[ effect of age group under 15 years on cholera morbidity during the past 10 years in Iran [1996-2005]]

The study of the effect of age, especially children under 15 years, on cholera morbidity during a period often years [1996-2005] was carried out in Iran. There are no other studies on this topic in Iran and other countries. In this cross sectional study, we used cholera surveillance data collected in Center for Disease Control. All cholera cases were divided into two groups: under 15 years and above 15 years. Incidence rate of cholera per 100000 was calculated in total population and the two mentioned groups during 10 years. The relative risk of less than 15 year-olds group to above 15 year-olds was calculated with95% CI for 10 years by EPI6 and SPSS software. The trend of cholera incidence during the past 10 years shows two epidemic peaks in 1998 and 2005 by the rate of 15.7 and 1.63 per 100000, respectively. During the year with no epidemic and the years between two peaks, the age group under 15 year-olds was more affected with significant relative risk. For example, in 2001 this rate was 4.53. So, we can consider this age group as a risk factor to cholera morbidity. The age group of above 15 year-olds was more affected to cholera during epidemic years [1998, 2005] and relative risk was less than one. So, the age was protective on cholera morbidity for children in these years. One of the most important causes of periodic cholera epidemics every 5-6 years is changing of herd immunity. During the years between two epidemics adults have sufficient immunity and children are more affected because of first exposure and less immunity. With reduced herd immunity epidemics occur. We recommend continuing and strengthening of cholera surveillance system for detection of epidemics and treatment of highly sensitive age groups

[Relationship between occurrence of guillan-barre syndrome and mass campaign of measles and rubella immunization in Iranian 5-14 years old children]

Several case reports and epidemiologic studies have reported a relation between different vaccines including measles, rubella, and mumps and Guillain-Barre syndrome [GBS]. In this study we investigated relation between receiving measles and/or rubella vaccines and occurrence of Guillain-Barre syndrome after national immunization campaign in 2003 in Iran. In this study we used National Surveillance system for acute flaccid paralysis data from the beginning of 2002 to the end of 2004. We studied 5-14 year-old children. Three-year time span of the study was divided into fifteen 10 weeks periods, and number of reported and approved cases of Guillain-Barre syndrome in each time period has been analyzed supposing their distribution was according to Poisson distribution. One of time periods has been chosen in a manner that its first 4 weeks included embedded National Immunization and following 6 weeks were designated for covering incubation period of Guillin-Barre syndrome. Of total 553 reported flaccid paralysis cases in 5-15 year-old children 370 were approved to be Guillain-Barre [67%]. Estimated average incidence of Guillain-Barre syndrome in<15 year-olds is 1/100,000/year [95% CI: 0.88-13], and in 5-15 year-old children is 0.6/100,000/year [95% CI: 0.58-083]. Thus, number of expected cases in 25 cases each 10 weeks time period was 23.8 of GBS that were reported in the time period which coincided with immunization campaign. Probability of occurring>/=25 cases of GBS in that time period according to Poison distribution with expected case numbers of 23.8 is equal to 0.43 [P=0.43]. Yearly incidence rate of GBS in this study was similar to other studies. According to our results, there was no increase in GBS incidence in the 4 weeks national Immunization Campaign and 6 weeks after it in comparison to other 10 weeks periods before or after this time period