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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.

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Schematics depicting transitions of humans and mosquitoes between different compartments (solid lines), transmission of malaria from infectious mosquitoes to susceptible humans (dashed line), and transmission of malaria from infectious and immune humans to susceptible mosquitoes (dash-dotted lines). Mortalities are denoted by dotted lines. The transition and mortality rates are described in Table 1 and the total human and mosquito populations are, respectively, Nh = Sh + Eh + Ih + Rh and Nv = Sv + Ev + Iv.
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Figure 1: Schematics depicting transitions of humans and mosquitoes between different compartments (solid lines), transmission of malaria from infectious mosquitoes to susceptible humans (dashed line), and transmission of malaria from infectious and immune humans to susceptible mosquitoes (dash-dotted lines). Mortalities are denoted by dotted lines. The transition and mortality rates are described in Table 1 and the total human and mosquito populations are, respectively, Nh = Sh + Eh + Ih + Rh and Nv = Sv + Ev + Iv.

Mentions: The human population is described by four classes such that at time t ≥0, there are Sh(t) susceptible, Eh(t) exposed, Ih(t) infectious, and Rh(t) immune humans. Malaria does not confer permanent immunity, thus, immunity in this work refers to partial immunity. Note that immunity to malaria is sustained by continuous exposure to infection (Aron, 1983). The mosquito population is divided into three classes such that at time t ≥0, there are Sv(t) susceptible, Ev(t) exposed and Iv(t) infectious mosquitoes. With these divisions, the total human and mosquito populations at time t, are Nh(t) = Sh(t)+Eh(t)+Ih(t)+Rh(t) and Nv(t) = Sv (t)+Ev(t)+Iv(t), respectively. Note that the subscripts h and v refer to humans and mosquitoes, respectively. See Table 1 for brief descriptions, baseline values and ranges of values of the parameters used in the model and Fig. 1 for schematics of the model.


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)

Schematics depicting transitions of humans and mosquitoes between different compartments (solid lines), transmission of malaria from infectious mosquitoes to susceptible humans (dashed line), and transmission of malaria from infectious and immune humans to susceptible mosquitoes (dash-dotted lines). Mortalities are denoted by dotted lines. The transition and mortality rates are described in Table 1 and the total human and mosquito populations are, respectively, Nh = Sh + Eh + Ih + Rh and Nv = Sv + Ev + Iv.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Schematics depicting transitions of humans and mosquitoes between different compartments (solid lines), transmission of malaria from infectious mosquitoes to susceptible humans (dashed line), and transmission of malaria from infectious and immune humans to susceptible mosquitoes (dash-dotted lines). Mortalities are denoted by dotted lines. The transition and mortality rates are described in Table 1 and the total human and mosquito populations are, respectively, Nh = Sh + Eh + Ih + Rh and Nv = Sv + Ev + Iv.
Mentions: The human population is described by four classes such that at time t ≥0, there are Sh(t) susceptible, Eh(t) exposed, Ih(t) infectious, and Rh(t) immune humans. Malaria does not confer permanent immunity, thus, immunity in this work refers to partial immunity. Note that immunity to malaria is sustained by continuous exposure to infection (Aron, 1983). The mosquito population is divided into three classes such that at time t ≥0, there are Sv(t) susceptible, Ev(t) exposed and Iv(t) infectious mosquitoes. With these divisions, the total human and mosquito populations at time t, are Nh(t) = Sh(t)+Eh(t)+Ih(t)+Rh(t) and Nv(t) = Sv (t)+Ev(t)+Iv(t), respectively. Note that the subscripts h and v refer to humans and mosquitoes, respectively. See Table 1 for brief descriptions, baseline values and ranges of values of the parameters used in the model and Fig. 1 for schematics of the model.

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