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Additional Information about Infectious Diseases
Published in Lyle D. Broemeling, Bayesian Analysis of Infectious Diseases, 2021
The aim of this chapter is to describe the statistical analysis of observational information of the behavior of infectious diseases. A disease is infectious if the infected host transitions through an infectious period, during which the person is capable of passing the disease to a susceptible individual, either by direct contact or by infecting the surrounding environment in such a way that the person becomes infected. Another way for a person to contract a disease is by an intermediate vector, that is, the disease is carried by the vector which subsequently infects the host. For example, a mosquito which has malaria transmits the disease to another by biting the victim. The infected immediate surroundings might include linen and utensils of a household or the ambient air in the house.
Spatio-Temporal Analysis of Surveillance Data
Published in Leonhard Held, Niel Hens, Philip O’Neill, Jacco Wallinga, Handbook of Infectious Disease Data Analysis, 2019
Jon Wakefield, Tracy Qi Dong, Vladimir N. Minin
We will derive the probability that a susceptible individual at time will become infected by time . In contrast to the TSIR derivation, in which the process of the infectives infecting susceptibles was modeled (and lead to a negative binomial for the number of new infectives), the derivation here models the process of susceptibles becoming infected (and, as we will see, leads to a binomial distribution for the number of new infectives).
Sexually transmitted disease related emergencies
Published in Biju Vasudevan, Rajesh Verma, Dermatological Emergencies, 2019
STDs can have a plethora of extragenital clinical manifestations, many of which may present as emergency. The possibility of a STD leading to these manifestations in a susceptible individual must be borne in mind when such a condition is encountered.
Time fused coefficient SIR model with application to COVID-19 epidemic in the United States
Published in Journal of Applied Statistics, 2023
Hou-Cheng Yang, Yishu Xue, Yuqing Pan, Qingyang Liu, Guanyu Hu
The Susceptible–Infectious–Recovered [SIR; 12] model and its variants, such as Susceptible–Infected–Removed–Susceptible [SIRS; 13,14] and Susceptible–Exposed–Infected–Removal [SEIR; 9] models are commonly used to describe the dynamics of an infectious disease in a certain region. In the basic SIR model, a population is segregated into three time-dependent compartments including Susceptible (t, but may be infected due to contact with an infected person belongs to the susceptible compartment. The infected compartment is made up of those who have a disease at time t, and can potentially get a susceptible individual infected by contact. The recovered compartment include those who are either recovered or dead from the disease, and are no longer contagious, i.e. removed from the infectious compartment, at time t. Removal can be due to several possible reasons, including death, recovery with immunity against reinfection, and quarantine and isolation from the rest of the population. A recovered/removed individual will not be back into the susceptible compartment anymore. Such model assumption match well with the COVID-19 outbreak, and therefore we adopt the SIR model as our basic model in this paper.
How can proteomics overhaul our understanding of Leishmania biology?
Published in Expert Review of Proteomics, 2020
Paul W. Denny, Karunakaran Kalesh
The development and severity of clinical manifestations of leishmaniasis depend not only on the Leishmania spp. but on the many factors pertaining to the susceptible individual such as malnutrition, comorbidities and the state of the immune system. Leishmania spp. parasites have co-evolved with humans in endemic areas and this positive selection pressure has contributed to pathogen survival by latent infection. The development of post-Kala-azar dermal leishmaniasis (PKDL) in some visceral leishmaniasis (VL) patients after recovery from the VL, and the development of mucosal lesions in some individuals after several years or even decades of developing primary cutaneous lesions, are indicative of the ability of the parasite to persist within the host even after successful treatment of the initial clinical condition. Clearly, despite years of research, many aspects of the Leishmania-host interaction remain poorly understood. In principle, all antileishmanials that work purely by targeting a parasite protein are likely to eventually fail as the extraordinary genetic plasticity of Leishmania spp. will confer fitness gains enabling the parasite to effectively evolve toward drug-resistant phenotypes. Therefore, an alternative strategy of host-directed therapeutic development has been proposed to tackle this issue. However, in the first place this requires better understanding of the Leishmania-host interaction.
Determining optimal community protection strategies for the influenza vaccine
Published in Expert Review of Vaccines, 2019
Charlotte Switzer, Lorne Babiuk, Mark Loeb
Fine [37] developed the theory further, introducing the ‘basic case reproduction rate … [which] describes the spreading potential of an infection in a population’ (1993:272). This spreading potential would reflect both the mode of transmission and biological infectiousness; and the interaction rate of susceptibles in the host population, in keeping with parameters defined by Fox et al. Under real-world circumstances, it is likely that the contacts of a susceptible individual may already possess immunity, or be infected themselves. As such, the number of actual infections arising from a single infectious case will be less than the basic reproduction rate. This introduces a new consideration, the probability of effective contact, wherein the risk of infection is essentially the risk of an infectious case having effective contact with a susceptible. While the number of susceptibles fluctuates within populations and population subgroups, epidemic scale of new incident infections will not occur unless a critical mass of susceptibles is exceeded. This notion of critical mass, or an ‘epidemic threshold’, is the simplest quantification of herd immunity – ‘if the proportion immune is so high that the number of susceptibles is below the epidemic threshold, then incidence will decrease’ (1993:269).