Measles epidemiology in Italy

Age patterns and transmission characteristics of hand, foot and mouth disease in China

Background

Hand, foot and mouth disease (HFMD) has circulated in China and caused yearly outbreak. To understand the transmission of the disease and to assess the spatial variation in cases reported, we examined age-specific transmission characteristics and reporting rates of HFMD for 31 provinces in mainland China.

Methods

We first analyzed incidence spatial patterns and age-specific incidence patterns using dataset from 2008 to 2012. Transmission characteristics were estimated based on catalytic model. Reporting rates were estimated using a simple mass action model from “Time Series Susceptible Infectious Recovered” (TSIR) modeling.

Results

We found age-specific spatial incidence patterns: age-specific proportions of HFMD cases varied geographically in China; larger case percentage was among children of 3–5 years old in the northern part of China and was among children of 0–2 years old in the southern part of China. Our analysis results revealed that: 1) reporting rates and transmission characteristics including the average age at infection, the force of infection and the basic reproduction number varied geographically in China; 2) patterns of the age-specific force of infection for 30 provinces were similar to that of childhood infections in developed countries; the age group that had the highest infection risk was 3–5 years old in 30 provinces, and 10–14 years old in Tibet; 3) a large difference in HFMD transmission existed between northwest region and southeast region; 4) transmission characteristics determined incidence patterns: the higher the disease transmission in a province, the earlier the annual seasonality started and the more case percentage was among children 0–2 years old and less among 3–5 years old.

Conclusion

Because HFMD has higher transmission than most childhood infections reported, high effective vaccine coverage is needed to substantially reduce HFMD incidence. Control measures before the vaccine implementation should focus on 2–6 years old children in 30 provinces and 10–14 years old children in Tibet.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-2008-y) contains supplementary material, which is available to authorized users.

Systematic Review of Measles and Rubella Serology Studies

Serological tests provide information about individual immunity from historical infection or immunization. Cross-sectional serological studies provide data about the age- and sex-specific immunity levels for individuals in the studied population, and these data can provide a point of comparison for the results of transmission models. In the context of developing an integrated model for measles and rubella transmission, we reviewed the existing measles and rubella literature to identify the results of national serological studies that provided cross-sectional estimates of population immunity at the time of data collection. We systematically searched PubMed, the Science Citation Index, and references we identified from relevant articles published in English. We extracted serological data for comparison to transmission model outputs. For rubella, serological studies of women of child-bearing age provide information about the potential risks of infants born with congenital rubella syndrome. Serological studies also document the loss of maternal antibodies, which occurs at different rates for the different viruses and according to the nature of the induced immunity (i.e., infection or vaccine). The serological evidence remains limited for some areas, with studies from developed countries representing a disproportionate part of the evidence. The collection and review of serological evidence can help program managers identify immunity gaps in the population, which may help them better understand the characteristics of individuals within their populations who may participate in transmission and manage risks.

A Bridge Too Far - Revisited: Reframing Bruer's Neuroeducation Argument for Modern Science of Learning Practitioners

In Education and the Brain: A Bridge Too Far, John Bruer argues that, although current neuroscientific findings must filter through cognitive psychology in order to be applicable to the classroom, with increased knowledge the neuroscience/education bridge can someday be built. Here, we suggest that translation cannot be understood as a single process: rather, we demonstrate that at least four different ‘bridges’ can conceivably be built between these two fields. Following this, we demonstrate that, far from being a matter of information lack, a prescriptive neuroscience/education bridge (the one most relevant to Bruer’s argument) is a practical and philosophical impossibility due to incommensurability between non-adjacent compositional levels-of-organization: a limitation inherent in all sciences. After defining this concept in the context of biology, we apply this concept to the learning sciences and demonstrate why all brain research must be behaviorally translated before prescriptive educational applicability can be elucidated. We conclude by exploring examples of how explicating different forms of translation and adopting a levels-of-organization framework can be used to contextualize and beneficially guide research and practice across all learning sciences.

Deciphering the relative weights of demographic transition and vaccination in the decrease of measles incidence in Italy

In Italy, during the course of the past century to the present-day, measles incidence underwent a remarkable decreasing trend that started well before the introduction of the national immunization programme. In this work, we aim at examining to what extent both the demographic transition, characterized by declining mortality and fertility rates over time, and the vaccination programme are responsible for the observed epidemiological pattern. Making use of a non-stationary, age-structured disease transmission model, we show that in the pre-vaccination era, from 1901 to 1982, the decline in birth rates has resulted in a drastic decrease in the effective transmission rate, which in turn has determined a declining trend of measles incidence (from 25.2 to 10.3 infections per 1000 individuals). However, since 1983, vaccination appears to have become the major contributing factor in the decrease of measles incidence, which otherwise would have remained stable as a consequence of the nearly constant birth rates. This led to a remarkable decrease in the effective transmission rate, to a level well below the critical threshold for disease persistence. These findings call for the adoption of epidemiological models, which deviate the age structure from stationary equilibrium solutions, to better understand the biology of infectious diseases and evaluate immunization programmes.

The incidence and notification of measles in Australia

The incidence of measles in Australia in 1986 was estimated as 43 per 100,000 population, high by the standards of countries where immunization levels are high, low by the standards of countries where immunization levels are low. It is estimated that only 5 per cent of cases are notified in New South Wales, one of only 2 States which require notification. The reasons for this, its significance and a possible remedy are discussed.

The pre-vaccination regional epidemiological landscape of measles in Italy: contact patterns, effort needed for eradication, and comparison with other regions of Europe

Background

Strong regional heterogeneity and generally sub-optimal rates of measles vaccination in Italy have, to date, hampered attainment of WHO targets for measles elimination, and have generated the need for the new Italian National Measles Elimination Plan. Crucial to success of the plan is the identification of intervention priorities based upon a clear picture of the regional epidemiology of measles derived from the use of data to estimate basic parameters. Previous estimates of measles force of infection for Italy have appeared anomalously low. It has been argued elsewhere that this results from Italian selective under-reporting by age of cases and that the true measles force of infection in Italy is probably similar to that of other European countries. A deeper examination of the evidence for this conjecture is undertaken in the present paper.

Methods

Using monthly regional case notifications data from 1949 to the start of vaccination in 1976 and notifications by age from 1971–76, summary equilibrium parameters (force of infection (FOI), basic reproductive ratio (R₀) and critical vaccination coverage (p_c)) are calculated for each region and for each of 5 plausible contact patterns. An analysis of the spectra of incidence profiles is also carried out. Finally a transmission dynamics model is employed to explore the correspondence between projections using different estimates of force of infection and data on seroprevalence in Italy.

Results

FOI estimates are lower than comparable European FOIs and there is substantial regional heterogeneity in basic reproductive ratios; certain patterns of contact matrices are demonstrated to be unfeasible. Most regions show evidence of 3-year epidemic cycles or longer, and compared with England & Wales there appears to be little synchronisation between regions. Modelling results suggest that the lower FOI estimated from corrected aggregate national data matches serological data more closely than that estimated from typical European data.

Conclusion

Results suggest forces of infection in Italy, though everywhere remaining below the typical European level, are historically higher in the South where currently vaccination coverage is lowest. There appears to be little evidence to support the suggestion that a higher true force of infection is masked by age bias in reporting.

Heterogeneity in regional notification patterns and its impact on aggregate national case notification data: the example of measles in Italy

BACKGROUND

A monthly time series of measles case notifications exists for Italy from 1949 onwards, although its usefulness is seriously undermined by extensive under-reporting which varies strikingly between regions, giving rise to the possibility of significant distortions in epidemic patterns seen in aggregated national data.

RESULTS

A corrected national time series is calculated using an algorithm based upon the approximate equality between births and measles cases; under-reporting estimates are presented for each Italian region, and poor levels of reporting in Southern Italy are confirmed.

CONCLUSION

Although an order of magnitude larger, despite great heterogeneity between regions in under-reporting and in epidemic patterns, the shape of the corrected national time series remains close to that of the aggregated uncorrected data. This suggests such aggregate data may be quite robust to great heterogeneity in reporting and epidemic patterns at the regional level. The corrected data set maintains an epidemic pattern distinct from that of England and Wales.

[Measures of the effect of vaccination in an outbreak of measles]

Vaccine efficacy, the effectiveness of a vaccination programme and the fraction of a population that would be necessary to vaccinate in order to prevent a measles outbreak are studied in a population having a vaccination programme. A dynamic model for acute, directly transmitted diseases was applied, based on the rate of transmission, namely, the probability that the infectious agent is transmitted from an infected to a susceptible person within a short space of time. We carried out a population-based study where we observed the final attack rates among vaccinated and unvaccinated people for a measles outbreak. In this population, the vaccination programme is responsible for a reduction of: 82.41% of all cases in the non-vaccinated sector; 98.45% of the average risk of disease among the vaccinated; and 97.29% of all cases among the population as a whole. Under these conditions there is the possibility of disease outbreaks arising, outbreaks which could be prevented if the percentage of the vaccinated population exceeded 95%.

Seroepidemiology of measles in Catalonia (Spain) 1985-1986

A seroepidemiological study of measles immunological status was carried out among four different populations: schoolchildren of 6-7 years, 10-11 years and 13-14 years, and pregnant women of 18-45 years, in Catalonia, Spain; 1,213 children and 239 pregnant women were surveyed. The measurement of measles antibodies were made by indirect immunofluorescence, with antibody titres greater than or equal to 1:8 considered as positive. The prevalence of measles antibodies was 82.9% in the 6-7 year old group, 87.2% in the 10-11 year old group and 94.4% in the age group 13-14 years. Among pregnant women, the prevalence of antibodies was 96.2%. Two of the variables studied were associated with the prevalence of measles antibodies in schoolchildren: the disease antecedents and measles vaccination. In pregnant women aged 18-45 no variable had any statistically significant association with the prevalence of measles antibodies.

Year of birth, sex and residence, as "determinants" of tetanus incidence and immunity in Italy

Regional results of a seroepidemiological study and official notification data are evaluated to describe the situation of tetanus in Italy. Tetanus incidence has been decreasing during the past years. Vaccination has been the principal means of tetanus prevention. Trend analyses for sex- and age-specific rates suggest a change of exposure, presumably linked to the transformation of the Italian society after the World War II, a higher incidence among the elderly as a function of poor coverage and vanishing immunity. Regional data show remarkable variability in prevalence of susceptible population. Reported rates by region are different. Different degrees of regional underreporting in case notification is suggested.

Immunity to tetanus among Italians born between 1956 and 1963

Systematic mandatory immunization of children against tetanus begun in Italy in 1968. Preceding birth cohorts, accounting for almost 80% of present Italian population, were poorly immune or totally non-immune; around 90% of cases of tetanus occurring in Italy in recent years are observed among them. In a national sample of 4770 young males born between 1956 and 1963, about one third was not protected. Prevalence of non-immune subjects was greater in the Southern Regions and the Islands, in rural areas, among the unemployed, among the older birth cohorts.