Transcript Lecture 5 Powerpoint presentation

MKH 1323 Occupational Health
and Disease Management
Lecture 5
Dr. Zainura Z. Noor
OCCUPATIONAL DISEASES AND
INFECTIONS: PART III
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Introduction
• Certain work activities are associated with an increased
risk of contracting infections due to contact with large
numbers of people with infections.
• Those activities includes those who are:
– Working in health care field;
– Travelling to endemic areas during the course of their work.
• Infections can be caused by:
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–
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Viruses;
Bacteria;
Rickettsiae;
Parasites.
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Blood-borne Infections Background
• The main occupational blood-borne infections of concern are:
– Hepatitis B, C;
– HIV;
– AIDS.
• Health-care workers have been infected through work
activities, usually inadvertent contact with large amount of
blood – often involving needlestick injuries or through skin
lesions or abrasions.
• Prevention includes:
– Care in the use of sharp instruments;
– The use of gloves for surgical procedures;
– Safe disposal of sharp instruments in well-designed strong containers
that are not overfilled;
– Attention to safe systems at work.
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Blood-borne Infections – Hepatitis B
• Causative organism: Hepatitis B virus.
• Can be sexually or vertically (from mother to child) transmitted.
• Prevalent in the countries in the Far East.
• Malaysia, Taiwan, Singapore and Hong Kong have an active
program of Hepatitis B immunization for the population.
• In occupational settings, most common cause is in contact with
infected blood or bodily fluid.
• Occupational groups at risk: doctors, nurses, laboratory and
research staff as well as other health-care workers.
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Blood-borne Infections – Hepatitis B
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Blood-borne Infections – Hepatitis B
• May lead to full recovery, a chronic carrier state or liver failure
and death.
• Carrier status is indicated by the presence of antigens:
Hepatitis B surface antigen (HBs) with or without e-antigen
(HBe).
• HBs and Hbe carriers are infectious carriers and those with
these antigen markers have an increased risk of chronic liver
disease and liver malignancy.
• HBs-positive but HBe-negative were thought to be of low
infective risk, but recent cases have indicated the potential for
passing infection to patients .
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Blood-borne Infections – Hepatitis B
• Hepatitis B immunoglobulin have been administered to prevent
infection soon after a needlestick injury or substantial contact
with blood from a known hepatitis B carrier or case.
• Serum or yeast-derived vaccine is genetically engineered
vaccine.
• A full course of vaccinations consists of three intramuscular
(deltoid) injections of 0.5 ml vaccine, with 1 month between the
first and second doses and 5 months between the second and
third doses. A booster dose is suggested after 5 years.
• Some individuals do not produce antibodies in spite of several
doses of vaccine.
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Blood-borne Infections – Hepatitis C
• Causative organism: Hepatitis C virus.
• Has similar features to hepatitis B.
• Can progress to chronic liver disease with an increased risk of
liver malignancy.
• Unlike hepatitis B virus, this is an RNA virus, and I does not
have the benefit of available vaccine.
• Lab confirmation of the presence of hepatitis C viral RNA
indicates infection, a risk of transmission from the performance
of exposure-prone procedures.
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Blood-borne Infections – Other Hepatitis
Viruses
• Include hepatitis A, D (delta agent) and other newly identified
viruses capable of causing liver diseases.
• Hepatitis A is food-borne and vaccine is available.
• The other hepatitis viruses are blood-borne, with NO effective
yet available.
• The occupational measures for preventing hepatitis B and HIV
also apply in preventing other blood-borne hepatitis infections.
• Unfortunately, some individuals who have been immunized
against hepatitis B are thought to be immunized against all
blood-borne infections.
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Blood-borne Infections – AIDS
• Causative organism: human immunodeficiency virus (HIV).
• HIV is an RNA virus belonging to the Lentivirus family of
retroviruses.
• It was first identified in the early 1980s, and since then several
subtypes have been described.
• Acquired through vertical transmission, unprotected sex,
sharing needles and occupationally from needlestick injury orn
splashes involving samples of infected blood.
• The risk of infection from needlestick injury is 3/1000 with a
higher risk from deep injuries with hollow-bore needles.
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Blood-borne Infections – AIDS
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Blood-borne Infections – AIDS
• Sero-conversions occurs after 6-12 weeks, and the nonprotective virus antibodies are detectable by ELIZA (enzymelinked immunosorbent assay).
• Can remain dormant with no overt clinical features, or it may
progress to clinical syndrome, AIDS which manifest as an
increased susceptibility to infection e.g. lung infection.
• There is also an increased risk of skin malignancy-Kaposi’s
sarcoma and non-Hodgkin’s lymphoma.
• Of the 40 millions cases of AIDS worldwide, there have been
just over 40 published cases of occupationally acquired HIVsero conversion.
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Blood-borne Infections – AIDS
• Treatment for AIDS:
– DRUGS: include reverse transcript inhibitors such as zidovudine
and lamivudine as well as protease inhibitors such as indinavir.
– Post-exposure prophylaxis involves the use of combination
therapy with several such drugs.
– Following a needlestick injury, and before post-exposure
prophylaxis, the individuals should be counselled on the effects of
the treatment.
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Vector-borne Infections – Malaria
• Causative organism: Plasmodium
falciparum and other species.
• Infection transmitted by mosquitoes
(Anopheles sp.).
• An endemic in in tropical and subtropical
areas such as part of Asia and Africa.
• The organism enters red blood cells and
causes haemolysis and anaemia.
• Also affects liver cells and the spleen,
leading to hepatosplenomegaly
(simultaneous enlargement of both the
liver and the spleen).
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Vector-borne Infections – Malaria
• Cerebral malaria can cause result in delirium, coma and
death.
• Occupational groups at risk include forestry workers,
agricultural advisers and temperate zone expatriates and
travellers.
• Anti-malarial tablets such as chloroquine or proguanil are
recommended for areas WITHOUT drug resistance.
• Where there is drug resistance, alternative medications
include mefloquine, doxycycline or combination of
pyrimethamine and dapsone or proguanil with chloroquine.
• Chemoprophylaxis should be started 1 week before leaving
for malarious area, and should continue 4 weeks after return.
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Vector-borne Infections – Malaria
• Drug prophylaxis is not 100% effective and all febrile illnesses
occuring within a year of return from malarious area, should
be investigated.
• Advice should be given on the possible side-effects of
medications. For instance:
– Mefloquine cause neuropsychiatrics effects;
– Doxycylcine cause photosensitisation.
• Occupational health departments should be aware of the
contraindications to the use of such medications, for instance:
– Mefloquine should be used during in the frist trimester of pregnancy;
– Proguanil affects the efficacy of anticoagulants.
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Vector-borne Infections – Lyme
Disease
• Causative organism: Borellia burgdorferi.
• Tick-borne disease that affects deer and rodents but can be
transmitted to humans.
• Occupational groups at risk are farmers and forestry workers.
• The disease manifests as skin lesions with possible
neurological or cardiac complications.
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Food- and Water-borne Infections
• Include chlolera, shigellosis, typhoid and parathyphoid fever,
and E.coli infection.
• Occupational health departments may be involved if:
– They occur in food-handler;
– When members of the workforce have to travel abroad dirng the course
of their work.
• Where a food handler is diagnosed as having enteric fever,
six consecutive negative stool samples, each obtained 1 week
apart commencing 3 weeks after completion of treatment are
recommended before return to work.
• If infection involves E.coli (0157:H7), two consecutive
negative stool samples are taken at least 48 hours apart.
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Food- and Water-borne Infections
Food- and Water-borne Infections
• If a food-handler has non-specific diarrhea and vomitting, a
minimum 48 h asymptomic period without medication is
advised before review and return to work duties.
• For travelers abroad, immunizations for food infections can be
arranged based on awareness of outbreaks of diarrhoeal
diseases in the countries which they travelled.
• Typhoid vaccine may be administered parenterally or orally
for travel to areas with recognized risk of exposure to
Salmonella typhi.
• Vaccine for cholera is less than 60% effective.
• No vaccine is available for E.coli or shigellosis.
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Infections by Droplets and Close
Contact – Tuberculosis (TB)
• Causative organism: Mycobacterium tuberculosis.
• Symptoms:
– Chronic coughs, loss of weight, night sweats and possibly haemoptysis.
• Can also affects bones and other parts of the body.
• Diagnosis by the detection of pulmonary infiltration,
cavitations of fibrosis often in the upper lung zone, via X-ray.
• Highly prevalence in developing countries especially those in
poor socioeconomic situation.
• An increased risk in AIDS patients due to their compromised
immune status.
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Infections by Droplets and Close
Contact – Tuberculosis (TB)
Infections by Droplets and Close
Contact – Tuberculosis (TB)
• Occupational groups at risk include mortuary staff,
pathologists and post-mortem room personnel.
• Agricultural workers and veritinary staff occasinally acquaire a
related infection due to Mycobacterium bavis.
• Vaccine: BCG (bacillus Calmette-Guerin).
• Treatment involves the use of drug regimes include
streptomycin, isoniazid, p-aminosalicylic acid and rifampicin..
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Infections by Droplets and Close
Contact – Meningococcal Meningitis
• Causative organism: Neisseria meningitis.
• Close occupational contact, i.e. mouth-to-mouth resuscitation
of an infected patients, poses a possibel risk to occupational
workers.
• Avoiding close contiact will reduce the likelihood of this
occuring.
• However if there is close-contact, prompt administration of
course ciproflaxacin or rifampicin is appropriate prevention.
• Rifampicin can interfere with the efficacy of oral contraceptive
pill.
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Zoonotic Infections
• Anthrax
– Causative organism: Bacillus antracis;
– Spores present in animal hides, hair, bones, fur, wool or horn where
inhale can cause pneumonic anthrax;
– Skin contacts lead to characteristic ulcerative lesions known as ‘eschar’;
– Can also present as septicaemia.
– Antibiotic treatment bu the use of penicilin.
– Occupationally acquired anthrax through the treatment of animal hides
and horns.
– Immunizations are available for workers at risks.
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Zoonotic Infections
• Orf
– Causative organism: orf (parapox) virus;
– Affects mainly birds and poultry;
– Occupational groups at risk are pet-shop keepers, farmers, taxidermists
and zoo workers;
– Symptoms: flu-like illness developing into pneumonia with fever,
headache and chest symptoms.
– Can be severe but rarely fatal;
– Diagnosis via detection of an increase antibody titres in serum’
– Treatment through tetracyclines drug.
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Zoonotic Infections
• Q Fever
– Causative organism: Coxiella burnetti;
– Affects sheep, goats and cattle;
– Can be transmitted to human via droplet infection or through direct
contact with infected meat, birth fluids or contaminated wool, straw and
raw milk;
– Occupational groups at risk are vets, farmers, laboratory personnel and
wool processors;
– Symptoms: mild influenza-like illness.
– Diagnosis via detection of a serial increase in specific antibodies;
– Treatment through tetracyclines drug;
– Prevention includes separate enclosure for calvinga nd lambing, use of
gloves aprons, etc.
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Other Infections
• Legionnaires’ Disease
– Causative organism: Legionella pneumophila;
– Affects susceptible individuals such as immunocompromised patients in
hospitals especially those with chronic pulmonary disease;
– Incubation is between 2 and 10 days, usually 3-6 days;
– Symptoms: fever, non-productive cough, headache and malaise;
– Chest X-ray will show patchy consolidation;
– Diagnosis via detection of urinary antigen;
– Treatment through Erythromycin drug;
– Occupational exposures include buildings where the bacili proliferate in
the water and spread through the ventilation or water supply system;
– Prevention includes cleaning up the ventilation, water supply and water
humidification systems, keeping water supply below 20 degree C or
above 60 degree C and hyperchlorination of water.
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Other Infections
• Methicillin-resistant Staphylococcus aureus (MRSA)
– Commensal present on the skin, nose and throat of a large proportion of
the general population;
– Does not usually pose risk to healthy inviduals but risk to
immunocompromised patients, and those with surgical or traumatic
wounds;
– Some hospitals screen staff intending to work in surgical, renal, accident
and emergency and other clinical wards for MRSA carrier state.
– Staff members with MRSA colonisation are tretaed using topical
applications such as chlorhexidine or bacitracin cream, before they are
allowed to work.
– However, MRSA has the tendency to recolonize after eradication;
– Measures such as washing hands with soap and water and the use of
alcohol-based wipe between the handling of the patients will minimize
the risk of transmitting MRSA between patients.
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In-Class Discussion
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Newly Emerging Infections
In 10 minutes, discuss among your classmates regarding the
newly emerging infections such as H1N1, SARS, Avian flu,
Norovirus, etc with respect to the occupational groups who
are at risk in getting the infections. Share your opinions and
thoughts from the discussions with others.
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THANK YOU!
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