Page:Tropical Diseases.djvu/809

XLI] sandal- wood oil, salol, benzoic acid, and so forth. Stone, and troublesome new growths, are to be removed by operation. Where distress was extreme, Mackie and others have had good results from perineal cystotomy and drainage. Adenomatous growths in the rectum, where accessible, should be removed. In severe rectal disease, milder measures failing, excision of the affected part of the gut may be necessary. Perineal fistula must be dealt with on ordinary surgical principles. Hyperplasia in the vagina and cervix is best treated by scraping. Provided reinfection be avoided by the exercise of prudence in the matter of water, there is no necessity for sending the patient with schistosomurn disease away from the country in which the parasite was acquired.

Prevention.— In the endemic districts, children, in particular, should be carefully and repeatedly warned against drinking or bathing in rivers, ponds, and canals. Seeing that the larva of schistosomum, on obtaining access to fresh water, enters a fresh-water mollusc and, after undergoing developmental changes, obtains access to the human host, it is evident that if the larva be kept from getting into the water, or if drinking-water be boiled or filtered,the spread of the disease from man to man would be effectually prevented; therefore every care should be exercised to prevent the diffusion of the disease, by prohibiting the evacuation of excreta into water where the miracidia might find the opportunity of development and transmission. This prohibition should not be restricted to patients exhibiting definite symptoms of the disease, but extended to all, because, as special inquiries have shown, a large proportion of the infected do not suffer from any troublesome symptom, and are often unaware of the infection. Leiper points out that much might be accomplished by attacking the mollusc intermediary and the free cercaria. As regards the former, he suggests periodic drying of irrigation canals and the use of chemical manures; as regards the latter, the use of cercariacides such as sulphate-of-soda tablets or chlorine (1-500,000) for