Under experimental investigation

Used for diagnosis but requires further evaluation for routine use
Generally accepted useful routine diagnostic test

41

Complement
Fixation

Precipitin

Agglutination

Methylene Blue

Dye Test

(3)

vials placed in a metal case with a screw
cap and enclosed in a cardboard container
with a metal screw cap are satisfactory.
To prevent breakage, pack the vials in
paper or cotton and to prevent leakage,
seal them with adhesive tape around the
top. Mailed specimens require use of a
preservative and a two-vial method of
collection and shipping is advocated.
One vial contains 5 or 10% formalin, the
other PVA fixative. If the delay in
transit will not exceed 24 hours, an
empty vial should replace the one with
formalin. Thus the laboratory has a formal-
inized or unpreserved specimen that can be
examined for cysts and helminth eggs and
a PVA-fixed specimen that can be examined
for trophozoites, and to a lesser degree,
for cysts. The method of handling a stool
specimen for parasitological examination is
shown in Figures 2 and 3.

Cysts of

Due to intermittent passing of parasites from
the host, examination of multiple specimens
is desirable. Ascaris, hookworm, and Trichuris
eggs appear almost daily in feces.
Entamoeba histolytica appear irregularly in
the stool and the production of certain of
the helminth infections such as schistosomes and
Diphyllobothrium latum is also unreliable. This
emphasizes the need for collection of several
specimens spread over 10 to 14 days.

Normally passed stool specimens, spaced several days apart, are preferable to specimens obtained by catharsis or sigmoidoscopy, since cysts will more likely be present.

Purged

Figure 2. PVA-FIXATIVE TECHNIQUE

FOR SUBMITTING STOOL SPECIMENS TO BE EXAMINED FOR PARASITES

specimens increase the possibility of find-
ing organisms. A cathartic of sodium sulphate
or buffered phospho-soda is preferable to
magnesium sulphate since the morphology of
the organism is less affected. Collect each
bowel movement separately, number them
serially, and deliver promptly to the labora-
tory. Eggs, larvae, cysts, and trophozoites
may be found in such specimens. If there will
be delay before the specimen is examined, add
a portion to PVA fixative.

(4) Collection of specimens by sigmoidoscopy

(5)

In amebiasis if stools are negative material
may be obtained by sigmoidoscopy immediately
following a normal bowel movement or if a
cathartic is given, after a lapse of 2 to 3
hours. Collect the specimens with a serologic
pipette rather than a cotton swab, by aspirat-
ing material from any visible lesion and the
mucosa. Pathologic areas or the mucosa wall
may also be gently curetted or scraped. Exami-
nation of sigmoidoscopic specimens for diagnosis
of amebiasis must be immediate but after the
direct examination, PVA fixative may be added
and the preparation dried and stained.

Collection of specimens other than feces

Urine

Sputum specimens as well as stools should be
collected in suspected cases of paragonimiasis.
Pulmonary amebiasis and echinococcosis may
also be detected by sputum examination.
specimens are utilized in diagnosis of
Trichomonas vaginalis and Schistosoma
haematobium. The optimum urine specimen to
be examined for the latter is one passed at
or shortly after noon. Vaginal swabs or scrap-
ings are used in diagnosis of T. vaginalis.
Anal swabs or cellulose tape specimens are
the usual means of collecting the eggs of
Enterobius vermicularis, as shown in Figure 4.
Specimens taken between 10:00 and 12:00 mid-
night, or in the early morning before defeca-
tion, are best. Three consecutive examina -
tions are desirable and a short delay in
examination of either the swab or tape specimen
makes no particular difference, but the specimens
should be refrigerated if examination is delayed
for more than a day.