Projections of excess mortality related to diurnal temperature range under climate change scenarios: a multi-country modelling study

Background. Various retrospective studies have reported on the increase of mortality risk due to higher diurnal temperature range (DTR). This study projects the effect of DTR on future mortality across 445 communities in 20 countries and regions. Methods. DTR-related mortality risk was estimated on the basis of the historical daily time-series of mortality and weather factors from Jan 1, 1985, to Dec 31, 2015, with data for 445 communities across 20 countries and regions, from the Multi-Country Multi-City Collaborative Research Network. We obtained daily projected temperature series associated with four climate change scenarios, using the four representative concentration pathways (RCPs) described by the Intergovernmental Panel on Climate Change, from the lowest to the highest emission scenarios (RCP 2.6, RCP 4.5, RCP 6.0, and RCP 8.5). Excess deaths attributable to the DTR during the current (1985–2015) and future (2020–99) periods were projected using daily DTR series under the four scenarios. Future excess deaths were calculated on the basis of assumptions that warmer long-term average temperatures affect or do not affect the DTR-related mortality risk. Findings. The time-series analyses results showed that DTR was associated with excess mortality. Under the unmitigated climate change scenario (RCP 8.5), the future average DTR is projected to increase in most countries and regions (by −0·4 to 1·6°C), particularly in the USA, south-central Europe, Mexico, and South Africa. The excess deaths currently attributable to DTR were estimated to be 0·2–7·4%. Furthermore, the DTR-related mortality risk increased as the long-term average temperature increased; in the linear mixed model with the assumption of an interactive effect with long-term average temperature, we estimated 0·05% additional DTR mortality risk per 1°C increase in average temperature. Based on the interaction with long-term average temperature, the DTR-related excess deaths are projected to increase in all countries or regions by 1·4–10·3% in 2090–99. Interpretation. This study suggests that globally, DTR-related excess mortality might increase under climate change, and this increasing pattern is likely to vary between countries and regions. Considering climatic changes, our findings could contribute to public health interventions aimed at reducing the impact of DTR on human health.We thank the Korea Ministry of Environment for funding this study through the Climate Change Correspondence Programme (2014001310007); HK is supported by this programme. NS was supported by the HERCULES Center (P30ES019776), funded by the US National Institute of Environmental Health Science. JM was supported by the Fundação para a Ciência e a Tecnologia through a scholarship (SFRH/ BPD/115112/2016). AG was supported by the UK Medical Research Council (MR/M022625/1), the UK Natural Environment Research Council (NE/R009384/1), and the EU Horizon 2020 project, Exhaustion (820655)

Parasitological characteristics and tissue response in the abomasum of sheep infected with Haemonchus spp. Características parasitológicas e resposta tissular do abomaso em cordeiros infectados por Haemonchus spp.

A histopathological study was conducted on the abomasal mucosa of 40 Corriedale sheep exposed to natural infection with Haemonchus spp. The sheep were allowed to graze on contaminated pastures for 14 days and, after being housed for 28 days, they were slaughtered. Fecal samples were collected for fecal egg counts (FEC) and abomasum samples were obtained for histopathological examination and eosinophil, mast cell and globule leucocyte counts. The number of Haemonchus spp. present in the abomasum was estimated from a 10% aliquot of its content. The number of eggs per female was estimated for 10 Haemonchus spp. females collected from each animal. The following significant correlation coefficients were obtained between the characteristics analyzed: number of Haemonchus and FEC (r = 0.86), female length and number of eggs per female (r = 0.60), female length and FEC (r = 0.53), number of eosinophils and number of Haemonchus (r = 0.48), number of eosinophils and number of globule leucocytes (r = 0.54), number of mast cells and female length (r = -0.39), and number of mast cells and number of globule leucocyte (r = 0.34). The characteristics that showed the highest correlation with animal load was FEC.<br>Realizou-se um estudo histopatológico da mucosa do abomaso de 40 cordeiros da raça Corriedale, expostos à infecção natural por Haemonchus spp. Os cordeiros foram colocados em pastagens contaminadas por 14 dias e após 28 dias de estabulação foram necropsiados. Por ocasião da necropsia, foram colhidas amostras de fezes para a realização da contagem de ovos por grama de fezes (OPG) e amostras do abomaso para exame histopatológico e contagem do número de eosinófilos, mastócitos e leucócitos globulares. O número de Haemonchus spp. presente no abomaso foi estimado a partir de uma alíquota de 10% do conteúdo. O número de ovos por fêmea foi estimado em 10 fêmeas de Haemonchus spp. colhidas de cada animal. Coeficientes de correlação significativos entre as características analisadas foram: número de Haemonchus e contagem de OPG (r = 0,86); comprimento de fêmeas e número de ovos por fêmea (r = 0,60); comprimento de fêmeas e contagem de OPG (r = 0,53); número de eosinófilos e número de Haemonchus (r = 0,48); número de eosinófilos e número de leucócitos globulares (r = 0,54); número de mastócitos e comprimento de fêmeas (r = -0,39) e número de mastócitos e número de leucócitos globulares (r = 0,34). Das características analisadas a que apresentou maior correlação com a carga parasitária dos animais foi a contagem de OPG