Browsing by Author "Bock, Ronnie"

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    Evaluation of loop‑mediated isothermal amplification as a surveillance tool for malaria in reactive case detection moving towards elimination
    (2018) Tambo, Munyaradzi; Auala, Joyce R.; Sturrock, Hugh J.; Kleinschmidt, Immo; Bock, Ronnie; Smith, Jennifer L.; Gosling, Roland; Mumbengegwi, Davis R.
    Background: As malaria transmission decreases, the proportion of infections that are asymptomatic at any given time increases. This poses a challenge for diagnosis as routinely used rapid diagnostic tests (RDTs) miss asymptomatic malaria cases with low parasite densities due to poor sensitivity. Yet, asymptomatic infections can contribute to onward transmission of malaria and therefore act as infectious reservoirs and perpetuate malaria transmission. This study compared the performance of RDTs to loop-mediated isothermal amplification (LAMP) in the diagnosis of malaria during reactive active case detection surveillance. Methods: All reported malaria cases in the Engela Health District of Namibia were traced back to their place of residence and persons living within the four closest neighbouring houses to the index case (neighbourhood) were tested for malaria infection with RDTs and dried blood spots (DBS) were collected. LAMP and nested PCR (nPCR) were carried out on all RDTs and DBS. The same procedure was followed in randomly selected control neighbourhoods. Results: Some 3151 individuals were tested by RDT, LAMP and nPCR. Sensitivity of RDTs and LAMP were 9.30 and 95.50%, respectively, and specificities were 99.27 and 99.92%, respectively, compared to nPCR. LAMP carried out on collected RDTs showed a sensitivity and specificity of 95.35 and 99.85% compared to nPCR carried out on DBS. There were 2 RDT samples that were negative by LAMP but the corresponding DBS samples were positive by PCR. Conclusion: The study showed that LAMP had the equivalent performance as nPCR for the identification of Plasmodium falciparum infection. Given its relative simplicity to implement over more complex and time-consuming methods, such as PCR, LAMP is particularly useful in elimination settings where high sensitivity and ease of operation are important.
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    Medicinal value of Aptosimum albomarginatum (Marloth and Engl.), Albizia anthelmintica (A. Rich Brongn.) and Dicoma schinzii (O. Hoffm.) to a small community living at Gochas, southern Namibia
    (2017) Walter, Sunette; Beukes, Mervyn; Mumbengegwi, Davis R.; Bock, Ronnie
    Traditional medicine is widely used, but its effectiveness is often questioned. Biofilm-producing bacteria and fungi are important in difficult-to-treat persistent and recurrent infections. The present study investigated the anti-biofilm properties of crude methanolic extracts from three medicinal plants used in Namibia, namely Aptosimum albomarginatum (Marloth and Engl.), Albizia anthelmintica (A. Rich Brongn.) and Dicoma schinzii (O. Hoffm.). Biofilm formation, inhibition and eradication were determined using microtiter plate assay. Extracts were tested against Escherichia coli ATCC 700928, Staphylococcus aureus ATCC 12600, S. aureus U3300, Bacillus subtilis ATCC 13933, Streptococcus mutans ATCC 25175, Streptococcus sanguinis ATCC 10556, Pseudomonas aeruginosa and Candida albicans. All isolates were strong biofilm producers. A. albomarginatum root extract moderately inhibited biofilm formation in S. mutans ATCC 25175 (60.0%), E. coli ATCC 700928 (51.6%) and P. aeruginosa (49.1%). A. anthelmintica twigs caused 58.4% biofilm inhibition in C. albicans and eradicated S. aureus U3300 biofilm by 74.8%. D. schinzii leaf extract inhibited P. aeruginosa biofilm by 67.3%, and in addition broke down S. mutans ATCC 25175 biofilm by 44.2%. These results validate the usefulness of the three plants as traditional medicine in some instances.
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    Molecular detection of P. vivax and P. ovale foci of infection in asymptomatic and symptomatic children in Northern Namibia
    (2019) Haiyambo, Daniel H.; Uusiku, Petrina; Mumbengegwi, Davis R.; Pernica, Jeff M.; Bock, Ronnie; Malleret, Benoit; Renia, Laurent; Greco, Beatrice; Quaye, Isaac K.
    Knowledge of the foci of plasmodium species infections is critical for a country with an elimination agenda. Namibia is targeting malaria elimination by 2020. To support decision making regarding targeted intervention, we examined for the first time, the foci of Plasmodium species infections and regional prevalence in northern Namibia, using nested and quantitative polymerase chain PRC methods.