Browsing by Subject "Vectors"

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    A brief history of marine bio-invasions in South Africa
    (2009) Griffiths, C L; Mead, A; Robinson, T B
    Marine species have been introduced continuously into South Africa for more than 400 years, since the arrival of the first European explorers. Various waves of introduction can be identified over this period, each associated with a different mix of vectors. Early wooden vessels carried specialized wood-boring species, a rich external fouling community, plus semi-terrestrial species associated with dry ballast. Modern steel vessels continue to import fouling species, despite the use of anti-fouling paints, and may ply new routes, bringing additional introductions from novel locations. More modern waves of introduction are associated with use of ballast water and with marine aquaculture. Research on marine bio-invasions in South Africa has a short history, marked by a rapid rate of discovery of introductions. Some 86 marine species are currently regarded as introduced to the region, with a further 39 considered cryptogenic, but this number is increasing rapidly. Moreover, many taxa and regions still remain inadequately explored, indicating that the current list remains far from complete. The reasons for under-reporting of introduced populations are discussed and include lack of sample coverage, misidentification of aliens as native species and erroneous redescriptions of aliens as new, indigenous species. However, the lack of taxonomic expertise across large sections of the biota remains the greatest impediment to progress.
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    Gametocyte carriage in uncomplicated Plasmodium falciparum malaria following treatment with artemisinin combination therapy: a systematic review and meta-analysis of individual patient data
    (2016)
    : Gametocytes are responsible for transmission of malaria from human to mosquito. Artemisinin combination therapy (ACT) reduces post-treatment gametocyte carriage, dependent upon host, parasite and pharmacodynamic factors. The gametocytocidal properties of antimalarial drugs are important for malaria elimination efforts. An individual patient clinical data meta-analysis was undertaken to identify the determinants of gametocyte carriage and the comparative effects of four ACTs: artemether-lumefantrine (AL), artesunate/amodiaquine (AS-AQ), artesunate/mefloquine (AS-MQ), and dihydroartemisinin-piperaquine (DP). : Factors associated with gametocytaemia prior to, and following, ACT treatment were identified in multivariable logistic or Cox regression analysis with random effects. All relevant studies were identified through a systematic review of PubMed. Risk of bias was evaluated based on study design, methodology, and missing data. : The systematic review identified 169 published and 9 unpublished studies, 126 of which were shared with the WorldWide Antimalarial Resistance Network (WWARN) and 121 trials including 48,840 patients were included in the analysis. Prevalence of gametocytaemia by microscopy at enrolment was 12.1 % (5887/48,589), and increased with decreasing age, decreasing asexual parasite density and decreasing haemoglobin concentration, and was higher in patients without fever at presentation. After ACT treatment, gametocytaemia appeared in 1.9 % (95 % CI, 1.7-2.1) of patients. The appearance of gametocytaemia was lowest after AS-MQ and AL and significantly higher after DP (adjusted hazard ratio (AHR), 2.03; 95 % CI, 1.24-3.12; P = 0.005 compared to AL) and AS-AQ fixed dose combination (FDC) (AHR, 4.01; 95 % CI, 2.40-6.72; P < 0.001 compared to AL). Among individuals who had gametocytaemia before treatment, gametocytaemia clearance was significantly faster with AS-MQ (AHR, 1.26; 95 % CI, 1.00-1.60; P = 0.054) and slower with DP (AHR, 0.74; 95 % CI, 0.63-0.88; P = 0.001) compared to AL. Both recrudescent (adjusted odds ratio (AOR), 9.05; 95 % CI, 3.74-21.90; P < 0.001) and new (AOR, 3.03; 95 % CI, 1.66-5.54; P < 0.001) infections with asexual-stage parasites were strongly associated with development of gametocytaemia after day 7. : AS-MQ and AL are more effective than DP and AS-AQ FDC in preventing gametocytaemia shortly after treatment, suggesting that the non-artemisinin partner drug or the timing of artemisinin dosing are important determinants of post-treatment gametocyte dynamics.