Serotype-Specific Transmission and Waning Immunity of Endemic Foot-and-Mouth Disease Virus in Cameroon.
Foot-and-mouth disease virus (FMDV) causes morbidity and mortality in a range of animals and threatens local economies by acting as a barrier to international trade. The outbreak in the United Kingdom in 2001 that cost billions to control highlighted the risk that the pathogen poses to agriculture. In response, several mathematical models have been developed to parameterize and predict both transmission dynamics and optimal disease control. However, a lack of understanding of the multi-strain etiology prevents characterization of multi-strain dynamics. Here, we use data from FMDV serology in an endemic setting to probe strain-specific transmission and immunodynamics. Five serotypes of FMDV affect cattle in the Far North Region of Cameroon. We fit both catalytic and reverse catalytic models to serological data to estimate the force of infection and the rate of waning immunity, and to detect periods of sustained transmission. For serotypes SAT2, SAT3, and type A, a model assuming life-long immunity fit better. For serotypes SAT1 and type O, the better-fit model suggests that immunity may wane over time. Our analysis further indicates that type O has the greatest force of infection and the longest duration of immunity. Estimates for the force of infection were time-varying and indicated that serotypes SAT1 and O displayed endemic dynamics, serotype A displayed epidemic dynamics, and SAT2 and SAT3 did not sustain local chains of transmission. Since these results were obtained from the same population at the same time, they highlight important differences in transmission specific to each serotype. They also show that immunity wanes at rates specific to each serotype, which influences patterns of local persistence. Overall, this work shows that viral serotypes can differ significantly in their epidemiological and immunological characteristics. Patterns and processes that drive transmission in endemic settings must consider complex viral dynamics for accurate representation and interpretation.
Department of Veterinary Preventive Medicine, Ohio State University, Columbus, OH, United States of America.
Laura W
LW
Pomeroy
Department of Biology, Pennsylvania State University, University Park, PA, United States of America; Department of Entomology, Pennsylvania State University, University Park, PA, United States of America; Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America; Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America.
Ottar N
ON
Bjørnstad
Department of Geography, Ohio State University, Columbus, OH, United States of America.
Hyeyoung
H
Kim
Laboratoire National Veterinaire, Lanavet, Garoua, Cameroon.
Simon Dickmu
SD
Jumbo
Laboratoire National Veterinaire, Lanavet, Garoua, Cameroon.
Souley
S
Abdoulkadiri
Department of Veterinary Preventive Medicine, Ohio State University, Columbus, OH, United States of America; Public Health Preparedness for Infectious Disease Program, The Ohio State University, Columbus, OH, United States of America.
Rebecca
R
Garabed
D000822:Animal Husbandry / Q000379:methods; D000818:Animals; D002163:Cameroon / Q000453:epidemiology; D002417:Cattle / Q000276:immunology / Q000821:virology; D002418:Cattle Diseases / Q000453:epidemiology / Q000276:immunology / Q000635:transmission* / Q000821:virology; D058872:Epidemics / Q000662:veterinary; D005536:Foot-and-Mouth Disease / Q000453:epidemiology / Q000276:immunology / Q000635:transmission* / Q000821:virology; D029544:Foot-and-Mouth Disease Virus / Q000276:immunology*; D015233:Models, Statistical; D065288:Serogroup