N J Gay1. 1. Immunisation Division, PHLS Communicable Disease Surveillance Centre, London, UK.
Abstract
BACKGROUND: The epidemiology of hepatitis A in countries across the world is changing due to improvements in hygiene and living conditions which reduce the transmissibility of the infection. METHODS: A mathematical model is formulated to describe the changes in incidence of a directly transmitted infection produced by a long term decline in its transmissibility. The basic reproduction number, the parameter describing transmissibility, is considered as a function of time. The relationship between the basic reproduction number and the force of infection is derived. RESULTS: Theoretical examples demonstrate that a decline in transmissibility results in an initial decline in the force of infection, but that this may be followed by a substantial resurgence. Resurgences may be possible after several decades of declining incidence, and are most marked following a rapid decline. CONCLUSIONS: Countries which have experienced a rapid decline in the incidence of hepatitis A may be at risk of a resurgence. More detailed mathematical models, informed with data from regular age-stratified serological surveys, should provide the basis for decisions on vaccination policy.
BACKGROUND: The epidemiology of hepatitis A in countries across the world is changing due to improvements in hygiene and living conditions which reduce the transmissibility of the infection. METHODS: A mathematical model is formulated to describe the changes in incidence of a directly transmitted infection produced by a long term decline in its transmissibility. The basic reproduction number, the parameter describing transmissibility, is considered as a function of time. The relationship between the basic reproduction number and the force of infection is derived. RESULTS: Theoretical examples demonstrate that a decline in transmissibility results in an initial decline in the force of infection, but that this may be followed by a substantial resurgence. Resurgences may be possible after several decades of declining incidence, and are most marked following a rapid decline. CONCLUSIONS: Countries which have experienced a rapid decline in the incidence of hepatitis A may be at risk of a resurgence. More detailed mathematical models, informed with data from regular age-stratified serological surveys, should provide the basis for decisions on vaccination policy.
Authors: A M Naser; M J Hossain; H M S Sazzad; N Homaira; E S Gurley; G Podder; S Afroj; S Banu; P E Rollin; P Daszak; B-N Ahmed; M Rahman; S P Luby Journal: Epidemiol Infect Date: 2014-10-24 Impact factor: 2.451
Authors: Kim M Pepin; Shannon L Kay; Ben D Golas; Susan S Shriner; Amy T Gilbert; Ryan S Miller; Andrea L Graham; Steven Riley; Paul C Cross; Michael D Samuel; Mevin B Hooten; Jennifer A Hoeting; James O Lloyd-Smith; Colleen T Webb; Michael G Buhnerkempe Journal: Ecol Lett Date: 2017-01-16 Impact factor: 9.492