COMPARISON OF CAPILLARY AND VENOUS BLOOD IN DETECTION OF MALARIA PARASITEMIA AMONG CHILDREN ATTENDING SELECTED HEALTH FACILITIES IN IBADAN, OYO STATE

Abstract

Malaria is a life-threatening disease caused by parasites that are transmitted to people through bite of infected female Anopheles mosquitoes. In order to eradicate the disease and avoid complications that may arise from severe infection, there is need to improve in management. Current diagnostic method requires testing blood samples which are commonly prepared using capillary or venous blood. However, it is unclear whether capillary or venous blood samples provide better diagnostic performance among children in Nigeria. This study aimed at comparing capillary and venous blood using RDT and microscopy in detection of malaria parasitemia in children attending selected health facilities in Ibadan, Oyo State, Nigeria. A comparative cross-sectional study was conducted from November 2019 to June 2020 among 286 children, ages 6 months to 15 years old recruited by convenience from two selected Local Government Areas in Ibadan. A pre-tested structured interviewer administered questionnaire was used to collect information on the social demographic characteristics, information on child’s health, malaria management and laboratory investigation results. Both venous and capillary blood samples were taken from the same child, and were examined using rapid diagnostic test and microscopy of stained thick and thin blood films. Descriptive statistics such as frequency, percentage, were used to summarize categorical variables while mean, standard deviation and range were used for continuous variables. Measures of performance such as Sensitivity, specificity, predictive value were used to determine validity; measure of accuracy, Chi-square was used to test significance in differences in performance of RDT and microscopy using capillary and venous blood. Factors associated with parasitaemia using both blood samples for RDT and microscopy was also examined. Level of significance was set at 5%. Mean age of the children was 5.7 ± 3.9 S.D, 178(62.2%) of the 286 enrolled were males. One hundred and two presented with fever and 21 patients have used antimalarial drug two weeks prior to presentation. Using capillary blood, 76 (26.6%) were positive for RDT and 88 (30.8%) for Microscopy (x²=250.38, p= < 0.001). From the venous blood, 76 (26.6%) were positive for RDT and 92 (32.2%) for microscopy (x²=256.08, p=<0.001.). Comparing capillary and venous blood when used for RDT, both gave the same proportion of parasitemia (n=76; 26.6%). Comparing capillary and venous blood when used for microscopy, venous blood gave a higher proportion of parasitaemia (n=92; 32.2%) than capillary blood (n= 88, 30.8%) [x²=132.02, P=<0.001). The sensitivity, specificity, NPV and PPV of RDT using capillary blood with microscopy as gold standard were 93.4%. 71.5%, 88.1%, and 82.9% respectively. The sensitivity, specificity, NPV and PPV of RDT using venous blood with microscopy as gold standard were 94.8%, 71.7%, 87.7%, and 86.8 % respectively. Accuracy for RDT using capillary blood or venous blood was 86.8% and 87.5% respectively. Having a high temperature was the only factor associated with parasitemia positivity for both capillary and venous blood when used for RDT and microscopy. (p<0.05). This study showed significant difference in malaria parasite detection between capillary and venous blood using microscopy while malaria detection between venous and capillary using RDT were similar. However, microscopy was more sensitive than RDT in both venous and capillary blood. Therefore, the use of capillary blood is advised for detection of malaria in children, a material which can be easily obtained by less invasive methods, for both RDT and microscopy.