which is endemic in Romania. Although containment measures began after 20 persons were already infectious, measles remained confined mostly to children whose parents had refused to have them vaccinated, primarily out of concern for adverse events from the vaccine. Seventy-one percent of patients were from four households. Levels of measles-vaccination coverage in Indiana were 92 percent for preschoolers and 98 percent for sixth graders. Estimated costs of containing the disease were at least 167,685 dollars, including 113,647 dollars at a hospital with an infected employee. This outbreak was caused by the importation of measles into a population of children whose parents had refused to have them vaccinated because of safety concerns about the vaccine. High vaccination levels in the surrounding community and low rates of vaccine failure averted an epidemic. Maintenance of high rates of vaccination coverage, including improved strategies of communication with persons who refuse vaccination, is necessary to prevent future outbreaks and sustain the elimination of measles in the United States.

Rapid diversification of measles virus genotypes circulating in Morocco during 2004–2005 epidemics

Measles virus strains circulating in six different regions in Morocco during 2004-2005 were analysed. They were genotyped using two different methods: the recently developed method based on real-time PCR amplification and melting curve analyses, and the conventional method based on nucleic acid sequencing and phylogenetic analysis of 456 nucleotides of the 3'-region of the nucleoprotein (N) gene sequence. Five genotypes (A, B3.2, C2, D7 and D8) were shown to be circulating during this period. Previous studies on measles virus genotypes in Morocco (1998-2003) showed that only the genotype C2 was present and was considered to be endemic. Sequence comparison of the 2004-2005 viruses with other measles strains suggests that measles strains belonging to genotype B3.2 were probably imported from West Africa, whereas those belonging to genotypes D7 and D8 were imported from Europe. These studies which identify the route of importation of measles are important for developing strategies for measles elimination in Morocco.

Measles vaccines and the potential for worldwide eradication of measles.

The annual number of reported measles cases in the United States has declined from between 3 million and 4 million in the prevaccine era to <100 cases in association with the highest recorded immunization rates in history. Because of continued importation of measles into the United States, young children who are not vaccinated appropriately may experience more than a 60-fold increase in risk of disease. Unsubstantiated claims suggesting an association between measles vaccine and neurologic disorders have led to reduced vaccine use and a resurgence of measles in countries where immunization rates have declined below the level needed to maintain herd immunity. To address the possibility of worldwide control of measles, efforts to ensure high immunization rates among people in both developed and developing countries must be sustained.

Disease and Death in the South African War: Changing Disease Patterns from Soldiers to Refugees

The involvement of civilians, Boer women, children, and blacks is increasingly integrated within the military history of the South African War. This article assesses the disease history of the war in this context, collating data on mortality from various sources for the first time. Over 60 per cent of total deaths during the war were among civilians, shared among all ethnic groups (Boer, black, and white), and measles was probably the largest killer. Disaggregation by individual refugee camp shows: the rapidity of the epidemics; the early mortality peaks by July 1901; the varied timing and severity of disease by camp; and the importance of measles in explaining the very high mortality rates. At first sight, the decline in overall mortality appears to coincide with the 'magical effects' of the British commissions so often cited by historians. However, individual camp mortality curves do not support this historical explanation. We emphasize the epidemiological dynamics of measles, as well as the effects of local camp conditions of overcrowding and malnutrition. Providing a less dashing picture, the South African War is best characterized by measles as well as typhoid. The war shows the crossing in importance of a nineteenth-century military disease history represented by typhoid, and a refugee-civilian disease history that extends to the end of the twentieth century.

Genotyping of measles virus in Canada: 1979-2002.

Genotyping is an important component of measles surveillance. In this study, we report the genotypes of 30 measles viruses from cases in Canada; 6 of these were collected between 1979 and 1996 and 24 were collected from 1997 through 2002. Many measles virus genotypes were found (C1, C2, D3, D4, D5, D6, D7, D8, E, and H1). These data indicate that the predominant measles virus genotypes detected from 1979 to 1997 in Canada are no longer commonly found. Since the implementation of a routine second dose of measles vaccine and catch-up campaigns in 1996-1997, the wide variety of measles virus genotypes found supports epidemiological data showing that importation of measles is the source of current measles cases in Canada.

International importation of measles virus--United States, 1993-2001.

To determine trends in international importations of measles, data from the National Notifiable Diseases Surveillance System were analyzed. Of the 2632 measles cases reported between 1993 and 2001, 449 cases (17%) were internationally imported. An additional 186 cases (7%) resulted from spread of measles virus from these imported cases, and 388 cases (15%) had virological evidence of importation. The number of imported cases averaged 50 per year (range, 26-79 cases). The proportion of cases imported increased from an average of 14% in 1993-1996 to an average of 35% in 1997-2001. Imported measles cases were acquired in 63 countries, with 6 countries (Japan, Germany, China, the Philippines, Italy, and the United Kingdom) accounting for 44% of all imported cases. Further reduction of measles in the United States requires international cooperation and improved global surveillance and control of measles.

Measles elimination in the United States.

In 1962, immediately preceding the licensure of the first measles vaccines in the United States, when measles was a nearly universal disease, Alexander Langmuir described the medical importance of measles to the country and put forth the challenge of measles eradication [1]. Although most patients recovered without permanent sequelae, the high number of cases each year made measles a significant cause of serious morbidity and mortality. Langmuir showed that 190% of Americans were infected with the measles virus by age 15 years [1]. This equated to roughly 1 birth cohort (4 million people) infected with measles each year. Not all cases were reported to the public health system; from 1956 to 1960, an average of 542,000 cases were reported annually. By the late 1950s, even before the introduction of measles vaccine, measles-related deaths and case fatality rates in the United States had decreased markedly, presumably as a result of improvement in health care and nutrition. From 1956 to 1960, an average of 450 measles-related deaths were reported each year (∼1 death/ 1000 reported cases), compared with an average of 5300 measles-related deaths during 1912‐1916 (26 deaths/ 1000 reported cases) [2]. Nevertheless, in the late 1950s, serious complications due to measles remained frequent and costly. As a result of measles virus infections, an average of 150,000 patients had respiratory complications and 4000 patients had encephalitis each year; the latter was associated with a high risk of neurological sequelae and death. These complications and others resulted in an estimated 48,000 persons with measles being hospitalized every year [3].

African-American children are at risk of a measles outbreak in an inner-city community of Chicago, 2000

Background: Since the measles resurgence of 1989–1991, which affected predominantly inner-city preschoolers, national vaccination rates have risen to record-high levels, but rates among inner-city, preschool-aged, African-American children lag behind national rates. The threat of measles importations from abroad exists and may be particularly important in large U.S. cities. To stop epidemic transmission, measles vaccination coverage should be at least 80%. Objective: To determine measles vaccination rates and predictors for having received a dose of measles-containing vaccine by age 19 to 35 months among children in an inner-city community of Chicago. Methods: We used a cross-sectional survey with probability proportional to size cluster sampling. Immunization histories from parent-held records and providers were combined to establish a complete vaccination history. Results: A total of 2545 households were contacted, and 170 included a resident child aged 12 to 35 months. Of these, 97% (N=165 children) agreed to participate. Immunization history from a parent or provider was not available for 20 children. Among children aged 19 to 35 months with available immunization histories, 74% received measles vaccine ( n=100); of these, 84% received the vaccine as recommended at ages 12 to 15 months. However, when including children without immunization histories, measles coverage levels among children aged 19 to 35 months were 64% (n=114). Among children with records, predictors for receipt of measles vaccine by age 19 to 35 months were possessing a hand-held immunization card (odds ratio [OR]=16.8; 95% confidence interval [CI]=4.2–67.1); utilizing a public health department provider for a usual source of care (OR=8.9; 95% CI=1.6–47.2); and being up-to-date for vaccines at 3 months of age (OR=5.0; 95% CI=1.8–14.1). Conclusions: Optimistically assuming that children without immunization histories are as well immunized as children with immunization histories, the measles vaccination rate among Englewood’s children aged 19 to 35 months is too low to maintain immunity (74%). Measles coverage levels lagged behind coverage reported in a national survey in Chicago (86%) and the nation as a whole (92%). Efforts to raise and sustain coverage should be undertaken.

Measles elimination: progress and challenges

The accelerating progress in reducing measles incidence and mortality in many parts of the world has led to calls for its global eradication during the next 10–15 years. Three regions have established goals of elimination of indigenous transmission of measles. The strategy used in the Americas of a mass ‘catchup’ campaign of children 9 months to 15 years of age, high coverage through routine vaccination of infants, intensive surveillance and follow-up campaigns to prevent excessive build-up of susceptibles has had great success in reducing measles transmission close to zero. However, while these developments are impressive, much remains to be done to reduce measles-associated mortality in western and central Africa, where less than half of children are currently receiving measles vaccine and half a million children die from measles each year. The obstacles to global measles eradication are perceived to be predominantly political and financial. There are also technical questions, however. These include the refinement of measles elimination strategies in the light of recent outbreaks in the Americas; the implications of the HIV epidemic for measles elimination, issues around injection safety, and concerns about the possibility that secondary vaccine failures will contribute in sustaining transmission in highly vaccinated populations. The global priorities are to improve measles control in low income countries, increase awareness among industrialized countries of the importance of measles, and conduct studies to answer the technical questions about measles elimination strategies.

The interruption of transmission of indigenous measles in the United States during 1993.

The United States has a goal to eliminate all indigenous cases of measles by the year 2000. Initial interruption of indigenous measles transmission would be expected during a period of very low measles incidence as occurred during late 1993. Indigenous measles cases (i.e. cases acquired in the United States and not traceable to any imported case) from 1993 were investigated to determine their source of infection. The probability of sustained undetected measles transmission between isolated indigenous cases was estimated. Of the 312 measles cases reported for 1993, only 25 (8%) occurred after September 19. Of these only 4 cases (16%) could be classified as indigenous. The estimated probability that any of these 4 cases resulted from indigenous measles transmission in theirs or any adjoining counties was 0.05 or less. Interruption of indigenous measles transmission appears to have occurred for the first time throughout the United States in 1993. This event provides strong support for the current national strategy for measles elimination. However, complete elimination of indigenous measles will require maintaining high population immunity to prevent spread from imported cases and attaining global measles control to prevent the importation of measles.

New genetic group of measles virus isolated in the People's Republic of China

Genetic and antigenic characterization of 14 wild-type measles viruses isolated from four provinces in the People's Republic of China during 1993 and 1994 was conducted. Sequence analyses of the hemagglutinin (H) and nucleoprotein (N) genes indicated that 13 of the 14 Chinese viruses comprised a previously undescribed genetic group. Viruses from this unique group were the most genetically diverse measles viruses described, so far. The Chinese viruses differed from other wild-type viruses by as much as 6.9% in the H gene and 7.0% in the N gene at the nucleotide level. One of the 14 viruses was a member of the same genetic group that contains the Edmonston strain. Antigenic analysis using monoclonal antibodies to the H protein did not detect significant differences in binding patterns between the Chinese viruses and other wild-type measles viruses. In addition, representative viruses from the unique Chinese group were neutralized by both human post-vaccination antiserum and mouse antiserum against the H protein of the Edmonston vaccine virus. Viruses closely related to these Chinese viruses were also associated with importations of measles into the United States during 1997 from Vietnam and Hong Kong suggesting that viruses from this new genetic group continue to circulate in China and possibly other parts of Asia.