Final exam - Week 4 Flashcards
what is a disease caused by the invasion and growth of pathogenic agents or microbes in a host?
infectious disease
What is infectious disease synonymous with?
communicable disease
true or false: infectious disease is always contagious
false; may or may not be
true or false; IDs are among the leading causes of death
true
What are illnesses capable of transmission directly or indirectly among humans?
contagious
What 3 factors comprise the epidemiological triangle of disease? what additional?
- host
- agent
- environment
- vector - center
What are agent factors associated with?
the pathogen causing the infection
What are host factors associated with?
those internal to the animal or human invaded by the agent that contribute to its susceptibility and infectiousness
What are environmental factors?
are everything else external to the host and agent that influence the transmission and development of an infectious disease
What is a vector?
are organisms, usually invertebrate arthropods like mosquitoes and ticks, that transmits a agent from one host to another
Host factors that contribute to infectious disease transmission include what?
those that effect host susceptibility as well as those that relate to the host infectiousness
What does susceptibility include?
both host resistance and immunity
What role has genome scanning had in ID?
they have been able to identify genes associated with specific infectious diseases.
What factors are under resistance for susceptibility?
- Genetics
- Age/ gender/ancestry
- Pregnancy
- General health
- Nutrition
- Chronic diseases
- Stress
what is an innate resistance to a specific antigen or toxin, such as through genetics which we just discussed?
natural immunity
What does acquired immunity come from?
from actual exposure to a specific infectious agent and is further divided into two subcategories, active and passive.
When does active immunity occur?
occurs when the host stimulates its own antibodies thru exposure to the agent, either through natural exposure or exposure with an immunization
When does passive immunity occur?
when antibodies are transferred to the host, either through mother to infant or through immune globulin or antitoxin.
what is the resistance of a population to the infection because a high proportion of individual members are resistant?
herd immunity
What 2 things can herd immunity be?
- natural due to genetics
2. acquired from past exposure
What do immunizations provide?
active immunity for the individual and herd immunity for the community.
What is the ability of an infected host to transmit infection?
infectiousness
What is the infected host usually referred to as?
as the human or animal reservoir for the infectious agent
What are the 3 stages of infection?
- latent
- communicable
- incubation
What is the latent stage of infection?
begins with exposure and ends when the pathogen begins to shed.
Are people infectious during the latent stage of infection?
no
What is the communicable stage characterized by?
the shedding of the pathogen
what is the progression of the communicable stage?
begins before symptoms and ends after symptoms disappear
Is a host infectious during the communicable stage?
yes
Only what type of disease has a period of communicability?
contagious disease
When does the incubation stage begin and end?
begins with exposure to the agent like the late stage and ends when symptoms appear
When is a host frequently infectious?
when they are asymptomatic
For diseases like tetanus and Lyme disease, which are not infectious, what is unique about them?
they have an incubation and disease period, but latent and communicability periods do not apply
What are organisms capable of producing infection in a host?
infectious agents
What are the 4 infectious agents?
- bacteria
- viruses
- parasites
- fungi
What are the 3 ways an agent interacts with its host?
- infectivity
- pathogenicity
- virulence
What is infectivity?
refers to the ability of an agent to enter, survive and multiply in a host or their power to invade and infect large numbers of people.
What is infectivity a characteristic of? infectiousnessness?
a. agent
b. host
What is the agents ability to cause disease and refers to the proportion of infected people who actually develop the disease?
pathogenicity
Infectious agents that cause a large percentage of subclinical infections are said to have what?
low pathogenicity
What is the ability to produce a severe pathological reaction and refers to the proportion of infected people who died or become severely disability?
virulence
How is the virulence of a disease often measured?
in terms of mortality rate
What are the environmental factors in the epidemic triangle?
all those that are external to the animal or human host and the agent
What can environmental factors be?
- physical
- biological
- social
- cultural
What are examples of environmental factors that can impact infectious disease?
- Location (institutions, geography, spectrum of disease)
- Non-living reservoirs (soil, water)
- Climate change and extremes
- Insects and animals
- Body fluids
- Crowding, education, resources and access to care
- Norms, health beliefs, health behaviors
What is an endemic?
occurring at a consistent, expected level in a defined and often limited area geographic area
What is an outbreak?
unexpected occurrence or increase; limited geographical area; limited period of time.
What is an epidemic?
unexpected occurrence or increase; in a defined but larger geographical area; extended period of time
What is a pandemic?
epidemic that has spread over several countries or continents, usually affecting a large number of people.
What is the means by which an agent is transmitted from one host or inanimate reservoir to a host?
modes of transmission
What are modes of transmission impacted by?
- host
- agent
- environmental factors
What is vertical transmission?
the passing of the infection from parent to offspring via sperm, placenta, milk, or contact in the vaginal canal at birth
What is horizontal transmission?
the spreading of infection from a host or reservoir to a person and includes direct, indirect, airborne and vector transmission
true or false; horizontal transmission is limited to contagious diseases.
false; it is not
How do direct transmissions occur?
by immediate transfer of pathogen from an infectious host to a susceptible host.
What does direct transmission include?
includes touching, sexual intercourse, kissing,, biting.
When does indirect transmission occur?
occurs when the infectious agent is transported via contaminated inanimate reservoirs such as air, water, door knobs, counters, eating and drinking utensil, personal care products and medical supplies such as shares.
How does direct transmission occur?
occurs by immediate transfer of pathogen from an infectious host to a susceptible host and includes touching, sexual intercourse, kissing,, biting.
Can droplet be vertical and horizontal?
yes, but is usually horizontal
When does indirect transmission occur?
occurs when the infectious agent is transported via contaminated inanimate reservoirs such as air, water, food, door knobs, counters, eating and drinking utensil , personal care products and medical supplies such as sharps
What is a type of indirect transmission which occurs through droplet nuclei or dust particles?
airborne transmission
How is airborne different from droplets?
much smaller and can travel farther and also remain suspended for long periods before they are inhaled by a host
What are vectors?
are organism, usually invertebrate arthropods like mosquitoes and ticks, that transmits a pathogen from an infectious to susceptible host.
How can infectious diseases which are not contagious be transmitted?
direct or indirect mode of transmission.
What are 4 major public health problems?
- TB
- valley fever
- malaria
- rabies
What are the two types of TB conditions?
- latent TB infection
2. active TB infection
What are people with latent TB?
they are infected with the bacteria and do not have symptoms
What is the agent of TB?
- A bacteria - mycobacterium tuberculosis
2. MDR TB and XDR TB
Finish the sentence: people with latent TB are hosts during the…
latent period of infectiousness and are not contagious
What are host factors associated with increased risk of TB?
Genomics, race and age can impact risk for infection.
What is the most significant host factor for TB disease?
positive HIV status, although all people with weakened immune system are at increased risk
What are environmental risk factors for TB?
Living/working in a congregate living conditions; refugee camps; working with high risk populations; living/traveling in countries with high TB rates; close contract with someone who has TB disease
How is TB spread? Not spread?
spread by droplets nuclei, not saliva
What is the primary strategy used in the prevention and control of TB?
early detection and treatment of latent TB in at risk populations and health care workers
How is screening usually done for TB?
skin test or blood test
How is TB disease treated?
taking several different drugs for 6 to 9 months
What is the most effective strategy to treat for TB disease?
Directly observed therapy or DOT
What is DOT or eDOT?
Patient takes the medicine while the health care worker watches. Many health department are now using eDOT, which is using technology to monitor adherence to ingesting the prescribed medication either in real time or recorded.
What are other important health care facility strategies for TB control?
special masks for HCWs which filter out the tiny droplet nuclei that are frequently pretty dense in the TB patients room; having TB patients use a mask; and caring for TB patients in reverse isolation rooms to reduce the amount of TB in the area.
true or false; the TB vaccine is used a lot in the US
false
When should the TB vaccine be used?
should be considered for only very select people who meet specific criteria
What is coccidiodymosis?
valley fever; a respiratory infection caused by the inhalation of fungal spores that live in soil and which have become airborne, usually due to wind, soil disturbance and recreational activity.
Is there a vaccine available for cocci or valley fever?
no
What is cocci highly?
highly infective
What is there low of in cocci or valley fever?
low pathogenicity and virulence
Is susceptibility to cocci universal?
yes
Who is more at risk than the general population for cocci?
older adults
Who is the population at risk for the more severe form?
- Filipino ancestry
- black race
- hispanics
- native Americans
Who else is at risk for cocci?
People who are immuno-compromised due to HIV, organ transplants, Hodgkin’s disease, diabetes, or chronic corticosteroid therapy
Is pregnancy a significant risk for cocci?
yes
People who recover from cocci have what?
lifelong active immunity
Where is cocci an endemic?
southwestern US
What kind of human behavior puts people at risk for cocci?
People who work or play at stirring up the soil, as in construction, excavation, farming, gardening and driving ATVs are at increased risk for infection.
true or false; cocci is seasonal
true; most infections occur during hot dry weather following a rainy season
is it easy to intervene in cocci?
no; it is hard to intervene during the susceptible stage and early subclinical stages of the disease
Is there a vaccine or cure for cocci?
no
what is the transmission of cocci?
airborne
what is the public health approach to cocci?
awareness to promote earlier diagnosis
is there person to person or animal to person transmission in cocci?
no
What is the agent of malaria?
4 species of plasmodium parasite
How is malaria transmitted?
by the bite of an infected female anopheles mosquito
What are host factors that make someone more susceptible to malaria?
- Genetic factors-SCT, thalassemias
2. Pregnancy
What is airport malaria?
malaria caused by infected mosquitoes that are transported by aircraft from a malaria-endemic country to a non-endemic country.
What type of pathogens are plasmodium parasite?
virulent pathogens
what do Public health strategies for Malaria in the US focus on?
- Primary Prevention measures, such as prophylactic medications, mosquito repellent and bed nets.
- late Secondary Prevention activities to detect malaria earlier through recognition of symptoms.
What are the highest risk US communities for malaria?
1st and second generation immigrants
What is the agent for rabies?
rabies virus
Rabies has the highest what?
Rabies has the highest case fatality rate of any known human infection
What are factors that make a host susceptible to rabies?
all humans
Who are the primary hosts of rabies?
mammals
What is the most common mode of rabies virus transmission?
is through the bite, scratch, and contact with the virus-containing saliva of an infected animal.
How can someone have a non-bite exposure?
are rare but possible through transfusions and scratches, abrasions, and mucous membrane contamination with saliva from rapid animals.
Is rabies considered contagious?
no
What are public health strategies to prevent rabies?
- campaigns to increase pet vaccinations
- teaching people, especially children how to avoid bites and as well as the importance to seeking immediate medical attention for any possible exposures.
What are 3 treatment options for rabies?
- wound care
- human rabies immune globulin
- vaccine.
What does immune globulin provide for rabies?
passive immunity
What does the vaccine provide for rabies?
active immunity
What are the 3 ways to control infectious diseases?
- isolation
- quarantine
- social distancing
What does isolation refer to?
separating a sick and infectious host from others for the estimated communicable stage
What stage does isolation apply to?
communicable stage
What does quarantine refer to?
Those not sick but who have been exposed and are possibly infected and contagious
What stage does quarantine apply to?
incubation stage
Can both isolation and quarantine be voluntary or enforced and both states and the federal government have the authority to legally enforce them?
yes
What is social distancing?
a category of population-based public health interventions which aims to increase the space between people and decrease the frequency of contact among people in order to diminish the risk of transmission.
What are examples of social distancing?
- School and work closures
- Travel restrictions and border control
- Mass gathering restrictions
What does social distancing ultimately do?
controls behavior of both potentially contagious and susceptible hosts?
what is the reduction to zero (or a very low defined target rate) of new cases in a defined geographical area?
elimination
What is the irreversible termination of all transmission of infection by extermination of the infectious agents worldwide?
eradication
What is the only disease to ever be fully eradicated in the US?
smallpox
What is the agent of polio?
poliovirus
Has polio been eradicated?
no, only eliminated in the Western Hemisphere and in Europe.
What is polio?
a highly infective virus which invades the nervous system potentially causing paralysis and death.
How is polio transmitted?
primarily through the oral-fecal route and sometimes through contact with saliva.
Can people have long term complications from polio?
Children under 5 are most at risk for paralysis and death.
Where is polio an endemic?
Afghanistan, Nigeria and Pakistan
What is the agent of Dracunculiasis or guinea worm disease?
Dracunculus medinensis (parasite)
How is guinea worm disease transmitted?
Indirect-contaminated water
is there a cure for guinea worm disease?
no
Has guinea worm disease been eliminated?
yes
What is the public health strategy for eradicating GWD?
preventing transmission of the parasite by providing clean water to all communities in at risk countries.
In 2019, GWD was limited to what?
Angola Chad, and Southern Sudan
What is the agent of smallpox?
variola virus
Has smallpox been eradicated?
yes since 1979
How does smallpox present?
characteristic and disfiguring skin eruptions
Is the vaccine for smallpox avialable?
Vaccine no longer available to general public; gov’t maintains supply
Who is the host of smallpox?
humans
How is smallpox transmitted?>
direct via droplets
Where is smallpox now?
in laboratories
What are the 17 routine vaccines available?
Chickenpox (Varicella) Diphtheria Flu (Influenza) Hepatitis A Hepatitis B Hib (Haemophilus influenzae type b) HPV (Human Papillomavirus) Measles Meningococcal Mumps Pneumococcal Polio (Poliomyelitis) Rotavirus Rubella (German Measles) Shingles (Herpes Zoster) Tetanus (Lockjaw) Whooping Cough (Pertussis )
What are the 7 non-routine vaccines available?
Adenovirus Anthrax Cholera Japanese Encephalitis (JE) Rabies Smallpox Tuberculosis Typhoid Fever Yellow Fever
How does public health use some of the reports for disease?
Interrupts transmission Location/treatment of contacts Identifies outbreaks Alerts providers Monitors disease trends Identifies high risk groups Priorities in resource allocation Policy and program development
Who mandates reporting of infectious diseases?
state
What is violation of reporting rules?
a class III misdemeanor and is subject to being reported to the facility’s licensing agency or provider’s state licensing board.
Where are notifiable or reportable diseases reported?
- HCPs report to county health departments
- County health departments report to AZDHS
- AZDHS reports to CDC
Where can you find the notifiable disease lists on a national level?
from CDC website
Where can you find the notifiable disease lists on a state level?
Arizona Department of Health Services
