What is chicken pox and herpes zoster in pregnant women?
Chickenpox is a highly contagious disease characterized by epidemic rises in the incidence in the winter-spring period. Chickenpox susceptibility is universal, with the exception of the children of the first months of life from mothers who previously had chickenpox. The source of infection is a person who has chickenpox or shingles (from the moment of rash until the vesicles dry up).
The spread of chickenpox occurs through airborne droplets, contact and transplacental. After chickenpox, strong immunity develops, repeated cases of this disease are extremely rare. At puberty, the proportion of infected is 90%. Only 5–7% of women of childbearing age are seronegative and susceptible to chickenpox. Herpes zoster is a secondary infection that develops as a result of the activation of a latent WZ infection in people who have previously had chickenpox. Pregnant women are at risk because of gestational decline in immunity. In various studies, it was found that for 1,000 births, there are 5 cases of chicken pox and 2 cases of herpes zoster.
In connection with the physiological decline in immunity during pregnancy, the probability of infection with chickenpox in women who have not had chickenpox (5–6%) and activation of latent infection in the form of herpes zoster increases. In this case, the danger to the pregnant woman is not the WZ infection itself, but the complications caused by it: pneumonia, intrauterine infection of the fetus, fetal loss syndrome. Chickenpox in pregnant women is complicated by WZ-pneumonia in 20% of cases. Pneumonia develops when chickenpox is infected in the later stages of gestation and quickly leads to respiratory failure and secondary bacterial complications. Mortality from WZ-pneumonia in the whole population is 10-20%, but among pregnant women it reaches 45% without specific therapy. In the treatment of acyclovir mortality is reduced to 10-11% in both pregnant and outside pregnancy.
Chickenpox can be transmitted to the fetus by transplacental and transcervical ascending paths during pregnancy and during labor and postnatally by airborne droplets. In utero, the virus is transmitted to the fetus from a mother with chickenpox in 25% of cases. The possible effect of infection on the fetus depends on the duration of the pregnancy and the severity of the infection in the mother. The risk for the fetus and newborn is approximately 8%. In this case, the complications of pregnancy are spontaneous miscarriages and non-developing pregnancies in the first half of pregnancy in 3-8% of cases and fetal varicella syndrome. If the disease in a pregnant woman has arisen in the first trimester, 5–12% of infected newborns have congenital defects – atrophy of the extremities, scars on the skin, rudimentary fingers, atrophy of the cerebral cortex, as well as paralysis and convulsive syndrome. It is believed that the frequency of embryopathy and fetopathy after varicella in the first 20 weeks of pregnancy is 2%. In case of illness after 25 weeks, only isolated cases of fetal malformations are described.
It is dangerous to infect a pregnant chicken pox on the eve of childbirth, when a sufficient titer of protective specific antibodies does not have time to be transplacentally transmitted to the fetus. If a pregnant woman falls ill less than 10 days before giving birth, the fetus can develop severe lesions – neonatal chicken pox. Mortality in newborns in this case reaches 21%. In relation to mortality, the time of appearance of the primary exanthema in the newborn plays an important role. If a child has an exanthema at the age of 5-10 days, then serious complications are expected and the mortality rate is 21%. In children whose rash is already visible in the first 5 days of life, severe complications and deaths are not observed.
In contrast to chickenpox, there is no complication of fetal complications in the case of herpes zoster disease, since the mother has specific protective IgG antibodies and does not have viremia.
Causes of Chicken Pox and Herpes Zoster in Pregnant Women
The varicella-zoster virus (WZ infection) belongs to the herpesvirus family. Chickenpox in its structure and function resembles other herpes viruses and is the causative agent of two different clinical diseases – chickenpox and shingles. The virus is easily transmitted from a sick person to a healthy one, so the vast majority of the adult population has immunity after previous primary infection – chickenpox. After recovery, the pathogen remains in the body and persists for a long time in the sensory nodes. Activation of a latent virus, which may occur decades later, leads to the development of shingles.
Pathogenesis during varicella and herpes zoster in pregnant women
The incubation period for chickenpox is 21 days. Contagious patients become 1–2 days before the rash and remain so exactly one week. In adults in the prodromal period fever and malaise are observed. Then a characteristic vesicular-papular rash appears. The more abundant the rash, the more common the general manifestations of the infection (fever, headache, sleep disturbance). Severe forms of the disease with abundant rashes, gangrenous, hemorrhagic elements of the rash, high fever and damage to internal organs are found in adults and children with weakened immunity. Chickenpox complications are rare and are mainly associated with secondary bacterial infections. Serious complications are chickenpox pneumonia and CNS lesions in the form of cerebellar ataxia and encephalitis. In adults, chickenpox pneumonia is observed in 20% of cases of chicken pox.
Herpes zoster is a disease with neurodermal tropism, characterized by unilateral neurological pain along the roots of the affected spinal and cranial nerves, accompanied by the appearance of a vesicular rash. Most often affects the thoracic spinal nodes and the roots of the trigeminal nerve. With the involvement of the sympathetic and parasympathetic nodes in the process there is dysfunction of the gastrointestinal tract, urinary retention, trophic disorders. It is possible to save pain for several months – postherpetic neuralgia. Localization of pain corresponds to the affected nerves and has a shingles character. Other complications are motor paralysis, meningoencephalitis, damage to the visual and pre-vesicular (auditory) nerves (Hunt syndrome).
The symptoms of Chicken Pox and herpes zoster in pregnant women
Chickenpox during pregnancy is characterized by the following features:
- with chickenpox during pregnancy, the risk for the fetus and newborn is 8%;
- if the pregnant woman got sick in the first trimester, congenital varicella-zoster syndrome (atrophy of the extremities, scarring on the skin, rudimentary fingers, atrophy of the cerebral cortex, eye defects, paralysis and convulsive syndrome) is noted in 5% of newborns;
- if the pregnant woman got sick in the first 20 weeks of gestation, 2% of newborns have congenital varicella syndrome;
- in each case of chickenpox for up to 20 weeks, an ultrasound scan is recommended; if “unusual data” is detected, an amniocentesis and cordocentesis can be performed to confirm fetal infection;
- confirmation of fetal infection is not an absolute indication for abortion;
- if the pregnant woman got sick less than 10 days before giving birth, the neonatal chicken pox, complicated by encephalitis, hepatitis, pneumonia, occurs in the newborn.
Diagnosis of chicken pox and herpes zoster in pregnant women
The diagnosis of varicella is established according to the clinical picture. In addition, you can examine the contents of the vesicles by PCR on WZ DNA. Serological diagnosis is carried out by determining specific IgG-and IgM-antibodies, IgM appear on the 4-8th day from the onset of the disease and persist up to 3 months. In the future, there are IgG, which are defined in the blood for life. Their titer is examined to confirm the presence of immunity to WZ.
Prenatal diagnosis. It is recommended that all pregnant women who have had chickenpox in early pregnancy be carried out an ultrasound scan in the 22-23rd week of pregnancy to detect fetal defects that are typical of WZ infection. With unusual ultrasound data, it is necessary to detect DNA by PCR in fetal blood and amniotic fluid. To establish a fetal infection in the 16-20th week of pregnancy, you can explore the amniotic fluid. In case of confirmation of the diagnosis of absolute indications for abortion, there is still no, only if there are ultrasound data on serious fetal malformations, it is necessary to offer the woman an abortion.
Treatment of chicken pox and herpes zoster in pregnant women
There is still no data on the use of antiviral therapy for varicella in pregnant women. Since chickenpox is less sensitive to acyclovir than HSV, it is necessary to increase the dose and administer the drug parenterally. In severe cases, pneumonia is prescribed acyclovir at 10 mg / kg every 8 hours intravenously for 10 days. In severe cases of herpes zoster during pregnancy, acyclovir can be used in the second and third trimesters, and in very severe cases, in the first trimester. The introduction of specific VVZ-immunoglobulin during pregnancy is carried out with the aim of passive immunization, and with the aim of preventing such serious complications of varicella as varicella pneumonia.
Events held in childbirth. If chicken pox is suspected, delivery should be postponed for 3–4 days so that maternal IgG antibodies, which increase by about 5–6 days after acute chicken pox, can be transmitted to the fetus and, accordingly, to the newborn. If it was not possible to conduct tocolysis, immediately after birth, WZ-immunoglobulin is administered to the child. With massive rash of chickenpox elements on the genital organs of the woman less than 5 days ago, the question of caesarean delivery may be raised to prevent intranatal infection.
After giving birth, women with chickenpox or herpes zoster are isolated in special boxes of the observational department. Newborns are prescribed a prophylactic course of acyclovir and WZ-immunoglobulin. Passive immunization is carried out using intramuscular injection of varicellon at a dose of 0.2-0.4 ml / kg or intravenous administration of varitect at a dose of 1-2 ml / kg. The child is isolated from the mother until the danger of infection has passed. These newborns are observed for 14 days even in the absence of symptoms of infection. With the development of chicken pox in a newborn, a therapeutic course of acyclovir is prescribed in a dose of 5 mg / kg every 8 hours intravenously for 5-7 days. Remove the quarantine only after covering the lesions with crusts. Compulsory breastfeeding of these newborns is recommended, as protective anti-TH-VVZ antibodies are transmitted with mother’s milk.
Fetal varicella syndrome includes:
- skin lesions (scars, lack of skin);
- skeletal abnormalities (unilateral hypoplasia of the upper and lower extremities, chest hypoplasia, rudimentary fingers, clubfoot);
- CNS malformations (microcephaly, anophthalmia, anisocoria, optic nerve atrophy, cataracts, and chorioretinitis);
- intrauterine growth retardation and muscle hypoplasia.
When a woman is infected on the eve of birth, neonatal chicken pox can develop in a newborn after birth. This disease becomes possible if the seronegative woman has been in contact with a chicken pox patient in the last 3 weeks of pregnancy. Neonatal chickenpox manifests itself in the first 10 to 12 days of life of the newborn, as it is transmitted transplacentally on the eve of the birth. If the rash appeared 12 days after delivery, then this is more likely to indicate postnatal infection. This form of the disease has a milder course, since newborns in most of them have protective maternal immunity. The most severe infection occurs in children whose mothers are sick in the last 5 days of pregnancy and the first 2 days after birth. Mortality among these children is 20-30%. In general, the incidence of severe complications in neonatal varicella is 20-50%.
Laboratory diagnosis of chickenpox using the PCR method is needed to confirm the diagnosis of congenital varicella syndrome. To confirm the association of maternal varicella and congenital fetal abnormalities, the following criteria are taken into account:
- the disease of a woman with chickenpox during pregnancy;
- the presence of congenital skin lesions in several dermatomes and / or neurological disorders, eye lesions and limb hypoplasia;
- confirmation of the presence of intrauterine WZ infection by determining viral DNA in the fetus, the presence of specific IgM, the persistence of specific IgG after 7 months;
- the presence of congenital neonatal herpes zoster or its appearance in childhood.
Prevention of Chicken Pox and Herpes Zoster in Pregnant Women
A live WZ vaccine has been created. It is recommended in childhood, as well as in seronegative women planning pregnancy. After vaccination, pregnancy is allowed after 3 months. Vaccination is prohibited in pregnant women, however, the accidental introduction of a vaccine to a pregnant woman is not an indication for termination of pregnancy.
Seronegative pregnant women who have had contact with a chicken pox patient are administered immunoglobulin no later than 72 hours after contact. Passive immunization is carried out using intramuscular injection of varicellon at a dose of 0.2-0.4 ml / kg or intravenous administration of varitect at a dose of 1-2 ml / kg. With the timely introduction and optimal dosage of immunoglobulin, infection is prevented in only 48% of cases. Asymptomatic infection is observed in 6% of pregnant women, and in the remaining cases, varicella proceeds in a weak form.
Therefore, when contacting WZ during pregnancy, the following is necessary.
- Examination of a pregnant for IgG to WZ (5-7% of pregnant women are seronegative).
- The introduction of immunoglobulin against WZ – varicellon intramuscularly at a dose of 0.2-0.4 ml / kg; Variect intravenously at a dose of 1-2 ml / kg in the first 72 hours after contact.
- With chickenpox pregnant for a period of 37 weeks or more – holding tocolysis.
It should be noted that a favorable perinatal outcome can be expected with a high titer of maternal IgG to WZ; herpes zoster in a pregnant woman does not pose a threat to the fetus.