Using epidemiological mathematical models to understand the transmission dynamics of bovine tuberculosis in buffalo and cattle populations.

In South Africa, buffalo are maintenance hosts for Mycobacterium bovis (M. bovis), a pathogen that causes bovine tuberculosis in wild and domestic animals. The models address various questions about the transmission dynamics of bovine tuberculosis in both buffalo and cattle populations. The key questions addressed by the models are: can buffalo carriers fuel the re-emergence of bovine tuberculosis in the buffalo population.

Is the cross-infection transmission route responsible for the continuation of bovine tuberculosis in the cattle population. Could the movement of buffalo from one area to another be the reason for the spread of bovine tuberculosis in the Kruger National Park. Both mathematical and numerical analyzes suggest that infection parameters associated with buffalo carriers and cross-infection and movement parameters associated with movement of susceptible and exposed buffalo from one area to another are among the main drivers of bovine tuberculosis. in buffalo and cattle populations.

If bovine tuberculosis is to be eliminated, there is a need to develop tests that can detect buffalo carriers from the buffalo population. I am especially grateful and respectful to all my schoolmates in the Galileo building for being supportive and kind to me during my stay at the University of KwaZulu-Natal.

Background

Epidemiology of bovine tuberculosis in Africa and other continents

One of the reasons for failure is the high cost of sustainable testing procedures, as well as logistical inputs and financial constraints [7, 17]. Data on the prevalence of bovine tuberculosis in developing countries are generally scarce, but data on the incidence of BTB are available. Out of 55 African countries, 25 have reported occasional occurrence of BTB infection; six reported enzootic disease, two were reported to have high prevalence, four reported no disease, and the remaining 18 countries had no data.

Of the total Asian cattle and buffalo population, 6% and less than 1%, respectively, are in countries where bovine TB is notifiable and a test-and-slaughter policy is in place. Of these populations, 94% of cattle and more than 99% of buffaloes are only partially controlled for bovine TB or not at all [5]. This poses a great risk of spreading BTB infection to humans.

Similar trends in the prevalence of BTB infection in Latin America were also observed. Subsequently, great interest and dedication is devoted to studies that reveal the main drivers of disease in buffaloes and cattle.

Figure 1.1: Bovine tuberculosis occurance, Africa [5].

Epidemiology of bovine tuberculosis in Kruger National Park

Bovine tuberculosis infection is said to have been introduced into the park via cross-grazing between cattle and buffalo in the far south of KNP near Crocodile Bridge before the 1960s (see Figure 1.2). By the late 1980s, BTB infection had been largely eliminated from domestic animal populations around KNP, but within KNP it continued undetected. The survey conducted in 1991/92 showed the wildfire-like spread of BTB infection to the north of the park.

The central part of the park was moderately infected with an incidence of 4.4% while 0% incidence of the BTB infection was found in the northern part of the park. The chronological events of the occurrence of BTB infection in all three regions of the. The spreading trend of the BTB infection and its spillover effects have scientists worried.

The ecotourism aspect of the park has also been hit hard as a large number of lions have been infected. This is one of the reasons that has led to increased research activities on bovine tuberculosis in the Kruger National Park to understand the transmission dynamics of the disease.

Figure 1.2: The map showing the spread of bovine tuberculosi in Kruger National Park [18]

Bovine tuberculosis in cattle population

Biology of Mycobacterium bovis

Under moist conditions, especially those where oxygen and organic matter are present, the survival time of the pathogen increases. Maintenance hosts include the possum in New Zealand, badgers in Ireland and the UK, Kudu in Zambia, cervids in the USA and African buffalo in South Africa [ 3 , 4 ]. It is the existence of maintenance hosts that has led to the failure of many intervention programs to eradicate bovine tuberculosis in developed countries.

Other species have been identified as hosts or dead ends, such as humans, coyotes, and cats. In spillover hosts, infection in the population cannot persist indefinitely unless there is reinfection from another species or a change in the population that increases interspecies transmission [4]. Some animals appear asymptomatic during infection, while others may progress rapidly.

Aerosolization is thought to be the most infectious route of transmission and is responsible for 80 to 90% of infections in cattle [13]. Eating poorly cooked meat and drinking contaminated milk is another route that transmits infection to humans [4].

Metapopulations

His model was based on a population in which individuals reproduce and die in local parts of the habitat, and their descendants disperse to other areas. The rate of change in dpdt is given by the difference between the colonization rate and the extinction rate of E. This is analogous to the population growth rate as the difference between birth and death rates [12].

In this model, the colonization rate depends on the number of occupied and unoccupied sites. It was used in the field of mathematical epidemiology because of: (i) The initial disease conditions are often heterogeneous, with the disease spreading geographically over time. For example, the Black Death spread from east to west and from south to north along the trade routes of Europe between 1347 and 1350, and fox rabies spread westward from the Russian-Polish border in 1940 to reach France in 1968; (ii) The environment itself is heterogeneous, both in a geographical sense and in a human sense, with birth rates, death rates and health care facilities varying depending on location; iii) Several species have high movement speeds, a factor that plays a major role in diseases involving many species, for example the 2001 outbreak of foot-and-mouth disease in Great Britain and vector-borne diseases; and (iv) For human diseases, social groupings and mixing patterns vary with geography and age.

The first approach uses continuous-time continuous-space models yielding partial differential equations of the reaction-diffusion type. The approach to be used in any modeling project depends on the questions to be addressed and the experience of the modeler.

Motivation

Objectives of the study

Outline of this work

Publications

Progression to carrier buffalo occurs when the infectious buffalo recover from the lesions so that their infectivity is reduced, but they continue to shed M. The carrier buffalo may die naturally or die of BTB infection at a certain rate. To guarantee global asymptotic stability of the disease-free state, we rewrite model (3) in the form. The simulations allowed us to observe the effect of parameters on the dynamics of transmission of bovine tuberculosis in the buffalo population.

Sensitivity analysis also revealed that β is among the parameters driving the transmission dynamics of BTB infection. Tuberculosis in buffalo (syncerus caffer) in Kruger National Park: Spread of the disease to other species. This work aims to improve the understanding of the transmission dynamics of BTB infection through mathematical models.

Is cross-contamination of BTB infection from buffalo responsible for higher incidence of the infection in cattle. Since sub-model (5) monitors the cattle population, we assume that all state variables and parameters are positive for timeτ > 0. The bovine tuberculosis transmission sub-model will then be analyzed in a suitable feasible region given by. To prove the global asymptotic stability of the disease-free equilibrium point, we rewrite the model (4) in the form.

To explore the role of transmission rate between Bbon buffalo, the dynamics of BTB infection in buffalo only and the infectious unit in the environment,. The results show an increase in the percentage of exposed and infected buffalo in Figure 4 (b) and (c). These play a key role in modeling the metapopulation transmission dynamics of bovine tuberculosis through the generation of.

Therefore, all solutions start and remain in Ω. The guide to proving positivity and bounds of solutions can be found at. As before, the endemic interior equilibrium point is written in terms of the infection forces (λ∗1, λ∗2).Coordinates. of the equilibrium point are given as follows: where the constants in our endemic equilibrium coordinates are defined in the appendix. Tuberculosis in water buffalo (Syncerus caffer) in the Kruger National Park: spread of the disease to other species.

This biological aspect of the infection can, if incorporated into the model, improve the understanding of the transmission dynamics of bovine tuberculosis. The zoonotic effect of the disease was not taken into account in the models developed in this thesis. Tuberculosis in buffalo (syncerus caffer) in the Kruger National Park: spread of the disease to other species.

Epidemiological studies on tuberculosis in buffalo population in villages around Faisalabad.The Journal of Animal and plant sciences.