Abstract: In this paper, we analyse the stability of the SEIR model
of malaria with infective immigrants which was recently formulated
by the authors. The model consists of an SEIR model for the human
population and SI Model for the mosquitoes. Susceptible humans
become infected after they are bitten by infectious mosquitoes and
move on to the Exposed, Infected and Recovered classes respectively.
The susceptible mosquito becomes infected after biting an infected
person and remains infected till death. We calculate the reproduction
number R0 using the next generation method and then discuss about
the stability of the equilibrium points. We use the Lyapunov function
to show the global stability of the equilibrium points.
Abstract: This paper proposes and analyzes an SIRS epidemic model incorporating the effects of the awareness programs driven by the media. Media and media driven awareness programs play a promising role in disseminating the information about outbreak of any disease across the globe. This motivates people to take precautionary measures and guides the infected individuals to get hospitalized. Timely hospitalization helps to reduce diagnostic delays and hence results in fast recovery of infected individuals. The aim of this study is to investigate the impact of the media on the spread and control of infectious diseases. This model is analyzed using stability theory of differential equations. The sensitivity of parameters has been discussed and it has been found that the awareness programs driven by the media have positive impact in reducing the infection prevalence of the infective population in the region under consideration.
Abstract: The main aim of this study is to describe and introduce a method of numerical analysis in obtaining approximate solutions for the SIR-SI differential equations (susceptible-infectiverecovered for human populations; susceptible-infective for vector populations) that represent a model for dengue disease transmission. Firstly, we describe the ordinary differential equations for the SIR-SI disease transmission models. Then, we introduce the numerical analysis of solutions of this continuous time, discrete space SIR-SI model by simplifying the continuous time scale to a densely populated, discrete time scale. This is followed by the application of this numerical analysis of solutions of the SIR-SI differential equations to the estimation of relative risk using continuous time, discrete space dengue data of Kuala Lumpur, Malaysia. Finally, we present the results of the analysis, comparing and displaying the results in graphs, table and maps. Results of the numerical analysis of solutions that we implemented offers a useful and potentially superior model for estimating relative risks based on continuous time, discrete space data for vector borne infectious diseases specifically for dengue disease.
Abstract: Fungal infections are becoming more common and the
range of susceptible individuals has expanded. While Candida
albicans remains the most common infective species, other Candida
spp. are becoming increasingly significant. In a range of large-scale
studies of candidaemia between 1999 and 2006, about 52% of 9717
cases involved C. albicans, about 30% involved either C. glabrata or
C. parapsilosis and less than 15% involved C. tropicalis, C. krusei or
C. guilliermondii. However, the probability of mortality within 30
days of infection with a particular species was at least 40% for C.
tropicalis, C. albicans, C. glabrata and C. krusei and only 22% for
C. parapsilopsis. Clinical isolates of Candida spp. grew at rates
ranging from 1.65 h-1 to 4.9 h-1. Three species (C. krusei, C. albicans
and C. glabrata) had relatively high growth rates (μm > 4 h-1), C.
tropicalis and C. dubliniensis grew moderately quickly (Ôëê 3 h-1) and
C. parapsilosis and C. guilliermondii grew slowly (< 2 h-1). Based
on these data, the log of the odds of mortality within 30 days of
diagnosis was linearly related to μm. From this the underlying
probability of mortality is 0.13 (95% CI: 0.10-0.17) and it increases
by about 0.09 ± 0.02 for each unit increase in μm. Given that the
overall crude mortality is about 0.36, the growth of Candida spp.
approximately doubles the rate, consistent with the results of larger
case-matched studies of candidaemia.
Abstract: The functional response of an infective is the relationship
between an infected individual-s infection rate and the abundance
of the number of susceptibles that one can potentially be infected.
In this paper, we consider defensive attitudes for HIV prevention
(primary prevention) while at the same time emphasizing on offensive
attitudes that reduce infection for those infected (secondary prevention).
We look at how defenses can protect an uninfected individual
in the case where high risk groups such as commercial sex workers
and those who deliberately go out to look for partners. We propose
an infection cycle that begins with a search, then an encounter,
a proposal and contact. The infection cycle illustrates the various
steps an infected individual goes through to successfully infect a
susceptible. For heterogeneous transmission of HIV, there will be no
infection unless there is contact. The ability to avoid an encounter,
detection, proposal and contact constitute defense.