Imported Measles Cases Research Articles

Investigation on an outbreak of measles caused by new virus (d11 genotype) imported from Myanmar

To study the relevant factors on an measles outbreak caused by imported new virus (d11 genotype) from Myanmar and to develop effective strategies and measures. On-site investigation on the outbreak was carried out. There were four townships (66%) in Menglian county reported 15 cases of measles, with 7 cases aged 6 months to 5 years old, 2 cases with the history of measles vaccination (MV). Another 8 cases were 21 to 49 year-olds but their histories on immunization were unclear. 14 of the measles cases with Myanmar citizenship came to China for treatment. They were aged 10 months to 13 years old, with only one case had ever received MV vaccination. For all the 29 cases, except for one case who did not adopt the sample case of Myanmar, the remaining 28 patients were positive for measles IgM antibodies. 6 cases of measles virus RNA were detected in the amplified sequence which showed genotype d11, and was considered Myanmar imported wild virus. 184 people received the MV inoculation, with a rate of 61.96% and the serum samples showed a measles IgG antibody positive rate of 87.50%. Manner MV emergency vaccination was carried out timely in that county so the measles outbreak was effectively controlled. Imported measles cases from foreign countries might lead to epidemic, indicating the difficulty and challenge in the elimination of measles in our province. Emergent vaccination of MV could interrupt the transmission of the disease. Our experience showed that MV was effective in the prevention of d11 genotypes measles infection in the area.

Measles Exportation From Japan to the United States, 1994 to 2006

Imported measles cases and outbreaks involving Japanese travelers have been reported from the United States and other countries. For the United States, Japan is the top country of origin. The aims of this study were to analyze measles exportation trends from Japan to the United States and to suggest recommendations for improving monitoring and control in both countries. Reviewing all exportation cases reported to the Centers for Disease Control and Prevention and sentinel measles activity data monitored by the Japanese Ministry of Health between January 1994 and December 2006 (observation period). A total of 63 cases were reported (median = 4 cases per year). Cases ranged in age from 9 months to 53 years (median = 17 y). Peaks occurred at 13 to 26 years and 12 to 35 months. Six cases were US citizens and 57 Japanese. Ten cases were reported in July and August, followed by eight in February and March. Twenty-seven cases were reported from Hawaii, followed by 15 from California and 6 from New York. Seven cases developed the secondary spread. Three of the cases had previously received one dose of measles vaccine, compared to 35 who were never immunized (25 cases unknown). During the observation period, measles activity exceeded the warning level in 157 weeks, with measles exportation occurring the subsequent week for 30 of these weeks. In comparison, during the 521 weeks in which measles activity was below the warning level, exportation of measles the following week was observed for 21 of those weeks (OR = 5.62, 95% CI = 3.12-10.2, p < 0.001). Trend of exported measles cases from Japan to the United States has corresponded with the measles activity trend in Japan. Most of the cases were unvaccinated. This international health problem should be solved by strong leadership of Japanese public health professionals.

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.

Evolution of measles elimination strategies in the United States.

There have been 3 efforts to eliminate measles from the United States since the introduction of measles vaccine in 1963. To date, 10 major lessons have been learned from elimination efforts. First, elimination requires very high vaccination-coverage levels by age 2 years. Second, school immunization requirements ensure high coverage rates among schoolchildren. Third, a second dose of measles vaccine is needed to achieve satisfactory levels of immunity. Fourth, school immunization requirements can also ensure delivery of a second dose. Fifth, coverage assessment is crucial. Sixth, measles surveillance is critical for developing, evaluating, and refining elimination strategies. Seventh, surveillance requires laboratory backup to confirm a diagnosis. Eighth, tracking measles virus genotypes is critical to determining if an endemic strain is circulating. Ninth, once endemic transmission has been interrupted, internationally imported measles cases will continue and will cause small outbreaks. Tenth, collaborative efforts with other countries are essential to reduce imported measles cases.

The largest outbreak of measles in the United States during 1999: imported measles and pockets of susceptibility.

The largest measles outbreak in the United States during 1999 was traced to a 34-year-old minister with an undocumented history of vaccination, infected while traveling outside the United States. Local health departments in the Central Virginia Health District performed an epidemiological and laboratory investigation that identified 14 additional confirmed cases of measles, including 2 in health care providers and 5 in congregation members. Eight cases (53%) occurred among adults aged 30-35 years and 7 (47%) among children aged 13 months to 8 years. Although no religious exemptions were cited, only 2 case patients had documented proof of vaccination. This outbreak demonstrates the potential for limited indigenous spread of measles that occurs when imported cases expose susceptible groups. Almost half of the imported measles cases in the United States occur in US residents returning from foreign travel. Vaccination is highly recommended for all overseas travelers who are without documented proof of adequate immunization or measles immunity.

Epidemiology of Measles—United States, 1998

Measles is a highly infectious, acute viral illness that can cause severe pneumonia, diarrhea, encephalitis, and death. To characterize the epidemiology of measles in the United States during 2001-2003, CDC analyzed data reported by state and local health departments. This report summarizes the results of that analysis, which indicated that no endemic measles virus is circulating in the United States; however, imported measles cases continue to occur and can result in limited indigenous transmission. Maintaining immunity through high vaccination coverage levels is essential to limit the spread of measles from imported cases and prevent measles from becoming endemic.

Trends in Importation of Measles to the United States, 1986-1994

To describe patterns among imported measles cases to the United States. Descriptive analysis of national case-based surveillance data on measles cases. United States in the period 1986 through 1994. All reported confirmed cases of measles. Demographic variables, immunization history, country of exposure, and reporting state. The number of reported imported cases of measles to the United States has dropped from an average of 99 cases annually in 1986 through 1988 and 190 cases in 1989 through 1991 to 61 cases in 1992 through 1994. Since 1990, the number of imported cases originating in Latin America declined by 98%, despite continued increase in the number of travelers to this region; cases from other regions remained relatively constant. This decrease paralleled the rapid decrease in measles incidence in the Western Hemisphere associated with national measles elimination programs. Most imported cases occurred among children, although 22% of cases occurred among young adults. Rates of measles cases per 1 million travelers are higher among non-US citizens than among US citizens. The sharp decline in importations into the United States from Latin America since 1991 provides evidence of the success of measles control efforts undertaken there. The decrease in imported cases has been associated with a decline in total measles cases in the United States. Sustained elimination of measles in the United States will require improved measles control in other countries in addition to a high level of population immunity.

Measles Elimination in the Americas

In February 1992, PAHO hosted an Informal Consultation of Measles Elimination in the Americas in Washington, D.C. to review past and current control and elimination efforts, to weigh the scientific and technical feasibility of eliminating measles from the Americas, and to suggest a role for PAHO to further the program. When the measles vaccine 1st appeared in the 1960s, coverage rose, the periods between epidemics increased, and the epidemics involved fewer numbers of people afflicted with measles. The Gambia began vaccinating all 5-year old children in 1967 and it had interrupted measles transmission between 1968-70. It stopped the strategy that achieved this and transmission levels increased. In the US, the Childhood Immunization Initiative begun in 1978 set out to eliminate indigenous transmission of measles by 1982. The US achieved 95% coverage of children entering school and measles incidence fell 99% Yet the US could not eliminate measles. Obstacles included imported measles cases, missed vaccination opportunities, shifting epidemiology of measles to 10-19 year old susceptibles, and high degrees of contagiousness. In 1988, Cuba began its campaign to eliminate indigenous measles transmission. By 1989, it may have achieved transmission interruption. In the last 3 years, authorities have identified only 3 imported cases. The English-speaking Caribbean began a program in 1988. It planned to strengthen routine delivery of measles vaccine to all health facilities and to vaccinate all 1-14 year old children regardless of vaccination status. The mass campaign started in May 1991. By September 1991, authorities had identified only 4 measles cases. Sao Paulo State, Brazil began its mass vaccination campaign (all 1-14 year old children) in 1987. Measles-related deaths fell 98% between 1987-90. The meeting participants believed the Americas could indeed be the 1st region to eliminate measles since it was the 1st to eliminate smallpox and is close to eliminating polio. They hoped PAHO would support present initiatives to eliminate measles in the Americas.

Imported Measles in the United States

In the period 1980-1981, two hundred nine imported measles cases were reported in the United States. These cases represent 1.3% of the total of 16,630 cases of measles reported to the Centers for Disease Control (CDC) during that period. An average of two imported measles cases were reported each week. The travelers with imported measles were United States citizens and foreign nationals who arrived from 47 different countries throughout the world. However, returning United States citizens have accounted for a rising proportion of imported measles cases. Approximately half (49.3%) of the imported cases were reported by four areas: California, New York State exclusive of New York City, New York City, and Florida. Seven measles outbreaks occurring following importations during the two-year period were identified. In addition to 114 imported measles cases reported to the CDC in 1981, 437 measles cases were reported to be caused directly or indirectly by those importations. The actual number of importassociated cases may have been considerably higher. Imported measles and associated cases together accounted for at least 17% (551/3,124) of reported measles cases in 1981. ( JAMA 1982;248:2129-2133)

Imported measles in the United States

In the period 1980-1981, two hundred nine imported measles cases were reported in the United States. These cases represent 1.3% of the total of 16,630 cases of measles reported to the Centers for Disease Control (CDC) during that period. An average of two imported measles cases were reported each week. The travelers with imported measles were United States citizens and foreign nationals who arrived from 47 different countries throughout the world. However, returning United States citizens have accounted for a rising proportion of imported measles cases. Approximately half (49.3%) of the imported cases were reported by four areas: California, New York State exclusive of New York City, New York City, and Florida. Seven measles outbreaks occurring following importations during the two-year period were identified. In addition to 114 imported measles cases reported to the CDC in 1981, 437 measles cases were reported to be caused directly or indirectly by those importations. The actual number of import-associated cases may have been considerably higher. Imported measles and associated cases together accounted for at least 17% (551/3,124) of reported measles cases in 1981.