Congenital HIV infection after failure of serological screening. Importance of implementing a second screening for HIV infection during the third trimester of pregnancy

HIV infection is still a severe childhood health problem in less developed countries.¹ Although the incidence of new infections has decreased in recent years, 160,000 new cases are still occurring on an annual basis.^1,2 In a setting such as ours, with easy accessibility to the healthcare system and to antiretroviral therapy (ART), the perinatal HIV transmission rate can be reduced to less than 1%.³ However, even today cases are still being reported, as demonstrated by the six new diagnoses due to mother-to-child transmission recorded in 2016 in Spain, of whom two were of Spanish origin and the rest from other countries, with no data on the prevention protocols applied in the latter (two from Sub-Saharan Africa, one from Latin America and another from Eastern Europe).⁴

Recently, in the latest consensus document from the Grupo de Estudio de Sida [AIDS study group (GeSIDA)] and the Sociedad Española de Ginecología y Obstetricia [Spanish Society of Gynaecology and Obstetrics, (SEGO)], the pregnancy screening protocol has been modified. It is now recommended to do an HIV serological measurement in the third trimester, in addition to the routine one in the first trimester. In high-risk cases, another measurement can also be added in the second trimester.⁵ However, the North American guidelines from the Centers for Disease Control and Prevention (CDC) only recommend repeating the test in the third trimester in pregnant women with a high risk of contracting HIV, defined as those who receive care in areas with a high incidence of HIV infection.⁶ The performance of this second measurement is considered cost-effective, given that the cost of ART far exceeds the cost in the measurement of a second test, which is currently around two dollars per measurement.^7,8

Not carrying out the second test in the third trimester may lead to errors in the diagnosis of infections acquired during pregnancy which may be passed on to the foetus. In our centre, we recently cared for a male newborn aged 27 days who was brought to the paediatric emergency department due to malnutrition and epistaxis which had started two days beforehand. He was also partly rejecting food, with no other symptoms. The pregnancy was monitored in the mother's local hospital. The first semester serological tests (HIV, syphilis, hepatitis B and C viruses), which were performed in the eighth week of pregnancy, were negative. The baby was delivered through a normal vaginal delivery with amniorrhexis of 46 h at week 38 + 4 of pregnancy. The newborn baby weighed 2775 g (15th percentile). He was admitted at 3 days old due to weight loss and symptomatic hypoglycaemia which were attributed to poor feeding technique by the parents. He was readmitted at 27-days-old with a clinical picture of malnutrition, weighing 2570 g (percentile <3) with a size of 50 cm (3rd percentile).

In the study of malnutrition causes in the infant which included, among others, screening for metabolic diseases, congenital heart diseases, blood diseases and congenital infections, a serological test and an HIV viral load measurement were ordered which were positive (RNA HIV-1 6,654,360 copies/ml). HIV-1 infection was also confirmed in both parents, which they were unaware of until that time.

The risk of primary HIV infection is greater during pregnancy due to the fact that, as a result of hormonal changes which occur during pregnancy, there are alterations in the vaginal mucosa and in the immune system, which promote the acquisition of the virus.⁹ Furthermore, in these cases, the risk of perinatal transmission increases up to eight times, hence the importance of obligatory compliance with the third trimester screening programmes in all pregnant women.¹⁰

With this letter, we want to warn of the risk of failure with the first-semester prenatal screening programme, and report a new case of mother-to-child transmission of HIV in our setting, which also displayed an atypical presentation. This case, along with others published in the literature,¹⁰ would potentially be preventable if the recommendation for a second serological test in the third trimester was compulsory and was not performed on an optional basis, as it has been up to now.