This model is appropriate for a disease that spreads through human populations by direct contact between infectious individuals and susceptible individuals
, such as influenza.
New susceptible individuals
enter the subgroup S(t) at a constant rate of A through birth or immigration.
Risk, as measured by incidence, can be estimated from the model as the per capita transmission rate of susceptible individuals
into the infectious state.
In such interactions information, behavioral innovation, belief, or meme is transmitted in a similar way to infectious diseases spread in groups of susceptible individuals
Gielen  further proposed an interesting variant of the above model for a small epidemic in a large population of susceptible individuals
. This model can be seen to be the direct stochastic version of the Keyfitz  deterministic model, governed by the renewal equation:
Vartanian elaborates, "We hope that in two or three years, we and others will be able to determine whether epsilon toxin is truly associated with MS, which would give us a critical new pathway to developing strategies to [block this toxin]." This capability in turn could prevent lesion formation and, ideally, development of MS in susceptible individuals
Malignant hyperthermia is reportedly a condition that can be triggered when genetically susceptible individuals
come in contact with certain inhaled (volatile) anesthetics or the muscle relaxant succinylcholine.
For the case where an epidemic is observed fully over a given time interval such that all infection and removal times are known,  provided martingale estimating equations to propose an estimator called the M-estimator of the initial number of susceptible individuals
and its approximate variance.
So, as soon as the susceptible individuals
begin the vaccination process, they are different from susceptible individuals
A large, randomised controlled trial is being conducted in 10 European countries to clarify whether breastfeeding and early gluten introduction are effective in preventing CD in genetically susceptible individuals
. World Rev Nutr Diet 2013 108: 91-7.
AIM: Idiopathic photodermatoses (IP) are a recurrent, acquired sunlight-induced rash of delayed onset, appearing after exposure to ultraviolet radiation in susceptible individuals
. The aim of this study was to assess the photoprotective activity of polypodium leucotomos (PL) in IP.
With the prevalence in US as 1 in 88 children, a majority of cases with idiopathic autism likely result from an unknown environmental trigger in genetically susceptible individuals
. Environmental maternal exposure of a fetus to minute concentrations of pharmaceuticals and personal care products (PPCPs) and other compounds is an interesting possibility.