Infectious Diseases- the basics Flashcards
describe the 4 parts of the circle of disease transmission
- entry
- replication
- exit
- environmental persistence
at what point in the circle of disease transmission does spread occur?
exit
how does infection occur in entry through the respiratory tract?
through inhalation of infectious agents
what protective mechanisms does the respiratory tract have against infectious agents? (3)
- mucous from goblet cells
- cilia in epithelium
- specific (IgA) and nonspecific (macrophage and neutrophil) immune defenses
what type of barrier is the mucous secreted by goblet cells in the respiratory tract?
physical barrier
how do cilia in the epithelium of the respiratory tract protect against disease?
do the wave! move bad shit away
what does IgA stand for? what is it produced by?
immunoglobulin Type A, produced by lymphocytes
list 3 factors that help facilitate spread of disease through the respiratory route?
- concurrent infections
- aerosols
- poor ventilation and irritants
describe concurrent infections as a factor facilitating spread of disease through the respiratory route
some microbes stop cilia movement so other microbes can become more pathogenic, basically microbes work together to take you down
describe aerosols as a factor facilitating spread of disease through the respiratory route
sneezing in close proximity = bad news bears
give an example of poor ventilation as a factor facilitating spread of disease through the respiratory route
in pig farms poor ventilation leads to a build up ammonia, which irritates mucosa and leads to more infection
describe transmission of disease through the gastrointestinal tract (2)
- transmission via ingestion of pathogens
2. contamination of feed
list 4 protective mechanisms of the GI tract to prevent disease transmission through this route
- peritalsis: stay right the fuck there
- low pH, bile, secretions: i kill you
- mucus layer: physical barrier
- IgA and non-specific immune defenses
what are 4 factors facilitating spread of disease through the GI tract?
- high contamination of environment
- poor cleaning
- dysbiosis: change in microbiome
- high density of animals
how do pathogens enter through the skin route?
enter through the barrier
what are the protective mechanisms of skin against disease? (2)
- cornified (keratinized) epithelium)
2. skin microbiome
what are the factors facilitating spread of disease through the skin route? (3)
- skin abrasion/rupture/barrier break
- wounds
- animal/insect bites
what are the 3 mechanisms of entry through the reproductive tract for infectious diseases?
- sexually transmitted diseases
- natural mating
- AI!!!!!
what are the 3 protective mechanisms of the reproductive tract against infectious diseases?
- mucous
- innate and acquired immunity
- microbiota
what are the 4 factors facilitating disease transmission through the reproductive route?
- AI is a great way to get em sick if you dont follow proper sanitation protocol
- conjunctive: diseased male
- placenta: vertical transmission of mom to fetus
- horizontal transmission: individual to individual
what are the 9 steps of microbial infection
- acquire access to portal of entry
- encounter “targets” in mucosa
- colonize targets to sustain and/or amplify the encounter
- spread locally in EC matrix to encounter and colonize new populations of target cells
- enter blood and/or lymphatic cells
6-8 (yay): spread to regional lymphnodes and/or then systematically within the circulatory system to encounter, colonize, and invade new populations of target cells that are unique to a specific organ system - cause dysfunction and/or lysis of target cells and disease
what is incubation period?
the time between entry of the pathogen and the development of clinical signs
how long can an incubation period be?
from 24-30 hours up to years
why is there an incubation period?
an organism needs to replicate inside a host enough to be able to cause damage
describe lentiviruses in terms of incubation period
reproduce very slowly and fight with the host immune system constantly in waves
describe the general incubation period for pathogens that cause immunodeficiencies
years
why is knowledge of incubation period useful? (2)
- helps establish quarantine guidelines
2. helps backtrack contacts (contact tracing)
what is infectivity period?
the period of time that an animal is contagious to others