Disease and fertility: Evidence from the 1918–19 influenza pandemic in Sweden

What are the consequences of a severe health shock like an influenza pandemic on fertility? Using rich administrative data and a difference-in-differences approach, we evaluate fertility responses to the 1918–19 influenza pandemic in Sweden. We find evidence of a small baby boom following the end of the pandemic, but we show that this effect is second-order compared to a strong long-term negative fertility effect. Within this net fertility decline there are compositional effects: we observe a relative increase in births to married women and to better-off families. Several factors – including disruptions to the marriage market and income effects – contribute to the long-term fertility reduction. The results are consistent with studies that find a positive fertility response following natural disasters, but we show that this effect is short-lived.     

Lessons learned from the 1918–1919 influenza pandemic

The 1918 influenza pandemic was one of the most virulent strains of influenza in history. Phylogenic evidence of the novel H1N1 strain of influenza discovered in Mexico last spring (2009) links it to the 1918 influenza strain. With information gained from analyzing viral genetics, public health records and advances in medical science we can confront the 2009 H1N1 influenza on a global scale. The paper analyses the causes and characteristics of a pandemic, and major issues in controlling the spread of the disease. Wide public vaccination and open communication between government and health sciences professionals will be an essential and vital component in managing the 2009 H1N1 pandemic and any future pandemics.     

Can photoperiod predict mortality in the 1918-1920 influenza pandemic?

Amplitude of the seasonal change in day length increases with distance from the equator, and changes in day length markedly alter immune function in diverse nonhuman animal models of infection. Historical records of mortality data, ambient temperature, population density, geography, and economic indicators from 42 countries during 1918-1920 were analyzed to determine relative contributions toward human mortality during the "Spanish" influenza pandemic of 1918-1920. The data identify a strong negative relation between distance from the equator and mortality during the 1918-1920 influenza pandemic, which, in a multiple regression model, manifested independent of major economic, demographic, and temperature variables. Enhanced survival was evident in populations that experienced a winter nadir day length ≤10 h light/day, relative to those that experienced lower amplitude changes in photoperiod. Numerous reports indicate that exposure to short day lengths, typical of those occurring outside the tropics during winter, yields robust and enduring reductions in the magnitude of cytokine, febrile, and behavioral responses to infection. The present results are preliminary but prompt the conjecture that, if similar mechanisms are operant in humans, then they would be predicted to mitigate symptoms of infection in proportion to an individual's distance from the equator. Although limitations and uncertainties accompany regression-based analyses of historical epidemiological data, latitude, per se, may be an underrecognized factor in mortality during the 1918-1920 influenza pandemic. The author proposes that some proportion of the global variance in morbidity and mortality from infectious diseases may be explained by effects of day length on the innate immune response to infection.     

What explains cross-city variation in mortality during the 1918 influenza pandemic? Evidence from 438 U.S. cities

Disparities in cross-city pandemic severity during the 1918 Influenza Pandemic remain poorly understood. This paper uses newly assembled historical data on annual mortality across 438 U.S. cities to explore the determinants of pandemic mortality. We assess the role of three broad factors: i) pre-pandemic population health and poverty, ii) air pollution, and iii) the timing of onset and proximity to military bases. Using regression analysis, we find that cities in the top tercile of the distribution of pre-pandemic infant mortality had 21 excess deaths per 10,000 residents in 1918 relative to cities in the bottom tercile. Similarly, cities in the top tercile of the distribution of proportion of illiterate residents had 21.3 excess deaths per 10,000 residents during the pandemic relative to cities in the bottom tercile. Cities in the top tercile of the distribution of coal-fired electricity generating capacity, an important source of urban air pollution, had 9.1 excess deaths per 10,000 residents in 1918 relative to cities in the bottom tercile. There was no statistically significant relationship between excess mortality and city proximity to World War I bases or the timing of onset. In a counterfactual analysis, the three statistically significant factors accounted for 50 percent of cross-city variation in excess mortality in 1918.     

Simulating the effect of quarantine on the spread of the 1918–19 flu in Central Canada

Quarantine is often proposed and sometimes used to control the spread of infectious diseases through a human population. Yet there is usually little or no information on the effectiveness of attempting to quarantine humans that is not of an anecdotal or conjectural nature. This paper describes how a compartmental model for the geographic spread of infectious diseases can be used to address the potential effectiveness of human quarantine. The model is applied to data from the historical record in central Canada around the time of the 1918–19 influenza epidemic. Information on the daily mobility patterns of individuals engaged in the fur trade throughout the region prior to, during, and immediately after the epidemic are used to determine whether rates of travel were affected by informal quarantine policies imposed by community leaders. The model is then used to assess the impact of observed differences in travel on the spread of the epidemic. Results show that when mobility rates are very low, as in this region, quarantine practices must be highly effective before they alter disease patterns significantly. Simulation results suggest, though, that effectiveness varies depending on when the limitation on travel between communities is implemented and how long it lasts, and that a policy of introducing quarantine at the earliest possible time may not always lead to the greatest reduction in cases of a disease.     

Characterization of H9 subtype influenza viruses from the ducks of southern China: a candidate for the next influenza pandemic in humans?

A current view of the emergence of pandemic influenza viruses envisages a gene flow from the aquatic avian reservoir to humans via reassortment in pigs, the hypothetical "mixing vessel." Understanding arising from recent H5N1 influenza outbreaks in Hong Kong since 1997 and the isolation of avian H9N2 virus from humans raises alternative options for the emergence of a new pandemic virus. Here we report that H9N2 influenza viruses established in terrestrial poultry in southern China are transmitted back to domestic ducks, in which the viruses generate multiple reassortants. These novel H9N2 viruses are double or even triple reassortants that have amino acid signatures in their hemagglutinin, indicating their potential to directly infect humans. Some of them contain gene segments that are closely related to those of A/Hong Kong/156/97 (H5N1/97, H5N1) or A/Quail/Hong Kong/G1/97 (G1-like, H9N2). More importantly, some of their internal genes are closely related to those of novel H5N1 viruses isolated during the outbreak in Hong Kong in 2001. This study reveals a two-way transmission of influenza virus between terrestrial and aquatic birds that facilitates the generation of novel reassortant H9N2 influenza viruses. Such reassortants may directly or indirectly play a role in the emergence of the next pandemic virus.     

From pandemic to endemic: Spatial-temporal patterns of influenza-like illness incidence in a Swiss canton, 1918–1924

In pandemics, past and present, there is no textbook definition of when a pandemic is over, and how and when exactly a respiratory virus transitions from pandemic to endemic spread. In this paper we have compared the 1918/19 influenza pandemic and the subsequent spread of seasonal flu until 1924. We analysed 14,125 reports of newly stated 32,198 influenza-like illnesses from the Swiss canton of Bern. We analysed the temporal and spatial spread at the level of 497 municipalities, 9 regions, and the entire canton. We calculated incidence rates per 1000 inhabitants of newly registered cases per calendar week. Further, we illustrated the incidences of each municipality for each wave (first wave in summer 1918, second wave in fall/winter 1918/19, the strong later wave in early 1920, as well as the two seasonal waves in 1922 and 1924) on a choropleth map. We performed a spatial hotspot analysis to identify spatial clusters in each wave, using the Gi* statistic. Furthermore, we applied a robust negative binomial regression to estimate the association between selected explanatory variables and incidence on the ecological level. We show that the pandemic transitioned to endemic spread in several waves (including another strong wave in February 1920) with lower incidence and rather local spread until 1924 at least. At the municipality and regional levels, there were different patterns of spread both between pandemic and seasonal waves. In the first pandemic wave in summer 1918 the probability of higher incidence was increased in municipalities with a higher proportion of factories (OR 2.60, 95%CI 1.42–4.96), as well as in municipalities that had access to a railway station (OR 1.50, 95%CI 1.16–1.96). In contrast, the strong fall/winter wave 1918 was very widespread throughout the canton. In general, municipalities at higher altitude showed lower incidence. Our study adds to the sparse literature on incidence in the 1918/19 pandemic and subsequent years. Before Covid-19, the last pandemic that occurred in several waves and then became endemic was the 1918–19 pandemic. Such scenarios from the past can inform pandemic planning and preparedness in future outbreaks.     

Convincing the “Herd” of immunity: Lessons from smallpox vaccination in 19th century Germany

Although vaccination is a cost-effective way to control infectious diseases, it is often met with popular resistance. Studying smallpox in 19th century Germany, this paper explores how economic incentives contribute to this phenomenon. The paper adds to the literature by combining mathematical epidemiology and unpublished archival evidence from two German states - Baden and Wurttemberg. The two states are an intriguing case because their initial conditions and vaccination laws were similar. Despite this, Baden experienced lower smallpox prevalence and higher vaccination uptake than Wurttemberg. The epidemiological model predicts that incentives to vaccinate decline rapidly when immunization reduces prevalence. The archival evidence reveals that Baden offset this decline by creating a public vaccination system which reduced costs for vaccinees and vaccinators alike. This suggests that the high fixed costs of centralized immunization policies can be compensated by economies of scale and popular acceptance.     

Biologists and the promotion of birth control research, 1918–1938

Conclusions In spite of these efforts in the 1920s and 1930s to initiate ongoing research on contraception, the subject of birth control remained a problem of concern primarily to the social activist rather than to the research scientist or practicing physician.⁸⁰ In the 1930s, as has been shown, American scientists turned to the study of other aspects of reproductive physiology, while American physicians, anxious to eliminate the moral and medical dangers of contraception, only reluctantly accepted birth control as falling within their professional domain.As a result, the problem of cheap, effective, and safe contraception was not solved by these earliest attempts. Consideration of the subject was initiated afresh by private philanthropy after World War II, sparked by a new wave of interest in population studies.⁸¹ Summarizing such efforts to support research in the reproductive sciences, a recent Ford Foundation study has noted: To initiate and sustain serious research in the reproductive sciences has required for more than half a century concerted effort by interested individuals and private organizations, mainly from outside the mainstreams of the biomedical research community.⁸² The early laboratory research on chemical contraception described in this paper was but one important outcome of the concerted effort made by reformers in the 1920s to eliminate a variety of social problems thought to derive from excessive fertility. Scientific arguments and expertise were employed to advocate reform as well as to define the appropriate solution to such social problems. Scientists were recruited as advocates for the movement, but they were also employed as researchers in laboratory investigations sponsored by these same reformers.Sponsors of these early laboratory studies noted the difficulty of obtaining first-class investigators.⁸³ The routine analyses necessary for such research, as well as the traditional scientific aversion to applied problems, provide only a partial explanation for this response. The real difficulty lay in recruiting investigators to a field (reproduction and human sexuality) that had previously been taboo. Once opened up — first as socially relevant, and finally as scientifically sound — there was much interest in this area, and the appeal to researchers of the scientific issues surrounding fertility and reproduction soon surpassed that of the reforming value of birth control.A survey of the kinds of experimental investigations sponsored by birth control advocates indicates the range of physiological problems explored by contraceptive research. The most definitive work was done on the efficacy and safety of spermicides, but the potential of other contraceptive methods was also examined. Investigators attempted to develop spermatoxins that would effectively immunize women against sperm, and they also tried to elucidate the mechanism of hormonal control of reproduction. In fact, speculations about the possible hormonal manipulation of fertility were expressed at the Seventh International Birth Control Conference held in Zurich in 1930.⁸⁴ In the 1920s, clinical studies were undertaken to assess the effectiveness of the various birth control methods. Laboratory investigators complemented this work by screening spermicides for safety and testing for their ability to kill sperm. There were a variety of birth control preparations on the market (most of which were sold as feminine hygiene products), but no one really knew whether these were effective or even safe.⁸⁵ Although the physiology of other major organ systems was well advanced, the scientific study of reproductive physiology and contraceptive technology was clearly in its infancy in this period. Routine analyses simply could not be conducted, because the fundamental research establishing baselines had not yet been done. Scientists used this fact to redirect attention to basic research on reproduction.Laboratory research on contraception indicated important unexplored areas for physiological investigation. Social activists, who had encouraged prominent scientists to become interested in both the social value and the genetic implications of birth control, found these investigators revising the goals of their research. The biologists had formed their own network and had begun to seek out funding, reformulating the justification for sponsorship of further investigations. The eugenic motivations underlying these studies, which had initially made them theoretically attractive to biologists, were gradually eroded. Concern with human evolution ceded its place to interest in physiological mechanisms. Crew and others began to note that the use of biological theory to justify essentially political decisions had serious limitations. Biologists had become uncomfortable with those very arguments which had originally captured their interest. Recognition of the potential political abuse wrought by applying scientific principles to society was expressed by Crew just one year after the Zurich meeting. Referring to previous assessments of the role of sex in reproduction, he generalized: In the past the biologist has justified feudalism, Manchester Liberalism, socialism and every other type of social organization and political programme by reference to selected biological phenomena.⁸⁶ By 1932 Crew had also begun to question the biological logic of regulated breeding, and had made it clear to his American sponsor that there was no simple correspondence between the practice of birth control and the genetic improvement of the human race.⁸⁷ Biologists further began to recognize, however, that although the hopeful genetic solution to human problems was probably an illusion, contraception still remained one tangible means to alleviate, human misery. Some laboratory scientists, like Crew, acknowledged the applicability of their own particular skills to this problem. For a few brief years, social needs and scientific goals were mutually supportive and closely intertwined. But as laboratory researchers gained interest in the study of reproduction and established their own priorities in this field, they temporarily withdrew from the arena of debate over birth control as an important mechanism for social reform.With the rise of Hitler, the genetic arguments for birth control rapidly lost their appeal. But by that time the scientific problem of how to achieve effective contraception had entered the professional consciousness. Both physicians and scientists began to be aware of birth control as a subject within their domain of expertise, although outside the principal focus of their research. Scientific discussion of birth control permanently altered from a question of justification to a problem of method: How could one achieve reliable and safe contraception? This had been Sanger's and Dickinson's goal from the beginning. Laboratory scientists had indeed been persuaded to undertake this work; this research had in turn affected biologists' perceptions of the whole field of reproductive physiology, encouraging further study of reproductive mechanisms. The promise of new knowledge provided for continued funding of this research, despite the caution by scientists that the social benefits would not be as immediate or as far-reaching as advocates and they themselves had first argued.The activities of birth control activists and their supporting agencies, and the financial backing of private contributors and foundations, notably the Rockefeller philanthropies, provided an important new stimulus to the development of research on the biology of reproduction in the late 1920s and early 1930s. Biologists were able to claim an enlarged realm of issues for scientific study through their activities as advocates and as investigators for the birth control movement. At the same time, they promised as-yet-undiscovered possibilities for regulating human reproduction once its physiology was understood. The knowledge and control that they promised lay in understanding the whole reproductive cycle — not merely in evaluating the toxic effects of presumptive spermicides.Chemical spermicides never summoned the interest of scientists as the contraceptive pill was to do, yet that research did reinforce the widespread perceptions of scientific research as essential to social reform. Spermicide investigations focused research efforts in reproductive biology by challenging traditional taboos, defining problems for further study, and providing laboratory investigators the opportunity to assert the social and scientific value of their own skills. Crew echoed this attitude as he observed in 1934:Man has turned from the adventurous conquest of his environment to the conquest of himself. To-day is the day of biological invention, eagerly used for the control of the undesirable and the unwanted. Sex and reproduction are no longer hedged around by myth and taboo; they are no longer accepted as mysteries that defy understanding. They are matters inviting examination and explanation; they are regarded as expressions of physico-chemical forces, the nature of which is to be displayed. It is accepted that when knowledge is sufficient, control will be absolute, and, though knowledge is not yet sufficient, readers ... must be persuaded to the view that this will not always be so.⁸⁸ The synergism between reproductive biology and social needs has been temporary and sporadic, but recurring, since the 1920s. Scientific research programs have clearly been influenced by issues raised by public debate. Nevertheless, reproductive biologists have continued to assert their own professional goals. For the most part, they have rejected problems without inherent scientific interest and have spurned applied research except as it has had a direct bearing on current research themes. This attitude, apparent among American and British investigators in the 1930s, created the intellectual context for the invention and acceptance of the technically sophisticated oral contraceptive pill. It did not foster the production and improvement of the simple, safe, effective, and cheap vaginal contraceptive desired by early birth control advocates.     

Food habits of sika deer in the Shiranuka Hills,eastern Hokkaido: a northern example from the north–south variations in food habits in sika deer

Seasonal changes in the composition of the diet of the sika deer population in the Shiranuka Hills, eastern Hokkaido, in 1998 were determined by fecal analyses. The deer were dependent on Sasa nipponica, a dwarf bamboo, throughout the year, particularly in winter when it accounted for as much as 77.7% of the diet. It accounted for 33.1% and 45.6% in spring and summer, respectively, and this decreased to 12.2% in autumn. Besides S. nipponica, all the graminoid categories accounted for large amounts (66–96.7%), while dicotyledonous plants accounted for little (3–8%) except in autumn when they accounted for 31%. The strong dependence of the Shiranuka population on graminoids was different from other Hokkaido deer populations, for example the population from Ashoro/Onbetsu and the extremely high density population on Nakanoshima Island. In spite of these differences, food for all Hokkaido sika deer was poor in winter. Along the north–south geographical cline in the food composition of sika deer along the Japanese archipelago, the Shiranuka population was positioned as a grazer type, in contrast to the southern populations. However, it is important to note that variations are great among local populations in Hokkaido.     

Variation in the reproductive performance of the Trollius–Chiastocheta mutualism at the edge of its range in north-east Germany

Empirical studies into obligate pollination mutualisms which elucidate the variation in reproductive performance of shrinking populations within human-altered environments are rare. This study focuses on the obligate pollination mutualism between Trollius europaeus (Ranunculaceae) and fly species of the genus Chiastocheta which act both as the plant’s main pollinators and as predators in that their larvae eat a fraction of the developing seeds. The study area is situated in the lowlands of north-east Germany. Many populations of T. europaeus have become comparatively small and scattered in this region as a consequence of agricultural land use intensification. We studied the plant’s reproductive fitness in populations ranging in size from 7 to 12,000 flowers. In a field experiment, we applied four pollination treatments and also recorded fly density in 28 natural T. europaeus populations. The fitness of the offspring from 19 populations was studied in a common garden experiment. In both approaches, a reduction in the fitness of small host plant populations could be demonstrated. Fitness loss can be put down to the quantitative and qualitative limitation of pollen caused by inbreeding and the negative feedback on relative seed set caused by the reduced ability of small plant populations to support a sufficiently large fly population. Although increases in fly density are associated with rising predation costs, the plant species’ net benefit is a positive function of its population size. Our study highlights the reproductive variability of the Trollius–Chiastocheta interaction along a population size gradient in a marginal region of its range, thus contributing to the understanding of the overall variability of this mutualism.     

What we can learn from the dynamics of the 1889 ‘Russian flu’ pandemic for the future trajectory of COVID-19

A study of the contemporary medical literature for patient symptoms from the so-called ‘Russian flu’ pandemic from 1889 revealed clinical observations that resemble COVID-19 (Brüssow and Brüssow, 2021, Microb Biotechnol). If one accepts the hypothesis that this pandemic was a prior coronavirus epidemic, the dynamics of the ‘Russian flu’ from 1889 might give us some ideas about the future trajectory of the COVID-19 pandemic. The present report compiles and reviews the contemporary data published on the temporal and geographical spread of the ‘Russian flu’, its epidemic wave structure and possible later resurgence. The historical record of past pandemics might thus provide us not with predictions, but ‘retrodictions’ on possible future scenarios for the COVID-19 pandemic.     

Hydraulic sorting of microbiota in calciturbidites— A dinantian case study from the rheinische schiefergebirge,Germany

Summary A calciturbidite bed from the lower part of the Kieselkalk Formation (late cd II) at Wallau, eastern Rheinisches Schiefergebirge, displays ideal grading of reworked calcareous shallow-water microbiota, ranging from plurimillimetric agglutinated foraminifers and fragments of calcareous algae (Koninckopora sp.) to plurimicronic calcispheres, radiolarians and sponge spicules. Microbiota derived from all levels of the platform. Correspondingly, several carbonate microfacies types could be discerned. The early diagenetic micrite base of the turbidite preserved the anoxic basinal facies. The turbidite bed belongs to Foraminiferal Zone 15 (V3bα), theAlbaillella cartalla Zone (radiolarian chronology), and is the Lower and part of the Uppertexanus Zone (standard conodont zonation). From the few published data on foraminifers, the Kieselkalk is thought to range from Mid Viséan V2b to Late Viséan V3b gamma.     

Are there seasonal variations of trace element concentrations (Cd,Pb, Zn) in wood of Fagus trees in Germany?

Concentrations of Cd, Pb and Zn were determined in stem wood of beech trees (Fagus sylvatica L.) from 3 sites in northern Germany. Distinct radial distribution patterns of the elements were observed in the xylem. Concentrations of Cd and Pb increased from the youngest, outermost annual rings towards the center of the stem. With Zn intermediate concentrations were observed in the sapwood and higher levels at the center of the stem.Temporal and spatial stability of such distribution patterns in the trunks was investigated. Wood samples taken from the same individual tree in different months of the year were analysed. Marked seasonal variations of mineral concentrations were observed. Also the shape of the distribution patterns of the elements varied with the season. Such variations were larger than those observed with samples taken simultaneously from different sides of the trunk. Furthermore, Pb concentrations in the stem showed variations with height above ground.The results indicate, that radial distribution patterns of Cd, Pb and Zn in xylem rings of beech are not stable. Biomonitoring trace element pollution levels by analysis of beech wood is, thus, questionable. To obtain a reliable historical record of pollution from tree rings, the distribution patterns should be stable over a long period of time. This basic requirement of the dendroanalytical method does not hold for the examined beech. Still, with other tree species and under more favourable conditions the dendroanalytical biomonitoring method may prove valuable.Presented as symposium paper at the V International Congress of Ecology, Yokohama, August 23–30, 1990.     

Life in the Universe Paris,November 19–21, 1979

A conference on Life in the Universe, organized by the Council of Europe, and held in Paris, November 19 to 21, 1979, brought together more than 100 scientists from different fields. The aim of this conference was to promote scientific cooperation in Europe, in conjunction with other countries, in fields related to the problem of Life in the Universe. Our knowledge concerning this problem was reviewed in three different sessions. The first session was devoted to the question of planetary evolution; the second session was devoted to the question of the origin and evolution of life, and the third session was devoted to the problem of evolution of intelligence and the search for extraterrestrial intelligence. The Drake formula was the keynote of the conference. Each session tried to estimate some of the parameters of this formula, in order to examine the question: how many extraterrestrial civilizations with a level of technology at least equal to ours may be present in the universe? Even if no definite answer is given to this question, this meeting pointed out the need for more research.