Some Observations on<i>Schistosoma Mansoni</i>in Rodents in the Transvaal

Pitchford, R. J.; Visser, P. S.

doi:10.1080/00034983.1960.11685981

Cited by 18 publications

(15 citation statements)

References 3 publications

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“…The temperature-dependent prepatent period has been studied in the semi-tropics (Pitchford & Visser, 1965), prepatent mortality by Sturrock (1966), life span by Meuleman (1972) and the effect on infection of decoy snails (Helisoma) by Frandsen (1976). In this paper the daughter sporocyst stage of the parasite development was used as the focal point to determine miracidium infectivity, variation in infections in different water volumes, snail densities and miracidium densities and then to measure the decoy effect of Bulinus truncatus and Cleopatra bulimoides snails in the B. pfeifferi/S.…”

Section: Introductionmentioning

confidence: 99%

The invasion of Biomphalaria pfeifferi by Schistosoma mansoni miracidia and the development of daughter sporocysts

Babiker

Amin

Fenwick³

1984

Hydrobiologia

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Laboratory experiments have been carried out to determine the susceptibility of Gezira Biomphalaria pfeifferi snails to S. mansoni miracidia and the relationship between miracidia and daughter sporocyst production at the 10-17 day development stage. The relationship between snail numbers, miracidia numbers and water volume has also been studied. Two non susceptible snails, Bulinus truncatus and Cleopatra bulimoides, both of which occur naturally in Gezira canals, were tested to see if they act as decoys for S. mansoni miracidia.The results showed that the B. pfeifferi are 100% susceptible to S. mansoni invasion, at least to the daughter sporocyst development stage. The more miracidia that penetrated the more daughter sporocysts were produced, however individual variation and overlap were great. When one miracidium was released to find one snail it succeeded in low water volumes (5 m, 50 ml), but failed in 5 litres. When 100 miracidia were released mortality of snails was high suggesting superinfection particularly when only one or five snails were available. Among survivors daughter sporocyst counts were very high.Cleopatra and Bulinus snails do have a decoy effect when present in large numbers. In their presence the number of infected snails was marginally reduced and the number of daughter sporocysts greatly reduced. H owever, if superinfection is reduced by decoy effect, it is conceivable that Biomphalaria may be protected by decoy snails in circumstances where miracidia counts are high.

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Section: Introductionmentioning

confidence: 99%

The invasion of Biomphalaria pfeifferi by Schistosoma mansoni miracidia and the development of daughter sporocysts

Babiker

Amin

Fenwick³

1984

Hydrobiologia

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“…This corroborates findings of Houmsou [21] in Nigeria, who reported no monthly or seasonal difference in the prevalence of infection. On the contrary, well-marked seasonal variation in Schistosoma infection was reported by several authors [16,17,[54][55][56]. The absence of seasonal difference in the occurrence in infection may suggest perennial transmission of infection noting high dependency of the population on stream water source.…”

Section: Discussionmentioning

confidence: 86%

Seasonal Pattern and Occurrence of Schistosoma haematobium Egg Excretion among Pregnant Women in Munyenge, South West Region, Cameroon

Wepnje

Anchang-Kimbi

Lehman

et al. 2019

IJTDH

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Aim: The aim of this study was to describe temperature, precipitation pattern and the occurrence of maternal urogenital schistosomiasis (UGS) in Munyenge in 2017. Study Design: It was a twelve-month cross-sectional study. Study Site and Duration: The study was carried out in Munyenge from January to December 2017. Materials and Methods: Volunteer pregnant women attending antenatal care clinic were enrolled consecutively on a monthly basis from January to December 2017. A semi-structured questionnaire was used to obtain information on socio-demographic data and water contact behaviour. Urine samples were analysed for presence of microhaematuria and/or Schistosoma haematobium ova using filtration method. Monthly land surface temperature (LST) and precipitation were sourced from MODIS and CHIRPS satellite data respectively. Statistical analyses performed were analysis of variance, student t- test and correlation analysis. Results: The mean annual temperature was 27.18 ± 0.74°C. Monthly temperatures were fairly constant (range: 26.12 to 28.82°C). Precipitation varied greatly (range: 0.26 - 12.75 mm) with a mean of 6.58 ± 4.5mm. A marginal negative correlation (r = -0.586; P = .04) was observed between stream usage and precipitation where stream usage reduced with increase in precipitation. Generally, there was high dependence on the stream as source of water (60.9 - 90.6%) in the study area. Dependency on the stream was associated (r = 0.603; P = .03) with domestic and bathing activities. The annual prevalence of maternal UGS was 24.1% (77/320) with a high occurrence during the rainy season (16.6%; 53/320) than the dry season (7.5%; 24/320) but the difference was not significant (χ2 = 2.26; P = .13). There was no significant difference between months. Conclusion: Our findings show no seasonal variation in the occurrence of maternal UGS in Munyenge. Transmission of infection may be perennial.

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“…Integrating this difference over time, therefore, we would obtain the model's prediction of the total progress of development. There are two ways to envisage this integral: (1) as an accumulation of heat, over time, or (2) as an accumulation of development time, with each time increment weighted appropriately with respect to temperature. The first interpretation led to the older label 'heat unit model' and the second to the more recent label 'physiological time model'.…”

Section: Basic Physiological-time Modelmentioning

confidence: 99%

Prediction of Schistosome Cercarial Shedding with a Physiological-Time Model

Lee

1977

Int J Epidemiol

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While making longitudinal observations on schistosome cercarial shedding, Pitchford and Visser found that there is an annual fluctuation in the minimum time for cercarial development, which is apparently related to temperature (1). Schistosome control strategy could be designed to take advantage of this fluctuation if it were predictable. Inspired by the successes of physiological time models ('heat-unit models') in predicting life-stage durations of various agricultural pests (2,3), we have developed a model of this type for the schistosomes. This model fits the data of Pitchford and Visser quite well. Coupled with recent temperature history and short term temperature forecast, it could be a useful tool for predicting the onset of cercarial shedding.

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Some Observations onSchistosoma Mansoniin Rodents in the Transvaal

Cited by 18 publications

References 3 publications

The invasion of Biomphalaria pfeifferi by Schistosoma mansoni miracidia and the development of daughter sporocysts

The invasion of Biomphalaria pfeifferi by Schistosoma mansoni miracidia and the development of daughter sporocysts

Seasonal Pattern and Occurrence of Schistosoma haematobium Egg Excretion among Pregnant Women in Munyenge, South West Region, Cameroon

Prediction of Schistosome Cercarial Shedding with a Physiological-Time Model

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