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Serotype-Specific Transmission and Waning Immunity of Endemic Foot-and-Mouth Disease Virus in Cameroon.

Pomeroy LW, Bjørnstad ON, Kim H, Jumbo SD, Abdoulkadiri S, Garabed R - PLoS ONE (2015)

Bottom Line: For serotypes SAT2, SAT3, and type A, a model assuming life-long immunity fit better.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Veterinary Preventive Medicine, Ohio State University, Columbus, OH, United States of America.

ABSTRACT
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.

No MeSH data available.


Related in: MedlinePlus

Model selection and parameterization results for five FMDV serotypes.Best-fit model results using the catalytic model (for SAT2, SAT3, and type A) or reverse catalytic mode (for SAT1 and type O) with values for the duration of immunity and serotype-specific time-varying forces of infection estimated from serology data.
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pone.0136642.g003: Model selection and parameterization results for five FMDV serotypes.Best-fit model results using the catalytic model (for SAT2, SAT3, and type A) or reverse catalytic mode (for SAT1 and type O) with values for the duration of immunity and serotype-specific time-varying forces of infection estimated from serology data.

Mentions: To quantify the force of infection, we fit the entire dataset for SAT1 and type O to reverse catalytic models and data for SAT2, SAT3, and A to catalytic models, all of which quantified the time-variation in the force of infection using a b-spline. Since local minima and maxima in the force of infection did not occur at the same ages across serotypes, we infer that the force of infection is time-varying. Between 1996 and 2010, estimates for the FOI for SAT1 decrease through time while estimates for the FOI for SAT2 and SAT3 increase through time (Fig 2). Type O shows cyclic variation in the estimated FOI though time, and type A shows two distinct peaks of estimated FOI: one between 2000 and 2002 and the other between 2008 and 2010. Simulations using the better-fit version of the catalytic model with estimated values for the duration of seropositivity after natural infection and serotype-specific time-varying FOI produced a good fit with the data (Fig 3). The mean estimated FOI ranged from the maximum of 0.69 per year for type O to a minimum of 0.021 per year for SAT 2 (Table 3). Therefore, there are clear serotype specific differences in the FOI with regards to magnitude and temporal patterns.


Serotype-Specific Transmission and Waning Immunity of Endemic Foot-and-Mouth Disease Virus in Cameroon.

Pomeroy LW, Bjørnstad ON, Kim H, Jumbo SD, Abdoulkadiri S, Garabed R - PLoS ONE (2015)

Model selection and parameterization results for five FMDV serotypes.Best-fit model results using the catalytic model (for SAT2, SAT3, and type A) or reverse catalytic mode (for SAT1 and type O) with values for the duration of immunity and serotype-specific time-varying forces of infection estimated from serology data.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4556668&req=5

pone.0136642.g003: Model selection and parameterization results for five FMDV serotypes.Best-fit model results using the catalytic model (for SAT2, SAT3, and type A) or reverse catalytic mode (for SAT1 and type O) with values for the duration of immunity and serotype-specific time-varying forces of infection estimated from serology data.
Mentions: To quantify the force of infection, we fit the entire dataset for SAT1 and type O to reverse catalytic models and data for SAT2, SAT3, and A to catalytic models, all of which quantified the time-variation in the force of infection using a b-spline. Since local minima and maxima in the force of infection did not occur at the same ages across serotypes, we infer that the force of infection is time-varying. Between 1996 and 2010, estimates for the FOI for SAT1 decrease through time while estimates for the FOI for SAT2 and SAT3 increase through time (Fig 2). Type O shows cyclic variation in the estimated FOI though time, and type A shows two distinct peaks of estimated FOI: one between 2000 and 2002 and the other between 2008 and 2010. Simulations using the better-fit version of the catalytic model with estimated values for the duration of seropositivity after natural infection and serotype-specific time-varying FOI produced a good fit with the data (Fig 3). The mean estimated FOI ranged from the maximum of 0.69 per year for type O to a minimum of 0.021 per year for SAT 2 (Table 3). Therefore, there are clear serotype specific differences in the FOI with regards to magnitude and temporal patterns.

Bottom Line: For serotypes SAT2, SAT3, and type A, a model assuming life-long immunity fit better.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Veterinary Preventive Medicine, Ohio State University, Columbus, OH, United States of America.

ABSTRACT
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.

No MeSH data available.


Related in: MedlinePlus