Measles epidemiology and outbreak response immunization in a rural community in Peru.

Only limited data are available on the impact of measles outbreak response immunization (ORI) in developing countries. We conducted a community survey in Espindola, a rural border community in northern Peru, following a measles outbreak and subsequent ORI to study the epidemiology and impact of the outbreak and to evaluate the costs and benefits of measles ORI. During the outbreak, 150 of the 553 Espindola residents developed clinical cases of measles. Adults accounted for 44.0% of cases, and were frequently identified as primary cases. The attack rate among all susceptible people was 45.5% and was highest (61.2%) for the 16-20 year age group. Among adults, significant risk factors for developing measles included being aged 16-20 years (relative risk [RR] = 3.06, 95% CI = 2.08, 4.49) and being male (RR = 1.73, 95% CI = 1.11, 2.71). Among serologically confirmed cases, 60.7% developed diarrhoea and 32.1% pneumonia. The overall case-fatality rate was 3.3%, but reached 19.1% in the 0-23-month age group. Failure to reach children through either routine immunization or national campaigns made this community vulnerable to the severe and extensive impact of measles virus importation. The ORI campaign targeted non-measles case children aged 6 months to 15 years, regardless of their previous immunization status, and was effective in terminating this measles outbreak and in preventing morbidity, loss of livelihood and death despite the involvement of large numbers of adults in measles transmission. The last measles case occurred within 3 weeks of completing ORI. The ORI campaign, which would have cost approximately US$ 3000 in 1998, saved as many as 1155 person-days of work among 77 adults, prevented an estimated 87 cases of diarrhoea and 46 cases of pneumonia, and averted 5 deaths.     

马关县苗族村寨麻疹爆发的调查

目的了解云南省马关县苗族村寨2005年10月16日~11月12日麻疹爆发的原因。方法对麻疹疫情进行流行病学调查分析,收集患者急性期鼻咽拭子和尿标本,分离麻疹病毒;采集现症病例和未发病人群血清标本,用酶联免疫吸附试验检测抗体。结果119例麻疹分布于4个村。年龄最小的8月龄,最大32岁,0~13岁占84.87%。现症病人63.16%无麻疹减毒活疫苗(MV)免疫史,31.58%免疫史不详。疫区301名儿童MV接种率88.37%,疫苗效力88.79%,麻疹感染人群中62%有接触史。患者血清标本麻疹IgM抗体阳性率59.09%,未发病人群血清标本麻疹IgG抗体阳性率61.76%。分离到麻疹病毒4株,基因型为H1。结论马关县苗族村寨发生的经血清学和病毒学检测证实的麻疹疫情,由于卫生院报告疫情滞后,部分村寨存在免疫空白,MV接种不落实导致爆发。麻疹感染者作为传染源应引起重视。     

连云港市2008~2009年麻疹暴发流行病学调查

[目的]了解连云港市麻疹暴发的流行病学特征,为制订麻疹防控策略提供科学依据。[方法]采用描述性流行病学方法进行麻疹疫情分析,血清学检验方法进行麻疹病例的实验室诊断,对麻疹高发村开展麻疹疫苗效力调查。[结果]2008年9月1日～2009年7月1日间连云港市局部地区发生了麻疹暴发流行,病例数为1234例,主要集中在3个县:灌云县(40.94/10万)、灌南县(44.15/10万)、赣榆县(24.34/10万)。在0～5岁儿童发病为多,占1234例麻疹病例的71.39%,其中8～24月龄婴幼儿发病占0～5岁组病例的69.92%。实验室诊断病例占91.65%;麻疹疫苗效力:下口村0～60月龄儿童为56.52%、元邦村为75.95%,平均为64.29%;麻疹疫苗调查平均接种率为58.33%。[结论]部分适龄儿童的漏种或未及时接种麻疹疫苗是连云港市3个县2008年9月～2009年7月间麻疹暴发流行的主要原因,因此应提高适龄儿童麻疹接种的及时性和接种率,确保2012年控制和消除麻疹目标的实现。     

Measles outbreaks in the Mozambican refugee camps in Malawi: the continued need for an effective vaccine

Between November 1988 and January 1989, measles outbreaks occurred in 11 Mozambican refugee camps in Malawi with five camps principally affected. A total of 1214 cases were reported. Despite the reduction of the age of measles vaccination to six months in 1987, attack rates were highest in children aged 6-9 months (10-26%); rates were also high in the 0-5 month age group (3-21%). The case-fatality rate was high among children less than five years old (15-21%). Children were being inappropriately vaccinated, either being vaccinated at less than six months of age (2-29%) or failing to receive a second dose if vaccinated at six months (0-25%). With vaccine coverage between 66-87%, vaccine efficacy in children less than five years old was estimated to be more than 90% in the camps principally affected. Reduction of the age of vaccination leads to logistical problems in vaccine delivery in refugee situations. These outbreaks again indicate the need to improve vaccine coverage with the existing Schwarz vaccine, and also highlight the urgent need for an effective single dose measles vaccine for children less than nine months of age.     

浙江省一起由免疫接种空白导致的流动人口麻疹暴发

目的 为核实浙江省某村1名麻疹确诊患儿家长报告同村有多名发热、出疹病例,并调查暴发原因.方法 疑似病例定义为2010年6月1日至8月3日,该村及其所在街道和周围邻村居民中出现发热伴出疹症状者;确诊病例为疑似病例中血清麻疹IgM抗体阳性者.在全村范围开展逐户搜索,通过中国疾病预防控制信息系统搜索该村所在街道及相邻村的麻疹报告病例.对全村8月龄至14岁流动儿童开展回顾性队列研究.结果 该村共发现19例麻疹病例(17例确诊和2例疑似),均为流动人口,罹患率以1～2岁组为最高(13%).首发病例6月4日抵该村后发病,在非法私人诊所就医,但未向卫生部门报告疫情,卫生部门通过患儿家长报告识别暴发时,疫情已持续1个月.315名8月龄至14岁流动儿童中,麻疹疫苗接种率为81%.无麻疹疫苗接种史的61名流动儿童中,16名有明确病例接触史者发病风险(88%,14/16)高于45名无病例接触史者(4.4%,2/45)(Fisher精确概率法,RR=20,95%CI:5.7～94).结论 该村流动儿童麻疹疫苗接种率低,非法私人诊所不按规定对病例进行报告、隔离和医疗诊治,是导致此次疫情暴发的主要原因.     

Practical Observations from an Epidemiological Investigation of a Measles Outbreak in a District of India

Background:

Measles is a major cause of childhood morbidity and mortality, accounting for nearly half of the morbidity associated with global vaccine preventable diseases. Regular outbreaks of Measles are reported in India, of which only a few are investigated. This study was conducted in the Shivpuri District of Madhya Pradesh (India) to investigate and asses various epidemiological factors associated with measles outbreak.

Materials and Methods:

A cross-sectional study was carried out in 30 randomly selected sub-centers in 8 blocks of the Shivpuri District of Madhya Pradesh, covering 212 villages, selected by cluster sampling. The villages, which had reported measles cases, were extensively investigated by the field teams through extensive house-to-house surveys during 12-19 May 2004.

Results:

A total of 1204 cases with 14 deaths were reported with an attack rate of 6.2% and a case fatality rate of 1.2%. In this study, 17.7% of the cases reported post-measles complications with diarrhea as the most common post measles complication. The routine measles vaccine and Vitamin A supplementation in the area was also less than 30%.

Conclusions:

The majority of the cases had occurred in the unvaccinated children and in under 5 year old population. There are repeated outbreaks and a long delay in reporting of the cases. The occurrence of cases, in a reasonable proportion of the vaccinated population, points toward the fact that there is a possibility of a vaccine failure in older children. This study calls for an improved surveillance system, an improvement in the cold chain, and enhancements for measles vaccination if India is to achieve the goal of measles elimination.     

A low-cost, community-based measles outbreak investigation with follow-up action.

An outbreak of measles in Kampala, Uganda, in 1990 raised concern about the effectiveness of the measles vaccine that was used. The Uganda EPI programme and the medical office of the Kampala City Council therefore conducted a community-based investigation, with door-to-door interviews in two selected communities. They revealed 68 measles cases ranging in age from 5 months to 12 years; the highest age-specific attack rate (32%) was found in children aged 12 to 23 months. BCG immunization coverage was high (85%), but measles immunization coverage was moderate (48%). One community, served by a mobile clinic, presented a vaccine efficacy of only 55%. Responses by mothers revealed that many had failed to have their children completely immunized because of a lack of information, and not because of difficulties in access to the service. In a follow-up, community leaders initiated monthly checking of immunization cards of both children and mothers. The low vaccine efficacy found in one of the communities resulted in a thorough assessment of the city's cold chain. This community-based approach proved to be cost-effective and practical for identifying the obstacles to effective immunization delivery.     

The unchanging epidemiology and toll of measles in Burma

An evaluation of the public health importance of measles in Burma was carried out in 1983 to formulate recommendations regarding the feasibility of incorporating measles vaccine into the country's Expanded Program on Immunization (EPI). A review of available medical, serological, and epidemiological data as well as a sample study of childhood deaths indicated measles is a major killer of infants and young children in Burma. Since 1978, there have been over 20,000 cases of measles per year, and almost all children are infected with the measles virus by age 10 years. The clinical attack rate for measles is highest during the 2nd year of life. During the measles season, this virus accounts for 20% of all pediatric admissions and places an acute strain on the hospital system. Respiratory complications are noted in 50-90% of all measles admissions, while gastrointestinal complications range from 5-25%. The case-fatality rate of hospitalized measles cases averages 8.2%. Measles accounted for 87 (35%) of 280 childhood deaths occurring in selected townships in Rangoon in 1982-83, and less than 20% of these children had been hospitalized before death. Taking into account all available survey and study data, the overall case-fatality rate for measles in Burma can be conservatively estimated at 1-2%. Since about 1 million cases of measles occur each year, 10,000-20,000 measles deaths/year can be expected. It is concluded that measles' heavy toll in terms of child deaths will not change until measles' vaccine is routinely provided to all infants and young children. The use of measles vaccine on a wide scale is justified not only by morbidity and mortality considerations, but by the burden this disese places on hospital and outpatient resources.     

Measles surveillance--United States, 1991.

A total of 9,643 measles cases was reported from the United States in 1991, a 65.3% decrease from the 27,786 cases reported in 1990. The overall incidence of measles was 3.9 cases per 100,000 population. The highest age-specific incidence was among children < 12 months of age (46.9/100,000) and 1-4 years of age (19.6/100,000). Incidence rates among American Indians, Hispanic, and black children < 5 years of age were 19, 6, and 4 times that for non-Hispanic white children, respectively. More than 61% of all cases were reported from seven large outbreaks, which involved predominantly unvaccinated preschool-age children in large urban areas. Although reported measles cases decreased in 1991 compared with 1989-1990, only a sustained effort to provide age-appropriate vaccination will prevent another resurgence of measles.     

Epidemiology of measles in Taiwan: dynamics of transmission and timeliness of reporting during an epidemic in 1988-9.

We analysed nation-wide reported measles cases during the 1988-9 epidemic and found that longer duration and wider spread were two major characteristics of the outbreak. All the 22 county/city index cases were reported with a delay of > 4 days and 64% were aged 5-14 years. This epidemic occurred mainly among 5-14-year-old school-children (59%), infants under 1 year (19%), and pre-school children (18%). The overall attack rate was 0.63 cases per 10,000 population, with the highest attack rate (7.4 cases per 10,000 population) occurring in infants. Among 280 confirmed cases < 15 months of age, 9-month-old infants (42 cases) had a higher risk of measles and peaked at 10 months (49 cases). This epidemic started in March 1988 among 5-9-year-old children in the northern suburban area, then spread to Taipei City and neighbouring counties or cities. It continued to spread from the northern to southern and western areas during the summer vacation and New Year holidays. Multiple logistic regression analysis showed that the delay of measles reporting was strongly associated with the cases infected early in the epidemic (OR = 6.9, P < 0.001) and reported from teaching hospitals (OR = 2.6, P < 0.001). The reappearance of high attack rates among 5-9-year-old children in the 1985 and 1988-9 measles epidemics in Taiwan indicated the persistence of pockets of susceptible individuals even after mass immunization.     

2010年玉溪市华宁县人群麻疹抗体水平调查

目的了解华宁县人群实施麻疹疫苗接种情况及血清抗体水平,为2012年按期实现消除麻疹提供依据。方法采用分层和整群抽样(PPS)方法,在华宁县范围内随机抽取3个乡镇,每个乡镇抽3个行政村,每个村按8个年龄组(1岁、1岁～、3岁～、5岁～、7岁～、11岁～、15岁～、≥20岁)进行,每个年龄组调查5或6人,共调查382人。结果调查的382人中麻疹疫苗接种率(≥1针次)为72.51%,抗体阳性率为95.03%;3个乡镇的人群麻疹疫苗接种率、抗体阳性率差异均有统计学意义(P0.05);各年龄组间麻疹疫苗接种率、抗体阳性率差异有统计学意义(P0.01),其中1岁人群的麻疹疫苗接种率、抗体阳性率均较低,分别为44.44%、77.78%;性别间麻疹疫苗接种率、抗体阳性率差异有统计学意义(P0.05),男性显著高于女性。结论华宁县人群麻疹抗体阳性率较高,能有效控制输入性病例引起的流行,对有效控制麻疹取得了较好的效果。     

Measles control in Maputo, Mozambique, using a single dose of Schwarz vaccine at age 9 months.

In Maputo city, immunization is available at government health facilities, all contacts being used to vaccinate children. Door-to-door mobilization is conducted to identify eligible children and refer them for immunization. Card-documented measles vaccine coverage, estimated by community surveys, rose from 48% in 1982 to 86% in 1986 and 92% in 1992. The median age at measles vaccination was 10.2 months in 1986 and 9.2 months in 1992. The reported measles incidence rates per 100,000 population fell by 92% from 569 in 1977-78 (pre-vaccination) to 44 in 1990-92, and the reported inpatient measles mortality fell from 19.8 to 0.7 per 100,000. Among children whose age at measles onset was known, the proportion of reported measles cases in children under 9 months of age fell from 2162 (20.3% of 10,636 cases) in 1982-85 to 1695 (17.8% of 9501 cases) in 1986-92. The proportion of cases in children aged > or = 5 years increased from 15.2% to 32.8% in the corresponding periods. The global goals for measles control can be achieved by a single dose of Schwarz vaccine at 9 months of age.     

A persistent outbreak of measles despite appropriate prevention and control measures

From January 4 to May 13, 1985, an outbreak of 137 cases of measles occurred in Montana and persisted for 12 generations of spread. A total of 114 cases occurred on the Blackfeet Indian reservation in northwest Montana. Of the 137 cases, 82 (59.9%) were in school-aged children (aged 5-19 years). Of the 114 cases on the reservation, 108 (94.7%) were classified as programmatically nonpreventable. A total of 64 (82.1%) of the 78 patients on the reservation who were born after 1956 and were above the recommended age at vaccination had a history of adequate measles vaccination. Additionally, an audit of immunization records at the schools in Browning, Montana, where most of the cases occurred, showed that 98.7% of students were appropriately vaccinated. A retrospective cohort study in the Browning schools failed to identify age at vaccination or time since vaccination as significant risk factors for vaccine failure. Overall vaccine efficacy was 96.9% (95% confidence interval = 89.5-98.2%). None of 80 Browning students who were vaccinated at less than 12 months of age and revaccinated at 15 months of age or older became infected. A case-control study showed a significant association between attendance at Browning basketball games and infection early in the outbreak. This outbreak suggests that measles transmission may persist in some settings despite appropriate implementation of the current measles elimination strategy.     

Priorities in global measles control: report of an outbreak in N'Djamena, Chad.

In N''Djamena, capital of Chad, measles vaccination coverage of 12-23-month-old children fell from 61% in 1990 to 15% in 1993. A community survey of measles after an outbreak in 1993 showed that among children < 5 years of age, the mean monthly attack rate was 37 per 1,000 (95% CI, 32-43) and the mean case fatality rate was 7.4%. Measles incidence was highest (77/1,000/month) in children aged 9-11 months and fell among children > 3 years of age. Incidence rates were high (56/1,000/month) among 6-8-month-old children, but only 3 deaths occurred in this age group. Measles vaccine efficacy, estimated by comparing attack rates in unvaccinated and vaccinated children, was 71% (95% CI, 59-80%). Extrapolation of the results to the city population indicated that an estimated 19,000 cases and > 1,000 measles-associated deaths occurred in 1993. This preventable morbidity and mortality, in a city where coverage was formerly among the highest in Africa, shows the need for sustained global commitment to preventive health care.     

School-based measles outbreaks: correlation of age at immunization with risk of disease.

During the Spring of 1978, students with a history of previous measles vaccination accounted for over three-forths of 203 cases of measles in a metropolitan county. Seventy cases occurred in two schools where 99% of the students were vaccinated. We analyzed countywide data to determine past patterns of measles vaccination, including outbreak control and vaccination update clinics. We also examined records of children from the two schools to assess the relationship between disease incidence and age at vaccination. When susceptibility was determined by trained health workers rather than by parents, fewer doses of measles vaccine were estimated to be needed. The majority of cases occurred among children 5 to 9 years old. Attack rates were higher for children vaccinated at 12 months of age or younger than for those vaccinated at 13 months of age or older. There were no significant differences in attack rates among children vaccinated at 13 months of age or older. These findings support recommendations for delaying routine measles vaccination until after 12 months of age and suggest that, during outbreaks, all children vaccinated prior to 13 months of age be revaccinated.     

Measles in Vietnamese refugee children in Hong Kong.

From September 1991-January 1992, there was a measles epidemic in an established refugee camp for 7000 Vietnamese 'Boat People' living in Hong Kong. This 16 week outbreak occurred against a backdrop of poor uptake of measles vaccination and overcrowded living conditions. Two hundred and sixty-two children were affected (155 boys, 107 girls); 235 children (89.7 %) were < 2 years old, age range 5-39 months. Children age 6-11 months had the highest crude attack rate (AR) of 54.3%. The highest age specific crude AR was 83.8% in children aged 14 months. Measles complications affected 234 (89.3%) children. Sixty-six children (25.2%) were admitted to hospital. There were two deaths from pneumonia, giving a case fatality rate of 0.76%. Measles control in refugee camps continues to be a public health challenge.     

浙江省1999年麻疹暴发疫情特征分析

浙江省 1999年麻疹监测系统报告 10起麻疹暴发疫情 ,发病 475例 ,无死亡。农村和学校为主要发生地 ;最高罹患率171 6 0‰ ,同时存在城区流动人口聚集地的麻疹暴发 ,但是发病强度偏低 ;发病时间主要分布在 1～ 6月和 10月 ;暴发病例中有明确麻疹疫苗 (MV)接种史的占 13 1% ,无MV接种史的占 2 8 2 % ,MV接种史不详的占 5 8 7% ;<14岁儿童病例数占总病例数的91 1%。对于学校和城区型暴发 ,应急免疫措施效果相对较好。建议在切实提高常规免疫接种率的同时 ,对持续有麻疹暴发和计划免疫工作薄弱地区采取MV的强化免疫     

A school-based measles outbreak: the effect of a selective revaccination policy and risk factors for vaccine failure

Persons who received measles vaccine between 12 and 14 months of age have been found to be at increased risk of measles compared with those vaccinated at greater than or equal to 15 months of age. Because of this, in 1987 the Immunization Practices Advisory Committee of the US Public Health Service recommended that, during measles outbreaks, revaccination of persons vaccinated at 12-14 months of age be considered. During a school-based outbreak in New Mexico in 1987, the authors evaluated the effect of a mandatory revaccination policy in affected schools. Before the effect of revaccination, the overall attack rate in persons vaccinated at greater than or equal to 12 months of age was 4.1 cases/1,000 students; afterward, the risk was significantly reduced by 73%, to 1.1/1,000 students. The attack rate among students targeted for revaccination declined 100%, compared with 41% among those not revaccinated. Overall, attack rates were significantly lower in schools conducting revaccination early compared with schools holding later revaccination. In a retrospective cohort study of single-dose vaccines in one school, age at vaccination was not associated with risk of disease; however, persons vaccinated greater than or equal to 10 years before the outbreak were at increased risk, independently of age at vaccination. Revaccination of persons whose most recent vaccination was between 12 and 14 months of age appeared to control transmission in this outbreak. Further studies are needed to confirm these observations and to evaluate the effect of other revaccination efforts during outbreaks.     

甘肃省2000——2008年麻疹流行病学特征分析

目的了解甘肃省2000—2008年麻疹流行病学特征,为消除麻疹工作提供科学依据。方法对2000—2008年麻疹发病情况进行描述流行病学分析。结果甘肃省2000—2008年平均发病率为7.96/10万。发病地区性差异显著,发病数东部、中部地区高于西部地区。发病以小年龄组儿童为主,15岁以下儿童发病数占发病总数的75.33%,近年来0～岁组和≥15岁组发病比例上升明显。无免疫史的占26.84%,接种1剂次的占19.04%,接种2剂次及以上的占10.43%,免疫史不详的占43.69%。每年3～5月为麻疹发病高峰。发病呈散发和局部暴发并存的状态。结论甘肃省麻疹发病有周期性规律,儿童麻疹疫苗接种率低,易感人群积累是发病的主要原因。小月龄儿童和≥15岁成人发病比例增加给消除麻疹工作带来新的挑战。应进一步加强麻疹疫苗常规免疫,并且适时开展麻疹疫苗的强化免疫,加强疫情监测,控制麻疹暴发。     

Measles vaccine effectiveness in Central Australian Aboriginal children vaccinated at or after eight months of age

An outbreak of measles in central Australia in 1994 provided the first opportunity to evaluate the effectiveness of the measles vaccine given to Aboriginal children at nine months of age since 1984. Children eligible for the study that was conducted in one community in the region were aged between nine months and 10 years. Eight of the 109 eligible children developed measles. The only unvaccinated child also developed measles. Vaccination failures occurred in 7.8% (6/77) of children vaccinated between eight and 11 months of age and in 3.2% (1/ 31) vaccinated after 11 months of age. Overall vaccine effectiveness was 93.5%. The level of vaccine uptake in central Australia is high and the last region-wide outbreak before 1994 occurred in 1981-82. If the age of vaccination against measles is to be determined by the average age of infection; the age of vaccination should now be raised to 12 months of age; this is the age at which Aboriginal children in all other states and all children in Australia are vaccinated.