An analysis of the influence of the local effects of climatic and hydrological factors affecting new malaria cases in riverine areas along the Rio Negro and surrounding Puraquequara Lake, Amazonas, Brazil.

A study was conducted at three sampling regions along the Rio Negro and surrounding Puraquequara Lake, Amazonas, Brazil. The aim was to determine the influence of the local effects of climatic and hydrological variables on new malaria cases. Data was gathered on the river level, precipitation, air temperature, and the number of new cases of autochthonous malaria between January 2003 and December 2013. Monthly averages, time series decompositions, cross-correlations, and multiple regressions revealed different relationships at each location. The sampling region in the upper Rio Negro indicated no statistically significant results. However, monthly averages suggest that precipitation and air temperature correlate positively with the occurrence of new cases of malaria. In the mid Rio Negro and Puraquequara Lake, the river level positively correlated, and temperature negatively correlated with new transmissions, while precipitation correlated negatively in the mid Rio Negro and positively on the lake. Overall, the river level is a key variable affecting the formation of breeding sites, while precipitation may either develop or damage them. A negative temperature correlation is associated with the occurrence of new annual post-peak cases of malaria, when the monthly average exceeds 28.5 °C. This suggests that several factors contribute to the occurrence of new malaria cases as higher temperatures are reached at the same time as precipitation and the river levels are lowest. Differences between signals and correlation lags indicate that local characteristics have an impact on how different variables influence the disease vector's life cycle, pathogens, and consequently, new cases of malaria.

Effects of Neuroactive Drugs in the Discharge Patterns of Microsternarchus (Hypopomidae: Gymnotiformes) Electric Organ.

Considering the conserved nature of synaptic physiology among vertebrates, we tested the effects of three psychotropics (diazepam, doxapram, and nicotine) on Microsternarchus cf. bilineatus, measuring 10 parameters associated to the electric organ discharges rhythm and waveform before and after the administration of each drug and a control group. There were statistically significant differences (p < 0.005) among all the experimental groups, F (70, 22619.25) = 77.7, between the two experimental phases within their respective drug treatment, F (80, 24604.51) = 16.0, and among the six experimental hours within their respective phases and groups, F (320, 37124.15) = 4.1. We observed a common general trend of reduction in the electric organ's (EO) firing rate, regardless of the expected stimulant or depressor effect of the drugs on the central nervous system (CNS). The intensity of the response changed with the treatment. The observed changes in the fishes' behavior may be a result of the drugs' direct action on the CNS or a combination of this with systemic effects of each substance tested, also in the EO.