Browsing by Author "Mugittu, Kefas"

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    Malaria prevalence in asymptomatic and symptomatic children in Kiwangwa, Bagamoyo district, Tanzania
    (Springer Nature, 2017-05-25) Sumari, Deborah; Mwingira, Felista; Majige, Selemani; Mugittu, Kefas; Mugasa, Joseph; Gwakisa, Paul
    Background Malaria prevalence continues to decline across sub-Saharan Africa as a result of various intervention strategies. However, the diseases still poses a public health concern in the region. While symptomatic malaria is recognized and treated, asymptomatic infections become increasingly important for interrupting transmission. A cross-sectional survey was conducted to assess malaria prevalence in symptomatic and asymptomatic children in Kiwangwa ward in Bagamoyo District in Tanzania. Methods Four hundred school-aged children in Kiwanga ward were recruited in the study; 200 from Kiwangwa dispensary and 200 from nearby schools. Primary health parameters were examined and blood samples collected and examined for Plasmodium falciparum prevalence using rapid diagnostic test (RDT), light microscopy (LM) and reverse transcription quantitative PCR (RT-qPCR) targeting transcripts of A-type 18s rRNA of P. falciparum. Gametocytes were detected by LM and RT-qPCR targeting transcripts of gametocyte specific marker, Pfs25. Results Overall P. falciparum prevalence was 73.3, 40.8 and 36.3% by RT-qPCR, RDT and LM in the study area, respectively (P < 0.001). As expected symptomatic children had a significantly higher prevalence of 89, 67.5 and 64.5% by qPCR, RDT and LM, compared to 57.5, 14 and 8% in the asymptomatic group, respectively. However, gametocyte prevalence in asymptomatic individuals was higher by both LM (2%) and qPCR (14%) than in symptomatic individuals LM (0.5%) and qPCR (3%). Conclusions A substantial difference in prevalence of symptomatic and asymptomatic infections observed in Kiwangwa ward underpins the use of molecular tools in malaria surveillance aiming at estimating prevalence and transmission. Notably, the higher gametocytaemia observed in asymptomatic children indicates the reservoir infections and points to the need for detection and treatment of both asymptomatic and symptomatic malaria.
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    Plasmodium falciparum msp1 , msp2 and glurp allele frequency and diversity in sub-Saharan Africa
    (Malaria Journal, 2011) Mwingira, Felista; Nkwengulila, Gamba; Schoepflin, Sonja; Sumari, Deborah; Beck, Hans-Peter; Snounou, Georges; Felger, Ingrid; Olliaro, Piero; Mugittu, Kefas
    Background: The efficacy of anti-malarial drugs is assessed over a period of 28-63 days (depending on the drugs’ residence time) following initiation of treatment in order to capture late failures. However, prolonged follow-up increases the likelihood of new infections depending on transmission intensity. Therefore, molecular genotyping of highly polymorphic regions of Plasmodium falciparum msp1, msp2 and glurp loci is usually carried out to distinguish recrudescence (true failures) from new infections. This tool has now been adopted as an integral part of anti-malarial efficacy studies and clinical trials. However, there are concerns over its utility and reliability because conclusions drawn from molecular typing depend on the genetic profile of the respective parasite populations, but this profile is not systematically documented in most endemic areas. This study presents the genetic diversity of P. falciparum msp1, msp2 and glurp markers in selected sub-Saharan Africa countries with varying levels of endemicity namely Malawi, Tanzania, Uganda, Burkina Faso and São Tomé. Methods: A total 780 baseline (Day 0) blood samples from children less than seven years, recruited in a randomized controlled clinical trials done between 1996 and 2000 were genotyped. DNA was extracted; allelic frequency and diversity were investigated by PCR followed by capillary electrophoresis for msp2 and fragment sizing by a digitalized gel imager for msp1 and glurp. Results and Conclusion: Plasmodium falciparum msp1, msp2 and glurp markers were highly polymorphic with low allele frequencies. A total of 17 msp1 genotypes [eight MAD20-, one RO33- and eight K1-types]; 116 msp2 genotypes [83 3D7 and 33 FC27- types] and 14 glurp genotypes were recorded. All five sites recorded very high expected heterozygosity (HE) values (0.68 - 0.99). HE was highest in msp2 locus (HE = 0.99), and lowest for msp1 (HE = 0.68) (P < 0.0001). The genetic diversity and allelic frequency recorded were independent of transmission intensity (P = 0.84, P = 0.25 respectively. A few genotypes had particularly high frequencies; however the most abundant showed only a 4% probability that a new infection would share the same genotype as the baseline infection. This is unlikely to confound the distinction of recrudescence from new infection, particularly if more than one marker is used for genotyping. Hence, this study supports the use of msp1, msp2 and glurp in malaria clinical trials in sub-Saharan Africa to discriminate new from recrudescent infections.
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    Plasmodium Falciparum Msp1, Msp2 And Glurp Allele Frequency and Diversity in Sub-Saharan Africa
    (BioMed Central, 2011) Mwingira, Felista; Nkwengulila, Gamba; Schoepflin, Sonja; Sumari, Deborah; Beck, Hans-Peter; Snounou, Georges; Felger, Ingrid; Olliaro, Piero; Mugittu, Kefas
    The efficacy of anti-malarial drugs is assessed over a period of 28-63 days (depending on the drugs’ residence time) following initiation of treatment in order to capture late failures. However, prolonged follow-up increases the likelihood of new infections depending on transmission intensity. Therefore, molecular genotyping of highly polymorphic regions of Plasmodium falciparum msp1, msp2 and glurp loci is usually carried out to distinguish recrudescence (true failures) from new infections. This tool has now been adopted as an integral part of anti-malarial efficacy studies and clinical trials. However, there are concerns over its utility and reliability because conclusions drawn from molecular typing depend on the genetic profile of the respective parasite populations, but this profile is not systematically documented in most endemic areas. This study presents the genetic diversity of P. falciparum msp1, msp2 and glurp markers in selected sub-Saharan Africa countries with varying levels of endemicity namely Malawi, Tanzania, Uganda, Burkina Faso and São Tomé. A total 780 baseline (Day 0) blood samples from children less than seven years, recruited in a randomized controlled clinical trials done between 1996 and 2000 were genotyped. DNA was extracted; allelic frequency and diversity were investigated by PCR followed by capillary electrophoresis for msp2 and fragment sizing by a digitalized gel imager for msp1 and glurp. Plasmodium falciparum msp1, msp2 and glurp markers were highly polymorphic with low allele frequencies. A total of 17 msp1 genotypes [eight MAD20-, one RO33- and eight K1-types]; 116 msp2 genotypes [83 3D7 and 33 FC27- types] and 14 glurp genotypes were recorded. All five sites recorded very high expected heterozygosity (HE) values (0.68 - 0.99). HE was highest in msp2 locus (HE = 0.99), and lowest for msp1 (HE = 0.68) (P < 0.0001). The genetic diversity and allelic frequency recorded were independent of transmission intensity (P = 0.84, P = 0.25 respectively. A few genotypes had particularly high frequencies; however the most abundant showed only a 4% probability that a new infection would share the same genotype as the baseline infection. This is unlikely to confound the distinction of recrudescence from new infection, particularly if more than one marker is used for genotyping. Hence, this study supports the use of msp1, msp2 and glurp in malaria clinical trials in sub-Saharan Africa to discriminate new from recrudescent infections.