摘要
Objective:To determine the ecological parameters affecting the distribution of Simulium damnosum immature stages in some rivers within the endemic areas of Delta State,Nigeria.Methods:Onchocerca larvae were observed and identified for each river.An average sized colander with fine mesh was used to scoop the area to obtain the larvae along with other benthos.Physiochemical characteristics of the water at breeding sites were analyzed for a 12 months period.Correlation analysis was performed to establish the association between the larval densities and physicochemical parameters of blackfly.Results:The seasonal variation in the physical and chemical characteristics of these environments impaired the population dynamics of blackflies.The physicochemical parameters significantly varied among breeding sites(P<0.05),in which the temperature of surface water ranged between 23.2°C and 30.3°C,water flow velocity ranged between 0.4 and 1.3 m/s,dissolved oxygen ranged between 5.1 and 9.0 mg/L and pH ranged between 5.4 and 7.4.The mean collection of Simulium larvae was the highest in River Otor(44.1)and the least in River Namormai(19.1).There was significant difference(P<0.05)in the number of larvae collected from the sampled rivers.Also,the number of larvae collected significantly correlated with surface water temperature,water flow velocity,dissolved oxygen and pH.Conclusions:This study identified significant correlations between physicochemical parameters and blackfly larvae densities thus providing a precontrol evidence-based data for the control of onchocerciasis in the endemic areas of North Delta.
基金
Special thanks to the Delta State Ministry of Health for granting the ethical permit for the study.The cooperation of the community heads is well acknowledged
