Exanthemic infectious diseases are a popular topic in exams, especially in pediatrics. Get a brief overview of the most important diseases, including important distinctive characteristics.
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The young boy pictured here, displayed the characteristic maculopapular rash indicative of rubella, otherwise known as German measles, or 3-day measles.


Measles (Rubeola)

This thin-section transmission electron micrograph (TEM) revealed the ultrastructural appearance of a single virus particle or “virion” of the measles virus. The measles virus is a paramyxovirus of the genus Morbillivirus. It is 100-200 nm in diameter, with a core of single-stranded RNA, and is closely related to the rinderpest and canine distemper viruses.

Measles is a typical disease in childhood. The causative organism is the measles virus (morbillivirus) — an RNA-virus which can be passed on by droplets or airborne (flying infection) over a long distance. The high contagiousness and infectivity are characteristic. Persons who are not vaccinated and infect themselves regularly contract from the measles.

Firstly, the virus infects the lymphatic tissue of the upper respiratory tract (prodromal stage) before a viraemic showing with an occurrence of the measles exanthema (exanthema stage) takes place.

Pathology of the Measles

Measles. This child shows a classic day-4 rash with measles.

After an incubation period of around about 2 weeks, typical prodrome in the form of high temperature, pharyngitis (a sore throat), rhinitis, bronchitis, conjunctivitis and photophobia occur. At this point, patients are already infectious. By the end of the prodromal stage, which lasts for 2—3 days, the measles-characteristic Koplik’s spots at the buccal mucosa, located in the amount of the lower molars, occur.

The temperature decreases again initially and reaches another peak with the occurrence of the measles exanthema (twin-peaked increase in a fever). The extensive brownish impressive exanthema characteristically starts behind the ears and spreads from this point over the whole body. The exanthema stage takes 7—10 days.

Note: Children infected with measles are seriously ill (high temperature). Pathognomic is a biphasic course of disease with a twin-peaked increase in fever.

Complications of the Measles

The measles virus is a lymphotropic virus which causes a weakening of the immune system. This can especially trigger grave consequences in the case of immune-compromised patients: besides bacterial superinfections (Otitis media, pneumonia and laryngotracheitis) the virus itself can cause serious after-effects.  This includes measles pneumonia and the measles encephalitis. The latter stands for one of the most fearsome complications and can be divided into three forms according to its occurrence and course of disease:

  • Postinfectious measles encephalitis occurs about 1 week after the start of the exanthema and accompanies neurological symptoms (disturbed consciousness and seizures amongst others). The lethality of the disease is very high at a rate of about 25 %.
  • Subacute sclerosing panencephalitis (SSPE): The SSPE is a late complication of the measles which rarely proceeds lethally and occurs typically after 6 – 8 years of an undergone measles infection.
  • Measles inclusion body encephalitis (MIBE): The MIBE is a measles complication which only occurs in the case of immunocompromised patients and is afflicted with a high lethality (30%).
Note: Typical measles complications are evoked by bacterial superinfections. The measles virus can especially cause, in the case of immune-deficient patients, grave lethal courses.

Diagnostics of the Measles

The diagnostics are made with the aid of the clinic and the virus-specific IgM antibodies in the serum.

Therapy and prevention of the Measles

As no causal therapy is available, the prevention in the early childhood is crucial. The Standing Vaccination Committee at the Robert-Koch-Institute, therefore, recommends a basic immunization against measles (live vaccine) from the completed 11th month of life, which should be followed by a second vaccine during the second year of the child’s life (15th – 23rd month).

In the meantime, mumps and rubella, as well as varicella, should be vaccinated against. For this purpose, combination vaccines are available for which the STIKO pronounced the following recommendation:

  • Vaccination date (11 – 14th month): threefold combination vaccine against mumps, measles, and rubella (MMR) + varicella vaccination on another body part (contralateral arm). If both vaccinations are not executed after the first vaccination date, a minimal period of four weeks until the next vaccination should be maintained.
  • Vaccination date (15th – 23rd month): fourfold combination vaccine (MMR-V) possible.
Note: Live vaccines should either be executed simultaneously or consecutively, provided that a minimal period of four weeks is maintained!

Post-exposition prevention: After the exposition of unvaccinated persons, an immunization within the first 3 days after the initial contact is appropriate. In the case of a person at risk (pregnant women, immunocompromised patients, infants < 6 months), a passive immunization with human immunoglobulin within a period of 2 – 6 days can be considered following the post-exposure.

Image: “Rates of measles vaccination worldwide” by BlankMap-World8.svg: AMK1211 derivative work: Master Uegly (talk). Licence: CC BY-SA 3.0

Rubella (German Measles)

Rubella is a viral disease in childhood which is communicated via droplet infection. The disease is especially dangerous for pregnant women as a diaplacental transmission on the unborn child with following grave organ complications (rubella embryopathy) which may take place.

Pathology of Rubella

Rash of rubella on the skin of a child’s back. Distribution is similar to that of measles, but the lesions are less intensely red.

The first symptoms occur after an incubation period of 2 – 3 weeks. As the virus initially spreads in the lymph nodes, at first painful lymphomas impress in the area of the cervical, retro-auricular and occipital lymph nodes.

A headache and a general feeling of malaise can occur collaterally but are not obligatory. 5 – 7 days after the first symptoms (lymph node disease), a rubella exanthema appears which starts like the measles behind the ears and spreads from this point over the whole integument.

Note: The painfully swollen lymph nodes at the outset of the infection are typical for a rubella infection!

Complications of Rubella

Complications arise especially for the unborn child as far as the mother contracts from rubella for the first time during the pregnancy. The danger of malformations is especially high in early pregnancy (the first two months of the pregnancy). Typical organ damages are summarized as Gregg-Trias according to the first person to describe them: labyrinthine deafness, cataract, heart defect (septal defects among others).

In the case of a person who fell ill in the postnatal stage, self-limiting arthritides can occur. Complications of the nervous system (encephalitis, encephalomyelitis) and/or the hematopoietic system (thrombocytopenic purpura) are very rare.

Diagnostics of Rubella

Transmission electron micrograph of the rubella virus.

The diagnosis of the rubella infection happens serologically according to the detection of rubella IgM in blood samples which are taken at two different points in time where the increase in titer is proving. Used methods are the haemagglutination-inhibition test (method of choice) or the ELISA.

In the case of pregnant women, a direct pathogen detection in the maternal blood, as well as in the amniotic fluid (amniocentesis), or rather in the fetal blood (cordocentesis), should be striven for.

Therapy and prevention of Rubella

There is no therapy for a rubella infection. The Standing Vaccination Committee at the Robert-Koch-Institute, therefore, recommends the vaccination of all infants at the vaccination proficient age. The general immunization takes place as an injection of the attenuated live vaccine which is done twice from the completed 11th month of life at the same time as the measles and mumps vaccination (see measles).

The young boy pictured here, displayed the characteristic maculopapular rash indicative of rubella, otherwise known as German measles, or 3-day measles.

If the vaccination is not successful in infancy, it is meant to be fetched later in the case of girls and child-bearing women. If the second vaccination dose was not administered, it is meant to be fetched later preferably until the age of 18 according to the recommendation of the STIKO. For child-bearing women, a catch-up is generally possible at a later point in time as well.

In the course of pregnancy, the examination of the rubella titer is part of the initial examination. Demonstrable immunity exists at a rubella IgM titer > 1:32 in the haemagglutination-inhibition test (HAH), but is also assumed at a titer of 1:16.

Chickenpox (Varicella)

Causative organisms of chickenpox are the varicella zoster virus (VZV), a DNA virus which is part of the group of the human herpes viruses (HHV3). The communication happens via contact with the infectious (virus containing) content of blisters or airborne. Like the measles virus, the varicella zoster virus has a high contagiousness as well.

Pathology of Chickenpox (Varicella)

The varicella typical skin eruptions, which show a stage-like development of reddish papules up to blisters filled with pathogens and pustules, occur after an incubation period of about 14 days. The blisters finally scab and heal by crust formation. As new efflorescences recurrently occur, there is a “colorful picture” of efflorescences of different ages (so-called Heubnersche-Sternenkarte).

The exanthema is accompanied by a prominent itching and affects the skin as well as the hairy scalp. Additionally, there is an enanthem of the mucosas. High temperature can occur as an attendant symptom; however, there usually is no dominant feeling of malaise.

Complications of Chickenpox (Varicella)

In general, there is a danger of bacterial superinfections which affect primarily the skin and result from the scratching of the blisters. Beyond that, bacterial inflammations of the middle ear (Otitis media) and pneumonia can occur.

Viral complications are rare. Pneumonia is as depicted as meningitides and encephalitides.

The chickenpox disease is marked with complications in the pregnancy as the virus can be communicated diaplacentarly onto the fetus. If the mother falls ill within the first and second trimester, a grave infection of the fetus with malformations of the limbs (extremity hypoplasia), as well as damages of the skin and the organs, can occur (varicella syndrome). Furthermore, newborns can fall severely ill if the mother falls ill five days before until two days after the birth (neonatal varicella).

Shingles of Chickenpox (Varicella)

Herpes zoster neck

Image: “Herpes Zoster Neck” by Gentgeen. Licence: CC BY-SA 3.0

The varicella zoster virus persists after a previous infection within the spinal ganglions and can be reactivated by transient (for example stress) or a continuous immune impairment. The clinical appearance complies with the one of chickenpox, but is restricted to the dermatome of the affected skin nerves. Neuralgiform pain is typical which precedes the efflorescences and can continue after the subsidence of the exanthema (postzosterneuralgy). Occasionally, high temperature and a general feeling of malaise arise.

Diagnostics of Chickenpox (Varicella)

Chickenpox is a visual finding. A pursuing diagnosis is regularly not necessary. The intrauterine varicella infection in early pregnancy constitutes an exception (until the 21st week of pregnancy) for which a detection of pathogens (PCR) in the amniotic fluid (amniocentesis) should be strived for.

Therapy of Chickenpox (Varicella)

Zinc mixtures, which can be combined with systemically effective antihistamines, are applied to the skin in order to reduce the itching. An administering of acyclovir is indicated in the case of a neonatal varicella infection.

A birth should generally not take place in the exanthema stage of the mother. Per the exposition of pathogens, an early delivery should be strived for.

In the case of shingles, an administering of aciclovir, in relation to the gravity of the complaints, can be considered. A pain management therapy, according to the WHO level scheme, is to be introduced for the treatment of the neuralgia.

Prevention of Chickenpox (Varicella)

The varicella vaccination takes place analogous to the measles and rubella vaccination (see above) by an attenuated live vaccine. The STIKO recommends for the first vaccination to carry out the varicella vaccination separately to the triple vaccination (MMR). For the second vaccination, the available fourfold combination vaccine (MMR-V) can be used. The general immunization should be fetched up if the vaccination did not take place in infancy.

For un-vaccinated persons, a vaccination can take place post-expositional after the contact to infected persons.

A passive immunization with varicella zoster immunoglobulin (VZIG) should take place within a period of 96 hours after the contact to an infected person in the case of risk patients. These include:

  • Un-vaccinated pregnant women without varicella in the anamnesis.
  • Immunodeficient persons.
  • Newborn babies without symptoms, as long as the mother falls ill within the critical period around the birth (five days before until two days after the birth).
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