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Nipah virus (NiV) is a zoonotic virus that causes outbreaks of fatal disease in humans. Fruit bat, also known as the flying fox, is the animal host reservoir for NiV. It is known to cause illness in pigs, which are considered an intermediate host. In this paper, we propose a model for NiV disease transmission taking into account all human-to-host animal transmission as well as the loss of immunity in those who have recovered. Furthermore, we take into consideration seasonal effects such as varying transmission rate from bats and birth rate of bats. We studied the existence and uniqueness of a diseasefree ω-periodic solution and later deals with the basic reproduction number and stability analysis. To support the analytical results we provide numerical examples and assess the effect of parameter changes on disease dynamics, which might help to understand how to avoid a yearly periodic recurrence of the disease. [ABSTRACT FROM AUTHOR]

Relative to the number of casualties, COVID-19 ranks among the ten most devastating plagues in history. The pandemic hit the South Asian nation of Bangladesh in early March 2020 and has greatly impacted the socio-economic status of the country. In this article, we propose a compartmental model for COVID-19 dynamics, introducing a separate class for quarantined susceptibles, synonymous to isolation of individuals who have been exposed and are suspected of being infected. The current model assumes a perfect quarantine based on contact with infectious individuals. Numerical simulation is conducted to investigate the efficiency of disease control by segregating suspected individuals and other non-pharmaceutical interventions. In addition, we assort quantitatively the importance of parameters that inuence the dynamics of the system. Fitting the system to the early phase of COVID-19 outbreaks in Bangladesh, by taking into account the cumulative number of cases with the data of the first 17-week period, the basic reproduction number is estimated as 1.69. [ABSTRACT FROM AUTHOR]

We present a periodic nonlinear scalar delay differential equation model for a population with short reproduction period. By transforming the equation to a discrete dynamical system, we reduce the infinite dimensional problem to one dimension. We determine the basic reproduction number not merely as the spectral radius of an operator, but as an explicit formula and show that is serves as a threshold parameter for the stability of the trivial equilibrium and for permanence. [ABSTRACT FROM AUTHOR]