Micro final

Predisposing factors of disease definition

any factor that would increase a host's ability to be infected of alter how a disease progresses

Predisposing factors of disease examples

gender - UTIs, pneumonia, meningitis

genetics - sickle-cell anemia, malaria

climate - environmental survival of MO

nutrition

fatigue

age

lifestyle

Stages of disease

can be linked to MO growth

-MOs vary in period length

Incubation period, prodromal period, period of illness, period of decline, period of convalescence

Incubation period

initial infection to first symptoms

Prodromal period

early, mild symptoms

relatively short, may not be present in all

Period of Illness

most severe signs and symptoms; major immune response

Period of decline

symptoms decrease; susceptibility to secondary infections (opportunistic)

Period of convalescence

return to normal/homeostasis

Reservoirs

source of a disease-causing MO

3 major groups; humans, animals, nonliving

Reservoirs: Humans

-symptomatic

-asymptomatic (carriers, during incubation or convalescence)

-STIs, streptococcal infections

Reservoirs: Animals

zoonoses

-animals to humans

many different routes

-direct contact with infected animal/feces

-animal contaminated water, food, animal products, hide

-arthropod vectors (tics, lice, mosquitos)

Reservoir animals: Influenza

causative agent = influenzavirus

reservoir = swine, birds

transmission = direct contact

Reservoir animals: Rabies

causative agent = lyssavirus

reservoir = bats, skunks, foxes, dogs

transmission = direct contact

Reservoir animals: Lyme disease

causative agent = borrelia burgdoferi

reservoir = field mice

transmission = tick bites

Reservoir animals: rocky mountain spotted fever

causative agent = rickettsia rickettsii

reservoir = rodents

transmission = tick bites

Reservoir animals: salmonellosis

causative agent = salmonella enterica

reservoir = poultry, reptiles

transmission = food, water, hands in mouth

Reservoir animals: ringworm

causative agent = trichophyton, microsporum

reservoir = domestic animals

transmission = direct contact

Reservoir animals: Malaria

causative agent = plasmodium spp.

reservoir = monkeys

transmission = anopheles mosquito bite

Reservoir animals: toxoplasmosis

causative agent = toxoplasma gondii

reservoir = cats and other animals

transmission = meat, direct contact with tissue/feces

Reservoir animals: tapeworm

causative agent = taenia solium

reservoir = pigs

transmission = undercooked contaminated pork

Reservoirs: nonliving

environmental:

soil - fungi, nematodes, clostridium tetani, C. botulinum

water - protozoa, some helmiths

food - food poisoning; salmonellosis

Transmission

contact, vehicles, vectors

Transmission: contact

direct

-btwn source and host

-common cold, influenza, hep A, measles, STIs

-prevent via PPE

indirect

-btwn host and nonliving

-HIV/hep B

-prevent via clean equipment

droplet

-btwn aerosolized liquid and host

-influenza, whooping cough

-prevent via good hygiene

Transmission: vehicle

from a medium

water

-fecal contaminations - cholera/leptospirosis

food

-poor cooking, storage or prep

-poisoning or tapeworms

air

-like droplet but larger distance

-airborne/dust particles

-TB/fungal infections

Transmission: vector

by another organism

mechanical

-passive = insect from vectors body to food

-typhoid fever / shingellosis on fly feet

biological

-more active and complex

-some phase of MO life cycle (growth/reproduction)

-malaria - plasmodium falciparum