Cercariometry for detection of transmission sites for schistosomiasis

Aoki, Yoshiki; Sato, Katsuyuki; Muhoho, Ngethe D.; Noda, Shinichi; Kimura, Eizen

doi:10.1016/s1383-5769(03)00057-6

Cited by 28 publications

(37 citation statements)

References 11 publications

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“…Conventional microscopic quantitation is used to detect cercariae in natural water sources and has been applied to describe the diurnal variation, seasonal patterns, and spatial distribution of cercariae (333,334). However, this approach has the limitations common to the other conventional techniques discussed above.…”

Section: Detection Of Infected Intermediate Snail Hostsmentioning

confidence: 99%

Advances in the Diagnosis of Human Schistosomiasis

et al. 2015

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SUMMARY Schistosomiasis is a major neglected tropical disease that afflicts more than 240 million people, including many children and young adults, in the tropics and subtropics. The disease is characterized by chronic infections with significant residual morbidity and is of considerable public health importance, with substantial socioeconomic impacts on impoverished communities. Morbidity reduction and eventual elimination through integrated intervention measures are the focuses of current schistosomiasis control programs. Precise diagnosis of schistosome infections, in both mammalian and snail intermediate hosts, will play a pivotal role in achieving these goals. Nevertheless, despite extensive efforts over several decades, the search for sensitive and specific diagnostics for schistosomiasis is ongoing. Here we review the area, paying attention to earlier approaches but emphasizing recent developments in the search for new diagnostics for schistosomiasis with practical applications in the research laboratory, the clinic, and the field. Careful and rigorous validation of these assays and their cost-effectiveness will be needed, however, prior to their adoption in support of policy decisions for national public health programs aimed at the control and elimination of schistosomiasis.

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Section: Detection Of Infected Intermediate Snail Hostsmentioning

confidence: 99%

Advances in the Diagnosis of Human Schistosomiasis

et al. 2015

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“…Nevertheless, the number of cercariae present in a habitat is directly proportional to the number of infected molluscs (Upatham, 1976;Muhoho et al, 1997). However, it is difficult to establish a precise relationship between the cercarial densities and the number of infected snails because of the complexities of hydrodynamical processes, mollusc distribution and cercarial emission patterns found in any individual aquatic habitat (Aoki et al, 2003). Consequently, sampling infected molluscs alone is not an adequate substitute for direct measurement of cercarial populations.…”

Section: Population Dynamics Of Cercariaementioning

confidence: 99%

“…In contrast, studies in a river in Texas, USA, found the largest cercarial densities were recorded at the most downstream site where the flow was the highest (Johnson et al, 2012) suggesting that the physical and hydrodynamical characteristics of a flowing water site determine the density of the parasite population at any single locality. In still water habitats, as many as 200-300 cercariae/l can occur and may be the most abundant zooplankton animals collected (Theron et al, 1978;Ueda & Kimura, 2001), although more typical recoveries of less than 10/l have been achieved (Aoki et al, 2003). High densities of cercariae are particularly found along the shoreline of lakes and ponds, probably associated with the action of onshore winds and the distribution of infected molluscan hosts.…”

Section: Population Dynamics Of Cercariaementioning

confidence: 99%

Cercariae (Platyhelminthes: Trematoda) as neglected components of zooplankton communities in freshwater habitats

Morley

2012

Hydrobiologia

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Zooplanktonic animals live in the open water of freshwater habitats, whilst trematodes are ubiquitous parasitic worms of aquatic vertebrates and invertebrates. A defining characteristic of trematode life cycles is the cercariae, a mainly planktonic freeliving larval stage that emerges into the aquatic environment from infected molluscan hosts. Cercariae are lecithotrophic (non-feeding) larvae analogous of meroplankton. Although millions of planktonic cercariae enter freshwater habitats on a daily basis and are capable of forming into dense clouds, they are a largely neglected component of the zooplankton community, rarely mentioned in faunal studies. Nevertheless, there is increasing evidence to suggest that cercariae have important secondary roles in aquatic food webs and energy transfer. This article reacquaints freshwater biologists with cercariae, highlighting the key characteristics of their biology and population dynamics, their role in food webs, public health and veterinary importance, and the risk of increased population densities under the influence of climate change. The reasons for their neglect in freshwater biology is evaluated and considered to be associated with zooplankton sampling methodologies being unsuitable for collecting cercariae and the paucity of identification keys in the limnological literature.

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“…Among these are monitoring of human water use activity, 10,11 estimation of egg contamination of water by human excreta, 12 detection of cercarial shedding by snails, 13 and cercariometry. 14,15 Of these approaches, cercarial shedding has been most extensively used (in combination with human water contact data) to provide estimates of snail-to-human transmission. However, cercarial shedding can be highly focal 16 and of low frequency, even in areas of significant transmission.…”

Section: Introductionmentioning

confidence: 99%

Detection of Schistosoma mansoni and Schistosoma haematobium DNA by Loop-Mediated Isothermal Amplification: Identification of Infected Snails from Early Prepatency

Abbasi¹,

King²,

Muchiri³

et al. 2010

The American Society of Tropical Medicine and Hygiene

105

126

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Monitoring post-control transmission of schistosomes by examining humans becomes less effective as infection rates among humans decrease. Molecular monitoring of prepatent schistosome infection in snails by the polymerase chain reaction (PCR) has been used for studying human-to-snail transmission, and snail prepatent infection rates were found to correspond to infection prevalence and average intensity in human populations contacting the sites studied. We have now developed loop-mediated isothermal amplification (LAMP) assays for identifying Schistosoma mansoni and S. haematobium to facilitate large-scale evaluation of post-intervention transmission potential. LAMP primers were designed based on the Sm1-7 and DraI repeated sequences of the corresponding schistosomes, and amplification by LAMP of these 121-basepair highly abundant sequences provided a detection sensitivity of 0.1 fg of genomic DNA. When these LAMP assays were applied for examining infected laboratory snails, it was possible to identify infection from the first day after exposure to miracidia. The potential advantages of these assays are discussed.

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Cercariometry for detection of transmission sites for schistosomiasis

Cited by 28 publications

References 11 publications

Advances in the Diagnosis of Human Schistosomiasis

Advances in the Diagnosis of Human Schistosomiasis

Cercariae (Platyhelminthes: Trematoda) as neglected components of zooplankton communities in freshwater habitats

Detection of Schistosoma mansoni and Schistosoma haematobium DNA by Loop-Mediated Isothermal Amplification: Identification of Infected Snails from Early Prepatency

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