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

Abstract

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.

Hot and Cold Spot Areas of Household Tuberculosis Transmission in Southern China: Effects of Socio-Economic Status and Mycobacterium tuberculosis Genotypes

“…The association between TB and socio-economic status has been well documented [27,28,29,30,31,32]. The hot spot areas were predominated by those individuals with low socioeconomic status, which we first believed to be the explanation for Mtb transmission.…”

The 1918 influenza pandemic did not accelerate tuberculosis mortality decline in early‐20th century Newfoundland: Investigating historical and social explanations

“…Analyses of mortality in other locations in the West, including Switzerland (Holloway et al, 2013), Germany (Loddenkemper & Konietzko, 2018), Austria (Wolf & Junker, 2018), the United Kingdom (Davies & Trafford, 2018), and the Netherlands (van Cleef et al, 2018), show a similar decrease in TB mortality. There are a few locations in which mortality did not experience such a decrease, including Malta (Tripp & Sawchuk, 2017), Japan (Mori & Ishikawa, 2018), and South Africa (Beyers & Gie, 2018). Noymer (2011) argued that the lack of acknowledgment of the role of the 1918 influenza pandemic in accelerating the decline of TB mortality is an oversight that must be corrected.…”

Nicotinamide and Demographic and Disease transitions: Moderation is Best

“…Tuberculosis rarely evolves to evade the immune system (unlike the ‘arms races’ of pathogens): hosts may be tolerant for good metabolic reasons but seem perfectly capable of sterilising granulomas when they choose. 227–237 The role of nutrition in activating latent TB has long been implicated and the harvest of deaths from TB when under dietary and other stresses often noted.…”