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Background: Malaria is an infectious disease considered as one of the biggest causes of mortality in endemic areas. This life-threatening disease needs to be quickly diagnosed and treated. The standard diagnostic tools recommended by the World Health Organization are thick blood smears microscopy and immuno-chromatographic rapid diagnostic tests. However, these methods lack sensitivity especially in cases of low parasitaemia and non-falciparum infections. Therefore, the need for more accurate and reliable diagnostic tools, such as real-time polymerase chain reaction based methods which have proven greater sensitivity particularly in the screening of malaria, is prominent. This study was conducted at the French National Malaria Reference Centre to assess sensitivity and specificity of two commercial malaria qPCR kits and two in-house developed qPCRs compared to LAMP., Methods: 183 blood samples received for expertise at the FNMRC were included in this study and were subjected to four different qPCR methods: the Biosynex Ampliquick ® Malaria test, the BioEvolution Plasmodium Typage test, the in-house HRM and the in-house TaqMan qPCRs. The specificity and sensitivity of each method and their confidence intervals were determined with the LAMP-based assay Alethia® Malaria as the reference for malaria diagnosis. The accuracy of species diagnosis of the Ampliquick ® Malaria test and the two in-house qPCRs was also evaluated using the BioEvolution Plasmodium Typage test as the reference method for species identification., Results: The main results showed that when compared to LAMP, a test with excellent diagnostic performances, the two in-house developed qPCRs were the most sensitive (sensitivity at 100% for the in-house TaqMan qPCR and 98.1% for the in-house HRM qPCR), followed by the two commercial kits: the Biosynex Ampliquick ® Malaria test (sensitivity at 97.2%) and the BioEvolution Plasmodium Typage (sensitivity at 95.4%). Additionally, with the in-house qPCRs we were able to confirm a Plasmodium falciparum infection in microscopically negative samples that were not detected by commercial qPCR kits. This demonstrates that the var genes of P. falciparum used in these in-house qPCRs are more reliable targets than the 18S sRNA commonly used in most of the developed qPCR methods for malaria diagnosis., Conclusion: Overall, these results accentuate the role molecular methods could play in the screening of malaria. This may represent a helpful tool for other laboratories looking to implement molecular diagnosis methods in their routine analysis, which could be essential for the detection and treatment of malaria carriers and even for the eradication of this disease., (© 2022. The Author(s).)

The in vitro activities of 25 quinolones and fluoroquinolones against erythrocytic stages of Plasmodium falciparum and against liver stages of Plasmodium yoelii yoelii and P. falciparum were studied. All compounds were inhibitory for chloroquine-sensitive and chloroquine-resistant P. falciparum grown in red blood cells. This inhibitory effect increased with prolonged incubation and according to the logarithm of the drug concentration. Grepafloxacin, trovafloxacin, and ciprofloxacin were the most effective drugs, with 50% inhibitory concentrations of <10 micro g/ml against both strains. Only grepafloxacin, piromidic acid, and trovafloxacin had an inhibitory effect against hepatic stages of P. falciparum and P. yoelii yoelii; this effect combined reductions of the numbers and the sizes of schizonts in treated cultures. Thus, quinolones have a potential for treatment or prevention of malaria through their unique antiparasitic effect against erythrocytic and hepatic stages of Plasmodium.

We report in this work a highly sensitive and nonradioactive PCR method for the detection of the four species of parasite causing human malaria. Plasmodium-specific primers corresponding to the small-subunit rRNA genes of the malaria parasite were used, and a 291-bp fragment was amplified. Our results showed a high specificity for the four human Plasmodium species, and we were able to detect one parasite in 50 microl of whole blood. The responses of 12 patients infected with Plasmodium falciparum to antimalarial therapy were monitored by PCR diagnosis and examination of thick blood film for at least 20 min by an experienced microscopist. For one patient this study allowed early diagnosis of therapeutic failure, confirmed 7 days later by examination of the thick blood film. A total of 134 samples were examined; 94 were positive by PCR, and among these 68 were positive by thick blood film examination. The sensitivity of the thick blood film was 72.3% compared to PCR and 60.7% compared to dot blot hybridization.