The ability to enter and multiply in the host.

The ability to produce a specific clinical reaction after infection occurs.

The ability to produce a severe pathological reaction.

Types of human reservoir

Plants

Soil

Water

Sexually transmitted diseases Syphillis Gonorrhea, Chlamydia HIV Urine. Schistosmiasis leptospirosis

Mount - through bites e.g. rabies Referred to as enteric diseases Controlled through food hygiene, sanitary sewage disposal. e.g. Hepatitis A Salmonella sp (include Typhoid) Shigella Cholera Giardia Compylobacter

Through superficial lesions Superficial skin lesions that produce infectious discharges are found in smallpox, varicella (chickenpox), syphilis, chancroid, impetigo. • Percutaneous exit occurs through mosquito bites (malaria, West Nile virus) or through the use of needles ( hepatitis B and C, HIV)

Mother to fetus transmission of rubella, HIV, syphilis, and cytomegalovirus Can cause congenital anomalies

Involve vectors

Vector-borne

When disease agents are spread by environmental, vehicles or by air. Anything may be a vehicle, including objects, food, water, milk, or biological products. e.g. Food is a common vehicle for salmonella infections Water is the usual vehicle in cholera outbreaks Surgical instruments and implanted medical devices may be the vehicles of staphylococcal infections

Airborne

Food-borne

Water-borne

Objects e.g. surgical instrument

Acquired by experiencing an infection, 1. “active natural immunity.” immunity after a single infection, but many others do not. A single bout of measles or chickenpox, for example, confers lifelong immunity. 2. “passive natural immunity,” - the transfer of antibodies from the mother to the newborn child, via the placenta and/or breast milk. This is diminishes after varying lengths of time.

a. Active Natural immunity

b. Passive Natural immunity

vaccine

Toxoid

Immuno-globulin