Horizontal HIV transmission to children of HIV-uninfected mothers: A case series and review of the global literature.

Background: Vertical transmission is the predominant route for acquisition of HIV infection in children, either in utero, intrapartum or postnatally through breast feeding. Less frequently, children may acquire HIV by horizontal transmission. Horizontal transmission may be healthcare-associated (infusion of HIV-contaminated blood products, use of contaminated needles, syringes and medical equipment, or through ingestion of HIV in expressed breastmilk). Community-acquired HIV transmission to children may occur following surrogate breastfeeding, pre-mastication of food, and sexual abuse.

Methods: Children with suspected horizontally acquired HIV infection were identified by retrospective folder review of existing patients (2004-2014) and by prospective interview and examination of new patients (from 2009 onwards), at a hospital-based paediatric antiretroviral clinic in Cape Town, South Africa. The global literature on horizontal HIV transmission to children (1 January 1986-1 November 2019) was reviewed, to contextualize the local findings.

Results: Among the 32 children with horizontal HIV transmission (15 identified retrospectively and 17 prospectively), the median age at first diagnosis was 79 months (interquartile range 28.5-91.5); most children (90.6%) had advanced HIV disease at presentation. HIV transmission was considered healthcare-associated in 15 (46.9%), community-associated in ten (31.3%), possibly healthcare or community-associated in five (15.6 %); and unknown in two children (6.3%).

Conclusion: Horizontal HIV transmission to children is an important public health issue, with prevention efforts requiring intervention at healthcare facility- and community-level. Greater effort should be made to promptly identify and comprehensively investigate each horizontally HIV-infected child to establish possible routes of transmission and inform future prevention strategies.