UNIT 6 Objectives pt. 2 Flashcards
Define Host
An organism that supports the life cycle of a pathogen, providing nutrients and shelter
Define Infection
The invasion and multiplication of pathogens (bacteria, viruses, fungi, etc.) in a host, potentially leading to disease.
Define Contamination
The presence of harmful microorganisms on surfaces, food, water, or the body.
Define Epidemiology
The study of how diseases spread, their causes, and their effects in populations.
Define Etiology
The study of the cause or origin of a disease
Define Index case
The first patient identified in an epidemiological study of an outbreak or disease
Define Parasite
An organism that lives on or inside a host and benefits at the host’s expense
Define Pathogen
Any microorganism or agent that causes disease
Define Opportunistic Pathogen
A microorganism that causes disease in a host with a weakened immune system or when the normal flora is disturbed
Define Pathogenicity
The ability of an organism to cause disease in a host
Define Virulence
The degree of harmfulness or severity of disease caused by a pathogen
Define Infectious
Diseases caused by microorganisms that can be transmitted from person to person
Define Non-infectious
Diseases not caused by microorganisms (e.g., genetic, environmental)
Define Communicable
A disease that can be spread from one individual to another
Define Non-communicable
A disease that is not transmitted from person to person
Define Contagious
A highly communicable disease, spread easily from person to person
Define Symptoms
Subjective evidence of disease reported by the patient (e.g., pain, fatigue)
Define Signs
Objective evidence of disease observable by others (e.g., rash, fever)
Define Syndrome
A collection of symptoms and signs that together characterize a particular disease or condition
Define Subclinical
A disease or infection that does not show noticeable symptoms
Define Asymptomatic
A condition in which a person carries a pathogen but shows no symptoms of disease
Define Primary
The initial stage or infection, the first appearance of disease
Define Secondary (disease)
An infection or disease that occurs as a result of an existing condition or disease
Define Nosocomial
Infections acquired in a healthcare setting (hospital, clinic)
Define Zoonosis
A disease that can be transmitted from animals to humans
Define Acute
A disease with a rapid onset and short duration
Define Chronic
A disease that persists for a long period, often with gradual onset
Define Subacute
A disease that is intermediate between acute and chronic
Define Latent
A disease that is dormant or inactive but can become active later
Define Local
A disease confined to a specific part or area of the body
Define Focal
A localized infection that spreads from one site to other areas
Define Systemic
A disease affecting the entire body, often involving multiple organs
Define Bacteremia
The presence of bacteria in the bloodstream
Define Toxemia
The presence of toxins in the bloodstream
Define Septicemia
A systemic infection in which bacteria are present and multiply in the blood
Define Iatrogenic
A condition caused by medical treatment or intervention
Define Endogenous
Infections caused by pathogens that are normally part of the host’s microbiota (acne)
Define Superinfection
An infection that occurs on top of another;
often caused by the overgrowth of resistant microorganisms following antibiotic treatment
Define Incubation
The period between exposure to a pathogen and the appearance of symptoms
Define Prodromal
The early stage of disease, where mild symptoms appear
Define Illness
The stage when the disease symptoms are most severe
Define Decline
The period during which symptoms subside and the body begins to recover
Define Convalescence
The recovery phase after the disease, where the body regains strength
Define Direct Contact
Transmission of pathogens through physical touch or contact (e.g., skin-to-skin)
Define Indirect Contact
Transmission through contaminated objects or surfaces (e.g., doorknobs, towels)
Define Droplet Transmission
Spread of pathogens through respiratory droplets from coughing or sneezing
Define Vehicle (4 types)
Air
Water
Food
Blood
Airborne: Transmission through air particles carrying pathogens
Waterborne: Spread through contaminated water sources
Foodborne: Transmission via contaminated food
Bloodborne: Spread through contact with infected blood
Define Vector
An organism (typically an insect) that transmits a pathogen from one host to another (e.g., mosquitoes transmitting malaria)
Define Carrier
A person or animal that carries and can transmit a pathogen without showing symptoms
Define Fomite
An inanimate object that can carry and spread pathogens (e.g., doorknobs, medical instruments)
Define Fecal-Oral
Transmission through ingestion of fecal-contaminated food or water
Define Morbidity
The incidence or prevalence of a disease in a population
Define Mortality
The number of deaths due to a disease in a population
Define Incidence
The number of new cases of a disease in a specific period of time
Define Prevalence
The total number of cases of a disease (new and existing) in a population at a given time
Define Endemic
A disease that is regularly found and maintained within a particular geographic area or population
Define Sporadic
Disease occurrences that are irregular or infrequent within a population or area
Define Epidemic
A sudden, widespread outbreak of a disease in a population or geographic area
Define Pandemic
An epidemic that has spread across multiple countries or continents, affecting a large proportion of the population
What are Koch’s postulates? (4)
- The suspected agent (bacterium, virus, etc.) must be present in every case of the disease.
- That agent must be isolated and grown in pure culture.
- The cultured agent must cause the disease when it is inoculated into a healthy, susceptible experimental host.
- The same agent should be found in the diseased experimental host.
What are the exceptions to Koch’s postulates?
Some pathogens have not been cultured in the laboratory
For example, pathogenic strains of Mycobacterium leprae (lep’rī), which causes leprosy, have never been grown on laboratory media.
Some diseases are caused by a combination of pathogens or by a combination of a pathogen and physical, environmental, or genetic cofactors.
In such cases, the pathogen alone is unable to cause disease, but when accompanied by another pathogen or the appropriate cofactor, disease results.
Ethical considerations prevent applying Koch’s postulates to diseases and pathogens that occur in humans only
In such cases, the third postulate, which involves inoculation of a healthy susceptible host, cannot be satisfied within ethical boundaries.
For this reason, scientists have never applied Koch’s postulates to prove that HIV causes AIDS; however, observations of fetuses that were naturally exposed to HIV across their placentas from their infected mothers, as well as accidentally infected health care and laboratory workers, have in effect satisfied the third postulate.
What are the three major types of reservoirs of human infection?
- Human Reservoirs
- Animal Reservoirs (Zoonoses)
- Environmental Reservoirs
What are the three major types of reservoirs of human infection? Can you give me examples of each type?
- Human Reservoirs
-
Human Reservoirs:
- Description: Humans can serve as the primary source of infection, either showing symptoms (symptomatic carriers)
Or carrying the pathogen without symptoms (asymptomatic or latent carriers).
-
Examples:
- Symptomatic: A person with an active case of tuberculosis or influenza.
- Asymptomatic: A person who carries the bacterium Neisseria meningitidis without showing symptoms but can still transmit it to others.
What are the three major types of reservoirs of human infection? Can you give me examples of each type?
- Animal Reservoirs (Zoonoses)
-
Animal Reservoirs (Zoonoses):
- Description: Animals, both wild and domestic, can harbor pathogens that can be transmitted to humans. These infections are known as zoonotic diseases.
-
Examples:
- Rabies (transmitted by dogs, bats, or raccoons).
- Lyme disease (transmitted by ticks from animals like deer).
- Salmonella (can be carried by poultry, reptiles, and other animals).
What are the three major types of reservoirs of human infection? Can you give me examples of each type?
- Environmental Reservoirs
-
Environmental Reservoirs:
- Description: Pathogens can exist in the environment (soil, water, or inanimate objects), where they can persist and potentially infect humans when they come into contact with contaminated surfaces or substances.
-
Examples:
- Clostridium tetani (found in soil and causes tetanus).
- Vibrio cholerae (found in contaminated water and causes cholera).
Describe the 7 modes of transmission.
Name examples of diseases that use a specific mode of transmission.
-
Direct Contact: Transmission occurs through direct physical contact between an infected person or animal and a susceptible person.
Examples:
- HIV (transmitted through sexual contact).
- Herpes simplex virus (transmitted through skin-to-skin contact). -
Indirect Contact: Pathogens are transmitted via contaminated objects or surfaces (fomites).
Examples:
- Common cold (via contaminated surfaces like doorknobs or phones).
- Norovirus (transmitted through contaminated food or objects). - Droplet Transmission: Pathogens are spread through respiratory droplets when a person coughs, sneezes, or talks.
Examples:
- Influenza (spread via droplets from sneezing or coughing).
- COVID-19 (spread through respiratory droplets).
- Airborne Transmission: Pathogens are carried on dust particles or droplets that remain suspended in the air for long periods, traveling over long distances.
Examples:
- Tuberculosis (spread through the air when an infected person coughs or sneezes).
- Measles (highly contagious, transmitted through the air).
- Vector Transmission: Pathogens are transmitted by vectors, which are often arthropods (e.g., insects) that carry and spread the pathogen.
Examples:
- Malaria (transmitted by Anopheles mosquitoes).
- Lyme disease (transmitted by ticks).
- Vehicle Transmission: Transmission occurs via a common vehicle, such as air, food, water, or blood.
Examples:
- Cholera (spread via contaminated water).
- Hepatitis B (spread via contaminated blood products).
- Fecal-Oral Transmission: Pathogens are transmitted through ingestion of fecal-contaminated food, water, or surfaces.
Examples:
- Hepatitis A (transmitted through contaminated food or water).
Describe the 5 portals of entry. Name examples of diseases that use a specific portal of entry.
- Mucous Membranes: Pathogens enter through the moist lining of body cavities such as the respiratory, gastrointestinal, and urogenital tracts.
Examples:
- Influenza (enters through the respiratory tract).
- Hepatitis A (enters through the gastrointestinal tract).
- Skin: Pathogens can enter through breaks or lesions in the skin, or via vectors like mosquitoes.
Examples:
- Tetanus (enters through cuts or puncture wounds).
- Malaria (transmitted by mosquito bites through broken skin).
- Parenteral Route (directly into the bloodstream): Pathogens are introduced directly into the bloodstream or tissues by a needle, bite, or surgery.
Examples:
- HIV (transmitted via blood through needle sharing).
- Hepatitis B (transmitted via blood or contaminated needles).
- Genital/Urinary Tract: Pathogens can enter through the genital or urinary tract, often through sexual contact.
Examples:
- Chlamydia (enters through the urogenital tract during sexual contact).
- Human papillomavirus (HPV) (enters through the genital tract during sexual contact).
- Conjunctiva (Eye): Pathogens can enter through the mucous membranes of the eye.
Examples:
- Pink eye (conjunctivitis) (caused by bacteria or viruses).
- Trachoma (bacterial infection transmitted through eye contact or flies)
Nosocomial infections:
a. What factors influence nosocomial infections?
- Exposure to numerous pathogens present in the health care setting, including many that are resistant to antimicrobial agents
- The weakened immune systems of patients who are ill, making them more susceptible to opportunistic pathogens
- Transmission of pathogens among patients and health care workers—from staff and visitors, to patients, and even from one patient to another via activities of staff members (including invasive procedures and other iatrogenic factors)
Nosocomial infections:
b. What problems are associated with their treatment and prevention?
- Antibiotic Resistance: Nosocomial infections are often caused by drug-resistant bacteria, making treatment more difficult and expensive.
- Limited Treatment Options: Many hospital-acquired pathogens are resistant to multiple antibiotics, reducing the effectiveness of standard treatments.
- Delayed Diagnosis: Hospital-acquired infections may not be diagnosed immediately, especially if symptoms overlap with the patient’s primary condition.
- Cross-Transmission: Hospitals are high-risk areas for cross-contamination, where patients, healthcare workers, and visitors can all be vectors for infection.
- Resource Constraints: Limited availability of personnel, time, or resources for infection control can lead to lapses in prevention practices.
Nosocomial infections:
c. Which organisms are frequently the cause for these types of infection?
- Gram-positive bacteria:
- Staphylococcus aureus (MRSA)
- Enterococcus species (VRE) - Gram-negative bacteria:
- Escherichia coli
- Pseudomonas aeruginosa
- Klebsiella species
- Acinetobacter baumannii -
Fungi:
- Candida species (especially Candida albicans) -
Viruses:
- Clostridium difficile (responsible for healthcare-associated gastrointestinal infections)
- Norovirus (causing gastrointestinal infections)
Nosocomial infections:
d. What is the most effective way to control nosocomial infections?
Hand washing
Disinfection
Surgical and Medical asepsis
Good housekeeping, bathing, Proper hygiene
Sanitary handling of food
Thorough cleansing of the surgical field
Use of sterile instruments, gloves, gowns, caps, and masks
Isolation of particularly contagious or susceptible patients
Establishment of an HAI control committee charged with surveillance of nosocomial diseases and review of control measures.
Nosocomial infections:
e. What precautions do health care professionals follow?
- Standard Precautions: hand hygiene, use of gloves, masks, eye protection, and gowns
- Transmission-Based Precautions: Additional measures based on the mode of transmission, isolation for airborne, droplet, or contact precautions.
- Isolation Protocols: Placing patients with contagious or resistant infections in isolation
- Personal Protective Equipment (PPE): Using appropriate PPE like gloves, gowns, face shields, and N95 masks
- Regular Screening and Surveillance: Monitoring and screening for nosocomial infections to identify and control outbreaks early
What is the role of the CDC?
The Centers for Disease Control and Prevention (CDC) collaborates to create the expertise, information, and tools that we need to protect our health through health promotion, prevention of disease, injury and disability, and preparedness for new health threats.
- Monitors and controls infectious and non-infectious diseases
- Promotes health education and preventive behaviors
- Conducts research and collects health data
- Prepares for and responds to health emergencies
- Works to reduce health disparities and improve health equity
- Supports global health initiatives and collaborations
What is the direct product of an operon?
RNA
