Infection Transmission Flashcards
Transmission Outline
How an organism moves from 1 successfully infected host to a new host. Dependent on factors: virulence of pathogen (dead host less likely to transfer), no. of microbes shed (more microbes = greater chance of infection), microorganism’s survival chances, efficacy of infection (conc of pathogen needed to infect new host) and susceptibility of host (antibiotics feom previous infection)
Factors that influence a microorganism’s survival in enviorment
UV resistance and spore formation (prevent drying, enveloped tend to try out faster, only gram positive produce spores). Microorganisms susceptible to drying need constant close contact with water
Routes of Transmission
Respiratory/oral spread, fecal-oral spread, venereal/blood spread, vector spread, vector-vertebrate spread, vertebrate resevoir spread and innoculation spread
Transmissions From Respiratory Tract Outline
Infection stimulates excess mucus production aiming to remove pathogen from body. Pathogen is removed from body in mucus and droplets via sneezing (larger amount of particles)/coughing. Droplets of different sizes travel different distances (smaller = further) and carry different microbes. Most likely to accour in humid, poorly ventilated, overcrowded areas
Range and pathogen eg for large drops
~ 4m. Eg mycobacterium tuberculosis
Range and pathogen eg for small droplets
Small droplets linger in the air indefinitely. Eg measles virus
Why are some microorganisms not able to replicate in host despite making contact
Regions of body may not be suitable for survival/proliferation. Eg Rhinovirus can’t survive/reproduce in lower respiratory tract (too warm), it has to reach upper respiratory tract (cooler)
Preventing spread of RTIs
Appropriate PPE in community and clinical settings (eg community mask over mouth and nose), vaccination, regulated distance and isolation
Appropriate PPE to prevent RTIs Clinically
Masks: PRF95 and P2+ (duck bill masks)
Fecal-Oral Route Outline
Ingestion of food/water contaminated by fecal particles (by water-sewage mix, insects and poor hand hygiene). Diahorrea is immune systems response to remove pathogen
When do antibiotics need to be prescribed for food poisoning
When suffering from enteric fever with salmonella typhi and paratyphi (from eggs and poultry). Otherwise food poisoning is self limiting (administering antibiotics has risk of resistance developing). Ensure patient has water and electrolytes replenished
Non-bacterial Food poisoning
Giardla intestoinalis (parasitic) and Hepatitis A & E (viral)
Fecal-oral route prevention
Good hand hygiene, better sanitation, vaccination and travel advice
Transmissions through blood/secretions (STIs) Outline
Transmitted through mucosal/blood contact. Most microorganisms produce a discharge. Less efficent then faecal-oral and respiratory. Increased in recent years due sex’s greater social acceptance
Examples of STIs
Human Papilloma Virus (HPV 16 & 18, genital warts, anogenital carciroma), Hepatitis B & C and Treponema Palladium (syphillus, damage to feet’s skin)
Blood Borne Diseases Transmission Outline
Transmission through vector(insect)/vertebrae(animal), inoculation (injection) and placental (vertical transmission)
Blood Borne Diseases Examples
Plasmodium falciparum (malaria parasite from mosquito), HIV and Hepatitis B & C
Vertical Transmission Outline
From parent to child via blood (transplacental), sperm, ovum, and milk. Eg HIV, Hepatitis B & C and mumps
Horizontal Transmission Outline
moves from 1 effected individual in a population to another via vectors (surfaces), food, water and air
2 categories of transmission from animals
invertebrates/arthropods and vertebrates (zoonoses)
Invertebrate Transmission
Transmission by bite (mouth), shedding (body) or defecation (intestines). Pathogen either admined directly from insect (eg Zika, zika virus, mosquito, malformed fetus skulls) or from regurgetated blood insect previously ingested (eg plague, yersinis pestistis, flea). Due to climate change there will be a migration of insects
Zoonoses Def
Infection transmitted via animal directly (through bite, shedding, defecation or consumption of their meat) or indirectly (parasite). Epidemiology depends on closeness of animal and human, local customs as to hygiene and food safety.
Epidemiology Def
Study of occurance and distribution of disease and otehr detriments to health in a population. Important to consider for: reemerging and new diseases, globalisation considerations, HAIs prevention and bioterrorism prevention
Sporadic Infections Outline
Infection might emerge once or twice in a population. eg bacterial meningitis
Endemic Infections Outline
Infection emerges consistently in a pop. at low/moderate severity eg rhinovirus. Point of most frequent pop infection = hyperendemic infection (eg Winter)
Outbreak Outline
Sudden and unexprcted infection of a defined population in a defined locale
Epidemic Outline
Outbreak where effected population is spread across different nations
Pandemic Outline
Outline where effected population is global in scale
Morbidity Rate Def
no. of individuals that became ill due to specific disease during a specific time
Morbidity Rate Calculation
(no. of newly infected individuals)/ (total pop)
Prevalence Rate Def
Total no of individuals infected in population without factoring in time. Depends on: incidence rate and no of disease cases
Mortality Rate Def
relatiosnhip between no of disease deaths and size of disease pop
Mortality Rate Calc
(no of disease related deaths)/ (diseased population)
