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Background. South African (SA) children from disadvantaged communities are plagued by a double burden of under- and over-nutrition. The resulting overweight and obesity on the one hand, and stunting on the other, are risk factors for chronic diseases in adulthood. Objective. To determine the effect of school-based interventions on body composition of grade-4 children from lower socioeconomic communities in the Gqeberha region, SA. Methods. A cluster-randomised controlled trial was carried out with children from 8 schools. Schools were randomly assigned, either to a 10-week school-based intervention (4 schools) or a control condition (4 schools). The intervention comprised several arms, with each intervention school receiving a different combination of the following measures: physical activity, health and hygiene education, and nutrition education with supplementation. Effects on children’s body composition were evaluated using standardised, quality-controlled methods. Height and weight were assessed to calculate body mass index (BMI), and percentage body fat was measured via thickness of skinfolds (triceps and subscapular). Results. Overall, 898 children (458 boys and 440 girls) aged 8 - 11 years participated in the trial. Children’s BMI, BMI-for-age and percentage body fat increased significantly over time. Increases were similar in boys and girls. Body fat remained unchanged in underweight children, whereas increases occurred in normal weight and (particularly) overweight/obese peers. In normal-weight children, the physical activity intervention (either alone or combined with health education) mitigated increments in body fat levels. A similar pattern was observed in overweight/obese children, but only in the physical activity intervention cohort alone. Conclusion. Our study shows that normal-weight children are at risk of becoming overweight and children who are already overweight/ obese are at even greater risk of gaining weight. The physical activity intervention (alone or in combination with health education) can mitigate increases in body fat in normal-weight children as well as in overweight/obese children. Our findings reveal that school-based physical activity, nutrition and health and hygiene interventions can have beneficial effects on children’s body composition. Further analyses are needed to examine how (school-based) physical activity interventions should be designed to improve children’s health in lower socioeconomic areas.

O autor abre o artigo, situando a família na atual conjuntura, onde o modelo familiar passou por uma significativa mudança de paradigma, ou seja, do modelo estável de valores ao modelo instável. Em seguida, tece alguns acenos históricos sobre a obrigatoriedade do matrimônio na Igreja, contrastando o matrimônio ideal com as uniões irregulares em significativo aumento no seio da Igreja. Neste contexto, o autor enfoca o batismo de crianças, cujos pais vivem de modo irregular na Igreja, e a relação entre pastoral dos divorciados recasados e participação eucarística. Releva a experiência das Igrejas Ortodoxas e das Igrejas da Reforma para, em seguida, apresentar as soluções pautadas pela Igreja Católica. Conclui o artigo, usando o exemplo do bom samaritano para demonstrar o olhar condescendente que a Igreja Católica deveria ter diante dos matrimônios falidos na Igreja.Abstract: The Author begins the article by placing the family in its present context, where the family model has been subjected to a significant change of paradigm, going from a stable to an unstable model of values. Next, he discusses some of the historical background for the fact that the matrimony is obligatory in the Church, contrasting this ideal matrimony to the “irregular unions” that are increasing significantly inside the Church. In this context, the Author focuses on the baptism of children whose parents live in an irregular situation in terms of the Church, and the relationship between the spiritual care of remarried divorcees and Eucharistic participation. He reveals the experience of the Orthodox and Reform Churches in order to compare them to the solutions proposed by the Catholic Church. He concludes the article using the Good Samaritan’s example to demonstrate the type of tolerance that the Catholic Church should show towards broken marriages in the Church.

Reaktive Trennwandkolonnen bieten eine Moglichkeit, die Vorzuge der Trennwandkolonnen und der Reaktivrektifikation in einem Apparat zu kombinieren. Aufgrund der Neuartigkeit dieses komplexen Verfahrens sind ausgiebige, numerische Untersuchungen unabdingbar. Zu diesem Zweck wurde ein auf dem rigorosen Stoffaustauschmodell basiertes Simulationstool entwickelt. Die erfolgreiche Validierung des Modells und des Simulationstools anhand von Experimenten wird vorgestellt. The reactive dividing wall column concept provides an opportunity to combine the advantages of dividing wall columns and reactive distillation in one single unit. Due to the novelty of this complex process, extensive numerical investigations are necessary. For this purpose, a simulation tool has been developed, which applies the rigorous rate-based modelling approach. The successful validation of both the model and simulation tool are presented.

At the end of March 2006, the Czech Republic (CZ) witnessed a fast thawing of an unusually thick snow cover in conjunction with massive rainfall. Most watercourses suffered floods, and more than 90 shallow landslides occurred in the Moravian region of Eastern CZ, primarily in non-forested areas. This region, geologically part of the Outer Western Carpathians, is prone to landslides because the bedrock is highly erodible Mesozoic and Tertiary flysch. The available meteorological data (depth of snow, water equivalent of the snow, cumulative rainfall, air and soil temperatures) from five local weather stations were used to construct indices quantitatively describing the snow thaw. Among these, the Total Cumulative Precipitation (TCP) combines the amount of water from both thawing snow and rainfall. This concurrence of rain and runoff from snow melt was the decisive factor in triggering the landslides in the spring. The TCP index was applied to data of snow thaw periods for the last 20 years, when no landslides were recorded. This was to establish the safe threshold of TCP without landslides. The calculated safe threshold value for the region is ca. 100 mm of water delivered to the soil during the spring thaw (corresponding to ca. 11 mm day− 1). In 2006, 10% of the landslides occurred under or at 100 mm of TCP. The upper value of 155 mm covered all of the landslides.

In this work, (reactive) stripping carried out in film flow monolith reactors developed for counter-current operation is investigated. Usually mass transfer in reactive separation has to be determined experimentally due to the complex flow patterns. However, monoliths have a simple geometry; only laminar flow is present throughout the column. This allows the calculation of the thickness of the liquid layer directly using Navier–Stokes equations. With this thickness known, the mass transfer can be calculated based on the convection in axial direction, diffusion in radial direction and vapour–liquid equilibrium. A model has been developed and implemented in Fortran® based on the concept of a direct solution of convective diffusion equations, using the Thomas algorithm for solving the counter-current operation mode. Experimental data from literature have been used to validate the model for a binary and a multi-component system. The stripping of oxygen from saturated water by nitrogen was modelled assuming Fickian diffusion and vapour–liquid transfer based on the Henry constants. In a second step, multi-component diffusion and complex mass transfer at the interface were taken into account to describe the stripping of water by nitrogen from a mixture of hexyl-octanoate and cumene (solvent) under reactive stripping conditions.

A rigorous rate-based model for reactive sour gas absorption by aqueous amine solutions is presented which governs both the coupling of mass transfer and reaction and specific features of electrolyte species. The acceleration of mass transfer due to reactions in the liquid phase is taken into account rigorously, without application of enhancement factors. The model is implemented into the simulation environment Aspen Custom Modeler and validated by comparison of published pilot plant data with the simulation results. It is shown, that the model possesses a good predictivity for pilot plant scale as well as for industrial scale applications. In addition, the influence of reaction kinetics on the absorber performance is studied.

There is evidence that faecal egg counts ofSchistosoma mansonivary considerably from day to day, which results in poor sensitivity of single stool readings. Intra-specimen variation ofS. mansoniegg counts may also be considerable, but has previously been considered as the less important component. We quantified the relative contribution of these two sources of variation among 96 schoolchildren from an area in Côte d'Ivoire highly endemic forS. mansoni. Stool specimens were collected over 5 consecutive days, and 5 egg-counts were made in each specimen by the Kato–Katz technique. The point prevalence of the first sample was 42.7% and the cumulative prevalence after the maximum sampling effort was 88.5%. Using generalized linear mixed models we found that the presence ofS. mansonieggs in a stool sample varied much more between days than within specimens, indicating that stool sample examination over multiple days is required for accurate prevalence estimates. However, using the same approach, we found that among infected children intra-specimen variation in egg counts was 4.3 times higher than day-to-day variation. After praziquantel administration, day-to-day variation was more important than before, since most infections were very light and thus likely to be missed altogether by stool examination on a single day. We conclude that diagnostic sensitivity in high transmission areas is maximized by making several stool readings on several days, but examining 1 stool specimen several times can make reasonable estimates of infection intensity.

This chapter describes a system of fuzzy methods designed to solve a broad range of problems in multiple-criteria evaluation, and also their software implementation, FuzzME. A feature common to all the presented methods is the type of evaluation, well suited to the paradigm of fuzzy set theory. All evaluations take on the form of fuzzy numbers, expressing the extent to which goals of evaluation are fulfilled. The system of fuzzy methods is conceived to allow for different types of interaction among criteria of evaluation. Under no interaction, the fuzzy weighted average, fuzzy OWA operator, or WOWA operator are used to aggregate partial evaluations (depending on the evaluator’s requirements regarding type of evaluation). If interactions appear as redundancy or complementarity, the fuzzified discrete Choquet integral is the appropriate aggregation operator. Under more complex interactions, the aggregation function is defined through an expertly set base of fuzzy rules.

Background. Antimalarial use is a key factor driving drug resistance and reduced treatment effectiveness in Plasmodium falciparum malaria, but there are few formal, quantitative analyses of this process. Methods. We analyzed drug usage, drug failure rates, and the frequencies of mutations and haplotypes known to be associated with drug resistance over a 12-year period (1991–2002) in a site in Papua New Guinea. This period included 2 successive treatment policies: amodiaquine (AQ) or chloroquine (CQ) from 1991 through 2000 and their subsequent replacement by sulfadoxine-pyrimethamine (SP) plus AQ or SP plus CQ. Results. Drug use approximated 1 treatment per person-year and was associated with increasing frequencies of pfcrt and pfmdr1 mutations and of treatment failure. The frequency of pfdhfr mutations also increased, especially after the change in treatment policy. Treatment failure rates multiplied by 3.5 between 1996 and 2000 but then decreased dramatically after treatment policy change. Conclusions. With high levels of resistance to CQ, AQ, and SP, the deployment of the combination of both drugs appears to increase clinical effectiveness but does not decelerate growth of resistance. Our estimates of mutation and haplotype frequencies provide estimates of selection coefficients acting in this environment, which are key parameters for understanding the dynamics of resistance.

Background In areas where malaria endemicity is high, many people harbour blood stage parasites without acute febrile illness, complicating the estimation of disease burden from infection data. For Plasmodium falciparum the density of parasitaemia that can be tolerated is low in the youngest children, but reaches a maximum in the age groups at highest risk of infection. There is little data on the age dependence of tolerance in other species of human malaria. Methods Parasite densities measured in 24,386 presumptive malaria cases at two local health centres in the Wosera area of Papua New Guinea were compared with the distributions of parasite densities recorded in community surveys in the same area. We then analyse the proportions of cases attributable to each of Plasmodium falciparum, P. vivax, and P. malariae as functions of parasite density and age using a latent class model. These attributable fractions are then used to compute the incidence of attributable disease. Results Overall 33.3%, 6.1%, and 0.1% of the presumptive cases were attributable to P. falciparum, P. vivax, and P. malariae respectively. The incidence of attributable disease and parasite density broadly follow similar age patterns. The logarithm of the incidence of acute illness is approximately proportion to the logarithm of the parasite density for all three malaria species, with little age variation in the relationship for P. vivax or P. malariae. P. falciparum shows more age variation in disease incidence at given levels of parasitaemia than the other species. Conclusion The similarities between Plasmodium species in the relationships between parasite density and risk of attributable disease are compatible with the hypothesis that pan-specific mechanisms may regulate tolerance to different human Plasmodia. A straightforward mathematical expression might be used to project disease burden from parasite density distributions assessed in community-based parasitological surveys.

This article evaluates, by means of multivariate regression, critical factors influencing the collisions of motor vehicles with adult (over 17 years) cyclists that result in fatal injury of cyclists. The analysis is based on the database of the Traffic Police of Czech Republic from the time period 1995-2007. The results suggest that the most consequential categories of factors under study are: inappropriate driving speed of automobile; the head-on crash; and night-time traffic in places without streetlights. The cyclists' faults are of most serious consequence on crossroads when cyclists deny the right of way. Males are more likely to suffer a fatal injury due to a collision with a car than females. The most vulnerable age group are cyclists above 65 years. A fatal injury of a cyclist is more often driver's fault than cyclist's (598 vs. 370). In order to reduce the fatal risk, it is recommended to separate the road traffic of motor vehicles from bicyclists in critical road-sections; or, at least, to reduce speed limits there.

Background. Molecular markers for sulfadoxine-pyrimethamine (SP) resistance in Plasmodium vivax have been reported. However, data on the molecular correlates involved in the development of resistance to 4-aminoquinolines and their association with the in vivo treatment response are scarce. Methods. We assessed pvdhfr (F57L/I, S58R, T61M, S117T/N, and I173F/L) and pvmdrl (Y976F and F1076L) mutations in 94 patients who received amodiaquine (AQ) plus SP in Papua New Guinea (PNG). We then investigated the association between parasite genotype and treatment response. Results. The treatment failure (TF) rate reached 13%. Polymorphisms in pvdhfr F57L, S58R, T61M, and S117T/N and in pvmdrl Y976F were detected in 60%, 67%, 20%, 40%, and 39% of the samples, respectively. The single mutant pvdhfr 57 showed the strongest association with TF (odds ratio [OR], 9.04; P = .01). The combined presence of the quadruple mutant pvdhfr 57L+58R+61M+117T andpvmdrl mutation 976F was the best predictor of TF (OR, 8.56; P = .01). The difference in TF rates between sites was reflected in the genetic drug-resistance profile of the respective parasites. Conclusions. The present study identified a new molecular marker in pvmdrl that is associated with the in vivo response to AQ+SP. We suggest suitable marker sets with which to monitor P. vivax resistance against AQ+SP in countries where these drugs are used.

Background Severe malaria (SM) is classically associated with Plasmodium falciparum infection. Little information is available on the contribution of P. vivax to severe disease. There are some epidemiological indications that P. vivax or mixed infections protect against complications and deaths. A large morbidity surveillance conducted in an area where the four species coexist allowed us to estimate rates of SM among patients infected with one or several species. Methods and Findings This was a prospective cohort study conducted within the framework of the Malaria Vaccine Epidemiology and Evaluation Project. All presumptive malaria cases presenting at two rural health facilities over an 8-y period were investigated with history taking, clinical examination, and laboratory assessment. Case definition of SM was based on the World Health Organization (WHO) criteria adapted for the setting (i.e., clinical diagnosis of malaria associated with asexual blood stage parasitaemia and recent history of fits, or coma, or respiratory distress, or anaemia [haemoglobin < 5 g/dl]). Out of 17,201 presumptive malaria cases, 9,537 (55%) had a confirmed Plasmodium parasitaemia. Among those, 6.2% (95% confidence interval [CI] 5.7%–6.8%) fulfilled the case definition of SM, most of them in children, In a study carried out in Papua New Guinea, Blaise Genton and colleagues show thatPlasmodium vivax is associated with severe malaria., Editors' Summary Background. Malaria is a parasitic infection that is transmitted to people by infected mosquitoes. Four different parasites cause malaria—Plasmodium falciparum, P. vivax, P. ovale, and P. malariae. Of these, P. vivax is the commonest and most widely distributed, whereas P. falciparum causes the most deaths. All these parasites enter their human host when an infected mosquito takes a blood meal. They then migrate to the liver where they replicate without causing any symptoms. Eight to nine days later, mature parasites are released from the liver cells and invade red blood cells. Here, they multiply rapidly before bursting out and infecting more red blood cells. The recurring flu-like symptoms of malaria are caused by this cyclical increase in parasitemia (parasites in the blood) and should be treated promptly with antimalarial drugs to prevent the development of potentially fatal complications. Infections with P. falciparum in particular can cause anemia by destroying the red blood cells and can damage vital organs (including the brain) by blocking the capillaries that supply them with blood. Why Was This Study Done? It is generally believed that P. vivax malaria is rarely fatal. There is even some evidence that infection with P. vivax alone (monoinfection) or with other malaria parasites (mixed infection) provides protection against malarial complications. Recently, however, there have been reports of severe disease and deaths associated with infection by P. vivax alone. Most of these reports do not indicate what proportion of severe malaria cases are caused by P. vivax infections, but if P. vivax is responsible for a significant proportion of malarial deaths, efforts to prevent these deaths will need to target P. vivax as well as P. falciparum. In this study, therefore, the researchers estimate the proportion of cases of severe malaria among patients infected with one or several Plasmodium species in Papua New Guinea, a country where all four species coexist. What Did the Researchers Do and Find? The researchers enrolled everyone attending two rural health facilities in the Wosera subdistrict of Papua New Guinea over an eight-year period with symptoms indicative of malaria but without symptoms of any other disease (presumptive malaria cases) into their prospective cohort study. They asked each patient about their symptoms, did a standard physical examination, looked for parasites in their blood, and measured their hemoglobin levels to see whether they were anemic. Out of 17,201 presumptive malaria cases, 483 had severe malaria (defined as parasitemia plus a recent history of fits, coma, breathing problems, or anemia). Most of the patients with severe malaria were less than five years old—children have little immunity to Plasmodium parasites. In this age group, 11.7% of patients infected with P. falciparum, 8.8% of patients infected with P. vivax, and 17.3% of patients infected with both parasites had severe malaria. Patients with severe malaria caused by P. vivax presented with breathing difficulties more often than those infected with P. falciparum, whereas anemia was more common among patients with severe malaria caused by P. falciparum than by P. vivax. What Do These Findings Mean? The researchers use these results and data on the numbers of infections with each parasite to calculate that, in this rural region of Papua New Guinea, P. vivax is responsible for one-fifth of severe malaria cases, P. falciparum is responsible for three-quarters of cases, and the rest involve mixed P. falciparum/P. vivax infections. Put another way, these findings suggest that about one in ten children under the age of five years infected with either P. vivax or P. falciparum may develop severe malaria. These findings provide no evidence, however, that mixed infections are protective. Because the diagnosis of severe malaria was not confirmed by outcome data (deaths or permanent disability), additional, more detailed studies are needed to confirm these results. Nevertheless, these findings (and those reported separately in a related article published at the same time in PLoS Medicine) suggest that a significant proportion of the illness associated with malaria may be caused by P. vivax infections. Thus, efforts to reduce or eliminate the malarial burden must target P. vivax as well as P. falciparum in regions where these species coexist. Additional Information. Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0050127. A PLoSMedicine Research in Translation article by Stephen Rogerson further discusses this study and a related paper on vivax malaria infection in patients attending a regional hospital in Papua, Indonesia The MedlinePlus encyclopedia has a page on malaria (in English and Spanish) The US Centers for Disease Control and Prevention provides information on malaria (in English and Spanish) Information is available from the Roll Back Malaria Partnership on global control of malaria and on malaria in Papua New Guinea Vivaxmalaria provides information for the malaria research community on topics related to Plasmodiumvivax The Malaria Vaccine Initiative also provides a fact sheet on Plasmodiumvivax malaria

Background In Papua New Guinea (PNG), combination therapy with amodiaquine (AQ) or chloroquine (CQ) plus sulphadoxine-pyrimethamine (SP) was introduced as first-line treatment against uncomplicated malaria in 2000. Methods We assessed in vivo treatment failure rates with AQ+SP in two different areas in PNG and twenty-four molecular drug resistance markers of Plasmodium falciparum were characterized in pre-treatment samples. The aim of the study was to investigate the association between infecting genotype and treatment response in order to identify useful predictors of treatment failure with AQ+SP. Results In 2004, Day-28 treatment failure rates for AQ+SP were 29% in the Karimui and 19% in the South Wosera area, respectively. The strongest independent predictors for treatment failure with AQ+SP were pfmdr1 N86Y (OR = 7.87, p < 0.01) and pfdhps A437G (OR = 3.44, p < 0.01). Mutations found in CQ/AQ related markers pfcrt K76T, A220S, N326D, and I356L did not help to increase the predictive value, the most likely reason being that these mutations reached almost fixed levels. Though mutations in SP related markers pfdhfr S108N and C59R were not associated with treatment failure, they increased the predictive value of pfdhps A437G. The difference in treatment failure rate in the two sites was reflected in the corresponding genetic profile of the parasite populations, with significant differences seen in the allele frequencies of mutant pfmdr1 N86Y, pfmdr1 Y184F, pfcrt A220S, and pfdhps A437G. Conclusion The study provides evidence for high levels of resistance to the combination regimen of AQ+SP in PNG and indicates which of the many molecular markers analysed are useful for the monitoring of parasite resistance to combinations with AQ+SP.

Summary We describe here the results of an analysis of Plasmodium falciparum multidrug resistance protein 1 (pfmdr1) gene copy number from 440 field isolates from Papua New Guinea. No multiple copies of the gene were found, which corresponds to the lack of usage of mefloquine. These data extend regional knowledge about the distribution of multidrug-resistant P. falciparum.

Schistosomes and soil-transmitted helminths currently infect a third of the world's human population. An important feature of these parasitic infections is their focal distribution, which has significant implications for control. Only a few studies have been carried out at the microepidemiological scale, comparing infection levels among individuals or households within a single village. In this study, data are presented from a cross-sectional survey, examining all children attending a primary school in rural Côte d'Ivoire over several consecutive days for Schistosoma mansoni, soil-transmitted helminths, and intestinal protozoa. All houses in the main village were mapped, and school children were linked to these households for small-area spatial analyses. Comparison between the 260 school children who live within the main village and the 89 children who reside in nearby settlements revealed significant differences in the overall prevalence and intensity of infections with S. mansoni and hookworm, confirming the focal nature of these 2 parasites. On the other hand, S. mansoni and hookworm infections exhibited random spatial patterns within the main village. The validity of these results is discussed in the context of this epidemiological setting, drawing attention to the issue of scale. Our findings have direct implications for intervention because they call for a uniform, community-wide approach to control schistosomiasis and soil-transmitted helminthiasis. Implementation can be relatively straightforward, and the proposed control approach might be cost-effective and prove sustainable.

Papua New Guinea (PNG) is a patchwork of different ecological zones, inhabited by human populations of exceptional cultural and linguistic diversity. This results in complex variations in vector ecology and malaria epidemiology. Malaria is the main cause of morbidity in many health facilities in lowland areas, but it is absent in much of the highlands. All four human malaria species occur, but endemicity varies widely, with Plasmodium falciparum locally reaching holo-endemic levels that are rarely found outside sub-Saharan Africa. The high frequency of Plasmodium vivax is an important difference to most African situations. PNG is therefore a prime location for studies of interactions between different parasite species, and of the biology of local human genetic adaptation and its implications for malaria morbidity and mortality.

We present the comparative evaluation of school-based chemotherapy with praziquantel on Schistosoma haematobium reinfection patterns, 6, 12, 18 and 24 months after systematic treatment of schoolchildren in four villages of south-central Cote d'Ivoire. At baseline, very high S. haematobium infection prevalences of 88-94% were found in Taabo Village, located adjacent to a large man-made lake, and in Batera and Bodo, where small dams were constructed. In Assinze, a village with no man-made environmental alterations, the baseline infection prevalence was significantly lower (67%). The parasitological cure rate, assessed 4 weeks after praziquantel administration in the village with the highest prevalence and intensity of infection, was high (82%), and showed a clear association with infection intensity prior to treatment. Six months after chemotherapy, significant reductions in the prevalence and intensity of infection were observed in all villages. However, infection prevalence was again high in Taabo Village (63%) and in Batera (49%). Different patterns of reinfection occurred in the four villages: rapid reinfection in Taabo Village to reach almost baseline infection prevalence 12 months post-treatment; slow but gradual increase in the prevalence and intensity of infection in Bodo; marked increase in prevalence and intensity of infection during the second year of the follow-up in Assinze; and prevalence and intensity of infection that remained almost constant between 6 and 24 months post-treatment in Batera. Our study confirms that S. haematobium reinfection patterns largely depend on the local epidemiological setting, which is of central importance to tailoring treatment strategies that are well adapted to these different settings.

Effects of bednet coverage (C) on prevalence of malaria were analysed using data from 1990-92 from 9 Papua New Guinean villages. Effects of coverage varied by age, resulting in a shift in age of peak prevalence from 4.7 (C = 0%) to 11.6 (C = 100%) years for Plasmodium falciparum, from 3.4 to 4.9 years for P. vivax and from 11.0 to 16.8 years for P. malariae. In small areas with no bednets the age distribution of P. falciparum parasitaemia was like that of a holoendemic area. Where coverage was complete the pattern corresponded to mesoendemicity. Thus, protracted use of bednets can result in profound changes in the endemicity of malaria even when coverage is incomplete and without insecticide treatment. Average entomological inoculation rates (EIRs) estimated from indoor landing rates on individuals without bednets were 35, 12 and 10 infectious bites per person per annum for P. falciparum, P. vivax and P. malariae, respectively. Logistic regression analyses indicated that the EIR estimate for P. falciparum was related to prevalence of this species independently of effects of bednet coverage. However, the recent EIR still accounted for much less variation than did the bednets. A similar pattern was seen for P. malariae, while there were no significant relationships between the recent EIR and the parasite positivity for P. vivax. It is concluded that short-term variations in inoculation rate are not important determinants of parasite prevalence in this population.

The willingness of patients in the rural tropics to seek medical care at primary health care facilities is influenced by the distance they have to travel, but few studies have tried to estimate these distance effects.Distance decay effects in attendance rates were estimated from a database of 4348 attendances at a rural health centre in Papua New Guinea, linked to demographic and house position data for the catchment population. Small-scale spatial patterns and differences between diagnoses, age groups and gender are described.Attendance decreased markedly with distance both overall (50% decrease at 3.5 km) and for patients with malaria or acute respiratory infections. This decrease was non-linear (on log scale) with distance. Although constant over time, there were big differences in this distance effect among age and gender groups: Female patients showed less distance decay in adolescents and adults, but higher in the infant group. Spatial patterns accounted for 32% of the variation in age- and gender-specific attendance rates. Of the spatial effects more than 50% were due to distance effects.Distance effects were similar in magnitude to those reported elsewhere, suggesting that distance effects may be generalizable to many parts of the rural tropics. The non-linearity of distance decay implies that a bell-shaped demand function should be used in health planning.

Background Molecular monitoring of parasite resistance has become an important complementary tool in establishing rational anti-malarial drug policies. Community surveys provide a representative sample of the parasite population and can be carried out more rapidly than accrual of samples from clinical cases, but it is not known whether the frequencies of genetic resistance markers in clinical cases differ from those in the overall population, or whether such community surveys can provide good predictions of treatment failure rates. Methods Between 2003 and 2005, in vivo drug efficacy of amodiaquine or chloroquine plus sulphadoxine-pyrimethamine was determined at three sites in Papua New Guinea. The genetic drug resistance profile (i.e., 33 single nucleotide polymorphisms in Plasmodium falciparum crt, mdr1, dhfr, dhps, and ATPase6) was concurrently assessed in 639 community samples collected in the catchment areas of the respective health facilities by using a DNA microarray-based method. Mutant allele and haplotype frequencies were determined and their relationship with treatment failure rates at each site in each year was investigated. Results PCR-corrected in vivo treatment failure rates were between 12% and 28% and varied by site and year with variable longitudinal trends. In the community samples, the frequencies of mutations in pfcrt and pfmdr1 were high and did not show significant changes over time. Mutant allele frequencies in pfdhfr were moderate and those in pfdhps were low. No mutations were detected in pfATPase6. There was much more variation between sites than temporal, within-site, variation in allele and haplotype frequencies. This variation did not correlate well with treatment failure rates. Allele and haplotype frequencies were very similar in clinical and community samples from the same site. Conclusions The relationship between parasite genetics and in vivo treatment failure rate is not straightforward. The frequencies of genetic anti-malarial resistance markers appear to be very similar in community and clinical samples, but cannot be used to make precise predictions of clinical outcome. Thus, indicators based on molecular data have to be considered with caution and interpreted in the local context, especially with regard to prior drug usage and level of pre-existing immunity. Testing community samples for molecular drug resistance markers is a complementary tool that should help decision-making for the best treatment options and appropriate potential alternatives.

BACKGROUND: Asymptomatic individuals are one of the major challenges for malaria elimination programs in endemic areas. In the absence of clinical symptoms and with a lower parasite density they constitute silent reservoirs considered important for maintaining transmission of human malaria. Studies from Brazil have shown that infected individuals may carry these parasites for long periods. RESULTS: Patients were selected from three periurban endemic areas of the city of Manaus, in the western Brazilian Amazon. Symptomatic and asymptomatic patients with positive thick blood smear and quantitative real-time PCR (qPCR) positive for Plasmodium vivax were invited to participate in the study. A standardised pvs25 gene amplification by qPCR was used for P. vivax gametocytes detection. Anopheles aquasalis were fed using membrane feeding assays (MFA) containing blood from malaria patients. Parasitemia of 42 symptomatic and 25 asymptomatic individuals was determined by microscopic examination of blood smears and qPCR. Parasitemia density and gametocyte density were assessed as determinants of infection rates and oocysts densities. A strong correlation between gametocyte densities (microscopy and molecular techniques) and mosquito infectivity (P < 0.001) and oocysts median numbers (P < 0.05) was found in both groups. The ability to infect mosquitoes was higher in the symptomatic group (41%), but infectivity in the asymptomatic group was also seen (1.42%). CONCLUSIONS: Although their infectivity to mosquitoes is relatively low, given the high prevalence of P. vivax asymptomatic carriers they are likely to play and important role in malaria transmission in the city of Manaus. The role of asymptomatic infections therefore needs to be considered in future malaria elimination programs in Brazil.