As one article in a four-part PLoS Medicine series on water and sanitation, David Trouba and colleagues discuss the importance of improved sanitation to health and the role that the health sector can play in its advocacy.

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This review provides some evidence that interventions to improve excreta disposal are effective in preventing diarrhoeal disease. However, this conclusion is based primarily on the consistency of the evidence of beneficial effects. The quality of the evidence is generally poor and does not allow for quantification of any such effect. The wide range of estimates of the effects of the intervention may be due to clinical and methodological heterogeneity among the studies, as well as to other important differences, including exposure levels, types of interventions, and different degrees of observer and respondent bias. Rigorous studies in multiple settings are needed to clarify the potential effectiveness of excreta disposal on diarrhoea.

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Each year more than 2 million children die from diarrhoeal diseases; the same number again die from acute respiratory infections. The simple hygiene behaviour of washing hands with soap represents an effective way of preventing the transmission of many of these infections. However, rates of handwashing across the globe are low, presenting a challenge for health promotion programmes. Behaviour change is not easy, and past efforts based upon health education have met with limited success. New approaches are needed. We propose that much can be learnt from the world of consumer marketing. Rather than base communications programmes for behaviour change on increasing knowledge, marketers aim to respond to the inner desires and motivations of their target audiences. This study used consumer research to investigate the factors motivating handwashing with soap in order to inform a national communications campaign for Ghana. It revealed that the strongest motivators for handwashing with soap were related to nurturance, social acceptance and disgust of faeces and latrines, especially their smell. Protection from disease is mentioned as a driving force, but was not a key motivator of handwashing behaviour. The ways in which these findings have been translated into a handwash promotion campaign are discussed.

Epidemiological and biological studies provide compelling evidence for the protective effect of male circumcision against the acquisition of HIV. Three randomized controlled trials are currently underway to assess the impact of male circumcision as an HIV intervention in traditionally non-circumcising areas with high levels of heterosexually-transmitted infection. This study explores the acceptability of male circumcision among the rural Zulu around Hlabisa and Mtubatuba, KwaZulu-Natal, South Africa. A cross-sectional convenience sample of 100 men and 44 women was surveyed, and two male focus groups held, to ascertain circumcision preferences within the population. Four in-depth interviews with service providers assessed the feasibility of promoting male circumcision. Fifty-one per cent of uncircumcised men and 68% of women favoured male circumcision of themselves or their partners; while 50% of men and 73% of women would circumcise their sons. For men, the main predictors of circumcision preference pertained to beliefs surrounding sexual pain and pleasure; for women, knowledge about the relationship between male circumcision status and STI acquisition was the key indicator for circumcision preference. Among both sexes the main barrier to circumcision was fear of pain and death. The greatest logistical barrier was that circumcision can presently only be carried out by trained hospital doctors.

The foraging habitats of 7 species of marine apex predators were observed simultaneously in a shallow sea, with continuous measurements taken of the detailed bio-physical water column characteristics to determine habitat preferences. We found the occurrence of small-scale 'hotspots', where 50% of all animals were actively foraging in less than 5% of the 1000 km of transects surveyed. By investigating a contrasting range of foraging strategies across a variety of fisheating seabirds and marine mammals, we determined which habitat characteristics were consistently important across species. A static habitat variable, tidal stratification, log 10 (h/U 3 ) (h = water depth, U = tidal current amplitude), was found to be the best indicator of the probability of presence and abundance of individual species. All 7 mobile top-predators preferentially foraged within habitats with small-scale (2 to 10 km) patches having (1) high concentrations of chlorophyll in the sub-surface chlorophyll maximum (CHL max ) and (2) high variance in bottom topography, with different species preferring to forage in different locations within these habitats. Patchiness of CHL max was not associated with the locations of strong horizontal temperature gradients (fronts) or high surface chlorophyll values, but instead may be related to areas of high sub-surface primary production due to locally increased vertical mixing. These small-scale areas represent a newly identified class of spatially important location that may play a critical role within the trophic coupling of shallow seas. Such subsurface hotspots may represent the limited locations where the majority of predator-prey interactions occur, despite making up only a small percentage of the marine environment.KEY WORDS: Biological hotspots · Foraging habitats · Marine top predators · Predator-prey interactions · Shallow sea · Sub-surface chlorophyll maximum · Tidal mixing · Topography 408: 207-226, 2010 Review studies on the upwelling systems of the Pacific Ocean identified spatially and temporally predictable 'biological hotspots' with distinct surface signatures (Spear et al. 2001, Bakun 2006, Ballance et al. 2006, Sydeman et al. 2006. At this large scale, the mechanistic evidence behind the creation of hotspots for marine predator foraging points directly to both topographical features (Genin 2004, Yen et al. 2004 and primary productivity (Ware & Thomson 2005, Bost et al. 2009). The general conclusion of many largescale studies is that seabirds and marine mammals are found preferentially foraging within different types of frontal region: areas of intersection between different water mass types where there are steep surface (horizontal) gradients in water density. Biological reasoning links foraging to frontal locations via the elevated levels of primary production and aggregation of planktonic organisms found at fronts (Pingree et al. 1975, Franks & Chen 1996, Durazo et al. 1998, Russell et al. 1999, Lough and Manning 2001. However, some of the studies mentioned above stress...