There is an entire absence of inflammation about this ringworm thus differentiating it from the more common tropical ringworms. Again the axillae and crotch are much more rarely affected than in other ringworms as is also true of the face, palms of hands and soles of feet. The scalp is never affected.
Some claim that the fungus never invades the nails but Manson states that this frequently occurs. The presence of the fungus in a scale treated with 10% solution of sodium hydrate differentiates the scales from those of ichthyosis.
Tinea intersecta is somewhat similar to tinea imbricata when first appearing, showing dark brown patches but it never shows the concentric rings. The ordinary ringworms present inflammatory characteristics.
Treatment
A thorough preliminary scrubbing with soap and water in order better to expose the fungus to curative applications is important.
For treatment Manson recommends iodine liniment. This contains 12½% of iodine as against 7% for the tincture. The liniment has also 3½% of glycerine which is not an ingredient of the tincture. Both tincture and liniment have 5% of potassium iodide. The application of the tincture does not seem to be as satisfactory as the liniment, the stronger preparation being more effective.
Chrysarobin is very effective but very irritant and has to be used with care. An application of a 5% solution of chrysarobin in chloroform to the affected area, then painting it over with a 50% aqueous solution of ichthyol, often gives good results.
Some prefer a 2% to 5% ointment of chrysarobin. Chrysarobin produces a conjunctivitis if used near the eyes. Again if absorbed it may act as a renal irritant.
Castellani strongly recommends the use of resorcin in tincture of benzoin (60 to 120 grains of resorcin in 1 ounce of tincture of benzoin). Either remedy alone has very little effect, the combination being necessary. The application is made once or twice daily. In addition to this treatment the patient should be scrubbed with sand-soap and hot water twice a week.
As regards prophylaxis the clothing should be boiled. The natives attach value in preventing the disease to anointing the body with cocoanut oil.