Assessment of measles incidence, measles-related complications and hospitalisations during an outbreak in a southern Italian region

Spotlight on measles in Italy: why outbreaks of a vaccine-preventable infection continue in the 21st century

Measles is a serious infectious disease that can lead to significant morbidity and mortality. Remarkable progress has been made through measles vaccination in reducing the number of people dying from measles. In the last years, concerns about the safety of vaccines have led to decline in immunization coverage rates and new outbreaks of measles in many European countries, including Italy. We believe that it is important to reinforce the message that measles vaccine is safe and highly effective through appropriate information campaigns and public awareness.

Impact of measles national vaccination coverage on burden of measles across 29 Member States of the European Union and European Economic Area, 2006-2011

BACKGROUND

Challenges in reaching good vaccination coverage against measles emerged in several European Union/European Economic Area Member States (EU/EEA MS) leading to progressive accumulation of susceptible individuals and outbreaks. The Burden of Communicable Diseases in Europe (BCoDE) project developed a methodology for measuring the burden of communicable diseases expressed in Disability-Adjusted Life Years (DALYs) in the EU/EEA MS. The aim of this study was to compare national vaccination coverage and burden of measles across EU/EEA MS.

METHODS

Country-specific data on measles national vaccination coverage 2006-2011 from 29 EU/EEA MS (MCV1) were retrieved from Centralized Information System for Infectious Diseases (CISID). DALYs were calculated for each country separately using a disease progression model with a single input parameter (annual measles incidence, adjusted for under-estimation). A software application was used to compute estimated DALYs according to country-specific and year-specific population age-distributions (data retrieved from Eurostat). Log-linear mixed-effect regression modeling approach was used to investigate a linear relation between natural logarithm-transformed DALYs and coverage.

RESULTS

The reported annual vaccination coverage ranged from 72.6% to 100%. The estimated national annual burden ranged from 0 to 30.6 DALYs/100,000. Adjusting for year, there was a significant negative relationship between coverage and burden. For a given country there was a decrease in log-transformed DALYs/100,000 of 0.025 (95% confidence interval: -0.047 to -0.003) for every percentage increase in vaccination coverage. The largest effect of calendar time on estimated burden of measles was observed for the year 2011, the smallest was for the year 2007.

CONCLUSIONS

This study shows that the degree of success of national measles vaccination programs, when measured by the coverage obtained, is significantly associated with overall impact of measles across EU/EEA MS. In EU/EEA MS each percentage point increase in national vaccination coverage seems to lead to early significant reduction of overall burden of measles.

Feasibility and effectiveness of a population-based newborn hearing screening in an economically deprived region of Italy

AIM

To describe the effectiveness of a population-based newborn hearing screening program in an economically deprived region of southern Italy.

METHODS

A screening protocol was proposed for all newborns of the Campania region, starting on January, 2007. For infants identified with hearing loss, information on degree and type of hearing loss and presence of risk factors was collected.

RESULTS

The infants born in the 3-year study period were 182,188. Among them, 146,026 (80%) were tested with OAE. Sensorineural hearing loss ≥40dBnHL was established for 159 infants (1.1×1000). Among the NICU and WIN infants, the rate of hearing loss was respectively 9×1000 and 0.67×1000. Follow-up information was available for 111 children (70%), as 48 (30%) got care in other regions or health facilities. Most infants were fitted hearing aids by 1 month after diagnosis and 15 children (13.5%) received a cochlear implant at a mean age of 25 months (SD 10).

CONCLUSIONS

Even in a setting of population poverty, a universal newborn screening program can deliver satisfactory outcomes. The coverage and the tracking system of the program need to be improved, as well as the cooperation between public and private health services.

Epidemiology of two large measles virus outbreaks in Catalonia: what a difference the month of administration of the first dose of vaccine makes

Measles cases in the European Region have been increasing in the last decade; this illustrates the challenge of what we are now encountering in the form of pediatric preventable diseases. In Catalonia, autochthonous measles was declared eliminated in the year 2000 as the result of high measles-mumps-rubella vaccine (MMR) coverage for first and second dose (15 mo and 4 y) since the mid-1990s. From then on, sporadic imported cases and small outbreaks appeared, until in 2006-2007 a large measles outbreak affecting mostly unvaccinated toddlers hit the Barcelona Health Region. Consequently, in January 2008, first dose administration of MMR was lowered from 15 to 12 mo of age. A new honeymoon period went by until the end of 2010, when several importations of cases triggered new sustained transmission of different wild measles virus genotypes, but this time striking young adults. The aim of this study is to show the effect of a change in MMR vaccination schedule policy, and the difference in age incidence and hospitalization rates of affected individuals between both outbreaks.   Epidemiologic data were obtained by case interviews and review of medical records. Samples for virological confirmation and genotyping of cases were collected as established in the Measles Elimination plan guidelines. Incidence rate (IR), rate ratio (RR) and their 95% CI and hospitalization rate (HR) by age group were determined. Statistic z was used for comparing proportions. Total number of confirmed cases was 305 in the 2010 outbreak and 381 in the 2006-2007 outbreak; mean age 20 y (SD 14.8 y; 3 mo to 51 y) vs. 15 mo (SD 13.1 y; 1 mo to 50 y). Highest proportion of cases was set in ≥ 25 y (47%) vs. 24.2% in 2006 (p < 0.001). Differences in IR for ≤ 15 mo (49/100,000 vs. 278.2/100,000; RR: 3,9; 95%CI 2,9-5.4) and in overall HR 29.8% vs. 15.7% were all statistically significant (p < 0.001). The change of the month of age for the administration of the first MMR dose proved successful to protect infants. Yet, given the current epidemiological situation, continued awareness and efforts to reach young adult population, especially those at high risk of infection and transmission such as healthcare workers and travelers, are needed to stop the spread of the virus when importations occur.

Molecular epidemiology of measles virus in Italy, 2002-2007

Background

The European Regional Office of the World Health Organization (WHO/Europe) developed a strategic approach to halt the indigenous transmission of measles in its 53 Member States by 2015. In view of the goal of measles elimination, it is of great importance to assess the circulation of wild-type measles virus (MV). Genetic analysis is indispensable to understand the epidemiology of measles.

Methods

Urine and saliva samples were collected between May 2002 and December 2007, in order to find the origins and routes of wild type measles virus circulation. RT-PCR was performed on a total of 414 clinical samples of patients from different Italian regions. The results confirmed the genome presence in 199 samples, out of which 179 were sequenced. The sequences were genotyped by comparing the fragment coding for the carboxyl terminus of the nucleoprotein (450 nucleotides) with that one of the WHO reference strains.

Results

From the year 2002 to the year 2007 phylogenetic analysis of measles sequences showed a predominant circulation of the D7 genotype in the Italian territory for the years 2002–2004. This genotype was replaced by D4 and B3 genotypes in the biennium 2006–2007. During the same period C2, A, D5 and D8 genotypes were also detected.

Conclusions

Genetic characterization of wild-type MV provides a means to study the transmission pathways of the virus, and is an essential component of laboratory-based surveillance. Knowledge of currently circulating measles virus genotype in Italy will help in monitoring the success of the measles elimination programme and will contribute to evaluate the effectiveness of future vaccination campaigns.

Measles outbreak in Europe: susceptibility of infants too young to be immunized

As women vaccinated against measles transfer low amounts of antibodies, an increasing number of infants lack early protection through maternal antibodies until being immunised themselves. This paper reviews the literature on disease burden of measles in the population too young to be immunized according to the respective national recommendations during recent outbreaks in EU and EEA/EFTA countries. In addition, specific control strategies adopted to protect this young population are reviewed. Pubmed, Unbound Medline, Web of Knowledge and the Eurosurveillance database were searched using MESH terms: measles and epidemiology, measles and infants, prevalence of measles, measles and outbreaks and measles and epidemic. Additionally, data from Euvac.net and ECDC were consulted. Databases were searched from January 2001 to September 2011. Fifty-three papers were included in the analysis. The percentage of all measles cases during outbreaks affecting young infants ranged from 0.25% to 83.0%. Specific control strategies were adopted: e.g. administration of the first or second vaccine dose earlier than recommended. Infants younger than 12 months are often involved in measles outbreaks, and advancing the first vaccine dose could reduce the burden of disease. However, immunization before 9 months of age is not systematically recommended because of dysmature humoral immune responses of infants. High coverage and timely administration of the recommended series of vaccines are the most important measures to decrease measles incidence and measles circulation and protect vulnerable infants from infection.

Trend of hospital utilization for encephalitis

Encephalitis generally results in a serious illness requiring hospitalization. The aim of this study was to describe the epidemiology of hospitalization for encephalitis in Italy, taking into account the geographical distribution, aetiology, seasonality and evolution of hospitalization rates over recent years. The mean hospitalization rate was 5·88/100 000. For most of these hospitalizations (n=13 119, 55·6%), no specific cause of encephalitis was reported. The most common aetiological category was 'viral', which accounted for 40·1% (n=4205) of such hospitalizations (rate 1·05/100 000). Within this category, herpes virus was the leading causative agent (n=1579, 0·39/100 000). This report highlights a significant increase of 'viral encephalitis not otherwise specified' (ICD-9 code 049·9) vs. a reduction of all other causes. A seasonal pattern was noted in people aged ≥65 years in this group. Specific surveillance of encephalitis without known origin should be reinforced in order to identify the potential role of emerging pathogens and to design preventive interventions.

Measles-related hospitalizations and complications in Japan, 2007-2008

OBJECTIVE

In the present study we aim to describe the clinical features and related complications of severe measles requiring hospitalization in Japan in 2007 and 2008.

METHODS

We extracted the records of patients diagnosed with measles between July and December in 2007 and 2008 from the Diagnosis Procedure Combination (DPC) inpatient database and the verified age distribution of patients with measles requiring hospitalization and the rate of measles-related complications. We also examined the rate of measles patients who were pregnant or had malignancies.

RESULTS

We identified 1,037 inpatients in 377 hospitals; 879 in 2007 and 158 in 2008. Overall, 554 (53.4%) were male. Patient age distribution showed two peaks; ≤4 years (21%) and 15-29 years (45%). Ninety (8.7%) patients had pneumonia, 22 (2.1%) had encephalitis, 7 (0.7%) had intestinal complications, 7 (0.7%) had conjunctivitis, 6 (0.6%) had meningitis, and 4 (0.4%) had otitis media. Patients aged ≤14 years were significantly more likely to have pneumonia (16.4%; p<0.001). The rate of encephalitis was relatively low in patients aged ≤14 years (0.9%) compared with those aged 15-29 years (3.0%) and those aged ≥30 years (2.0%); the difference was not statistically significant (p=0.141). Of 31 pregnant women, 10 had spontaneous abortion or stillbirth. Twenty-eight patients had malignancies.

CONCLUSION

The present study adds important information to our knowledge of the clinical features of severe measles. Follow-up monitoring of the trends of this distressing disease using the DPC database will be essential.

[Prevention of respiratory tract diseases]

There are multiple possibilities for pulmonary or bronchial damage and their number exceeds that for the other organ systems dealt with in this issue. This multiplicity of diseases which are at least in part attributable to exogenous damage gives rise to manifold approaches to prevention. This overview does not claim to be complete. It is however intended to clarify the possibilities that exist for the prevention of pulmonary diseases. In addition, it intends to show that effective primary and occasionally secondary and tertiary prevention is inadequately utilized in pulmonology or not even used at all. Against the background that individual preventive measures in pulmonology are considerably more successful than curative measures, also from a health economics point of view, various options for successful prevention are described. The great need for studies on the effectiveness of preventive strategies is also addressed.

Kinetics of decline of maternal measles virus-neutralizing antibodies in sera of infants in France in 2006

The optimal age for measles vaccination is an important health issue, since maternal antibodies may neutralize the vaccine antigen before a specific immune response develops, while delaying vaccination may increase the risk of complicated diseases in infants. However, measles vaccination impacts the duration of protection afforded by transplacental transfer of maternal antibodies: vaccination-induced maternal antibodies disappear faster than disease-induced antibodies. In order to maintain protection against measles in infants, it is important to monitor the dynamics of this phenomenon in vaccinated populations. To assess the current situation in France, a multicenter, prospective seroepidemiological study was conducted in seven French hospitals between October 2005 and January 2007. Maternal measles antibody concentrations from 348 infants 0 to 15 months old were measured using the plaque reduction neutralization assay. Geometric mean concentrations and the percentage of infants with maternal measles antibody concentrations above the protection threshold (>or=120 mIU/ml) were assessed according to age. Results show that after more than 20 years of routine measles vaccination in France, maternal measles-neutralizing antibodies decrease dramatically in French infants by 6 months of age, from 1,740 mIU/ml for infants 0 to 1 month old to 223 mIU/ml for infants 5 to 6 months old, and that 90% of infants are not protected against measles after 6 months of age. Infant protection against measles could be optimized both by increasing herd immunity through an increased vaccine coverage and by lowering the age of routine vaccination from 12 to 9 months.

Towards elimination: measles susceptibility in Australia and 17 European countries

OBJECTIVE

To evaluate age-specific measles susceptibility in Australia and 17 European countries.

METHODS

As part of the European Sero-Epidemiology Network 2 (ESEN2), 18 countries collected large national serum banks between 1996 and 2004. These banks were tested for measles IgG and the results converted to a common unitage to enable valid intercountry comparisons. Historical vaccination and disease incidence data were also collected. Age-stratified population susceptibility levels were compared to WHO European Region targets for measles elimination of < 15% in those aged 2-4 years, < 10% in 5-9-year-olds and < 5% in older age groups.

FINDINGS

Seven countries (Czech Republic, Hungary, Luxembourg, Spain, Slovakia, Slovenia and Sweden) met or came very close to the elimination targets. Four countries (Australia, Israel, Lithuania and Malta) had susceptibility levels above WHO targets in some older age groups indicating possible gaps in protection. Seven countries (Belgium, Bulgaria, Cyprus, England and Wales, Ireland, Latvia and Romania) were deemed to be at risk of epidemics as a result of high susceptibility in children and also, in some cases, adults.

CONCLUSION

Although all countries now implement a two-dose measles vaccination schedule, if the WHO European Region target of measles elimination by 2010 is to be achieved higher routine coverage as well as vaccination campaigns in some older age cohorts are needed in some countries. Without these improvements, continued measles transmission and outbreaks are expected in Europe.

Distribution of serum measles-neutralizing antibodies according to age in women of childbearing age in France in 2005-2006: impact of routine immunization

Measles antibody titers were measured in 210 French women. Ninety-four percent had protective values (>120 mIU/mL). Geometric mean titers were significantly different (P < 0.001) between women born before and after 1983, when measles vaccination was recommended (731 and 1358 mIU/mL, respectively). geometric mean titers in 4 age cohorts decreased significantly (P < 0.001) with increasing birth year. These data may help identify the appropriate age for infant vaccination.

Health burden and economic impact of measles-related hospitalizations in Italy in 2002-2003

Background

A large measles outbreak occurred in Italy in 2002–2003. This study evaluates the health burden and economic impact of measles-related hospitalizations in Italy during the specified period.

Methods

Hospital discharge abstract data for measles hospitalizations in Italy during 2002–2003 were analysed to obtain information regarding number and rates of measles hospitalizations by geographical area and age group, length of hospital stay, and complications. Hospitalization costs were estimated on the basis of Diagnosis-Related Groups.

Results

A total of 5,154 hospitalizations were identified, 3,478 (67%) of which occurred in children <15 years of age. Most hospitalizations occurred in southern Italy (71 %) and children below 1 year of age presented the greatest hospitalization rates (46.2/100,000 and 19.0/100,000, respectively in 2002 and 2003). Pneumonia was diagnosed in 594 cases (11.5%) and encephalitis in 138 cases (2.7%). Total hospital charges were approximately € 8.8 million.

Conclusion

The nationwide health burden associated with measles during the 2002–2003 outbreak was substantial and a high cost was incurred by the Italian National Health Service for the thousands of measles-related hospitalizations which occurred. By assuming that hospital costs represent 40–50% of the direct costs of measles cases, direct costs of measles for the two years combined were estimated to be between €17.6 – 22.0 million, which equates to the vaccination of 1.5–1.9 million children (3–4 birth cohorts) with one dose of MMR. The high cost of measles and the severity of its complications fully justify the commitment required to reach measles elimination.

Has the 2005 measles mortality reduction goal been achieved? A natural history modelling study

BACKGROUND

In 2002, the UN General Assembly Special Session on Children adopted a goal to reduce deaths owing to measles by half by the end of 2005, compared with 1999 estimates. We describe efforts and progress made towards this goal.

METHODS

We assessed trends in immunisation against measles on the basis of national implementation of the WHO/UNICEF comprehensive strategy for measles mortality reduction, and the provision of a second opportunity for measles immunisation. We used a natural history model to evaluate trends in mortality due to measles.

RESULTS

Between 1999 and 2005, according to our model mortality owing to measles was reduced by 60%, from an estimated 873,000 deaths (uncertainty bounds 634,000-1,140,000) in 1999 to 345,000 deaths (247,000-458,000) in 2005. The largest percentage reduction in estimated measles mortality during this period was in the western Pacific region (81%), followed by Africa (75%) and the eastern Mediterranean region (62%). Africa achieved the largest total reduction, contributing 72% of the global reduction in measles mortality. Nearly 7.5 million deaths from measles were prevented through immunisation between 1999 and 2005, with supplemental immunisation activities and improved routine immunisation accounting for 2.3 million of these prevented deaths.

INTERPRETATION

The achievement of the 2005 global measles mortality reduction goal is evidence of what can be accomplished for child survival in countries with high childhood mortality when safe, cost-effective, and affordable interventions are backed by country-level political commitment and an effective international partnership.

Increased risk of chronic suppurative lung disease after measles or pertussis in non-vaccinated children

We retrospectively analysed 23 children originating from Campania--Southern Italy--with recurrent pneumonia and chest high-resolution computed tomography (HRCT) proven bronchiectasis. In six patients (26%) who had not undergone measles or pertussis vaccination, recurrent pneumonia started after an episode of lower respiratory tract infection complicating pertussis (n=2) or measles (n=4), contracted at a mean age of 3.6 years. Thirty-three percent (2/6) and 67% (4/6) of the patients had bilateral or monolobar disease, respectively, while in two subjects (33%) bronchiectasis were found in all lobes. These findings indicate an increased risk of developing bronchiectasis after measles or pertussis.