Malaria Surveillance Indicators
Malaria Surveillance Indicators (Malareometric measurements)
In the pre-eradication era, the magnitude of the malaria problem in a country used to be determined mostly from the reports of the clinically diagnosed malaria cases and the classical malariometric measures, e.g., spleen rate, parasite rate etc.
On the other hand, during eradication era, the microscopic diagnosis of malaria cases became the main method of diagnosis and the parameters used are mostly parasitological in nature e.g., API, ABER, SPR and SFP
| Pre eradication era (based on clinical diagnosis of malaria) | Eradication Era (based on microscopic diagnosis of malaria) |
a) Spleen rate:
|
a) Annual Parasite Incidence = (API)
(Confirmed cases during one year/ population under surveillance) x 1000. It is the sophisticated measure of malaria incidence and burden of disease in a community. |
b) Average enlarged spleen:
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b) Annual Blood Examination Rate = (No. of slides examined population) x 100.
ABER is an index of operational efficiency. In the modified plan of operation, the minimum prescribed is 10 percent of the population in a year. |
| c) Parasite rate:
Defined as on the percentage of children between the ages of 2 & 10 yrs showing malarial parasites in their blood films. |
c) Annual falciparum incidence
Data is separately collected for P.falciparum |
| d) Parasite density index: Average degree of parasitemia in a sample of well defined group of population. Only positive slides are included in denominator | d) Slide positivity rate:
Slide positivity rate is the percentage of slides found positive for malarial parasite, irrespective of the type of species |
e) Infant parasite rate:
f) Proportional case rate: Its a crude index. It is defined as number of cases diagnosed as clinical malaria for every 100 patients attending the hospitals and dispensaries. |
e) Slide falciparum rate:
|
A malaria survey is not complete unless it includes investigations relating to the insect vector.
All these rates are employed in the quantitative assessment of malaria and in building up a composite epidemiological picture of malaria.
VECTOR INDICES
| (a) HUMAN BLOOD INDEX | It is the proportion of freshly fed female Anopheline mosquitoes whose stomach contains human blood. It indicates the degree of anthrophilism. |
| (b) SPOROZOITE RATE | It is the percentage of female anopheles with sporozoites in their salivary glands. |
| (c) MOSQUITO DENSITY: |
It is usually expressed as the number of mosquitoes per man-hour-catch. |
| (d) MAN-BITING RATE (Biting density) |
It is defined as the average incidence of anopheline bites per day per person. It is determined by standardized vector cache on human bait. |
| (e) INOCULATION RATE: | The man-biting rate multiplied by the infective sporozoite rate is called the inoculation rate. |
HIGH YIELD-MALAREOMETRIC MEASUREMENTS
- Pre eradication era-parameters are based on clinical diagnosis (Spleen Rate, Average enlarged spleen, Parasite rate, Parasite density index, Infant parasite rate and proportional case rate).
- Eradication era-parametes are based on microscopic diagnosis of malaria (Annual parasite incidence, Annual blood examination rate, Annual falciparum incidence, Slide positivity rate, Slide falciparum rate)
- Vector Indices are (Human blood index, Sporozoite rate, mosquito density, man biting rate and inoculation rate)
- Spleen rate is widely used for measuring the endemicity of malaria in a community
- Infant parasite rate is the most sensitive index of recent transmission of malaria in a locality.
- Annual parasite incidence is the sophisticated measure of malaria incidence and burden of disease in a community.
- Annual Blood Examination Rate is an index of operational efficiency.
- Human Blood Index indicates the degree of anthrophilism.
