High prevalence of ectopic kidney in Coast Province, Kenya

OBJECTIVE: To establish the prevalence of congenital urinary tract abnormalities in a full population-based ultrasound survey of an area of coastal Kenya. METHODS: Ultrasound examination of 3118 residents of 912 households, including all available subjects over 2 years of age, residing in five contiguous rural villages 50 km south of Mombasa. RESULTS: Survey findings indicated simple renal ectopia in 11 of 3118 subjects (0.35%) and renal agenesis in three (0.096%). No cases of horseshoe kidney or complex urinary anomaly were detected, and no cases of multiple congenital anomaly were found. Ectopia cases were evenly distributed between men and women, and across the five study villages. None of the individuals affected by renal ectopia were closely related (i.e. <5th-degree relations). CONCLUSION: There is an unusually high prevalence of ectopia among unrelated subjects in this area. In this setting, the findings suggest either a common exposure to teratogenetic factors, or a hereditary condition with variable penetrance, where more severely affected individuals are not observed because of foetal/infant mortality.     

Spatial and temporal variations in local transmission of Schistosoma haematobium in Msambweni, Kenya

As part of an extensive study of the eco-epidemiology of urinary schistosomiasis along the southern coast of Kenya, spatial and temporal transmission patterns were associated with various ponds infested with Bulinus snails. The household-level spatial pattern of infection for children of various age groups in 2000 was contrasted with historical data from 1984. Significant local clustering of high and low infection levels among school age children was detected, and the spatial extent of clusters and their direction from specific water sources were measured. High infection levels were clustered around ponds known to contain Bulinus nasutus snails that shed Schistosoma haematobium cercariae, and low infection levels were concentrated near a river where intermediate host snails were rarely found. The spatial patterns of infection varied between 2000 and 1984 and between age groups. High levels of infection were clustered around different transmission foci in the two study periods, and, for younger children in 2000, were clustered nearer to the transmission foci than for the older children. Simultaneous consideration of the effects of different foci on transmission will allow for targeted application of control measures aimed at interrupting S. haematobium transmission at a local level.     

安徽省感染性钉螺分布现状与调查

目的了解安徽省血吸虫感染性钉螺分布现状与特点。方法2007年收集安徽省钉螺调查的数据和各感染性螺点的GPS定位数据,建立感染性钉螺分布空间数据库,用ArcGis9．1绘制电子地图,分析全省感染性钉螺分布现状。结果2007年全省查出331处感染性钉螺环境,其中湖沼型流行区占62．5％,山丘型流行区占37．5％;现有感染性钉螺面积682．6hm^2,其中湖沼型地区占85．5％,山丘型流行区占14．5％。江滩和沟渠分别是湖沼型和山丘型流行区感染性钉螺分布最多的环境;97．2％的感染性钉螺环境分布于未控制村和疫情控制村。草是感染性钉螺分布最多的植被,其次为芦苇与树林。结论全省感染性钉螺的分布与水系的分布关系密切,湖沼型地区感染性钉螺分布在长江的两岸江滩、洲滩及其支流水系的河滩、湖泊的湖滩,山丘型地区感染性钉螺分布在河流、灌区或多种特殊环境。     

Urinary tract morbidity in schistosomiasis haematobia: associations with age and intensity of infection in an endemic area of Coast Province, Kenya

To gain better understanding of the natural history of Schistosoma haematobium associated disease, age- and intensity-related urinary tract morbidity were assessed in a cross-sectional study of Kilole (population 719) in Coast Province, Kenya. Overall prevalence of infection was 65% (39% light, 16% moderate, 9% heavy). Infection prevalence and mean intensity of infection were highest in the 5-14-year-old bracket for both sexes. Although significant intensity-associated increases in hematuria prevalence were noted for both children and adults in all infection categories, hematuria was more common in those less than 15 years of age. Children had a significant increase in the prevalence of dysuria at higher levels of infection, whereas adults did not. Radiographic study of a 1:9 random sample, stratified for age, revealed a greater prevalence of urinary tract granulomas in those less than 15 years. Subjects greater than 15 years of age had a greater frequency of hydronephrosis. Hydronephrosis, hydroureter, and bladder calcification were not associated with higher infection intensity. Among individuals with bladder calcification, a potential marker of cumulative inflammation, 87% had hydronephrosis or hydroureter, compared to a 40% prevalence among individuals without bladder calcification. These findings suggest that certain structural forms of urinary tract disease, such as hydronephrosis, progress during the course of untreated schistosomiasis haematobia despite age-related reductions in egg burden, whereas other forms of morbidity, such as hematuria, remain sensitive to the level of urinary egg excretion at the time of diagnosis.     

Bancroftian filariasis in 12 villages in Kwale district, Coast province, Kenya - variation in clinical and parasitological patterns

As part of a larger study on the effects of permethrin-impregnated bednets on the transmission of Wuchereria bancrofti, subjects from 12 villages in the Coastal province of Kenya, south of Mombasa, were investigated. The aims were to update the epidemiological data and elucidate the spatial distribution of W. bancrofti infection. Samples of night blood from all the villagers aged i 1 year were checked for the parasite, and all the adult villagers (aged >/= 15 years) were clinically examined for elephantiasis and, if male, for hydrocele. Overall, 16.0% of the 6531 villagers checked for microfilariae (mff) were found microfilaraemic, although the prevalence of microfilaraemia in each village varied from 8.1%-27.4%. The geometric mean intensity of infection among the microfilaraemic was 322 mff/ml blood. At village level, intensity of the microfilaraemia was positively correlated with prevalence, indicating that transmission has a major influence on the prevalence of microfilaraemia. Clinical examination of 2481 adults revealed that 2.9% had elephantiasis of the leg and that 19.9% of the adult men (10.8%-30.1% of the men investigated in each village) had hydrocele. Although the overall prevalence of microfilaraemia in the study villages had not changed much since earlier studies in the 1970s, both prevalence and intensity varied distinctly between the study villages. Such geographical variation over relatively short distances appears to be a common but seldom demonstrated feature in the epidemiology of bancroftian filariasis, and the focal nature of the geographical distribution should be carefully considered by those mapping the disease.     

Effects of borehole wells on water utilization in Schistosoma haematobium endemic communities in Coast Province, Kenya

To determine the impact of the introduction of borehole wells on water use patterns and the consequent risk of transmission of Schistosoma haematobium in 3 endemic villages in Kenya, we performed a survey (a 1:6 sample of affected households) to identify sources of water and types of water utilization before and after well introduction. Water usage was also determined in 2 unaffected neighboring villages not given borehole wells, but having continuous access to piped water from communal taps. Prior to borehole well construction, significantly more high-risk water use occurred in the borehole villages vs. comparison villages in terms of water gathered for cooking, drinking, dish washing, and bathing; residents of both types of villages preferred high-risk sources (marshes and ponds) for clothes washing. Following well introduction, there were significant declines in the use of high-risk water for drinking, cooking, and dish washing, but not for bathing or clothes washing. A higher proportion of individuals from the 3 borehole villages reported some type of continued contact with high-risk water sources. Despite well introduction and a 3 year chemotherapy program among school-aged children, a 21-28% incidence of infection persisted among children in the villages, suggesting minimal impact on transmission. Regular monitoring for S. haematobium infected snail sites showed no decline in the number or proportion of infected snails. Borehole well introduction can significantly alter some forms of water usage, but social and water quality factors may limit the ability of communal wells to reduce S. haematobium transmission.     

Diversity and cercarial shedding of malaco fauna collected from water bodies of Ratnagiri district, Maharashtra

An investigation on the occurrence of snails in the water bodies of five selected sites i.e., Khed, Chiplun, Ratnagiri, Parchuri and Gimvi of district Ratnagiri, Maharashtra (India) was made during April-May 2006. The study revealed occurrence of nine species of snails viz., Indoplanorbis exustus, Lymnaea luteola, L. acuminata, Paludomus obesus, Ferrissia tenuis, Thiara (Melanoides) tuberculata, Bellamya bengalensis, B. dissimilis and Pila globosa, besides some species of bivalves. I. exustus was the most common species by occurrence in all the selected localities and next to it was L. luteola followed by T. tuberculata, B. bengalensis and B. dissimilis, in succession. Infection with liverfluke and amphistome cercariae was found in most of the collected snail species except P. globosa. However, the Schistosome infection has been reported only in I. exustus and L. luteola. The rice fields, streams and riverbeds shared most abundance of snails whereas those collected from rice fields shedded highest number of cercariae.     

2010—2021年安徽省宿松县钉螺分布特征分析

目的 了解宿松县钉螺分布特征及变化趋势,为制定血吸虫病防治措施提供依据。方法 采用回顾性研究方法,收集2010—2021年宿松县螺情资料,统计钉螺面积、活螺密度、活螺框出现率等指标,分析全县及不同类型流行区钉螺分布及变化趋势。结果 2010—2021年,宿松县钉螺面积为1 672.60～2 171.57 hm²,总体平稳,其中江滩型流行区钉螺面积为985.74～1 235.64 hm²,波动较小;湖沼型流行区钉螺面积为181.44～284.78 hm²,呈下降趋势;内陆型流行区钉螺面积为399.77～750.02 hm²,呈上升趋势。全县活螺密度为0.16～0.75只/0.11 m2,活螺框出现率为5.11%～11.78%。江滩型流行区和湖沼型流行区活螺密度相对平稳,内陆型流行区活螺密度呈现先降后升趋势;不同类型流行区活螺框出现率年度波动较大。2013年起全县未再查获感染性钉螺。结论 宿松县螺情总体平稳,但内陆型流行区螺情有扩散趋势,今后应重点加强内陆型流行区钉螺监测与控制工作,以巩固防治成果。     

东洞庭湖钉螺自然消亡地区单壳类软体动物分布调查

目的 目的 了解东洞庭湖钉螺自然消亡地区单壳类软体动物的分布, 探索钉螺消亡的可能原因, 为制定血吸虫病防治策略提供参考依据。方法 方法 于2013年8月对钱粮湖、 建新、 君山公园地区进行水体单壳类软体动物调查, 对样本进行分类鉴定后, 对数据进行Shapiro?Wilk正态性检验和非参数检验。用生物多样性指数对不同现场的生物多样性进行比较。结果 结果 所收集样本初步鉴定为腹足纲3科6种：圆口螺科包括湖北钉螺, 豆螺科包括纹沼螺、 长角涵螺、 中华沼螺、 赤豆螺,椎实螺科1种未鉴定到种, 暂定为萝卜螺。君山公园外洲水体共采集到单壳类软体动物4 553只, 其中钉螺1 264只; 建新未采集到钉螺, 其余单壳类软体动物共计336只; 而钱粮湖仅采集到7只长角涵螺、 2只中华沼螺和1只纹沼螺。3个现场螺类分布的差异有统计学意义 （χ2=166.225, P＜0.01）。钱粮湖地区、 建新地区及君山公园的辛普森多样性指数分别为0.402 8、 0.718 6及0.678 8, 香农?威纳多样性指数分别为0.721 5、 1.431 3及1.199 9。结论 结论 钱粮湖地区钉螺消亡的同时, 其他种类单壳类软体动物无论是种类上还是数量上都已十分稀少, 两者原因是否相关还有待进一步研究。     

东洞庭湖钉螺自然消亡地区单壳类软体动物分布调查

目的了解东洞庭湖钉螺自然消亡地区单壳类软体动物的分布,探索钉螺消亡的可能原因,为制定血吸虫病防治策略提供参考依据。方法于2013年8月对钱粮湖、建新、君山公园地区进行水体单壳类软体动物调食,对样本进行分类鉴定后,对数据进行Shapiro-Wilk正态性检验和非参数检验。用生物多样性指数对不同现场的生物多样性进行比较。结果所收集样奉初步鉴定为腹足纲3科6种：圆口螺科包括湖北钉螺,豆螺科包括纹沼螺、长角涵螺、中华沼螺、赤豆螺,椎实螺科1种未鉴定到种,暂定为萝卜螺。君山公园外洲水体共采集到单壳类软体动物4553只,其中钉螺1264只;建新未采集到钉螺,其余单壳类软体动物共计336只;而钱粮湖仅采集到7只长角涵螺、2只中华沼螺和1只纹沼螺。3个现场螺类分布的差异有统计学意义（X^2=166．225,P〈0．01）。钱粮湖地区、建新地区及稽山公园的辛普森多样性指数分别为0．4028、0．7186及0．6788,香农一威纳多样性指数分别为0．7215、1．4313及1．1999。结论钱粮湖地区钉螺消亡的同时,其他种类单壳类软体动物无论是种类上还是数量上都已十分稀少,两者原因是否相关还有待进一步研究。     

Spatial patterns of urinary schistosomiasis infection in a highly endemic area of coastal Kenya

Urinary schistosomiasis remains a major contributor to the disease burden along the southern coast of Kenya. Selective identification of transmission hot spots offers the potential for more effective, highly-focal snail control and human chemotherapy to reduce Schistosoma haematobium transmission. In the present study, a geographic information system was used to integrate demographic, parasitologic, and household location data for an endemic village and neighboring households with the biotic, abiotic, and location data for snail collection/water contact sites. A global spatial statistic was used to detect area-wide trends of clustering for human infection at the household level. Local spatial statistics were then applied to detect specific household clusters of infection, and, as a focal spatial statistic, to evaluate clustering of infection around a putative transmission site. High infection intensities were clustered significantly around a water contact site with high numbers of snails shedding S. haematobium cercariae. When age was considered, clustering was found to be significant at different distances for different age groups.     

The influence of stream geology on the distribution of the bilharzia host snails, Biomphalaria pfeifferi and Bulinus (physopsis) sp.

The Gladdespruit and Komati River surveys have shown that similar environmental conditions have developed where the watercourses flowed over particular rock types. In these watercourses a potentially useful association was found between the occurrence of permanent, lentic habitats produced by the weathering of bedrock with a hardness above 5 in Mohs' Scale of Hardness and the longitudinal distribution of persistent populations of the bilharzia intermediate host snails Biomphalaria pfeifferi and Bulinus (Physopsis) sp. Bilharzia transmission follows this pattern in these waterways. Weathering of bedrock with hardness below 5 in Mohs' scale, and/or flow over beds of alluvial sand, produced perpetually lotic (flowing) environments without persistent host snail populations because of the snail's inability to tolerate high current speeds. However a few temporary populations survived in temporarily lentic habitats during the dry winter season.