Abstract:

To evaluate the diagnostic capacity of malaria by microscopy at primary medical and health institutions in Chongqing, four technicians for malaria diagnosis by microscopy were randomly selected from each of the 39 districts (counties) in Chongqing from March 2014 to December 2017 for assessment of their diagnostic capability. The test results underwent descriptive statistical analysis, correlation analysis, spatial autocorrelation analysis and ROC curve analysis. The average score of the 156 microscopy technicians was 4.33 ± 0.47, and among them the number of technicians who made one slide error on species determination was found the highest (75, 48.1%). The microscopic sensitivity was highest in qualitative diagnosis (98.9%), and lowest (15.9%) for Plasmodium ovale; the specificity was highest in the diagnosis of P. ovale (96.2%), and lowest for P. vivax (77.2%). The Youden index of different species was highest for P. falciparum (0.682 6), and lowest for P. ovale (0.121 4). The assessment score was positively correlated with the level of institutions technicians worked in (R = 0.21, P < 0.01), and negatively correlated with age (R = -0.31, P < 0.01). The average score was highest in Shapingba District and Wuxi County (4.88 points for each). The scores of the districts and counties showed a pattern of spatial aggregation (P < 0.01). The score was highest in the main urban area (4.51), and lowest in the central part of Yuzhong (4.08). There was a statistically significant difference in the score among geographical areas (P < 0.05). The areas under the ROC curve for species determination for P. falciparum, P. vivax and P. ovale was 0.97, 0.84, 0.78 and 0.56, respectively. The comparison of ROC curves showed that the efficiency of microscopic diagnosis of P. falciparum was significantly higher than those of other species (P < 0.01), and the efficiency of diagnosis of P. ovale was significantly lower than those of other species (P < 0.01). The results suggested that the technicians of microscopy at primary health institutions in Chongqing Municipality had good performance in qualitative diagnosis, but did not do well in Plasmodium species identification. The malaria diagnostic capacity of microscopy at town-level health institutions in the central areas of Chongqing was weaker than those in other areas.

Key words: Malaria, Assessment of diagnostic capacity by microscopy, Plasmodium species identification, Chongqing Municipality