A comparison of the iodine and fluorescent antibody methods for staining trachoma inclusions in the conjunctiva

Abstract

SUMMARYIn terms of the rate of positive diagnoses the indirect fluorescent antibody (FA) test was rather more effective than iodine for demonstrating trachoma (TRIC) inclusions in conjunctival scrapings, but the degree of advantage was not statistically significant. In duplicate scrapings stained at random by one or the other method, FA staining yielded the higher inclusion count significantly more often than did iodine. Some inclusions that failed to stain with FA were found on subsequent staining with Giemsa. A method is described for improving the post-FA Giemsa staining of conjunctival smears stored at subzero temperatures. Given adequate facilities, the FA stain is preferable to iodine for demonstrating TRIC inclusions in the conjunctiva; but the iodine method, properly used, holds advantages for field use.

The serum and conjunctival antibody response to trachoma in Gambian children

“…The fast-killing variant MRC-4f used in these experiments stained well with unabsorbed sera directed against serotypes 1, lb and 2 and with anti-type 2 serum absorbed with type 1 antigen; but not at all with low dilutions ( < 1/3) of anti-type 1 or lb sera cross-absorbed respectively with type lb and 1 antigens. This variant thus types like its parent strain as type 2 (Sowa et al 1971) but reacts with unabsorbed antisera to types 1 and lb.…”

“…After preliminary work on immunofluorescence methods, a group of 99 infants was selected in Salekini, a large Gambian village with 3500 inhabitants (Sowa, Sowa, Collier & Blyth, 1969;Sowa et al 1971). Thirty-seven of these children had normal (N) eyes (Table 1); the remainder had early active trachoma with or without corneal lesions, or minor conjunctival abnormalities not suggestive of TRIC infection (Ab).…”

“…Conjunctival scrapings were taken in duplicate and stained at random either with iodine or by an indirect fluorescent antibody (FA) method (Sowa et al 1971). For the purpose of the present investigation, the result was taken as positive if inclusions were found by either method.…”

“…Cover-slips were treated with dilutions of CS or blood sera, washed in PBS, and then stained with the appropriate dilution of anti-IgG or anti-IgA conjugate. Incubation and washing procedures were as described for yolk sac slide antigens (Sowa et al 1971), except that counterstaining with Evans's blue was omitted. For microscopy, the cover-slips were mounted cell-side down on fresh slides in glycerol-PBS, 9: 1.…”

“…In addition, the opportunity was taken to compare the merits of the immunofluorescence and iodine techniques for detecting conjunctival inclusions; this study has already been reported (Sowa, Collier & Sowa, 1971).…”