Transcript epidemiology and control of diphtheria and tetanus

EPIDEMIOLOGY
AND
CONTROL OF
DIPHTHERIA
AND
TETANUS
Epidemiology:
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Identification
Infectious agent
Occurrence
Reservoir
Mode of transmission
I.P.
Period of communicability
Susceptibility and resistance
Methods of Control:
A.Preventive measures:
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Vaccination
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Public education
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Others
B.Control of patients, contacts and
environment:
C.Epidemic Measures:
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Prompt reporting
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IG for outbreaks
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Priorities if short of vaccine
DIPHTHERIA
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Epidemiology:
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Identification: an acute bacterial disease of
tonsils, pharynx, largnx, nose, occasionally of
other mucous membranes or skin and
sometimes the conjunctiva or genitalia.
The characteristics lesion, caused by liberation of
a specific cytotoxin secondary to proliferation of
bacteria at a focus of infection.
Patches of an
adherent grayish membrane with surrounding
inflammation.
The focus is usually the throat, spreading to the
fauces, pharynx and larynx.
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Infectious Agent:
Coryndbacterium diphtheria of biotype:
Gravis,
Mitis,
Intermedius
 Reservoir:
Man
 Carriers: Do exist but are less infective than cases.
 Mode of transmission:
Pts. * or carriers (direct droplet).
Soiled articles (indirect).
Raw milk (served as a vehicle).
 Occurrence:
* Geography: World wide.
A disease of colder months
( temperate zones).
Prevalence depends on:
- the extent of immunization
- population density.
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Age:
- Unimmunized children < 15 yrs.,
- often found among adults ( where immunization was
neglected).
- Unusual among infants.
 Sex:
No sex difference.
 I.P.:
Usually 2-5 days.
 Period of Communicability:
- Variable
(until virulent bacilli disappear from discharges and lesions
(usually 2 wks or less and seldom > 4 wks).
** Rarely chronic carriers may shed organisms for 6/12 or >.
 Susceptibility
and Resistance:
- Infants born to immune mothers are
relatively * immune for up to 6/12.
- Recovery from clinical attacks are (in the
majority) followed by lasting immunity.
- Immunity acquired through inapp.infectn.
- In tropics, cutaneous dipth. can pass
unnoticed and induces significant
immunity.
- In U.S.A. > 40% of adults lack protective
levels of circulating antitoxin.
 Clinical
Manifestations
- The S & S depend upon:
Site of infection,
Immunization status,
escape of toxin to ciculation.
- Diphtheria is classified clinically on the
basis of the anatomic location of the initial
infection, and the dipth. Membrane:
1-Nasal Diphtheria: initially resemble mild
common cold with rhinorrhea and paucity
of systemic symptoms.
2- Tonsillar and pharyngeal diphtherias:
(insidious and more severe)
Accompanying symptoms& signs:
anorexia, malaise, low grade fever and
pharyngitis. Within 1-2 days a memb. appears
of various extent (depending on the immune
status of the host).
Cervical lymphadenitis is variable.
“Bull Neck”: edema of soft tissue of neck.
3- Laryngeal diphtheria:- downwards extension
of memb. from pharynx,
Occasionally, only laryn. Involvement is
present (pts. toxicity less prominent).
4- Cutaneous, vulvovaginal, conjunctival and aural
dipheria also occur.
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Complications:1. Respiratory Obstruction leading to death (young
children with laryng. or tracheal diph. due to
occlusion of airway by dipht. memb. + edema of
neck).
2. Myocarditis may follow both severe and mild cases
of dipht. esp. among pts. with extensive local lesions
who experienced delay in administn. of antitoxin (2nd
week).
3. Neurologic Complications:
- Usually appear after a variable latent period,
- predominantly bilateral motor > sensory ,
- usually resolves completely.
Control and Prevention
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Preventive Measures:
1- Active immunizatn. with diph. toxoid, including
an adequate program to maintain immunity.
Triple Antigen DPT.
 Schedules:
a- < 6-7 yrs: 4 doses of DPT Ist 3 doses to be
given at 4-8 wks. Intervals beginning when
infant is 6-8 wks. Old (2 and 4 and 6 months
in S.A.) The 4th dose given 1 yr after the 3rd
dose. A 5th dose, usually given at school
entry.1
b. For persons > 7 yrs., : for previously unimm.
Individual, a primary series of 3 doses of
tetanus and dipth. Toxoids (adult type, Td) is
given. The Ist 2 doses at 4-8 wks. Intervals, the
3rd dose 6/m – 1 yr. After 2nd dose.
c. Active protectn. Should be maintained by
administering a dose of “Td every 10 yrs.”
thereafter, (esp. for persons who are at higher
risk to pt. exposure e.g. health workers).
2 . Educational measures:
to inform the public and esp. parents of young
children of the hazards of diptheria and the imp.
of immunization.
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Control of pt., contacts and immediate
environ.:- Report to local health authority.
- Isolation :
Strict for pharyn. diph.
Contact isolatn. for cutan. diph.
{Until 2, cultures from both throat and nose (or
skin lesions) taken at least 24 hrs. apart, and
not less than 24 hrs. after cessatn. Of
antimicrob. therapy, fail to show dipht. bacilli.}
Or when culture is impractical, isolatn. may be
ended after 14 days of appropriate antibiotic
Rx.
 Concurrent disinfectn.: of all articles in
contact with pts.
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Management of case:1 . DAT and antibiotics to be started
immediately without waiting for lab. results.
2. Rest and observation, to cover the period of
potential cardiac damage and paralysis ,
3. Avoid limbs deformity + ensure joint mobility.
4. Tracheostomy and artificial respiration .
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Management of Contacts:
1. For those who are previously immunised ,
adminst . a booster dose (Td).
2. For those not imm. they should be cultured
and given DAT followed by immun. later on.
Tetanus
 Infectious
Agent:Clostridium tetani
 Identification:
An acute disease induced by an exotoxin
of the tetanus bacillus, which grows
anaerobically at the site of an injury. The
disease is characterised by painful ms.
contractions, primarily of the masseter
and neck ms., secondarily of trunk ms.
 Clinical
Picture: ( common early S & S ) lock jaw and muscular pain,
- Abdominal rigidity,
- Generalised spasms ,
( frequently induced by sensory stimuli)
typical features of the tetanic spasm are the
facial expression known as
“risus sardonicus”.
Note : Dysphagia is an uncommon
but
important early symptom.
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Period of onset:
The time bet. the Ist symptom and the appearance of
reflex ms. spasm.
( A typical tetanus pt. is apprehensive and alert. All
voluntary ms. are hypertonic esp. on face, neck, spine
and abd. wall).
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Complications:
“ Tetanus is not simply a disorder of motor function. The
autonomic N.S. is also rendered unstable by the action
of the toxin.”
- Death occurs mainly due to either asphyxia or
autonomic instability (e.g. sudden changes in pulse
rate, bl.P., and cardiac output).
- Serious cardiac arrythmias, excessive sweating and fever
may occur.
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I.P.:
Usually 5-10 days (36 hrs and several
months have been reported).
 Reservoir:- Intestine of animals, in which the
organism is a harmless normal inhabitant. Soil
contaminated with animal and rarely human
feces.
 Mode of Transmission:
- Tetanus spores introduced into the body,
usually through a puncture wound contaminated
with soil … etc.
- The *umbilical wound when (unhyg.) dressed is
the main portal of entry in “T. neonatorum.”
- The presence of necrotic tissues, foreign
bodies, poor local bl. supply, favours growth of
the anaerobic pathogen.
 Period
of Comm.:- Not directly transmitted from person to
person.
 Susceptibility and Resistance:- Suscept. is general.
- Active immunity is induced by tetanus
toxoid and persists for at least 10 yrs. after
full immunizatn.
 Recovery from tetanus may not result in
immunity. Second attack can occur.
Methods of Control:
Preventive Measures:
1. Active Immunization with tetanus toxoid
every 10 yrs.
- Protections after the initial basic series has
been completed
- single booster doses induce high levels of
immunity.
eg. DPT Usually used for series imm. program.
DT For children < 7 yrs.
Td For adults.
Tetanus toxoid is recommended for universal
use regardless of age, esp. for people at
greater than usual risk of traumatic injury
(workers, policeman and people in contact
with domestic animals).
2. Education on:
- the necessity of complete immunization
with T. Toxoid,
- the kind of injury particularly liable to be
complicated by tetanus, the potential
need after injury for passive and *active
phrophylaxis.
Control of pt., contacts and
immediate environment:
1.
2.
3.
4.
5.
Report to local health authority.
No isolatn.
Immunizatn. Of contacts:
None
Investigatn. of contacts and source of infectn.:
Specific Rx: human tetanus immunoglobulin*
(TIG) i.m. follow a wound. If TIG not available,
give tetanus antitoxin* in a single large i.v.
dose + parentral penicillin in large doses for
10-14 days.
Specific Treatment
b. Wound should be debrided widely.
c. Maintain an adequate airway.
d.Employ sedatn. (as indicated) or ms. relaxant.
e.Active imm. should be initiated concurrently with
therapy.
6.Destruction of environmental spores:
- esp. in operating theaters.
- Special air-flow equipment and filtered ventilation.
- Reduce airborne particles. Surgical instruments
and dressing sterilizatn (use of autoclaves).
Disinfectn. e.g. formaldehyde.