Israel Medical Association Journal

Background: The large number of cases of West Nile fever diagnosed in Israel in 2000 once again brought into focus the confusion that frequently accompanies the use of the term “epidemic”.

Objective: To examine the different definitions of the term “epidemic” and to propose ways in which it can be used to both improve communication among professionals and provide the public with a better sense of the associated risks.

Methods: The literature wes reviewed for the various definitions of the terms “epidemic” and “outbreak”. Sources included popular and medical dictionaries, ancient documents, epidemiology texts, legal texts, and the medical literature.

Result: The term epidemic is variously defined. The broad definition given by epidemiologists - namely, more disease the is anticipated by previous experience - is less meaningful to the general public. In some ways it conflicts with the definitions found in the popular literature, which generally imply danger to the public and a very large number of victims.

Conclusions: The interpretation of the term epidemic may vary according to the context in which it is used. For risk communication, we suggest that every effort be made to add descriptive terms that characterize the epidemic.

Background: Between 1970 and 1979, there was an increase in the incidence of viral hepatitis in Israel with a shift of peak incidence to an older age in the Jewish population, followed by a declining trend during the early 1980s. In July 1999 universal immunization of infants against hepatitis A was introduced.

Objective: To evaluate the chan-ges in the epidemiology of viral hepatitis A in Israel during the past decade.

Methods: Viral hepatitis is a notifiable disease in Israel and cases are reported to the regional health offices, which in turn provide summary reports to the Ministry of Health's Department of Epidemiology. The data in this study were derived from the summary reports and from results of seroprevalence studies.

Results: Following the increase in the incidence of reported viral hepatitis (mainly due to type A) between 1970 and 1979, the rates then stabilized and around 1984 began to decline until 1992. Since then there has been a slight increase. Whereas until 1987 the rates were consistently higher in the Jewish population. since then they are higher in the Arab population. The shift in the peak age-specific incidence from the 1-4 to the 5-9 year age group observed in the Jewish population around 1970 occurred 20 years later in the Arab population. The previously described seasonality is no longer evident. Recent seroprevalence studies indicate that by age 18 years only about 30-40% of the Jewish population have anti-hepatitis A antibodies.

Conclusions: The decline in the incidence of hepatitis probably reflects the changing socioeconomic condition occurring at different times in the two major population groups. Since hepatitis A accounts for almost all the acute viral hepatitis in Israel, the universal vaccination of infants introduced in 1999 should substantially lower the morbidity within the next few years.

Background: Although influenza is usually a mild self-limiting disease it can cause serious complications in high risk groups. The economic costs of influenza are large due to the burden on the health system and absenteeism from work. There is evidence that the vaccine is underused in groups targeted for vaccination.

Objectives: To estimate: a) the compliance rate with the influenza vaccination in Israel during the winter seasons of 1998/1999 and 1999/2000, b) the role of health care personnel and the media in influencing compliance, and c) the reasons for lack of compliance in the elderly.      

Methods: Two national population-based random telephone surveys of 1,500 households were performed during October 1999 and January 2000 to survey influenza vaccination compliance prior to the winters of 1998/1999 and 1999/2000 respectively. Each survey was performed during four successive evenings. The response rate was 78.1% for the first survey and 79.1% for the second.

Results: Vaccination compliance was similar in both surveys. The average rate of vaccination was 6% for the population under 65 years and 50% for the population of 65 years and above. The overall vaccination rate was around 10%. The family physician was the main authority to recommend the vaccination, followed by the community nurse. Absence of recommendation and lack of faith in the efficacy of the vaccine were the main reasons for non-compliance.

Conclusion: Compliance rates with influenza vaccine in targeted groups in Israel remain relatively low. Health care personnel should be more involved in promoting the vaccine.
 

Background: In trials comparing different formulations of measles vaccine, excess non-specific mortality occurred in female children who received high titer vaccine. These findings suggest a gender-specific effect of measles vaccine.

Objectives: To determine whether gender differences exist in the rates of adverse reactions and morbidity in the month following immunization with measles-containing vaccine, and to evaluate whether there is a gender-specific association between the humoral immune response to measles vaccination and post-vaccination morbidity.

Methods: Parents completed questionnaires on the health status of 755 infants aged 15-20 months, during the month preceding and the month following the measles-mumps-rubella vaccination. Blood samples were tested for measles antibody titers in a subsample of 237 infants.

Results: After controlling background morbidity in the infants, the relative risk of fever and rash following vaccination was 2.35 in females and 1.36 in males. The geometric mean antibody titers against measles were similar in both sexes and there was no significant association between antibody titer and post-vaccination morbidity in either sex.

Conclusions: Our findings demonstrate higher rates of adverse effects in females following vaccination with MMR vaccine, irrespective of the humoral response. This study emphasizes the need to consider possible gender differences when evaluating new vaccines.

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MMR= measles-mumps-rubella