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Home › Topics › Infectious Diseases › Infections A-Z › Rashes in pregnancy - HPA guidelines, information and advice ›The pregnant patient in contact with a non-vesicular rash illness
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The pregnant patient in contact with a non-vesicular rash illness

Contact is defined as being in the same room (eg house or classroom or 2-4 bed hospital bay) for a significant period of time (15 minutes or more) or face-to-face contact.

This definition is based on experience with VZV exposure and errs on the side of caution. This definition of contact is probably sensible for all nosocomial exposures. In community exposures, which are probably more frequent and less likely to be well defined, it may be more practicable to consider a less stringent definition of contact, especially for parvovirus B19 infections where household exposure is overwhelmingly the most important source of infections in pregnancy (followed by intense occupational exposure).

If the rash in the contact is vesicular ( varicella ), see Management of varicella/herpes-zoster exposure in pregnancy.

The aetiology of the rash in the contact may be diverse, and include noninfective causes. The possible causes which warrant consideration include measles, rubella and parvovirus B19. Other possible infective causes in the contact (e.g. enterovirus) should await development of illness in the pregnant woman. Investigation is recommended for rubella and parvovirus B19 in all cases unless there is a strong reason to suspect measles, and susceptibility to rubella is unlikely.

  • If a woman has had one of the following, she should be reassured that the likelihood of rubella is extraordinarily remote, that specific rubella investigation is not required, but to return if a rash develops:
    • At least two previous rubella antibody screening tests which have detected antibody
    • At least two documented doses of rubella vaccine
    • One documented dose of vaccine followed by one previous rubella antibody screening test which has detected antibody.
  • If rubella susceptibility is possible (criteria above not present), a serum should be obtained as soon after contact as possible (full details must be given on the request form as listed in Laboratory investigation to ensure correct interpretation of results).
  • The laboratory should simultaneously test for rubella-specific IgG and IgM, and the advice given in algorithm 2a: Pregnant patient in contact with rash illness, and algorithm 2b: Investigation for rubella of pregnant woman exposed to rash illness, followed. If rubella specific IgG is detected, and rubella-specific IgM is not detected, women should be reported as "No evidence of recent primary rubella". There may be rare occasions when detection of rubella-specific IgG may precede by 1-2 days the development of specific IgM in the evolution of the antibody response in primary rubella: in a pregnant patient with a rash of onset in the previous 10 days, if a low concentration (say
  • Active investigation for reinfection by obtaining and testing later sera is not indicated given the low incidence of rubella in the UK (and hence it being unlikely that the contact had rubella), and the low risk to the fetus of reinfection in the absence of a maternal rash.
  • If rubella-specific IgM reactivity is detected, similar caveats as to the specificity of this result, and procedures to be followed, are as detailed in Laboratory investigation of rubella.

The pregnant woman should be investigated for asymptomatic parvovirus B19 infection ( algorithm 2a: Pregnant patient in contact with rash illness, algorithm 2c: Investigation for parvovirus B19 of pregnant woman exposed to rash illness), and investigation not delayed to ascertain if symptomatic infection occurs. This is because:

  • Maternal asymptomatic parvovirus B19 infection is at least as likely to infect and damage the fetus as symptomatic infection (15).
  •  Active management of the infected fetus may reduce the risk of adverse outcome (33) ( Management of proven infection of parvovirus B19).

Serum should be collected as soon after contact as possible and submitted to the laboratory with full clinical and epidemiological details ( Laboratory investigation).

Serum should be tested for both parvovirus B19-specific IgG and IgM. If specific IgG or IgM are not detected, further serum should be collected and tested one month after last contact. If specific IgM is detected, but specific IgG not detected, a further serum should be collected and tested immediately. If specific IgG is detected (c 50% probability), but specific IgM not detected, the woman will be reassured and a report issued, "Parvovirus B19 infection at some time, but not recently". If, after one month testing, specific IgG and IgM are not detected, the woman will be reassured and a report issued "No evidence of recent parvovirus B19 infection, but is susceptible".

If the source patient is suspected as having measles based on epidemiology and clinical features, consideration should be given to passive prophylaxis with intra-muscular human normal immunoglobulin (HNIG) as soon as possible after exposure, but within six days (34). There is no evidence that post-exposure prophylaxis with HNIG confers any benefit for the fetus, although it may attenuate maternal illness. Clinical features suggestive of measles are described in Risk of different rash illnesses in pregnancy - measles. Additional factors that would increase the likelihood of measles are as follows:

  • The rash contact took place when the woman was abroad
  • The contact had travelled abroad
  • The contact has not received measles vaccine in the past
  • The contact has been hospitalised recently
  • The contact is linked epidemiologically to a confirmed measles case.

If the woman has received two doses of measles vaccine in the past, in view of the low incidence of measles infection in the UK, she should be reassured as to the low probability of her becoming infected. If there is no or poorly documented history of vaccination, serum should be collected and administration of HNIG should await an urgent determination of measles-specific IgG (available through local laboratory). If measles specific IgG isdetectedwithin10daysofcontact(>95% probability of being "immune" in the UK and particularly if born before 1970) further action is unnecessary. Failure to detect measles-specific IgG would warrant administration of HNIG, and serological follow-up three weeks after last contact: HNIG may attenuate but not prevent measles. If contact was more than 10 days prior to presentation, serum should be collected and stored. Management would be expectant and specific measles serological investigation only performed if rash illness develops.

 

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