Background
In Nigeria and elsewhere, informal drug sellers, or patent and proprietary medicine vendors (PPMVs), are a common source of care for children with malaria, diarrhoea, and pneumonia. However, their knowledge and stocking of recommended treatments for these common childhood illnesses are not well understood.

Methods
A census of PPMV shops was conducted in Kogi and Kwara states. A shop survey was conducted on a subset of 250 shops. Multivariate regression analysis was used to assess associations between shop worker characteristics and (1) knowledge of optimal treatments for malaria, diarrhoea, and pneumonia, and (2) stocking of essential medicines to treat these illnesses.

Results
From the census, 89.9 % of shops stocked oral rehydration solution (ORS), while 61.1 % of shops stocked artemisinin-based combination therapies and 72.2 % of shops stocked amoxicillin. Stocking patterns varied by state, urban/rural location, and according to whether or not the shop was headed by someone with formal health training (e.g. having a professional health education degree). In multivariate analyses, selling drugs wholesale and participating in any training in the past year was associated with a higher likelihood of naming the correct treatment for malaria, and having formal health training was associated with stocking ORS. However, few other PPMV characteristics were predictive of correct knowledge of optimal treatments and stocking behaviour.

Conclusion
Many PPMVs lack the knowledge and tools to properly treat common childhood illnesses. PPMV knowledge and selling of essential medicines for these illnesses should be strengthened to improve child health in Nigeria.