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We consider a stage-structured model of a harvested fish population and we are interested in the problem of estimating the
unknown stock state for each class. The model used in this work to describe the dynamical evolution of the population is a
discrete time system including a nonlinear recruitment relationship. To estimate the stock state, we build an observer for
the considered fish model. This observer is an auxiliary dynamical system that uses the catch data over each time interval
and gives a dynamical estimate of the stock state for each stage class. The observer works well even if the recruitment function
in the considered model is not well known. The same problem for an age-structured model has been addressed in a previous work
(Ngom et al., Math. Biosci. Eng. 5(2):337–354, 2008). 相似文献
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Safiatou Doumbo Tuan M. Tran Jules Sangala Shanping Li Didier Doumtabe Younoussou Kone Abdrahamane Traoré Aboudramane Bathily Nafomon Sogoba Michel E. Coulibaly Chiung-Yu Huang Aissata Ongoiba Kassoum Kayentao Mouctar Diallo Zongo Dramane Thomas B. Nutman Peter D. Crompton Ogobara Doumbo Boubacar Traore 《PLoS neglected tropical diseases》2014,8(9)
Background
Malaria and schistosomiasis often overlap in tropical and subtropical countries and impose tremendous disease burdens; however, the extent to which schistosomiasis modifies the risk of febrile malaria remains unclear.Methods
We evaluated the effect of baseline S. haematobium mono-infection, baseline P. falciparum mono-infection, and co-infection with both parasites on the risk of febrile malaria in a prospective cohort study of 616 children and adults living in Kalifabougou, Mali. Individuals with S. haematobium were treated with praziquantel within 6 weeks of enrollment. Malaria episodes were detected by weekly physical examination and self-referral for 7 months. The primary outcome was time to first or only malaria episode defined as fever (≥37.5°C) and parasitemia (≥2500 asexual parasites/µl). Secondary definitions of malaria using different parasite densities were also explored.Results
After adjusting for age, anemia status, sickle cell trait, distance from home to river, residence within a cluster of high S. haematobium transmission, and housing type, baseline P. falciparum mono-infection (n = 254) and co-infection (n = 39) were significantly associated with protection from febrile malaria by Cox regression (hazard ratios 0.71 and 0.44; P = 0.01 and 0.02; reference group: uninfected at baseline). Baseline S. haematobium mono-infection (n = 23) did not associate with malaria protection in the adjusted analysis, but this may be due to lack of statistical power. Anemia significantly interacted with co-infection (P = 0.009), and the malaria-protective effect of co-infection was strongest in non-anemic individuals. Co-infection was an independent negative predictor of lower parasite density at the first febrile malaria episode.Conclusions
Co-infection with S. haematobium and P. falciparum is significantly associated with reduced risk of febrile malaria in long-term asymptomatic carriers of P. falciparum. Future studies are needed to determine whether co-infection induces immunomodulatory mechanisms that protect against febrile malaria or whether genetic, behavioral, or environmental factors not accounted for here explain these findings. 相似文献3.
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Mahamadou S. Sissoko Abdoulaye Dabo Hamidou Traoré Mouctar Diallo Boubacar Traoré Drissa Konaté Boubacar Niaré Moussa Diakité Bourama Kamaté Abdrahamane Traoré Aboudramane Bathily Amadou Tapily Ousmane B. Touré Sarah Cauwenbergh Herwig F. Jansen Ogobara K. Doumbo 《PloS one》2009,4(10)
Background
This study was conducted to determine the efficacy of the antimalarial artemisinin-based combination therapy (ACT) artesunate +sulfamethoxypyrazine/pyrimethamine (As+SMP), administered in doses used for malaria, to treat Schistosoma haematobium in school aged children.Methodology/Principal Findings
The study was conducted in Djalakorodji, a peri-urban area of Bamako, Mali, using a double blind setup in which As+SMP was compared with praziquantel (PZQ). Urine samples were examined for Schistosoma haematobium on days −1, 0, 28 and 29. Detection of haematuria, and haematological and biochemical exams were conducted on day 0 and day 28. Clinical exams were performed on days 0, 1, 2, and 28. A total of 800 children were included in the trial. The cure rate obtained without viability testing was 43.9% in the As+SMP group versus 53% in the PZQ group (Chi2 = 6.44, p = 0.011). Egg reduction rates were 95.6% with PZQ in comparison with 92.8% with As+SMP, p = 0.096. The proportion of participants who experienced adverse events related to the medication was 0.5% (2/400) in As+SMP treated children compared to 2.3% (9/399) in the PZQ group (p = 0.033). Abdominal pain and vomiting were the most frequent adverse events in both treatment arms. All adverse events were categorized as mild.Conclusions/Significance
The study demonstrates that PZQ was more effective than As+SMP for treating Schistosoma haematobium. However, the safety and tolerability profile of As+SMP was similar to that seen with PZQ. Our findings suggest that further investigations seem justifiable to determine the dose/efficacy/safety pattern of As+SMP in the treatment of Schistosoma infections.Trial Registration
ClinicalTrials.gov NCT00510159http://clinicaltrials.gov/ct2/show/NCT00510159 相似文献
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