Molecular parasitology of malaria in Papua New Guinea

Research into the molecular biology of infectious diseases is mostly associated with well-developed countries. But in the midst of tropical Papua New Guinea, highly sophisticated molecular research has being conducted over years to understand and fight malaria and other tropical diseases. Here, we review such research carried out at the Papua New Guinea Institute of Medical Research. This Institute has considerably shaped research on molecular epidemiology through its analysis of the diversity and structure of the Plasmodium falciparum population. In addition, research has been conducted on human host factors and, more recently, the molecular analysis of drug resistance and the underlying molecular mechanisms of host-parasite interactions have been investigated.     

A varied pattern of change of the sex differential in survival in the G7 countries

Over the course of the 20th century the sex differential in life expectancy at birth in the industrialized countries has widened considerably in favour of women. Starting in the early 1970s, the beginning of a reversal in the long-term pattern of this differential has been noted in some high-income countries. This study documents a sustained pattern of narrowing of this measure into the later part of the 1990s for six of the populations that comprise the G7 countries: Canada, France, Germany, Italy, England and Wales (as representative of the United Kingdom) and USA. For Japan, a persistence of widening sex differences in survival is noted. The sex differences in life expectancy are decomposed over roughly three decades (early 1970s to late 1990s) from the point of view of four major cause-of-death categories: circulatory diseases, cancers, accidents/violence/suicide, and 'other' (residual) causes. In the six countries where the sex gap has narrowed, this has resulted primarily from reduced sex differences in circulatory disease mortality, and secondarily from reduced differences in male and female death rates due to accidents, violence and suicide combined. In some of the countries sex differentials in cancer mortality have been converging lately, and this has also contributed to a narrowing of the difference in life expectancy. In Japan, males have been less successful in reducing their survival disadvantage in relation to Japanese women with regard to circulatory disease and cancer; and in the case of accidents/violence/suicide, male death rates increased during the 1990s. These trends explain the divergent pattern of the sex difference in life expectation in Japan as compared with the other G7 nations.     

The reversal of fortunes: trends in county mortality and cross-county mortality disparities in the United States

Background

Counties are the smallest unit for which mortality data are routinely available, allowing consistent and comparable long-term analysis of trends in health disparities. Average life expectancy has steadily increased in the United States but there is limited information on long-term mortality trends in the US counties This study aimed to investigate trends in county mortality and cross-county mortality disparities, including the contributions of specific diseases to county level mortality trends.

Methods and Findings

We used mortality statistics (from the National Center for Health Statistics [NCHS]) and population (from the US Census) to estimate sex-specific life expectancy for US counties for every year between 1961 and 1999. Data for analyses in subsequent years were not provided to us by the NCHS. We calculated different metrics of cross-county mortality disparity, and also grouped counties on the basis of whether their mortality changed favorably or unfavorably relative to the national average. We estimated the probability of death from specific diseases for counties with above- or below-average mortality performance. We simulated the effect of cross-county migration on each county''s life expectancy using a time-based simulation model. Between 1961 and 1999, the standard deviation (SD) of life expectancy across US counties was at its lowest in 1983, at 1.9 and 1.4 y for men and women, respectively. Cross-county life expectancy SD increased to 2.3 and 1.7 y in 1999. Between 1961 and 1983 no counties had a statistically significant increase in mortality; the major cause of mortality decline for both sexes was reduction in cardiovascular mortality. From 1983 to 1999, life expectancy declined significantly in 11 counties for men (by 1.3 y) and in 180 counties for women (by 1.3 y); another 48 (men) and 783 (women) counties had nonsignificant life expectancy decline. Life expectancy decline in both sexes was caused by increased mortality from lung cancer, chronic obstructive pulmonary disease (COPD), diabetes, and a range of other noncommunicable diseases, which were no longer compensated for by the decline in cardiovascular mortality. Higher HIV/AIDS and homicide deaths also contributed substantially to life expectancy decline for men, but not for women. Alternative specifications of the effects of migration showed that the rise in cross-county life expectancy SD was unlikely to be caused by migration.

Conclusions

There was a steady increase in mortality inequality across the US counties between 1983 and 1999, resulting from stagnation or increase in mortality among the worst-off segment of the population. Female mortality increased in a large number of counties, primarily because of chronic diseases related to smoking, overweight and obesity, and high blood pressure.     

Assessing the contribution of age-sex differentials in causes of death due to infectious and parasitic diseases to the trends in age-sex differentials in life expectancy in Mauritius

This study applies two methodologies to Mauritian life tables and cause-of-death data: (1) the decomposition of sex differentials in life expectancy using Arriaga's approach and (2) the estimation of the effect of marginal reduction in deaths from infectious and parasitic diseases on life expectancy using Keyfitz's methodology on cause-specific entropy and that of Nanjo. The findings in this paper support earlier findings about the importance of the period 1969-1976 in the mortality transition in Mauritius, a period in which sex differentials in life expectancies reached a peak level. The results suggest that the driving force behind those sex differentials in life expectancy was the sex differential in mortality in infectious and parasitic diseases, first among the young (ages below 10 years) and second among the older population (ages above 50 years). If the decline in mortality due to infectious and parasitic diseases was differentially greater in the older ages compared to the younger ages, that difference would have gone a long way toward reducing the magnitude of the historic peak sex differential in life expectancy achieved in 1976.     

Demographic and health patterns in a rural community from the Basque area in Spain (1800-1990)

In this work, the evolution of demographic and health patterns in a Basque rural population from Spain is analysed, as they relate to progress in demographic and epidemiological transition. For this purpose, parochial record data on 13,298 births and 9,215 deaths, registered during the 19th and 20th centuries (1800-1990), were examined. The study area is a rural community called Lanciego, which is located at the southern end of the Rioja Alavesa area (Alava Province, Basque Country). In Lanciego, demographic transition began in the final decade of the 19th century, when a definite, irreversible trend began towards a reduction in mortality. The decrease in the birth rate came later than that in the death rate, and did not start until the 1930s. The post-transitional stage seemed to be reached in the 1970s, when the birth and death rates showed values below 20 per 1,000. Other characteristics observed for the post-transitional stage in Lanciego are: (i) very low rates of infant mortality achieved at the expense of effective control of exogenous mortality; (ii) the mortality curve by ages changes from a U-shape (typical of populations with a high infant mortality rate and low life expectancy at birth) to a J-shape more characteristic of modern societies where longevity and life expectancy are considerably higher; (iii) a certain level of over-mortality among women in the senior age group (>65); and (iv) a significant proportion of mortality in recent times (1970-90) resulting from cardiovascular diseases and malignant neoplasms (post-transition causes). This last point is in contrast with observations from the first four decades of the 20th century, when infectious diseases and respiratory ailments were determining factors in mortality among this population. The data provided by the study of the variation over time in demographic and health patterns indicate that reducing the risk of mortality is one of the most important preconditions for fertility decline.     

An extraordinary life span estimate for the clown anemonefish Amphiprion percula

A population of the clown anemonefish Amphiprion percula was studied for 1 year, in Madang Lagoon, Papua New Guinea. From this study, data on mortality events and social structure were used to construct a stage-structured matrix model and estimate the average age at death (life expectancy) of various classes of individuals. Based on this model, it is estimated that the life expectancy of female A. percula , the oldest individuals in the population, is 30 years. This estimate is two times greater than the longevity estimated for any other coral reef damselfish and six times greater than the longevity expected for a fish of that size. The result complements the growing body of evidence, from widespread taxa, that organisms subject to low levels of extrinsic mortality show retarded senescence and increased longevity. It is suggested that fishes would be an excellent group for a broad scale comparative test of the predictions of the evolutionary theory of ageing.     

Life Expectancy and Death by Diseases of the Circulatory System in Patients with Bipolar Disorder or Schizophrenia in the Nordic Countries

Objective

Excess mortality from diseases and medical conditions (natural death) in persons with psychiatric disorders has been extensively reported. Even in the Nordic countries with well-developed welfare systems, register based studies find evidence of an excess mortality. In recent years, cardiac mortality and death by diseases of the circulatory system has seen a decline in all the Nordic countries, but a recent paper indicates that women and men in Denmark, Finland, and Sweden, who had been hospitalised for a psychotic disorder, had a two to three-fold increased risk of dying from a cardiovascular disease. The aim of this study was to compare the mortality by diseases of the circulatory system among patients with bipolar disorder or schizophrenia in the three Nordic countries Denmark, Sweden, and Finland. Furthermore, the aim was to examine and compare life expectancy among these patients. Cause specific Standardized Mortality Rates (SMRs) were calculated for each specific subgroup of mortality. Life expectancy was calculated using Wiesler’s method.

Results

The SMR for bipolar disorder for diseases of the circulatory system was approximately 2 in all countries and both sexes. SMR was slightly higher for people with schizophrenia for both genders and in all countries, except for men in Denmark. Overall life expectancy was much lower among persons with bipolar disorder or schizophrenia, with life expectancy being from 11 to 20 years shorter.

Conclusion

Our data show that persons in the Nordic countries with schizophrenia or bipolar disorder have a substantially reduced life expectancy. An evaluation of the reasons for these increased mortality rates should be prioritized when planning healthcare in the coming years.     

Whole-Genome Sequences and Comparative Genomics of Salmonella enterica Serovar Typhi Isolates from Patients with Fatal and Nonfatal Typhoid Fever in Papua New Guinea

Many of the developing countries of the Southeast Asian region are significantly affected by endemic typhoid fever, possibly as a result of marginal living standards. It is an important public health problem in countries such as Papua New Guinea, which is geographically close to some of the foci of endemicity in Asia. The severity of the disease varies in different regions, and this may be attributable to genetic diversity among the native strains. Genome sequence data on strains from different countries are needed to clearly understand their genetic makeup and virulence potential. We describe the genomes of two Salmonella Typhi isolates from patients with fatal and nonfatal cases of typhoid fever in Papua New Guinea. We discuss in brief the underlying sequencing methodology, assembly, genome statistics, and important features of the two draft genomes, which form an essential step in our functional molecular infection epidemiology program centering on typhoid fever. The comparative genomics of these and other isolates would enable us to identify genetic rearrangements and mechanisms responsible for endemicity and the differential severity of pathogenic salmonellae in Papua New Guinea and elsewhere.     

A divergent pattern of the sex difference in life expectancy: Sweden and Japan, early 1970s-late 1990s

For most of the 20th century the sex gap in life expectancy in the industrialized countries has widened in favor of women. By the early 1980s a reversal in the long-term pattern of this differential had occurred in some countries, where it reached a maximum and thereafter followed a declining trend. Of particular interest to the present investigation is the anomalous experience of Japan, where unlike other high-income countries the female advantage in life expectancy has been expanding. We contrast the case of Japan with that of Sweden, where, like many other high-income nations, the sex differential in longevity has been narrowing in recent years. We observe that in Sweden, until the early 1980s, the sex gap in life expectancy (female-male) exceeded that of Japan; but this situation reversed in subsequent periods, when the Swedish differential narrowed and that of Japan widened. A decomposition analysis indicates that these divergent patterns since 1980 have resulted mainly from larger than expected reductions in male mortality in Sweden due to heart disease and from accidents and violence, lung cancer and "other" cancers. In Japan, death rates for men and women from heart disease--which is a leading cause of death--have tended to decline more or less at the same pace since the early 1980s; and with regard to lung cancer, and "other" neoplasms, male death rates in Japan have been rising while those of women have either declined or risen more slowly. Moreover, during the 1990s, male and female suicide rates rose in Japan, but the rates for men went up faster. Altogether, the net effect of these divergent mortality trends for men and women in Japan underlie much of the observed widening of its sex differential in longevity in recent years.     

Sex differences in bone loss--an evolutionary perspective on a clinical problem

The dramatic increase in the world's population that has occurred over the past 100 years has come largely through reductions in death due to infectious disease. An epidemiologic transition to a preponderance of deaths due to degenerative conditions such as cardiovascular disease and cancer is occurring in the developing countries as well as in the industrialized ones. In the industrialized countries, demographic profiles now reflect the increased life expectancies of both sexes. However, female life expectancies exceed male by six or more years. Further change in mortality patterns will accompany success in the reduction of the number of mortalities attributable to such degenerative conditions as cardiovascular disease and cancer. In the 21st century, conditions associated with sensescence will be of increasing concern. Adaptive strategies that enhanced reproductive success throughout most of human evolution may now prove detrimental to human health as average life expectancies reach unprecedented length. In this environment, differences in the survival mechanisms deployed by males as opposed to females will become increasingly important.     

Health research in Papua New Guinea

The Papua New Guinea Institute of Medical Research (PNGIMR) is one of the most respected health research institutions in the developing world, and its studies of the local health problems of PNG have consistently had international relevance. This article examines the structural and philosophical factors that have enabled the success of the PNGIMR, and presents the PNGIMR approach to research as a potential model for other disease-endemic countries. An overview of PNGIMR research into malaria and filariasis is given with selected examples as an introduction to a Trends in Parasitology series on health research in Papua New Guinea.     

Measuring the health of nations: analysis of mortality amenable to health care

Objective To assess whether and how the rankings of the world''s health systems based on disability adjusted life expectancy as done in the 2000 World Health Report change when using the narrower concept of mortality amenable to health care, an outcome more closely linked to health system performance.Design Analysis of mortality amenable to health care (including and excluding ischaemic heart disease).Main outcome measure Age standardised mortality from causes amenable to health careSetting 19 countries belonging to the Organisation for Economic Cooperation and Development.Results Rankings based on mortality amenable to health care (excluding ischaemic heart disease) differed substantially from rankings of health attainment given in the 2000 World Health Report. No country retained the same position. Rankings for southern European countries and Japan, which had performed well in the report, fell sharply, whereas those of the Nordic countries improved. Some middle ranking countries (United Kingdom, Netherlands) also fell considerably; New Zealand improved its position. Rankings changed when ischaemic heart disease was included as amenable to health care.Conclusion The 2000 World Health Report has been cited widely to support claims for the merits of otherwise different health systems. High levels of health attainment in well performing countries may be a consequence of good fortune in geography, and thus dietary habits, and success in the health effects of policies in other sectors. When assessed in terms of achievements that are more explicitly linked to health care, their performance may not be as good.     

Bats Without Borders: Long-Distance Movements and Implications for Disease Risk Management

Fruit bats of the genus Pteropus (commonly known as flying-foxes) are the natural hosts of several recently emerged zoonotic viruses of animal and human health significance in Australia and Asia, including Hendra and Nipah viruses. Satellite telemetry was used on nine flying-foxes of three species (Pteropus alecto n = 5, P. vampyrus n = 2, and P. neohibernicus n = 2) to determine the scale and pattern of their long-distance movements and their potential to transfer these viruses between countries in the region. The animals were captured and released from six different locations in Australia, Papua New Guinea, Indonesia, and Timor-Leste. Their movements were recorded for a median of 120 (range, 47–342) days with a median total distance travelled of 393 (range, 76–3011) km per individual. Pteropus alecto individuals were observed to move between Australia and Papua New Guinea (Western Province) on four occasions, between Papua New Guinea (Western Province) and Indonesia (Papua) on ten occasions, and to traverse Torres Strait on two occasions. Pteropus vampyrus was observed to move between Timor-Leste and Indonesia (West Timor) on one occasion. These findings expand upon the current literature on the potential for transfer of zoonotic viruses by flying-foxes between countries and have implications for disease risk management and for the conservation management of flying-fox populations in Australia, New Guinea, and the Lesser Sunda Islands.     

Culture change and epidemiological patterns among the Hagahai,Papua New Guinea

The role of introduced epidemic disease in highland New Guinea is considered in light of recent debate concerning pre-contact adaptations. Seroepidemiological studies of the Hagahai, a small isolated group of hunterhorticulturalists in the fringe highlands of Papua New Guinea, document the recent introduction of mumps, hepatitis B, specific types of influenza, and rotavirus. Results are related to ethnographic findings, detailing past levels of intergroup contact and recent changes in settlement patterns, travel, feasting, health care, and other cultural factors. Data suggest that intergroup disease transmission is greatly increased decades before officially recorded time of contact and that mortality levels documented soon thereafter are not indicative of the pre-contact adaptation.     

The State of Health in Older Adults in Japan: Trends in Disability,Chronic Medical Conditions and Mortality

Both life expectancy and healthy life expectancy in Japan have been increasing and are among the highest in the world, but the gap between them has also been widening. To examine the recent trends in old age disability, chronic medical conditions and mortality in Japan, we retrospectively analyzed three nationally representative datasets: Comprehensive Survey of Living Conditions (2001–2013), Patient Survey (1996–2011) and Vital Statistics (1995–2010). We obtained the sex- and age-stratified trends in disability rate, treatment rates of nine selected chronic medical conditions (cerebrovascular diseases, joint disorders, fractures, osteoporosis, ischemic heart disease, diabetes mellitus, hypertension, pneumonia and malignant neoplasms), total mortality rate and mortality rates from specific causes (cerebrovascular diseases, heart diseases, pneumonia and malignant neoplasms) in both sexes in four age strata (65–69, 70–74, 75–79, 80–84 years). Disability rates declined significantly in both sexes. Treatment rates of all selected medical conditions also decreased significantly, except for fractures in women and pneumonia. Both total mortality rate and cause-specific mortality rates decreased in both sexes. We concluded that the recent decline in disability rates, treatment rates of chronic medical conditions and mortality rates points toward overall improvement in health conditions in adults over the age of 65 years in Japan. Nonetheless, considering the increase in the number of older adults, the absolute number of older adults with disability or chronic medical conditions will continue to increase and challenge medical and long-term care systems.     

Socioeconomic factors affecting the longevity of the Japanese population: a study for 1980 and 1985.

The effects of urbanisation, low income and rejuvenation of the population on life expectancy at birth and at 20, 40 and 65 years of age for males and females in Japan were examined twice, in 1980 and 1985. For males, urbanisation was the major factor determining life expectancy at birth and at age 20 years, and low income was the key determinant of decreased life expectancy except at 65 years of age. For females high income was the factor significantly decreasing life expectancy at 65 years of age in 1980, and rejuvenation of the population inversely influenced life expectancy except at birth in 1985. Life expectancy for all age groups in 1985 was significantly longer than in 1980 for both males and females.     

All Africa conference on tobacco control.

Although the health hazards of smoking are now generally accepted in most Western countries, the arguments have not had much impact on poorer nations. A conference on tobacco control held in Harare, Zimbabwe, in November last year was the largest to tackle this problem. The conference heard how threats of epidemics of tobacco related disease in the distant future held little weight with governments of countries that often already had massive public health problems. More immediate effects needed to be emphasised. Speakers gave three cogent arguments; firstly, the loss of capacity for foreign trade in essential goods, since most African countries are net importers of tobacco; secondly, the extensive deforestation which is occurring to fuel the flue curing of tobacco; thirdly, evidence from Papua New Guinea that raising taxation on tobacco provides governments with increased income for many years before a decrease begins.     

Navajo tribal mortality: A life table analysis of the leading causes of death

Abstract

The five leading causes of death for Navajo males and females are analyzed by life table methods. Navajo male and female life expectancy at birth were 58.8 and 71.8 years, respectively. The greatest increase in Navajo male life expectancy would result from the elimination of motor vehicle accidents (5.17 years at birth, and 3.11 years for working ages 15–65). The life expectancy of Navajo females would be lengthened the most (3.70 years) by elimination of circulatory system disease. For working‐ages gains for both sexes, however, the greatest benefit would result from elimination of motor vehicle accidents. The implications of the results are discussed in relation to the various public health programs and health planning efforts for the Navajo Nation.     

Health and the city: physical health and mental health

In France, city size has very little bearing on the mortality rate as a function of age and life expectancy and it is in large cities that these indicators are the most favorable. No increase in maternal or infant mortality rates or deaths due to cancers has been observed in large cities. The lower mortality rate linked to respiratory and cardiovascular diseases in large urban areas contradicts the fears concerning the impact of air pollution. Deaths linked to lifestyle are less frequent in big cities, which could be due to social structures (socio-professional level: the proportion of white-collar workers and professionals is higher in bigger cities than in the suburbs or small cities). However, although the overall mortality rate is lower, it should be emphasized that there is in large cities a greater incidence of sexually transmitted diseases, AIDS and certain infectious diseases (because of social diversity and the fact that certain individuals seeking anonymity and marginality are drawn to large cities). In terms of mental health, the breakdown of family structures, instability, unemployment, the lack of parental authority and failing schools render adolescents vulnerable and hinder their social integration. When the proportion of adolescents at risk is high in a neighborhood, individual problems are amplified and social problems result. In order to restore mental and social health to these neighborhoods, ambitious strategies are necessary which take into account family and social factors as well as environmental ones. At the present time, when physical health is constantly improving, the most pressing problems are those related to lifestyle and mental health which depend for a large part on social factors.     

Studies of the incidence, severity and distribution of false rust (Synchytrium psophocarpi), leaf spot (Pseudocercospora psophocarpi) and powdery mildew (Oidium sp.) on winged bean (Psophocarpus tetragonolobus) in Papua New Guinea

The incidence, severity and distribution of false rust, (Synchytrium psophocarpi), leaf spot (Pseudocercospora psophocarpi) and powdery mildew (Oidium sp.) on winged beans (Psophocarpus tetragonolobus) were evaluated on pure lines and mixed stands grown in Papua New Guinea between 1976 and 1978. Almost all of the 148 pure lines were susceptible to false rust and leaf spot and the incidence of these diseases increased with plant age. Standard area diagrams were superior to disease keys in evaluating disease severity. Levels of false rust on 10 promising agronomic lines differed according to the locality where the lines were grown. Two Thai lines showed resistance to false rust but P. scandens was immune to false rust and leaf spot. Surveys of 51 sites containing mixed stands of winged beans in the Eastern Highlands, Western Highlands, East New Britain, East Sepik, Madang and Morobe Provinces of Papua New Guinea indicated that leaf spot and false rust were present in both the wet and dry seasons and the apparent absence of disease was probably due to time and size of samples. The diseases appeared to be present in all the traditional winged bean growing areas of Papua New Guinea. It was difficult to obtain evidence of differences in palatability of tissues infected with false rust. The value of surveys and disease assessment in relation to evaluation of crop losses of winged bean caused by these pathogens and selection for resistance is discussed.