Micro Test 2 CH. 9
Population
Any defined group of people
Malaria affects 300-500 million people per year, making it one of the most common infectious diseases in the world. It is spread through the bite of the Anopheles mosqito. What mode of transmission is responsible for the spread of this disease? A. direct contact B. vector C. indirect contact D. vehicle transmission
B The Anopheles mosquito is an arthropod that transmits the parasitic protozoan Plasmodium. This type of transmission is vector-borne, in this case due to the bite of a mosquito.
From the list below, choose a biological vector A. food B. flea C. housefly D. fomite E. respiratory droplet
B When a portion of the infectious disease cycle exists in the organism/vector, and the vector is not merely a physical transporting mechanism, then the organism is a biological vector.
Zoonotic disease falls into which category of direct contact transmission? A. Person to person B. Animal C. Environmental D. Vertical
B Zoonotic disease is disease that is transmitted from animals to people.
Direct Mode of Transmission: Animal
Bite (rabies) or scratch (cat-scratch fever) Zoonotic diseases
Neisseria meningitidis, the causative agent of meningococcal meningitis, often resides benignly in the respiratory tract of an infected carrier. When the organism crosses the blood-brain barrier, however, a dangerous form of meningitis results. What best describes an organism that is harmless in its normal habitat but virulent in another? A. Commensal microbe B. Parasitic microbe C. Opportunistic pathogen D. Antagonist
C
Which of the following statements could be used to explain term "latent disease"? A. This disease develops rapidly but lasts a short time B. This disease develops slowly and continues for a long period C. Agent causing the disease remains inactive for a time, but once become active it rapidly develops the diseases D. This disease is constantly present in a population
C
Noncommunicable Disease
Caused by infectious agents that normally grow outside the human body and are not spread from one host to another Don't spread from person to person Ex) Tetanus
Vector Control
Controlling arthropod vectors helps prevent the spread of many dangerous infectious diseases caused by bacteria, viruses and parasites Ex) Ticks and mosquitoes
Virulence
Degree of pathogenicity of the infectious agent Ex) Severity of the damage that is caused to a host by a microbe
Epidemiological Triangle: Endogenous Example
Dental Carries Host Factors: Tooth enamel, saliva, Immunity Agent Factors: Bacterial biofilm, specific bacteria Environmental Factors: Plaque, enzymes, minerals, community norms
Epidemiology Includes:
Disease symptoms, etiological agent, reservoir, transmission patterns, incubation period, risk factors, potential complications, treatments and prevention
True Pathogens
Do not require a weakened host to cause disease Can effect anyone -- healthy or not
Stages of Infectious Disease: Prodromal Phase
Early symptoms develop Ex) Sneezing, stomach ache, etc Nonspecific symptoms
Centers for Disease Control and Prevention
Federal public health agency that falls under the US Department of Health and Human Service (HHS) Serves as central source of epidemiological information CDC establishes and oversees surveillance networks designed to help prevent disease by enabling earlier detection of outbreaks
Epidemiological Triangle: Exogenous Example
Food Poisoning (Salmonellosis) Host Factors: Person Agent Factors: Salmonella Environmental Factors: Chicken was undercooked
Direct Mode of Transmission: Vertical
From mother to child Ex) In utero: HIV, syphilis to child - Vaginal delivery - Breast milk: HIV
Pathogenicity
General ability of an infectious agent to cause disease in a host Ex) Potential to cause harm
Reservoir
Habitat Includes: humans, animals, substance or the environment
Duration
How long infection lasts
Emerging Pathogens
Include newly identified agents as well as pathogens that previously caused only sporadic disease Ex) Zika
HAIs (Nosocomial)
Infections that patients get while receiving treatment for other medical or surgical conditions
Pathogens
Infectious agents that can cause disease Classified into 3 major groups: 1. Prokaryotic (bacteria) 2. Eukaryotic (fungi, helminths, protozoa 3. Acellular (viruses, prions)
Sporadic Disease
Isolated infections in a particular population Occasional occurence Ex) Ebola
Also nationally coordinated surveillance systems for
Monitoring Antibiotic resistance HAIs Food-borne illnesses Bioterrorism
Epidemiology
Monitoring and controlling disease occurrence to promote public health Studies patterns of disease incidence to design measures to limit infection transmission
Prevalence
Morbidity in a given population during a specified time Indicates how widespread the disease is
National Notifiable Diseases Surveillance System (NNDSS)
Network of local hospitals and private healthcare providers Monitor and report certain diseases Diseases on a state or local tracking list are called reportable diseases
Mortality Rate
Number of deaths in a specific population during a specific time (death rate)
Incidence rate
Number of new cases in a defined population during a defined time frame Indicates risk of contracting a disease
Pandemic
Occurs if an epidemic spreads to numerous countries, continents or is worldwide Ex) HIV
Opportunistic Pathogens
Only cause disease when they take advantage of opportunity not usually available; Host is weakened or a protective barrier is breached Ex) immunocompromised, injury, etc)
Source
Origin from where the individual acquires infection May or may not be the same as the reservoir
Indirect Mode of Transmission: Airborne
Particles carry pathogens Ex) Respiratory aerosols - measles, tuberculosis - Windborne: Histoplasmosis - Animal waste: Hanta virus
Indirect Mode of Transmission: Vector (Biologic)
Passive transport of the pathogen on the body of an insect Pathogen has part of its life cycle in an insect Ex) Mosquito Bite: Malaria, yellow fever, zika - Tick Bite: Lymes disease - Flea Bite: Plague
Endogenous Sources
Pathogen came from inside the host's own body Misplaced normal biota: Harmless bacteria enters incisions to cause postoperative infections Disrupted Microbiota/Opportunistic Pathogens: Yeast in vagina or bacteria in gut can cause infections after antibiotics
Indirect Mode of Transmission: Vehicle
Pathogen introduced to the host through contact with contaminated objects (FOMITES) Ex) Foodborne: Salmonellosis - Contaminated needles: HIV, hepatitus - Contaminated water: Cholera
Exogenous Sources
Pathogen is external to the host Environmental: Contaminated food, medical equipment, soil or water Animals: Transmit zoonotic diseases to people Humans: Transmit communicable infections from one person to another
Direct Mode of Transmission: Environment
Pathogen resides in an environmental source Ex) Swimmer's Ear - Soil: Bacillus Anthracis in soil enters cut
Stages of Infectious Disease: Sequelae
Pathogen/disease is gone but there is permanent damage
Stages of Infectious Disease: Convalescent Phase
Patient recovers In some cases, the pathogen is kept latent in patient
Latent/Subclinical/Asymptomatic Infections
Patients experience no or minimal signs or symptoms to indicate infection (but can still be contagious) Ex) Sexually Transmitted Infection
Active/Symptomatic Infections
Patients have signs and symptoms of the disease Sign: Can be measured; a fever or a rash Symptom: Nonspecific and can't be seen; "doesn't feel well"
Quarantine
Period of confinement away from the general population to control the spread of disease
Direct Mode of Transmission: Person to Person
Physical contact between the source and susceptible host Skin or mucous membrane contact Directly contacting bodily fluids or excrement Ex) Saliva, touching, sex
Acute Disease
Rapid onset and progression
Epidemic
Rapid, widespread disease outbreak in a particular region during a relatively short time frame Ex) Cholera, Influenza
Stages of Infectious Disease: Period of Decline
Replication of the infectious agents is brought under control Symptoms start to resolve Regain good health
Endemic Infections
Routinely and constantly detected in a population or region Ex) Common cold Always there at a low level
Chronic Disease
Slower onset and progression
Zoonotic Disease
Spread from animals to humans Many are noncommunicable (do not spread from person to person) Ex) Rabies
Mortality rate
The incidence/rate of a specific disease within a population
Stages of Infectious Disease: Acute Phase
The peak of the disease Highest pathogen level Specific Symptoms
Stages of Infectious Disease: Incubation Period
The time between infection and the development of the earliest symptoms NO symptoms Low pathogen levels
Eradication
There are no longer any cases of an infectious disease anywhere in the world Only happened once: Smallpox (1977) Costly
Indirect Mode of Transmission: Vector (Mechanical)
Transmission of microbe by a medium such as water, food, or air to susceptible host Pathogen "hitches a ride" but doesn't have part of its life cycle in the a vector Ex) Flies: landing on dog feces and then on food - Cockroaches: Scurrying through trash then food
Communicable diseases
Transmitted directly or indirectly from one host to another Ex) Direct: human to human Indirect: Touching germ infected doorknob
Contagious Disease
Very communicable and capable of spreading easily and rapidly from one host to the next - In the air
Infections acquired as a result of a hospital stay are called ____________ infections.
nosocomial health care associated, HAI, or nosocomial are all correct.
Factors that increase risk of HAIs
- Catheters/indwelling medical device - Surgery - Injections - Health care settings that aren't properly cleaned/disinfected - Overuse/improper use of antibiotics
Best candidates for eradication are:
- Easily identifiable - Treatable - Preventable by vaccination - Human-specific
Disease Prevention
- Frequent hand washing - Avoidance of intravenous drug use - Drink clean water
I just discovered a new pathogen that was comprised solely of a protein that infected the brain. Which group of pathogens would it most likely fit into? A. Prions B. Viruses C. Bacteria D. Fungi E. Protozoans F. Helminths
A
Which of the following is the correct sequence of events in infectious diseases? A. incubation, prodromal period, illness, decline, convalescence B. incubation, decline, prodromal period, illness, convalescence C. prodromal period, incubation, illness, decline, convalescence D. convalescence, prodromal period, incubation, illness, decline
A
Which of the following shows the correct relationship among the epidemiology terms listed? prevalence > incidence > mortality incidence > prevalence > mortality mortality > morbidity > prevalence mortality > incidence > prevalence
A
T. spiralis is acquired when a person eats undercooked meat contaminated with larvae of the worm. Which disease transmissions does this represent? A. Vehicle transmission B. Contact transmission C. Mechanical transmission D. Biological transmission
A The causative agents of disease can be transmitted from the reservoir of infection to a susceptible host by three principal routes: contact, vehicles, and vectors. Contact transmission is the spread of a disease agent by direct contact, indirect contact (via fomites), or droplet transmission. Vehicle transmission is the transmission of disease agents by a medium, such as air, water, or food. Vector transmission uses animals that carry the disease agent from one host to another and mechanical transmission where the disease agent is passed passively, via contact (such as a fly landing on a person's food). Biological transmission is an active process, where the animal forces the disease agent into the new host (such as a bite from a tick).
Which groups play a role in the collection of data to produce the National Notifiable Diseases Surveillance System (NNDSS)? Hospitals Healthcare providers Laboratories State and local public health authorities Centers for Disease Control and Prevention World Health Organization
A, B, C, D, and E All will play a role in data collection, with the exception of the World Health Organization. The NNDSS is a national product, but the NNDSS is often shared to produce world data.
Which of the following is true about Healthcare-Associated Infections (HAIs)? You can have more than one correct answer HAIs are caused by opportunistic microbiota HAIs can be prevented by standard precautions HAIs- causing bacteria may be resistant to antibiotic therapy Invasive procedures increase patients susceptibility to HAIs
A, B, C, and D All the answers are correct. HAIs is caused by opportunistic microbiota in a compromised host. Invasive procedures make patients vulnerable and invasive devices provide a pathway for microorganisms from the environment to enter the patient's body. Pathogens can proliferate on the devices themselves. Transmission of microbes in health care settings could be reduced using standard precautions, like using personal protective equipment and disinfection of patient-care equipment and instruments.
H. capsulatum infections are more likely to occur in people that are classified as a compromised host. Select all the factors that can lead to a compromised host. Broken skin Broken mucous membranes Exposure to microorganisms Suppressed immune system
A, B, and D A compromised host is one whose resistance to infection is impaired by disease, therapy, or burns. Two principal conditions can compromise the host: broken skin or mucous membranes and a suppressed immune system.
Infectivity
Ability of a pathogen to infect a host and the frequency of this event
Infectious Disease
An illness caused by a pathogen <1 % actually cause disease
Reemerging Pathogens
An infectious agent that was under control but is now resurfacing Ex) Whooping cough Often cause epidemics or pandemics