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