| Autor: |
Potlapalli V; Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA., Muller MS; Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA., Ngasala B; Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania., Ali IM; Department of Biochemistry, Faculty of Science, University of Dschang, Dschang, Cameroon., Na YB; Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA., Williams DR; Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC USA., Kharabora O; Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA., Chhetri S; Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA., Liu MS; Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA., Carey-Ewend K; Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC USA., Lin FC; Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC USA., Mathias D; Florida Medical Entomology Laboratory, Institute of Food & Agricultural Sciences, University of Florida, Vero Beach, FL USA., Tarimo BB; Vector Immunity and Transmission Biology Unit, Department of Environmental Health and Ecological Sciences, Ifakara Health Institute-Bagamoyo Office, Bagamoyo, Tanzania., Juliano JJ; Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA.; Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC USA., Parr J; Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA., Lin JT; Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA. |
| Abstrakt: |
Plasmodium ovale curtisi (Poc) and Plasmodium ovale wallikeri (Pow) represent distinct non-recombining malaria species that are increasing in prevalence in sub-Saharan Africa. Though they circulate sympatrically, co-infection within human and mosquito hosts has rarely been described. Separate 18S rRNA real-time PCR assays that detect Poc and Pow were modified to allow species determination in parallel under identical cycling conditions. The lower limit of detection was 0.6 plasmid copies/μL (95% CI 0.4-1.6) for Poc and 4.5 plasmid copies/μL (95% CI( 2.7- 18) for Pow , or 0.1 and 0.8 parasites/μL, respectively, assuming 6 copies of 18s rRNA per genome. However, the assays showed cross-reactivity at concentrations greater than 10 3 plasmid copies/μL (roughly 200 parasites/μL). Mock mixtures were used to establish criteria for classifying mixed Poc/Pow infections that prevented false-positive detection while maintaining sensitive detection of the minority ovale species down to 10° copies/μL (<1 parasite/μL). When the modified real-time PCR assays were applied to field-collected blood samples from Tanzania and Cameroon, species identification by real-time PCR was concordant with nested PCR, but additionally detected two mixed Poc/Pow infections where nested PCR detected a single Po species. When real-time PCR was applied to 14 oocyst-positive Anopheles midguts saved from mosquitoes fed on P. ovate -infected persons, mixed Poc/Pow infections were detected in 11 (79%). Based on these results, 8/9 P. ovate carriers transmitted both P. ovate species to mosquitoes, though both Po species could only be detected in the blood of two carriers. The described real-time PCR approach can be used to identify the natural occurrence of mixed Poc/Pow infections in human and mosquito hosts and reveals that such co-infections and co-transmission are likely more common than appreciated. |
