Limits...
The potential impact of HPV-16 reactivation on prevalence in older Australians.

Korostil IA, Regan DG - BMC Infect. Dis. (2014)

Bottom Line: The prevalence of HPV-16 in older Australian women will increase by a factor of up to 3.1 between now and 2025 which will be accompanied by an increase by a factor of around 1.9 in older men.If the reactivation hypothesis we consider is substantiated, the public health response should be focused on further improvement of cervical screening coverage for older women.Our study also highlights the urgent need for surveillance of HPV prevalence in older Australians.

View Article: PubMed Central - HTML - PubMed

Affiliation: The Kirby Institute, University of New South Wales, 2052 Sydney, Australia. ikorostil@kirby.unsw.edu.au.

ABSTRACT

Background: Some regional cross-sectional human papillomavirus (HPV) DNA prevalence data show an increase in prevalence in older women, the reasons for which are as yet unknown. A recently published study suggests that the increase may be at least partly due to reactivation of latent HPV in menopausal women.

Methods: We developed a dynamic mathematical model of HPV-16 transmission to estimate the key consequences of hypothetical HPV-16 reactivation in the Australian heterosexual population. We only consider a worst case scenario with regard to reactivation in the Australian setting when all women who are latently infected reactivate and, wherever feasible, we choose model parameter values which may lead to a more pronounced reactivation. The ongoing National HPV vaccination program covering both women and men is incorporated in the model.

Results: We estimate that about 1 in 10 women and men who appear to have cleared HPV-16 infection may be latently infected. The prevalence of HPV-16 in older Australian women will increase by a factor of up to 3.1 between now and 2025 which will be accompanied by an increase by a factor of around 1.9 in older men. However, the long-term impact of the HPV vaccination is not significantly altered by reactivation.

Conclusions: If the reactivation hypothesis we consider is substantiated, the public health response should be focused on further improvement of cervical screening coverage for older women. Our study also highlights the urgent need for surveillance of HPV prevalence in older Australians.

Show MeSH

Related in: MedlinePlus

Schematic diagram of the HPV-16 transmission model for females (left) and males (right). Here λw and λm are the forces of infection (i.e. the rates of becoming infected) for women and men,  is an additional force of infection acting on older men whose partners become infected via reactivation, and other parameters are as in Table 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4061121&req=5

Figure 1: Schematic diagram of the HPV-16 transmission model for females (left) and males (right). Here λw and λm are the forces of infection (i.e. the rates of becoming infected) for women and men, is an additional force of infection acting on older men whose partners become infected via reactivation, and other parameters are as in Table 1.

Mentions: We developed a dynamic compartmental mathematical model of HPV-16 transmission in the Australian heterosexual population. The model is illustrated schematically in Figure 1. This model is essentially of SIRS (Susceptible-Infected-Removed (Immune)-Susceptible) structure with waning natural immunity [10], extended to incorporate the possibility that HPV-16 may enter a latent undetectable state and subsequently reactivate (in women). The SIRS structure, while not the only plausible representation of HPV natural history [11], was chosen because it has been the most widely used (see, for example, [12] for a review). This structure has the advantage that when natural immunity wanes very slowly, the model approximates the SIR structure (life-long immunity) and if waning occurs very quickly, it approaches the SIS structure (no immunity). Our model incorporates both reactivation and reinfection, and we do not impose a priori the extent to which either should prevail. Susceptible women and men in the model may become infected and then some of them clear the infection completely and become immune, while others enter a latent infected state in which it is assumed that they would not test DNA positive due to viral load falling below the detectable threshold.


The potential impact of HPV-16 reactivation on prevalence in older Australians.

Korostil IA, Regan DG - BMC Infect. Dis. (2014)

Schematic diagram of the HPV-16 transmission model for females (left) and males (right). Here λw and λm are the forces of infection (i.e. the rates of becoming infected) for women and men,  is an additional force of infection acting on older men whose partners become infected via reactivation, and other parameters are as in Table 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4061121&req=5

Figure 1: Schematic diagram of the HPV-16 transmission model for females (left) and males (right). Here λw and λm are the forces of infection (i.e. the rates of becoming infected) for women and men, is an additional force of infection acting on older men whose partners become infected via reactivation, and other parameters are as in Table 1.
Mentions: We developed a dynamic compartmental mathematical model of HPV-16 transmission in the Australian heterosexual population. The model is illustrated schematically in Figure 1. This model is essentially of SIRS (Susceptible-Infected-Removed (Immune)-Susceptible) structure with waning natural immunity [10], extended to incorporate the possibility that HPV-16 may enter a latent undetectable state and subsequently reactivate (in women). The SIRS structure, while not the only plausible representation of HPV natural history [11], was chosen because it has been the most widely used (see, for example, [12] for a review). This structure has the advantage that when natural immunity wanes very slowly, the model approximates the SIR structure (life-long immunity) and if waning occurs very quickly, it approaches the SIS structure (no immunity). Our model incorporates both reactivation and reinfection, and we do not impose a priori the extent to which either should prevail. Susceptible women and men in the model may become infected and then some of them clear the infection completely and become immune, while others enter a latent infected state in which it is assumed that they would not test DNA positive due to viral load falling below the detectable threshold.

Bottom Line: The prevalence of HPV-16 in older Australian women will increase by a factor of up to 3.1 between now and 2025 which will be accompanied by an increase by a factor of around 1.9 in older men.If the reactivation hypothesis we consider is substantiated, the public health response should be focused on further improvement of cervical screening coverage for older women.Our study also highlights the urgent need for surveillance of HPV prevalence in older Australians.

View Article: PubMed Central - HTML - PubMed

Affiliation: The Kirby Institute, University of New South Wales, 2052 Sydney, Australia. ikorostil@kirby.unsw.edu.au.

ABSTRACT

Background: Some regional cross-sectional human papillomavirus (HPV) DNA prevalence data show an increase in prevalence in older women, the reasons for which are as yet unknown. A recently published study suggests that the increase may be at least partly due to reactivation of latent HPV in menopausal women.

Methods: We developed a dynamic mathematical model of HPV-16 transmission to estimate the key consequences of hypothetical HPV-16 reactivation in the Australian heterosexual population. We only consider a worst case scenario with regard to reactivation in the Australian setting when all women who are latently infected reactivate and, wherever feasible, we choose model parameter values which may lead to a more pronounced reactivation. The ongoing National HPV vaccination program covering both women and men is incorporated in the model.

Results: We estimate that about 1 in 10 women and men who appear to have cleared HPV-16 infection may be latently infected. The prevalence of HPV-16 in older Australian women will increase by a factor of up to 3.1 between now and 2025 which will be accompanied by an increase by a factor of around 1.9 in older men. However, the long-term impact of the HPV vaccination is not significantly altered by reactivation.

Conclusions: If the reactivation hypothesis we consider is substantiated, the public health response should be focused on further improvement of cervical screening coverage for older women. Our study also highlights the urgent need for surveillance of HPV prevalence in older Australians.

Show MeSH
Related in: MedlinePlus