Flashcards in Chapter 29 Deck (46):
1
What is a well adapted pathogen
one that lives in balance with its host
2
What are chronic infections
host and pathogen survive
3
Three steps of an acute infection
1. short term infection
2. rapid and dramatic onset of disease
3. host returns to good health
4
Stages of a disease
1. Infection: organism invades and colonizes host
2. Incubation period: time between infection & onset of symptoms
3. acute period: the disease at height, overt symptoms present
4. Decline period: disease symptoms subsiding
5. Convalescent period: patient returns to normal state
5
Difference between mortality and morbidity
mortality: incidence of death in a population
morbidity: incidences of diseases in a population that includes both fatal and nonfatal diseases.
6
Worldwide deaths due to infectious diseases
1. Respiratory: 31% (bacteria, viruses, fungi)
2. Diarrheal diseases 15% (bacteria virus)
3. AIDS 13% (virus)
4. Tuberculosis 15% bacterium
5. Malaria 6% (protist)
...
Others 11%
7
What is the myxoma virus
Biocontrol of rabbits in Australia
8
Steps of host-to-host transmission
1. Virulence diminishes
2. Resistance of host increases
3. Pathogen extinction may occur if host killed before transmission
4. if no host to host transmission, pathogen may remain virulent
9
What is herd immuinity
Resistance of a group to infection due to immunity of a high proportion of the group
10
What happens in herd immunity
immunized people protect nonimmunized and pathogen cannot be passed on
11
Common themes of all modes
1. escape from host
2. travel
3. entry into new host
12
Major mneans of human infectious diseases transmission
1. person to person: direct contact (hand shake, sex), indirect contact (watercup), airborne droplets (sneeze cough)
2. Vehicle: (borne to all) water, food, air, soil
3. Vector: arthopods/insects (lyme disease, malaria)
13
What is transmission facilitated by and what are the they?
Agents:
living agents: vectors
nonliving: vehicles and formites
14
What is zoonosis
disease primarily infection animals
occasionally transmitted to humans
15
know the cycles of host infection
know the cycles of host infection
16
Steps of schistosomiasis
1. Embryonated eggs each with a fully developed miracidium are passed in feces
2. snail host ingests eggs, miracidia emerge from eggs and penetrate the snail intestine
3. cercariae released from snail
4. cercariae penetrate the skin of fresh brackish water fish
5. host becomes infection by ingesting undercooked fish contain metacercariae
6. metacercariae exyst in the small intestine
7. adult in small intestine
17
Eggs developed for miracidia
sporocysts -> rediae -> cercariae
18
what are common source epidemics
usually from water and food contamination
cholera
19
examples of host-to-host epidemics
influenza
chickenpox
20
There is also cyclical and seasonal diseases
There is also cyclical and seasonal diseases
21
what are carriers
infected individuals with no/mild symptoms.
potential sources of infections
indiviuduals in incubation period
22
what are ways carriers can be identified
culture and immunoassays
23
What is a basic reproduction number
R0, and it is number of expected secondary cases from each single case, different infectious diseases have different R0
24
Know table
know reproduction table
25
Controls against common vehicles
common: food, water, air
food laws, water purification, but airborne pathogens are difficult to control
26
Controls against major reservoirs
domestic animal reservoirs:
can be immunized or destroyed
wild:
elimination is impossible
insect:
insecticides and screens
27
Controls directed against transmission
immunization
i.e. smallpox, tetanus
isolation, quarantine, surveillance
28
What is the only pathogen that has been eradicated
smallpox, polio is a goal but not completely yet
29
AFRICA CHART
AFRICA CHARt
30
what are diseases that suddenly become prevalent
emergent
31
reemerging diseases are
diseases that become prevalent after being under control
32
EMERGING AND REEMERGING DISEASES TABLE
EMERGING AND REEMERGING DISEASES TABLE
33
name some emergent factors
human demographics i.e. urban vs rural
changes in land use, i.e residential deforestation
bulk processing and central distribution i.e. food and beverages
international travel: i.e. airline (ebola)
Microbial adapation and change i.e. RNA VIRUSES
Breakdown of public health measures: i.e. cholera
Natural disasters
climate change: i.e. mosquitoes are moving northward
34
cholera pandemic
cholera: causes severe waterloss diarrhea that occurs due to ingestion of contaminated water (usually occurs in developing countries)
cholera was endemic: AFrica, SEA, Indian subcont, CA and SA
35
how was cholera an epidemic
sewage treatement brokedown (flood, hurricane etc)
36
influenza pandemic
occurs every 10-40 years that is casued by major change in genome
37
ways influenza has major changes in genome
antigenic drifty: gene mutation (minor change)
antigenic shift: gene reassortment (major)
38
what is the 2009 pandemic
swine flu, example of gene reassortment
39
What is microbial (biological) warfare
use of bilogical agents to kill
40
what is biological warfare break
against the Geneva Conventions
41
Characteristics of microbial weapons
1. easy to produce and deliver
2. safe for use by the offensive soldiers
3. able to incapacitate or kill individuals
42
small pox details (as a weapon)
small pox: mortality rate 30% or higher.
while vaccine exists, efficacy against weapons-grade is untested
43
anthrax details (as a weapon)
easy to culture, and identify on petri plates w/ agar
contains endospores
1. can store indefinitely
2. easy aerosolization
3. remain in environment for long time
44
what are the three forms of anthrax disease and its mortality rates
1. cutaneous (skin) 20% in untreated
2. gastroinstestinal 50%
3. inhalation close to 100%
45
characteristics of weapons grade anthrax
resistance to many antibiotics, vaccines should still provide some protection.
enhanced for maximal dispersal (smaller and remain in air longer and travel farther)
more scattered
46