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The impact of IPTi and IPTc interventions on malaria clinical burden - in silico perspectives.

Aguas R, Lourenço JM, Gomes MG, White LJ - PLoS ONE (2009)

Bottom Line: Here, we simulate several schemes of intervention under different transmission settings, while varying immunity build up assumptions.However, even when significant rebound effects are predicted to occur, the overall intervention impact is positive.On the contrary, IPTc has a significant potential to reduce transmission, specifically in areas where it is already low to moderate.

View Article: PubMed Central - PubMed

Affiliation: Instituto Gulbenkian de Ciência, Oeiras, Portugal. ricaguas@igc.gulbenkian.pt

ABSTRACT

Background: Clinical management of malaria is a major health issue in sub-Saharan Africa. New strategies based on intermittent preventive treatment (IPT) can tackle disease burden by simultaneously reducing frequency of infections and life-threatening illness in infants (IPTi) and children (IPTc), while allowing for immunity to build up. However, concerns as to whether immunity develops efficiently in treated individuals, and whether there is a rebound effect after treatment is halted, have made it imperative to define the effects that IPTi and IPTc exert on the clinical malaria scenario.

Methods and findings: Here, we simulate several schemes of intervention under different transmission settings, while varying immunity build up assumptions. Our model predicts that infection risk and effectiveness of acquisition of clinical immunity under prophylactic effect are associated to intervention impact during treatment and follow-up periods. These effects vary across regions of different endemicity and are highly correlated with the interplay between the timing of interventions in age and the age dependent risk of acquiring an infection. However, even when significant rebound effects are predicted to occur, the overall intervention impact is positive.

Conclusions: IPTi is predicted to have minimal impact on the acquisition of clinical immunity, since it does not interfere with the occurrence of mild infections, thus failing to reduce the underlying force of infection. On the contrary, IPTc has a significant potential to reduce transmission, specifically in areas where it is already low to moderate.

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Related in: MedlinePlus

Impact of an IPTc strategy apllied in 5 to 18 years old children on clinical malaria age profiles, and over time.Age profiles of populations under an IPTc intervention calibrated from data in Clarke et al. [19] are compared with populations without intervention, represented by black lines. (A) Clinical malaria age profiles, retrieved immediately after the third dose of treatment (blue line), and 4 months after the administration of that course of drug (red line). (B) Represents the same as (A), but for a high transmission setting. (C), (D) Time dynamics of IPTc impact over all age classes in mild and intense malaria transmission areas, respectively. Intervention (starting in year 1) shapes the dynamics of both clinical (blue line) and asymptomatic/mild (red line) malaria. The dashed lines represent unperturbed equilibria.
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pone-0006627-g005: Impact of an IPTc strategy apllied in 5 to 18 years old children on clinical malaria age profiles, and over time.Age profiles of populations under an IPTc intervention calibrated from data in Clarke et al. [19] are compared with populations without intervention, represented by black lines. (A) Clinical malaria age profiles, retrieved immediately after the third dose of treatment (blue line), and 4 months after the administration of that course of drug (red line). (B) Represents the same as (A), but for a high transmission setting. (C), (D) Time dynamics of IPTc impact over all age classes in mild and intense malaria transmission areas, respectively. Intervention (starting in year 1) shapes the dynamics of both clinical (blue line) and asymptomatic/mild (red line) malaria. The dashed lines represent unperturbed equilibria.

Mentions: IPTc intervention significantly disturbs the age dependent risk of acquiring a malaria infection, which can be translated into age profiles of clinical episodes as those in Figures 5–7.


The impact of IPTi and IPTc interventions on malaria clinical burden - in silico perspectives.

Aguas R, Lourenço JM, Gomes MG, White LJ - PLoS ONE (2009)

Impact of an IPTc strategy apllied in 5 to 18 years old children on clinical malaria age profiles, and over time.Age profiles of populations under an IPTc intervention calibrated from data in Clarke et al. [19] are compared with populations without intervention, represented by black lines. (A) Clinical malaria age profiles, retrieved immediately after the third dose of treatment (blue line), and 4 months after the administration of that course of drug (red line). (B) Represents the same as (A), but for a high transmission setting. (C), (D) Time dynamics of IPTc impact over all age classes in mild and intense malaria transmission areas, respectively. Intervention (starting in year 1) shapes the dynamics of both clinical (blue line) and asymptomatic/mild (red line) malaria. The dashed lines represent unperturbed equilibria.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2722080&req=5

pone-0006627-g005: Impact of an IPTc strategy apllied in 5 to 18 years old children on clinical malaria age profiles, and over time.Age profiles of populations under an IPTc intervention calibrated from data in Clarke et al. [19] are compared with populations without intervention, represented by black lines. (A) Clinical malaria age profiles, retrieved immediately after the third dose of treatment (blue line), and 4 months after the administration of that course of drug (red line). (B) Represents the same as (A), but for a high transmission setting. (C), (D) Time dynamics of IPTc impact over all age classes in mild and intense malaria transmission areas, respectively. Intervention (starting in year 1) shapes the dynamics of both clinical (blue line) and asymptomatic/mild (red line) malaria. The dashed lines represent unperturbed equilibria.
Mentions: IPTc intervention significantly disturbs the age dependent risk of acquiring a malaria infection, which can be translated into age profiles of clinical episodes as those in Figures 5–7.

Bottom Line: Here, we simulate several schemes of intervention under different transmission settings, while varying immunity build up assumptions.However, even when significant rebound effects are predicted to occur, the overall intervention impact is positive.On the contrary, IPTc has a significant potential to reduce transmission, specifically in areas where it is already low to moderate.

View Article: PubMed Central - PubMed

Affiliation: Instituto Gulbenkian de Ciência, Oeiras, Portugal. ricaguas@igc.gulbenkian.pt

ABSTRACT

Background: Clinical management of malaria is a major health issue in sub-Saharan Africa. New strategies based on intermittent preventive treatment (IPT) can tackle disease burden by simultaneously reducing frequency of infections and life-threatening illness in infants (IPTi) and children (IPTc), while allowing for immunity to build up. However, concerns as to whether immunity develops efficiently in treated individuals, and whether there is a rebound effect after treatment is halted, have made it imperative to define the effects that IPTi and IPTc exert on the clinical malaria scenario.

Methods and findings: Here, we simulate several schemes of intervention under different transmission settings, while varying immunity build up assumptions. Our model predicts that infection risk and effectiveness of acquisition of clinical immunity under prophylactic effect are associated to intervention impact during treatment and follow-up periods. These effects vary across regions of different endemicity and are highly correlated with the interplay between the timing of interventions in age and the age dependent risk of acquiring an infection. However, even when significant rebound effects are predicted to occur, the overall intervention impact is positive.

Conclusions: IPTi is predicted to have minimal impact on the acquisition of clinical immunity, since it does not interfere with the occurrence of mild infections, thus failing to reduce the underlying force of infection. On the contrary, IPTc has a significant potential to reduce transmission, specifically in areas where it is already low to moderate.

Show MeSH
Related in: MedlinePlus