BMS3001 – Infectious Disease Epidemiology: Zoonotic and Vector-Borne Diseases

BMS3001 – Infectious Disease Epidemiology Module 2: Modes of Transmission and Types of Disease

Topic 5 – Zoonotic and Vector-Borne Diseases (Lecture 1)

Learning Objectives

• Describe how zoonotic and vector-borne diseases are different from other infectious diseases.
    - Zoonotic diseases are those that are transmitted from animals to humans, while vector-borne diseases are those transmitted through vectors, such as mosquitoes or ticks. Understanding these distinctions is crucial in epidemiology for effective disease management.

• Deconstruct what it takes to vector a disease.
    - Vectoring involves multiple components, including the biological and environmental factors that enable the vector (e.g., mosquito) to transmit the pathogens from one host to another. This can involve the vector's lifecycle, habitat, behavior, and the presence of the pathogen within the vector.

• Articulate how zoonotic and vector-borne disease control approaches are similar to other disease control efforts. How are they different?
    - Control measures for zoonotic and vector-borne diseases often necessitate integrated strategies similar to those used for other infectious diseases. These approaches may include vaccination, habitat modification, vector control (fogging, larviciding), and public awareness campaigns. However, they also differ due to their reliance on animal populations and environmental factors, which must be accounted for in control strategies.

• Defend why and how zoonotic and vector-borne disease rely on eco-epidemiologic methods.
    - Eco-epidemiologic methods emphasize the interactions between pathogens, hosts, vectors, and environmental factors. Understanding these interactions is critical for predicting disease outbreaks and implementing targeted control measures, making them essential in zoonotic and vector-borne diseases.

Vector-Borne and Zoonotic Disease

• Definitions:
    - Vector-Borne Disease: An illness that is transmitted to humans or animals through a living organism known as a vector, which carries the disease-causing agent. Common vectors include mosquitoes, ticks, and fleas.
    - Zoonosis: A disease that can be transmitted from animals to humans. Zoonotic diseases may have various reservoirs in the animal kingdom, including mammals, birds, reptiles, and amphibians.
    - Vector-Borne Zoonotic Disease: Diseases that are transmitted to humans via a vector and originate from animal hosts. Examples include Lyme disease (from ticks) and West Nile virus (from mosquitoes).

Life Cycles of Vectors and Zoonotic Pathogens

• The life cycles of vector-borne diseases often involve multiple stages:
    - Egg: The initial life stage where the vector reproductive process begins.
    - Larvae: The stage following the egg, where the organism is primarily aquatic and feeds to grow.
    - Pupae: The transitional stage where the larvae metamorphose into adult form.
    - Adult: The reproductive stage of the insect or vector, capable of transmitting the disease.
    - Example: The adult mosquito emerges from the pupa and is capable of transmitting pathogens to new hosts.