The emergence of a suburban penalty during the 1918/19 influenza pandemic in Malta: The role of a marketplace, railway, and measles.

The Malta 1918/19 influenza experience adds to our understanding of the pandemic by illustrating the importance of suburban populations, their vulnerabilities, and elevated mortality rates. Studies on the socio-geographical variation in the 1918/19 influenza mortality has largely overlooked the suburban experience, and thus the often-hidden heterogeneity of the disease experience is missing. A comparison of mortality rates across the three settlement types (urban, suburban, and rural) for the second wave of the pandemic revealed that there were significant differences across the settlement types (x2 = 22.67, 2df, p <0.0001). There was a statistically significant divide between suburban settlement type versus urban and rural communities. Further, the geographical division of the central suburban region had the highest mortality rate at 4.28 per 1000 living of all suburban regions. A closer examination of the central suburban communities revealed that the town of Birchicara was the driving force behind the elevated influenza mortality, with a rate of 5.28 per 1000 living. The exceedingly high rate of influenza mortality in Birchicara was significantly different from the other suburban communities (Z = 2.915, p = 0.004). Birchicara was notable as both a transmission and burden hotspot for influenza infection because of a unique conflation of factors not observed elsewhere on the island. Foremost, was the pitkali market, which was a produce wholesale distributing centre; second, was the fact that the train station was a central hub especially for Maltese labourers; third, was that the measles epidemic in 1916/17 contributed to elevated childhood influenza deaths because the presence of military personnel and their families. We argue that the interaction of the three factors, and in particular, the measles epidemic with childhood influenza, amounted to a syndemic. Factors associated with urbanization and high rates of infectious diseases, such as overcrowding and infant mortality, did not play a primary role in the syndemic.

Assessing a syndemic: Gibraltar in the time of cholera.

More than a decade ago Singer (2009) described Gibraltar's experience with cholera and smallpox in 1865 as a syndemic. In this study, we provide a reassessment of that event and, consequently, propose a methodology to identify a syndemic at the population level. We propose that the concept of the harvesting effect from demographic studies on crisis mortality provides a useful framework for evaluating the presence of a syndemic. Our research begins by establishing a normative baseline mortality (BM) through life table analysis, where changes in life expectancy (LE) around BM can be used to show a distinctive pattern of significant decline and increase. Such was the case with the presence of both cholera and smallpox in the fall of 1865, when LE fell significantly to 19.64 years from the background LE of 32.88 years. A year later, this decline was followed by a significant increase in LE to 41.34 years. Excessive mortality followed by a fallow (healthy) period represents a signature feature of a syndemic driven by a short-term infectious disease epidemic. The presence of both cholera and smallpox in 1860 did not produce similar results, evidence which suggests that the presence of two infectious epidemics in an impoverished population was not sufficient to produce a syndemic. The presence of a protracted state of quarantine, with its concomitant social and economic consequences, was a driving force responsible for amplifying the disease burden in 1865, and elevating to a syndemic status. Multivariate Poisson regression revealed patio level limiting factors (such as, presence of a cistern, a well, a live-in servant, and a Jewish co-resident), as well as risk factors (such as, a smallpox death in the building; the presence of a foreign-born individual). From the two-phase assessment of the syndemic in Gibraltar, we developed a conceptual framework for identifying, contributing, driving, and limiting factors.

Insights into secular trends of respiratory tuberculosis: The 20th century Maltese experience.

Over half a century ago, McKeown and colleagues proposed that economics was a major contributor to the decline of infectious diseases, including respiratory tuberculosis, during the 19th and 20th centuries. Since then, there is no consensus among researchers as to the factors responsible for the mortality decline. Using the case study of the islands of Malta and Gozo, we examine the relationship of economics, in particular, the cost of living (Fisher index) and its relationship to the secular trends of tuberculosis mortality. Notwithstanding the criticism that has been directed at McKeown, we present results that improvement in economics is the most parsimonious explanation for the decline of tuberculosis mortality. We reaffirmed that the reproductively aged individuals were most at risk of dying of tuberculosis, seeing that 70 to 90% of all deaths due to tuberculosis occurred between the ages of 15 and 45. There was a clear sex differential in deaths in that, prior to 1930, rates in females were generally higher than males. During times of extreme hardship, the sex differential was exacerbated. Over the course of World War I, the sex gap in tuberculosis rates increased until peaking in 1918 when there was also the influenza pandemic. The heightened differential was most likely a result of gendered roles as opposed to biological differences since female tuberculosis rates again surpassed male rates in 1945 during World War II. Respiratory tuberculosis in both urban and rural settlements (in Malta proper) was significantly influenced by the Fisher index, which explains approximately 61% of the variation in TB death rates (R = 0.78; p<0.0001). In Gozo, there was no significant impact on respiratory tuberculosis (R = 0.23; p = 0.25), most likely a consequence of the island's isolation, a self-sufficient economy and limited exposure to tuberculosis.

Situating mortality: quantifying crisis points and periods of stability.

A wide range of stressors can cause a dramatic and sudden rise in the death rate in populations, typically resulting in what is referred to as crisis mortality. Here we present a method to standardize the assessment of identifying moments of crises. A modification of the mortality Z-score methodology which is combined with time series analysis was used to investigate mortality events over the course of nearly two centuries for two populations: Gibraltar and Malta. A benefit of this method is that it situates the yearly death rate within the prevailing mortality pattern, and by doing so allows the researcher to assess the relative impact of that event against the norm for the period under investigation. A series of threshold values were established to develop levels of mortality to distinguish moments of lower mortality than expected, background mortality, a crisis, and a catastrophe. Our findings suggested that within defined periods, a limited number of events constituted moments of excessive mortality in the range of a crisis or higher. These included epidemics (yellow fever and influenza in Gibraltar only, and cholera) and casualties associated with World War II. Episodes of lower than expected mortality were only detected (although not significant) in the 20th century in Malta, and at the micro level, the harvesting effect appears to have occurred following cholera epidemics in both locations and influenza in Gibraltar. The analysis demonstrates clearly that the impact of epidemics can be highly variable across time and populations.

The Jewish advantage and household security: life expectancy among 19th Century Sephardim of Gibraltar.

Using the historical population of Gibraltar to examine the pattern of mortality of Jews and Roman Catholics revealed that: (1) the Jews exhibited a significantly better health status as measured by life expectancy at birth (47.66 and 47.56 for Jewish males and females vs. 38.10 and 40.89 for Catholics males and females, respectively), (2) most of the disparity is found in the very young age categories and (3) the significantly lower rates of deaths could be attributed to the diarrheal and nutritional complex. Stage two of the research involved the linkage of deaths over a 7-year period relative to their household context as of 1878. Being Jewish, having a servant, having access to a water well in the tenement and residing in a tenement only with other Jews, were all factors that contributed to a higher life expectancy. Our explanation for the enhanced survivorship among the Jews is grounded in economics as well as in an established welfare system, in religious precepts and in secular knowledge of health. One of the more notable and hitherto unobserved findings is that Roman Catholics residing in the same tenements with Jews enjoyed a distinct health advantage. This suggests that a positive amplification effect arose from their co-residence with the Jews.

Infant and juvenile growth in ancestral Pueblo Indians.

The present study examines patterns of infant and juvenile growth in a diachronic sample of ancestral Pueblo Indians (AD 1300-1680) from the American Southwest. An assessment of growth patterns is accompanied by an evaluation of pathological conditions often considered to be indicators of nutritional deficiencies and/or gastrointestinal infections. Growth patterns and the distribution of pathological conditions are interpreted relative to culturally relevant age categories defined by Puebloan rites of passage described in the ethnographic literature. A visual comparison of growth distance curves revealed that relative to a modern comparative group our sample of ancestral Pueblo infant and juveniles exhibited faltering growth beginning soon after birth to about 5 years of age. A comparison of curves describing growth relative to adult femoral length, however, indicated reduced growth occurring later, by around 2 years of age. Similar to previous studies, we observed a high proportion of nonsurvivors exhibiting porotic cranial lesions during the first 2 years of life. Contrary to expectations, infants and juveniles without evidence of porotic cranial lesions exhibited a higher degree of stunting. Our study is generally consistent with previous research reporting poor health and high mortality for ancestral Pueblo Indian infants and juveniles. Through use of a culturally relevant context defining childhood, we argue that the observed poor health and high mortality in our sample occur before the important transition from young to older child and the concomitant initial incorporation into tribal ritual organization.