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Epidemiology of vaccine preventable diseases
Epidemiology of vaccine preventable diseases
measles سورێژە , rubella کۆکە , mumps, polio ئیفلیجی منداڵان
Measles
Definition:
> measles or rubeola is an acute viral (paramixovirus RNA type) infection with maculopapular rash erupting successively over the neck and face , trunks, arms, and legs and accompanied by a high fever.
> Is a highly contagious infection تووشبوونێکی زۆر درمییە with 90% of household contacts acquire infection.(secondary attack rate)
> Human is the only host.
> The virus is unstable in environmental situation, is sensitive to dry situation ,light and proteolytic enzymes but could remain in micro droplets in averaged humidity for several hours.
Clinical stages of measles
1- incubation period: 10-12 days,
dominant finding: leukopenia
2-Preliminary stage : قۆناغی سەرەتایی
2-3 days,
symptoms: fever, anorexia, restlessness,
continued: cough, runny nose, conjunctivitis هەوکردنی پێڵوی چاو, photophobia, late appearance Koplik spot 1-3 mm blue-white in the oral mucosa
3- The final stage: the appearance دەرکەوتنی of maculopapular rash on the face and forehead, spreading to the abdomen and extremities.
Disease complications: otitis media هەوکردنی گوێی ناوەڕاست, pneumonia هەوکردنی سییەکان
Laboratory diagnosis: serology, the presence of IgM or a 4-fold increase in antibody during the recovery period compared to the acute stage.
koplik spot appear in which stage?
preliminary stage
General epidemiology
> The transmission method is either direct through micro droplets or indirectly through droplet nuclei through the air.
The contagious period is from 4 days before to 4 days after the appearance of skin rash.
The reservoir of the disease is human and the healthy carrier state has not been reported in this disease.
All non-vaccinated people are at risk.
A single infection or vaccination against the disease gives lifelong immunity.
Epidemiology of disease in Iran
> The implementation of the general immunization program with the aim of covering more than 95% in the age group of 5-25 years
جێبەجێکردنی بەرنامەی کوتانی گشتی بە ئامانجی داپۆشینی زیاتر لە 95% لە گروپی تەمەنی 5-25 ساڵ
the implementation of the national surveillance program based on suspected cases.
جێبەجێکردنی بەرنامەی چاودێری نیشتمانی لەسەر بنەمای حاڵەتە گومانلێکراوەکان.
Measles virus has one serotype, but so far eight groups (A-H) and 23 different genotypes have been identified and reported.
The native genotype of Iran is type D4.
Prevention and control of measles in Iran
> Preventive measures: two injections of live attenuatedلاوازکراوی زیندوو vaccine, which is injected in the national program along with rubella and mumps vaccine (MMR) at the ages of 12 and 18 months.
More than 95% of children will be protected by the first dose at 12 months of age.
Measles surveillanceچاودێری کردن system: with the aim of eliminating نەهێشتنی the disease in the country, it is one of the diseases reported by telephone (urgent).
> elimination definition: If there is no case of measles in one year.
> How to implement the surveillance system: daily reporting of all suspected cases (clinical symptoms of fever, maculopapular rash) to higher levels and investigation of cases within less than 48 hours in the form of sampling of the nasopharynx and urine and sending to the measles reference laboratory (Faculty of Health, University of Medical Sciences Tehran)
چۆنیەتی جێبەجێکردنی سیستەمی چاودێری: ڕۆژانە ڕاپۆرتکردنی هەموو حاڵەتە گومانلێکراوەکان (نیشانە کلینیکیەکانی تا، پەڵەی ماکولۆپاپولەر) بۆ ئاستێکی بەرزتر و لێکۆڵینەوە لە حاڵەتەکان لە ماوەی کەمتر لە ٤٨ کاتژمێردا لە شێوەی وەرگرتنی نمونەی لووت و میز و ناردنی بۆ ئاماژەی سورێژە تاقیگەی (فاکەڵتی تەندروستی، زانکۆی زانستە پزیشکییەکانی تاران)
> Sending zero weekly report if there are no suspicious cases
> Controlling contacts and the surrounding environment: isolating patients and preventing them from going to work or school for 4 days after the appearance of the rash, and for patients with immune disorders until the end of the disease period.
Investigating لێکۆڵینەوە the contacts of patients and identifying the source of infection with the aim of preventing the spread of the disease and vaccinating the contacts.
> Treatment: No specific treatment is recommended. Immunoglobulin administration is recommended for people at high risk, such as pregnancy or immunodeficiency, or vitamin A administration for malnourished people.
Actions in epidemics: Vaccination of all children who have not received two doses of vaccine in kindergartens and schools. Use of immunoglobulin in susceptible people in epidemic areas.
Rubella
> rubella (German measles):usually is a mild illness but with a documented teratogenic effect due to maternal infection during pregnancy and infection of placenta and fetus resulting structural damages and abnormalities.
ڕوبێلا (سورێژەی ئەڵمانی): بەزۆری نەخۆشییەکی سووکە بەڵام کاریگەرییەکی بەڵگەنامەیی تێراتۆجینیکی هەیە بەهۆی هەوکردنی دایکی لە کاتی دووگیانی و هەوکردنی منداڵدان و کۆرپەلە کە لە ئەنجامدا زیانەکانی پێکهاتەیی و نائاسایی دەبێت.
Also is called a 3 days measles
Is a RNA virus from togaviride family with only one serotype and 13 different genotypes.
Most clinical findings are low fever, malaise, morbilliform rash and more serious complications are thrombocytopenia and encephalitis.
Congenital rubella is a serious condition, which involves more than 85% of the fetuses during first semester of pregnancy.
Most important clinical findings are deafnessکەڕبوون , heart anomalies, cataract ئاوی سپی چاو , microcephaly, mental retardness دواکەوتوویی دەروونی , bone problems and liver , spleen damages.
Epidemiological factors
> a seasonal pattern with maximum incidence in late winter and early spring
. The importance of the disease is due to the occurrence of abortion and congenital malformation syndrome (CRS).
The average incubation period is 10 days (up to 23 days). It is possible to transmit through aerosols from one week before to two weeks after the appearance of skin rashes.
Lifetime immunity will be acquired if infected.
classical triad of rubella
classical triad
> cataract
> cardiac abnormalities
> deafness
other manifestations :
growth retardation rash
hepatosplenomegaly
jaundice
meingoencephalitis هەوکردنی پەردەی مێشک
CNS defects lead to moderate to profound mental retardition
Epidemiology of disease in Iran
> rubella is an endemic disease of the country.
It has one serotype and 13 different genotypes. The genotype of Iranian rubella is type B2.
Several seroepidemiological studies have reported 78-94% immunity to rubella in reproductive age before universal vaccination in the country.
In urban areas and in lower socio-economic levels, the level of safety is higher. (Effect of population density on immunity)
rubella prevention and control measures in the country
> Immunization is the most important measure to prevent rubella and congenital rubella syndrome.
Immunization of girls of puberty age, women of reproductive age and seroepidemiological studies to ensure the safety of women of reproductive age are important strategies to prevent congenital rubella.
Rubella vaccine is injected in the form of MMR combination at the ages of 12 and 18 months.
In order to eliminate congenital rubella, it is recommended to immunize girls of puberty and reproductive age.
It is forbidden to administer the vaccine to pregnant women and it is recommended to avoid pregnancy for one month after receiving the vaccine.
It is among the diseases subject to telephone reporting (urgent).
Control of patients and contacts
> Affected children should be banned from school for a week after the onset of the rash.
Susceptible people should avoid contact with people suspected of having rubella. Infants with congenital rubella may shed the virus for a year or more after birth. (The need for proper isolation and examination in terms of excretion of the virus in the urine and throat after 3 months)
Necessary measures during outbreaks: universal vaccination plus vaccination of children older than 6 months
3\ Mumps
> Mumps (infectious parotitis): is a viral(RNA paramixovirus) infection of salivary parotid gland (chipmunk cheeks) usually in 5-9 year children.
It can lead to meningitis (<15%), brain inflammation (<1%), deafness , painful testicular swelling (25% of adult males) and sterility.
In 1/3 cases is asymptomatic. Usually has some prodromal sings like myalgia, malaise, low fever and headache. Parotitis (unilateral or bilateral) occurs in 30%-40% of cases.
Diagnosis is based on clinical symptoms and lab exams including viral culture, serology and PCR.
Saliva (first 4-5 days), urine (up to 2 weeks) and CSF (first 8-9 days) in case of meningitis are proper samples for diagnosis.
Epidemiology
> The only natural host of the virus is humans.
It has only one serotype and 12 different genotypes (A-L).
It is less contagious than measles and chicken pox.
The most asymptomatic cases are at the age of 2-3 years, and the clinical cases increase with age. (90% of cases are symptomatic in 10-14 years)
Transmission is possible through saliva and respiratory droplets and contaminated equipment.
The average incubation period is 18 days (14-24 days) and the ability to spread is from 6 days before to 9 days after swelling of the salivary glands. (The maximum infection is from 2 days before to 4 days after the salivary glands involvement)
There is lifelong immunity in case of infection.
