Measles

 

 Measles is…

* an acute viral infection characterized by a maculopapular rash erupting successively over the neck, face, body, and extremitis and accompanied by a high fever.

                              ETIOLOGY

 Measles virus

*An RNA virus of the genus Morbillivirus in the family of Paramyxoviridae

*One serotype, human’s only host

*Stable  antigenicity

*Rapidly inactivated by heat and light

*Survival in low temperature.

                          EPIDEMIOLOGY

*Infection sources

n  Patients of acute stage and viral carriers of  atypical measles

*Transmission

n  Highly contagious, approximately 90% of susceptible contacts acquire the disease.

n  Respiratory secretions: maximal dissemination of virus occurs by droplet spray during the prodromal period (catarrhal stage).

n  Contagious from 5 days before symptoms, 5 days after onset of rash

n  Seasons: in the spring, peak in Feb-May

 

PATHOGENESIS AND PATHOLOGY

*Portal of entry

n  Respiratory tract and regional lymph nodes

n  Enters bloodstream (primary viraemia) è monocyte – phagocyte  system è target organs (secondary viraemia)

*Target organs

n  The skin; the mucous membranes of the nasopharynx,

          bronchi, and intestinal tract; and in the conjunctivae, ect

Resulting In-----

 

1) Koplik spots and skin rash: serous exudation and proliferation of endothelial cells around the capillaries

2) Conjunctivis

 

    

         

PATHOGENESIS AND PATHOLOGY

3) Laryngitis, croup, bronchitis :general inflammatory reaction

4) Hyperplasia of lymphoid tissue: multinucleated giant cells (Warthin-Finkeldey  giant cells) may be found

5) Interstitial pneumonitis: Hecht giant cell pneumonia.

6) Bronchopneumonia: due to secondary bacterial infections

7) Encephalomyelitis: perivascular demyelinization occurs in areas of the brain and spinal cord.

8) Subacute sclerosing panencephalitis(SSPE):

    degeneration of the cortex and white matter with intranuclear and intracytoplasmic inclusion bodies

 

CLINICAL MANIFESTATION

 

Typical Manifestation:

 

    patients havn’t had measles immunization, or vaccine failure with normal immunity or those havn’t used immune globulin

 

1. Incubation period (infection to symptoms) :

         6-18days (average 10 days)

 

2. Prodromal period:

n    3-4 days

n    Non-specific symptoms: fever, malaise, anorexia, headache

n    Classical triad: cough, coryza, conjunctivitis (with

      photophobia, lacrimation)

CLINICAL MANIFESTATION

        Enanthem (Koplik spots):

 

n  Pathognomonic for measles

n  24-48 hr before rash  appears

n   1mm, grayish white dots with

     slight, reddish areolae

n   Buccal mucosa, opposite the

     lower 2^nd molars

n   increase  within 1day and spread

n   fade  soon after rash onset

CLINICAL MANIFESTATION

CLINICAL MANIFESTATION

     3. Rash period

          3-4days

         Exanthem:

           Erythematous, non-pruritic, maculopapular

n       Upper lateral of the neck, behind ears, hairline,

         face è trunk  arms and legs feet

 

n       The severity of the disease is directly related to

         the extent and confluence of the rash

,

CLINICAL MANIFESTATION

CLINICAL MANIFESTATION

CLINICAL MANIFESTATION

CLINICAL MANIFESTATION

   Temperature:

n     Rises abruptly as the rash appears

n     Reaches 40℃ or higher

n     Settles after 4-5 days – if persists, suspect secondary

       infection

    Coryza, fever, and cough:

n     Increasingly severe up to the time the rash has covered the

       body

    Lymphadenopathy (posterior cervical region, mesenteric) splenomegaly, diarrhoea, vomiting

          Chest X ray:

n    May be abnormal, even in uncomplicated cases

 

CLINICAL MANIFESTATION

 4. Recovery period

     3-4days

     Exanthem:

n      Fades in order of appearance

n      Branny desquamation and brownish discoloration

 

     Entire illness – 10 days

 

CLINICAL MANIFESTATION

CLINICAL MANIFESTATION

Atypical  Manifestation:

 

1.  Mild measles

n      In patients: administered immune globulin products during the incubation period and immunized against measles; in infants <8mo

n      Long incubation period  and short prodromal phase

n      Mild symptom

n      No Koplik spot

n      The rash tends to be faint, less macular, pinpoint

n      No branny desquamation and brownish discoloration  occur as the rash fades

n      No complications and short course

CLINICAL MANIFESTATION

2. Severe measles:

n    In cases with  malnutrition, hypoimmunity and secondary

      infection

n    Persistent  hyperpyrexia, sometimes with convulsions and even

      coma

     Exanthem:

n     Completely covered the skin

n     Confluent, petechiae, ecchymoses

n     The hemorrhagic type of measles (black measles), bleeding

       may occur from the mouth, nose, or bowel. disseminated

       intravascular coagulation (DIC) 

CLINICAL MANIFESTATION

CLINICAL MANIFESTATION

3. Atypical measles syndroma:

n     Recipients of killed measles virus vaccine, who later come in

        contact with wild-type measles virus.

n     Distinguished by high fever, severe headache, severe abdominal

        pain, often with vomiting, myalgias, respiratory symptoms,

        pneumonia with pleural effusion

      Exanthem:

n     First appears on the palms, wrists, soles, and ankles, and

        progresses in a centripetal direction.

n     Maculopapular è vesicular è purpuric or hemorrhagic.

n     Koplik spots rarely appear

 

CLINICAL MANIFESTATION

CLINICAL MANIFESTATION

4. Measles absent of rush

n     Immunodepressed, or passive immunized recently cases and

       occasionally in infants <9mo who have appreciable levels

       of maternal antibody

n     Non-specificity

n     Difficult to diagnosis

 

COMPLICATIONS

1. Respiratory Tract

*  Laryngitis, tracheitis, bronchitis – due to measles itself

*  Laryngotrachobronchitis (croup) –cause airway obstruction to require tracheostomy

*  Secondary pneumonia – immunocompromised, malnourished patients. pneumococcus, group A

      Streptococcus, Staphylococcus aureus  and

      Haemophilus influenzae type B.

*  Exacerbation of TB

COMPLICATIONS

   2. Myocarditis

 

   3. Malnutrition and Vitamin A deficiency

COMPLICATIONS

    4. CNS

*The incidence of encephalomyelitis is 1-2/l,000 cases of measles

*Onset occurs 2-5 days after the appearance of the rash

*No correlation between the severity of the rash illness and

      that of the neurologic involvement

n    Earlier - direct viral effect in CNS

n    Later – immune response causing demyelination

n    Significant morbidity, permanent sequelae – mental

      retardation and paralysis

*Subacute sclerosing panencephalitis (SSPE): extremely rare, 6-10 years after infection. Progressive dementia, fatal. Interaction of host with defective form of virus

 

LABORATORY EXAMINATION

*Isolation of measles virus from a clinical specimen (e.g., nasopharynx, urine)

*Significant rise in measles IgG by any standard serologic assay

*Positive serologic test for measles IgM antibody

*Immunofluorescence detects Measles antigens

*Multinucleated giant cells in smears of nasal mucosa

 

*Low white blood cell count and a relative lymphocytosis in PB

*Measles encephalitis – raised protein, lymphocytes in CSF

 

DIAGNOSIS

characteristic clinical picture:

    Measles contact

    Koplik spot

    Features of the skin rash

    The relation between the eruption and fever

 

    Laboratory confirmation is rarely needed

 

DIFFERENTIAL DIAGNOSIS

*The rash of measles must be differentiated from that of

*rubella;

*roseola intantum;

*enteroviral  infections;

*scarlet fever;

*and drug rashes.

 

 

 

DIFFERENTIAL DIAGNOSIS

DIFFERENTIAL DIAGNOSIS

TREATMENT

*Supportive, symptom-directed

         Antipyretics for fever

         Bed rest

         Adequate fluid intake

         Be protected from exposure to strong light

*Antibiotics for otitis media, pneumonia

*High doses Vitamin A in severe/ potentially severe measles/ patients less than 2 years

        100,000IU—200,000IU

 

PREVENTION

*1. Quarantine period

      5 days after rash appears, longer for complicated measles

*2. Vaccine

      The initial measles immunization is recommended at 8mo of

         age

         A second immunization is recommended routinely at 7yr of

         age 

*3. Postexposure Prophylaxis

       Passive immunization with immune globulin (0.25mL/kg)

       is effective for prevention and attenuation of measles within

         5 days of exposure.