Introduction

More than 33 million people were living with HIV by the end of 1998. According to UNAIDS estimates, 22.5 million of these were in Africa (67%), and 6.7 million in South and Southeast Asia (20%). Close to six million new infections are occurring each year, with 10% of these in children, the majority as a result of mother-to-child transmission (MTCT) (UNAIDS, 1998). An estimated one and a half to two million HIV-infected women will become pregnant each year, with 1600 children each day infected by mother-to-child transmission.

In Europe, the increase in heterosexually acquired HIV infection in women of childbearing age has been paralleled by increasing numbers of infected children. Antenatal HIV prevalence in Europe is generally below 5 per 1000 deliveries, although variable: higher in selected groups and inner cities. In a number of countries in Africa south-of-the-Sahara, 10–25% of pregnant women are infected, with rates of over 40% reported in parts of Southern Africa (US Bureau of the Census, 1999; Stanecki & Way, 1999). Southeast Asia has seen a rapid rise in infection rates in some areas.

HIV infected children most commonly present early in life with non-specific clinical manifestations. About one-quarter of infected children will develop AIDS in the first year of life, but the progression of disease in the remainder is much slower. In developed countries about 75% of infected children are alive by age 5 years, and in developing countries about 40% (French Pediatric HIV Infection Study Group and European Collaborative Study, 1997). HIV/AIDS has increased infant and child mortality dramatically in the most affected African countries, and is expected to lead to a doubling of under-5 mortality by 2010 in southern African countries.

The virus

Cytomegalovirus (CMV) is an enveloped DNA virus and a member of the herpes family which also includes herpes simplex, Epstein–Barr and varicella-zoster viruses. Like other herpes viruses, once primary infection has occurred the virus establishes itself in the host in a latent form, possibly in peripheral blood mononuclear cells, and may periodically reactivate (Jafari et al., 1995). During active infection CMV is found in epithelial cells (Griffiths & Grundy, 1998). Infection is controlled by cellular and humoral immune responses, with the cellular responses being the most important and much of the tissue damage associated with CMV infection is probably due to the immune mediated inflammatory reaction to infected cells expressing CMV antigen (Griffiths & Grundy, 1998). CMV is probably transmitted through infected secretions coming into contact with mucous membranes, but not through intact skin. Droplet infection seems to play a minor role. The virus is unstable outside the body and is vulnerable to ordinary soaps, detergents, commonly used disinfectants and heat. Normal hygienic procedures should thus substantially reduce, or eliminate, the risk of transmission of infection.

Both primary and recurrent (with the same or a different strain) infections are associated with viral shredding in body fluids, including urine, saliva, semen, cervical secretions and breast milk. In healthy individuals symptoms of CMV infection are usually mild or not apparent and rarely cause serious illness. However, infection can be life threatening in immunocompromised individuals and in very premature infants, and when acquired in pregnancy it can result in fetal damage (Fig. 7.1).

Introduction

Hepatitis is a general term for inflammation of the liver due to a variety of causes, of which viruses are the most common, but which can also include toxic and auto-immune disorders. The consequences of liver disease in pregnancy, including maternal and fetal outcome, are beyond the scope of this chapter, which focuses on vertical transmission. Acute hepatitis in the mother must be distinguished from other types of liver disease, either unique to pregnancy, such as cholestasis of pregnancy, acute fatty liver of pregnancy and preeclampsia / HELLP syndrome, or pre-existing liver disease, such as cholelithiasis. Although a number of viruses, including herpes simplex and cytomegalovirus, can cause hepatitis, viral hepatitis refers to infections caused by the hepatitis viruses.

Six distinct hepatitis viruses are known: A, B, C, D, E and G, which are not easily distinguished on clinical grounds. Hepatitis A and E are transmitted by the faecal-oral route, and are not commonly transmitted vertically. However, they can cause either asymptomatic infection or fulminating acute hepatitis, notably for HEV in pregnant women. HBV, HCV, HDV and HGV are bloodborne agents, which can lead to chronic carriage, and subsequently to mother-to-child transmission. The clinical significance of HGV remains undetermined, and HDV is dependent upon co-infection with HBV for replication. Hence, HBV and HCV are the most important. They have similar epidemiological and clinical features, and in both infections, asymptomatic carrier mothers can be identified only if serologic testing is performed. Yet there are also important differences. HBV has been known for decades, has a high risk of mother-to-child transmission, with potentially serious long-term consequences for the child, but which can be effectively prevented with immune prophylaxis.

Healthy pregnant women are not usually more susceptible to infections than non-pregnant women, but when infections occur during pregnancy there is often considerable concern about the possible adverse effects on the fetus or newborn. Perinatal infections remain a major cause of morbidity and mortality in infants in both the developed and developing world, and the range of infections known to be associated with perinatal infections continues to increase. Diagnosis has improved with new diagnostic techniques, including advanced serological techniques and ultrasonography.

Doctors in obstetrics and paediatrics and their midwifery colleagues need to be aware of recent advances in knowledge with regard to these conditions, which can translate to preventive measures and which have implications for decisions regarding antenatal screening packages. Several exhaustive reference books exist; and this book is not intended to replace these. We hope that it will provide a concise up-to-date review of the field which will provide easily accessible information, with an explanation of the underlying mechanisms and approaches to prevention, for medical practitioners of all disciplines. The authors are all experts in their fields, drawn from both developed and developing countries, which we hope will add to the relevance of this book for all settings.