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Communicable Disease Control for Measles

 Surveillance define as the maintenance of ongoing watch on the health status of group or community, it is a data collection for action (WHO). Or

Surveillance has being defined as by the World Health Organization as the ‘continuing scrutiny in all aspects of the occurrence and spread of disease that are pertinent to effective control’.

Many communicable disease control are observed by local government and studies under state government, then this collection state data is forwarded National level for control activities in outbreaks, which affects more than one authority, to monitor the need and impact of national programs & to guide in the development of research projects, evaluate hypothesis and portray changes in properties of infectious agent. It also helps in quarantine activities and to expedite international cooperation to report World Health Organisation.

The surveillance system is studied under the national notifiable diseases surveillance system (NNDS) was established in 1991, under the successful network of the Communicable Diseases Network Australia New Zealand (CDNANZ).The CDNANZ monitors the incidence of an agreed list of communicable diseases in Australia.(Australia’s notifiable diseases status)and guidelines for control of outbreaks in Australia which was developed by National Health And Medical Research Council (NHMRC) deals with individual cases and out break control which revise Measles Control Campaign (MCC).

A surveillance system consists of information of occurrence of infectious & chronic disease, environment including occupational exposure, behavioural characteristics, nutritional status and medical services. Hence surveillance classify as:-

•·       Disease surveillance.

•·       Nutritional surveillance.

•·       Serological surveillance.

•·       Epidemiological surveillance.

•·       Demographic surveillance.

•·       Environmental surveillance.

 

Methods

    Data collected by different methods of surveillance:-

•1.)  Routine reporting system (Both active & passive surveillance):- number of illness records collects from medical practitioner.

•2.) Sentinel reporting system: – illness, deaths, age, immunisation status obtained from paediatric hospital, general practitioners, pathologist, diagnostic and public health laboratory.

•3.) Community based sentinel surveillance: - illness, modifying local analysis & feedback, advocating community promotion for – intervention; treatment; follow up.

•4.) Case /outbreak investigations: – determine and study number of illnesses, number of deaths, age, sex, immunisation status, name & address, extent of outbreak and clinical symptoms.

•5.) Special studies: – number illness, number deaths, socio-economic status and population at risk.

The different methods are complementary to each other.

The levels of surveillance differ:-individual surveillance of infected persons, local population/community surveillance, national and international surveillance for e.g. influenza.

 

Surveillance system for measles has been formulated to eradicate measles from nation; first epidemic outbreak of measles was noticed in 1993 and 1994. There were 498 cases recorded to NNDSS in 1996 with per year rate 2.7 per 100,000 populations. Peak incidence of occurrence in month of August to October and more than 70% of cases were 20 years or below, more incidence in male than female ratio is 1.1:1.

Recent data obtained from NSW residents, shows peak incidence in month of January to July in 2006-2007, cases were obtained more than 30 per population. The measles rate of notification got declined since outbreak in 1994.but, cases still find in adolescence group who hadn’t being vaccinated or accidentally exposed .

The World Health Organisation, the Centers of Disease Control Prevention organised worldwide Measles elimination project.

The objective was to decrease morbidity and mortality cases in society or community and to prevent from remission of measles until global target is not achieved, by maintaining low level of susceptibility and to eliminate measles. Measles elimination is defined as interruption of transmission in a sizeable geographic area but, because of continued threat of reintroduction of virus, vaccination need to be continued.

Surveillance system for measles

II. Measles surveillance target should have following:-

•1.) Proper case definitions.

•2.) Diagnosis and proper serological, laboratory investigation.

•3.) Enhancing surveillance.

•4.) Outbreak investigation.

•5.) Monitoring measles vaccination coverage and population susceptibility.

•6.) Monitoring vaccine safety and effectiveness.

 

Despite routine reporting and surveillance system provides incomplete picture. It must cover all measles cases which come for treatment to health facilities; measles is more commonly dealt at home or there should be investigated.

All health facilities should be checked regularly for proper reporting and all cases which are unnoticed and not diagnosed by health care /by health staff should be reported regularly. A paediatric phlebotomist should appoint for the collection of samples in the patient’s home regularly, it was found successful in July 1997, where positive result obtained from 258 of 317.

The number of measles cases has continued to fall markedly after outbreak in 1993 and 1994.

 

III. Case definition

For measles eradication, disease surveillance must fulfil several functions. In addition to measuring case rates and charactersticing population at high risk, have large susceptibility for infection, for that we need to fulfil these;-

•1.    Detect cases and the origin of infection quickly so that control measures can be implemented;

•2.    Detect interruption or resurgence of  indigenous measles transmission;

•3.    Detect importation measles;

•4.    Monitor serious complications measles infection (death, encephalitis, seizures and pneumonia).

•1.                 Case definition for measles should have following:-

•1.    It should be serological or virological evidence of acute measles.

For serological and virological evidence, the serum is collected early (within 72 hours of onset), isolation of wild measles virus should be from clinical specimen; A diagnostic rise in measles antibody titre s in paired. Mostly 23 percent of true measles cases may not develop IgM response in that case is rejected. Although measles IgM positive, we classify cases that have been vaccinated within 45 days of specimen collection as ‘rejected’ (unless epidemiological laboratory confirm cases) as the antibody response consideration due to vaccine virus.

Suspected infection- a person with an illness including all clinical features.

•2.    Two of the following:

•·       Prodromal stage: – which includes injected conjunctivae, fever and cough.

•·       White specks on a red base in the mucous membranes of the cheeks (Koplik’s spots).

•·       Morbilliform rash ,confluent maculopapular eruption spreading over face and body ,or

•3.    An atypical exanthematous eruption in a partially immune person during an epidemic of measles.

•4.    Epidemiological linkage:-

•·        There was exposure to laboratory and case confirmed during it infectious period (4 days onset of rash appearance and after).

•·       This exposure occurred within the expected incubation period of the case under investigation: 7-18 days, before onset of rash.

•5.    International importation: – it is define as confirmation of cases within 18 days of arrival in Australia. Similarly, interstate are confirmed cases whose rash onset is within 18 days of entering the state / territory.

•6.    Laboratory diagnosis:-in laboratory diagnosis cases should take care of specificity and sensitivity of case, specificity is defined as specific reagent should be collected in specific time period or duration.

Sensitivity means sensitive for reaction.

Serological diagnosis- IgM antibody is considered to be best diagnostic criteria for measles. The indirect enzyme immunoassay (EIA) (Behring Enzygnost) is recommended for routine laboratory investigation, because it is rapid and convenient to perform.in this serum of measles specific IgM is not detected for IgM is not detected are tested for IgM and IgG antibodies to parvovirus B19 by EIA (biotin).

The sensitivity and specificity obtained were to be 86 percent to 81 percent respectively.

The assays are found to be positive at the onset of rash illness, about 80 percent sensitive within 72 hours within 72 hours. Hence, repeated serum sampling for IgM and IgG is recommended after 14 days. However, alternative methods has being practising such as, IgG seroconversion (change from negative to positive)  or rise in measles specific IgG antibodies. Generally peaks approximately two weeks after onset of rash, variety of methods are there:-a) IgG or total antibody, Plaque reduction neutralisation (PRN).Quantitive assays such as immunofluorescent assays, neutralisation, and haemagglutination inhibition (HAI) .complement fixation tests (CFT) and PRN.

But, CFT cannot routinely perform hence it is no longer in use for measles diagnosis and HAI is known for inferior sensitivity compared to modern assays. 

Many countries for instance:- France and united kingdom ; use routinely salivary measles IgM antibodies testing it has been estimated  measles specific IgM  antibodies in greater than 90 percent of cases where measles IgM is present in serum.

But ,unfortunately this test is not use, only reason is salivary detection of measles IgG antibodies is very insensitive compared with detection in serum.

Genotyping is very sensitive method which has been use in Victorian Infectious Disease Reference laboratory (VIDRL) in Victoria. In this serum is tested from primary case was negative for measles virus RNA by PCR, the people those are infected identified with ‘D8′ same novel of genotype, but it has been practised by all laboratory it is highly specific to know genotype of virus and test is very sensitive.

IV. Case investigation.

After completing case definition it is important to have accurate collection and complete immunisation history, including all details number of doses and dates when measles vaccine had being given.Proper collection of demographic data which helps characterise cases and detect temporal or geographic distribution of number of cases, it helps in monitoring disease outcome, such as death and encephalitis, main function is to prevent from severe illness and defect.

V. Active surveillance.It is use to find out deficiency areas of low vaccination coverage and low measles incidence, which involves direct investigation in schools, doctors, laboratories and hospital seeking cases that have not been notified.

Reviewing additional disease registers or data sets which are not routinely identified by anyone, for example – emergency department in hospital and laboratory registers.

Alternative data are inpatients statistic and number of mortality data in hospitals.

VI. Sentinel surveillance:-

Two or three units are selected in particular district since they are found to be regularly and reliability reporting and check number of patients with measles , example in district hospitals, infectious disease hospital ,paediatric hospitals, etc. The centres should be chosen is smaller and carefully.

Disadvantage of this process that report data from only few population whose representativeness are unknown, it doesn’t cover entire area of population. The sentinel system is very useful for discerning trends of measles and patterns of common infectious diseases, it’s provide long term evaluation information and programme planning for day to day public considerations. But such systems are rare and low when disease is endemic because of low percentage of sentinel GP as compare to the GP in the country, it is found to be same in all in developed nationals.

VII. Community surveillance

Community surveillance for measles control has got limited number approach and can be integral part of primary health care centre by linking village guides, women’s group, school teachers and all others primary group facilities.

Special studies:-

That conducted by health staff, investigators or epidemiologists. They are needed to measure the number of cases of measles in an area. Community-based, house to house survey, or sample surveys may be necessary. Only drawback is that they are expensive and really require expertise personnel.

Monitoring surveillance quality is get by taking proportion of all cases that are subjected to laboratory testing for measles; median time of collection from onset of measles reaction or eruption of rash, that specimen collection is notified to state health authority: and total percentage of cases with data on current immunisation status.

VIII. Outbreak investigation.

  They are carried out toby :-Confirm diagnosis, to indicate which is the most appropriate method, to rule out where and to whom to apply these preventive measures, it determine why the outbreak has occurred and what are prevention of similar other outbreaks. For this two or more laboratory confirmed cases which are related in time and place, or single laboratory confirmed case in institution.

 

•1.    Monitoring outbreaks

Collecting outbreak data helps to evaluate more detail in surveillance method, and regional frequency of health problem and how health area is enable to control outbreak. The time interval between May also studied under region and can be used to anticipate the timings of outbreaks.

•2. Monitoring vaccination coverage and monitoring        population susceptibility.

A.)Monitor the routine immunisation.

Vaccination proper coverage is key indicator of campaign success and to predict control on measles.

The Australian Childhood immunisation Register (ACIR) is dealing with quarterly reports for measles coverage on children who were born in 1996 since ACIR recommended first. The basic coverage from state level to national level get reports for measles coverage on cohorts of 2 year old children who were born in 1996.but now it is routinely done and routine performance shows the quality coverage. In addition to it mechanism is being helpful to identify target region which are not covered by vaccination programme.

As a result, present data result gave idea for coverage; hence the second dose of measles MMR vaccination brought forward and is given to preschool children.

B.)Mass susceptibility.

As measles is controlled and now rare, the estimative population of susceptibility obtained from serological is important source of information for regarding success of measles elimination program. The regular serological survey should test for range of vaccine preventable disease including measures, the blood samples from immunocompromised patients should be excluded.

This serological surveillance will help to identify the effects of second MMR dose from adolescence to preschool children, allow monitoring success of vaccination MMR and also helps to rule out prevalence of susceptibility of rubella in child bearing mothers.

This data may helpful in mathematical modelling for time duration, size, morbidity, mortality, and age distribution of outbreak. Serological surveillance method has been used routinely in Britain for 10 years and in mass campaign help to study in outbreak of measles in New Zealand.

3.  Monitoring vaccine safety and effectiveness.

Mass campaign for vaccine adverse effects is to monitor MMR vaccine and safety record for future reference.

The adverse effect of measles vaccine shows -fever, occurs in 6 to 11 day after vaccination is commonly denoted as adverse event. This program helps to explain that adverse effect is temporary and this should be done to maintain public confidence, the adverse events of vaccine should be high priority .it is important to inform doctors and measles staff regarding possible adverse events and remind doctors for regular reporting of adverse events patients.

During mass vaccination campaign, state/territory must include various other events of mass vaccination such as.

Serious adverse are following vaccination define as:-

The occurrence of one or more condition in 48 hrs, persistent screaming, temperature more than 40.5 degree Celsius, anaphylaxis and shock and hypotonic/hypo responsive episodes or the occurrence of symptoms in 30 days such as ;- encephalopathy, convulsions, aseptic meningitis ,thrombocytopenia, acute flaccid paralysis, death and other serious event thought to be associated with a vaccinations. The AEs aims should be to identify and report regularly all serious events in childhood and this report should publish regularly.

IX. Success of surveillance:

The success of the concept of surveillance is demonstrated by the total successful eradication of disease for instance smallpox is completely eradicated, similarly malaria and guinea worm has most successful rate. When the measles completely eradicated universally then it will be considered as total success.

Recently in January 2001 a 19 year old Sydney resident who had being returned from India visited Melbourne for 4 days while with infectious measles and further more subsequently more than 50 case has been identified, mainly in young adult, repeated number of case now found in young adult remained highest risk of measles in Victoria being noted the strategies for young adults. Hence, program has been remodified for young adult as well; vaccination dose of measles is for below 10 months and booster dose for subsequent cases in age range 17-29 years should be revised with dose.

 

 Conclusion.

This surveillance system for measles differs from other common disease pertussis and diphtheria because, the measles is  now rare disease in Australia and almost rarely case be obtained so far, but other disease such as pertussis is not categorise in rare disease and not in stage of complete eradication, measles is viral disease it is found to most commonly affected more number of case to male than compare to females incidence rate of measles is 1.4:1 ,whereas pertussis female ratios are high which is male:female-1:1.3 and it is highest in all age group under 15 years old with smaller secondary peaks among adult age 35-44 years but in case of measles most commonly infected case observed are below 5 yrs and secondary peak still below age of 20 years old in adolescences age, the rate of annual notification is high as compare to measles which is 22.0 percent 100,000 population ,measles is profoundly find in region of New South Wales and Victoria ,where as pertussis more common in south Australia.

Measles is virus and serological methods use for diagnosis, in laboratory. On other hand, pertussis is bacterial in origin; measles is still difficult to test serologically in laboratory due to sensitivity and specificity of test. But it is not same for pertussis. The measles number of cases has continued to fall markedly after outbreak in 1993 and 1994, similarly rubella notification fell since 1996, but the number of pertussis case remained similar level to record as compare to recent records, the highest rate of incidence common in age below one years old, last peak of started from 1996 which has continued till 1997 to now.

 

 

Hence, strategy recommended after numerous surveillance requires supporting measles are:-

•1.    Revised control program is to target both for measles vaccination coverage, population susceptibility and measles control.

•2.    Serological testing (IgM) for suspected measles is defined as best diagnostic criteria and for referral of all positive sera from sporadic cases to reference laboratory for confirmation.

•3.    The use of active surveillance enhance to activity of routine surveillance procedure.

•4.    Uniform case studies and data collection will also include vaccination status of all age group population.

•5.    Enhanced surveillance method will help to notify adverse events of following immunisations.

•6.    Use of standard data is indicators to monitor of good quality surveillance.

•7.    National or state territory serological survey helps to monitor the effectiveness of the measles immunisation program and to study various changes to the MMR vaccination schedule.