Surveillance in Finding Malaria Cases
Surveillance can be active or passive. In active surveillance, specific workers designated as surveillance workers are given target areas that they are supposed to visit once a fortnight. They enquire the following:

1. Whether there is a case of fever in the house.
2. Whether there was one between his previous visit and the present one.

If the answer to either of these two questions is “Yes”, the surveillance worker collects a blood film (thick and thin on the same slide) and administers a single dose (600 mg for an adult and proportionate doses for others) of chloroquin according to the prescribed NMEP schedule. This is a known “Presumptive treatment”. The surveillance worker makes necessary entries in the stencil or house card about his visit and dispatches the blood slides at least twice a week to the unit laboratory (primary health center) for microscopic examination.

Passive surveillance
The search for malaria cases by local health agencies such as primary health centers, sub–centers, hospitals, dispensaries and local medical practitioners is known as “Passive surveillance”. The passive agencies collect blood smears from all fever cases and also from those with a history of recent fever.