diease

German measles


German measles overview and Definition

Rubella is a communicating disease which is caused by the virus.  Rubella can cause miscarriages or serious birth defects in a developing baby if a woman is infected while she is pregnant. The best protection against rubella is MMR (measles-mumps-rubella) vaccine.


Structure of German measles

The rubella virus belongs to the Togaviridae family. The details of the togaviridae family are given below

Togaviridae

  1. Morphology
    • Viruses of Togaviridae family are Spherical, Enveloped virus with icosahedral
    • Size: 60 – 70 nm in diameter.
    • Genetic Material :- (+) ssRNA.
  2. Classification
    • Togaviridae contains two Genera: Alphavirus & Rubivirus.
    • Viruses of Togaviridae are transmitted principally by Mosquitoes.
    • Genus Rubivirus contains Rubella virus, is not Arthropod borne.
    • The genus Alphaviruses includes:-
      1. Encephalitis Group
        1. Western equine encephalitis (WEE)
        2. Eastern equine encephalitis (EEE)
        3. Venezuelan equine encephalitis (VEE)
      2. Febrile Illness Group
        1. Chikungunya virus
        2. O’nyong-nyong virus
        3. Sindbis Virus
        4. Ross river virus

 


Pathophysiology

Respiratory transmission of virus resulting in lymphadenopathy and replication takes place in nasopharynx. The viremia takes place by 5-7  days after the infection. Then viruses shed from the nasopharynx. The primary viraemia is concerned only to the reticuloendothelial system. The secondary viraemia is concerned to the body surfaces. Epithelial  necrosis, virus shedding and giant cell formation occurs revealing the symptoms externally. With the onset of the rash the symptoms begins.


Routes of Transmission

The main route of transmission is by contacting through fomites of the infected persons. Also it might spread from droplets of the infected persons. Vertical transmission is also possible that is the transmission from the mother to the child and it is termed as congenital rubella.


Clinical signs & symptoms

  • pink or red rash that begins on the face and then spreads downward to the rest of the body
  • mild fever, usually under 102°F
  • swollen and tender lymph nodes
  • runny or stiffy nose
  • headache
  • muscle pain
  • inflamed or red eyes
  • prolonged headache
  • stiff neck
  • earache

In some cases the german measles may lead to damage to brain cells and spinal cord.

The congenital rubella can cause:

  • delayed growth
  • intellectual disabilities
  • heart defects
  • deafness
  • poorly functioning organs

 


Differential Diagnosis

Immunosorbent assay- detect the virus specific IgM or IgG antibodies.

Greater than fourfold rise in titer between acute and convalescent sera and cerebo spinal

fluid containing virus specific IgG or IgM or both are the diagnostic features.

Real-time polymerase chain reaction (RT-PCR)- is valuable in the early confirmation of

arbovirus infections, particularly chikungunya. However, the value of RT-PCR is limited to

diagnosis in the viraemic phase, with later infection requiring serology.

Direct immunofluorescence assay -to detect chikungunya IgM has a high sensitivity and

specificity and is used in the latter. stages.However, the use of these tests in the tropics may be limited to the financial strains.

A complement fixation test: Which provides antigen to antibody reactions.

Viral culture:  A blood or fluid is withdrawn and the investigations are made.

Laboratory criteria for measles diagnosis are:

  • a positive serologic test for measles IgM antibody, or
  • a significant rise in measles antibody level by any standard serologic assay, or
  • isolation of measles virus from a clinical specimen.

A laboratory-confirmed case need not meet the clinical case definition. Serologic confirmation should be attempted for every suspected case of measles and is particularly important for any case that cannot be epidemiologically linked through a chain of transmission to a confirmed case. However, reporting of suspected or probable cases, investigation of cases, and the implementation of control activities should not be delayed pending laboratory results.

Blood for serologic testing should be collected during the first clinical encounter with a person who has suspected or probable measles. The serum should be tested for measles IgM antibody as soon as possible using an assay that is both sensitive and specific (e.g., direct-capture IgM EIA method). Correct interpretation of serologic data depends on the timing of specimen collection in relation to rash onset and on the characteristics of the antibody assay used. This timing is especially important for interpreting negative results because IgM antibody may not be detectable with some less sensitive assays until at least 72 hours after rash onset. Measles IgM may be detectable at the time of rash onset, peaks approximately 10 days after rash onset, and is usually undetectable 30-60 days after rash onset. In general, if measles IgM is not detected in a serum specimen obtained in the first 72 hours after rash onset from a person whose illness meets the clinical case definition for measles, another specimen should be obtained at least 72 hours after rash onset and tested for measles IgM antibody. Measles IgM is detectable for at least 1 month after rash onset.


Prognosis

The symptoms might subside within 2-3 weeks .

 


Prevention

The best way to prevent the rubella is through the vaccination process.

Avoid contaminating with the fomites from the infected persons.

Take lots of water and fluid

Maintain healthy lifestyle.