Vetnews | Desember 2024 16 « BACK TO CONTENTS We compound veterinary medicines www.v-tech.co.za / Tel: +27 87 150 5925 (SA) The African buffalo is used to illustrate the principles of disease management. Epidemiological triangle The epidemiology of any infectious disease involves the complex interaction between factors of the host, agent (disease) and environment known as the epidemiological triangle. Therefore, for a disease to manifest there must be a susceptible host, an infective agent, and a vector to carry the agent to the host. Basic disease control means that one of the links in this triangle has to be broken. Disease transmission by arthropod vectors can occur by mechanical or biological means. Mechanical transmission involves the transfer of a pathogen by an external body part (e.g., legs) of the vector; the pathogen remains unchanged (i.e., does not replicate or develop further). Most species of flies serve as mechanical vectors. Biological transmission involves the alteration of the pathogen within the vector. The vector uptakes the pathogen - usually through a blood meal from an infected animal - and the pathogen undergoes further development or replication within the arthropod vector before being transferred to a susceptible animal, usually through a bite. Midges, ticks, and mosquitoes are common biological disease vectors. Additionally, myiasis - the infestation of the skin or wounds by fly larvae - can also be of great economic concern and can affect wildlife and domestic livestock. An effective biosecurity plan for wildlife includes the following elements; • How to receive and manage new animals on the ranch. • How to regulate movement on and off the ranch. • How to clean and disinfect equipment on the ranch to reduce pathogen levels. • How to monitor animal health on the ranch. The two key biosecurity measures are: 1. Minimising movement of animals, animal products, people, vehicles and equipment between premises where animals are kept. Part 2: Biosecurity and disease management for wildlife Dr Jacobus du Toit Agent Host Vector Figure 1: Epidemiological Triangle
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