Summaryobjective To evaluate possible severe acute respiratory syndrome (SARS) infection associated risk factors in a SARS affected hospital in Beijing by means of a case control study.methods Fifty-one infected and 426 uninfected staff members were asked about risk behaviours and protective measures when attending to SARS patients. Univariate and multivariate logistic regression analyses were performed to identify the major risk and protective factors.

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. British Ecological Society is collaborating with JSTOR to digitize, preserve and extend access to Journal of Animal Ecology. SUMMARY(1) In this paper, the relation between the tendency to leave a patch and the experience in that patch is studied, from a functional point of view.(2) The study is based on empirical data rather than the usual a priori modelling. The relative effects of several factors on patch-leaving decisions are estimated from the data and it is tested which factors have significant effects. Afterwards, we discuss the implications of the effects that were found in a functional context.(3) This approach is an important extension to a priori modelling, since it can indicate the relative importance of several aspects of the natural environment in determining the foraging strategy.(4) Experiments were done with the parasitic wasp Leptopilina heterotoma. In the trials, wasps were deposited in a Petri dish containing a patch of yeast with Drosophila larvae. Their behaviour was continuously recorded until they left the patch for more than 60 s.(5) The data were analysed by means of the proportional hazards model (Cox 1972) for factors affecting the leaving tendency of the parasitoids, i.e. the chance per unit of time that the patch was left.(6) It was found that the leaving tendency decreases with the number of ovipositions.(7) Oviposition rates experienced in the patch also have a strong influence on the tendency of the wasps to leave. As expected, the most recently experienced oviposition rates have the strongest effect. Long foraging times between recent ovipositions produce a high leaving tendency.(8) The number of times the patch has been left before, during periods shorter than 60 s, also strongly influences the tendency to leave.(9) Rejection rates with parasitized hosts do not affect the leaving tendency significantly.(10) These findings suggest that the behaviour of the wasps is strongly adapted to a clumped distribution of hosts over patches.Information processing by foragers empirical data. The best known theorem about optimization of patch residence times is Charnov's (1976) marginal value theorem. This theorem is based on the assumptions that a forager maximizes average intake rate, knows all relevant environmental characteristics (i.e. inter-patch travel times and patch depletion rates) and is unconstrained. Of course, these assumptions are not met in practice. Therefore, many authors have sought to make them more realistic. In particular, the assumption of an omniscient forager has been dropped by, e.g. Iwasa, Higashi & Yamamura (1981), McNair (1982), McNamara & Houston (1987a) and Green (1987). All these authors derive optimal strategies for hypothetical...

Abstract. Variations in fecal Schistosoma japonicum egg counts were studied in ZhuXi administrative village, JiangXi Province, China. Population stool examinations were collected with duplicate, standard, 41.5-mg Kato-Katz thick smears on seven consecutive days for 570 individuals from two natural (individual) villages: village I with high endemicity and village II with low endemicity. The proportion of individuals with at least one positive count increased from 42.4% after a single measurement to 68.3% after seven measurements in village I (n ϭ 356), and from 17.0% to 36.0% in village II (n ϭ 214), respectively. This demonstrates a very high variation in repeated S. japonicum egg counts and a considerable lack of sensitivity of the Kato-Katz technique; light and moderate infections are especially missed with a single or a few measurements. The observed day-to-day variation in individual egg counts is highly aggregated (variance higher than the mean) and suggestive of a negative binomial distribution. For five individuals on three days, repeated sampling from different locations of a stool specimen shows a clear trend with egg counts decreasing from the beginning of the stool to the end and from the outside layer to the center. Ten multiple samples from a particular subsection (10-30 g) of a stool specimen for 44 positive individuals still showed aggregation in egg counts, particularly for high intensities of infection. This means that the aggregation in repeated daily S. japonicum egg counts cannot be explained alone by a specific day-to-day component and variation in the concentration of eggs at different locations in the stool. There also exists clustering of eggs within parts of the stool.Most control programs and epidemiologic studies on Schistosoma japonicum and S. mansoni infection are based on the detection of parasite eggs using the modified KatoKatz method. 1-4 Generally, levels of egg excretion are used as an index of the intensity of infection. Individual diagnosis of infection is commonly based on one stool examination. However, for S. mansoni it has been shown that a single stool examination considerably underestimates the prevalence; many light infections are especially missed. 5 Fecal egg counts as a quantitative measure of infection on S. mansoni in epidemiologic studies are the result of inter-and intraindividual variations: the former reflecting egg counts varying from individual to individual caused by differences in worm loads, and the latter reflecting egg count fluctuation for an individual with a given worm load from time to time and/or within a fecal specimen. [5][6][7][8][9] Based on a stochastic model that takes into account this inter-and intra-individual variation in egg counts, projections can be made of how many individuals are truly infected with S. mansoni in a population. 10 We expect similar mechanisms to exist for S. japonicum infection, but thus far detailed studies have not been undertaken. 11 Imperfect diagnosis of S. japonicum by routine stool examination has however been ...

Due to the COVID-19 pandemic, many key neglected tropical disease (NTD) activities have been postponed. This hindrance comes at a time when the NTDs are progressing towards their ambitious goals for 2030. Mathematical modelling on several NTDs, namely gambiense sleeping sickness, lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminthiases (STH), trachoma, and visceral leishmaniasis, shows that the impact of this disruption will vary across the diseases. Programs face a risk of resurgence, which will be fastest in high-transmission areas. Furthermore, of the mass drug administration diseases, schistosomiasis, STH, and trachoma are likely to encounter faster resurgence. The case-finding diseases (gambiense sleeping sickness and visceral leishmaniasis) are likely to have fewer cases being detected but may face an increasing underlying rate of new infections. However, once programs are able to resume, there are ways to mitigate the impact and accelerate progress towards the 2030 goals.

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Abstract. We determined the nutritional status of children less than five years of age in an area in rural western Kenya with intense malaria transmission, a high prevalence of severe anemia and human immunodeficiency virus, and high infant and under-five mortality (176/1,000 and 259/1,000). No information is available on the prevalence of malnutrition in this area. Three cross-sectional surveys were conducted between 1996 and 1998 to monitor the effect of insecticide-treated bed nets on child morbidity. Anthropometric indices are presented for 2,103 children collected prior to and during intervention (controls only). The prevalence of stunting (Z-scores for height-for-age [HAZ] <−2), wasting (Z-scores for weight-for-height [WHZ] <−2) and being underweight (Z-scores for weight-for-age [WAZ] <−2) was 30%, 4%, and 20%, respectively. This was severe (Z-score <−3) in 12% (stunting), 1% (wasting), and 5% (underweight) of the children. Few children less than three months of age were malnourished (<2%), but height-for-age and weight-forage deficits increased rapidly in children 3−18 months of age, and were greatest in children 18−23 months old (44% stunted and 34% underweight). While the mean HAZ and WAZ stabilized from 24 months of age onwards, they still remained substantially below the reference median with no evidence of catch-up growth. Malnutrition is likely to interact with infectious diseases, placing children 3−24 months of age at high risk of premature death in this area.

STDSIM is a dynamic stochastic simulation model for decision support in attempts to control sexually transmitted diseases (STDs). It describes the mechanisms responsible for the transmission of five STDs, including HIV/AIDS, at the level of individuals. A large variety of outcome measures (for example, STD prevalence, incidence, and mortality) can be calculated for different groups of the population (for example, adolescents, prostitutes, pregnant women, and migrants) to evaluate the effects of alternative STD control interventions. We designed the model to support decision making for different settings in developing countries, with Nairobi (Kenya) as its first application area. The model adequately describes STD prevalences and the time-trend of HIV prevalence measured in Nairobi. As an illustration of the possibilities of the model, we show model predictions of the effects of improved STD care and increased condom use on the prevalence and incidence of HIV.

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