Week 2 Infectious Disease Epidemiology

What is Epidemiology?

The study and analysis of the incidence, distribution and control of diseases

What is disease epidemiology?

• Deals with one population e.g humans

• Risk is a case

• Identifies causes

• E.g cancer (radiation source)

What is infectious disease epidemiology?

• Two or more populations e.g human and pathogen

• A case is a risk factor

• The cause is often known

Give examples of two or more populations in infectious disease epidemiology

• Humans

• Infectious agents: Helminths, bacteria, fungi, protozoa, viruses, prions

• Vectors: Mosquito (protozoa-malaria), Snails (helminths-schistosomiasis), Blackfly (microfilaria-onchocerciasis)

• Animals: Dogs and sheep/goats : Echinococcus, Mice and Ticks: Borrelia

What is infectious disease epidemiology used for?

• Identification of causes of new, emerging infections, e,g HIV, vCJD, Zika, SARS-CoV2

• Surveillance of infectious disease

• Identification of source of outbreaks

• Studies of routes of transmission and natural history of infections

• Identification of new interventions

What is an infectious disease caused by?

infectious agent

What is communicable diseases caused by?

Transmission directly or indirectly from an infected person

What is a Transmissible disease caused by?

Transmission through unnatural routes from an infected person

Give examples of routes of direct transmission

• Skin-skin: Herpes type 1

• Mucous-mucous: STIs

• Across placenta: toxoplasmosis

• Through breast milk: HIV

• Sneeze-cough: Influenza

Give examples of routes of indirect transmission

Food-borne: salmonella

Water-borne: Hepatitis A

Vector-borne: Malaria

Air-borne: Chickenpox

What are 3 types of modes of disease transmission?

Contact transmission

Vehicle transmission

Vector Transmission