PERINATAL INFECTIONS
RubellaInfective organism Rubella virus is a togavirus spread by droplet transmission.
Certain ethnic groups also appear to have higher susceptibility, such as Asian and black women (5 per cent) and Oriental women (8 per cent), compared with less than 2 per cent in white women, with an overall susceptibility of about 2.5 per cent reported for pregnant women in the UK.
Screening
In the UK recommendations are that all women should be offered rubella susceptibility screening early in their pregnancy to identify women at risk of contracting rubella infection and to enable vaccination in the post-natal period for the protection of future pregnancies. For pregnant women who are screened and rubella antibody is not detected, rubella vaccination after pregnancy should be advised. Vaccination during pregnancy is contraindicated because of a theoretical risk that the vaccine itself could be teratogenic, as it is a live vaccine.
Clinical features Rubella
infection is characterized by a febrile rash but may be asymptomatic in the mother in 20–50 per cent of cases. Features of congenital rubella syndrome can include sensorineural deafness, congenital cataracts, blindness, encephalitis and endocrine problems. The risk of congenital rubella infection reduces with gestation. If infection of the fetus does occur the defects caused are also less severe with more advanced gestations. Congenital infection in the fi rst 12 weeks of pregnancy among mothers with symptoms is over 80 per cent and reduces to 25 per cent at the end of the second trimester.Rubella infection prior to the estimated date of conception or after 20 weeks gestation carries no documented risk to the fetus.
Management
If infection during pregnancy is confirmed, the risk of congenital rubella syndrome should be assessed depending on the gestation when infection occurred. If infection occurred prior to 16 weeks gestation, termination of pregnancy should be offered. If the infection occurs later in pregnancy the woman should be given appropriate information and reassured.
Syphilis
Infective organism Syphilis is a sexually acquired infection caused by Treponema pallidum.
Prevalence The prevalence of syphilis in pregnant women has been estimated at approximately 68 per million with regional variation, highest in north-east London. This equates to approximately 50–60 cases per year in the UK.
Clinical features
Primary syphilis may present as a painless genital ulcer 3–6 weeks after the infection is acquired (condylomata lata) however, this may be on the cervix and go unnoticed.
Secondary manifestations occur 6 weeks to six months after infection and present as a maculopapular rash or lesions affecting the mucous membranes.
Ultimately, 20 per cent of untreated patients will develop symptomatic cardiovascular tertiary syphilis and 5–10 per cent will develop symptomatic neurosyphilis.
Mother-to-child transmission of syphilis in pregnancy is associated with fetal growth restriction (FGR), fetal hydrops, congenital syphilis (which may cause long-term disability), stillbirth, preterm birth and neonatal death. The risk of congenital transmission declines with increasing duration of maternal syphilis prior to pregnancy. Adequate treatment with benzathine penicillin markedly improves the outcome for the fetus.
Screening
These can be detected by serological tests. Non-treponemal tests detect non-specifi c treponemal antibodies and include the Venereal Diseases Research Laboratory (VDRL) and rapid plasma reagin (RPR) tests. Treponemal tests detect specifi c treponemal antibodies and include enzyme immunoassays (EIA), T. pallidum haemagglutination assay (TPHA) and the fluorescent treponemal antibody-absorbed test (FTA-abs).
Management
The initial step is to confirm the diagnosis and to test for any other sexually transmitted diseases.
Once a diagnosis of syphilis is confi rmed the genitourinary medicine clinic will institute appropriate contact tracing of sexual partners. Parenteral penicillin has a 98 per cent success rate for preventing congenital syphilis. If a woman is not treated during pregnancy her baby should be treated after delivery.
Toxoplasmosis
Infective organism Toxoplasma gondii is a protozoan parasite found in cat faeces, soil or uncooked meat. Infection occurs by ingestion of the parasite from undercooked meat or from unwashed hands.
Prevalence
The prevalence varies in different countries. It is 16 per 1000 in France but in the UK it is estimated to be less than two per 1000 pregnancies.
Clinical features
The initial infection may be relatively asymptomatic, or may be a glandular fever-like illness. congenital infection is only a significant risk if the mother acquires the infection during or immediately before pregnancy. Infection during the first trimester of pregnancy is most likely to cause severe fetal damage . In the third trimester the risk of fetal damage decreases to around 10 per cent. Severely infected infants may have ventriculomegaly or microcephaly, chorioretinitis and cerebral calcifi cation. These features may be detected on ultrasound scan.
Management
The diagnosis of primary infection with toxoplasmosis during pregnancy is made by the Sabin-Feldman dye test.. If suspicion of congenital toxoplasmosis has arisen because of an abnormal ultrasound scan of the fetus, an amniocentesis can be performed. Polymerase chain reaction (PCR) analysis of amniotic fluid is highly accurate for the identification of T. gondii. Spiramycin treatment can be used in pregnancy (a 3-week course of 2–3 g per day). If toxoplasmosis is found to be the cause of abnormalities detected on ultrasound scan of the fetus, then termination of pregnancy can be offered.
Cytomegalovirus
Infective organism Cytomegalovirus (CMV) is a DNA herpes virus. It is transmitted by respiratory droplet transmission and is excreted in the urine.
The incidence of infection in pregnancy is estimated to be around 1–2 per cent of pregnancies. Clinical features
Primary infection often produces no symptoms or mild non-specific flu-like symptoms in the mother. The diagnosis is often made after abnormalities are seen in the fetus on ultrasound scan. The main features seen in an affected fetus are FGR, microcephaly, ventriculomegaly, ascites or hydrops. Some fetuses which are infected may not show any features on ultrasound, but may later be found to have neurological damage such as blindness, deafness or developmental delay. The neonate can also be anaemic and thrombocytopenic, with hepatosplenomegaly, jaundice and a purpural rash.
Management
A serological diagnosis can be made by demonstrating the development of CMV antibodies in a seronegative woman, who initially develops CMV IgM antibody, and subsequently IgG antibody. If there is a suspicion that the fetus may be infected, amniotic fluid can be tested for the virus by PCR. Since the virus is excreted in fetal urine it can be found in amniotic fluid. If abnormalities are detected on ultrasound and these are felt to be due to congenital CMV infection, termination of pregnancy should be offered. A much more difficult situation is when CMV infection is known to have occurred, but the fetus appears normal on ultrasound, as there is approximately a 20 per cent chance of neurological abnormality in the fetus. After infection the virus is excreted for weeks or months by adults and for years by infants.
Chickenpox
Infective organism Chickenpox is caused by the varicella zoster virus (VZV), a herpes virus which is transmitted by droplet spread.
Prevalence In the UK 90 per cent of adults are immune to chickenpox. However, contact with chickenpox is common in pregnancy and approximately one in 200 women will contract chickenpox during their pregnancy.
Clinical features
Non-immune pregnant women are more vulnerable to chickenpox and may develop a serious pneumonia, hepatitis or encephalitis. It can occasionally be fatal with the mortality rate being approximately five times higher in pregnant women than in non-pregnant adults. Pneumonia occurs in about 10 per cent of women with chickenpox and seems more severe at later gestations. It may also cause the fetal varicella syndrome (FVS) or varicella infection of the newborn.
Management
If women have not had chickenpox, they should be advised to avoid contact with it during pregnancy, and if they accidentally come into contact with it should advise their doctor or midwife about the exposure as soon as possible.
Testing for immunity
If a women reports that she has been in contact with chickenpox, she should have a blood test for confirmation of VZV immunity, by testing for VZV IgG.
Management of the non-immune woman exposed to chickenpox
If the pregnant woman is not immune to VZV and she has had a significant exposure, she should be given varicella zoster immunoglobulin (VZIG) as soon as possible.
Management of chickenpox in pregnancy
Women with chickenpox should avoid contact with susceptible individuals. Symptomatic treatment and hygiene is advised to prevent secondary bacterial infection of the lesions. oral aciclovir 800 mg five times per day be prescribed for pregnant women with chickenpox if they present within 24 hours of the onset of the rash If the woman smokes cigarettes, has chronic lung disease, is taking corticosteroids or is in the latter half of pregnancy, a hospital assessment should be considered, even in the absence of complications. Women hospitalized with varicella should be nursed in isolation from babies or potentially susceptible pregnant women or non-immune staff. Delivery during the viraemic period may be extremely hazardous. The maternal risks are bleeding, thrombocytopenia, disseminated intravascular coagulopathy and hepatitis. There is a high risk of varicella infection of the newborn with significant morbidity and mortality. Supportive treatment and intravenous aciclovir is therefore desirable, allowing resolution of the rash and transfer of protective antibodies from the mother to the fetus.
The fetus
Spontaneous miscarriage does not appear to be increased if chickenpox occurs in the first trimester. FVS is characterized by one or more of the following:
• skin scarring in a dermatomal distribution;
• eye defects (microphthalmia, chorioretinitis, cataracts); •
hypoplasia of the limbs;
• neurological abnormalities (microcephaly, cortical atrophy, developmental delay and dysfunction of bowel and bladder sphincters).
Maternal infection around the time of delivery
If maternal infection occurs at term, there is a significant risk of varicella of the newborn. Elective delivery should normally be avoided until 5–7 days after the onset of maternal rash to allow for the passive transfer of antibodies from mother to child
Parvovirus
Infective organism Parvovirus is a relatively common infection in pregnancy, and is spread by droplet infection.
Incidence Fifty per cent of women at childbearing age are immune to PVB19 infection and therefore 50 per cent are susceptible to infection during pregnancy
Clinical features
In adults, symptoms are a mild flu-like illness. In children it may cause a characteristic rash (slapped cheek syndrome). In the fetus it can cause an aplastic anaemia. The anaemic fetus may then become hydropic due to high output cardiac failure and liver congestion. This is the most common presentation during pregnancy and is seen on ultrasound scan..
Management
The diagnosis is made by demonstrating seroconversion of the mother, who develops IgM antibodies to parvovirus, having previously tested negative. A hydropic fetus may recover spontaneously as the mother and fetus recover from the virus, or may require treatment by in utero transfusion. f the anaemia is treated by in utero transfusion, the fetus can make a complete recovery. Parvovirus does not cause neurological damage, and if the fetus survives the anaemia, there can be a completely normal outcome.
Listeria
Infective organism Listeria monocytogenes is an aerobic and facultatively anaerobic motile Gram-positive bacillus
Incidence The incidence of listeria infection in pregnant women is estimated at 12 per 100 000 compared to 0.7 per 100 000 in the general population. Contaminated food is the usual source of infection. Usual sources include unpasteurized milk, ripened soft cheeses and pâté.
Clinical features
Pregnant women with listeriosis most commonly suffer from a flu-like illness with fever and general malaise. About a third of women may be asymptomatic. Transmission to the fetus may either occur via the ascending route through the cervix, or transplacentally secondary to maternal bacteraemia. Approximately 20 per cent of affected pregnancies result in miscarriage or stillbirth. Premature delivery may occur in over 50 per cent. Neonates may have respiratory distress, fever, sepsis or neurological symptoms and the overall neonatal mortality rate has been estimated at 38 per cent.
Management
The diagnosis of listeria depends on clinical suspicion and isolation of the organism from blood, vaginal swabs or the placenta. For women with listeriosis during pregnancy, intravenous antibiotic treatment (ampicillin 2 g given every 6 hours) is indicated.
Herpes
Infective organism Herpes simplex virus (HSV) is a double-stranded DNA virus. There are two viral types, HSV-1 and HSV-2. The majority of orolabial infections are caused by HSV-1. These infections are usually acquired during childhood through direct physical contact such as kissing. Genital herpes is a sexually transmitted infection and is most commonly caused by HSV-2. However, there is an increasing Incidence Genital herpes is the most common ulcerative sexually transmitted infection in the UK. Neonatal herpes is a viral infection with a high morbidity and mortality which is most commonly acquired at or near the time of delivery due to contact with infected secretions. It is rare, with an incidence of 1 in 60 000 live births.
Clinical features
Genital herpes presents as ulcerative lesions on the vulva, vagina or cervix. A primary infection may be associated with systemic symptoms and may cause urinary retention. Neonatal herpes may be caused by HSV-1 or HSV-2, as either viral type can cause genital herpes. Almost all cases of neonatal herpes occur as a result of direct contact with infected maternal secretions, Neonatal herpes is classifi ed into three subgroups: disease localized to skin, eye and/mouth, local central nervous system disease (encephalitis alone) and disseminated infection with multiple organ involvement).
Management
A swab for viral detection should be used. The use of aciclovir is associated with a reduction in the duration and severity of symptoms and a decrease in the duration of viral shedding.
Primary infections
Caesarean section should be recommended to all women presenting with primary episode genital herpes lesions at the time of delivery, or within 6 weeks of the expected date of delivery. For women who develop primary genital herpes lesions within 6 weeks of delivery and who opt for a vaginal birth, rupture of membranes should be avoided and invasive procedures such as fetal scalp electrodes, or fetal scalp pH measurement should not be used. Intravenous aciclovir given intrapartum to the mother and subsequently to the neonate may be considered. The neonatologist should be informed and may advise acyclovir treatment of the baby.
Recurrent episodes
A recurrent episode of genital herpes occurring during the antenatal period is not an indication for delivery by Caesarean section. Women presenting with recurrent genital herpes lesions at the onset of labour should be advised that the risk to the baby of neonatal herpes is very small (1–3 per cent).
Group B streptococcus
Infective organism Group B streptococcus (GBS) (Streptococcus agalactiae) is a Gram-positive coccus frequently found as a vaginal commensal. It can cause sepsis in the neonate and transmission can occur from the time the membranes are ruptured until delivery.
The incidence of early-onset GBS disease in the UK is 0.5 per 1000 births. The mortality from early-onset GBS disease in the UK is 6 per cent in term infants and 18 per cent in preterm infants.
’ Clinical features
The mother will not have symptoms as GBS is a common vaginal commensal. An infected neonate may demonstrate signs of neonatal sepsis including sudden collapse, tachypnoea, nasal flaring, poor tone, jaundice, etc
Management
Antenatal If GBS is detected incidentally, antenatal treatment is not recommended as it does not reduce the likelihood of GBS colonization at the time of delivery.
Intrapartum antibiotic prophylaxis
intrapartum antibiotic prophylaxis
• Intrapartum fever
• Prolonged rupture of membranes (PROM) 18 hours
• Prematurity 37 weeks •
Previous infant with GBS •
Incidental detection of GBS in current pregnancy
• GBS bacteruria.
It is recommended that intravenous penicillin be given as soon as possible after the onset of labour and 4-hourly until delivery. Clindamycin should be given intravenously 8-hourly to those allergic to penicillin.
Chlamydia
Infective organism Chlamydia trachomatis is an obligate intracellular organism.
Prevalence Chlamydia is the most common sexually transmitted organism in the UK and USA. Between one in 8–10 men and women who are sexually active and under 25 years old screen positive for Chlamydia
Clinical features During pregnancy chlamydia is frequently asymptomatic in the pregnant woman. Infection with chlamydia is associated with preterm rupture of membranes, preterm delivery and low birthweight. Transmission to the fetus occurs at the time of delivery and can cause conjunctivitis and pneumonia.
Management Treatment with azithromicin or erythromycin is recommended. Tetracyclines such as doxycycline should be avoided if possible during pregnancy. Appropriate contact tracing can be arranged via a genitourinary medicine clinic.
Gonorrhoea
Infective organism Neisseria gonorrhoeae is a Gram-negative diplococcus. In the UK it is the second most common bacterial sexually transmitted disease.
Clinical features Gonococcal infection in women is frequently asymptomatic, or women may present with a mucopurulent discharge or dysuria. Rarely, disseminated gonorrhoea may cause low grade fever, a rash and polyarthritis. There is an increased risk of coinfection with chlamydia, and an increased risk of preterm rupture of membranes and preterm birth. Transmission to the fetus occurs at the time of delivery and can cause opthalmia neonatorum.
Management
. Cephalosporins are effective against gonococcus, but empirical treatment for chlamydia should also be considered. Appropriate contact tracing can be arranged via a genitourinary medicine clinic.
HIV
Infective organism The HIV virus is an RNA retrovirus transmitted through sexual contact, blood and blood products, shared needles for i.v. drug users, vertical (motherto-child) transmission which mainly occurs in the late third trimester, during labour or delivery or breastfeeding.
Prevalence
The prevalence of HIV infection in pregnant women in London in 2001 was about 0.35 per cent
Screening
Routine antenatal screening has increased detection rates and new treatments have increased life expectancy. In the UK, all pregnant women should be offered screening for HIV early in pregnancy because appropriate antenatal interventions can reduce maternal-to-child transmission of HIV infection from 25 to 30 per cent to less than 2 per cent.
Clinical features
Infection with HIV begins with an asymptomatic stage with gradual compromise of immune function eventually leading to acquired immunodefi ciency syndrome (AIDS). The time between HIV infection and development of AIDS ranges from a few months to as long as 17 years in untreated patients. Management The principal risks of mother-to-child (vertical) transmission are related to maternal plasma viral load, obstetric factors and infant feeding .
Interventions to reduce the risk of HIV transmission can reduce the risk of vertical transmission from 25 to 30 per cent to less than 2 per cent:
• anti-retroviral therapy, given antenatally and intrapartum to the mother and to the neonate for the first 4–6 weeks of life
• delivery by elective Caesarean section
• avoidance of breastfeeding.
Hepatitis B
Infective organism The hepatitis B virus (HBV) is a DNA virus that is transmitted mainly in blood, but also in other body fluids such as saliva, semen and vaginal fluid. Drug users who share needles are at high risk. In the UK, approximately one in 1000 people are thought to have the virus. The prevalence of hepatitis B surface antigen (HBsAg) in pregnant women in the UK has been found to range from 0.5 to 1 per cent.
. Screening Serological screening for HBV should be offered to pregnant women so that effective post-natal intervention can be offered to infected women to decrease the risk of mother-to-child transmission.
Mother-to-child transmission of the HBV is approximately 95 per cent preventable through administration of vaccine and immunoglobulin to the baby at birth. To prevent mother-to-child transmission, all pregnant women who are carriers of HBV need to be identified.
. Clinical features Hepatitis B is a virus that infects the liver, but many people with hepatitis B viral infection have no symptoms. The HBV has an incubation period of 6 weeks to six months.
Management Women who screen positive for hepatitis B should be referred to a hepatologist for ongoing monitoring for the long-term consequences of chronic infection, for example hepatocellular carcinoma. To prevent vertical transmission of hepatitis B, a combination of hepatitis B immunoglobulin and hepatitis B vaccine may be given.
Hepatitis C
Infective organism The hepatitis C virus (HCV) is an RNA virus. Acquisition of the virus occurs predominantly through infected blood products and injection of drugs. It can also occur with tattooing and body piercing.
Motherto-child transmission can occur due to contact with infected maternal blood around the time of delivery, and the risk is higher in those coinfected with HIV.
Prevalence In the UK the overall antenatal prevalence has been estimated to be around 1 per cent, with regional variation. The risk of mother-to-child transmission of HCV increases with increasing maternal viral load.
Screening Current recommendations are that pregnant women should not be offered routine screening for HCV. This is because there is a lack of evidence-based effective interventions for the treatment of HCV in pregnancy, and a lack of evidence about which interventions reduce vertical transmission of HCV from mother to child.