Transcript Ch 10.3-5 Epidemiologyx

Ch.10.3-5 Epidemiology
Microbiology
10.3 Predisposing
Factors
• Anatomical-UTI
• Genetic-Cystic
fibrosis
• Disease specific
• Climate & Weather
• Overall health
• Age
• Diet
10.3 Disease
Development
Stage 1: Incubation
period
Stage 2: Prodromal
period
Stage 3: Acute period
Stage 4: Convalescence
period
10.3 Disease
Reservoirs
Animals are natural reservoirs
for many diseases
• Plague-rodents
• Chagas-armadillos
• Babeiosis-ticks
• Rabies-raccoons, skunks,
bats
• Cholera-shellfish
• SARS-bats
• Ebola-bats, primates
Human reservoir
Non-living reservoir
10.3 Infectious
Disease
Transmission
Direct contact
Indirect contact
• Aerosolized-air
• Food & water
contamination
• Fomite-objects
• Vector-animal carriers
10.3 Ecology,
Epidemiology &
Evolution of
Pathogens
Zoonose-disease
transmitted between
different species.
Ecological competenceability of a pathogen to
survive and compete
Virulence-the degree of
pathogenicity, fatality
rates.
10.3 Safety in the
Microbiology
Laboratory
Center for Disease Control
(CDC) biohazard levels 1-4
• BSL1 Minimum risk, normal
protection: gloves, goggles
• BSL 2 Bacteria & viruses that
cause treatable disease, nonaerosol. Lab bench required
• BSL3 Severe to fatal
diseases, but vaccines exist.
Sealed containers with
gloves, positive air flow.
• BSL 4 No vaccines or
treatment, positive-pressure
suit mandatory
10.3 Finding Patient
Zero & Tracking
Diseases
Index case-patient zero
Typhoid Mary-1900-1907 NYC
Cook, infected 51 people, nearly
30 years of isolation
HIV-1970’s Gaetan Dugas flight
attendant. Later determined that
he was one of several
responsible.
Ebola-2 year old boy in Guinea
died 12/2/2013 bitten by a fruit
bat
10.4 Microorganisms
in the Hospital
Hospital-acquired infections
(HAI), nosocomial
In U.S. 1.7 million/year, 99,000
deaths
Ventilator-associated pneumonia
UTI
Staphylococcus aureus
Methicillin resistant Staph.
aureus (MRSA)
Tuberculosis
Legionnaires’ disease
Hospital-acquired pneumonia
(HAP)-most common cause of
death
10.4 Chain of
Transmission
• Gram-negative resistant
bacteria can survive a long
time on surfaces.
• Enter body through wounds
and devices.
• Airborne: Legionella, TB,
rubeola & varicella viruses.
• Poor sanitation practices by
medical personnel is a
major cause of infection.
• All medical personnel must
follow proper sanitation
protocols including:
washing, sterilization and
personal protection
equipment (PPE).
10.5 Descriptive
Epidemiology
Calculation of risk factors based
upon data; time, place & people.
• Age
• Education
• Socioeconomic status
• Availability of health services
• Race
• Gender
• Drug abuse
• Sexual promiscuity
• Diet
• Exercise
10.5 Analytical
Epidemiology
Statistical inferences
based upon causes of
disease in populations
using sampling.
Focuses on genetic and
environmental factors
that cause disease.
10.5 Experimental
Epidemiology
Uses an experimental model
to confirm causal relationship
suggested by observational
studies.
Three case types:
1. Randomized control trial
New medicine, drug testing
2. Field trial
High risk groups
3. Community trial
Social diseases
10.5 Public Health
Local governmental
programs to promote good
health.
Focus on prevention of
disease.
• Hygiene
• Breastfeeding
• Diet
• Exercise
• Vaccination
• Planned parenthood
• Drug abuse rehabilitation
10.5 Global Health
Epidemiological, medical,
economic & political
approaches.
• World Health Organization
(WHO)
• UNICEF
• World Food Programme
(WPF)
• United Nations (UN)
• World Bank
• Doctors Without Borders
10.5 Emerging and
Reemerging
Diseases
Incidence increase in the last
20 years.
12% of all human pathogens.
• SARS
• HIV/AIDS
• Influenza
• West Nile
• Lyme disease
• Tuberculosis
• Ebola
• Zika
10.5 Biological
Weapons
Biological Warfare (BW)
Banned by 1972 Biological
Weapons Convention
• Smallpox
• Plague
• Tularemia
• Anthrax
• Brucellosis
• Botulism
10.5 Technology &
New Infectious
Agents
•
Molecular Techniques are
much faster and more
accurate at identifying
diseases.
•
Treatment development and
communication have
accelerated.
•
Overpopulation, industrial
agriculture and ecosystem
destruction are causing more
diseases.
•
Modern transportation
greatly accelerates the scope
and spread of diseases
worldwide.
10.5 Current
Pandemics
Influenza
• 3 Pandemics in 20th century
killed tens of millions
• 1918-1919 Spanish Flu 50-100
million deaths
• 1996-2008 Avian Flu (H5N1)
700 cases 60% mortality rate
• 2009-2010 Swine Flu (H1N1)
17,000 deaths
HIV/AIDS 1981-today, about 70
million infected and 35 million
dead
Ebola 2013-2016, over 28,000
infected and 11,000 deaths
Zika 2015-2016, 1.5 million
infected, 3,500 microcephaly