Effects of high temperatures on poor mental health outcomes: a systematic review and meta-analysis

Background

In the context of warming temperature and increased prevalence of mental disorders, a growing body of literature suggests the adverse effects of high temperatures on mental health. However, no study has quantitatively summarised the evidence. This study therefore systematically reviews the epidemiological evidence and summarises the quantitative effects of high temperatures on mental health outcomes, including mortality and morbidity.

Methods

A systematic search of peer-reviewed epidemiological studies in five databases that linked high temperatures and mental health was conducted on literature published till November 2020. A range of mental health conditions were defined using ICD-10 classifications. We included studies that examined the quantitative association between temperatures and mental health mortality or morbidity (i.e. hospital admissions, emergency presentations) in the general population. Random-effects models were used to summarise the percentage changes in mental health outcomes per 1 °C temperature increase.

Results

The keyword search yielded 4560 citations from which 34 studies were included in the meta-analysis. For 1 °C increase in temperature, the risk of mental health-related mortality and morbidity increased by 2.2% (95%CI: 1.5-2.9%) and 0.9% (95%CI: 0.7-1.5%). The greatest risk was associated with mortality attributed to substance-related mental disorders (4.6%; 95%CI: 0-10.1%), and organic mental disorders (3.3%; 95%CI: 2-4.6%). A 1 °C temperature rise was also associated with a statistically significant increase in morbidity such as mood disorders, organic mental disorders, and schizophrenia. Higher risk was evident for elderly and populations living in tropical and subtropical climate zones.

Conclusions

Our results suggest that exposure to high temperatures increases the risk of poor mental health outcomes. These risks will likely increase with a warming climate.

Key messages

High temperatures are associated with poor mental health outcomes, including mortality and morbidity. The findings reinforce the need for preventive intervention to protect vulnerable populations.

Heatwave-related morbidity in Australia: Effect modification by Individual and Area-level factors

Background

Heatwaves are associated with increases in mortality, emergency department visits, and hospital admissions. However, evidence regarding heatwave impacts on general practice (GP) visits is limited. The objectives of this study were to quantify the impact of heatwaves on GP visits in Australia and identify the individual and area-level factors that modify the heatwave-GP visits association.

Methods

Warm-season (October-March) GP visits data (2011-2016) were obtained from the Australian Bureau of Statistics. Using a case-crossover approach we assessed the effect of heatwaves (defined using Excess Heat Factor) on GP visits at the Statistical Area Level 2 (SA2) spatial unit (reflecting suburbs), as well as effect modification by individual and area-level factors. Results are reported as percent increase in GP visits during severe/extreme heatwaves compared with non-heatwaves.

Results

Nationally, GP visits increased by 4% (95%CI: 3-4%) during severe/extreme heatwaves. But impacts varied with the highest effect observed in Canberra (16.4%; 95%CI:15.4-17.4%), Adelaide (14.9%; 95%CI: 14.3-15.4%), and regional Victoria (13.5%; 95%CI: 13-14%). A gradient of impact was found within locations, for example, vulnerable SA2s nationally were featured by a higher proportion of populations with no air-conditioning, low income, limited English proficiency, living alone, and a prevalence of diabetes and circulatory diseases. Individual-level factors included those: living alone, with limited English proficiency, with diabetes, hypertension and using anti-coagulants and diuretic medications.

Conclusions

Heatwaves increase GP visits in Australia, with impacts varied between locations and populations, affecting certain areas and individuals disproportionately. Our results using an individual and area-level linked data suggest that local area and individual vulnerabilities should be incorporated when developing place-based interventions combating heatwave-health impacts.

Key messages

Heatwaves increase GP visits in Australia, but with spatial variability across and within locations. Individual and area-level factors contribute to heatwave-vulnerability.

Heatwave-related Mortality in Australia: Who's impacted the most?

Background

The impacts of heatwaves on the risk of mortality have been well-documented worldwide. However, impacts are not equally spread across the population with certain subgroups and locations affected more than others, warranting local evidence to guide and improve prevention and adaptation strategies. The objectives of this study were to identify the person and area-level socio-demographic, health, and environmental factors that modify the heatwave-mortality association in Australia.

Methods

Warm-season (October-March) mortality (2007-2017) were obtained from the Australian Bureau of Statistics. Heatwaves were defined using Excess Heat Factor, a normalised metric of heatwave severity. A time-stratified case-crossover design was used to model heatwave-mortality associations at the Statistical Areas 2 (SA2) spatial unit. Effect modification by person and area-level factors was assessed using interaction terms.

Results

Nationally, mortality increased by 2% (Relative Risk-RR 1.02; 95%CI: 1.01-1.03) during heatwaves with 1418 excess deaths (95%CI: 723-2113). But impacts varied with the highest effect observed in Adelaide (RR 1.08; 95%CI: 1.04-1.12) and Regional Tasmania (RR 1.11; 95%CI: 1.04-1.18). A gradient of impact was found within locations, for example, vulnerable SA2s in Adelaide were featured by a higher proportion of people in rental housing, inaccessibilities (vehicle and internet), low vegetation, newer houses, and a prevalence of respiratory and psychological diseases. Person-level factors included those: renting privately, with a low English-speaking ability, with chronic health conditions (diabetes, asthma/chronic obstructive pulmonary diseases) and using antidepressants, anxiolytics and sedative medications.

Conclusions

Our results, leveraging person and area-level linked data, highlight the need to consider contextual and individual risk factors and the importance of developing place-based targeted interventions to reduce heatwave health impacts.

Key messages

Heatwaves increase mortality in Australia. Heatwave-vulnerability is determined by individual and community-level factors.

Incidence Trends of Lip, Oral Cavity, and Pharyngeal Cancers: Global Burden of Disease 1990–2017

The worldwide incidence trends of the lip, oral cavity, and pharyngeal cancers (LOCPs) need to be updated. This study aims to examine the temporal incidence trends of LOCPs from 1990 to 2017, using the latest Global Burden of Disease (GBD) study data to explore sex, age, and regional differences. GBD incidence data for LOCPs were driven by population cancer registries and were estimated from mortality data. Age-standardized incidence rates (ASIRs) were directly extracted from the 2017 GBD database to calculate the estimated annual percentage change (EAPC) over the study period. Incidence trends are mapped and compared separately by sex (females vs. males), age groups (15–49, 50–69, and 70+ y), regions (21 geographical and 5 sociodemographic regions), and countries. Among 678,900 incident cases of LOCPs notified in 2017, more than half were lip and oral cavity cancers. From 1990 to 2017, the estimated global incidence for nasopharyngeal cancers decreased dramatically (EAPC = −1.52; 95% confidence interval [CI], –1.70 to −1.34), while the incidence for lip and oral cavity cancers (EAPC = 0.26; 95% CI, 0.16–0.37) and other pharyngeal cancers (EAPC = 0.62; 95% CI, 0.54–0.71) increased. Higher ASIRs were observed among males than females across all age groups. However, females had larger EAPC variation when compared to males. Population groups aged 15 to 49 y presented the lowest ASIRs, with larger values of EAPC than those aged 50 to 69 and 70+ y. While high-income countries had higher ASIRs with little EAPC variation, ASIRs varied across low/middle-income regions with larger EAPC variations. South Asia and East Asia had the highest ASIRs and EAPC for lip and oral cavity cancers, respectively. In conclusion, the global incidence of LOCPs has increased among females, those aged 15 to 49 y, and people from low/middle-income countries over the study period, excepting nasopharyngeal cancers, which had a decreasing worldwide trend.

The challenges of implementing an integrated One Health surveillance system in Australia

As 75 per cent of emerging infectious diseases are of animal origin, a One Health approach that integrates the health of humans, animals and the environment could provide an earlier opportunity for zoonotic disease detection and prevention. In Australia, human, animal and ecological health are managed by separate sectors with limited communication. This study aims to explore how professionals in these fields perceive a One Health approach to zoonotic disease surveillance, aiming to identify the challenges to the implementation of an integrated system in Australia. Using a qualitative research method, ten semistructured interviews were conducted with academic experts to gain insight into the possibility of developing an integrated surveillance system in Australia. A thematic analysis of the data was undertaken. Findings showed the absence of a clear definition and subsequent vision for the future of One Health act as a barrier to interdisciplinary collaboration, and that siloed approaches by different sectors restrict the ability for professionals to work collaboratively across disciplines. An understanding of disease transmission was considered by participants to be a necessary requirement for a successful One Health approach. Finally, participants considered political will an essential requirement for the integration of surveillance systems. This study demonstrates that for a One Health approach to be implemented in an Australian setting, those working in the fields of human, animal and ecological health must agree on several aspects. The establishment of a formal governance body with representatives from each sector could assist in overcoming long‐standing barriers of privacy and distrust. Further, developing interdisciplinary training in One Health concepts for medical, environmental and veterinary students may encourage cross‐disciplinary collaboration. Finally, demonstrating to policymakers the economic benefit of improved and timely detection of zoonoses may help in facilitating a structured One Health approach to disease surveillance in Australia.

Experts' Perceptions on China's Capacity to Manage Emerging and Re-emerging Zoonotic Diseases in an Era of Climate Change

Zoonotic diseases transmitted by arthropods and rodents are a major public health concern in China. However, interventions in recent decades have helped lower the incidence of several diseases despite the country's large, frequently mobile population and socio-economic challenges. Increasing globalization, rapid urbanization and a warming climate now add to the complexity of disease control and prevention and could challenge China's capacity to respond to threats of emerging and re-emerging zoonoses. To investigate this notion, face-to-face interviews were conducted with 30 infectious disease experts in four cities in China. The case study diseases under discussion were malaria, dengue fever and haemorrhagic fever with renal syndrome, all of which may be influenced by changing meteorological conditions. Data were analysed using standard qualitative techniques. The study participants viewed the current disease prevention and control system favourably and were optimistic about China's capacity to manage climate-sensitive diseases in the future. Several recommendations emerged from the data including the need to improve health literacy in the population regarding the transmission of infectious diseases and raising awareness of the health impacts of climate change amongst policymakers and health professionals. Participants thought that research capacity could be strengthened and human resources issues for front-line staff should be addressed. It was considered important that authorities are well prepared in advance for outbreaks such as dengue fever in populous subtropical areas, and a prompt and coordinated response is required when outbreaks occur. Furthermore, health professionals need to remain skilled in the identification of diseases for which incidence is declining, so that re-emerging or emerging trends can be rapidly identified. Recommendations such as these may be useful in formulating adaptation plans and capacity building for the future control and prevention of climate-sensitive zoonotic diseases in China and neighbouring countries.

The effects of air pollution on asthma hospital admissions in Adelaide, South Australia, 2003-2013: time-series and case-crossover analyses

BACKGROUND

Air pollution can have adverse health effects on asthma sufferers, but the effects vary with geographic, environmental and population characteristics. There has been no long time-series study in Australia to quantify the effects of environmental factors including pollen on asthma hospitalizations.

OBJECTIVES

This study aimed to assess the seasonal impact of air pollutants and aeroallergens on the risk of asthma hospital admissions for adults and children in Adelaide, South Australia.

METHODS

Data on hospital admissions, meteorological conditions, air quality and pollen counts for the period 2003-2013 were sourced. Time-series analysis and case-crossover analysis were used to assess the short-term effects of air pollution on asthma hospitalizations. For the time-series analysis, generalized log-linear quasi-Poisson and negative binomial regressions were used to assess the relationships, controlling for seasonality and long-term trends using flexible spline functions. For the case-crossover analysis, conditional logistic regression was used to compute the effect estimates with time-stratified referent selection strategies.

RESULTS

A total of 36,024 asthma admissions were considered. Findings indicated that the largest effects on asthma admissions related to PM_2.5 , NO₂ , PM₁₀ and pollen were found in the cool season for children (0-17 years), with the 5-day cumulative effects of 30.2% (95% CI: 13.4-49.6%), 12.5% (95% CI: 6.6-18.7%), 8.3% (95% CI: 2.5-14.4%) and 4.2% (95% CI: 2.2-6.1%) increases in risk of asthma hospital admissions per 10 unit increments, respectively. The largest effect for ozone was found in the warm season for children with the 5-day cumulative effect of an 11.7% (95% CI: 5.8-17.9%) increase in risk of asthma hospital admissions per 10 ppb increment in ozone level.

CONCLUSION

Findings suggest that children are more vulnerable and the associations between exposure to air pollutants and asthma hospitalizations tended to be stronger in the cool season compared to the warm season, with the exception of ozone. This study has important public health implications and provides valuable evidence for the development of policies for asthma management.

Meat Science and Muscle Biology Symposium: stem cell niche and postnatal muscle growth

Stem cell niche plays a critical role in regulating the behavior and function of adult stem cells that underlie tissue growth, maintenance, and regeneration. In the skeletal muscle, stem cells, called satellite cells, contribute to postnatal muscle growth and hypertrophy, and thus, meat production in agricultural animals. Satellite cells are located adjacent to mature muscle fibers underneath a sheath of basal lamina. Microenvironmental signals from extracellular matrix mediated by the basal lamina and from the host myofiber both impinge on satellite cells to regulate their activity. Furthermore, several types of muscle interstitial cells, including intramuscular preadipocytes and connective tissue fibroblasts, have recently been shown to interact with satellite cells and actively regulate the growth and regeneration of postnatal skeletal muscles. From this regard, interstitial adipogenic cells are not only important for marbling and meat quality, but also represent an additional cellular component of the satellite cell niche. At the molecular level, these interstitial cells may interact with satellite cells through cell surface ligands, such as delta-like 1 homolog (Dlk1) protein whose overexpression is thought to be responsible for muscle hypertrophy in callipyge sheep. In fact, extracellular Dlk1 protein has been shown to promote the myogenic differentiation of satellite cells. Understanding the cellular and molecular mechanisms within the stem cell niche that regulate satellite cell differentiation and maintain muscle homeostasis may lead to promising approaches to optimizing muscle growth and composition, thus improving meat production and quality.

Internet use and risk behaviours: an online survey of visitors to three gay websites in China

OBJECTIVES

To describe the risk behaviours of visitors to gay websites and to explore the role of the internet in the HIV transmission among the Chinese men who have sex with men (MSM).

METHODS

Between May and August 2006, visitors of three Chinese gay websites were invited to complete an online questionnaire about the use of the internet and risk sexual behaviours.

RESULTS

The median age of the online sample was 25 years old (range 18 to 64). Over three-quarters (77.6%) had an education of college or higher. Less than 44% of the online sample reported little or no risk for HIV transmission. These men had either had no anal intercourse (28.0%) or had always used a condom for anal intercourse (15.8%). Although only about half of the participants reported that their main purpose of visiting the gay websites was to look for sexual partners, most participants (86.1%) had used the internet to seek partners. Compared with men seeking sexual partners only on the internet, men seeking partners both in traditional gay venues and on the internet were older, less likely to be students and more likely to have unprotected anal intercourse, more than six sexual partners in the past 6 months and commercial sex behaviours.

CONCLUSION

The users of the gay websites are relatively young and well educated, and highly vulnerable to HIV/AIDS, given their low prevalence of consistent condom use and multiple-risk sexual behaviours. Effective intervention programmes should be implemented and strengthened in China, especially for those who seek sexual partners both on the internet and in traditional gay venues.

Weather: driving force behind the transmission of severe acute respiratory syndrome in China?

BACKGROUND

The association between weather and severe acute respiratory syndrome (SARS) transmission in Beijing and Hong Kong in the 2003 epidemic was studied to examine the effect of weather on SARS transmission.

METHODS

Pearson's correlation analyses and negative binomial regression analyses were used to quantify the correlations between the daily newly reported number of SARS cases and weather variables, using daily disease notification data and meteorological data from the two locations.

RESULTS

The results indicate that there were inverse association between the number of daily cases and maximum and/or minimum temperatures whereas air pressure was found to be positively associated with SARS transmission.

CONCLUSION

The study suggests that weather might be a contributory factor in the 2003 SARS epidemic, in particular in the transmission among the community members.

Advantages and challenges of using census and multiplier methods to estimate the number of female sex workers in a Chinese city

Using census and multiplier methods to estimate the size of the population of female sex workers (FSWs) in a small city in western China, this study compared the advantages and challenges of the two methods. It was estimated that there were about 1,500 FSWs within the urban area using the census method, which was significantly lower than that estimated by the multiplier method (2,500). Each method has advantages and limitations, and could be applied to different situations. The census method is less time and resource consuming in smaller regions and has a tendency to underestimate, and therefore, the result can be viewed as a low limit. It is useful in a local setting, for example, when estimations are needed for planning HIV/AIDS prevention programmes in a single city. Using existing information or resources, multiplier method could be used to produce estimates for a large geographic area or at a national level.

Are humans infected by Hantaviruses in Australia?

Hantavirus antibody-positive rodents have been found across Australia although, to date, there are no reports of infections in humans. This could be due to misdiagnosis clinically and/or inadequate laboratory technique/skills. There are close trading ties between Australia and Asian countries as well as our geographical neighbours where both human and rodent infections are found, so importation is a continuing threat. We consider that further sero-epidemiological surveys are warranted among rodents (especially those captured from ports in Australia), in patients from renal and respiratory wards of hospitals, and in residents and employees close to harbours using more specific and sensitive laboratory techniques than have been available in the past.

The prevalence of HCV antibody in South Australian prisoners

OBJECTIVES

The study was aimed at identifying the hepatitis C virus (HCV)-antibody status of prisoners incarcerated in South Australia in order to develop an HCV prevalence estimate for the whole prison system.

METHODS

The health records of persons incarcerated within eight prisons (accommodating approximately 93% of the jurisdiction's adult incarcerated population) were audited for evidence of HCV infection, age, sex, Indigenous status (Australian Aboriginal or Torres Strait Islander) and date of entry to prison. These data were analysed using both univariate and multivariate techniques.

RESULTS

Among 1347 prisoners (1254 males and 93 females), 30.2% were HCV-antibody positive. After excluding those with no history of testing, HCV-antibody prevalence rose to 41.3% (males 39.8%, females 66.1%). HCV-antibody positivity was significantly associated with age, sex and Indigenous status in both univariate and multivariate analyses.

CONCLUSIONS

Consistent with the literature, the prevalence of HCV infection in the SA prison system appears to be extremely high. This study suggests that HCV prevention efforts in prison settings should be considered as an important priority.

Occupational blood and body fluid exposure in an Australian teaching hospital

To examine work-related blood and body fluid exposure (BBFE) among health-care workers (HCWs), to explore potential risk factors and to provide policy suggestions, a 6-year retrospective study of all reported BBFE among HCWs (1998-2003) was conducted in a 430-bed teaching hospital in Australia. Results showed that BBFE reporting was consistent throughout the study period, with medical staff experiencing the highest rate of sharps injury (10.4%). Hollow-bore needles were implicated in 51.7% of all percutaneous injuries. Most incidents occurred during sharps use (40.4%) or after use but before disposal (27.1%). Nursing staff experienced 68.5% of reported mucocutaneous exposure. Many such exposures occurred in the absence of any protective attire (61.1%). This study indicated that emphasis on work practice, attire, disposal systems and education strategies, as well as the use of safety sharps should be employed to reduce work-related injuries among HCWs in Australia.

Trends in mortality rates for infectious and parasitic diseases in Australia: 1907-1997

AIMS

To characterize long-term mortality trends for infectious and parasitic diseases in Australia during the twentieth century, explore influencing factors and provide suggestions to health policy-makers.

METHODS

A descriptive study was conducted. Deaths due to communicable diseases from 1907 to 1997 were tallied, according to the International Classification of Diseases version 9 (ICD-9). Trends in infectious disease mortality in overall population and in the 0-4 years age group were examined and standardized by sex. Death rates were also studied for: (i) diarrhoea/enteritis, (ii) pneumonia and all respiratory diseases and (iii) tuberculosis.

RESULTS

There has been a substantial decline in -mortality from communicable diseases over the study period. The death rate dropped from 258.9 per 100,000 population in 1907 to 7.2 per 100,000 population in 1997. Six phases of the decline were observed.

CONCLUSIONS

A combination of improved living conditions and access to readily available treatments over the twentieth century played an important role in the reduction of infectious disease mortality in Australia.

Climate variability and Ross River virus transmission

OBJECTIVES

(1) To examine the feasibility to link climate data with monthly incidence of Ross River virus (RRv). (2) To assess the impact of climate variability on the RRv transmission.

DESIGN

An ecological time series analysis was performed on the data collected between 1985 to 1996 in Queensland, Australia.

METHODS

Information on the notified RRv cases was obtained from the Queensland Department of Health. Climate and population data were supplied by the Australian Bureau of Meteorology and the Australian Bureau of Statistics, respectively. Spearman's rank correlation analyses were performed to examine the relation between climate variability and the monthly incidence of notified RRv infections. The autoregressive integrated moving average (ARIMA) model was used to perform a time series analysis. As maximum and minimum temperatures were highly correlated with each other (r(s)=0.75), two separate models were developed.

RESULTS

For the eight major cities in Queensland, the climate-RRv correlation coefficients were in the range of 0.12 to 0.52 for maximum and minimum temperatures, -0.10 to 0.46 for rainfall, and 0.11 to 0.52 for relative humidity and high tide. For the whole State, rainfall (partial regression coefficient: 0.017 (95% confidence intervals 0.009 to 0.025) in Model I and 0.018 (0.010 to 0.026) in Model II), and high tidal level (0.030 (0.006 to 0.054) in Model I and 0.029 (0.005 to 0.053) in Model II) seemed to have played significant parts in the transmission of RRv in Queensland. Maximum temperature was also marginally significantly associated with the incidence of RRv infection.

CONCLUSION

Rainfall, temperature, and tidal levels may be important environmental determinants in the transmission cycles of RRv disease.

Geographic variation of notified Ross River virus infections in Queensland, Australia, 1985-1996

The spatial and temporal variations of Ross River virus infections reported in Queensland, Australia, between 1985 and 1996 were studied by using the Geographic Information System. The notified cases of Ross River virus infection came from 489 localities between 1985 and 1988, 805 between 1989 and 1992, and 1,157 between 1993 and 1996 (chi2(df = 2) = 680.9; P < 0.001). There was a marked increase in the number of localities where the cases were reported by 65 percent for the period of 1989-1992 and 137 percent for 1993-1996, compared with that for 1985-1988. The geographic distribution of the notified Ross River virus cases has expanded in Queensland over recent years. As Ross River virus disease has impacted considerably on tourism and industry, as well as on residents of affected areas, more research is required to explore the causes of the geographic expansion of the notified Ross River virus infections.

Family self-medication and antibiotics abuse for children and juveniles in a Chinese city

To identify the determinants of self-medication and antibiotics abuse by parents treating their children aged between 2 and 18 over the previous year, an investigation was conducted in Hefei City, China in April, 1995. A total of 1596 students from a kindergarten, a primary school and a high school were included in the study, and 1459 completed questionnaires were collected (the response rate: 91.4%). The results showed the rate of parental self-medication for their children in the sample was 59.4%. It increased with children's age; about 51% of children had received parental self-medication on six or more occasions during the 1-year period and 32.8% on four to five occasions; there were associations between parental self-prescribers and sources of medicine and severity of disease. The rate of antibiotics abuse was 35.7%. Logistic regression analysis showed that there were significant associations between self-medication and payment of the mother's medical fees by employers, severity of diseases as well as the mother's educational level.

[Determination of the aconitine alkaloids in traditional Chinese medicine chuanwu and caowu by high performance capillary electrophoresis(HPCE)]

A simple and rapid method for the simultaneous assay of three aconitine alkaloids (mesaconitine (MA), hypaconitine (HA) and aconitine (A) in the traditional Chinese medicines, Chuanwu and Caowu, by high performance capillary electrophoresis has been established, using tetracaine as an internal standard. The experimental conditions were as follows, the electrophoretic medium was composed of V[70 mmol/L Tris-borate (pH 8.49)]: V(methanol) = 60:40, uncoated capillary used was 50 cm x 50 microns i.d. and detection was carried out with a UV monitor at 235 nm. The separation was achieved by optimizing the cartridge temperature, the applied voltage, and the pH as well as the concentration of the buffer, and organic modifier. The calibration curve showed a good linearity in the mass concentration range of 0.0115-0.8330 g/L (r = 0.9996) for MA, 0.0089-0.6440 g/L (r = 0.9997) for HA, and 0.0083-0.6000 g/L(r = 0.9997) for A. The recoveries ranged from 93.0% to 104.0% with relative standard deviations from 0.68% to 1.7%. The total time for separation and determination was within 23 min. By means of this method, three aconitine alkaloids in Chuanwu and Caowu have been determined.

[Development of the IMP900 ECG & VT patient monitoring system]

A new respiration monitor was developed with this paper, which can monitor tidal volume continuously based on the impedance technique as well ad ECG at the same time. Advanced digital storage display technique and modular hardware design are adopted in this system. One by one calibration method was introduced to solve problem of individual differences in the measurement of tidal volume, which make it viable to monitor Tidal volume with impedance technique. The system possesses characteristic of high ratio of performance to cost. Clinical tests of the system have been made for nonsurgical patients, the results show that the system meets the basic clinical requirements, and its wide clinical applications are expected in the future.

Seasonal rainfall variability, the incidence of hemorrhagic fever with renal syndrome, and prediction of the disease in low-lying areas of China

To investigate determinants of hemorrhagic fever with renal syndrome (HFRS) in low-lying areas of China, the authors studied Chuigang and Wanggang communities in Anhui Province. These adjacent farming communities have a population of about 100,000. Data were collected from the two communities in 1961-1977 and from Yingshang County in 1983-1995; information covered the incidence of HFRS, amount of precipitation, differences in the water level of the Huai River, density of Apodemus agrarius, autumn crop production, and areas of inundated farmland. Correlation and multiple linear regression analyses were used to estimate the relation between seasonal rainfall, density of mice, occupational factors, and occurrence of the disease. Associations were observed between the incidence of HFRS and the amount of precipitation, the water level of the Huai River, and the areas of inundated farmland in Chuigang community. The smaller the water-level difference, the less farmland was inundated and the higher the incidence of HFRS. In Wanggang community, the density of A. agrarius (r1=0.63, p=0.02), the water-level difference in the Huai River (r2=-0.81, p=0.007), and crop production (r3=0.96, p=0.005) were correlated with the incidence of HFRS. The regression analyses based on Wanggang community suggested that these indexes could be used as predictive variables, and the results from the model were well calibrated with the actual incidence of HFRS in that community (R2=0.88, p < 0.01) and Yingshang County (R2=0.91, p < 0.01).

[An epidemiological study on the rate of becoming chronic in HCV infection]

Anti-HCV (+) and/or HCV RNA (+) were chosen for study on patients admitted to two provincial hospitals and "professional" blood donors in one of the areas in Anhui province in 1992-1996. Clinical diagnosis, treatment and epidemiology on HCV infection were retrospectively reviewed and in the meantime their present condition together with experimental data were studied; Chronic tendency on HCV infection of blood donors was described. Results showed that the rates of duration on becoming chronic for HCV infection were: six month later-55.93%, one year-50%, two-years-48.54%, three years-46.47% and four years-46.43%. Rate of becoming chronic after HCV infection was continuously in high level, then slowly decreasing, to 46%-48% in two years, still much higher than hepatitis B which had a rate of 5%-10% becoming chronic.

[The design of a novel multifunction ECG board]

In this paper an ECG amplifying circuit is comprehensively presented. This circuit has all the necessary functions which include isolated ground, programmable ECG lead and filter band, programmed gain, rapid baseline restoring, anti defibrillating electrical shock, anti interference of high frequency electrotome etc.