WKB calculation of an epidemic outbreak distribution

WKB calculation of an epidemic outbreak distribution

We calculate both the exponential and pre-factor contributions in a WKB approximation of the master equation for a stochastic SIR model with highly oscillatory dynamics. Fixing the basic parameters of the model we investigate how the outbreak distribution changes with the population size. We show that this distribution rapidly becomes highly non-Gaussian, acquiring large tails indicating the pr...

An Outbreak of Epidemic Dropsy

Chopra et al. (1939) showed, by a controlled feeding experiment in man, that argemone oil (expressed from the seeds of a weed Argemone mexicana) produces symptoms resembling those of epidemic dropsy. In this experiment five individuals, who ate food cooked in mustard oil containing known quantities of argemone oil, developed well-marked oedema and two of them showed the characteristic flushed a...

An Outbreak of Epidemic Jaundice

An Outbreak of Epidemic Keratoconjunctivitis at an Outpatient Ophthalmology Clinic

Epidemic keratoconjunctivitis (EKC) is an acute eye infection caused by adenovirus. We investigated an outbreak of EKC at an outpatient ophthalmology practice in the context of a suspected community wide increase in EKC activity. A site visit was made to the facility reporting the outbreak. A line list was created of patients clinically diagnosed with EKC at the practice during the previous 5 m...

WKB theory of epidemic fade-out in stochastic populations.

Stochastic effects may cause "fade-out" of an infectious disease in a population immediately after an epidemic outbreak. We evaluate the epidemic fade-out probability by a WKB method and find that the most probable path to extinction of the disease comes from an instantonlike orbit in the phase space of an underlying Hamiltonian flow.