University:
University of Cincinnati Blue Ash
Course:
BIOL 5180 | Immunology
Academic year:

2024
Views:

439

Pages:

3
Author:

Jasper J.

Parasitemia Examination 1. Thick Blood Smear a. Semi Quantitative Method or Plus System This method is a simple method aimed at counting parasites in thick blood smears. However, this method is considered unsatisfactory and is only carried out if calculations using quantitative methods are not possible. (-) : negative if no parasites are found in 100 LPB (+) : Positive 1 (found 1-10 parasites in 100 LPB) (++) : Positive 2 (found 11-100 parasites in 100 LPB) (+++) : Positive 3 (1-10 parasites found in 1 LPB) (++++) : Positive 4 (found > 10 parasites in 1 LPB) Notes: - Count asexual and sexual forms of parasites separately - A blood smear is said to be negative if it has been examined from at least 200 fields of view with an objective lens magnification of 100x. b. Quantitative Methods - The number of parasites per microliter of blood was calculated based on the number of leukocytes (8000/µl) in a thick blood smear. To calculate parasites, 2 taily counters are required. One for counting parasites, and the other for counting leukocytes. - If 10 or more parasites are found in 200 leukocytes, record the results per 200 leukocytes. - If only 9 parasites or less are found in 200 leukocytes, then continue the examination to 500 leukocytes, record the results per 500 leukocytes. - Count the number of leukocytes in 1 µl of blood: Example: If it is found in a thick blood film that there are 1500 parasites per 200 leukocytes, what is the parasitemia count in a thick blood film? Calculate parasitemia = (1500/200) x 8000 leukocytes/ µl = 60,000 parasites/ µl blood 2. Thin Blood Smear Preparation Calculate the percentage of infected erythrocytes if falciparum malaria is found with high parasitemia. This examination can be used to assess the response to therapy in malaria sufferers. The calculation can be done in the following way: (Number of infected erythrocytes / 1000) x 100% = % Example: - If found in a thin blood smear there are 50 infected erythrocytes per 1000 erythrocytes, then the percentage of parasitemia is (50 / 1000) x 100% = 5% This examination can also be continued by determining the number of parasite infections per µl of blood in a thin blood smear. (AE / 1000) X number of erythrocytes infected with parasites =............ parasites/ µl blood The AE value is 450,000/ µl blood If 50 infected erythrocytes are found, the parasite count per µl of blood is as follows: (450,000/1000) x 50 = 22,500 parasites/ µl of blood Notes: For people with suspected severe malaria, you need to pay attention to the following things: - If the first blood test is negative, it needs to be repeated every 6 hours for up to 3 consecutive days - If a thick blood test after 3 consecutive days does not reveal parasites, the diagnosis of malaria can be ruled out.