Browsing by Author "Ocan, Moses"

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    Incomplete reversal of genotypic resistance of Plasmodium falciparum to chloroquine after a decade of change in malaria treatment policy in Uganda
    (Reports in Parasitology, 2016) Ocan, Moses; Katabazi, Fred A; Kigozi, Edgar.; Bwanga, Freddie.; Kyobe, Samuel.; Ogwal-Okeng, Jasper; Obua, Celestino.
    Background: The potential re-emergence of Plasmodium falciparum parasites sensitive to chloroquine provides an opportunity for the reintroduction of the drug in patient care. With the recent discovery and spread of artemisinin resistance in South east Asia, the emergence of chloroquine sensitivity gives hope for malaria treatment globally. In this study, we explored the prevalence of genotypic chloroquine resistant P. falciparum isolates collected from symptomatic patients in northern Uganda. Methods: Finger-prick capillary blood spotted on Whatman 903 filter papers were collected from adult symptomatic outpatients ($18 years) in Lira and Gulu regional referral hospitals. Patients were screened for the presence of Plasmodium infection using rapid diagnostic test histidine rich protein-2 (HRP- 2) prior to blood sample collection. Parasite DNA was extracted from individual spots on the filter papers using chelex-resin method. Presence of mutations, Pfcrt K76T and Pfmdr N86Y were analyzed using polymerase chain reaction-restriction fragment length polymorphism (RFLP) method. A total of 213 and 169 amplicons were analyzed for Pfcrt K76T and Pfmdr N86Y polymorphisms, respectively. The data were analyzed in an Excel 2007 spreadsheet. Results: A total of 89/213 (41.8%) of the P. falciparum isolates analyzed for Pfcrt K76T polymorphism had wild type (chloroquine sensitive) genotype (76K). The majority, 116/213 (54.4%) carried the mutant (chloroquine resistant) genotype 76T whereas 8/213 (3.8%) had mixed genotypes Pfcrt-76K/T (sensitive/resistant). For Pfmdr N86Y polymorphisms, the majority, 164/169 (97%) of the isolates had wild type (chloroquine sensitive) genotype Pfmdr 86N. A small proportion, (3/169) 1.8% had mutant (chloroquine resistant) genotype Pfmdr 86Y, whereas 2/169 (1.2%) samples had mixed genotypes Pfmdr1-86N/Y (sensitive/resistant). Conclusion: P. falciparum parasites with genotypic resistance to chloroquine have persisted in the population after more than a decade since the change of policy in Uganda.
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    Prevalence of K13-propeller gene polymorphisms among Plasmodium falciparum parasites isolated from adult symptomatic patients in northern Uganda
    (BioMed Central, 2016) Ocan, Moses; Bwanga, Freddie; Okeng, Alfred; Katabazi, Fred; Kigozi, Edgar; Kyobe, Samuel; Ogwal-Okeng, Jasper; Obua, Celestino
    Background: In the absence of an effective vaccine, malaria treatment and eradication is still a challenge in most endemic areas globally. This is especially the case with the current reported emergence of resistance to artemisinin agents in Southeast Asia. This study therefore explored the prevalence of K13-propeller gene polymorphisms among Plasmodium falciparum parasites in northern Uganda. Methods: Adult patients (≥18 years) presenting to out-patients department of Lira and Gulu regional referral hospitals in northern Uganda were randomly recruited. Laboratory investigation for presence of plasmodium infection among patients was done using Plasmodium falciparum exclusive rapid diagnostic test, histidine rich protein-2 (HRP2) (Pf). Finger prick capillary blood from patients with a positive malaria test was spotted on a filter paper Whatman no. 903. The parasite DNA was extracted using chelex resin method and sequenced for mutations in K13-propeller gene using Sanger sequencing. PCR DNA sequence products were analyzed using in DNAsp 5.10.01software, data was further processed in Excel spreadsheet 2007. Results: A total of 60 parasite DNA samples were sequenced. Polymorphisms in the K13-propeller gene were detected in four (4) of the 60 parasite DNA samples sequenced. A non-synonymous polymorphism at codon 533 previously detected in Cambodia was found in the parasite DNA samples analyzed. Polymorphisms at codon 522 (non-synonymous) and codon 509 (synonymous) were also found in the samples analyzed. The study found evidence of positive selection in the Plasmodium falciparum population in northern Uganda (Tajima’s D=−1.83205; Fu and Li’s D=−1.82458). Conclusions: Polymorphism in the K13-propeller gene previously reported in Cambodia has been found in the Ugandan Plasmodium falciparum parasites. There is need for continuous surveillance for artemisinin resistance gene markers in the country.