Infectious Disease Quiz 3

Pathogen Factors

Virulence, Mode of entry, Number of organisms (one infectious influenza or 1000 bacteria for gonorrhea)

Host Factors

Health status, Nutritional status, Hygiene, Age, Immune status, Lifestyle/behavior

Environment Factors

Physical (geographic location, climate, season); Availability of appropriate reservoirs, intermediate hosts, vectors; Housing conditions (sanitary?), Waste disposal, Adequate health care, Availability of potable water

Chain of Infection

1. Pathogen

2. Source of pathogen (reservoir)

3. Portal of exit

4. Mode of transmission

5. Portal of entry

6. Susceptible host

Strategies for Breaking Chain of Infection

Eliminate/contain reservoirs of pathogens; Prevent contact with infectious substances; Eliminate means of transmission; Block exposure to entry pathways; Reduce/eliminate susceptibility of potential hosts; Practice effective hand hygiene; Practice insect/rodent control measures; Disposing of sharps/infectious waste properly; Engineering controls (lab hood)

Reservoir

Place where pathogens can multiply/survive until transferred to a host (may be alive or inanimate)

Examples of Live Reservoirs

Humans, animals/pets, farm animals, insects, arachnids; Person or animal may not be experiencing illness caused by pathogens (carriers); Ticks carry lyme disease, Anopheles carry malaria, Fleas carry the plague

Viral Zoonotic Diseases

Avian Influenza, Rabies

Bacterial Zoonotic Diseases

Lyme disease, Plague

Fungal Zoonotic Disease

Ringworm (Tinea infection)

Protozoa Zoonotic Disease

Babesiosis

Helminth Zoonotic Disease

Dog tapeworm

Each year there are ___new human diseases with ___ of them having animal sources

5, 75%

Arthropods

Animals commonly associated with human infections; Insects (fleas, mosquitoes, lice); Arachnids (mites, ticks); When involved in the transmission of infectious diseases, they are called vectors

More than ___ species of flea can transmit bacteria that causes the plague

80

Nonliving Reservoirs

Air, soil, dust, contaminated water, foods, fomites

Fomites

Inanimate objects capable of transmitting pathogens (bedding, towels, hospital equipment, utensils, phones, door handles, etc.)

Staph Aureus Carrier

Transmits pathogens to susceptible patients (ex. baby, surgical patient, immunocompromised); Hospital acquired infection and possible epidemic

Most Common Modes of Transmission of Infectious Diseases

1. Contact (direct - skin to skin/mucous membranes; indirect - fomites)

2. Droplet (greater than or equal to 5 micrometers in diameter)

3. Airborne (evaporated droplet residue < 5 micrometers in diameter)

4. Vehicular (contaminated objects like food, water, or dust)

5. Vector (arthropods)

Public Health Agencies

Strive to prevent epidemics and identify/eliminate any that do occur; Educate the public and explain how diseases are transmitted/proper sanitation procedures; Healthcare personnel participate in reporting cases of communicable diseases to proper agencies (CDC - national, WHO - global, DPH - state)

Control of an Infectious Disease

Ongoing operations/programs aimed at reducing the incidence or prevalence of a disease

Elimination of an Infectious Disease

Reduction of case transmission to a predetermined very low level (< 1 in 1,000,000)

Eradication of an Infectious Disease

Achieving a status where no further cases of that disease occur anywhere and where continued control measures are unnecessary

Nationally Notified Infectious Diseases

Must be reported to CDC by all 50 states whenever they are diagnosed; about 65 of them

Genital Chlamydial Infections

Nationally Notifiable; Increased in 2019; May, July, October, December are most common months; Most common age is 15-24; Greater number of cases among females because they are more likely to get tested (many males are asymptomatic)

Gonorrhea

Nationally Notifiable; Increased in 2019 May, July, October, December are most common months; Most common age is 15-24; Number of cases are similar among genders (both tend to get tested; symptomatic)

Syphilis

Nationally Notifiable; Increased in 2019

Healthcare Epidemiology

Study of the occurrence, determinants, and distribution of health and disease within healthcare settings; Primary focus is control and prevention of HAIs; Includes any activities designed to study and improve patient care outcomes

Healthcare Associated Infections

Disease acquired within healthcare facilities; Up to 14 days after discharge; Does NOT mean iatrogenic infection; 2 million in the US develop an HAI each year; 1 in 31 hospital patients has at least one HAI; 1 in 22 American patients with an HAI die

Community-Acquired Infections

Present or incubating at time of admission into healthcare facility; Acquired outside

Iatrogenic Infection

Infection from a medical or surgical treatment; All iatrogenic infections are HAIs, but not all HAIs are iatrogenic

What procedures can cause HAIs?

Wisdom teeth removal (iatrogenic); Catheters (iatrogenic); Ventilation, IV (iatrogenic)

Most Common Types of HAIs

Clostridium Difficile-Associated Diarrhea (GIT); Urinary Tract Infections; Surgical Site Infections; Lower Respiratory Tract Infections (mainly pneumonia); Bloodstream Infections

C. Diff

Strong declines in C.diff are likely due to pandemic-related improvements in hand hygiene, PPE practices, and environmental cleaning in healthcare settings; Most dangerous when it proliferates after a course of antibiotics; Most common bacteria in the US that causes HAIs; 29,000 US deaths each year; 3-5% of population are carriers