SOP – Malaria Microscopy - NVBDCP

Quality Assurance of Malaria Diagnostic testsFungusWill show up as artifacts on blood film. The best way to prevent fungal growths on slides is tostain blood films as soon as possible after preparation and drying them- within 48 hours atmost.Other contaminantsDust particles floating in the air will settle on blood films while they are drying either before orafter staining. Specks of dirt may be transferred from a patient’s finger when a blood sampleis taken or the original slide may not be perfectly clean. Some artifacts are shown in Figure9.8.3.8 Estimation of parasite density8.3.8.1 Determination of parasite density in thick film• using the 40x objective, select a part of the film that is well stained, free of stainingdebris and well populated with white blood cells. A well made film of even thicknessis ideal for determining parasite density.• place the immersion oil on the thick film.• swivel the 100x oil immersion objective over the selected portion of blood film.• confirm that the portion of film selected is acceptable and continue to examine theslide for 100 oil immersion fields. Move the blood film by one oil immersion field eachtime, following the pattern described by thin film.• use a tally counter to count the fields as they are examined. For counting of parasitedensity by following the methods described below:8.3.8.2 Counting of the parasiteIt is necessary to establish a parasite count for the blood film for the following reasons:• parasite counts are especially important in P. falciparum infections which arepotentially fatal:to know the severity of malaria.for special purposes, such as testing the sensitivity of parasites toantimalarial drugs. to know the response of the malaria parasites to the anti malarialtreatment being given. This can be monitored over time by plotting theparasite count on the day of treatment and comparing it with the count in ablood film made at some specified time later.• Besides, parasite count is very essential for preparation of QC/EQA samplesto be used for testing malaria RDTs. Prior to preparation of QC/EQA samples,it is recommended to pre-qualify LTs to be utilized in the field to ensureaccuracy of subsequent parasite count.Parasite count should not start until examination of 100-field is completed and the parasitespecies and stages present are identified. Two methods are used to establish the parasitecount as earlier.SOP – Malaria Microscopy© Copyright to Dte. NVBDCP Only. Any modification are prohibited