Mortality related to cold and heat. What do we learn from dairy cattle?

Impacts of heatwaves on type 2 diabetes mortality in China: a comparative analysis between coastal and inland cities

The impacts of extreme temperatures on diabetes have been explored in previous studies. However, it is unknown whether the impacts of heatwaves appear variations between inland and coastal regions. This study aims to quantify the associations between heat exposure and type 2 diabetes mellitus (T2DM) deaths in two cities with different climate features in Shandong Province, China. We used a case-crossover design by quasi-Poisson generalized additive regression with a distributed lag model with lag 2 weeks, controlling for relative humidity, the concentration of air pollution particles with a diameter of 2.5 µm or less (PM2.5), and seasonality. The wet- bulb temperature (Tw) was used to measure the heat stress of the heatwaves. A significant association between heatwaves and T2DM deaths was only found in the coastal city (Qingdao) at the lag of 2 weeks at the lowest Tw = 14℃ (relative risk (RR) = 1.49, 95% confidence interval (CI): 1.11-2.02; women: RR = 1.51, 95% CI: 1.02-2.24; elderly: RR = 1.50, 95% CI: 1.08-2.09). The lag-specific effects were significant associated with Tw at lag of 1 week at the lowest Tw = 14℃ (RR = 1.14, 95% CI: 1.03-1.26; women: RR = 1.15, 95% CI: 1.01-1.31; elderly: RR = 1.15, 95% CI: 1.03-1.28). However, no significant association was found in Jian city. The research suggested that Tw was significantly associated with T2DM mortality in the coastal city during heatwaves on T2DM mortality. Future strategies should be implemented with considering socio-environmental contexts in regions.

How multiple air pollutants affect hand, foot, and mouth disease incidence in children: assessing effect modification by geographical context in multicity of Sichuan, southwest China

BACKGROUND

Several studies have suggested a significant association of hand, foot, and mouth disease (HFMD) with ambient air pollutants. Existing studies have characterized the role of air pollutants on HFMD using only risk ratio measures while ignoring the attributable burden. And whether the geographical context (i.e., diverse topographic features) could modulate the relationships is unclear.

METHODS

Daily reported childhood HFMD counts, ambient air pollution, and meteorological data during 2015-2017 were collected for each of 21 cities in Sichuan Province. A multistage analysis was carried out in different populations based on geographical context to assess effect modification by topographic conditions. We first constructed a distributed lag nonlinear model (DLNM) for each city to describe the relationships with risk ratio measures. Then, we applied a multivariate meta-regression to estimate the pooled effects of multiple air pollutants on HFMD from the exposure and lagged dimensions. Finally, attributable risks measures were calculated to quantify HFMD burden by air pollution.

RESULTS

Based on 207554 HFMD cases in Sichuan Province, significant associations of HFMD with ambient air pollutants were observed mainly at relatively high exposure ranges. The effects of ambient air pollutants on HFMD are most pronounced on lag0 or around lag7, with relative risks gradually approaching the reference line thereafter. The attributable risks of O3 were much greater than those of other air pollutants, particularly in basin and mountain regions.

CONCLUSIONS

This study revealed significant pooled relationships between multiple air pollutants and HFMD incidence from both exposure and lag dimensions. However, the specific effects, including RRs and ARs, differ depending on the air pollution variable and geographical context. These findings provide local authorities with more evidence to determine key air pollutants and regions for devising and implementing targeted interventions.

A systematic review of the effects of silvopastoral system on thermal environment and dairy cows' behavioral and physiological responses

Does the silvopastoral system (SPS) promote a satisfactory thermal environment for dairy cows to perform their natural behaviors and perform a suitable thermoregulatory function? To answer this, peer-reviewed articles, written in English and evaluating the effects of silvopastoral systems on thermal environment, dairy cows' behavior, and physiology were used in this systematic review; additionally, a bibliometric approach was performed. Web of Science and Google Scholar were used to compile the literature. The resulting articles (1448) underwent a 4-step appraisal process and resulted in 19 articles that fitted our inclusion criteria. Microclimate variables and thermal comfort indicators were the most researched topics (discussed in 89% of studies); 47% of studies addressed cattle behavior and 36% physiological responses. Our review highlights different benefits of silvopastoral systems for grazing dairy cows. For example, the SPS provides a more comfortable thermal environment than treeless pasture, which increases feeding behaviors; furthermore, dairy cows in SPS show lower drinking events, surface temperature, and respiratory rate than cows raised in treeless pasture. However, for nine of the variables related to cows' behavior (e.g., resting, rumination) and physiology responses (e.g., internal temperature), the results of the studies were unclear. Furthermore, behaviors associated with lying down (e.g., idling and rumination) and milk production in SPS were explored only in six and two studies, respectively. These findings provide consistent evidence that the silvopastoral systems are beneficial to thermal comfort of dairy cows; nonetheless, the effect on cows' behavioral and physiological responses is still scarce and unclear.

High temperatures and human pressures interact to influence mortality in an African carnivore

The impacts of high ambient temperatures on mortality in humans and domestic animals are well-understood. However much less is known about how hot weather affects mortality in wild animals. High ambient temperatures have been associated with African wild dog Lycaon pictus pup mortality, suggesting that high temperatures might also be linked to high adult mortality.We analyzed mortality patterns in African wild dogs radio-collared in Kenya (0°N), Botswana (20°S), and Zimbabwe (20°S), to examine whether ambient temperature was associated with adult mortality.We found that high ambient temperatures were associated with increased adult wild dog mortality at the Kenya site, and there was some evidence for temperature associations with mortality at the Botswana and Zimbabwe sites.At the Kenya study site, which had the highest human impact, high ambient temperatures were associated with increased risks of wild dogs being killed by people, and by domestic dog diseases. In contrast, temperature was not associated with the risk of snare-related mortality at the Zimbabwe site, which had the second-highest human impact. Causes of death varied markedly between sites.Pack size was positively associated with survival at all three sites.These findings suggest that while climate change may not lead to new causes of mortality, rising temperatures may exacerbate existing anthropogenic threats to this endangered species, with implications for conservation. This evidence suggests that temperature-related mortality, including interactions between temperature and other anthropogenic threats, should be investigated in a greater number of species to understand and mitigate likely impacts of climate change. ​.

Evaluating the association between climatic factors and sheep condemnations in the United States using cluster analysis and spatio-temporal modeling

Sheep in the United States are primarily raised and fed on pasture, making them particularly susceptible to the impacts of climatic factors. This study sought to evaluate the association between climate and whole carcass condemnations in the U.S. as a proxy to evaluate overall sheep health across the U.S. USDA FSIS inspection data was evaluated for whole carcass sheep condemnations between 2005-2016. The analysis focused on condemnations attributed to caseous lymphadenitis, the most frequent cause of sheep condemnations during this period. Data was analyzed on the climate division scale - 344 subdivisions of the contiguous United States that divide states into nearly homogenous climatic regions. Using space-time cluster analysis for high rates of condemnations, ten clusters were identified ranging across the United States. All but one of these clusters was confined to single climate division, with lengths ranging from 1 to 72 months. A zero-inflated Poisson regression found significant associations between condemnation counts and precipitation, cooling degree days (an indicator of higher temperatures), year, and division of the United States. The model had a marginal R-squared of 0.54. This study has identified high risk clusters where higher than expected condemnations are concentrated. The confirmation of an association between climatic factors and condemnation numbers suggests that management practices targeted at protecting pasture-raised small ruminants from weather extremes would improve overall animal health and welfare. Mitigation strategies should be considered as we face increasing frequency of extreme weather events and other environmental fluctuations associated with climate change.

A systematic review on lagged associations in climate-health studies

BACKGROUND

Lagged associations in climate-health studies have already been ubiquitously acknowledged in recent years. Despite extensive time-series models having proposed accounting for lags, few studies have addressed the question of maximum-lag specification, which could induce considerable deviations of effect estimates.

METHODS

We searched the PubMed and Scopus electronic databases for existing climate-health literature in the English language with a time-series or case-crossover study design published during 2000-2019 to summarize the statistical methodologies and reported lags of associations between climate variables and 14 common causes of morbidity and mortality. We also aggregated the results of the included studies by country and climate zone.

RESULTS

The associations between infectious-disease outcomes and temperatures were found to be lagged for ∼1-2 weeks for influenza, 3-6 weeks for diarrhoea, 7-12 weeks for malaria and 6-16 weeks for dengue fever. Meanwhile, the associations between both cardiovascular and respiratory diseases and hot temperatures lasted for <5 days, whereas the associations between cardiovascular diseases and cold temperatures were observed to be 10-20 days. In addition, rainfall showed a 4- to 10-week lagged association with infectious diarrheal diseases, whereas the association could be further delayed to 8-12 weeks for vector-borne diseases.

CONCLUSION

Our findings indicated some general patterns for possible lagged associations between some common health outcomes and climatic exposures, and suggested a necessity for a biologically plausible and reasonable definition of the effect lag in the modelling practices for future environmental epidemiological studies.

The burden of childhood hand-foot-mouth disease morbidity attributable to relative humidity: a multicity study in the Sichuan Basin, China

Hand, foot and mouth disease (HFMD) is a growing threat to children's health, causing a serious public health burden in China. The relationships between associated meteorological factors and HFMD have been widely studied. However, the HFMD burden due to relative humidity from the perspective of attributable risk has been neglected. This study investigated the humidity-HFMD relationship in three comprehensive perspectives, humidity-HFMD relationship curves, effect modification and attributable risks in the Sichuan Basin between 2011 and 2017. We used multistage analyses composed of distributed lag nonlinear models (DLNMs), a multivariate meta-regression model and the calculations of attributable risk to quantify the humidity-HFMD association. We observed a J-shaped pattern for the pooled cumulative humidity-HFMD relationship, which presented significant heterogeneity relating to the geographical region and number of primary school students. Overall, 27.77% (95% CI 25.24–30.02%) of HFMD infections were attributed to humidity. High relative humidity resulted in the greatest burden of HFMD infections. The proportion of high humidity-related HFMD in the southern basin was higher than that in the northern basin. The findings provide evidence from multiple perspectives for public health policy formulation and health resource allocation to develop priorities and targeted policies to ease the HFMD burden associated with humidity.

Impact of climate change on sustainable livestock production and existence of wildlife and marine species in the South Pacific island countries: a review

Climate change poses a significant threat to humanity by intensifying multiple hazards. South Pacific Island countries (SPICs) are affected and face a dire challenge to survival. Sea level rise is reducing the already limited land for human and animal habitation. Tropical cyclones and droughts are having devastating effects on the lives of humans and animals. Tropical cyclone Winston, for example, destroyed infrastructure for humans and animals in some parts of Fiji, and infectious diseases are spreading to regions where they are not commonly seen following cyclones and floods. Likewise, climate change is making droughts worse. Droughts are destroying crops and pasturelands and making freshwater unavailable for human and animal populations in the Solomon Islands and Tuvalu. There is an urgent need to ascertain the best approaches to tackle the events, which are already happening. Short-term changes can be managed at local levels through public awareness campaigns, understanding the weather patterns to prepare for disasters, reclaiming land, improving livestock breeds, introducing zoos and wildlife sanctuaries and inventing economically feasible technologies to harvest water. Long-term solutions depend on the implementation of international agreements, international aid and collective effort.

Influence of temperature on prevalence of health and welfare conditions in pigs: time-series analysis of pig abattoir inspection data in England and Wales

The prevalence of many diseases in pigs displays seasonal distributions. Despite growing concerns about the impacts of climate change, we do not yet have a good understanding of the role that weather factors play in explaining such seasonal patterns. In this study, national and county-level aggregated abattoir inspection data were assessed for England and Wales during 2010–2015. Seasonally-adjusted relationships were characterised between weekly ambient maximum temperature and the prevalence of both respiratory conditions and tail biting detected at slaughter. The prevalence of respiratory conditions showed cyclical annual patterns with peaks in the summer months and troughs in the winter months each year. However, there were no obvious associations with either high or low temperatures. The prevalence of tail biting generally increased as temperatures decreased, but associations were not supported by statistical evidence: across all counties there was a relative risk of 1.028 (95% CI 0.776–1.363) for every 1 °C fall in temperature. Whilst the seasonal patterns observed in this study are similar to those reported in previous studies, the lack of statistical evidence for an explicit association with ambient temperature may possibly be explained by the lack of information on date of disease onset. There is also the possibility that other time-varying factors not investigated here may be driving some of the seasonal patterns.

The Association between Air Temperature and Mortality in Two Brazilian Health Regions

Air temperature, both cold and hot, has impacts on mortality and morbidities, which are exacerbated by poor health service and protection responses, particularly in under-developed countries. This study was designed to analyze the effects of air temperature on the risk of deaths for all and specific causes in two regions of Brazil (Florianopolis and Recife), between 2005 and 2014. The association between temperature and mortality was performed through the fitting of a quasi-Poisson non-linear lag distributed model. The association between air temperature and mortality was identified for both regions. The results showed that temperature exerted influence on both general mortality indicators and specific causes, with hot and cold temperatures bringing different impacts to the studied regions. Cerebrovascular and cardiovascular deaths were more sensitive to cold temperatures for Florianopolis and Recife, respectively. Based on the application of the very-well documented state-of-the-art methodology, it was possible to conclude that there was evidence that extreme air temperature influenced general and specific deaths. These results highlighted the importance of consolidating evidence and research in tropical countries such as Brazil as a way of understanding climate change and its impacts on health indicators.

Short-term effects of air pollution and temperature on cattle mortality in the Netherlands

BACKGROUND

Extreme temperatures and air pollution are both associated with increased mortality risk in humans. However, the effects of temperature and air pollution on cattle have not been investigated much before.

OBJECTIVES

Short-term effects of temperature (heat and cold) and air pollution on cattle mortality were investigated and quantified in the Netherlands during 2012-2017.

METHODS

Daily data on cattle mortality, weather conditions and mean levels of particulate matter (PM₁₀), ozone (O₃), ammonia (NH₃) and nitrogen dioxide (NO₂) of the Netherlands during 2012-2017 were collected. Associations were investigated with time-series regression using distributed lag non-linear models including lags of up to 25 days. Effects of temperature were expressed as those associated with extreme and moderate heat or cold, defined as Temperature Humidity Index (THI) values below the 1st and 5th percentile, and above the 95th and 99th percentile of the national THI distribution. Effects of air pollutants were expressed per 10 μg/m³ change in daily mean concentrations.

RESULTS

Both high and low temperatures were associated with increased mortality amongst different age groups. For instance, the newborn calves of at most 14 days showed a cumulative relative risk (RR) of 2.13 (95%CI: 1.99-2.28) for extreme heat and the pre-weaned calves (15-55 days) showed a cumulative RR of 1.50 (95%CI: 1.37-1.64) for extreme cold. Associations of air pollution with mortality were not consistent, except for the effect of ozone of lag 0-7 and lag 0-25. Exposure to O₃ in the newborn calves resulted in a cumulative RR of 1.09 (95%CI: 1.04-1.4) for lag 0-7 and 1.09 (95%CI: 1.03-1.16) for lag 0-25.

CONCLUSIONS

Both high and low temperatures were associated with increased mortality amongst pre-weaned calves of 15-55 days, whereas associations in weaned calves (56 days - 1 year) were only observed for low temperatures and in newborn calves of at most 14 days and lactating cattle >2 years only for high temperatures. Associations of air pollution with mortality in all age groups were not consistent, except for the effect of ozone of lag 0-7 and lag 0-25.

Association between human and animal thermal comfort indices and physiological heat stress indicators in dairy calves

Warm summer episodes have a significant effect on the overall health and well-being of young cattle; however, it is not known which temperature measure should be used for estimating heat stress in dairy calves. In this study, generalized linear mixed-effects models were used to estimate the relationships between thermal comfort indices and animal-based heat stress indicators in sixteen Holstein bull calves that were housed in individual calf hutches. Data were collected under continental weather characteristics over a 5-day period: day 1 (lower-temperature day), days 2 and 3 (heat stress days), and a 2-day post-stress period. Relative humidity, ambient temperature, the heat index, the humidex and five different temperature-humidity indices (THI) were used as thermal indices. Physiological variables monitored included respiratory rate, rectal temperature, ear skin temperature and heart rate. The heat index and the humidex measuring human thermal comfort were more closely associated with physiological measures than were the ambient temperature or the THIs (in case of heat index: R² = 0.87 for respiratory rate, R² = 0.63 for rectal temperature, R² = 0.70 for ear skin temperature, and R² = 0.78 for heart rate, respectively; in case of humidex: R² = 0.85 for respiratory rate, R² = 0.60 for rectal temperature, R² = 0.68 for ear skin temperature, and R² = 0.75 for heart rate, respectively). Based on our results, parameters of human outdoor comfort seem better to estimate heat stress in dairy calves in a continental region than those of THIs or ambient temperature.

Descriptive study for culling and mortality in five high-producing Spanish dairy cattle farms (2006-2016)

Background

High turnover rate in dairy farms due to culling and mortality is associated with poor animal welfare, an increase in production costs and lower economic benefits for the dairy farm. Understanding cow elimination better would help to formulate specific prevention measures and improve the efficiency of milk production in dairy farms. Culling and mortality data from five standard high-producing dairy farms in Spain were analysed over a period of 11 years (2006–2016). Data were collected by the same veterinary team and using the same software system.

Results

Significant between-herd differences in eliminated cows were observed for type of elimination (slaughter or death on the farm), age at elimination, cause of elimination, number of lactations and production parameters, such as total days in milk, life milk yield, litres per day of productive life and litres per day of life. Culling and mortality were higher during the hot season and for cows of second and third parities. Between-herd differences were observed. Reproductive disorders (30.2%) were the most frequent reason for elimination, with low production (23.4%) being the second most frequent reason. Accidents on the farm (7.7%) were a more frequent cause of elimination than metabolic diseases (7.2%), locomotor disorders (2.4%) and obstetrics (2.4%).

Conclusions

Veterinary teams or farmers’ associations can use culling and mortality information for benchmarking cow farms if data collection and analysis is standardised for comparability. The analysis of culling and mortality information should help farmers to improve efficiency.

Electronic supplementary material

The online version of this article (10.1186/s13028-018-0399-z) contains supplementary material, which is available to authorized users.

Heat/mortality sensitivities in Los Angeles during winter: a unique phenomenon in the United States

BACKGROUND

Extreme heat is often associated with elevated levels of human mortality, particularly across the mid-latitudes. Los Angeles, CA exhibits a unique, highly variable winter climate, with brief periods of intense heat caused by downsloping winds commonly known as Santa Ana winds. The goal is to determine if Los Angeles County is susceptible to heat-related mortality during the winter season. This is the first study to specifically evaluate heat-related mortality during the winter for a U.S. city.

METHODS

Utilizing the Spatial Synoptic Classification system in Los Angeles County from 1979 through 2010, we first relate daily human mortality to synoptic air mass type during the winter season (December, January, February) using Welch's t-tests. However, this methodology is only somewhat effective at controlling for important inter- and intra-annual trends in human mortality unrelated to heat such as influenza outbreaks. As a result, we use distributed lag nonlinear modeling (DLNM) to evaluate if the relative risk of human mortality increases during higher temperatures in Los Angeles, as the DLNM is more effective at controlling for variability at multiple temporal scales within the human mortality dataset.

RESULTS

Significantly higher human mortality is uncovered in winter when dry tropical air is present in Los Angeles, particularly among those 65 years and older (p < 0.001). The DLNM reveals the relative risk of human mortality increases when above average temperatures are present. Results are especially pronounced for maximum and mean temperatures, along with total mortality and those 65 + .

CONCLUSIONS

The discovery of heat-related mortality in winter is a unique finding in the United States, and we recommend stakeholders consider warning and intervention techniques to mitigate the role of winter heat on human health in the County.

Milk production and blood metabolites of dairy cattle as influenced by thermal-humidity index

The effects of high thermal stress on serum protein metabolites, milk production of transition dairy cows in semi-arid areas in South Africa were evaluated. Forty, ± 8 months pregnant, Jersey heifers (± 26 months) in zero grazing management were selected during summer from two semi-arid communal areas. Summer thermal-humidity index (THI) of the areas were THI-1 (72–83: extreme caution) and THI-2 (75–87: danger). Blood samples were collected (21 days pre-partum, and 21 and 75 days post-partum) and analysed for serum protein metabolites. Milk yield was recorded daily and samples collected for milk fat, protein, lactose and urea nitrogen analysis. Heifers in THI-2 had lower (P < 0.05) total serum proteins, albumin and blood urea nitrogen than THI-1. Post-calving, cows in THI-1 had higher (P < 0.05) TP (73.4 vs 67.9 g/l) and BUN (4.61 vs 3.77 mmol/l) at 21 DIM, and lower (P creatinine at 21 and 75 DIM than THI-2 group. Milk yield, fat and protein in THI-2 were all lower (P < 0.05) than THI-1 21DIM. The results confirm that heat stress affects utilisation of nutrients in transition dairy cows.