Yet cholera is persisting – and while the number of cases in Luanda and the other most affected provinces is decreasing, the epidemic continues to spread to new parts of the country.
A higher level of structuring of the population into classes is expected to decrease the epidemic sizes per comparable groups of classes, and to increase the probability of extinction of the epidemic, with respect to our predictions (see for instance the discussions in [ 35, 55, 56] and references therein).
Indeed the addition of edges to a network can only decrease the epidemic threshold.
However, in the absence of compensatory mutations, increasing treatment level would continue to decrease the epidemic size (Figure 3a, dashed curves), as resistant strains exist only at significantly lower transmission fitness compared with the wild-type strain.
Similarly, it is conceivable that large-scale real-life events can impact method effectiveness; for example, a natural disaster can deplete coping resources, resulting in a low effect size in a given study or perhaps even a set of studies; and it has been found that HIV risk behaviour interventions' effectiveness decreased with epidemic duration (Lacroix, Pellowski, Lennon, & Johnson, 2013).
We demonstrate the broad applicability of our methodology using a diverse array of compartmental epidemic models: a time-homogeneous SIS epidemic, a time-inhomogeneous SI epidemic with exponentially decreasing transmission rates and a partially observed SIR epidemic where the infectious period for an individual has a gamma distribution.
However, observing the evolution of an increase in virulence (instead of a decrease) as the epidemic matures would support the invasion threshold model for the initial virulence, because the Lenski May optima shift toward decreasing virulence as the epidemic matures.
The stable high level of preventive measures is in line with the earlier studies on SARS in Hong Kong where these measures remained high during the epidemic and, as Leung showed, only decreased after the epidemic ended [ 36].
In parallel to this demographic transition, however, the HIV/AIDS epidemic is decreasing the supply of family caregivers.
Triangulation exercises usually and logically begin with very broad questions: Is the HIV epidemic increasing, decreasing, or stabilizing nationally?
