Background In sub-Saharan Africa, large amounts of funding continue to be directed towards HIV-specific care and treatment, often with claims of ‘health system strengthening’ effect. Such claims rarely account for the impact on human relationships and decisions that are core to functional health systems. This research examined how establishment of externally funded HIV services influenced trusting relationships in Zambian health centres.

Methods An in-depth, multicase study included four health centres selected for urban, peri-urban and rural characteristics. Case data included healthcare worker (HCW) interviews (60); patient interviews (180); direct observation of facility operations (2 weeks/centre) and key informant interviews (14) which were recorded and transcribed verbatim. Thematic analysis adopted inductive and deductive coding guided by a framework incorporating concepts of workplace trust, patient–provider trust, intrinsic and extrinsic motivation.

Results HIV service scale-up impacted trust in positive and negative ways. Investment in HIV-specific infrastructure, supplies and quality assurance mechanisms strengthened workplace trust, HCW motivation and patient–provider trust in HIV departments in the short-term. In the health centres more broadly and over time, however, non-governmental organisation-led investment and support of HIV departments reinforced HCW's perceptions of the government as uninterested or unable to provide a quality work environment. Exacerbating existing perceptions of systemic workplace inequity and nepotism, uneven distribution of personal and professional opportunities related to HIV service establishment contributed to interdepartmental antagonism and reinforced workplace practices designed to protect individual HCW's interests.

Conclusions Findings illustrate long-term negative effects of the vertical HIV resourcing and support structures which failed to address and sometimes exacerbated HCW (dis)trust with their own government and supervisors. The short-term and long-term effects of weakened workplace trust on HCWs' motivation and performance signal the importance of understanding how such relationships play a role in generating virtuous or perverse cycles of actor interactions, with implications for service outcomes.