@article {15441, title = {Effects of water treatment processes on schistosome cercariae}, journal = {Bulletin of National Institute of Health Sciences}, volume = {2}, number = {189}, year = {1947}, note = {Journal Article
Not Available}, pages = {109-30}, abstract = {

Various laboratory tests were carried out with regard to the effects, on cercariae of S. japonicum and S. mansoni, of the water treatment processes (1) clarification, (2) filtration and (3) chlorination.

(1) The effect of coagulation with alum and soda ash on cercariae of S. japonicum was tested in a variety of concentrations and it was concluded that the addition of as much as 32 grains of ammonium alum per gallon, with appropriate amounts of soda ash, was inadequate against the cercariae. This amount of alum is in excess of that used in municipal water plants.

(2) The effect of filtration through Seitz-type filter pads was tested on cercariae of S. mansoni. With the use of heavy concentrations of cercariae in three experiments, none was recovered in any of the effluents.

(3) The following chlorine compounds were tested: High test calcium hypochlorite (HTH powder); chloramine solutions, formed by adding HTH powder to water containing the ammonium ion; Halazone tablets; and succinchlorimide.

The results of all these tests, in which both S. mansoni and S. japonicum cercariae were generally used, are described in detail and cannot satisfactorily be summarized. In general, the cercaricidal value of the chlorine compounds used was favourably reported upon.

In addition to chlorine compounds, two iodine-containing compounds were tested; namely, potassium permanganate/iodide/iodate-citric acid tablets and \" Bursoline \" tablets. The former compound, when used at the prescribed dose of one tablet per litre of water, killed cercariae in 5 minutes or less. In testing the compound \" Bursoline \", particular attention was given to the type of water used in the experiment, e.g., filtered river water; unaltered river water; water to which leaf infusions had been added; water from an aquarium in which Bulinus snails had been kept. This compound was effective at a rate of one tablet per litre in clear water but its action diminished in water having increased organic content. It is remarked that this factor might also affect the cercaricidal value of chlorine compounds.

Miscellaneous cercaricidal tests were carried out with several other chemical agents; a germicidal rinse, Mikroklene; the surface active agents Aerosol OT, Nacconol, and Roccal; copper sulfate; and a DDT emulsion.

Mikroklene.-In a concentration of 1 gm. per litre, all cercariae were killed in 3 to 5 minutes. The presence of organic matter appeared to have little influence on its action.

Nacconol (alkyl-aryl sodium sulphonate).-Killed cercariae in 3 minutes in a concentration of 0.4 gm. per litre (active Nacconol) and within 10 minutes at 0.02 gm. per litre. At 0.01 gm. per litre (10 p.p.m), cercariae were killed within 25 minutes.

Roccal (alkyl dimethyl ammonium chloride).-In the higher concentrations, 1: 5, 000 and 1: 10, 000, cercariae were killed in 5 minutes. At 1: 100, 000 (10 p.p.m), all were dead within 30 minutes in filtered river water at 30\° to 31 \°C. It is concluded that Roccal is an effective cercaricide, especially with alkaline waters such as S. mansoni cercariae would occur in naturally.

Aerosol OT (dioctyl sodium sulphosuccinate).-The tests showed that only in relatively concentrated solutions was this compound effective but that in nonlethal concentrations it might enhance or accelerate the effects of other cercaricides.

Copper sulphate-Tested in concentrations of 5, 10 and 50 p.p.m, it proved effective only at 50 p.p.m, or more. It could not be relied upon at 5 or 10 p.p.m to kill cercariae within a reasonable time.

DDT in emulsion with Triton and xylene.-In limited tests this proved to be not an effective cercaricide in concentrations of 0.05 and 0.1 p.p.m, but at 10 p.p.m killed cercariae within 75 minutes

}, keywords = {*Cercaria, *Heterophyidae, *Schistosoma, *Schistosomatidae, *Schistosomiasis, *Trematode Infections, *Water Purification, Animals}, author = {Jones, M. F. and Brady, F. J.} }