Congenital Viral Infections



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Congenital Viral Infections

  • An Overview


Congenital, Perinatal, and Neonatal Viral Infections

  • Intrauterine Viral Infections

  • Rubella

  • Cytomegalovirus (CMV)

  • Parvovirus B19

  • Varicella-Zoster (VZV)

  • Enteroviruses

  • HIV

  • HTLV-1

  • Hepatitis C

  • Hepatitis B

  • Lassa Fever

  • Japanese Encephalitis



Rubella

  • History

  • 1881 Rubella accepted as a distinct disease

  • 1941 Associated with congenital disease (Gregg)

  • 1961 Rubella virus first isolated

  • 1967 Serological tests available

  • 1969 Rubella vaccines available



Characteristics of Rubella

  • RNA enveloped virus, member of the togavirus family

  • Spread by respiratory droplets.

  • In the prevaccination era, 80% of women were already infected by childbearing age.



Clinical Features

  • maculopapular rash

  • lymphadenopathy

  • fever

  • arthropathy (up to 60% of cases)



Rash of Rubella



Risks of rubella infection during pregnancy

  • Preconception minimal risk

  • 0-12 weeks 100% risk of fetus being congenitally infected

  •   resulting in major congenital  abnormalities.

  • Spontaneous abortion occurs in 20% of cases.

  • 13-16 weeks deafness and retinopathy 15%

  • after 16 weeks normal  development, slight risk of  deafness and retinopathy



Congenital Rubella Syndrome

  • Classical triad consists of cataracts, heart defects, and  sensorineural deafness. Many other abnormalities had  been  described and  these are divided into transient, permanent and  developmental.

  • Transient low birth weight, hepatosplenomegaly, thrombocytopenic purpura bone lesions, meningoencephalitis, hepatitis, haemolytic anemia pneumonitis, lymphadenopathy

  • Permanent Sensorineural deafness, Heart Defects (peripheral pulmonary stenosis,

  • pulmonary valvular stenosis, patent ductus arteriosus,   ventricular    septal   defect) Eye Defects (retinopathy, cataract, microopthalmia, glaucoma, severe myopia) Other Defects (microcephaly, diabetes mellitis, thyroid disorders, dermatoglyptic abnormalities

  • Developmental Sensorineural deafness, Mental retardation, Diabetes Mellitus, thyroid disorder



Outcome

  • 1/3 rd will lead normal independent lives

  • 1/3 rd will live with parents

  • 1/3rd will be institutionalised

  • The only effective way to prevent CRS is to terminate the pregnancy



Prevention (1)

  • Antenatal screening

  • All pregnant women attending antenatal clinics are tested  for immune  status  against rubella.

  • Non-immune  women  are  offered rubella vaccination in the immediate post partum period.



Prevention (2)

  • Since 1968, a highly effective live attenuated vaccine has been available with 95% efficacy

  • Universal vaccination is now offered to all infants as part of the MMR regimen in the USA, UK and a number of other countries.

  • Some countries such as the Czech Republic continue to selectively vaccinate schoolgirls before they reach childbearing age.

  • Both universal and selective vaccination policies will work provided that the coverage is high enough.



Laboratory Diagnosis

  • Diagnosis of acute infection

  • Rising titres of antibody (mainly IgG) - HAI, EIA

  • Presence of rubella-specific IgM - EIA

  • Immune Status Screen

  • HAI is too insensitive for immune status screening

  • SRH, EIA and latex agglutination are routinely used

  • 15 IU/ml is regarded as the cut-off for immunity



Typical Serological Events following acute rubella infection

  • Note that in reinfection, IgM is usually absent or only present transiently at a low level



Cytomegalovirus

  • member of the herpesvirus

  • primary infection usually asymptomatic. Virus then becomes latent and is reactivated from time to time.

  • transmitted by infected saliva, breast milk, sexually and through infected blood

  • 60% of the population eventually become infected. In some developing countries, the figure is up to 95%.



Congenital Infection

  • Defined as the isolation of CMV from the saliva or urine within 3 weeks of birth.

  • Commonest congenital viral infection, affects 0.3 - 1% of all live births. The second most common cause of mental handicap after Down's syndrome and is responsible for more cases of congenital damage than rubella.

  • Transmission to the fetus may occur following primary or recurrent CMV infection. 40% chance of transmission to the fetus following a primary infection.

  • May be transmitted to the fetus during all stages of pregnancy.

  • No evidence of teratogenecity, damage to the fetus results from destruction of target cells once they are formed.



Cytomegalic Inclusion Disease

  • CNS abnormalities - microcephaly, mental retardation, spasticity, epilepsy, periventricular calcification.

  • Eye - choroidoretinitis and optic atrophy

  • Ear - sensorineural deafness

  • Liver - hepatosplenomegaly and jaundice which is due to hepatitis.

  • Lung - pneumonitis

  • Heart - myocarditis

  • Thrombocytopenic purpura, Haemolytic anaemia

  • Late sequelae in individuals asymptomatic at birth - hearing defects and reduced intelligence.



Incidence of Cytomegalic Disease



Diagnosis

  • Isolation of CMV from the urine or saliva of the neonate.

  • Presence of CMV IgM from the blood of the neonate.

  • Detection of Cytomegalic Inclusion Bodies from affected tissue (rarely used)



Management

  • Primary Infection - consider termination of pregnancy.

  • 40% chance of the fetus being infected.

  • 10% chance that congenitally infected baby will be symptomatic at birth or develop sequelae later in life.

  • Therefore in case of primary infection, there is a 4% chance (1 in 25) of giving birth to an infant with CMV problems.

  • Recurrent Infection - termination not recommended as risk of transmission to the fetus is much lower.

  • Antenatal Screening – impractical.

  • Vaccination - may become available in the near future.



Neonatal Herpes Simplex (1)

  • Incidence of neonatal HSV infection varies inexplicably from country to country e.g. from 1 in 4000 live births in the U.S. to 1 in 10000 live births in the UK.

  • The baby is usually infected perinatally during passage through the birth canal.

  • Premature rupturing of the membranes is a well recognized risk factor.

  • The risk of perinatal transmission is greatest when there is a florid primary infection in the mother.

  • There is an appreciably smaller risk from recurrent lesions in the mother, probably because of the lower viral load and the presence of specific antibody.

  • The baby may also be infected from other sources such as oral lesions from the mother or a herpetic whitlow in a nurse.



Neonatal Herpes Simplex (2)

  • The spectrum of neonatal HSV infection varies from a mild disease localized to the skin to a fatal disseminated infection.

  • Infection is particularly dangerous in premature infants.

  • Where dissemination occurs, the organs most commonly involved are the liver, adrenals and the brain.

  • Where the brain is involved, the prognosis is particularly severe. The encephalitis is global and of such severity that the brain may be liquefied.

  • A large proportion of survivors of neonatal HSV infection have residual disabilities.

  • Acyclovir should be promptly given in all suspected cases of neonatal HSV infection.

  • The only means of prevention is to offer caesarean section to mothers with florid genital HSV lesions.



Parvovirus

  • Causative agent of Fifth disease (erythema infectiosum), clinically difficult to distinguish from rubella.

  • Also causes aplastic crisis in individuals with haemolytic anaemias as erythrocyte progenitors are targeted.

  • Spread by the respiratory route, 60-70% of the population is eventually infected.

  • 50% of women of childbearing age are susceptible to infection.



Congenital Parvovirus Infection

  • Known to cause fetal loss through hydrops fetalis; severe anaemia, congestive heart failure, generalized oedema and fetal death

  • No evidence of teratogenecity.

  • Risk of fetal death highest when infection occurs during the second trimester of pregnancy (12%).

  • Minimal risk to the fetus if infection occurred during the first or third trimesters of pregnancy.

  • Maternal infection during pregnancy does not warrant termination of pregnancy.

  • Cases of diagnosed hydrops fetalis had been successfully treated in utero by intrauterine transfusions and administration of digoxin to the fetus.



Varicella-Zoster Virus

  • 90% of pregnant women already immune, therefore primary infection is rare during pregnancy

  • Primary infection during pregnancy carries a greater risk of severe disease, in particular pneumonia

  • First 20 weeks of Pregnancy

  • up to 3% chance of transmission to the fetus,

  • recognised congenital varicella syndrome;

  • Scarring of skin

  • Hypoplasia of limbs

  • CNS and eye defects

  • Death in infancy normal



Neonatal Varicella

  • VZV can cross the placenta in the late stages of pregnancy to infect the fetus congenitally.

  • Neonatal varicella may vary from a mild disease to a fatal disseminated infection.

  • If rash in mother occurs more than 1 week before delivery, then sufficient immunity would have been transferred to the fetus.

  • Zoster immunoglobulin should be given to susceptible pregnant women who had contact with suspected cases of varicella.

  • Zoster immunoglobulin should also be given to infants whose mothers develop varicella during the last 7 days of pregnancy or the first 14 days after delivery.




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