Transcript Biological hazards

Infection control
Biological
Hazards
Infectious Diseases
Bacteria
Parasites
Viruses
Prions
Fungi
Parasites
INFECTIOUS DISEASE
PROCESS
• INFECTION:
presence of
microorganisms in the
body that cause
disease
Staph. infection
• NORMAL FLORA:
microbes that are
found in/on everyone.
Many prevent disease
Normal flora of mouth
6 Links to the Chain of
Infection
Portal
of Entry
Susceptible
Host
Causative
Agent
Reservoir
Mode of
Transmission
• Control by stopping one
link in chain
Clinical stages of an
Infectious Disease
Infection
Prodromal period
Incubation
Acute period
Decline period
Convalescence
Causative Agents
• Bacteria
•Viruses
•Hot tub rash
Protozoa
Giardia
•
•Glandular fever
•Fungi
•Helminthes
Parasites
Internal
– Helminths (worms)
 Tape worms
 Nematodes
– Protozoa


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
Toxoplasma
Giardia
Histamoeba
Cryptospiridium
External
 Insects
– Bed Bugs
– flees

Lice
Bedbug
Bedbug
Feeding
In bed

bites
Fleas
Fleas are small, wingless bloodsucking insects (order
Siphonaptera) with a characteristic jumping movement.
 The most important species are the rat flea, the human
flea and the cat flea
 Their bites can cause irritation, serious discomfort and
loss of blood.
 The rat flea is important as a vector of bubonic plague
and flea-borne typhus.
 Cat fleas incidentally transmit tapeworms.

LICE
Lice are small bloodsucking insects that
live on the skin of mammals and birds.
 Three species of lice have adapted
themselves to humans:

– the head louse (Pediculus humanus capitis),
– the body louse (Pediculus humanus) and
– the crab or pubic louse (Pthirus pubis)
Characteristics of causative
agents
• Dose
•Small : TB
•Large : Leagonnella
• Pathogenicity
•Strong : TB, Bird flue
•Week: Common cold
Methods by which bacteria cause
disease

Adhesion. Many bacteria must first bind to host cell surfaces.

Colonization. Some virulent bacteria produce special proteins that allow them to colonize parts
of the host body. Helicobacter pylori is able to survive in the acidic environment of the human
stomach by producing the enzyme urease. Colonization of the stomach lining by this bacterium
can lead to Gastric ulcer and cancer. The virulence of various strains of Helicobacter pylori tends
to correlate with the level of production of urease.
Invasion. Some virulent bacteria produce proteins that either disrupt host cell membranes or
stimulate endocytosis into host cells.

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Immune response inhibitors. Many bacteria produce virulence factors that inhibit the host's
immune system defenses. For example, a common bacterial strategy is to produce proteins that
bind host antibodies. The polysaccharide capsule of Streptococcus pneumoniae inhibits
phagocytosis of the bacterium by host immune cells.

Toxins. Many virulence factors are proteins made by bacteria that poison host cells and cause
tissue damage. For example, there are many food poisoning toxins produced by bacteria that can
contaminate human foods.
Reservoirs
•
Animals
• Insects
• Rodents
• Shell Fish
Reservoirs
•
Environment
Machinery & Equipment
Environmental Surfaces
 Food
Human Source /
Reservoir of Infection
Active carrier
Convalescent carrier
Healthy Carrier
Incubatory carrier
Casual or
Chronic
Modes of Transmission
• Contact
•(Direct and
•Indirect)
•Airborne
•Vector-Borne
• Solid material
CONTACT
DIRECT: immediate transmission
•
Person-to-person
•
Actual physical contact between
source and person
INDIRECT CONTACT:
•
Agent contaminate indirect
object
•
Droplets spread (large particles
that rapidly settle out on
horizontal surfaces – usually
within 3 feet of source)
Direct transmission
Staphylococcal infections
Staphylococcus
Ringworm
AIRBORNE

Organisms contained within droplet nuclei or
dust particles (i.e. droplet nuclei of
tuberculosis
•
Suspended in air for extended periods, may
be spread through ventilation systems
Diseases transmitted By Air
Bacterial
Tuberculosis
Fungi
Anthrax
Histoplasma
Legonella
Candida
Q – Fever
Neisseria
Psittacosis
Streptococcus
Clamydia
Parasites
Toxoplasmosis
Viruses
Influenza
Measles
Chickenpox
Mumps
Colds
VECTOR-BORN
• External vector-born transmission
•mechanical transfer of microbes on external
appendages (e.g. feet of flies)
• Harbored by Vector-born
•Inside vector
• Ross river virus
•West nile virus
Hendra virus
Hendra virus is a virus carried by
fruit bats that inhabit Australia,
Papua New Guinea, and
surrounding islands.
 Rarely, Hendra virus spreads
from fruit bats to horses, causing
severe disease, and can then
spread to people who are in
close contact with infected
horses.
 Four of the seven people who
are known to have been infected
(at the time of writing) have

died.
Figure 1. Distribution of flying foxes in
Australia
Australian local vector-borne
diseases

Mosquito borne
– Ross River virus, Barmah Forest virus and Murray
Valley encephalitis virus.
– Possible Future Threats
 Chikungunya virus: a re-emerging threat
 Dengue fever and Malaria

Tick borne
– Australian tick typhus: Rickettsia australis, severe
headache and conjunctivitis. Reservoir is in rodents
and marsupials.
– Flinders Island Spotted Fever: caused by
rickettsiae R. honei,
Tick Borne
Lyme
Disease
PORTAL OF ENTRY

The path by which an
infectious agent
enters the susceptible
host
• Respiratory Tract
• Genitourinary Tract
• Gastrointestinal Tract (Gut)
• Skin/Mucous Membrane (eye)
• Trasplacental (fetus from mother)
• via blood
Respiratory Tract
Portal of Entry
TB
 Flue
 Bronchitis
 Common Cold
 Legionnaires' Disease
 Whooping Cough

Control
Personal Hygiene
 Sanitation
 Vaccination
 Passive Immunity
 Active Immunity
 Antibiotics
 Isolation
 Quarantine

SUSCEPTIBLE HOST
A person or animal lacking
effective resistance to a
particular pathogenic
agent
Increase Resistance

Good General Health
– Nutrition
– Well being
Vaccinations
 Personal Hygiene
 Sanitation

Good General Heath

Nutrition
– Needed for immune system
– Plenty of energy
– Vitamins
dieing from infection
 A, B group, C
– Minerals
 Iodine, Iron, Zink,
–Dieing from CVD

Dieting
– Loosing weight lowers immunity
– Less eating does not just reduce fat
– More chance of dieing from infection
Five Food Groups
Bread &Cereals
 Fruit & veg.
 Dairy
 Meat
 Fats

Healthy Diet Pyramid
Good General Heath

Factors that reduce Immunity
– Stress
– Cold
– Flue
– AIDs
– Drugs

But even a good may not protect against
all infections
Vaccination
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Ensuring the immunity of workers to infections
or diseases caused by relevant infectious agents
is an essential component of any firms occupational
health program, to accomplish fundamental legal and
moral duties:
– Protection of workers from risk of the work place
Tetanus
Hepatitis A, B
TB
Flue
Childhood vaccines
– Age
– immigrants
Hygiene

Wash hands
– ASAP
– Stops transfer
to mouth
– Stops transfer
to environment
(door handles
etc. )
Hygiene

Wash and disinfect
cuts and scratches
– Keep wounds covered

Wear face masks
– Minimise inhaling dust
and pathogens
Chemical Methods of Microbial
Control

Disinfectants
– Used on non-living surfaces

Antiseptics
– Used on living surfaces

Antibiotics
– Used internally
– Not much use for viruses and fungi
Antibiotic resistance
–Betadine
Chemical Methods of Microbial
Control

Effective disinfection
– Type of organisms
– Chemical used
– Proper dilution
– Cleanliness
– Contact time
Floor disinfection
Evaluating a Disinfectant

Phenol coefficient test
– Compared activity to phenol
Exposure to Hepatitis B virus

Contact with HB-positive blood or body
fluid
Meningococcus

Direct contact with respiratory secretions
Skin Infections and
Diseases
Scabies and Tinea Versicolor
Scabies
 Female
mites burrows into
the skin where she lays
eggs
 Skin-skin contact
 Clothing, bedding, towels
 Inflammatory elevation of
the skin (red papules)
Scabies
S/S
- intense itching
- skin rashes
- produces allergic reaction (eggs)
- scratching may cause secondary
infection
 Tx
- Topical medications all over the
body

Tinea Versicolor
 Skin
infection caused
by a yeast
 Warm and humid
environment
Tinea Versicolor

S/S
- oval or irregularly shaped spots
- pale, dark tan, or pink in color
- sharp border
- itching, worsens with heating
and sweating

Tx
- Topical antifungal medications
Ringworm
Ringworm
 Fungal
infection…not a worm!
 Skin-skin contact
 Ring-shaped, scaly itching
patches on the skin
Ringworm
S/S
- red raised itchy
patches with defined
edges, lighter in the
center
- take an appearance
of a ring
 Tx
- topical antifungal
drugs

Impetigo
Impetigo
 Superficial
skin infection
 Bacterial…Staphylococcus
or Streptococcus
 Spread w/ direct contact
w/ lesions , dressings
 Thick, yellow crust
(commonly on the face)
Impetigo
- one or more pimplelike lesions surrounded
by reddened skin
- lesions fill w/ pus and
later form a thick crust
- itching
Infected Wounds
Infected Wounds
 Wound:
break in the
structure caused by
an external agent
 Chronic open sores
become infected
Infected Wounds

-
swelling
pain
fever w/ infection
bleeding or pus
foul smell
Hookworm? Traveling parasite
Hookworm
 Cutaneous
larva migrans
 Parasitic larvae found in dog
and cat feces penetrate the
outer layers of the skin and
creep around underneath the
skin
Hookworm
 S/S
- red itching eruption
- serpentine track
- painful
 Tx
- Albendazole
Other interesting stories…
Leishmaniasis
???