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การตรวจหาแอนติบอดีย์ต่อเชื้อเลปโตสไปโรซีสโดยวิธี
ELISA Test
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Lepto Latex Test
Latex Agglutination for Leptospirosis test
Introduction
Lepto Latex Test is a simple
serodiagnostic method for leptospirosis by using the latex agglutination
test to detect antibodies to leptospires.
Leptospirosis is a typical zoonosis
that can be transmitted from animals to humans and occurs worldwide.
Leptospirosis is a bacterial disease that affects humans and animals. It
is caused by bacteria of the genus Leptospira. In humans it causes a wide
range of symptoms, and some infected persons may have no symptoms at all.
Symptoms of leptospirosis include high fever, severe headache, chills,
muscle aches, and vomiting, and may include jaundice (yellow skin and eyes),
red eyes, abdominal pain, diarrhea, or a rash. If the disease is not
treated, the patient could develop kidney damage, meningitis (inflammation
of the membrane around the brain and spinal cord), liver failure, and
respiratory distress. In rare cases death occurs. Many of these symptoms
can be mistaken for other diseases. Leptospirosis is confirmed by
laboratory testing of a blood or urine sample.
The cause of infection is
Leptospira interrogans. More than 200 serovars
are know. The symptoms and signs of uncomplicated illness are similar to
those of other acute febrile illness.
Leptospirosis occurs worldwide but
is most common in temperate or tropical climates. It is an occupational
hazard for many people who work outdoors or with animals, for example,
farmers, sewer workers, veterinarians, fish workers, dairy farmers, or
military personnel. It is a recreational hazard for campers or those who
participate in outdoor sports in contaminated areas and has been
associated with swimming, wading, and whitewater rafting in contaminated
lakes and rivers. The incidence is also increasing among urban children.
The diagnosis of leptospirosis is
usually made by serological tests. Microscopic agglutination test (MAT) is
the standard test to detect serovar
specific antibodies. However, this method cannot be performed in general
laboratories because it requires cultures of reference leptospire strains
of
many serovars as a series of antigens for testing. The method is also
complicated, time consuming and need skilled for operation.
Lepto latex test : Latex
agglutination test (LA), Leptospira interrogans serovar pyrogenes was
cultured in neopeptone medium. Leptospiral cells was inactivated (killed)
with 0.1% formalin for 2 hours. The antigen-coated latex was stable for at
least 12 month when kept at 4-10 บC.
Latex agglutination was performed
as follows. One drop of antigen-coated latex particles was added to each
drop of serum samples on a glass slide and mixed thoroughly with a wooden
applicator stick. When clumping or
agglutination waas observed, within 2-5 minutes, the reaction was read as
positive.
The diagnosis of Leptospirosis by latex agglutination is convenient,
simple and rapid does not need sophisticated laboratory equipment. This
method is suitable for use as a laboratory screening test. In the present
study, LA is highly sensitive at 94.7% and specific 93.3% (of the patients
confirmed as cases of leptospirosis by Microscopic agglutination test MAT)
Principle
The Lepto Latex Test
kit is intended to use for detection of anti-Leptospires in the human
serum or plasma which capable to react with antigen of Leptospires sp.
that coated on Latex bead. The reaction of antigen and antibodies will
form agglutination clearly within 5 minutes by normal eye vision.
When no specific antibodies are
present, the latex suspension will remain homogeneous (negative result).
The broadly reactive antigen that is prepared from a killed pathogenic
strain, allows the detection of Leptospira infections caused by a wide
range of strains of different serovars. The detailed procedure is
described in the detailed protocol.
Composition of the kit :
1. Lepto Latex Test 25 test
2. Positive Control 1 bottle
3. Negative Control 1 bottle
4. Mixing Stick 25 pcs.
5. Slide Card 1 pcs.
6. Pipett dropper 25 pcs.
7. Package insert 1 pcs.
| Method |
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1.Drop
Lepto Latex Test on the
glass slide 1drop (~20 ul.) |
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2.
Then add 1 drop (20ul) of test
serum or plasma |
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3.
Mixed with a mixing stick and swirl
gently ( 100 rpm/minute)
4. Put the glass slide on the black
background. Observe the result
within 2-5 minutes. |
Interpretation :
The Positive result will be the one
that form agglutination within 2-5 minutes by eye observation. This can be
compare with the positive
control while the negative result will show no agglutination of the latex
bead as perform with negative control.
The Lepto Latex Test has been
evaluated in a laboratory based study on serum samples collected from
laboratory confirmed leptospirosis case patients and controls in different
parts of the world. The assay also has been evaluated in a hospital based
study in India. The sensitivity and specificity of the assay equals those
of the MAT performed with a panel of antigens. The main advantages of the
assay are that the result is obtained very quickly and that the cards
containing the dried reagent are individually wrapped and are highly
stable; the assay remains fully active when cards are stored for 2 years
at temperatures up to 45?C.
Related publications
Smits, H.L., M.A.W.G. van der Hoorn,
M.G.A. Goris, G.C. Gussenhoven, C. Yersin, D.M. Sasaki, W.J. Terpstra, and
R.A. Hartskeerl. (2000) A simple latex agglutination assay for the rapid
serodiagnosis of human leptospirosis J. Clin. Microbiol. 38;1272-1275.
Smits, H.L. H.D. Chee, C.K. Eapen,
M. Kuriakose, S. Sugathan, M.Hussein Gasem, C. Yersin, D.M. Sasaki, R.F.M.
Lai A Fat, R.A. Hartskeerl, B. Liesdek, T.H. Abdoel, M.G.A. Goris and G.C.
Gussenhoven. (2001) Latex based, rapid and easy assay for human
leptospirosis in a single test format. Trop. Med. & Int. Health (accepted
for publication).
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