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Pasha O, Luby SP, Khan AJ, Shah SA, McCormick JB, Fisher-Hoch SP.Pasha O, et al.Epidemiol Infect. 1999 Dec;123(3):515-8. doi: 10.1017/s0950268899002770.Epidemiol Infect. 1999.PMID: 10694166Free PMC article.