Question: When did the y. pestis reach the country of citizenship of the author of Birthday Letters?

<P0-S0> St Botolph's Review was the student-made poetry journal from Cambridge University, England in 1956, which saw the first publication of Ted Hughes' poetry, at the launch of which Hughes met Sylvia Plath. <P0-S1> The first issue appeared on 26 February 1956. <SEP> <P1-S0> the dominant explanation for the black death is the plague theory, which attributes the outbreak to yersinia pestis, also responsible for an epidemic that began in southern china in 1865, eventually spreading to india. <P1-S1> the investigation of the pathogen that caused the 19th-century plague was begun by teams of scientists who visited hong kong in 1894, among whom was the french-swiss bacteriologist alexandre yersin, after whom the pathogen was named yersinia pestis. <P1-S2> the mechanism by which y. pestis was usually transmitted was established in 1898 by paul-louis simond and was found to involve the bites of fleas whose midguts had become obstructed by replicating y. pestis several days after feeding on an infected host. <P1-S3> this blockage results in starvation and aggressive feeding behaviour by the fleas, which repeatedly attempt to clear their blockage by regurgitation, resulting in thousands of plague bacteria being flushed into the feeding site, infecting the host. <P1-S4> the bubonic plague mechanism was also dependent on two populations of rodents: one resistant to the disease, which act as hosts, keeping the disease endemic, and a second that lack resistance. <P1-S5> when the second population dies, the fleas move on to other hosts, including people, thus creating a human epidemic. <SEP> <P2-S0> The study also found that there were two previously unknown but related clades (genetic branches) of the Y. pestis genome associated with medieval mass graves. <P2-S1> These clades (which are thought to be extinct) were found to be ancestral to modern isolates of the modern Y. pestis strains Y. p. orientalis and Y. p. medievalis, suggesting the plague may have entered Europe in two waves. <P2-S2> Surveys of plague pit remains in France and England indicate the first variant entered Europe through the port of Marseille around November 1347 and spread through France over the next two years, eventually reaching England in the spring of 1349, where it spread through the country in three epidemics. <P2-S3> Surveys of plague pit remains from the Dutch town of Bergen op Zoom showed the Y. pestis genotype responsible for the pandemic that spread through the Low Countries from 1350 differed from that found in Britain and France, implying Bergen op Zoom (and possibly other parts of the southern Netherlands) was not directly infected from England or France in 1349 and suggesting a second wave of plague, different from those in Britain and France, may have been carried to the Low Countries from Norway, the Hanseatic cities or another site. <SEP> <P3-S0> the letters patent, 1947 (more formally, the letters patent constituting the office of governor general and commander-in-chief of canada) are a legal instrument introduced by king george vi, which came into effect on 1 october 1947 and continue to, along with parts of the "constitution act, 1867", constitute the office of the governor general. <P3-S1> these letters served to expand the role and powers of the governor general in exercising the royal prerogative and allows the governor general to carry out an increased number of the sovereign's duties in "exceptional circumstances". <P3-S2> while the letters patent allow the governor general to use most of the "powers and authorities" lawfully belonging to the canadian sovereign, this permission can be revoked, altered, or amended by the sovereign at any time and these powers and authorities thus remain with the monarch and are carried out by the governor general on his or her behalf. <SEP> <P4-S0> Birthday Letters, published in 1998, is a collection of poetry by English poet and children's writer Ted Hughes. <P4-S1> Released only months before Hughes's death, the collection won multiple prestigious literary awards. <P4-S2> This collection of eighty-eight poems is widely considered to be Hughes's most explicit response to the suicide of his estranged wife Sylvia Plath in 1963, and to their widely discussed, politicized and "explosive" marriage.