Spanish influenza in Japanese armed forces, 1918-1920

Lost Lessons of the 1918 Influenza: The 1920s Working Hypothesis, the Public Health Paradigm, and the Prevention of Deadly Pandemics

In standard historical accounts, the hyperlethal 1918 flu pandemic was inevitable once a novel influenza virus appeared. However, in the years following the pandemic, it was obvious to distinguished flu experts from around the world that social and environmental conditions interacted with infectious agents and could enhance the virulence of flu germs. On the basis of the timing and geographic pattern of the pandemic, they hypothesized that an "essential cause" of the pandemic's extraordinary lethality was the extreme, prolonged, and industrial-scale overcrowding of US soldiers in World War I, particularly on troopships. This literature synthesis considers research from history, public health, military medicine, veterinary science, molecular genetics, virology, immunology, and epidemiology. Arguments against the hypothesis do not provide disconfirming evidence. Overall, the findings are consistent with an immunologically similar virus varying in virulence in response to war-related conditions. The enhancement-of-virulence hypothesis deserves to be included in the history of the pandemic and the war. These lost lessons of 1918 point to possibilities for blocking the transformation of innocuous infections into deadly disasters and are relevant beyond influenza for diseases like COVID-19. (Am J Public Health. 2022;112(10):1454-1464. https://doi.org/10.2105/AJPH.2022.306976).

The story of critical care in Asia: a narrative review

Background

Asia has more critically ill people than any other part of our planet. The aim of this article is to review the development of critical care as a specialty, critical care societies and education and research, the epidemiology of critical illness as well as epidemics and pandemics, accessibility and cost and quality of critical care, culture and end-of-life care, and future directions for critical care in Asia.

Main body

Although the first Asian intensive care units (ICUs) surfaced in the 1960s and the 1970s and specialisation started in the 1990s, multiple challenges still exist, including the lack of intensivists, critical care nurses, and respiratory therapists in many countries. This is aggravated by the brain drain of skilled ICU staff to high-income countries. Critical care societies have been integral to the development of the discipline and have increasingly contributed to critical care education, although critical care research is only just starting to take off through collaboration across groups. Sepsis, increasingly aggravated by multidrug resistance, contributes to a significant burden of critical illness, while epidemics and pandemics continue to haunt the continent intermittently. In particular, the coronavirus disease 2019 (COVID-19) has highlighted the central role of critical care in pandemic response. Accessibility to critical care is affected by lack of ICU beds and high costs, and quality of critical care is affected by limited capability for investigations and treatment in low- and middle-income countries. Meanwhile, there are clear cultural differences across countries, with considerable variations in end-of-life care. Demand for critical care will rise across the continent due to ageing populations and rising comorbidity burdens. Even as countries respond by increasing critical care capacity, the critical care community must continue to focus on training for ICU healthcare workers, processes anchored on evidence-based medicine, technology guided by feasibility and impact, research applicable to Asian and local settings, and rallying of governments for support for the specialty.

Conclusions

Critical care in Asia has progressed through the years, but multiple challenges remain. These challenges should be addressed through a collaborative approach across disciplines, ICUs, hospitals, societies, governments, and countries.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40560-021-00574-4.

Long-lasting effects of pandemics: The case of the 1918 influenza pandemic in Argentina

The 2019 novel coronavirus disease pandemic poses a serious threat. While its short-term effects are evident, its long-term consequences are a matter of analysis. In this work, the existence of long-lasting negative effects derived from exposure in utero to a great pandemic -1918 influenza pandemic- is analysed for the Argentine case. Outcomes of interest include educational achievement and unemployment status in adulthood -50 years after the pandemic. Based on a regression analysis, temporal differences in the spread of the pandemic and between close birth cohorts are exploited. The results indicate a significant reduction in educational achievement for people exposed in utero to the pandemic. In the region with the highest incidence of cases (Noroeste), this reduction is 0.5 years of education. There are no significant changes in the chances of being unemployed. In the context of climate change, these results constitute a call of attention for the implementation of child protection policies from gestation.

Early-life exposure to weather shocks and child height: Evidence from industrializing Japan

In this study, we estimate the long-run effects of early-life exposure to weather shocks on the height of primary school children. To estimate the global impacts on almost the entire child population in an industrializing country, we utilize both a unique nationwide multi-dimensional longitudinal dataset of Japanese children aged 6-11 and official monthly statistics on meteorological conditions in the 1920s. We observe that the exposure to cold waves in early-life exerted stunting effects on both the boys and girls. In the coldest regions in the northeastern area of Japan, the stunting effects of cold weather shocks on the boys and girls are estimated to be approximately 0.8 and 0.6 cm, respectively. Our observation indicates that prenatal (postnatal) exposure is important for the boys (girls). Our results suggest that the marginal effects of cold waves are stronger in the warmer regions than in the colder regions.

The long-run effects of pandemic influenza on the development of children from elite backgrounds: Evidence from industrializing Japan

This study estimates the lingering effects of fetal exposure to the 1918 influenza pandemic on the development of secondary school and girls' high school students in industrializing Japan. In order to refine the verification of the fetal origins hypothesis, we tried not only to focus on children from elite schools but also to construct the continuous influenza mortality measure using monthly variations in the number of births and influenza deaths. By utilizing a nationwide multidimensional physical examination dataset, we found that fetal exposure to influenza in the pandemic years reduced the heights of boys and girls by approximately 0.3 cm and 0.1 cm, respectively. While the strongest negative magnitude was observed in the pandemic period, the lingering relapses in the post-pandemic period still had considerable adverse effects on height. In relation to the lowest decile group which experienced normal influenza mortality in non-pandemic years, the heights of the boys and girls who experienced pandemic influenza in the womb are approximately 0.6 and 0.3 cm lower. The lingering influenza relapse in the post-pandemic period has an adverse effect on the boys' height, accounting for roughly 80% of the maximum pandemic effect.

Markers of Disease Severity in Patients with Spanish Influenza in the Japanese Armed Forces, 1919-1920

We examined preserved medical charts of 470 Spanish influenza patients (8 with fatal cases) hospitalized at former army hospitals in Japan during 1919–1920. The following factors were associated with longer periods of hospitalization: adventitious discontinuous lung sounds, maximum respiration rate, continuation of high fever after hospital admission, and diphasic fever.

Does in utero exposure to Illness matter? The 1918 influenza epidemic in Taiwan as a natural experiment

This paper tests whether in utero conditions affect long-run developmental outcomes using the 1918 influenza pandemic in Taiwan as a natural experiment. Combining several historical and current datasets, we find that cohorts in utero during the pandemic are shorter as children/adolescents and less educated compared to other birth cohorts. We also find that they are more likely to have serious health problems including kidney disease, circulatory and respiratory problems, and diabetes in old age. Despite possible positive selection on health outcomes due to high infant mortality rates during this period (18%), our paper finds a strong negative impact of in utero exposure to influenza.

Deaths associated with influenza pandemic of 1918-19, Japan

Current estimates of deaths from the influenza pandemic of 1918–19 in Japan are based on vital records and range from 257,000 to 481,000. The resulting crude death rate range of 0.47%–0.88% is considerably lower than parallel and conservative worldwide estimates of 1.66%–2.77%. Because the accuracy of vital registration records for early 20th century Asia is questionable, to calculate the percentage of the population who died from the pandemic, we used alternative prefecture-level population count data for Japan in combination with estimation methods for panel data that were not available to earlier demographers. Our population loss estimates of 1.97–2.02 million are appreciably higher than the standing estimates, and they yield a crude rate of population loss of 3.62%–3.71%. This rate resolves a major puzzle about the pandemic by indicating that the experience of Japan was similar to that of other parts of Asia.

Updated values for molecular diagnosis for highly pathogenic avian influenza virus

Highly pathogenic avian influenza (HPAI) viruses of the H5N1 strain pose a pandemic threat. H5N1 strain virus is extremely lethal and contagious for poultry. Even though mortality is 59% in infected humans, these viruses do not spread efficiently between humans. In 1997, an outbreak of H5N1 strain with human cases occurred in Hong Kong. This event highlighted the need for rapid identification and subtyping of influenza A viruses (IAV), not only to facilitate surveillance of the pandemic potential of avian IAV, but also to improve the control and treatment of infected patients. Molecular diagnosis has played a key role in the detection and typing of IAV in recent years, spurred by rapid advances in technologies for detection and characterization of viral RNAs and proteins. Such technologies, which include immunochromatography, quantitative real-time PCR, super high-speed real-time PCR, and isothermal DNA amplification, are expected to contribute to faster and easier diagnosis and typing of IAV.

Influenza infectious dose may explain the high mortality of the second and third wave of 1918-1919 influenza pandemic

Background

It is widely accepted that the shift in case-fatality rate between waves during the 1918 influenza pandemic was due to a genetic change in the virus. In animal models, the infectious dose of influenza A virus was associated to the severity of disease which lead us to propose a new hypothesis. We propose that the increase in the case-fatality rate can be explained by the dynamics of disease and by a dose-dependent response mediated by the number of simultaneous contacts a susceptible person has with infectious ones.

Methods

We used a compartment model with seasonality, waning of immunity and a Holling type II function, to model simultaneous contacts between a susceptible person and infectious ones. In the model, infected persons having mild or severe illness depend both on the proportion of infectious persons in the population and on the level of simultaneous contacts between a susceptible and infectious persons. We further allowed for a high or low rate of waning immunity and volunteer isolation at different times of the epidemic.

Results

In all scenarios, case-fatality rate was low during the first wave (Spring) due to a decrease in the effective reproduction number. The case-fatality rate in the second wave (Autumn) depended on the ratio between the number of severe cases to the number of mild cases since, for each 1000 mild infections only 4 deaths occurred whereas for 1000 severe infections there were 20 deaths. A third wave (late Winter) was dependent on the rate for waning immunity or on the introduction of new susceptible persons in the community. If a group of persons became voluntarily isolated and returned to the community some days latter, new waves occurred. For a fixed number of infected persons the overall case-fatality rate decreased as the number of waves increased. This is explained by the lower proportion of infectious individuals in each wave that prevented an increase in the number of severe infections and thus of the case-fatality rate.

Conclusion

The increase on the proportion of infectious persons as a proxy for the increase of the infectious dose a susceptible person is exposed, as the epidemic develops, can explain the shift in case-fatality rate between waves during the 1918 influenza pandemic.

A mouse model of lethal synergism between influenza virus and Haemophilus influenzae

Secondary bacterial infections that follow infection with influenza virus result in considerable morbidity and mortality in young children, the elderly, and immunocompromised individuals and may also significantly increase mortality in normal healthy adults during influenza pandemics. We herein describe a mouse model for investigating the interaction between influenza virus and the bacterium Haemophilus influenzae. Sequential infection with sublethal doses of influenza and H. influenzae resulted in synergy between the two pathogens and caused mortality in immunocompetent adult wild-type mice. Lethality was dependent on the interval between administration of the bacteria and virus, and bacterial growth was prolonged in the lungs of dual-infected mice, although influenza virus titers were unaffected. Dual infection induced severe damage to the airway epithelium and confluent pneumonia, similar to that observed in victims of the 1918 global influenza pandemic. Increased bronchial epithelial cell death was observed as early as 1 day after bacterial inoculation in the dual-infected mice. Studies using knockout mice indicated that lethality occurs via a mechanism that is not dependent on Fas, CCR2, CXCR3, interleukin-6, tumor necrosis factor, or Toll-like receptor-4 and does not require T or B cells. This model suggests that infection with virulent strains of influenza may predispose even immunocompetent individuals to severe illness on secondary infection with H. influenzae by a mechanism that involves innate immunity, but does not require tumor necrosis factor, interleukin-6, or signaling via Toll-like receptor-4.

Nurses' contacts and potential for infectious disease transmission

These data can help predict staff availability and provide information for pandemic preparedness planning.

Nurses’ contacts with potentially infectious persons probably place them at higher risk than the general population for infectious diseases. During an influenza pandemic, illness among nurses might result in staff shortage. We aimed to show the value of individual data from the healthcare sector for mathematical modeling of infectious disease transmission. Using a paper diary approach, we compared nurses’ daily contacts (2-way conversation with >2 words or skin-to-skin contact) with those of matched controls from a representative population survey. Nurses (n = 129) reported a median of 40 contacts (85% work related), and controls (n = 129) reported 12 contacts (33% work related). For nurses, 51% of work-related contacts were with patients (74% involving skin-to-skin contact, and 63% lasted <15 minutes); 40% were with staff members (29% and 36%, respectively). Our data, used with simulation models, can help predict staff availability and provide information for pandemic preparedness planning.

A comparative study of the 1918-1920 influenza pandemic in Japan, USA and UK: mortality impact and implications for pandemic planning

Historical studies of influenza pandemics can provide insight into transmission and mortality patterns, and may aid in planning for a future pandemic. Here, we analyse historical vital statistics and quantify the age-specific mortality patterns associated with the 1918-1920 influenza pandemic in Japan, USA, and UK. All three countries showed highly elevated mortality risk in young adults relative to surrounding non-pandemic years. By contrast, the risk of death was low in the very young and very old. In Japan, the overall mortality impact was not limited to winter 1918-1919, and continued during winter 1919-1920. Mortality impact varied as much as threefold across the 47 Japanese prefectures, and differences in baseline mortality, population demographics, and density explained a small fraction of these variations. Our study highlights important geographical variations in timing and mortality impact of historical pandemics, in particular between the Eastern and Western hemispheres. In a future pandemic, vaccination in one region could save lives even months after the emergence of a pandemic virus in another region.

Nonpharmaceutical Interventions for Military Populations During Pandemic Influenza

Influenza causes substantial illness and loss of work days among young adults, and outbreaks can affect the preparedness of military units. In an influenza pandemic, people who live in confined settings have greater risk of infection. Military trainees are at particularly high risk. Because of likely unavailability of vaccines and antiviral drugs at the start of a pandemic and for many months thereafter, nonpharmaceutical interventions may be very important. During a pandemic, it seems prudent that military public health officials employ at least several nonpharmaceutical interventions. For example frequent handwashing and respiratory hygiene/cough etiquette should be strongly encouraged among soldiers. Head-to-toe sleeping, a "no-cost" intervention should be for crowded berthing areas. Isolation of patients with influenza and quarantine of their close contacts should be employed. Masks and alcohol-based hand rubs may be employed among those at highest risk. Finally, whenever possible military planners should, reduce crowding and limit the interaction of training cohorts to reduce risk of influenza virus transmission.