Micro Unit 9 Transmission and Reservoirs

3 types of reservoirs - human

Actively carry virus or microbe (infection) and carriers (no outward signs and symptoms)

3 types of reservoirs - animal

Zoonoses - emerging pathogens come from crossing barrier (only associated with specific species —> now humans are infected)

3 types of reservoirs - environmental (Non living)

Soil, water, food

Transmission

Movement of pathogen to host

3 types of contact transmission - direct

Host comes in contact with pathogen (drank contaminated water or ate contaminated food, stepped on nail)

3 types of contact transmission - indirect

Come in contact with pathogen on surface and picked up infection that way (fomites) contaminated instruments (catheter, IV lines *TB

3 types of contact transmission - droplets

Short distance for transmission (less than 1 meter from someone), cough, sneeze, laugh

Vehicle transmission

Picking up a pathogen through poor food, water, and air (droplets small enough to float to people further away from 1 meter) *legionnaire’s disease, COVID

Vector Transmission

Animals that carry pathogens from one host to another (arthropods) insect has infection and because they bite (biological transmission: different stages or arthropod life cycle means that being bit doesn’t mean you have pathogen *could’ve been infected in egg stage so you need to eats eggs egg to be infected), touch (mechanical: fly walks on food *doesn’t have pathogen only carries it on feet)

Biological vector transmission

Active, arthropod has to bite and transfer pathogen via saliva

Nosocomial Infections

Hospital acquired (pick up in hospital or clinical setting), preventable (2025 750,000 cases)

Factors affecting nosocomial infections

Microbes in hospital environment (much higher amount of microbes in health care facility), compromised (weakened immune system), chain of transmission (pathogen can exist somewhere far away from healthy individual and a series of events can cause the pathogens to be picked up by someone who is otherwise healthy) *usually one of these factors doesn’t ensure you will get a nosocomial infection

Microbes in Hospital Environments

Acinetobcater: cause infection in blood, urinary tract, lungs, or wounds

Clostridium difficile (C.diff): endospores forming

Carbapenum resistant Enterobacteriaceae (E.coli, K.pneumoniae, MRSA)