The loss of a child is a traumatising experience for the parents, who go through devastating emotional pain, at times undergoing the grieving process for years. The death of a newborn or stillbirth may occur as a result of congenital infections, which are acquired during pregnancy (in utero), at and around the time of delivery (perinatal), or after delivery (postnatal).⁽²⁾ Every year, congenital infections contribute to a considerable number of deaths in low- and middle-income countries. However, these tragedies could be prevented through simple, cost-effective interventions, such as educating expectant mothers as well as the broader community, systematic screening of expectant mothers and immunisation.⁽³⁾

This paper reviews recent reports on the prevalence and extent of congenital infections in Africa, as well as measures that could feasibly be taken to control them. In addition, reasons as to why these infections are still a public health concern on the African continent are discussed.

Congenital infections: Definition and infectious agents

Congenital infections are a variety of diseases with a common mode of transmission: vertical transmission or mother-to-child transmission (MTCT). A foetus or embryo is infected by its mother through two routes:

• Ascending infection from the upper vagina via the uterine cervix to the amniotic fluid; or
• Haematogenous spread (transplacental infection) as a result of maternal viremia, bacteraemia or parasitemia.⁽⁴⁾

Presented in Table 1 are some of the common infectious agents responsible for congenital infections

Table 1: Infectious agents responsible for congenital infections

This review will focus on congenital syphilis (CS) caused by Treponema pallidum, MTCT of HIV, congenital toxoplasmosis caused by Toxoplasma gondii and congenital rubella syndrome (CRS) caused by the rubella virus, because of their contribution to the high burden of disease in African countries and, paradoxically, the availability of simple and cost-effective measures to prevent them.

Congenital syphilis

The infection of the foetus by Treponema pallidum causes CS, a condition which occurs with high frequency in pregnant women with untreated early syphilis infection. CS frequently causes abortion or stillbirth and, in other cases, may cause infant death through pre-term delivery of low birth-weight infants, or from generalised systemic disease.⁽⁵⁾ Estimates from the World Health Organisation (WHO) show that, each year, maternal syphilis is responsible for 460,000 abortions or stillbirths, 270,000 cases of CS and the birth of 270,000 low birth-weight or premature babies worldwide.⁽⁶⁾ High rates of syphilis sero-positivity have consistently been reported at antenatal care (ANC) clinics in Africa, where CS may account for about 1% of admissions at paediatric wards.⁽⁷⁾ In Ethiopia, it was estimated that 5% of all foetuses each year were lost through syphilis-induced abortion; while in Zambia 24% of stillbirths and 30% of perinatal mortality were attributed to CS.⁽⁸⁾ Furthermore, reported case-fatality rates for symptomatic CS on the African continent vary between 15% in Mozambique to 38% in South Africa.⁽⁹⁾ Despite being the leading cause of neonatal infections, ahead of HIV and tetanus, CS is not a public health priority in most countries.⁽¹⁰⁾

Hawkes has earmarked the prevention of CS as a venture that is likely to be successful as it meets three important criteria.⁽¹¹⁾ Firstly, CS is a widespread and burdensome problem, as shown above. Secondly, the health policy environment for CS is promising, given the fact that over three quarters of Ministries of Health in 22 Sub-Saharan African countries have national policies for syphilis screening during pregnancy.⁽¹²⁾ Finally, the screening of all pregnant women and treatment of those who are infected is cost-effective in most countries, largely because of the low-cost screening tests and the inexpensive penicillin treatment.⁽¹³⁾ In spite of all these, the incidence of CS remains unacceptably high in many countries; in fact, the number of recorded cases has recently risen in some countries.⁽¹⁴⁾

Several studies have been conducted to explore reasons as to why CS is still so prevalent in Africa. Among the issues identified were the failure of basic systems of ANC and the failure by healthcare systems to control sexually transmitted infections (STIs). The lack of adequate ANC with mothers having late, few or no antenatal visits, the absence of systematic screening during antenatal visits in some countries, and the inadequate treatment of syphilis have all been cited as contributing factors.⁽¹⁵⁾

In spite of the above, the WHO has launched a global initiative to eliminate congenital syphilis, with several regions having made substantial progress towards elimination.⁽¹⁶⁾ Specifically, the WHO is aiming at the prevention of MTCT of syphilis through early ANC for all women, the treatment of all sexual partners of infected women, and prophylactic treatment of all neonates born to sero-positive mothers with a single dose of penicillin.⁽¹⁷⁾ In order to make efforts aimed at eliminating CS more effective, some authors have suggested the alignment of CS prevention programmes with programmes to prevent MTCT of HIV.⁽¹⁸⁾

Congenital toxoplasmosis

Primary toxoplasmosis infection of the mother during pregnancy may cause spontaneous abortion of the foetus or stillbirth. A newborn exposed to Toxoplasma gondii in utero may develop congenital toxoplasmosis resulting in major ocular and neurological consequences.⁽¹⁹⁾

A review was conducted in 2009 to evaluate available epidemiological data on the sero-prevalence of Toxoplasma gondii worldwide, with a particular focus on pregnant women or women of child-bearing age (15-45 years).⁽²⁰⁾ At the time, prevalence rates were 57.9% in Egypt, 58.4% in Tunisia, 21% in Mali and 20.8% in Nigeria, where the risk factors for sero-positivity were the consumption of rodents and contact with soil.⁽²¹⁾ The authors subsequently recommended surveillance with a simple blood test early in pregnancy for non-immune women living in high-prevalence settings.⁽²²⁾ It is also important to educate pregnant women regarding preventive measures that can be taken to control congenital toxoplasmosis; these measures include avoiding raw or undercooked meat and contact with cats.

HIV infection

MTCT during pregnancy, childbirth, or breastfeeding is the dominant mode of HIV acquisition among children worldwide. Globally, an estimated 430,000 children were infected with HIV in 2008, with more than 1,000 new infections among children each day, the majority of which occur are in Sub-Saharan Africa.⁽²³⁾ Currently, almost 90% of the world's two million HIV-positive children reside in Africa.⁽²⁴⁾ Prevention of MTCT (PMTCT) should therefore be a public health priority in the region.

Perinatal infection is currently a rare occurrence in high-income countries where PMTCT services are widely available.⁽²⁵⁾ The following measures contributed to the reduction in the risk of infection among infants during pregnancy and delivery in high-income countries: early identification of HIV infection in pregnant women through routine, opt-out antenatal HIV testing, immediate assessment of the treatment needs of HIV-infected pregnant women, and the provision of antiretroviral treatment (ART) when needed or antiretroviral (ARV) prophylaxis if therapy is not yet required.⁽²⁶⁾ However, MTCT of HIV remains high in Sub-Saharan Africa due to several factors, namely: the limited availability of family planning and ANC services as well access to these; low rates of HIV testing among pregnant women; and the fact that ART services and CD4 cell count testing do not form part of antenatal services; compounded by human resource constraints and a lack of political will to prioritise maternal health and PMTCT.⁽²⁷⁾ Only 21% of women who became pregnant in low- and middle-income countries in 2008 were tested for HIV.⁽²⁸⁾ These statistics point to a need to improve HIV testing rates in these countries.

The issue of children breastfed by HIV infected mothers is not negligible. In countries where breastfeeding is common, the probability of MTCT without any ARV drugs administered to the HIV-infected mother or the HIV-exposed child during the breastfeeding period is approximately 20-45%.⁽²⁹⁾ The only viable method for eliminating HIV transmission as a result of breastfeeding is to completely avoid breastfeeding. However, this alternative is rather impossible in African countries due to the costs associated with replacement foods meant to meet the nutritional needs of the infant in the absence of breast milk, the unsafe water supply and the stigma associated with not breastfeeding.⁽³⁰⁾ To reduce the risk of transmission during breastfeeding, the Guidelines on HIV and Infant Feeding 2010 recommend exclusive breastfeeding for the first six months of life, and continued breastfeeding and complementary foods from months 6 to 12, when either the mother or the baby is receiving ARVs.⁽³¹⁾

Below are aspects of the WHO's strategic approach for preventing paediatric HIV infection:

• Prevention of HIV infection among young persons and pregnant women;
• Prevention of unintended pregnancies in HIV-infected women. It is estimated that access to family planning services by all women in Sub-Saharan Africa could prevent as many as 160,000 new paediatric HIV infections per year;
• PMTCT;
• and provision of treatment, care, and support to HIV-infected women and their families.⁽³²⁾

Congenital rubella syndrome

Rubella, commonly known as German measles, is a viral infection responsible for a generally mild ailment among adults. However, rubella represents a public health concern because of its effects on the foetus if the mother is infected in the early months of pregnancy. CRS occurs when the virus is transmitted to the foetus by its mother, resulting in foetal death or the delivery of an infant with serious congenital birth defects. The risk of CRS in the first 8 to 10 weeks of pregnancy is up to 90%, after which the risk of infection of the foetus is less probable, and virtually non-existent after 16 weeks.⁽³³⁾ CRS is a major cause of blindness, deafness, congenital heart disease and mental retardation.⁽³⁴⁾ Globally, it is estimated that 100 000 cases of CRS occur every year.⁽³⁵⁾ These figures are probably an underestimation due to under-reporting and the difficulties associated with accurately diagnosing CRS.⁽³⁶⁾

In countries where vaccination against rubella is part of the national immunisation system, the incidence of rubella and CRS has been dramatically reduced.⁽³⁷⁾ However, only a few African countries have introduced rubella vaccines in their national immunisation programmes, despite the vaccine being widely available in the private sector. The WHO recommends the introduction of a rubella vaccine only if vaccine coverage greater than 80% can be sustained on a long-term basis. Rubella vaccines are presented either as a monovalent or associated with measles (MR), or measles and mumps (MMR).⁽³⁸⁾ Furthermore, vaccination programmes targeting pre-pubertal and adolescent girls must be implemented along with routine immunisation of all children. Finally, routine immunisation services and rubella surveillance systems must be strengthened.⁽³⁹⁾

Concluding remarks

Congenital infections remain a major public health problem in Africa, despite the availability of simple, cost-effective and feasible interventions. The implementation of basic strategies, such as education, universal screening and immunisation, would help reduce the risk of MTCT in many African countries.

Written by Patrick Ngassa Piotie ⁽¹⁾

NOTES:

(1) Contact Patrick Ngassa Piotie through Consultancy Africa Intelligence's Public Health Unit ( public.health@consultancyafrica.com). This CAI discussion paper was developed with the assistance of Tsholofelo Thomas and was edited by Liezl Stretton.
(2) 'Transmitted by the mother to her infant', Latin American Center for Perinatology / Women and Reproductive Health – Pan American Health Organisation / World Health Organisation, CLAP scientific publication 1567.02, 2008.
(3) Ibid.
(4) Ibid.
(5) Ndowa, F. and Peterman, T., 2008. "Syphilis", in Heymann, D.L. (ed.). Control of communicable diseases manual (19th edition). American Public Health Association: Washington, D.C.
(6) Finelli, L., et al., 1998. Congenital syphilis. Bulletin of the World Health Organisation, 76(Suppl. 2), pp. 126-128.
(7) Saloojee, H., et al., 2004. The prevention and management of congenital syphilis: An overview and recommendations. Bulletin of the World Health Organisation, 82(6), pp. 424-430.
(8) Ibid.
(9) Ibid.
(10) Ibid.
(11) Hawkes, S., 2009. Eliminating congenital syphilis-if not now then when? Sexually Transmitted Diseases, 36(11), pp. 721-723.
(12) Gloyd, S., Chai, S. and Mercer, M.A., 2001. Antenatal syphilis in Sub-Saharan Africa: Missed opportunities for mortality reduction. Health Policy Plan, 16(1), pp. 29-34.
(13) Hawkes, S., 2009. Eliminating congenital syphilis-if not now then when? Sexually Transmitted Diseases, 36(11), pp. 721-723.
(14) Ibid.
(15) Saloojee, H., et al., 2004. The prevention and management of congenital syphilis: An overview and recommendations. Bulletin of the World Health Organisation, 82(6), pp. 424-430.
(16) Hawkes, S., 2009. Eliminating congenital syphilis-if not now then when? Sexually Transmitted Diseases, 36(11), pp. 721-723.
(17) Schmid, G.P., et al., 2007. The need and plan for global elimination of congenital syphilis. Sexually Transmitted Diseases, 34 Suppl, pp. S5-S9.
(18) Mullick, S., et al., 2004. Controlling congenital syphilis in the era of HIV/AIDS. Bulletin of the World Health Organisation, 82(6), pp. 431-432; Klausner, J.D., 2007. Introduction to special issue on congenital syphilis elimination. Sexually Transmitted Diseases, 34 Suppl, pp. S1.
(19) Pappas, G., Roussos, N. and Falagas, M.E., 2009. Toxoplasmosis snapshots: Global status of Toxoplasma gondii and implications for pregnancy and congenital toxoplasmosis. International Journal for Parasitology, 39(12), pp. 1385-1394.
(20) Ibid.
(21) Ibid.
(22) Ibid.
(23) Mofenson, L.M., 2010. Prevention in neglected subpopulations: Prevention of mother-to-child transmission of HIV infection. Clinical Infectious Diseases, 50(S3), pp. S130–S148; '2008 report on the global AIDS epidemic', Joint United Nations Programme on HIV/AIDS, August 2008, http://www.unaids.org.
(24) '2008 report on the global AIDS epidemic', Joint United Nations Programme on HIV/AIDS, August 2008, http://www.unaids.org.
(25) Buchanan, A.M. and Cunningham, C.K., 2009. Advances and failures in preventing perinatal human immunodeficiency virus infection. Clinical Microbiology Reviews, 22(3), pp. 493-507.
(26) Mofenson, L.M., 2010. Prevention in neglected subpopulations: Prevention of mother-to-child transmission of HIV infection. Clinical Infectious Diseases, 50(S3), pp. S130–S148.
(27) Ibid.
(28) Ibid.
(29) Mahy, M., et al., 2010. What will it take to achieve virtual elimination of mother-to-child transmission of HIV? An assessment of current progress and future needs. Sexually Transmitted Infections, 86(Suppl. 2), pp. ii48-ii55.
(30) Mofenson, L.M., 2010. Prevention in neglected subpopulations: Prevention of mother-to-child transmission of HIV infection. Clinical Infectious Diseases, 50(S3), pp. S130-S148.
(31) Mahy, M., et al., 2010. What will it take to achieve virtual elimination of mother-to-child transmission of HIV? An assessment of current progress and future needs. Sexually Transmitted Infections, 86(Suppl. 2), pp. ii48-ii55.
(32) Mofenson, L.M., 2010. Prevention in neglected subpopulations: Prevention of mother-to-child transmission of HIV infection. Clinical Infectious Diseases, 50(S3), pp. S130–S148.
(33) Schoub, B.D., et al., 2009. Rubella in South Africa: An impending Greek tragedy? South African Medical Journal, 99(7), pp. 515-519.
(34) Robertson, S.E., et al., 2003. Rubella and congenital rubella syndrome: Global update. Pan American Journal of Public Health, 14(5), pp. 306-315.
(35) 'Rubella vaccines: WHO position paper', World Health Organisation Weekly Epidemiological Record 75, No. 20, 2000, pp. 161-169.
(36) Schoub, B.D., et al., 2009. Rubella in South Africa: An impending Greek tragedy? South African Medical Journal, 99(7), pp. 515-519.
(37) Ibid.
(38) Robertson, S.E., et al., 2003. Rubella and congenital rubella syndrome: Global update. American Journal of Public Health, 14(5), pp. 306-315, 'Rubella vaccines: WHO position paper', World Health Organisation Weekly Epidemiological Record 75, No. 20, 2000, pp. 161-169; Schoub, B.D., et al., 2009. Rubella in South Africa: An impending Greek tragedy? South African Medical Journal, 99(7), pp. 515-519; Robinson, J.L., et al., 2006. Prevention of congenital rubella syndrome - What makes sense in 2006? Epidemiologic Reviews, 28, pp. 81-87.
(39) Ibid.