An epidemic of influenza on Tristan da Cunha

Mantle, John; Tyrrell, D. A. J.

doi:10.1017/s0022172400046246

Cited by 22 publications

(41 citation statements)

References 6 publications

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“…An attack‐rate of 96% was seen on the isolated island of Tristan da Cunha when the H3N2 virus first arrived in 1971, although only 1% died; the population had not been exposed to any form of influenza for 8 or 9 years 34,35 …”

Section: Pandemic Influenza Is Influenced By Age and Isolationmentioning

confidence: 99%

Understanding influenza transmission, immunity and pandemic threats

Mathews

Chesson

McCaw

et al. 2009

Influenza Resp Viruses

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The current pandemic threat can be best understood within an ecological framework that takes account of the history of past pandemics caused by influenza A, the relationships between pandemic and seasonal spread of influenza viruses, and the importance of immunity and behavioural responses in human populations. Isolated populations without recent exposure to seasonal influenza seem more susceptible to new pandemic viruses, and much collateral evidence suggests that this is due to immunity directed against epitopes shared between pandemic and previously circulating strains of inter‐pandemic influenza A virus. In the highly connected modern world, most populations are regularly exposed to non‐pandemic viruses, which can even boost immunity without causing influenza symptoms. Such naturally‐induced immunity helps to explain the low attack‐rates of seasonal influenza, as well as the moderate attack‐rates in many urbanized populations affected by 1918–1919 and later pandemics. The effectiveness of immunity, even against seasonal influenza, diminishes over time because of antigenic drift in circulating viruses and waning of post‐exposure immune responses. Epidemiological evidence suggests that cross‐protection against a new pandemic strain could fade even faster. Nevertheless, partial protection, even of short duration, induced by prior seasonal influenza or vaccination against it, could provide important protection in the early stages of a new pandemic.

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Section: Pandemic Influenza Is Influenced By Age and Isolationmentioning

confidence: 99%

Understanding influenza transmission, immunity and pandemic threats

Mathews

Chesson

McCaw

et al. 2009

Influenza Resp Viruses

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show abstract

“…In the Tristan da Cunha isolate, for example, there is a 45% prevalence of atopy and a 36% prevalence of asthma (Mantle and Tyrrell, 1973; Zamel et al, 1996; Camacho et al, 2011; Camacho and Cazelles, 2013). By comparison, the prevalence of asthma in most out-bred populations rarely exceeds 10%.…”

Section: Introductionmentioning

confidence: 99%

“…By comparison, the prevalence of asthma in most out-bred populations rarely exceeds 10%. The severity of the Tristan da Cunha atopy phenotype may be reflected in events such as the Tristan da Cunha influenza epidemic of 1971 (Mantle and Tyrrell, 1973; Zamel et al, 1996; Camacho et al, 2011; Camacho and Cazelles, 2013). …”

Section: Introductionmentioning

confidence: 99%

Cysteinyl Leukotrienes Pathway Genes, Atopic Asthma and Drug Response: From Population Isolates to Large Genome-Wide Association Studies

et al. 2016

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Genetic variants associated with asthma pathogenesis and altered response to drug therapy are discussed. Many studies implicate polymorphisms in genes encoding the enzymes responsible for leukotriene synthesis and intracellular signaling through activation of seven transmembrane domain receptors, such as the cysteinyl leukotriene 1 (CYSLTR1) and 2 (CYSLTR2) receptors. The leukotrienes are polyunsaturated lipoxygenated eicosatetraenoic acids that exhibit a wide range of pharmacological and physiological actions. Of the three enzymes involved in the formation of the leukotrienes, arachidonate 5 lipoxygenase 5 (ALOX5), leukotriene C4 synthase (LTC4S), and leukotriene hydrolase (LTA4H) are all polymorphic. These polymorphisms often result in variable production of the CysLTs (LTC4, LTD4, and LTE4) and LTB4. Variable number tandem repeat sequences located in the Sp1-binding motif within the promotor region of the ALOX5 gene are associated with leukotriene burden and bronchoconstriction independent of asthma risk. A 444A > C SNP polymorphism in the LTC4S gene, encoding an enzyme required for the formation of a glutathione adduct at the C-6 position of the arachidonic acid backbone, is associated with severe asthma and altered response to the CYSLTR1 receptor antagonist zafirlukast. Genetic variability in the CysLT pathway may contribute additively or synergistically to altered drug responses. The 601 A > G variant of the CYSLTR2 gene, encoding the Met201Val CYSLTR2 receptor variant, is associated with atopic asthma in the general European population, where it is present at a frequency of ∼2.6%. The variant was originally found in the founder population of Tristan da Cunha, a remote island in the South Atlantic, in which the prevalence of atopy is approximately 45% and the prevalence of asthma is 36%. In vitro work showed that the atopy-associated Met201Val variant was inactivating with respect to ligand binding, Ca2+ flux and inositol phosphate generation. In addition, the CYSLTR1 gene, located at Xq13-21.1, has been associated with atopic asthma. The activating Gly300Ser CYSLTR1 variant is discussed. In addition to genetic loci, risk for asthma may be influenced by environmental factors such as smoking. The contribution of CysLT pathway gene sequence variants to atopic asthma is discussed in the context of other genes and environmental influences known to influence asthma.

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“…Biologically-based models for pandemic influenza [1] that incorporate effects of host immunity can help to explain such differences in observed attack rates. Such models could also explain recurrent waves of infection reported from 1918–19 [2]–[4] and 1968–71[6]. Higher attack rates in isolated populations are most likely due to fewer past exposures and lesser immune protection, leading to greater susceptibility.…”

Section: Introductionmentioning

confidence: 99%

A Biological Model for Influenza Transmission: Pandemic Planning Implications of Asymptomatic Infection and Immunity

et al. 2007

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BackgroundThe clinical attack rate of influenza is influenced by prior immunity and mixing patterns in the host population, and also by the proportion of infections that are asymptomatic. This complexity makes it difficult to directly estimate R0 from the attack rate, contributing to uncertainty in epidemiological models to guide pandemic planning. We have modelled multiple wave outbreaks of influenza from different populations to allow for changing immunity and asymptomatic infection and to make inferences about R0.Data and MethodsOn the island of Tristan da Cunha (TdC), 96% of residents reported illness during an H3N2 outbreak in 1971, compared with only 25% of RAF personnel in military camps during the 1918 H1N1 pandemic. Monte Carlo Markov Chain (MCMC) methods were used to estimate model parameter distributions.FindingsWe estimated that most islanders on TdC were non-immune (susceptible) before the first wave, and that almost all exposures of susceptible persons caused symptoms. The median R0 of 6.4 (95% credibility interval 3.7–10.7) implied that most islanders were exposed twice, although only a minority became ill in the second wave because of temporary protection following the first wave. In contrast, only 51% of RAF personnel were susceptible before the first wave, and only 38% of exposed susceptibles reported symptoms. R0 in this population was also lower [2.9 (2.3–4.3)], suggesting reduced viral transmission in a partially immune population.InterpretationOur model implies that the RAF population was partially protected before the summer pandemic wave of 1918, arguably because of prior exposure to interpandemic influenza. Without such protection, each symptomatic case of influenza would transmit to between 2 and 10 new cases, with incidence initially doubling every 1–2 days. Containment of a novel virus could be more difficult than hitherto supposed.

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An epidemic of influenza on Tristan da Cunha

Cited by 22 publications

References 6 publications

Understanding influenza transmission, immunity and pandemic threats

Understanding influenza transmission, immunity and pandemic threats

Cysteinyl Leukotrienes Pathway Genes, Atopic Asthma and Drug Response: From Population Isolates to Large Genome-Wide Association Studies

A Biological Model for Influenza Transmission: Pandemic Planning Implications of Asymptomatic Infection and Immunity

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