The present study aimed to determine the 3-month incidence of relapse and associated factors among children who recovered under the Optimising treatment for acute MAlnutrition (OptiMA) strategy, a MUAC-based protocol. A prospective cohort of children successfully treated for acute malnutrition was monitored between April 2017 and February 2018. Children were seen at home by community health workers (CHWs) every 2 weeks for 3 months. Relapse was defined as a child who had met OptiMA recovery criteria (MUAC ≥ 125 mm for two consecutive weeks) but subsequently had a MUAC < 125 mm at any home visit. Cumulative incidence and incidence rates per 100 child-months were estimated. Multivariable survival analysis was conducted using a shared frailty model with a random effect on health facilities to identify associated factors. Of the 640 children included, the overall 3-month cumulative incidence of relapse was 6⋅8 % (95 % CI 5⋅2, 8⋅8). Globally, the incidence rate of relapse was 2⋅5 (95 % CI 1⋅9, 3⋅3) per 100 child-months and 3⋅7 (95 % CI 1⋅9, 6⋅8) per 100 child-months among children admitted with a MUAC < 115 mm. Most (88⋅6 %) relapses were detected early when MUAC was between 120 and 124 mm. Relapse was positively associated with hospitalisation, with an adjusted hazard ratio (aHR) of 2⋅06 (95 % CI 1⋅01, 4⋅26) for children who had an inpatient stay at any point during treatment compared with children who did not. The incidence of relapse following recovery under OptiMA was relatively low in this context, but the lack of a standard relapse definition does not allow for comparison across settings Closer follow-up with caretakers whose children are admitted with MUAC < 115 mm or required hospitalisation during treatment should be considered in managing groups at high risk of relapse. Training caretakers to screen their children for relapse at home using MUAC could be more effective at detecting early relapse, and less costly, than home visits by CHWs.

Risk populations for HIV infections tend to neglect condom use, making alternative preventive approaches necessary. Accordingly, we modelled the risk of sexual HIV transmission for condom use vs. use of rapid diagnostic test (RDT) systems with subsequent exclusion of potential sexual partners with a correctly or falsely positive test from unprotected sex with and without the use of HIV pre-exposure prophylaxis (PrEP) in a bio-statistical approach. We combined a previously described model of transmission risk for HIV-exposed individuals with a newly suggested model of risk of HIV exposure for sexually active HIV-negative individuals. The model was adapted for several stages of infection and different strategies of HIV infection prevention.

HIV prevention with RDTs can reduce the transmission risk by up to 97% compared with having sex without any prevention and up to 80% compared with condom use. Nevertheless, RDT-based prevention strategies demonstrate a lack of protection in several stages of infection; in particular, RNA-based RDT systems may fail under treatment. RDT-based pre-screening of potential sex partners prior to unprotected sexual contacts substantially reduces HIV transmission risk. Combination of different prevention strategies is advisable for high-risk groups.

Light microscopy of stained blood films is still the mainstay of malaria diagnosis in many regions, but its pre-eminence is threatened by accurate and sensitive rapid diagnostic tests (RDTs) based on immunochromatography which are now widely used in the field. In well-resourced regions, nucleic acid detection easily out performs microscopy and RDTs. This paper reviews the main in vitro methods for parasite detection and considers future trends in diagnostics, both for sophisticated laboratory settings and for field use.