Biological Occupational Hazards
INFECTIOUS DISEASE
Workers are at risk of infection if the are exposed
to sauces of infection in the performance of their duties.
The risk if infection is greater if workers have
direct contact with a large number of individual humans ,animals or animal
products. In some cases workers who have little contact with others are
at risk via air borne infections transmitted through air conditioning systems
Work Related Infections
|
Means of Infection
|
Type of Work
|
Infections
|
Close contact with people.
(via air and contact) |
Sales, Teaching, Customer service, Banking |
TB, Meningitis, Air borne viruses, Measles, Mumps, |
Contact with human skin
(Direct contact) |
Hair dresser, Nurse, Masseur, Chiropodist, Chiropractor |
Staph, Strep. Herpes, Ringworm, Warts |
Contact with fecal pollution
(Indirect contact) |
Child care, Aged care, Swimming Pool, Handicapped care |
Hep A, Gastric infections, Trachoma |
| Blood contact via Cuts and Pricks (Direct contact) |
Nursing, Health care, Dental work. Mortuary. |
HIV, Hep. B and C |
| Contact with Animals Dust, Hides, (Contact ) |
Abattoir workers, Tanners, Farm hands, Veterinary work |
Anthrax, Q-fever, TB Toxoplasmosis, Ringworm |
Handling Animals
(Direct contact & vectors) |
Farmers, Rangers, Trainers, Strappers, Farriers, |
Tick borne diseases, Encephalitis, Meliodosis, Glanders. Cat-scratch
disease |
Birds, Bird droppings.
(Indirect contact) |
Vets, Aviary workers, Cleaners |
Psittacosis, Sporotrichosis,
Crytococosis. Histoplasmosis |
Animal flesh
(Direct contact) |
Abattoir workers, Butchers,
Veterinary, Pet shop employees |
Brucelosis , TB, Mad Cow Disease |
Air Conditioning air
(Air transmission) |
Office , Hospital, Hotel, Exhibition workers |
TB, Legionnaires Disease, Histoplasmosis |
| Garden Plants, Mulch, via pricks and scratches, Cuts |
Gardeners, Farmers, Out door cleaners |
Sporotrichosis, Staph, Pseudomonas, Tetanus |
Eating Work supplied Food
(Indirect Contact) |
Hotel , Resort , Hospital, Hostel, Ship, Oil rig, Airline and Isolated
workers |
Food borne poisoning and infections |
Control
Many of the above infections can be controlled by vaccination. Some
should be received by all citizens (measles, mumps, TB, polio) flue,
but some are only need by particular types of workers (e.g.. anthrax, brucellosis,
Hep A and B and meningitides)
Childhood Diseases: Diseases like measles, mumps and diphtheria are
often regarded as childhood diseases. This is because before vaccinations
wide spread children caught these diseases when they first came in contact
with them and there were many opportunities.
But it was not because of the age that they got infected. These days
with wide spread vaccination it is possible for an unvaccinated person
to go through life without meeting a carrier. However if such a person
meets a carrier. (who may have no signs of infection) they will easily
become infected. In many cases these diseases in adults is more serious
than in children.
Employees who come in contact with large numbers of clients have a
much greater chance of contact with all kinds of carriers. Measles is one
of the most underrated diseases around and can lead to serious complications
and death.
Agents of Infectious Disease
Viruses
e.g..
Hepatitis
A, B and C, Flue,
Mumps,
Measles,
AIDs, Colds,
Glandular
fevers (infectious mononucleosis),
Post
Viral Fatigue Syndrome, Herpes, Rabies, Equine encephalitis.
Bacteria:
Cocci
Bacilli
e.g.. Anthrax, TB, Salmonella,
Cholera and Typhoid, Tetanus, Brucellosis
Spirochaetes
Mycoplasmas
e.g.. Mad Cow Disease?
Rickettsiae,
Chlamydiae
Fungi
Parasites:
Protozoa
Helminthes
Arthropods
Mechanisms of Infections
1. Portal of Entry
= Process by which pathogen
enters body and eventually causes disease
Does not always reflect site of infection
Types of Portal of Entry
Penetration
Direct
Contact:
Ingestion
Inhalation
a) Penetration (Disruption
of skin)
Wounds, abrasion, burns
Surgery
Infection (e.g. chickenpox, Hook worm)
Animal bite, ticks insects
b) Direct Contact
Transmission
to mucous membranes from infected tissue or secretion without there being
a break in barriers
STDs: syphilis, gonorrhea, chlamydia, herpes, HIV…
c) Ingestion
Very efficient Portal of Entry for humans
and Agents must survive low pH, enzymes, peristalsis and competition with
normal bacteria
e.g. Cholera, typhoid fever, dysentery, traveler's diarrhea, food poisoning,
Hep. A,
d) Inhalation
Tough Portal of Entry b/c lots of
defenses in RT
Bacterial
pneumonia
Meningitis
and sepsis
TB
Viruses that cause measles, mumps, chicken pox, influenza, common cold
2. Source
Endogenous:
Own flora => opportunistic infection
Exogenous:
Other person, incl. infection via body fluids and secretions
Animal
Water, food, soil, objects (needles, fomites)
Carriers
Active carriers
People who have obvious symptoms of the infection
Incubatory carriers
People who have become infected but not developed symptoms
Convalescent Carriers
People who no longer have symptoms of the infection and are
still recovering
Silent Carriers
People who have no signs of infection. They may never have knowingly had
the disease
This condition can be chronic or transitory
Reservoirs
of infection
Carriers
As above
Fomites
Inanimate objects like bedding, equipment, money, clothing
Vectors
Small animals such as cockroaches, flies, rodents, ticks and mosquitoes.
Animals
All kinds of animals and birds (mainly carriers of zoonoses)
4. Disease Course
Incubation Stage:
Pathogen begins replicating; no symptoms; short or long
Prodromal Stage:
Initial symptoms, but vague (e.g. malaise)
Acute Stage (identifiable
symptoms):
Rapid proliferation and spread of pathogen; toxic byproducts, lysis, immune
response and inflammation
Convalescent Stage:
Containment, elimination, repair
Resolution:
Total elimination; no residual symptoms
Exceptions to Classic Disease Course
Chronic Infections: continuous or sporadic symptoms
without convalescent stage
Subclinical or Subacute: infection to resolution without
apparent symptoms
Insidious: prolonged prodromal
Fulminant: abrupt onset of symptoms; small or no prodrome
(e.g. cholera)