Impact of climate change on temperature variations and extrinsic incubation period of malaria parasites in Chennai, India: implications for its disease transmission potential.

BACKGROUND: The global temperature has significantly risen in the past century. Studies have indicated that higher temperature intensifies malaria transmission in tropical and temperate countries. Temperature fluctuations will have a potential impact on parasite development in the vector Anopheles mosquito. METHODS: Year-long microclimate temperatures were recorded from a malaria-endemic area, Chennai, India, from September 2021 to August 2022. HOBO data loggers were placed in different vector resting sites including indoor and outdoor roof types. Downloaded temperatures were categorised by season, and the mean temperature was compared with data from the same study area recorded from November 2012 to October 2013. The extrinsic incubation period for Plasmodium falciparum and P. vivax was calculated from longitudinal temperatures recorded during both periods. Vector surveillance was also carried out in the area during the summer season. RESULTS: In general, temperature and daily temperature range (DTR) have increased significantly compared to the 2012-2013 data, especially the DTR of indoor asbestos structures, from 4.30 â„ƒ to 12.62 â„ƒ in 2021-2022, unlike the marginal increase observed in thatched and concrete structures. Likewise, the average DTR of outdoor asbestos structures increased from 5.02 â„ƒ (2012-2013) to 8.76 â„ƒ (2021-2022) although the increase was marginal in thatched structures and, surprisingly, showed no such changes in concrete structures. The key finding of the extrinsic incubation period (EIP) is that a decreasing trend was observed in 2021-2022 compared to 2012-2013, mainly in indoor asbestos structures from 7.01 to 6.35 days, which negatively correlated with the current observation of an increase in temperature. Vector surveillance undertaken in the summer season revealed the presence of Anopheles breeding in various habitats. Anopheles stephensi could be collected using CDC light traps along with other mosquito species. CONCLUSION: The microclimate temperature has increased significantly over the years, and mosquitoes are gradually adapting to this rising temperature. Temperature negatively correlates with the extrinsic incubation period of the parasite. As the temperature increases, the development of the parasite in An. stephensi will be faster because of a decrease in EIP, thus requiring relatively fewer days, posing a risk for disease transmission and a hindrance to malaria elimination efforts.

Potential role of ambient temperature as a trigger for intracerebral hemorrhage: a time-stratified case-crossover study in Tianjin, China.

The adverse effects of ambient temperature on human health are receiving increasing attention, yet evidence of its impact on intracerebral hemorrhage (ICH) onset is limited. Here, the relationship between ambient temperature and ICH was evaluated. A time-stratified case-crossover analysis was performed based on 4051 ICH patients admitted to five stroke units in Tianjin between January 2014 and December 2020. Conditional logistic regression was applied to evaluate the associations between the daily mean temperature (Tm) or daily temperature range (DTR) and ICH onset. We found a negative association between Tm and ICH onset (OR = 0.977, 95% CI 0.968-0.987) but not between DTR and ICH onset. In stratified analyses, men and individuals aged ≥ 60 years were more susceptible to low-ambient temperature effects; corresponding adjusted ORs were 0.970 (95% CI 0.956-0.983) and 0.969 (95% CI 0.957-0.982), respectively. Tm significantly affected patients with deep ICH (OR = 0.976, 95% CI 0.965-0.988), but had no effect on lobar ICH. There was also seasonal heterogeneity in the effect of Tm on ICH onset, with Tm being negatively associated with ICH onset only in the warm season (OR = 0.961, 95% CI 0.941-0.982). Results suggest that the low-ambient temperature might trigger ICH onset, especially for the male and elderly population, providing important health guidance to prevent cold exposure-induced ICH.

High-sensitive solar terms in the onset of cerebral infarction and influence of temperature change / 中风与神经疾病杂志

@#Objective　To explore the high-sensitive solar terms and dominant meteorological factors in the onset of cerebral infarction,and to analyze the influence of daily temperature range and 24-hour temperature change on hospital admissions for cerebral infarction.Methods　Patients with cerebral infarction who were hospitalized in the First Teaching Hospital of Tianjin University of Traditional Chinese Medicine and the Second Hospital of Tianjin Medical University from January 2019 to December 2020 were retrospectively collected.The patients were grouped according to the twenty-four solar terms to explore the high-sensitive solar terms for the admission of cerebral infarction.A generalized linear Poisson regression model was established to explore the relationship between temperature changes and cerebral infarction admissions.Results　This study finally included 17 518 patients with cerebral infarction.There were statistically significant differences in the daily temperature range among different solar terms (P<0.001).The larger stages of the daily temperature range were from “Awakening of Insects” to “Grain in Ear”,and from “Autumn Equinox” to “Beginning of Winter”.The high-sensitive solar term of cerebral infarction admission was“Cold Dew”,which was located in the period of large daily temperature range.Daily temperature range was associated with cerebral infarction admission after multivariate adjustment (RR=1.01,95%CI 1.00~1.02,P=0.017),and had a hysteresis effect.With the increase of daily temperature range,the risk of cerebral infarction admissions increased,especially in males.Conclusion　“Cold Dew” is the high-sensitive solar term for cerebral infarction admission,and daily temperature range may be the dominant meteorological factor.The admission of cerebral infarction is related to the daily temperature range.

The Effect of Fluctuating Incubation Temperatures on West Nile Virus Infection in Culex Mosquitoes.

Temperature plays a significant role in the vector competence, extrinsic incubation period, and intensity of infection of arboviruses within mosquito vectors. Most laboratory infection studies use static incubation temperatures that may not accurately reflect daily temperature ranges (DTR) to which mosquitoes are exposed. This could potentially compromise the application of results to real world scenarios. We evaluated the effect of fluctuating DTR versus static temperature treatments on the infection, dissemination, and transmission rates and viral titers of Culex tarsalis and Culex quinquefasciatus mosquitoes for West Nile virus. Two DTR regimens were tested including an 11 and 15 °C range, both fluctuating around an average temperature of 28 °C. Overall, no significant differences were found between DTR and static treatments for infection, dissemination, or transmission rates for either species. However, significant treatment differences were identified for both Cx. tarsalis and Cx. quinquefasciatus viral titers. These effects were species-specific and most prominent later in the infection. These results indicate that future studies on WNV infections in Culex mosquitoes should consider employing realistic DTRs to reflect interactions most accurately between the virus, vector, and environment.

Improving Restoration Efficiency by Modeling Optimal Sowing Periods: A Case Study of Two Native Plants and Restoration of a Site.

Efficient ecological restoration techniques are urgently required to minimize seed consumption and labor requirements. Here, we determined the optimal sowing period for two native species, Agastache rugosa (Korean mint) and Astilbe rubra (False goat's beard), toward their use for ecological restoration of Mt. Gariwang, a site damaged by the 2018 PyeongChang Winter Olympics' activities. We investigated the effects of daily mean temperature (DMT) and daily temperature range (DTR) on seed germination percentage, which decreased for both species with decreasing DTR and was optimal at a DMT of 25 °C and 17.5 °C for A. rugosa and A. rubra, respectively. We developed a single multiple regression equation that evaluated the effects of DMT and DTR simultaneously and determined the temperature scores when the germination percentage reached 85%. We applied the developed multiple regression equation by analyzing the temperature data of the restoration site. In addition, precipitation data analysis was added to set the optimal sowing period. As a result, the optimal sowing period for the two species was determined from May 21 to the end of May. This makes it possible to minimize seed consumption and labor requirements when sowing seeds. The model developed herein will be useful not only to guide the ecological restoration of Mt. Gariwang, but also for other regions using site-specific temperature data.

Scaled outdoor experimental studies of urban thermal environment in street canyon models with various aspect ratios and thermal storage.

Street aspect ratios and urban thermal storage largely determine the thermal environment in cities. By performing scaled outdoor measurements in summer of 2017 in Guangzhou, China, we investigate these impacts on spatial/temporal characteristics of urban thermal environment which are still unclear so far. Two types of street canyon models are investigated, i.e. the 'hollow' model resembling hollow concrete buildings and the 'sand' model consisting of buildings filled with sand attaining much greater thermal storage. For each model, three street aspect ratios (building height/street width, H/W = 1, 2, 3; H = 1.2 m) are considered. The diurnal variations of air-wall surface temperatures are observed and their characteristics are quantified for various cases. The daily average temperature and daily temperature range (DTR) of wall temperature vary significantly with different aspect ratios and thermal storage. During the daytime, wider street canyon (H/W = 1) with less shading area experiences higher temperature than narrower ones (H/W = 2, 3) as more solar radiation received by wall surfaces. At night, wider street canyon cools down quicker due to stronger upward longwave radiation and night ventilation. For hollow models, H/W = 1 attains DTR of 12.1 °C, which is 1.2 and 2.1 °C larger than that of H/W = 2, 3. Moreover, the sand models experience smaller DTR and a less changing rate of wall temperature than hollow models because larger thermal storage absorbs more heat in the daytime and releases more at night. DTR of hollow models with H/W = 1, 2, 3 is 4.5, 4.6 and 3.8 °C greater than sand models respectively. For both hollow and sand models, wider streets experience a little higher daily average temperature (0.3-0.6 °C) than narrower ones. Our study provides direct evidence in how man-made urban structures influence urban climate and also suggests the possibility to control outdoor thermal environment by optimize urban morphology and thermal storage.

Associations between Ambient Temperature and Acute Myocardial Infarction.

BACKGROUND: The associations between incidence of acute myocardial infarction (AMI) and the ambient temperature were mixed in prior studies. METHODS: Data of 2033 consecutive admissions of AMI in a central tertiary hospital in North China from 1st Jan 2003 to 31st Dec 2011 were collected. The weather data in this period were from the local meteorological department. Based on the ambient temperature information, we defined several ambient temperature indices, including daily average temperature, extremely low temperature, and daily temperature range, then characterized the independent associations between them and the incidence of AMI. RESULTS: The daily average temperature one day before was independently associated with AMI incidence rate: a rise of 5°C of the daily average temperature led to a 5% decrease in AMI admissions. Daily average temperature and temperature range two days before were independently associated with AMI incidence rate: a rise of 5°C of the daily average temperature led to a fall of 6% in AMI admissions, and a rise of 2°C of the daily temperature range led to a rise of 4% in AMI admission. CONCLUSION: Low ambient temperature has substantial association with AMI, and can play an important role in warning and forecasting the incidence.

Microclimate variables of the ambient environment deliver the actual estimates of the extrinsic incubation period of Plasmodium vivax and Plasmodium falciparum: a study from a malaria-endemic urban setting, Chennai in India.

BACKGROUND: Environmental factors such as temperature, relative humidity and their daily variation influence a range of mosquito life history traits and hence, malaria transmission. The standard way of characterizing environmental factors with meteorological station data need not be the actual microclimates experienced by mosquitoes within local transmission settings. METHODS: A year-long study was conducted in Chennai, India to characterize local temperature and relative humidity (RH). Data loggers (Hobos) were placed in a range of probable indoor and outdoor resting sites of Anopheles stephensi. Recordings were taken hourly to estimate mean temperature and RH, together with daily temperature range (DTR) and daily relative humidity range. The temperature data were used to explore the predicted variation in extrinsic incubation period (EIP) of Plasmodium falciparum and Plasmodium vivax between microhabitats and across the year. RESULTS: Mean daily temperatures within the indoor settings were significantly warmer than those recorded outdoors. DTR in indoor environments was observed to be modest and ranged from 2 to 6 °C. Differences in EIP between microhabitats were most notable during the hottest summer months of April-June, with parasite development predicted to be impaired for tiled houses and overhead tanks. Overall, the prevailing warm and stable conditions suggest rapid parasite development rate regardless of where mosquitoes might rest. Taking account of seasonal and local environmental variation, the predicted EIP of P. falciparum varied from a minimum of 9.1 days to a maximum of 15.3 days, while the EIP of P. vivax varied from 8.0 to 24.3 days. CONCLUSIONS: This study provides a detailed picture of the actual microclimates experienced by mosquitoes in an urban slum malaria setting. The data indicate differences between microhabitats that could impact mosquito and parasite life history traits. The predicted effects for EIP are often relatively subtle, but variation between minimum and maximum EIPs can play a role in disease transmission, depending on the time of year and where mosquitoes rest. Appropriate characterization of the local microclimate conditions would be the key to fully understand the effects of environment on local transmission ecology.

Effect of daily temperature range on respiratory health in Argentina and its modification by impaired socio-economic conditions and PM10 exposures.

Epidemiological investigations regarding temperature influence on human health have focused on mortality rather than morbidity. In addition, most information comes from developed countries despite the increasing evidence that climate change will have devastating impacts on disadvantaged populations living in developing countries. In the present study, we assessed the impact of daily temperature range on upper and lower respiratory infections in Cordoba, Argentina, and explored the effect modification of socio-economic factors and influence of airborne particles We found that temperature range is a strong risk factor for admissions due to both upper and lower respiratory infections, particularly in elderly individuals, and that these effects are more pronounced in sub-populations with low education level or in poor living conditions. These results indicate that socio-economic factors are strong modifiers of the association between temperature variability and respiratory morbidity, thus they should be considered in risk assessments.

Fine-scale temperature fluctuation and modulation of Dirofilaria immitis larval development in Aedes aegypti.

We evaluated degree-day predictions of Dirofilaria immitis development (HDU) under constant and fluctuating temperature treatments of equal average daily temperature. Aedes aegypti mosquitoes were infected with D. immitis microfilariae and parasite development was recorded at set time points in dissected mosquitoes. Time to L3 development in Malpighian tubules and detection in mosquito heads was shorter for larvae experiencing a daily regime of 19±9°C than larvae at constant 19°C; larval development rate in Malpighian tubules was slower in fluctuating regimes maintained above the 14°C developmental threshold than larvae under constant temperatures. We showed that hourly temperature modeling more accurately predicted D. immitis development to infective L3 stage. Development time differed between fluctuating and constant temperature treatments spanning the 14°C development threshold, implicating a physiological basis for these discrepancies. We conclude that average daily temperature models underestimate L3 development-and consequently dog heartworm transmission risk-at colder temperatures, and spatiotemporal models of D. immitis transmission risk should use hourly temperature data when analyzing high daily temperature ranges spanning 14°C.