Evaluation of Measles Case Based Surveillance System

Measles is a highly contagious serious respiratory viral disease characterized by fever, and maculopapular erythematous rash. Symptoms include fever, cough, coryza, conjunctivitis and generalized maculopapular erythematous rash. Measles infection can result in serious complications, including blindness, encephalitis, severe diarrhoea, ear infection or severe respiratory infections such as pneumonia. Measles is transmitted via droplets from the nose, mouth or throat of infected persons. Initial symptoms, which usually appear 10–12 days after infection, include high fever, a runny nose, bloodshot eyes, and tiny white spots on the inside of the mouth. Several days later, a rash develops, starting on the face and upper neck and gradually spreading downwards.

Measles transmission is dependent on several factors including population vaccination coverage rates. Individuals without a history of natural immunity or not successfully immunized against measles are considered to be at increased risk of acquiring measles. Measles complications disproportionately affect persons suffering from malnutrition, immunodeficiency and pregnant women. Severe measles is more likely among poorly nourished young children, especially those with insufficient vitamin A, or whose immune systems have been weakened by human immunodeficiency virus infection and acquired immune deficiency syndrome (HIV/AIDS) or other diseases. The most serious complications include blindness, encephalitis (an infection that causes brain swelling), severe diarrhoea and related dehydration, and severe respiratory infections such as pneumonia.

Despite the availability of a highly effective vaccine, measles remains the leading cause of vaccine-preventable deaths in the world, accounting for over 40% of the 1.4 million annual deaths due to vaccine-preventable diseases. Globally, 139,300 deaths were reported due to measles only in 2012. In developing countries particularly, Africa and Asia, measles is still common. An estimated 7 million people were affected by measles in 2016 globally. The overwhelming majority of more than 95% of measles deaths occur in countries with low per capita and health infrastructures. About 13 million cases, 650,000 deaths occur annually, with sub-Saharan Africa having the highest morbidity and mortality.
There is no specific antiviral treatment for measles virus. However severe complications from measles can be avoided through supportive care that ensures good nutrition, adequate fluid intake and treatment of dehydration with World health Organisation (WHO) recommended oral rehydration solution. All children diagnosed with measles should receive two doses of vitamin A supplements, given 24 hours apart. This treatment restores low vitamin A levels during measles that occur even in well-nourished children and can help prevent eye damage and blindness. Vitamin A supplements have been shown to reduce the number of deaths from measles by 50%. The best way in which measles can be prevented is through routine vaccination of children combined with mass immunization campaigns. The measles vaccine is often incorporated with rubella and/or mumps vaccines.

Countries began using measles vaccines in the 1960s. Prior to the availability of measles vaccine, measles infected over 90% of children before they reached 15 years of age. These infections were estimated to cause more than two million deaths and between 15 000 and 60 000 cases of blindness annually worldwide. Measles deaths decreased by 84 percent world-wide from 550,100 deaths in 2000 to 89,780 in 2016. Under the Global Vaccine Action Plan, measles is targeted for elimination in five WHO Regions by 2020.

Measles infection is endemic in Zimbabwe and has been documented to occur all year round, despite high measles routine and supplemental immunization coverage. Measles notification system is a case based surveillance system and has been in existence since 1998. The objectives of measles surveillance system are to identify at risk populations, to monitor the impact of routine and supplementary activities, to measure progress towards achieving elimination of measles and to monitor accumulation of susceptible and take appropriate actions.

Public health surveillance is the cornerstone of public health practice and can be defined as the systematic, ongoing collection, management, analysis, and interpretation of data followed by the dissemination of these data to public health programs to stimulate public health action. Measles notification system is a case based surveillance system and has been in existence since 1998. The objectives of measles surveillance system are to identify at risk populations, to monitor the impact of routine and supplementary activities, to measure progress towards achieving elimination of measles and to monitor accumulation of susceptible and take appropriate actions.
Measles surveillance systems use case definitions designed to standardize reporting across health facilities and at various levels of the health system – subnational, national and international. This facilitates aggregation, analysis and interpretation of data, as well as a comparison between geographical areas and over time. The case definitions for measles include the following categories: suspected, laboratory confirmed, epidemiologically linked, clinically compatible and discarded cases.

The clinical criteria for measles are:

- fever and
- maculopapular rash ( non-vesicular rash) and
- Cough or coryza (runny nose) or conjunctivitis (red eyes).
The laboratory criteria for measles surveillance case confirmation are:
- measles IgM antibody detection or
- measles virus isolation or
- measles viral RNA detection by RT-PCR or
- a significant rise in measles IgG antibody in paired sera.

Case category Definition
Suspected

A case with signs and symptoms consistent with clinical criteria of measles.
All suspected cases have to be investigated and classified based on clinical, laboratory and epidemiological data as one of the following:

Laboratory confirmed

A suspected case which meets the laboratory criteria for measles case confirmation.

Epidemiologically linked

A suspected case which has not been adequately tested by laboratory and which was in contact with a laboratory-confirmed measles case 7–18 days before the onset of rash.

Clinically compatible

A suspected case which has not been adequately tested by laboratory and has not been epidemiologically linked to a confirmed measles case.

Discarded

A suspected case which was investigated and discarded, either through negative results of adequate laboratory testing for measles or by an epidemiological link to a laboratory-confirmed case of another disease.

A timely surveillance and rapid case detection for measles followed by rapid outbreak response is key for control and elimination of measles and reducing number of cases, complications and related mortality.

Main Measles Surveillance Indicators:

i. Non measles febrile rash illness rate : (target : at least 2 per 100,000 population)

ii. Proportion of districts that have reported at least 1 suspected case of measles with a blood specimen per year: (Target: at least 80%)

Supplementary Indicators for Measles Surveillance

i. Proportion of reported suspected measles cases from whom blood specimens have been collected (exclude epidemiologically linked cases from the denominator): (Target: at least 80%)

ii. Timeliness of health facility IDS monthly reporting to the district level within the specified time period. (Target; at least 80% reports received timely at district level)

iii. Annualized rate of investigation (with blood specimens) of suspected measles cases (Target: > 1 case investigated with blood specimen / 100,000 population per year)

iv. Proportion of measles outbreaks investigated with blood specimens from the first five cases: (Target: at least 80% measles outbreaks investigated with blood specimens)

v. Proportion of measles outbreaks with specimens collected and documentation done on measles viral strains: (Target: at least 80% measles outbreaks with measles viral strains documented) viii. Timeliness of suspected measles case investigation: (Target: at least 80% investigated within 3 days following notification)

vi. Timeliness of serum/ dried blood specimens arriving at lab: (Target; at least 80% specimens arrived at lab within 3 days of being taken)

vii. Laboratory Indicators x. Timeliness of feedback of serology results from the laboratory to the national level: (Target: at least 80% results sent out by the lab to the national level within 7 days of receipt of specimens at the lab)

viii. Proportion of serum specimens arriving at the National measles laboratory in good condition (Target: at least 90% of specimens arriving at the laboratory in good condition; i.e., adequate volume, no leakage, not turbid, not desiccated)

ix. Proportion of representative serum specimens sent quarterly by the national laboratories to the regional reference labs for re-confirmation as part of quality assurance measures (Target: at least 10% of specimens tested at national lab shared with the RRL)

x. Proportion of concordance of measles IgM results between the national measles lab and the regional reference lab (Target; at least 90% concordance between results of shared specimens between the national lab and the RRL )1-5
The following indicators are used for monitoring measles surveillance :

Notification

• Suspected measles cases should be reported routinely on T5 forms and measles notification forms
• More than 88% of reports should come on time
• 80% or more of reporting sites are supposed to be reporting at least one suspected case per year
• More than 80% of cases should be reported within seven days of onset of rash.

Investigation

• 80% of suspected measles cases should be investigated within 48 hours of being reported
• 80% or more of serum specimen should get to the laboratory within three days of collection
• 80% or more of the results should be out within seven days of receipt in the laboratory.

Cite this page