Epidemiological impact of vaccination on the dynamics of two childhood diseases in rural Senegal.
Measles and pertussis are ubiquitous vaccine-preventable diseases, which remain an important public health problem in developing countries. Hence, developing a deep understanding of their transmission dynamics remains imperative. To achieve this, we compared the impact of vaccination at both individual and population levels in a Senegalese rural community. This study represents the first such comparative study in tropical conditions and constitutes a point of comparison with other studies of disease dynamics in developed countries. Changes in the transmission rates of infections are reflected in their mean ages at infection and basic reproductive ratio calculated before and after vaccination. We explored persistence of both infections in relation to population size in each village and found the inter-epidemic period for the whole area using wavelets analysis. As predicted by epidemiological theory, we observed an increase in the mean age at infection and a decrease in the reproductive ratio of both diseases. We showed for both the pre- vaccination and vaccine eras that persistence depends on population size. After vaccination, persistence decreased and the inter-epidemic period increased. The observed changes suggest that vaccination against measles and pertussis induced a drop in their transmission. Similarities in disease dynamics to those of temperate regions such as England and Wales were also observed.
Broutin
Hélène
H
UR 024, Institut de Recherche pour le Développement (IRD), 911, Avenue Agropolis BP 64501, 34394 Montpellier cedex 5, France. broutin@mpl.ird.fr
Mantilla-Beniers
Natalia B
NB
Simondon
François
F
Aaby
Peter
P
Grenfell
Bryan T
BT
Guégan
Jean-François
JF
Rohani
Pejman
P
D000293:Adolescent; D001886:Bordetella pertussis / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks / Q000517:prevention & control*; D006801:Humans; D015994:Incidence; D007223:Infant; D008457:Measles / Q000453:epidemiology* / Q000517:prevention & control; D008458:Measles Vaccine / Q000008:administration & dosage*; D008459:Measles virus / Q000276:immunology; D010567:Pertussis Vaccine / Q000008:administration & dosage*; D011156:Population Density; D012424:Rural Population; D012675:Senegal / Q000453:epidemiology; D014611:Vaccination; D014917:Whooping Cough / Q000453:epidemiology* / Q000517:prevention & control
D008458:Measles Vaccine; D010567:Pertussis Vaccine