Detection of Schistosoma mansoni in Biomphalaria Using Nested PCR

Hanelt, Ben; Adema, Coen M.; Mansour, Mohamed H.; Loker, Eric S.

doi:10.2307/3284399

Cited by 47 publications

(38 citation statements)

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“…9 Recently, a PCR assay based on amplification of a mitochondrial DNA minisatellite region enabled detection of infected snails from one week after snail exposure to 10 miracidia, 10 and another assay based on a nested PCR of 18S rDNA sequences also enabled the detection of infected snails one day after exposure to a single miracidium, but this required two successive PCRs, its sensitivity was somewhat lower, and testing of pools of samples was not attempted. 11 The early and sensitive detection of snails infected with a single miracidium, and the possibility of testing pools of DNA samples (Figure 3), as described in the present study and discussed below, is expected to be useful for large-scale screening of snail populations in nature. Furthermore, the clear positive versus negative differentiation between infected and uninfected snails should be superior to differentiation by banding pattern of the PCR products as shown by others.…”

Section: Discussionmentioning

confidence: 89%

“…9 Detection of prepatent infections of snails has also been accomplished very recently by polymerase chain reaction (PCR) amplification of the mitochondrial DNA minisatellite region of S. mansoni, 10 and by nested PCR amplification of 18S sequences of rDNA. 11 A reliable and efficient detection of prepatent infections in snails from very early stages after the invasion of a miracidium, especially if manageable for routine largescale tests, should enable an extended outlook on the epidemiology of schistosome infection of snails, and facilitate mathematical modeling of transmission. 12,13 Early detection of prepatent infections of snails may also enable early detection of the effect of community-based control measures on transmission if control should affect the degree of water contamination by schistosome eggs as do a variety of other factors.…”

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confidence: 99%

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A polymerase chain reaction assay for detecting snails infected with bilharzia parasites (Schistosoma mansoni) from very early prepatency.

Hamburger¹,

He-Na²,

Xin³

et al. 1998

The American Journal of Tropical Medicine and Hygiene

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Abstract. In the present study, we adapted a polymerase chain reaction (PCR) assay, previously shown by us to be very sensitive for detecting cercariae in water, for the sensitive detection of Schistosoma mansoni DNA in infected snails from early prepatency. Polymerase chain reaction primers were designed based on the 121-basepair highly repeated sequence we previously identified in the genome of S. mansoni. The DNA was prepared from the snails by a simple alkaline extraction procedure, and the PCR assay enabled a clear differentiation between infected and normal snails. Infected snails were detected as early as one day after penetration of a single miracidium. The high sensitivity of the test enabled identification of a single infected snail even when its DNA was pooled with material from up to 99 uninfected snails, thus demonstrating the possibility of mass diagnosis in pools of snails. The assay has the potential for large-scale determination of prepatent infection prevalence in snails, thus offering new possibilities for the evaluation of schistosomiasis transmission and for schistosomiais control, as discussed.Schistosomiasis, is caused in humans by three main species of blood flukes (Schistosoma mansoni, S. haematobium, and S. japonicum) and is transmitted by freshwater snails. It continues to plague many developing countries in the tropics 1 with an estimated 200 million infected people worldwide.Freshwater snails, intermediate hosts of schistosomes, become infected by larvae (miracidia) released from schistosome eggs that reach the water with excreta. After several weeks of asexual multiplication within the snail's tissues, larvae infective to humans by active penetration through the skin (cercariae), are released into the water. Snail infection and contact patterns of humans with water infested with cercariae are important factors in the transmission of schistosomiasis, and risk of infection is normally estimated by detecting infected intermediate hosts in sites where humans come in contact with water. 2 Infection rates in field populations of snails are routinely determined by searching for cercariae shed from snails with patent infection. 3 In contrast, prepatent infections, which can constitute a significant proportion of infected snails populations, 4 are not determined routinely because of a lack of a suitable method. Microscopic examination of crushed snails in search of developing cercariae and intramolluscan-multiplying larvae (the sporocysts) 5 is sometimes used for this purpose but is highly inaccurate at early prepatency, and unsuitable for routine large-scale screening of snail populations. 4 Another approach is to examine nonshedding field snails maintained for several weeks in the laboratory for protracted shedding. However, this method is time-consuming, it cannot be done routinely on a large scale, and it can be highly inaccurate if snails mortality is high. The omission of data on prepatent infections leaves out important information for the evaluation and mathematical modeling of trans...

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Section: Discussionmentioning

confidence: 89%

mentioning

confidence: 99%

A polymerase chain reaction assay for detecting snails infected with bilharzia parasites (Schistosoma mansoni) from very early prepatency.

Hamburger¹,

He-Na²,

Xin³

et al. 1998

The American Journal of Tropical Medicine and Hygiene

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“…For examples; a PCR assay based on a highly repeated tandemly arranged DNA sequence (121 bp) detects prepatent S. mansoni infection at the 1st day post infection (80 % sensitivity) (Hamburger et al 1998). A nested PCR targeting the 18S rDNA of S. mansoni detects infection in snails 1 week post infection (100 % sensitivity) (Hanelt et al 1997). The PCR amplified sequence of the mitochondrial DNA minisatellite repeat from S. mansoni identifies infected snails 1 week post infection and with 100 % sensitivity (Jannotti-Passos et al 1997).…”

Section: Discussionmentioning

confidence: 99%

“…For examples; (1) identification of minisatellite repeat mitochondrial DNA was used to detect prepatent S. mansoni infection in B. glabrata snails (Jannotti-Passos et al 1997), (2) detection of 18S rDNA was used to detect prepatent S. mansoni infection in snails (Hanelt et al 1997) and (3) amplification of a tandem repeat sequence (121 bp) was used to detect prepatent S. mansoni infection in snails, other than PCR assays, dot hybridization using labeled probes was also used to detect infected snails (Hamburger et al 1998). …”

Section: Introductionmentioning

confidence: 99%

Molecular approach for detecting early prepatent Schistosoma mansoni infection in Biomphalaria alexandrina snail host

et al. 2014

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The present study aimed to evaluate a polymerase chain reaction (PCR) assay used for detection of Schistosoma mansoni infection in Biomphalaria alexandrina snails in early prepatent period and to compare between it and the ordinary detection methods (shedding and crushing). Biomphalaria alexandrina snails are best known for their role as intermediate hosts of S. mansoni. DNA was extracted from infected snails in addition to noninfected ''negative control'' (to optimized the efficiency of PCR reaction) and subjected to PCR using primers specific to a partial sequence of S. mansoni fructose-1,6-bus phosphate aldolase (SMALDO). SMALDO gene was detected in the infected laboratory snails with 70, 85, and 100 % positivity at the 1st, 3rd, and 7th day of infection, respectively. In contrast, the ordinary method was not sensitive enough in detection of early prepatent infection even after 7 days of infection which showed only 25 % positivity. By comparing the sensitivity of the three methods, it was found that the average sensitivity of shedding method compared to PCR was 23.8 % and the average sensitivity of crushing method compared to PCR was 46.4 % while the sensitivity of PCR was 100 %. We conclude that PCR is superior to the conventional methods and can detect positive cases that were negative when examined by shedding or crushing methods. This can help in detection of the areas and times of high transmission which in turn will be very beneficial in planning of the exact timing of the proper control strategy.

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“…These methods exhaust time and need professional staff to be performed (Hanelt et al 1997). PCR assay enabled very sensitive and early detection of infection, and the feasibility of large scale examination of snails with minimal efforts (Hamburger et al 1998;Hanelt et al 1997).…”

Section: Introductionmentioning

confidence: 99%

Digenetic larvae in Schistosome snails from El Fayoum, Egypt with detection of Schistosoma mansoni in the snail by PCR

et al. 2014

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The present study aims to detect the digenetic larvae infections in Bulinus truncatus and Biomphalaria alexandrina snails and also PCR detection of Schistosoma mansoni infection. The snails were collected from different branches of Yousef canal and their derivatives in El Fayoum Governorate. The snails were investigated for infection through induction of cercarial shedding by exposure to light and crushing of the snails. The shed cercariae were S. mansoni, Pharyngeate longifurcate type I and Pharyngeate longifurcate type II from B. alexandrina, while that found in B. truncatus were Schitosoma haematobium and Xiphidiocercaria species cercariae. The seasonal prevalence of infection was discussed. Polymerase chain reaction was used for the detection of S. mansoni in the DNA from field collected infected and non infected snails. The results of PCR showed that the pool of B. alexandrina snails which shed S. mansoni cercariae in the laboratory, gave positive reaction in the samples. Pooled samples of field collected B. alexandrina that showed negative microscopic shedding of cercariae gave negative and positive PCR in a consecutive manner. Accordingly, a latent infection in the snail (negative microscopic) could be detected by using PCR.

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Detection of Schistosoma mansoni in Biomphalaria Using Nested PCR

Cited by 47 publications

References 0 publications

A polymerase chain reaction assay for detecting snails infected with bilharzia parasites (Schistosoma mansoni) from very early prepatency.

A polymerase chain reaction assay for detecting snails infected with bilharzia parasites (Schistosoma mansoni) from very early prepatency.

Molecular approach for detecting early prepatent Schistosoma mansoni infection in Biomphalaria alexandrina snail host

Digenetic larvae in Schistosome snails from El Fayoum, Egypt with detection of Schistosoma mansoni in the snail by PCR

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