Eduardo Espinoza

Association of whale sharks (Rhincodon typus) with thermo-biological frontal systems of the eastern tropical Pacific

Satellite tracking of 27 whale sharks in the eastern tropical Pacific, examined in relation to environmental data, indicates preferential occupancy of thermo-biological frontal systems. In these systems, thermal gradients are caused by wind-forced circulation and mixing, and biological gradients are caused by associated nutrient enrichment and enhanced primary productivity. Two of the frontal systems result from upwelling, driven by divergence in the current systems along the equator and the west coast of South America; the third results from wind jet dynamics off Central America. All whale sharks were tagged near Darwin Island, Galápagos, within the equatorial Pacific upwelling system. Occupancy of frontal habitat is pronounced in synoptic patterns of shark locations in relation to serpentine, temporally varying thermal fronts across a zonal expanse > 4000 km. 80% of shark positions in northern equatorial upwelling habitat and 100% of positions in eastern boundary upwelling habitat were located within the upwelling front. Analysis of equatorial shark locations relative to thermal gradients reveals occupancy of a transition point in environmental stability. Equatorial subsurface tag data show residence in shallow, warm (>22°C) water 94% of the time. Surface zonal current speeds for all equatorial tracking explain only 16% of the variance in shark zonal movement speeds, indicating that passive drifting is not a primary determinant of movement patterns. Movement from equatorial to eastern boundary frontal zones occurred during boreal winter, when equatorial upwelling weakens seasonally. Off Peru sharks tracked upwelling frontal positions within ~100–350 km from the coast. Off Central America, the largest tagged shark (12.8 m TL) occupied an oceanic front along the periphery of the Panama wind jet. Seasonal movement from waning equatorial upwelling to productive eastern boundary habitat is consistent with underlying trophic dynamics. Persistent shallow residence in thermo-biological frontal zones suggests the role of physical-biological interactions that concentrate food resources.

Spatiotemporal analysis of canine rabies in El Salvador: Violence and poverty as social factors of canine rabies

Background The incidence of canine rabies cases in El Salvador has decreased in the last decade since the establishment of intense control programs, such as massive vaccination campaigns implemented by the Ministry of Health. Socioeconomic crises in recent years have limited the access to certain areas across the country and have impacted surveillance and prevention campaigns, which places the country at risk for a resurgence of canine rabies.We aimedto describe the spatiotemporal patterns of canine rabies and its association with critical social factors in El Salvador from 2005 to 2014. Method We included 459 cases of canine rabies. Several socioeconomic, demographic, and surveillance variables were modeled using a Poisson regression to evaluate their associations with the incidence of canine rabies. Spatial scan statistics were adjusted or unadjusted with covariates and applied to identify statistically significant clusters of canine rabies. Finally, a canine rabies risk map was created. Results A positive association and higher risk of canine rabies were found for low poverty zones, where it is suspected that urban slums contribute to ongoing rabies transmission (RR = 7.74). Violence had a negative association with rabies (RR = 0.663), which is likely due to reporting bias. Significant clusters were identified in all five epidemiological regions, and the Eastern region had the highest risk (RR = 50.62). The influences of the selected variables in cluster detection were confirmed by the adjusted analysis. Higher-risk townships were distributed from the Western to the Eastern regions of the country. Conclusion Social factors are determinants of rabies in El Salvador and play a major role in national spatial patterns of the disease. There are high-risk areas for canine rabies across the country, and there were two persistent rabies foci during the study period. Examining the role of social factors can provide better insight into rabies in vulnerable countries, and socioeconomic factors can be key elements in developing better policies and interventions for rabies control.