Background Strongyloides stercoralis is a neglected soil-transmitted helminth species, and there is a lack of parasitologic and epidemiologic data pertaining to this parasite in China and elsewhere. We studied the local occurrence of S. stercoralis in a village in Yunnan province, China, and comparatively assessed the performance of different diagnostic methods.Methodology/Principal FindingsMultiple stool samples from a random population sample were subjected to the Kato-Katz method, an ether-concentration technique, the Koga agar plate method, and the Baermann technique. Among 180 participants who submitted at least 2 stool samples, we found a S. stercoralis prevalence of 11.7%. Males had a significantly higher prevalence than females (18.3% versus 6.1%, p = 0.011), and infections were absent in individuals <15 years of age. Infections were only detected by the Baermann (highest sensitivity) and the Koga agar plate method, but neither with the Kato-Katz nor an ether-concentration technique. The examination of 3 stool samples rather than a single one resulted in the detection of 62% and 100% more infections when employing the Koga agar plate and the Baermann technique, respectively. The use of a mathematical model revealed a ‘true’ S. stercoralis prevalence in the current setting of up to 16.3%.Conclusions/SignificanceWe conclude that S. stercoralis is endemic in the southern part of Yunnan province and that differential diagnosis and integrated control of intestinal helminth infections needs more pointed emphasis in rural China.

[1] Warm conveyor belts (WCBs) and frontal activity play important roles in the longrange transport of air pollutants by lifting them from the planetary boundary layer (PBL) into the free troposphere (FT) in midlatitudes. In summer 2007, an aircraft study was carried out in northeast (NE) China in order to understand the role of midlatitude cyclones in air pollution transport in north and east China in warm seasons. During a flight on 27 June, high concentrations of ozone and related trace gases were observed, with maximum concentrations (O 3 $ 140 ppbv, SO 2 $ 14.6 ppbv, CO $ 1185 ppbv) recorded at an altitude of 2.6 km. In this paper we present a detailed analysis of this flight. The mesoscale meteorological model Weather Research and Forecasting (WRF) and a Lagrangian dispersion model called FLEXPART were used to aid the diagnostic analysis of the atmospheric dynamic structure and the understanding of the transport characteristics of regional and local air pollution. The flight took place in a region adjacent to a warm front associated with a weak cyclone in north China. The aircraft sampled both the WCB and warm air frontal zone of the cyclone. The simulations show that the observed high air pollution in the FT mostly originated from the North China Plain, especially the megacities Beijing and Tianjin. Their plumes were vented by a stagnant front, probably through, in part, topographic lifting by the mountains in the north, and then were quickly transported in the FT to the study region. Trajectory analysis and satellite data suggest that the observed air masses were further lifted by the WCB into the middle and upper troposphere and were exported from Asia toward North America and the Arctic.

Intestinal multiparasitism, the accuracy of different diagnostic techniques, and the influence of sampling effort were studied among 215 individuals in a Bulang village, Yunnan province, People's Republic of China. Behavioral, demographic, and socioeconomic data were obtained by questionnaire. Multiple stool specimens were examined by the Kato-Katz, Koga agar plate, Baermann, and ether-concentration methods. Eight helminth and 7 protozoa species were diagnosed. The prevalence of each of the 3 main soil-transmitted helminths (Ascaris lumbricoides, hookworm, and Trichuris trichiura) exceeded 85%. Blastocystis hominis was the most prevalent intestinal protozoan (20.0%). Over 80% of the individuals harbored 3 or more intestinal parasites concurrently. The infection intensities were predominantly light for hookworm and T. trichiura but moderate for A. lumbricoides. Examination of 3 instead of 1 stool specimen increased the sensitivity of helminth diagnosis, most notably for hookworm. Intestinal multiparasitism is rampant in this rural part of Yunnan province and calls for control measures.

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BackgroundChronic soil-transmitted helminth (STH) infections have been associated with reduced physical fitness, but available evidence is limited. The aim of this cross-sectional survey was to assess the feasibility of measuring children's physical fitness and to relate it to STH infections. Our study was carried out among school-aged children of the Bulang ethnic group in rural southwest People's Republic of China (P.R. China). Standardized, quality-controlled methods were employed to determine STH infections (Kato-Katz technique), haemoglobin levels, anthropometry (body weight and height) and physical fitness (20-m shuttle run test).ResultsA compliance of 87% suggested good acceptance of the methods used. Among 69 children with complete data records, infection prevalence of Trichuris trichiura, Ascaris lumbricoides and hookworm were 81%, 44% and 6%, respectively. The maximum volume of oxygen that can be utilized within 1 min during exhaustive exercise (VO2 max estimate) of T. trichiura-infected children was 1.94 ml kg-1 min-1 lower than that of their non-infected counterparts (P = 0.005). Until exhaustion, T. trichiura-infected children had completed 6.14 20-m laps less (P = 0.004). Additionally, the mean VO2 max estimate of stunted children was lowered by 1.63 ml kg-1 min-1 (P = 0.002) and they completed 5.32 20-m laps less (P = 0.001) compared to children of normal stature. No significant association between stunting and infection with any STH species could be established.ConclusionsImplementation of physical fitness tests in rural, resource-constraint settings is feasible. The physical fitness of children who are stunted or infected with STHs, particularly T. trichiura, is significantly impaired. We have launched a larger study and will determine the dynamics of school-aged children's physical fitness over a 7-month period after administration of anthelminthic drugs.