SAS13 Midterm 1

flashcards for weeks 1-4

Antonie van Leeuwenhoek

Dutch microbiologist who discovered protists and bacteria, and made the first microscope lenses

Johanna Westerdijk

Dutch botanist and first female professor in the Netherlands who led research into Dutch elm disease

Francis Collins

American geneticist who discovered the genes associated with cystic fibrosis and Huntington’s disease

Christiaan Eijkman

Dutch physician who conducted research with chickens on beriberi disease and discovered unpolished rice (which lacked vitamin B1) was causing this disease

Rachel Carson

American marine biologist whose book Silent Spring warned of the dangers to all natural systems posed by chemical pesticides such as DDT

Tu Youyou

Chinese pharmaceutical chemist who led research on treatments for malaria and discovered artemisinin and dihydroartemisinin. Through her accomplishments, she became the first Chinese woman to win a Nobel Prize.

animalcules

an archaic term for microorganisms, including bacteria, protozoans, and very small animals

Factor V Leiden

a hereditary point mutation of one of the clotting factors in the blood

disease taxonomy

a nomenclature system for the classification for diseases

World Health Organization

a specialized agency of the United Nations responsible for international public health

International Classification of Diseases (ICD)

a globally used medical classification system maintained by the WHO that is used in epidemiology, health management, and for clinical purposes

ICD Clinical Modification

a system used by physicians and other healthcare providers to classify and code all diagnoses, symptoms, and procedures recorded during hospital care

medical coding

a universal medical alphanumeric coding system for healthcare diagnosis, procedures, medical services, and equipment

circulatory (cardiovascular) system

circulates blood around the body via the heart, arteries, and veins, delivering oxygen and nutrients to organs and cells and carrying their waste products away

digestive system

system to absorb nutrients and remove waste via the gastrointestinal tract

endocrine system

glands located throughout the body that produce hormones which regulate a wide variety of bodily functions

integumentary system

system composed of skin, hair, nails, sweat, and other exocrine glands

immune system

a complex network of organs, cells and proteins that defends the body against infection, whilst protecting the body's own cells. The immune system keeps a record of every microbe it has ever encountered so it can recognize and destroy the microbe quickly if it enters the body again.

lymphatic system

maintains fluid levels in the body and produces antibodies for protection against infection and disease

muscular system

consists of all the body muscles (3 types: smooth, cardiac, and skeletal) which enable us to produce body movement

nervous system

collects and processes information from the senses via nerves and the brain, and tells muscles to contract to cause physical actions

central nervous system structures

brain and spinal cord

urinary (renal) system

filters blood through kidneys to produce and excrete urine to get rid of waste

reproductive system

the reproductive organs required for the production of offspring

respiratory system

brings air into and out of the lungs to absorb oxygen and remove carbon dioxide

structures of the upper respiratory system

nasal cavity and pharynx

structures of the lower respiratory system

the trachea, bronchi, lungs, and alveoli

skeletal system

composed of bones and cartilages that support and protect various body parts

disease etiology

the (underlying) cause of a disease

infectious disease agents

viruses, bacteria, fungi, protozoa, and helminths

genetic disease

a harmful mutation of a gene

environmental disease

too much of a bad thing, or not enough of a good thing

nutritional deficiency disease examples

scurvy, beriberi, anemia, goiter

thiamin

vitamin b1

mortality

number of deaths due to a disease divided by the total population

excess deaths

deaths that exceed the number of deaths expected each year

case fatality rate

the proportion of people who get a disease and also die from it

morbidity

another term for having a disease or illness

prevalance

the number of diseased individuals in a population (number of cases per number of people in the population)

incidence

number of new cases over a defined period of time

nationally notifiable disease

a disease that, when diagnosed, requires health providers to report to state or local public health officials

Covid-19 antigen test

an antigen test requires a nasal swab and directly detects SARS-CoV-2 viral protein, is very fast, and can be used to diagnose Covid-19. It cannot detect small amounts of the virus and it not very accurate for asymptomatic individuals.

Covid-19 PCR test

a PCR test requires a nasal swab and amplifies nucleic acids to detect viral RNA which helps make even small traces of the virus visible in a test sample. PCR tests are the most reliable and accurate, but must be performed by a healthcare provider and results take a few days.

Covid-19 antibody test

an antibody test is a blood test that detects the presence of Covid-19 antibodies, but cannot be used to diagnosis a current infection because antibodies are only present in individuals who have recovered or been vaccinated

DALY (Disability Adjusted Life Years)

measure of overall disease burden, expressed as cumulative number of years lost due to ill-health, disability, or early death

disease burden

the overall impact of an illness or disease, such as disability, impairment, injuries, and risk factors

disease definition

a particular abnormal condition that negatively affects the structure or function of all or part of an organism

symptoms vs signs

symptoms are noticed by the patient whereas signs are noticed by the physician

asymptomatic

absence of symptoms

presymptomatic

absence of symptoms but a positive test result

normativist

emphasize the undesirability of diseases and the harms and limitations they bring to a patient and/or society 

naturavist

believe disease requires the presence of biological dysfunction (impairment of individual survival and reproduction)

Body Mass Index (BMI)

a person’s weight in kilograms divided by the square of height in meters

gut microbiome

the microbial communities in our digestive tract that can affect our health and weight

disease etymology

the origin of disease names

societal and personal impacts of disease names

the name of a disease can influence public perception

WHO guidelines for naming diseases

diseases should not be named after geographic locations, the names of people, occupations, animals, or food

infection

an invasion of the body by pathogens

types of pathogenic (infectious) organisms

parasites (protozoa and helminths), fungi, bacteria, viruses, and prions

local / systemic infections

local: confined to a small region of the body

systemic: widespread infection in many parts of the body (travels through blood or lymph)

focal infection

pathogens are localized in one region but cause acute or chronic disease/symptoms at another part of the body

primary / secondary infections

primary: the initial infection within a patient

secondary: infections that would not normally cause disease under normal conditions, but occur when an opportunity is provided (such as an infection due to an open wound)

acute / chronic / latent infectous diseases

acute: symptoms develop rapidly and disease runs its course relatively quickly

chronic: symptoms develop slowly and stay for a long time

latent: symptoms appear long after infection

opportunistic pathogens

pathogens that would not normally infect a healthy host, but when an opportunity is presented (such as an open wound), they can enter the body

communicable disease

disease that can be transmitted from one host to another

modes of communicable disease transmission

direct: human-to-human contact, such as shaking hands

indirect: contact with a fomite, such as touching a doorknob

airborne: droplets and microscopic particles called aerosols, expelled during sneezing, coughing, talking, etc.

bodily fluids: contact with an infected individual’s bodily fluids

contamination: fecal contamination of food or water

fomite

a non-living surface or object that can carry pathogens

non-communicable

disease arising from outside of hosts or from unhealthy behaviors

contagious disease

communicable diseases that are easily spread

congenital

a condition or trait that is present at or before birth

half-life of pathogens

can only survive on hands for a couple hours, but can survive up to a week on certain surfaces (however, viruses can only survive on copper for a few hours)

how does soap protect against pathogens?

destroys the lipid membranes of viruses

how does hand sanitizer help protect against pathogens?

the alcohol in hand sanitizer kills pathogens on skin

how do N95 masks prevent infection?

N95 respirators have a network of fibers that filter out any particles larger than 0.3 microns. N95s also have an electrocharged layer that makes virus material stick to it.

relative sizes of respiratory droplets, aerosols, and virus particles

droplets: 5-10 microns

aerosols: 1-3 microns

Covid-19: 0.1-0.5 microns

means to reduce airborne and droplet transmission

masks and social distancing

S-I-R model of disease spread

S(susceptible): individuals who are not yet infected and are healthy but don’t have antibodies

I(infected): individuals who are infected and contagious

R(recovered): individuals who are immune, no longer capable of spreading, and healthy with antibodies

R₀ (basic reproduction number)

average number of new infections that one infectious person generates, in an entirely susceptible population, during the time they are infectious 

R₀ > 1 =

an epidemic will occur (the larger R₀ is, the harder it is to stop the epidemic)

R₀ < 1 =

infection will not spread

R_t (effective reproduction number)

the expected number of new infections caused by an infectious individual in a population where some individuals are no longer susceptible

ways to estimate R₀ and importance of these methods

contact tracing and case reporting, both of which help locate the source of an outbreak and prevent spread

contact tracing

a process of identifying, assessing, and managing individuals who are infected or have been in contact with an infected individual

case reporting (surveillance)

collecting reports of of individuals with a disease

epidemic

an outbreak of disease that spreads quickly in a certain region

pandemic

an epidemic that is actively spreading beyond the initial individual region to other parts of the world

herd immunity and how to achieve it

when a large enough proportion of a population is immune or vaccinated, it limits further disease spread.

70-95% of a population would need to be immune/vaccinated to achieve herd immunity; equation: [1-(1 / R₀)]x100%

vaccine hesitancy

reluctance or refusal to accept vaccination despite availability of vaccine services and supporting evidence

Faroe islands measles epidemic of 1781

an instance where a virus self-eradicated because the population was not big enough (50,000 people required to sustain a virus)

pathogen attenuation

purposeful weakening of pathogen virulence, while still keeping it viable to be used in vaccines

endemic disease

a consistently present disease in a certain population (without outside influence such as travel)

vaccination

a biological preparation that stimulates the body’s immune response and provides active acquired immunity to a particular infectious disease

zoonotic diseases

diseases spread between animals and humans

what animal is considered a reservoir host of diseases?

bats (because they are the only mammals that fly which helps with virus dispersal, and they roost in large numbers which aids transmission cycles)

spillover zoonoses

the transmission of a pathogen from an animal to a human, recognized as the predominant cause of many emerging infectious diseases

what was the epicenter of the Covid-19 pandemic?

a ‘wet market’ in Wuhan, China

lab leak theory

theory that the Covid-19 virus originated in a lab

vector-borne disease

a disease that results from an infection transmitted to humans and other animals by blood-feeding insects

Plasmodium life cycle and species

1. mosquito ingests parasite from the blood of an infected human carrier

2. parasites reproduce asexually in the midgut of mosquito and migrate to the salivary glands

3. during a blood meal, the malaria-infected female mosquito inoculates the parasite into a human host

4. once in a human’s blood, the parasite infects RBC’s and start replicating

5. infected RBC’s burst and release new parasites into the bloodstream

vector control

methods to limit or eradicate animal or insect carriers which transmit disease pathogens to humans