communicable diseases (422 E3) Flashcards
infectious diseases
when living organisms enter the body and cause disease
communicable diseases
when they can be transmitted from one person/nonhuman to another
what is the relationship between communicable diseases and infectious diseases
all communicable diseases are infectious but not all infectious diseases are communicable
ex: lyme disease is an infectious disease but once a person has lyme disease they cannot pass it on
Communicable Diseases and Pandemics Throughout History: the 1900s
1918-Present:
+Influenza (1918-pandemic but still present today)
this period had new vaccines, abx, & inc in sanitation
1980’s-Present
- HIV/AIDS
- Increase in antibiotic resistance
- Causal connections between infectious organisms and chronic disease
1990’s-Present:
+Food supply concerns (ex. improperly cooked beef and unpasteurized apple juice)
+1993: Hantavirus Pulmonary Syndrome (in southwest)
+1996: Bovine spongiform encephalopathy (BCE) aka “Mad Cow Disease” caused Variant Creutzfeldt-Jakob disease (vCJD) in humans
+1997: Vancomycin-resistant Staphylococcus aureus (VRSA) first reported.
+1997: First case of H5N1 (avian influenza)
+1999: First case of West Nile Virus occurred
2000’s-Present:
+Viral hemorrhagic fevers (VHFs): Ebola and +Marburg (largest outbreak started in 2014)
+Severe acute respiratory syndrome (SARS): “Select Agent”
examples of connections between infectious organisms and chronic disease
h.pylori leading to peptic ulcer disease
select agent
it is a bacterium, virus or toxin that has the potential to pose a severe threat to public health and safety
Communicable Diseases and Pandemics Throughout History: the 2000s
2000’s-Present:
+Viral hemorrhagic fevers (VHFs): Ebola and +Marburg (largest outbreak started in 2014)
+Severe acute respiratory syndrome (SARS): “Select Agent”
+Continuation of food borne illnesses with E-coli in green chiles and raw cookie dough and +Salmonella in peanut butter and Listeria in cantaloupes
+H1N1 (new strain of influenza) started in 2009
+MERS-CoV
+Zika
+COVID-19
factors influencing new infectious diseases
-societal events: economics, impoverishments, is the country war torn, population growth & migration, urban decay -> can make new breading grounds for IDs
-health care: new medical devices, organ tissue transplants ; immunosuppressive drugs, wide spread abx use
-food production: globalization, process & packaging of our food, use of childcare facilities
-human behavior: sexual, drug use, travel diet, outdoor recreation
-environmental: deforestation or reforestation, changes in the waters ecosystems, flood/drought/famine, global warming
-public health: prevention program
-microbial adaptation: changes in virulence and toxic production
types of agents
bacteria: single celled organisms that can reproduce by themselves
virus: have a core of genetic material but it is unable to reproduce on its own
fungus: multicellular microbes that reproduce via spores
parasite: organisms that live off of a host and survive at the expense of a host
characteristics of an agent: Infectivity
the agent’s ability to enter the host organism & multiply
characteristics of an agent: Invasiveness
the agent’s ability to spread throughout the host organism
characteristics of an agent: Pathogenicity
ability to cause disease in the host
characteristics of an agent: virulence
a measure of the severity of disease caused by the agent
characteristics of an agent: toxigenicity
ability to produce damaging poison (toxin)
characteristics of an agent: antigenicity
ability to stimulate an immune response in the host
when thinking about the host, we need to consider
1) exposure
2) host susceptibility
3) host response (to the agent)
when thinking about the environment, we need to consider
1) physical environment: geology and climate
2) biological environment: population density, flora and psychosocial
3) psychosocial environment : occupation of the host
reservior
associated concept to the epi triangle
where an agent generally survives and multiples
+inanimate: water, soil, food, etc
+animate: human (sx or non sx carriers ), non human (animal)
examples of a reservoir: internal
E.coli in the human colon
examples of a reservoir: external
mosquito - borne illnesses in standing water
direct transmission
Immediate transfer of agent from one human to another
- Limited to distance of 3 feet or less
types of direct transmission
Contact Transmission: Direct transfer with very close contact (ex. STI’s, athletes foot)
Droplet Transmission: Expelled large droplets from one person and picked up by another (ex. flu, RSV, diphtheria)
indirect transmissions
Transferred at >3 feet
types of indirect transmission
Vehicle-borne indirect transmission: Animate objects (healthcare work spreading one disease to another room), Inanimate objects (aka fomites; shared toys, shopping carts) & Food or liquid
Vector-borne indirect transmission: usually arthropods (invertebrates)
Airborne transmission: Expelled small droplets through things like cough, sneeze, singing, etc. (ex. TB, COVID, chicken pox, common cold)
patterns of transmission
Unidirectional: nonhuman to human
vertical: parent to child during fetal development, birth, or breast feeding
endogenous: internal source that is asym until something triggers it
bidirectional: nonhuman to human to nonhuman
horizontal: person to person
exogenous: external source
latent period
Period between when an infectious agent enters a host, finds conditions favorable and replicates before shedding
incubation period
Period between invasion of an agent until symptoms appear
communicability period
Period of time the person can infect others (contagious)
transmissibility
Estimations of the basic reproductive number
“if i get infected, how many people can I affect in a certain time period”
portals of entry
Mucous membranes-Syphilis
Respiratory tract-Flu, common cold
Skin-Hookworm
Blood vessels-HIV, Hepatitis B
Placenta-HIV, Hepatitis B
portals of exit
Intestinal tract-Feces (Cholera)
Respiratory tract-Coughing, singing, speaking (COVID-19, TB)
Skin-Scabies lesions
Blood-Hepatitis B
Semen and vaginal fluids-STIs
Wound exudate-MRSA
focus of PH: prevention
reduce or eliminate exposure or susceptibility to a disease
focus of PH: control
reduce incidence or prevalence of a disease at one point in time
focus of PH: elimination
control of a disease within a specific geographical area
focus of PH: eradication
reduce incidence worldwide to zero
surveillance
Refers to an ongoing systematic collection, analysis, and interpretation of health data
The purpose is to detect, monitor, and control the spread of communicable diseases
isolation
Individual-level
Generally, for communicable diseases
quarantine
Population-level:
Used across spectrum from communicable diseases to natural or chemical disasters, etc.
3 levels:
-Shelter in place
-Targeted restrictions on movement and activities
-Compulsory widespread restriction of movements and activities
