Epidemiology Basics Quiz

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Questions and Answers

What characterizes an endemic disease within a specific geographic area?

It can only be transmitted between humans.

It occurs sporadically without a consistent presence.

It always leads to severe outbreaks and rapid spread.

It is present at a constant rate in a defined population. (correct)

How is the basic reproduction number (R0) significant in understanding an outbreak?

If R0 is greater than 1, the outbreak is likely to continue. (correct)

R0 quantifies the effectiveness of public health interventions.

R0 indicates the number of cases that will not be reported.

R0 is always less than 1 in determining disease severity.

What does the epidemic curve illustrate during an outbreak?

The timing and magnitude of the outbreak over a period. (correct)

The historical data of all related diseases in the area.

The immediate response of public health authorities.

The specific pathogens responsible for the outbreak.

Which statement about zoonotic diseases is accurate?

Most zoonotic diseases cannot be effectively transmitted human-to-human. Signup and view all the answers

In the context of epidemic investigations, why is there a delay in reporting cases to health authorities?

The date of illness onset precedes the reporting date. Signup and view all the answers

What is the ultimate goal of public health surveillance?

To produce information to guide public health actions. Signup and view all the answers

Which of the following is NOT a purpose of a surveillance system?

Monitor the health of individuals in isolation. Signup and view all the answers

Which method is employed to protect portals of entry in the context of infectious disease control?

Using bed nets to prevent malaria. Signup and view all the answers

What distinguishes communicable diseases from other types of diseases?

They can be spread directly or indirectly between hosts. Signup and view all the answers

What type of data source requires medical practitioners to report certain infectious diseases?

Statutory notifiable diseases. Signup and view all the answers

Which of the following statements is true regarding Koch's postulates?

They help establish a causal relationship between a microbe and a disease. Signup and view all the answers

Which of the following best describes sentinel surveillance?

Weekly reporting of specific health metrics by select clinics. Signup and view all the answers

Which of the following organisms is classified as a fungus?

Yeast Signup and view all the answers

What is a limitation of Koch's postulates?

Not all microbes can be associated with a specific disease. Signup and view all the answers

What is a primary benefit of measuring the burden of a disease through surveillance?

To prioritize the allocation of health resources effectively. Signup and view all the answers

In the context of public health interventions, increasing host defenses includes which of these practices?

Vaccination. Signup and view all the answers

Which statement correctly describes bacteria?

They are single-celled and lack a membrane-bound nucleus. Signup and view all the answers

Which of the following statements accurately reflects public health actions related to antimicrobial resistance?

Data on antimicrobial use and resistance is collected for broader public health understanding. Signup and view all the answers

What type of organism includes both single-celled and multicellular forms?

Fungi Signup and view all the answers

Which of the following best describes a parasite?

An organism that lives on or in a host and derives nutrients from it. Signup and view all the answers

Which term is used interchangeably with communicable diseases?

Infectious diseases Signup and view all the answers

What is the primary composition of a virus?

A core of genetic material, either DNA or RNA, within an organic particle Signup and view all the answers

Which of the following best describes the mechanism by which prions induce disease?

They cause normal proteins to misfold, creating more prions Signup and view all the answers

In direct contact transmission, how is the infectious agent primarily spread?

From one skin/mucosal surface to another Signup and view all the answers

Which of the following is an example of vector-borne transmission?

Mosquitoes transmitting a virus Signup and view all the answers

What does vehicle transmission involve?

Spread via food, water, blood, or inanimate objects Signup and view all the answers

Which type of transmission can a respiratory virus utilize?

Droplet, airborne, and vehicle (fomite) transmission Signup and view all the answers

Which of the following statements regarding airborne transmission is true?

It spreads infectious agents via fine dust or droplet nuclei suspended in the air Signup and view all the answers

What characteristic distinguishes prions from viruses during transmission?

Prions are misfolded proteins that do not carry genetic information Signup and view all the answers

What is defined as fever >38ºC accompanied by cough or sore throat?

Influenza-like illness Signup and view all the answers

What is a limitation of using sentinel surveillance for influenza-like illness?

Multiple pathogens can cause similar symptoms. Signup and view all the answers

Which scenario best defines a disease outbreak?

A single case of a new disease that poses a public health risk. Signup and view all the answers

What distinguishes a pandemic from an epidemic?

A pandemic typically crosses international boundaries. Signup and view all the answers

What is a more accurate method for determining the presence of influenza viruses?

Detection frequency of respiratory specimens. Signup and view all the answers

Which of the following best describes an epidemic?

A public health event exceeding normal frequency in a defined area. Signup and view all the answers

What role does sentinel surveillance play in public health?

It helps estimate the prevalence of influenza-like symptoms in the population. Signup and view all the answers

Which characteristic is NOT associated with a disease outbreak?

Consists of fewer cases than average occurrences. Signup and view all the answers

Study Notes

Microbial Infections and Infectious Diseases

Summary of Injuries and Diseases:
- Types of Injury and Responses:
  - Injurious stimulus types: altered physiological stimuli (e.g., increased demand, decreased stimulation), chronic irritation (physical/chemical), reduced oxygen supply, chemical injury, microbial infection.
  - Cellular responses to injurious stimuli: Cellular adaptations (e.g., hyperplasia, hypertrophy, atrophy, metaplasia), cell injury (acute & transient, progressive & severe, including DNA damage), cumulative sublethal injury over long life span, metabolic alterations, genetic/acquired chronic injury, intracellular accumulations, calcification, cellular aging, and cell death (necrosis or apoptosis).
- Causes of Diseases:
  - Vascular, inflammatory, neoplastic, degenerative, infectious, congenital, auto-immune, traumatic/toxic, environmental/endocrine.

Introduction to Communicable Diseases

Microbiology:
- The study of organisms (often small in size and simple in structure, excluding plants and animals except parasites and algae).
Communicable Diseases:
- Spread directly or indirectly between people or from other species to humans
- Caused by pathogenic microorganisms (bacteria, viruses, fungi, parasites, or prions).
Definition of an "infectious agent" using Koch's postulates (1876):
- Occurrence of the parasite in every case of the disease, absence in other cases
- Isolation from the body and pure culture of the parasite.
- Ability of the parasite to cause the disease when introduced to a susceptible host
- Re-isolation of the parasite from the experimental host that developed the disease.

Classification of Infectious Agents (Microbes)

Size, cell type, presence of nuclei, and tools for visualization are used to classify microbes.

-Helminths: Size from 1mm to 10 meters; eukaryotes with nuclei; visible with naked eye, magnifying glass, or light microscope. -Protozoa: Size from 2 µm to >100µm; eukaryotes with nuclei; typically viewed with a light microscope. -Fungi: Size from 3-10 µm (yeasts) to multicellular; eukaryotes with nuclei; often visualized with a light microscope. -Bacteria: Size from 0.5 µm to 5µm; prokaryotes (no nuclei); typically viewed using a light microscope. -Viruses: Size from 0.02 µm to 0.2 µm prokaryotes (no nuclei); often visualized using electron microscopy. -Prions: Size less than 1 nanometer, consist of proteins only; use molecular techniques for their visualization.

Disease Outbreaks and Epidemics

Outbreak/Epidemic: Cases of an illness/event exceeding normal expectancy in a community or region.
Pandemic: An epidemic extending through wide geographical boundaries, affecting a large number of people worldwide.
Endemic: Constant presence of a disease/agent within a specific geographic area/population.
Zoonosis: Diseases of animals that can be transmitted to humans.
Epidemic: An increase in cases of disease above the usual or expected frequency within a certain population.
Epidemic Curve: A graph showing the progression of disease cases over time, which can identify sources of outbreaks.

Anatomy of an Epidemic

Identification of the progression, magnitude, size, time trend and spread patterns of an outbreak over time is essential. A graph plotting the number of cases by the date of illness onset.

Public Health Surveillance

Public health surveillance: The ongoing, systematic process of collecting, interpreting, disseminating information about a health-related event for public health action to reduce morbidity and mortality.
The purpose is to measure and monitor disease burden, investigate outbreaks, evaluate interventions or practices.

Host-Microbe Relationship

Incubation Period: Time between exposure to a pathogen and the onset of symptoms.
Prodromal Period: The onset of nonspecific, general symptoms following the incubation period.
Illness Period: The period of prominent/specific symptoms and signs of an infectious disease.
Decline Period: When symptoms start to resolve and decrease in severity.
Convalescence: The recuperation phase after the symptoms decline.

Types of Infection

Acute viral infection followed by viral clearance
Acute viral infection followed by latent infection and periodic reactivation
Acute viral infection followed by chronic infection
Acute viral infection followed by a chronic infectious disease

Other Types of Infectious Agents

Defective viruses: Viruses that lack all the proteins needed to replicate, meaning they rely on another virus type to replicate.
Prions: Infectious proteins that cause other proteins to fold incorrectly.

Medically Important Gram-Positive Bacteria

Gram-positive bacteria: Includes aerobic & anaerobic spore-forming species, and non-spore-forming species.

Medically Important Gram-Positive Cocci

Gram-positive cocci, some species are highly pathogenic, some are not.

Pathogenic Neisseriae

Gram-negative diplococci; oxidase-positive bacteria that cause disease and have specific virulence factors

Medically Important Gram-Positive Bacilli

Gram-positive bacilli: Bacteria are rod-shaped, some are spores; various infections result from this group

Introduction to Fungi

Fungi (Mycetology): Eukaryotes, contain β-1,6-Glucans, β-1,3-Glucan & Chitin in their cell walls, ergosterol in cell membrane, and have a distinct cellular structure.

Fungal Infections and Disease

Superficial infections: Candidiasis (oral or vaginal thrush), dermatophytosis (Ringworm) → infections on surface of the body.
Systemic Infections: Fungal infections that have spread throughout the body, affecting multiple organs (common in immunocompromised patients).
Other (less common): Mycetoma → fungal disease, occurring locally or regionally.

Treatment of Fungal Infections

Antifungal agents – various methods for targeting different cellular and metabolic processes in fungi: -Polyenes: interfere with plasma membrane -Azoles: inhibit ergosterol synthesis -Nucleoside analogues: inhibit some fungal components (e.g., 5-fluorocytosine) -Echinocandins: impede cell wall synthesis.

Introduction to Parasites

Parasites are organisms that live on or in a host organism, deriving benefit from it, and often causing harm
Protozoa: Unicellular parasitic microorganisms with diverse life cycles and clinical importance.
Helminths: Multicellular parasitic worms (Nematodes, Trematodes, Cestodes) often involve intermediate hosts for transmission.
Arthropods: Insects and arachnids which can act as vectors for other pathogens or cause direct harm.

Malaria

Plasmodium spp.: Five parasite species that cause malaria in humans (vivax, falciparum, malariae, ovale, knowlesi).
Transmission: Vector (female Anopheles mosquitoes) transmitted via saliva.

Important Medical Viruses

Coronaviruses: Large group of viruses that cause various infections, including but not limited to some types of the common cold and significant diseases like SARS, MERS, COVID-19.
Herpesviruses: Enveloped ds DNA viruses. HSV-1 & HSV-2, VZV/Varicella-Zoster (cold sores/shingles), CMV, EBV.
Enteroviruses: Diverse group of small, non-enveloped, ssRNA viruses. Common cold-like symptoms in respiratory tract, but also affects various other body systems.
Japanese Encephalitis (JE): Enveloped, + ssRNA. Severe encephalitis, but most infections are asymptomatic.

Other Infectious Agents

Not all viruses are capable of replication independently; some rely on other viruses to complete their infectious cycles, while others rely on eukaryotic hosts. Prions are misfolded proteins that act as infectious agents.

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Description

Test your knowledge on key concepts of epidemiology, including endemic diseases, outbreak dynamics, and public health surveillance. This quiz covers critical principles such as the basic reproduction number and Koch's postulates, providing insights into infectious disease control and reporting methods.