Chauhan AR
Maternal
infections have been associated with pregnancy since time immemorial, be it the
ubiquitous throat infection or full-blown septicemia; however despite pregnancy
being an “immune-compromised state”, maternal response to infections in
pregnancy is usually the same as in non- pregnant adults. Some infections may
be more dangerous in pregnancy and have short and long-term devastating sequel
like pregnancy wastage, preterm labor, fetal death, and maternal -fetal
transmission leading to lifelong stigmata.
Infections
in pregnancy may be classified based on the route of infection and type of
organism (viral, bacterial, protozoal). However the diagnostic approach is
usually based on symptomatology, gestation age and immune status of the mother.
Both humoral and cell mediated immunity have a significant role; the former
tackles extracellular pathogens and the latter, intracellular pathogens.
Pregnant women may be at risk, exposed to, or contract a viral fever with rash,
where the management varies from simple observation and counseling to medical
termination of pregnancy, for example in cases of rubella in first trimester.
Infections
usually have a “vertical transmission”, a term that refers to the unique
relationship between mother and fetus. Transmission may be intrauterine
(transplacental), perinatal (just prior to or during delivery via hematogenous
route or genital tract), or postnatal through breast milk. Viruses like
rubella, cytomegalovirus (CMV), varicella zoster, HIV and parvovirus, bacteria
like syphilis, and protozoans like toxoplasma and malaria are all transmitted
via the placenta, while herpes simplex virus (HSV) and group B streptococcus
(GBS) usually ascend through the genital tract and infect the fetus.
The exact
impact on pregnancy varies widely: maternal reactions like high fever and
anemia can precipitate embryonic demise; teratogenicity may occur if fetal
insult occurs early in first trimester; non- specific fetal problems like IUGR,
hydrops, and microcephaly may be seen later in pregnancy with a number of viral
infections.
Congenital
infections may be transmitted in any trimester, but in general, fetal
affectation is more severe when the infection is acquired early in pregnancy,
resulting in abortion, fetal loss or teratogenicity; rubella infection is a
classic example with a well-defined syndrome of congenital malformations.
Fortunately the risk of transmission of infections is low in early gestation.
Conversely, though the rates of fetal infection are higher in later gestation,
the effects are not as severe and manifest as IUGR or developmental anomalies.
Routine
antenatal screening at the first prenatal visit using a battery of tests may
appear ideal, but is neither feasible nor routinely possible. A viable
compromise between the potential dangers of infection, resources available for
testing and maternal willingness for the same should be reached; the standard
minimum screen should include rubella IgG, hepatitis B surface antigen, and
serological tests for syphilis and HIV.
Ideally,
rubella non-immune women should be offered vaccination prior to conception, or
if screened during pregnancy, they should be counseled about viral fevers and
rash, especially in the first trimester. Current recommendation is to offer
measles – mumps –rubella (MMR) vaccine postnatally. Infants born to hepatitis B
positive mothers should be actively and passively immunized at birth to
decrease the risk of development of carrier state. Syphilis is still an
infection to be reckoned with; if untreated, there is an alarmingly high
perinatal mortality of 40% (25% of affected pregnancies result in stillbirth
and 14% in neonatal deaths). Despite WHO guidelines, syphilis screening is not
done in many underdeveloped countries with disastrous fetal consequences.
Penicillin remains the drug of choice.
In the
absence of any intervention, the risk of transmission of HIV from mother to
child is about 25- 30%; this can be reduced significantly to about 12% with
treatment. National AIDS Control Organization (NACO) recommends single dose
nevirapine during labor in treatment-naïve pregnant women with CD4 count
>250cells/mm3. For HIV positive pregnant women already on
antiretroviral therapy, their existing regimen should be continued; efavirenz
however should be avoided in the first trimester due to teratogenicity.
TORCH is
an acronym for congenital infections: Toxoplasmosis, Other infections
(syphilis, hepatitis B, Coxsackie virus, Epstein-Barr virus, varicella-zoster
virus, and human parvovirus), Rubella, CMV and HSV. TORCH infections are
usually the cause of isolated fetal loss and not recurrent losses, as is
mistakenly believed. Routine screening is not recommended except for rubella
IgG, and CMV screening for women who work in neonatal ICUs, child care
facilities or dialysis units.
Diagnosis
of TORCH and other infections is based on maternal symtomatology and serology.
Flu- like symptoms with fever, myalgia and lymphadenopathy may point to primary
CMV or toxoplasma infection, or listeriosis, if associated with diarrhea.
Listeriosis is an uncommon foodborne illness which can be prevented with simple
advice like meticulous washing of raw food, adequate cooking, and hand washing.
Presence of maculopapular rash along with fever and arthralgia should raise the
suspicion of rubella or parvovirus infection. Parvovirus infection causes
erythema infectiosum, and is responsible for fetal loss and hydrops;
intrauterine transfusion greatly improves the fetal outcome. Varicella rash is
usually a typical vesicular rash and the diagnosis is clinical. Urinary tract
infection, HSV, gonorrhea and Chlamydia should be ruled out when patients
present with genitourinary symptoms, loin pain, fever, genital ulcers and
vaginal discharge. Varicella and herpes infection in pregnancy may warrant
treatment with acyclovir, which though not routinely recommended in pregnancy,
may be used to reduce maternal morbidity. Patients with HSV infection at term
should be delivered through cesarean section to avoid the risk of neonatal
sepsis and encephalitis, which may be fatal.
Fetal diagnosis of infection may be confirmed with chorion villous
sampling or amniocentesis in select cases.
Malaria is
endemic in many parts of India
The
vicious cycle between maternal infection and preterm labor, as both cause and
result, has been well documented. Infections like bacterial vaginosis,
gonorrhea and chlamydia increase the risks of preterm labor and premature
rupture of membranes. Treatment with antimicrobials may improve fetal outcome
by decreasing chances of chorioamnionitis and hence neonatal sepsis and NICU
admission.
Infections
of the urinary and reproductive tracts during pregnancy are likely to be
underplayed by both the patient and her obstetrician. UTI, bacterial vaginosis
and asymptomatic bacteriuria may have far- reaching consequences for both
mother and fetus, ranging from mild fever and
discomfort to pyelonephritis,
higher incidence of PROM and subsequent chorioamnionitis, and neonatal
septicemia. During delivery, GBS infection of the reproductive tract can
transmit and manifest as neonatal sepsis. Hence adequate antibiotic prophylaxis
and treatment are indicated.
Maternal
periodontal disease is emerging as a new preventable infection associated with
preterm deliveries and low birth weight babies; however evidence is
conflicting. Improvement in standards of periodontal care and treatment during
pregnancy may help combat this trend.
Other
emerging infectious diseases include the not so recent scare of SARS (severe
acute respiratory syndrome), viral hemorrhagic fevers like Lassa fever and
Ebola which are more severe in pregnancy, and Psittacosis, a flu-like illness
with fever, headache, and atypical pneumonia. Pneumocystis jiroveci, previously
known as Pneumocystis carinii, responsible for pneumonia in immune-compromised
patients, may be more severe in pregnancy and vertically transmitted by
HIV-positive patients to their offspring.
It is these emerging infections against which we
need to be well informed and vigilant, so as to provide adequate protection to
our expectant mothers and their unborn babies. It gives me great pleasure to
present to you the June issue of our Journal, which features an interesting
case of HSV in pregnancy.