MICRO Day 3 Disease Transmission

A mosquito bites a person who subsequently develops a fever and abdominal rash. What type of transmission would this be? A. mechanical vector transmission B. biological vector transmission C. direct contact transmission D. vehicle transmission

B. biological vector transmission

Biological transmission

Biological transmission occurs when the vector uptakes the agent, usually through a blood meal from an infected animal, replicates and/or develops it, and then regurgitates the pathogen onto or injects it into a susceptible animal. Fleas, ticks, and mosquitoes are common biological vectors of disease.

Which of the following is a pathogen that could not be identified by the original Koch's postulates? A. Staphylococcus aureus B. Pseudomonas aeruginosa C. Human immunodeficiency virus D. Salmonella enterica serovar Typhimurium

C. Human immunodeficiency virus

Which of the following choices lists the steps of pathogenesis in the correct order? A. invasion, infection, adhesion, exposure B. adhesion, exposure, infection, invasion C. exposure, adhesion, invasion, infection D. disease, infection, exposure, invasion

C. exposure, adhesion, invasion, infection

Which is the most common type of biological vector of human disease? A. viruses B. bacteria C. mammals D. arthropods

D. arthropods

Which period is the stage of disease during which the patient begins to present general signs and symptoms? A. convalescence B. incubation C. illness D. prodromal

D. prodromal

Cattle are allowed to pasture in a field that contains the farmhouse well, and the farmer's family becomes ill with a gastrointestinal pathogen after drinking the water. What type of transmission of infectious agents would this be? A. biological vector transmission B. direct contact transmission C. indirect contact transmission D. vehicle transmission

D. vehicle transmission

________________ can be limited by standard/universal precautions, transmission precautions, surgical asepsis, and biosafety level precautions.

HAIs

__________________________________ are costly and often have a poorer prognosis than community acquired infections.

Healthcare associated infections (HAIs, nosocomial)

Healthcare-associated infection (HAI)

Infections can be associated with the devices used in medical procedures, such as catheters or ventilators. These healthcare-associated infections (HAIs) include central line-associated bloodstream infections, catheter-associated urinary tract infections, and ventilator-associated pneumonia

______________________ can be used to identify the etiological agent of certain infectious diseases.

Koch's postulates

The concentration of pathogen needed to kill 50% of an infected group of test animals is the __________.

LD50

Noncommuicable disease

Noncommunicable diseases (NCDs), also known as chronic diseases, tend to be of long duration and are the result of a combination of genetic, physiological, environmental and behaviors factors. The main types of NCDs are cardiovascular diseases (like heart attacks and stroke), cancers, chronic respiratory diseases (such as chronic obstructive pulmonary disease and asthma) and diabetes.

Reservoir

The reservoir (source) is a host which allows the pathogen to live, and possibly grow, and multiply. Humans, animals and the environment can all be reservoirs for microorganisms. Sometimes a person may have a disease but is not symptomatic or ill.

Transmission

The way a microbial organism moves from one host to another.

True or False: Infectious diseases can be contagious during all five of the periods of disease.

True

________________, which are used to measure the body's basic functions, include body temperature (normally 37 °C [98.6 °F]), heart rate (normally 60-100 beats per minute), breathing rate (normally 12-18 breaths per minute), and blood pressure (normally between 90/60 and 120/80 mm Hg).

Vital signs

Pure culture

a culture containing a single kind of microorganism

Nosocomial infection

a disease acquired in a hospital or clinical setting A Hospital-acquired infection also known as a nosocomial infection, is an infection that is acquired in a hospital or other health care facility. To emphasize both hospital and nonhospital settings, it is sometimes instead called a healthcare-associated infection.

Intermediate host

a host in which a parasite goes through some stages of its life cycle before migrating to the definitive host

Koch's postulates

a sequence of experimental steps for directly relating a specific microbe to a specific disease The bacteria must be present in every case of the disease. The bacteria must be isolated from the host with the disease and grown in pure culture. The specific disease must be reproduced when a pure culture of the bacteria is inoculated into a healthy susceptible host.

Communicable

able to be transmitted directly or indirectly from one person to another

Cilia, fimbriae, and pili are all examples of structures used by microbes for __________.

adhesion

Active carrier

an infected individual who can transmit the pathogen to others regardless of whether symptoms are currently present

Asymptomatic carrier

an infected individual who exhibits no signs or symptoms of disease yet is capable of transmitting the pathogen to others

Disease

any condition in which the normal structure or function of the body is damaged or impaired

For a ______________ disease, pathologic changes can occur over longer time spans (e.g., months, years, or a lifetime). For example, chronic gastritis (inflammation of the lining of the stomach) is caused by the gram-negative bacterium Helicobacter pylori. H. pylori is able to colonize the stomach and persist in its highly acidic environment by producing the enzyme urease, which modifies the local acidity, allowing the bacteria to survive indefinitely.[2] Consequently, H. pylori infections can recur indefinitely unless the infection is cleared using antibiotics

chronic

Some infectious diseases are also _________________ , meaning they are capable of being spread from person to person through either direct or indirect mechanisms.

communicable

Some infectious communicable diseases are also considered _______________ diseases, meaning they are easily spread from person to person.

contagious

Droplet transmission

direct contact transmission of a pathogen transferred in sneezed or coughed droplets of mucus that land on the new host within a radius of one meter

Nosocomial

disease acquired in a hospital setting

Iatrogenic

disease caused by or acquired during a medical procedure

Subclinical

disease that does not present any signs or symptoms

Biological vector

disease-carrying organism, such as a rat, mosquito, or fly, that spreads infectious disease

Contagious

easily spread from person to person

Which of the following would be a sign of an infection? muscle aches headache fever nausea

fever

A(n) __________ infection is a small region of infection from which a pathogen may move to another part of the body to establish a second infection.

focal

Which of the following is an example of a noncommunicable infectious disease? infection with a respiratory virus food poisoning due to a preformed bacterial toxin in food skin infection acquired from a dog bite infection acquired from the stick of a contaminated needle

food poisoning due to a preformed bacterial toxin in food

A difference between an acute disease and chronic disease is that chronic diseases have an extended period of __________.

illness

The _______________________occurs in an acute disease after the initial entry of the pathogen into the host (patient). It is during this time the pathogen begins multiplying in the host.

incubation period

The five periods of disease (sometimes referred to as stages or phases) include the:

incubation, prodromal, illness, decline, and convalescence periods

Community-acquired infection

infection caused by microorganisms that originated in a setting outside of a health care facility

An_______________________ is any disease caused by the direct effect of a pathogen. A pathogen may be cellular (bacteria, parasites, and fungi) or acellular (viruses, viroids, and prions).

infectious disease

In _________________ diseases, as opposed to chronic infections, the causal pathogen goes dormant for extended periods of time with no active replication

latent

In 1884, Koch published four postulates that summarized his method for determining whether a particular _________________ was the cause of a particular disease

microorganism

Contact transmission

movement of a pathogen between hosts due to contact between the two; may be direct or indirect

Horizontal direct contact transmission

movement of a pathogen from one host to another (excluding mother to embryo, fetus, or infant) in a population through physical contact or through droplet transmission

A person steps on a rusty nail and develops tetanus. In this case, the person has acquired a(n) __________ disease.

noncommunicable

In contrast to communicable infectious diseases, a _________________ infectious disease is not spread from one person to another.

noncommunicable

A patient in the hospital with a urinary catheter develops a bladder infection. This is an example of a(n) ________ infection.

nosocomial or healthcare-associated

Asymptomatic

not exhibiting any symptoms of disease

Mechanical vector

not necessary to the life cycle of an infectious agent and merely transports it without being infected

A(n) __________ pathogen causes disease only when conditions are favorable for the microorganism because of transfer to an inappropriate body site or weakened immunity in an individual.

opportunistic

The final period of disease is known as the ___________________. During this stage, the patient generally returns to normal functions, although some diseases may inflict permanent damage that the body cannot fully repair.

period of convalescence

The period of illness is followed by the ______________________, during which the number of pathogen particles begins to decrease, and the signs and symptoms of illness begin to decline. However, during the decline period, patients may become susceptible to developing secondary infections because their immune systems have been weakened by the primary infection.

period of decline

Following the prodromal period is the _______________ , during which the signs and symptoms of disease are most obvious and severe.

period of illness

Passive carrier

persons who mechanically transfer a pathogen without ever being infected by it

The ________________________ occurs after the incubation period. During this phase, the pathogen continues to multiply and the host begins to experience general signs and symptoms of illness, which typically result from activation of the immune system, such as fever, pain, soreness, swelling, or inflammation. Usually, such signs and symptoms are too general to indicate a particular disease.

prodromal period

For an acute disease, pathologic changes occur over a relatively _____________________ and involve a rapid onset of disease conditions. For example, influenza (caused by Influenzavirus) is considered an acute disease because the incubation period is approximately 1-2 days. Infected individuals can spread influenza to others for approximately 5 days after becoming ill. After approximately 1 week, individuals enter the period of decline.

short time

_____________ disease are objective and measurable, and can be directly observed by a clinician.

signs

Unlike signs, _______________ of disease are subjective. Symptoms are felt or experienced by the patient, but they cannot be clinically confirmed or objectively measured.

symptoms

Mechanical transmission

the passive transport of the pathogens on the insects feet or other body parts

Definitive host

the preferred host organism for a parasite, in which the parasite reaches maturity and may reproduce sexually

Infection

the successful colonization of a microorganism within a host

Vehicle transmission

transfer of a pathogen between hosts via contaminated food, water, or air

Vertical direct contact transmission

transfer of a pathogen from mother to child during pregnancy, birth, or breastfeeding

Indirect contact transmission

transfer of an infectious agent between hosts through contact with a fomite

Vector transmission

transmission of an infectious agent by an insect, arthropod, or animal

Zoonotic

transmitted from animals to humans

A ________ is an animal that can transfer infectious pathogens from one host to another.

vector

Certain infectious diseases are not transmitted between humans directly but can be transmitted from animals to humans. Such a disease is called __________________.

zoonotic disease (or zoonosis)

Noninfectious

A disease that cannot be spread from one organism to another.

A communicable disease that can be easily transmitted from person to person is which type of disease? A. contagious B. iatrogenic C. acute D. nosocomial

A. contagious

A blanket from a child with chickenpox is likely to be contaminated with the virus that causes chickenpox (Varicella-zoster virus). What is the blanket called? A. fomite B. host C. pathogen D. vector

A. fomite

During an oral surgery, the surgeon nicked the patient's gum with a sharp instrument. This allowed Streptococcus, a bacterium normally present in the mouth, to gain access to the blood. As a result, the patient developed bacterial endocarditis (an infection of the heart). Which type of disease is this? A. iatrogenic B. nosocomial C. vectors D. zoonotic

A. iatrogenic

Pathogen A has an ID50 of 50 particles, pathogen B has an ID50 of 1,000 particles, and pathogen C has an ID50of 1 × 106 particles. Which pathogen is most virulent? A. pathogen A B. pathogen B C. pathogen C

A. pathogen A