Immune system & Vaccines
What vaccine strategy involves vaccinating those in close contact with an infected individual in order to avoid the spread of an infectious disease?
Ring vaccination
Define incubation period.
The time between initial contact with an infectious agent and the first appearance of symptoms
What is the main animal reservoir for Ebola and Rabies?
Bats
What is the most common sources of HAIs?
Urinary tract catheters
Which bacterium is very slow growing (6-8 weeks) to produce colonies?
Mycobacterium tuberculosis
Which type of T-cell recognizes MHCI? MHCII?
CD8 cytotoxic T cell: MHC I
CD4 helper T cell: MHC II
What is the difference between the prevalence vs. incidence of disease?
Prevalence: Total number of people infected within the population at any time
Incidence: the number of new cases during a specific period of time
Which parasitic infection is associated with schizophrenia in humans and behavioral changes in rodents?
Toxoplasmosis by Toxoplasma gondii
Where can HAIs occur?
Long term care
Dialysis
Ambulatory surgical centers
Hospitals
Why are ear infections more common in children?
Eustachian tubes are shorter and more level in children → difficult for fluid to drain out of the ear.
What is the first antibody produced during an infection? Which antibody protects against infections at the mucosal membranes?
IgM : first antibody
IgA : mucosal membranes
Explain the iceberg concept and what infectious diseases would or would not follow this concept?
Iceberg: a large percentage of a problem is subclinical, unreported, or otherwise hidden from view. Thus, only the "tip of the iceberg" is apparent to the epidemiologist as those are the symptomatic cases.
Examples: COVID, tuberculosis, most infectious diseases
Examples that don't follow: Rabies
What are the four necessary components for blood-feeding vectors to feed on blood?
Anticoagulants- prevent blood clots
Vasodilators- open and dilate blood vessels
Anesthetics- induces insensitivity to pain
Immunomodulators- impacts host immune responses
What vaccine prevented a large amount of enteric infections in children?
Rotavirus vaccine
List 3 defenses of the upper respiratory tract.
Normal microflora
Hairs in nose → filter out large particles
Mucus from membranes lining nasal cavity, pharynx → trap microorganism & contains lysozyme (hydrolysis of peptidoglycan)
Ciliated epithelia → trap and expel microbes
Phagocytic cells (neutrophils, macrophages)
Local production of antibodies
Mostly IgA (secretory antibody) and IgG
Which cytokine is produced in response to viral infections?
Type I Interferon (INF-I)
What is the Ct value? What would a high Ct value indicate?
Ct value describes the number of cycles it takes in a qPCR to get amplification of DNA.
A high Ct value means a low starting DNA quantity - low viral load (inverse relationship)
What is antibody-dependent enhancement? Which disease did we discuss is associated with it?
ADE: more severe disease upon second infection with different serotype than first infection
Disease: Dengue
Which HAI fungal pathogen is drug-resistant, and can cause wound, bloodstream, and ear infections?
Candida auris
What are the possible sequelae of Strep Throat?
Rheumatic fever:
autoimmune disease
Antibody produced to M protein cross reacts with components of heart muscle, and damages the heart, especially valves
Glomerulonephritis:
Kidney function damaged by accumulation of immune complexes of IgG and IgM complexed with M proteins and deposited in the glomerulus
Kidney filtration is blocked, results in inflammation
What are the advantages and disadvantages of live attenuated vaccines compared to inactivated vaccines?
Live attenuated produce a stronger immune response compared to inactivated.
Live attenuated are not safe for immunocompromised individuals, while inactivated vaccines are safer.
What are some diagnostic tests used for direct vs. indirect detection?
Direct: Directly detecting the presence of a microorganism from the body or bodily fluids of an infected person (ex. microscopy, PCR, antigen test)
Indirect: Identify the host immune response to the pathogen (ex. ELISA, Tb skin test)
Which plasmodium species leads to the most severe malaria disease and why?
Plasmodium falciparum:
- PfEMP1 antigen surface protein get expressed on the surface of infected RBCs - bind to endothelial cell walls - avoid clearance by the spleen;
- Severe malaria- cerebral malaria (due to infected red blood cells blocking capillaries: rosetting)
- Antigenic variation to avoid immune system
List 3-4 appropriate strategies for WaSH implementation in affected populations.
Affordable
Available
Culturally acceptable
Easy to use and maintain
Environmentally friendly
Antigenic drift: mutations in hemagglutinin and neuraminidase genes, antibodies are less effective
Antigenic shift: gene reassortment when two different viruses infect same cell exchange segments, more dramatic, antibodies are no longer protective