1 Occupational Infections - PowerPoint Presentation

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Occupational Infections

By

M.H.Davari

MD

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Occupational Infections

Occupational infections are human diseases caused by

work-associated exposure

to microbial agents.

Occupational and non-occupational infections are the same, except:identification of the source of exposure

epidemiologic controlprevention.

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Transmission:

Airborne

The bacilli may lead to:

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

TUBERCULOSIS

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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.

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:

Contact with infected patientscontact 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 patientsimmunosuppressed patients:organ recipients

known or suspected HIV infection.10mm is (+) in:

high-risk

occupational

groups

immigrants

from

high prevalence

areasAlcoholicsIV Drug abusers

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 casesAbnormal 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 cancerChronic undernutrition

Ileal

bypass

Renal failure

requiring dialysis

History of

prolonged immunosuppressive

therapy, as well as IDUs.

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. There are 4 accepted regimens, Each has:initial

2 months phase 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.more sensitive

equally specific

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

most frequent (10 times)

among

health care

, laboratory

, and public safety workers (before vaccine).

Fulminant

hepatitis

Chronic carrier

states

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

m

aternal-child

transmissions are alternative modes of transmission.

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Needlestick

:

30% transmission. HBV: 1 month on dried surfaces.

Pre placement :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.13

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Vaccine Protection:

At

birth: Highly protective

40 y/o: 90%

60 y/o: 75

%

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 15

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HEPATITIS C

Routes of transmission:

Blood transfusion, IV drug use

, sexual or household exposures, and sometimes,

bloodborne pathogen transmission.

Needlestick: 1.8%

Diagnosis:

(

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:

parenteral

peg-interferon-

alfa

combined with

oral ribavirin

.

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Exposure

to

knowen

HCV positive blood:Test HCV RNA 2-4 week laterPost exposure prophylaxy

(some study)17

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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: 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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If the source is

unknown

or has an

unknown HIV

status, PEP generally is not warranted.If the source is known case:

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

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

Presentation

:

Younger than 6 yr

: asymptomaticAdults: 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. Second dose:

6-12 months

after the first, which provides

long-term protection

.

2.

IG

:less protective, Hepatitis A

where vaccination

is contraindicated

where

travel is imminent

,

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Rabies

Rabies poses a hazard in countries where

an

i

mals

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

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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Those from

nonendemic

countries :

severe illness

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. 24

Malaria

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RECOMMENDED TRAVEL VACCINATIONS

nonresistant

areas for

P. falciparum

(generally in Central America and the Middle East):

chloroquine or hydroxychloroquine can be used.

Chloroquine

is taken

weekly

beginning

1 week before entering, weekly during travel, and for 4 weeks after leaving the malarious area.

If chloroquine resistance exists (Southeast Asia, India, Africa, and

South America

),

other forms

of malaria prophylaxis :

mefloquine

,

doxycycline

, and

atovaquone-proguanil

.

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Malaria

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RECOMMENDED TRAVEL VACCINATIONS

Mefloquine

:

associated with

bad dreams, anxiety, depression, psychosis, a lowered seizure threshold, and cardiac conduction abnormalities.

This drug is taken once a week in a schedule

similar

to

chloroquine

.

Doxycycline

:photosensitivity, gastrointestinal disorders, rash, and diarrhea.

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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Malaria

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RECOMMENDED TRAVEL VACCINATIONS

Atovaquone-proguanil

:

newest agent with

few adverse effects that include abdominal pain, nausea, vomiting, diarrhea, headache, elevated transaminases

, and pruritus.

Usage:

Daily, 1 day before entering

and continuing

up to 7 days

after

leaving

the malarious region. Reduce mosquito bites: Use of an effective

DEET-containing 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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Malaria

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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:

Noninfectious: Jet lag and changes in

diet

Infections

:

(ETEC), Campylobacter, Salmonella,

Shigella

, enteroaggregative E. coli

, and other bacterias, and viruses like norovirus and rotavirus.

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Traveler's Diarrhea (TD)

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RECOMMENDED TRAVEL VACCINATIONS

Treatment :

uncomplicated

:single dose of 750-1000 mg from quinolone for diarrhea

more severe forms: 3-day course for or rifaximin (200mg

tid

for

3 days

).Because of quinolone-resistant Campylobacter in

Thailand and India, use of azithromycin as a backup should be considered.

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Traveler's Diarrhea (TD)