Limits...
Quantifying the impact of decay in bed-net efficacy on malaria transmission.

Ngonghala CN, Del Valle SY, Zhao R, Mohammed-Awel J - J. Theor. Biol. (2014)

Bottom Line: The potential impact of ITNs on reducing malaria transmission is limited due to inconsistent or improper use, as well as physical decay in effectiveness.We develop a model for malaria spread that captures the decrease in ITN effectiveness due to physical and chemical decay, as well as human behavior as a function of time.These analyses show that the basic reproduction number R0, and the infectious human population are most sensitive to bed-net coverage and the biting rate of mosquitoes.

View Article: PubMed Central - PubMed

Affiliation: Department of Global Health and Social Medicine, Harvard Medical School, Boston, MA 02115, USA; National Institute for Mathematical and Biological Synthesis, Knoxville, TN 37996-1527, USA. Electronic address: Calistus_Ngonghala@hms.harvard.edu.

Show MeSH

Related in: MedlinePlus

Simulation results illustrating the dynamics of the non-autonomous model (2.4) for the initial conditions  and the parameters in Table 1 with b0 = 0.6 and βmax = 0.5. (a) Dynamics for periodic time-dependent bβ and bμv showing a fast initial decline and damped secondary waves of infection over time. (b) Dynamics of system (2.4) for time-averaged bβ and bμv. The smaller plots highlight the decline in the exposed, infectious and immune populations.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4374367&req=5

Figure 9: Simulation results illustrating the dynamics of the non-autonomous model (2.4) for the initial conditions and the parameters in Table 1 with b0 = 0.6 and βmax = 0.5. (a) Dynamics for periodic time-dependent bβ and bμv showing a fast initial decline and damped secondary waves of infection over time. (b) Dynamics of system (2.4) for time-averaged bβ and bμv. The smaller plots highlight the decline in the exposed, infectious and immune populations.

Mentions: Fig. 9 compares the dynamics of system (2.4) for periodic time-dependent and averaged bβ and bμv. Fig. 9(a) shows a rapid decline in infection prevalence due to the high effectiveness of ITNs at the beginning of the policy implementation. However, as the effectiveness of the ITNs decreases, damped waves of infection are observed before the system relaxes to the disease-free equilibrium. Fig. 9(b) depicts a monotonic decline in disease prevalence. This implies that a strategy consisting of low ITN coverage and frequent replacement will not be as effective as one that involves high coverage initially and maintaining this level until the ITNs lose their effectiveness.


Quantifying the impact of decay in bed-net efficacy on malaria transmission.

Ngonghala CN, Del Valle SY, Zhao R, Mohammed-Awel J - J. Theor. Biol. (2014)

Simulation results illustrating the dynamics of the non-autonomous model (2.4) for the initial conditions  and the parameters in Table 1 with b0 = 0.6 and βmax = 0.5. (a) Dynamics for periodic time-dependent bβ and bμv showing a fast initial decline and damped secondary waves of infection over time. (b) Dynamics of system (2.4) for time-averaged bβ and bμv. The smaller plots highlight the decline in the exposed, infectious and immune populations.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4374367&req=5

Figure 9: Simulation results illustrating the dynamics of the non-autonomous model (2.4) for the initial conditions and the parameters in Table 1 with b0 = 0.6 and βmax = 0.5. (a) Dynamics for periodic time-dependent bβ and bμv showing a fast initial decline and damped secondary waves of infection over time. (b) Dynamics of system (2.4) for time-averaged bβ and bμv. The smaller plots highlight the decline in the exposed, infectious and immune populations.
Mentions: Fig. 9 compares the dynamics of system (2.4) for periodic time-dependent and averaged bβ and bμv. Fig. 9(a) shows a rapid decline in infection prevalence due to the high effectiveness of ITNs at the beginning of the policy implementation. However, as the effectiveness of the ITNs decreases, damped waves of infection are observed before the system relaxes to the disease-free equilibrium. Fig. 9(b) depicts a monotonic decline in disease prevalence. This implies that a strategy consisting of low ITN coverage and frequent replacement will not be as effective as one that involves high coverage initially and maintaining this level until the ITNs lose their effectiveness.

Bottom Line: The potential impact of ITNs on reducing malaria transmission is limited due to inconsistent or improper use, as well as physical decay in effectiveness.We develop a model for malaria spread that captures the decrease in ITN effectiveness due to physical and chemical decay, as well as human behavior as a function of time.These analyses show that the basic reproduction number R0, and the infectious human population are most sensitive to bed-net coverage and the biting rate of mosquitoes.

View Article: PubMed Central - PubMed

Affiliation: Department of Global Health and Social Medicine, Harvard Medical School, Boston, MA 02115, USA; National Institute for Mathematical and Biological Synthesis, Knoxville, TN 37996-1527, USA. Electronic address: Calistus_Ngonghala@hms.harvard.edu.

Show MeSH
Related in: MedlinePlus