Substantially reduced pre-patent parasite multiplication rates are associated with naturally acquired immunity to Plasmodium falciparum.

Naturally acquired immunity to Plasmodium falciparum's asexual blood stage reduces parasite multiplication at microscopically detectable densities. The effect of natural immunity on initial prepatent parasite multiplication during the period following a new infection has been uncertain, contributing to doubt regarding the utility of experimental challenge models for blood-stage vaccine trials. Here we present data revealing that parasite multiplication rates during the initial prepatent period in semi-immune Gambian adults are substantially lower than in malaria-naive participants. This supports the view that a blood-stage vaccine capable of emulating the disease-reducing effect of natural immunity could achieve a detectable effect during the prepatent period.

The difficult venous ulcer: case series of 177 ulcers referred for vascular surgical opinion following failure of conservative management.

Venous leg ulcers are common, chronic, debilitating, and expensive. Evidence supports use of compression bandaging, with superficial venous surgery in selected cases, but these interventions frequently fail to achieve healing. We describe a series of 152 consecutive referrals from a nurse-led specialist dermatology clinic to a vascular surgical service; a group posing particularly challenging problems. This observational study, with median follow-up of 18 months, describes outcomes in a number of important clinically identifiable subgroups. Its findings may assist service planning and discussion of the surgical role within multidisciplinary ulcer management.