BACKGROUND: By the middle of the 19th century, leprosy was a serious public health problem in Norway. By 1920, new cases only rarely occurred. This study aims to explain the disappearance of leprosy from Norway. METHODS: Data from the National Leprosy Registry of Norway and population censuses were used. The patient data include year of birth, onset of disease, registration, hospital admission, death, and emigration. The Norwegian data were analysed using epidemiological models of disease transmission and control. RESULTS: The time trend in leprosy new case detection in Norway can be reproduced adequately. The shift in new case detection towards older ages which occurred over time is accounted for by assuming that infected individuals may have a very long incubation period. The decline cannot be explained fully by the Norwegian policy of isolation of patients: an autonomous decrease in transmission, reflecting improvements in for instance living conditions, must also be assumed. The estimated contribution of the isolation policy to the decline in new case detection very much depends on assumptions made on build-up of contagiousness during the incubation period and waning of transmission opportunities due to rapid transmission to close contacts. CONCLUSION: The impact of isolation on interruption of transmission remains uncertain. This uncertainty also applies to contemporary leprosy control that mainly relies on chemotherapy treatment. Further research is needed to establish the impact of leprosy interventions on transmission.
BACKGROUND: By the middle of the 19th century, leprosy was a serious public health problem in Norway. By 1920, new cases only rarely occurred. This study aims to explain the disappearance of leprosy from Norway. METHODS: Data from the National Leprosy Registry of Norway and population censuses were used. The patient data include year of birth, onset of disease, registration, hospital admission, death, and emigration. The Norwegian data were analysed using epidemiological models of disease transmission and control. RESULTS: The time trend in leprosy new case detection in Norway can be reproduced adequately. The shift in new case detection towards older ages which occurred over time is accounted for by assuming that infected individuals may have a very long incubation period. The decline cannot be explained fully by the Norwegian policy of isolation of patients: an autonomous decrease in transmission, reflecting improvements in for instance living conditions, must also be assumed. The estimated contribution of the isolation policy to the decline in new case detection very much depends on assumptions made on build-up of contagiousness during the incubation period and waning of transmission opportunities due to rapid transmission to close contacts. CONCLUSION: The impact of isolation on interruption of transmission remains uncertain. This uncertainty also applies to contemporary leprosy control that mainly relies on chemotherapy treatment. Further research is needed to establish the impact of leprosy interventions on transmission.
Authors: Jéssica da Silva Ferreira; Diego Augusto Souza Oliveira; João Pedro Santos; Carla Carolina Dias Uzedo Ribeiro; Bruna A Baêta; Rafaella Câmara Teixeira; Arthur da Silva Neumann; Patricia Sammarco Rosa; Maria Cristina Vidal Pessolani; Milton Ozório Moraes; Gervásio Henrique Bechara; Pedro L de Oliveira; Marcos Henrique Ferreira Sorgine; Philip Noel Suffys; Amanda Nogueira Brum Fontes; Lesley Bell-Sakyi; Adivaldo H Fonseca; Flavio Alves Lara Journal: PLoS Negl Trop Dis Date: 2018-12-19
Authors: Bogdan Pop; Bogdan Fetica; Mihaiela Luminita Blaga; Adrian Pavel Trifa; Patriciu Achimas-Cadariu; Catalin Ioan Vlad; Andrei Achimas-Cadariu Journal: Med Pharm Rep Date: 2019-01-15
Authors: Arthur da Silva Neumann; Felipe de Almeida Dias; Jéssica da Silva Ferreira; Amanda Nogueira Brum Fontes; Patricia Sammarco Rosa; Rafael Enrique Macedo; José Henrique Oliveira; Raquel Lima de Figueiredo Teixeira; Maria Cristina Vidal Pessolani; Milton Ozório Moraes; Philip Noel Suffys; Pedro L Oliveira; Marcos Henrique Ferreira Sorgine; Flavio Alves Lara Journal: PLoS One Date: 2016-05-20 Impact factor: 3.240