Transcript Occupational Infections

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By M.H.Davari MD
OCCUPATIONAL INFECTIONS
 Occupational
infections are human diseases caused
by work-associated exposure to microbial agents.
 Occupational and non-occupational infections are the
same, except:

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identification of the source of exposure
epidemiologic control
prevention.
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TUBERCULOSIS
 Transmission:
Airborne
 The bacilli may lead to:
1.
2.
latent tuberculosis infection (LTBI)
tuberculosis disease (TB)
 Staffs
of laboratories and necropsy rooms are 100
and 200 times more likely than the general public to
developtuberculosis.
 Other high-prevalence work environments:
hospitals, longterm care facilities, and dialysis centers
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Bacilli exists in: gastric fluid, CSF, urine, sputum, and tissue
specimens harboring active lesions.
 TB may be activated at any time, and cause acute pulmonary
or systemic disease.
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Diagnostic tests:
1. PPD
2. QuantiFERON-TB
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The incubation period is 4-12 weeks, and infection usually
remains subclinical without active disease, but PPD is positive.

PPD: Purified protein derivation
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1. PPD

Occupational periodic PPD in:
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Contact with infected patients
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contact with infected primates or cattle (e.g.,
veterinarians, zoo keepers, primate handlers)
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POSITIVE PPD:

5mm is (+) in:
Close contacts of infectious patients
 immunosuppressed patients:
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organ recipients
 known or suspected HIV infection.
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10mm is (+) in:
high-risk occupational groups
 immigrants from high prevalence areas
 Alcoholics
 IV Drug abusers
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No risk factors and low prevalence: 15 mm or more.
 PPD may be negative in: measles, Hodgkin disease,
sarcoidosis, or immunosuppressive states.
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Prophylaxis in a positive PPD:
 Newly infected, including recent converters (within 2 years)
 Household contacts of active cases
 Abnormal CXR consistent with TB (or prior active disease),
with inadequate past therapy
 Persons whose reactivation may have public health
consequences (e.g., school teachers).
 AIDS or HIV+.
 Silicosis
 IDDM
 Hematologic or reticuloendothelial cancer
 Chronic undernutrition
 Ileal bypass
 Renal failure requiring dialysis
 History of prolonged immunosuppressive therapy, as well
as IDUs.
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 All reactors younger than 35 years of age
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Before starting prophylaxis, a CXR is taken on all skin test
reactors. Any abnormalities should be thoroughly evaluated
for active disease.
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There are 4 accepted regimens, Each has:
1. initial 2 months phase
2. followed by continuation phase of 4 or 7 months.
Isoniazid and Rifampicin are the 2 most powerful anti-TB drugs
included in the regimen in most circumstances.
 In Person that prophylactic AB is contraindicated: serial CXR
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2. QUANTIFERON-TB
Recently, the QuantiFERON-TB Gold test has been
approved for use instead of PPD, for diagnosing both
LTBI and TB infections.
 uses freshly heparinized whole blood to detect
interferon-y from individuals sensitized to tuberculin
proteins.
1. more sensitive
2. equally specific
3. needs only one visit and is easier than PPD.
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Persons with known contact with a patient and unknown PPD
status should be PPD tested immediately, and then after 8-12
weeks.
 If conversion occurs, physical examination and CXR are
needed.
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HEPATITIS B
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1.
2.
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most frequent (10 times) among health care,
laboratory, and public safety workers (before vaccine).
Fulminant hepatitis
Chronic carrier states
o Cirrhosis & Liver cancer
The virus exists in: Blood, CSF, synovial, pleural,
peritoneal, pericardial, amniotic fluids, semen and
vaginal secretions.
Viral titers in urine, feces, tears, and saliva are low.
IV drug abuse is most important transmission
Sexual and maternal-child transmissions are alternative
modes of transmission.
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Needlestick: 30% transmission.
HBV: 1 month on dried surfaces.
Pre placement :
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HBS Ag. HBS Ab. HCV Ab
The usual schedule for vaccination: 0, 1, and 6 months.
High-risk workers in some countries: Accelerated
schedule at 0, 1, and 3 weeks and a final 12 months
dose.
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○
Vaccine Protection:
At birth: Highly protective
○ 40 y/o: 90%
○ 60 y/o: 75%
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Those who develop antibodies, lose them over time,
although they remain protected.
We should check for HBsAb 4 weeks to 6 months after
primary series.
If HBsAb is negative:
1 additional dose: 15-25% Ab Protection
○ 3 additional doses (totally 6 doses): 30-50% Ab Protection
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No Ab after 6 total doses: Changing positions at work
not involving blood or blood products.
Position change not possible: Vaccination with Merck
Recombivax HB for hemodialysis patients or 2 doses of
the Engerix-B vaccine.
More than 6 months past vaccination and HBsAb(-) 
One additional dose of vaccine
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HEPATITIS C
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Routes of transmission: Blood transfusion, IV drug use,
sexual or household exposures, and sometimes,
bloodborne pathogen transmission.
Needlestick: 1.8%
Diagnosis:
I.
II.
III.
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(EIA): 97% sensitivity within 6-8 weeks of exposure
Positive EIA tests: Confirmatory testing with highly
sensitive RT-PCR assays for HCV RNA.
RIBA (recombinant immunoblot assay): If EIA was pos. and
RT-PCR was neg.
Chronic carriers recently treated:
1. parenteral peg-interferon-alfa
2. combined with oral ribavirin.
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Exposure to knowen HCV positive blood:
1.
Test HCV RNA 2-4 week later
2.
Post exposure prophylaxy (some study)
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HIV
Occupational HIV transmission have declined:
 Antiretroviral agents in HIV Pos. patients
 Post exposure prophylaxy (PEP)
 PEP:
 To reduce drug toxicity  used only in high-risk
injuries.
 Multiple drugs are used when:
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Injuries involve larger amounts of blood (large-bore needles,
deep punctures, and visible blood on devices, needles used in
patients' arteries or veins).
 When higher concentrations of virus are suspected (e.g.,
AIDS patients, acute seroconversions, high viral loads, and
concentrated virus in special laboratory situations).
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1.
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If the source is unknown or has an unknown HIV
status, PEP generally is not warranted.
If the source is known case:
A.
B.
HIV PEP usually constitutes a 4-week course of treatment,
and we should monitor for side effects in this period,
specially the first 3 days.
HIV tests: Baseline, 6 weeks, 3 months, and 6 months.
Also 12 months if the source is coinfected with HIV and
HCV, or the individual is HCV positive.
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TRAVEL
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2.
Some lllnesses contracted during travel are specific to
the destination, such as malaria or hepatitis A.
Few vaccinations are currently required for entry into
some countries.
There is the larger number of vaccine-preventable
diseases for which vaccinations are not required.
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HEPATITIS A
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Presentation:
o Younger than 6 yr: asymptomatic
o Adults: fever, malease, juandice(lost 27 work day)
Vaccination prior to travel to Mexico, the Caribbean, and all
the other countries where food and water are less than
optimal is important.
1. The vaccine is both safe and effective, protection rates of
80-96% by 2 weeks and almost 100% protection by week 4.
o Second dose: 6-12 months after the first, which provides
long-term protection.
2. IG :less protective, Hepatitis A
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where vaccination is contraindicated
o where travel is imminent,
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RABIES
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Rabies poses a hazard in countries where animals are
not vaccinated routinely and where dogs are the most
frequent hazard.
Young children, hikers, and long-term travelers are the
groups where pre-exposure vaccination should be
considered.
The 3-dose pre-exposure vaccination series is
administered at 0, 7, and 21-28 days.
Post exposure: IG + vaccine (5 dose)
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MENINGOCOCCAL DISEASE
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Meningococcal meningitis and bacteremia caused by
Neisseria meningitidis is endemic in parts of subSaharan
Africa during the dry season.
Vaccination for travelers with close contact with local
population is recommended and required for those
traveling to Saudi Arabia for the Hajj.
2 vaccines are used in US. The older polysaccharide
vaccine protects for only 3 years. The newer conjugate
vaccine provides longer immunity and is used currently
for adolescents.
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MALARIA
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Those from nonendemic countries :
o severe illness
o developing symptoms many months after returning
from malarious regions.
4 types of malaria: Plasmodium falciparum, P. vivax, P.
ovale, and P. malariae.
P. falciparum is the most serious form and has
developed resistance in many areas of the world.
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RECOMMENDED TRAVEL VACCINATIONS
MALARIA
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nonresistant areas for P. falciparum (generally in
Central America and the Middle East):
chloroquine or hydroxychloroquine can be used.
o Chloroquine is taken weekly beginning 1 week before
entering, weekly during travel, and for 4 weeks after leaving
the malarious area.
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If chloroquine resistance exists (Southeast Asia, India,
Africa, and South America), other forms of malaria
prophylaxis :
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mefloquine, doxycycline, and atovaquone-proguanil.
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RECOMMENDED TRAVEL VACCINATIONS
MALARIA
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Mefloquine :
o associated with bad dreams, anxiety, depression,
psychosis, a lowered seizure threshold, and cardiac
conduction abnormalities.
o This drug is taken once a week in a schedule similar
to chloroquine.
Doxycycline:
o photosensitivity, gastrointestinal disorders, rash, and
diarrhea.
o This is taken once a day, 1-2 days before entering and
daily continuing up to 4 weeks after leaving the
malarious area.
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RECOMMENDED TRAVEL VACCINATIONS
MALARIA
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Atovaquone-proguanil :
o newest agent with few adverse effects that include
abdominal pain, nausea, vomiting, diarrhea,
headache, elevated transaminases, and pruritus.
o Usage: Daily, 1 day before entering and continuing
up to 7 days after leaving the malarious region.
Reduce mosquito bites: Use of an effective DEETcontaining repellent on exposed skin (avoiding the eyes
and mouth), mosquito netting, treatment of clothing
and mosquito netting with permethrin, and avoidance
of outdoor activity during the evening hours.
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TRAVELER'S DIARRHEA (TD)
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Traveler's diarrhea (TD)’s a common problem for travel
to areas with less than optimal food and sanitation.
Affects up to 30-70% of travelers during the first 2
weeks of travel.
Causes:
1.
Noninfectious: Jet lag and changes in diet
2. Infections: (ETEC), Campylobacter, Salmonella,
Shigella, enteroaggregative E. coli, and other
bacterias, and viruses like norovirus and rotavirus.
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RECOMMENDED TRAVEL VACCINATIONS
TRAVELER'S DIARRHEA (TD)
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Treatment :
1. uncomplicated :single dose of 750-1000 mg from
quinolone for diarrhea
2. more severe forms: 3-day course for or rifaximin
(200mg tid for 3 days).
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Because of quinolone-resistant Campylobacter in
Thailand and India, use of azithromycin as a backup
should be considered.
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