Perinatal Infections Flashcards
Infection routes
Ø1. Transcervically (ascending)
Ø2. Transplacentally (Hematologic)
Ø3. Combination 1+2
ØThe most common means of infection of the fetus is via the blood stream (transplacentally)
ØLess common means of infections is
via cervix (Transcervically)
Vertically transmitted ( mother to child ) infections of the fetus and newborn can generally be divided 2 major categories:
- Congenital infections : which are transmitted to the fetus in utero.
- Perinatal infections : which are acquired intrapartum or in the postpartum period
Facts about congenital infections
- The time to provide information to mothers about these infections is before pregnancy begins, because this is the best time for preventive measures.
- The first trimester is usually the most dangerous time to acquire these infections.
- Infection in the mother can often be accompanied by trivial or even no symptoms, and the condition may not be remembered or diagnosed.
- Infection in the mother does not always mean that the baby will be affected.
- Some infections can be avoided by the mother through simple measures, e.g. immunization (Rubella, VZV ) during childhood and before pregnancy.
The most common organisms causing Congenital Infections
Etiologic Agents (TORCH):
- Toxoplasmosis
- Others [syphilis, tuberculosis, listeriosis ]
- Rubella
- Cytomegalovirus
- Herpes simplex
Other common congenital infections not caused by TORCH
- Hepatitis B
- Parvovirus B19
- HIV
- Campylobacter fetus.
- Fungi: Candida albicans.
- Parasites: Plasmodium spp., Trypanosoma cruzi
TORCH
ØTORCH group of infections are grouped together because they evoke similar clinical and pathologic manifestations:
- Fever
- Encephalitis
- Chorioretinitis
- Hepatosplenomegaly
- Pneumonitis
- Myocarditis
- Hemolytic anemia
- Vesicular or hemorrhagic skin lesions
Hematologic infections
Usually through chorionic villi ØToxoplasma ØMalaria ØMost of Viral Infections ØBacterial: Listeria, Treponema ØHIV usually through maternal-to-fetal transfusion
Transcervical Infections
Acquired in Utero or around the time of birth (Premature Rupture of Membranes)
1. Inflammation of placental membranes→
2. Increased level of prostaglandins →
3. Contractions and labor →
4. Inhalation of infected amniotic fluid by fetus/newborn→
5. Pneumonia →Sepsis →Meningitis →
6. Death
MC transcervically entered pathogens are:
Bacterial (Streptococcus Group B!!!!)
Viral (Herpes Simplex II) Infections
Syndromes in neonates caused by congenital infections
Toxoplasma gondii
Hydrocephalus, diffuse intracranial calcification, chorioretinitis
Rubella virus
Cardiac defects, sensorineural hearing loss, cataracts
Cytomegalovirus
Microcephalus, periventricular calcification
Varicella - zoster virus
Limb abnormalities, cicatricial (scar) lesions
Erythrovirus B19 (Parvovirus B19) Diffuse edema (in utero hydrops fetalis)
Herpes simplex virus
Vesicular lesions, keratoconjunctivitis
Treponema pallidum
Bullous, macular, and eczematous skin lesions involving the palms and the soles; rhinorrhea, dactylitis osteochondritis and periostitis
CMV- cytomegalovirus
ØCMV is a congenital and opportunistic pathogen that usually produces asymptomatic infection
ØFetus and immunocompromized patients are particularly vulnerable to CMV destructive effects
Ø CMV infects 0.5% to 2.0% of all fetuses and injures 10% to 20% of those infected, making it the most common congenital pathogen
ØThe most common cause of in-utero infection.
Ø Fetal infection is greatest ( 40% ) during primary maternal infection & rarely during recurrent infection.
Ø Only 10% of infants born with congenital infections are symptomatic at birth.
Ø Infection during 1st trimester usually causes severe affection.
Epidemiology: CMV
ØCMV spreads:
- from person to person by contact with infected secretions and bodily fluids -children spread it in saliva or urine, while transmission among adolescents and adults is primarily through sexual contact
- to fetus across the placenta
CMV pathogenesis
ØWhen an infected pregnant woman passes CMV to her fetus, the fetus is not protected by maternally derived antibodies and the virus invades fetal cells
ØDue to the little initial immunologic response, there is a widespread necrotic and inflammatory changes in various tissues
CMV PATHOLOGY of FETUS
Most commonly involves: 1.Brain 2.Inner ears 3.Eyes 4.Liver 5.Bone marrow Signs: 6.Microcephaly 7.Hydrocephalus 8.Cerebral calcifications 9.Hepatosplenomegaly and jaundice.
CLINICAL FEATURES of Congenital CMV
ØCongenitally acquired CMV has diverse clinical presentations:
- Severe disease causes fetal death in utero, conspicuous CNS lesions, liver disease and bleeding problems
- Moderate form causes fetal growth restriction (FGR), microcephaly with periventricular calcifications
- Most congenital CMV infections do not produce gross abnormalities, but manifest as subtle neurologic or hearing defects, which may not be detected until later in life.
- If the infection is acquired during labour the symptoms may appear after an incubation period of 4-12 wk or pass unnoticed only to be discovered with hearing abnormalities later.
Diagnosis and treatment of CMV
Ø Culture.
Ø PCR.
Ø CMV IgM & IgG.
Ø CT scan, abnormal CT predicts high
probability of CNS sequalae.
Treatment:
Gancyclovir – valgancyclovir
Prevention:
Ø Attenuated virus vaccine.
Ø Hyper immune CMV immunoglobulin.
