Infectious Disease And Sexually Transmitted Infections Flashcards
Infection
When a microorganism (bacteria, virus, fungi, protozoan) invades the body of a host
Latent period
The time between infection and the development of symptoms/signs.
Pathogens: Agents of infection
- Bacteria (most are helpful)
* 1% are pathogens, disease-causing; cause harm by releasing enzymes and toxins that do damage inside host
Antibiotics - kill bacteria (many are now resistant to multiple antibiotics
- Viruses
* acellular pathogens that invade living cells (can’t survive without host)
Antiviral drugs: typically reduce severity or duration of viral infections
- More examples include Fungi, Protozoa, parasitic worms
How to ‘catch’ an infection
People:
* direct or indirect contact
Food:
* e.g. E. coli, Salmonella
Water:
* contaminated water can carry pathogens
Animals and Insects = vector transmission
* mosquitos - Zola virus, malaria
* rats/fleas - plague
Examples of good bacteria
Trillions of bacteria live in your digestive tract
Ex. Aid in digestion and vitamin absorption, compete with and exclude harmful microbes
First line of defense
Includes various physical and chemical barriers
- skin
- Epidermis
- Cilia
- Mucus
- Elevated boy temperature
- cough, tears, saliva
Antigen
A chemical structure that your immune cells recognize as different from your own and therefore foreign and we need to amount a response to
Second line of defense
Specialized cells including macrophages, T cells, and B cells launch an immune response to eliminate the pathogen
Immune system: T cells & macrophages
Macrophages (big eaters):
* surround and digest foreign matter
* aid immunity by engulfing antibody-bound pathogens
T-cells:
* fight parasites, fungi, cancer cells, infected cells
* thousands of T-cells work together to kill pathogens
Immune system: B cells & antibodies
Antibodies (Abs):
* made by B-cells
* Abs are proteins that stick to specific antigens on pathogens (humoural response)
Abs coat pathogens and make them clump together so that pathogens:
- cannot infect new cells
- can be more effectively ‘eaten’ by macrophages
The chain of infection & ways to break the chain
- pathogen - disinfectants, chlorinations of water
- reservoir (long term host)- medical treatment and testing, quarantine
- portal of exit - masks, condoms
- means of transmission - sanitary practices, safer sex
- portal of entry - masks, insect repellant
- new host - immunization, health promotion, medical treatment
Chain of infection: Influenza
Pathogen - Influenza virus
Human reservoir - Human #1 infected
portal of exit - human #1 sneezes; pathogen exits mouth or nose
Transmission - Airborne droplets or indirect transfer through a surface
portal of entry - human #2 inhales; pathogen enters nose or mouth
New host - Human #2 infected
Vaccination
Small quantity of inactive pathogen injected to create memory cells (T- and B-cells)
- when you encounter the actual pathogen, your immune system can fight it off (with antibodies)
- eliminates pathogen before signs/symptoms experienced
Smallpox
A virus that plagued humans throughout history
* killed more people than every infectious disease combined
Vaccination has led to the eradication of smallpox (~35% mortality)
Measles
Causes inflammation of the brain, brain damage, seizures, deafness, and for 150000 cases per year globally, it leads to death
“Most deadly of all childhood rash/fever illnesses” - WHO
Difference between T-Cells & B-Cells
B-Cells: produce antibodies that are used to attack invading bacteria, viruses, and toxins
T-Cells: destroy the own body’s cells that have been taken over by viruses or become cancerous
Infectious Disease in Canada
- Colds
- Influenza
- Hepatitis
- Meningitis
- Reproductive & Urinary infections
- Sexually transmitted infections
Common cold (rhinovirus, coronavirus)
Spread by coughs, sneezes, direct, indirect contact
~200 types (so you keep getting it)
Prevention: washing hands
Cure: Your immune system
* rest, fluids, mild exercise, nutrition
* medications mask symptoms
Flu (Influenza virus)
More severe symptoms (aches, chills, dry cough, weakness) that last longer than a cold
1918 Spanish flu outbreak:
* killed 50-100 million people
* 50% of worlds population infected
* killed those with the healthiest immune systems (typically ages 18-40)
Hepatitis (virus)
Symptoms: fever, headaches, fatigue, diarrhea, vomiting, aching joints
- Viruses (A-G) cause inflammation of the liver
- Viruses (A & E) transmitted by contaminated water
- Viruses (B,C,D) transmitted through sexual contact
Meningitis (bacterial or viral)
Infection of the membranes surrounding the brain and spinal cord
Symptoms: fever, drowsiness, confusion, headache, nausea, vomiting
- viral meningitis clears up on its own
- bacterial meningitis is very serious and requires antibiotics immediately
Reproductive and Urinary tract infections
Vaginal infections:
* symptoms include itching, burning, discharge
Penile infections:
* symptoms include redness, irritation, pain during urination or intercourse, discharge
Urinary tract infections (UTIs):
* typically caused by bacteria
* symptoms include burning sensation while urinating, chills, fever, fatigue, blood in urine
* more common in females
Ways to support your immune system
- washing your hands
- adequate sleep and exercise
- a balanced diet
Bacterial STIs
- chlamydia
- gonorrhea
- infectious syphillis
- pelvic inflammatory disease (PID)
Viral STIs
- human papillomavirus (HPV)
- Genital Herpes (HSV 1 and HSV 2)
- human immunodeficiency virus (HIV)
- Hepatitis B (HBV)
Chlamydia (most common bacterial STI in Canada)
Caused by chlamydia trachomatis
- it is common and easily treatable with antibiotics
- 2x more common in females then males
- if left untreated, can lead to ectopic pregnancy; sterility in females (and males)
Symptoms (often asymptomatic):
* discharge
* burning when urinating
Gonorrhea
Caused by Neissaria gonorrhoeae
- often asymptomatic
- in females can cause PID
- in males can cause inflammation of the urethra, prostate, epididymis
Syphillis
Caused by Treponema pallidum
- transmitted through a break in the skin, via kissing, oral, vaginal, or anal sex
Primary: ulcer at site of infection (days to weeks after contact); not usually painful; contains high numbers of bacteria and highly contagious
Secondary: flu-like symptoms; rash over the body, hands and feet; ~ 2 months later
Tertiary: neurological and cardiovascular effects; blindness; years to decades later
Treatment: antibiotics if early enough
Human Papilloma Virus (most common viral STI in North America)
> 100 types of HPV
Cause common warts, genital warts, genital cancers
* all cervical cancers caused by HPV
* spread by sexual contact
Immune system often clears the infection (some cases infection persists to cause genital warts or cancer)
Prevention: Gardasil vaccination
HPV Progression:
Long latency provides ample opportunity to remove pre-cancerous cells
Herpes Simplex Virus 1 & 2
Travels along nerves and lays dormant in nerve cells; infection is life-long
- commonly transmitted through oral sex
- prevention is difficult
- outbreaks can be triggered by stress, illness, fatigue, sun exposure, intercourse, and menstruation
Prevention: condom use
Treatment: antivirals like acyclovir can lessen symptoms; there is no cure
Human Immunodeficiency virus (HIV)
Transmission:
* not spread by casual contact; requires blood-blood or fluid-blood contact
Most common: unprotected sex
HIV and AIDS
HIV infects immune cells (T-cells)
The immune system launches a response but:
* HIV “hides” inside immune cells (and slowly kills them)
* HIV replicates too fast for the immune system to fight it
* HIV mutates (changing its antigens) and avoids elimination
An untreated HIV infection typically leads to AIDS within 10 years
Severely compromised immune system
* death due to opportunistic infections
Main treatment:
* highly active antiretroviral therapy (HAART)
Combination of (usually) 3 different kinds of drugs that target various stages of the HIV viral life cycle
Key takeaway from HIV in Canada
It does not discriminate
* shown in heterosexual individuals (33%), gay individuals (50%), and intravenous drug users (17%)
Opportunistic infection
An infection caused by pathogens (bacteria, viruses, fungi, or parasites) that take advantage of an opportunity not normally available
Ex. A host with a weakened immune system
Steps to the immune response
Phase 1: Recognition - when a pathogen breaches the body’s physical and chemical barriers it initiates the first phase of the immune response
Phase 2: Proliferation: the activated helper and killer T-cells multiply, thereby amplifying the immune response to the pathogen
Phase 3: Elimination: the activated T and B cells then undergo a transformation to become either memory cells or effector cells.
Phase 4: Slowdown: Regulatory T cells inhibit lymphocyte proliferation and induce lymphocyte death, causing a slowdown of the immune response
Pelvic Inflammatory Disease
Usually a complication of untreated gonorrhea or chlamydia
- is an ascending infection that progresses from the vagina to the cervix to the uterus, oviducts, and pelvic cavity
- it can lead to infertility, ectopic pregnancy, and chronic pelvic pain
