EPIDEMIOLOGY AND CONTROL OF DIPHTHERIA

DIPHTHERIA Epidemiology: 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.

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.

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. 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.

Thick Membrane

Pseudo membrane

‘Bull Neck’

Skin Lesions

Diphtheria Antitoxin (DAT) Produced in horses First used in the U.S. in 1891 Used only for treatment of diphtheria Neutralizes only unbound toxin

Diphtheria – in USA, 1940-2005* Year *2005 provisional total

Diphtheria Antitoxin (DAT) Produced in horses First used in the U.S. in 1891 Used only for treatment of diphtheria Neutralizes only unbound toxin

Diphtheria – in USA, 1940-2005* Year *2005 provisional total

Control and Prevention 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 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.

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.

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 . 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.