Neonates/newborns infections

Neonatal HSV infection occurs in 1 3500 to 1 5000 deliveries in the United States. It is most commonly acquired by intrapartum contact with infected maternal genital secretions and is usually caused by HSV type 2. In tlie newborn there are three general presentations of the disease skin, eye, and mouth disease accounts for approximately 45% of infections, encephalitis accounts for 35%, and disseminated disease accounts for 20%. As disseminated disease is often associated with neurological disease, CNS disease occurs in about 50% of newborns with neonatal HSV infection. 

It has the ability to cross the placenta and therefore provides a major line of defence against infection for the newborn. This can be reinforced by transfer ofcolostral IgG across the gut mucosa of the neonate. It diffuses readily into the extravascular spaces where it can act in the neutralization of bacterial toxins and can bind to microorganisms enhancing the process of phagocytosis (opsonization). This is due to the presence on the phagocytic cell surface of a receptor for Fc. 

Herpetic conjunctivitis is usually a manifestation of primary HSV infection, which generally occurs in children between the ages of 6 months and 5 years. Most cases of herpetic ocular infection result from the nonvenereal form of the virus (HSV-1). Ocular infection with HSV-2 can occur in both newborns and adults. Infection may result from contact with the virus in the infected birth canal (herpetic neonatal conjunctivitis) or from autoinoculation after sexual contact with an infected partner. 

GBS remains a serious cause of neonatal infection. GBS disease in the newborn is classified as either early disease, which occurs within 1 week of fife and usually presents as a sepsis syndrome or pneumonia, or late disease, which is defined as that presenting at greater than 1 week of life and that presents most commonly as sepsis or meningitis. 

Infants born of infected women may come in contact with the virus as they move down the birth canal, and this may result in a severe or even life-threatening neonatal infection. It is estimated that 1 in 350 infants is delivered vaginally during viral shedding, but the incidence of severe herpetic infection in the newborn is approximately 1 in 20,000. ... 

With active prevention efforts in the 1990s, the incidence of early-onset disease is now 0.5 cases per 1000 births, decreased from 1.8 cases per 1000 births. There has not been any change in the incidence of late-onset group B Streptococcus disease, which remains consistent at 0.35 cases per 1000 births. The consequences of neonatal infections include bacteremia, pneumonia, and meningitis in the newborn. The case-fatality rate is approximately 4%. ... 

While prenatal diagnosis is based on the detection of T. gondii in the amniotic fluid, neonatal screening is based on the detection of parasites in the placenta and on the detection of IgM and IgA antibodies in newborns. PCR for the detection of parasite DNA in amniotic fluid has improved the sensitivity of prenatal diagnosis (Bessieres et ah, 2009). The accurate diagnosis of congenital toxoplasmosis is essential, since if the mother is treated it would reduce the probability of fetal infection by 50% (Desmonts and Couvreur, 1974). 

A significant finding in the experiments of Mills (1979) was the observation that PMN from full term infants have both depressed respiratory burst activity as measured by CL and depressed bactericidal activity while ingestion remains normal. The author s results demonstrated that neonatal PMN were comparable to adult PMN in the clearance of low PMN-bacteria ratios but depressed at high ratios. CL correlated well with these observations and is important to the understanding of newborn infant susceptibility to infection. 

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