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Original ArticleOpen Access
Prevalence of Antibodies to Leptospira Serovars in Rodents and Shrews Trapped in Low and High Endemic Areas in Thailand
Kositanont U 
,
Naigowit P ,
Jmvithaya A ,
Singchai C ,
P
,
Naigowit P ,
Jmvithaya A ,
Singchai C ,
P PIMJAI NAIGOWIT, BSc, MT (ASCP)**,
CHANTRA SINGCHAI, DVM***,
Objective
: To investigate the prevalence of antibodies to
Leptospira
serovars in rodents
and shrews trapped in urban and rural areas in low and high endemic areas in Thailand.
Material and Method
: A total of 1 ,664 serum samples were collected from rodents and
shrews in areas of low and high endemicity for leptospirosis. Four areas classified by case rates (CR)
per I 00,000 population of leptospirosis were urban Area
I
Bangkok (CR
=
0.07), rural Area II (CR
=
0.24), rural Area III (CR
=
1.97) and rural Area IV (CR
=
48.20). All serum samples were investigated
for antibodies to leptospires by microscopic agglutination test (MAT) using antigens from each of the
22 pathogenic serovars of
Leptospira interrrogans
: australis, autumnalis, ballum, bangkok, bataviae,
bratislava, canicola, celledoni, copenhageni, djasiman, grippotyphosa, hardjo, hebdomadis, ictero-
haemorrhagiae, javanica, pomona, pyrogenes, rachmati, saigon, sejroe, tarassovi and wolffi and one
non-pathogenic strain of
L.
bijlexa
serovar patoc.
Results
: Ninety-four (5.6%) serum samples were positive for
Leptospira
antibodies. The
most commonly detected antibodies were to serovars pyrogenes (39.1%), sejroe (19.1%), bataviae
(10.0%), pomona (6.4%), autumnalis (5.5%), copenhageni (3.6%) and javanica (3.6%). The positive
rates in Area I, II, III and IV were 7.6 per cent, 2.9 per cent, 4.6 per cent and 7 .I per cent, respec-
tively. The seroprevalence in rural areas tended to increase significantly with high endemicity for
leptospirosis (Chi-square for trend, p
=
0.04). The seropositive rates by animal species were 39/496
(7.9%), 22/322 (6.8%), 23/492 (4.7%), 6/170 (3.5%), 41175 (2.3%), 0/4 (0%) and 0/5 (0%) in
Rattus
norvegicus, Rattus exulans, Rattus rattus, Bandicota indica, Bandicota savilei, Mus musculus
and
Suncus murinus,
respectively. There was a statistical trend between seropositive rates in
R. exulans
and endemicity for leptospirosis (Chi-square for trend, p
=
0.04).
Vol. 86 No.2
PREVALENCE OF
LEPTOSPIRAL
ANTIBODIES IN RODENTS IN THAILAND
137
Conclusion : The 5.6 per cent of rodents and shrews trapped in urban and rural areas in
Thailand were reservoirs of leptospires. The results of high seroprevalence in rats also indicate the
high endemicity for leptospirosis.
Key word : Leptospirosis, Seroprevalence, Rodents, Low and High Endemic Areas
CHANTRA SINGCHAI, DVM***,
Objective
: To investigate the prevalence of antibodies to
Leptospira
serovars in rodents
and shrews trapped in urban and rural areas in low and high endemic areas in Thailand.
Material and Method
: A total of 1 ,664 serum samples were collected from rodents and
shrews in areas of low and high endemicity for leptospirosis. Four areas classified by case rates (CR)
per I 00,000 population of leptospirosis were urban Area
I
Bangkok (CR
=
0.07), rural Area II (CR
=
0.24), rural Area III (CR
=
1.97) and rural Area IV (CR
=
48.20). All serum samples were investigated
for antibodies to leptospires by microscopic agglutination test (MAT) using antigens from each of the
22 pathogenic serovars of
Leptospira interrrogans
: australis, autumnalis, ballum, bangkok, bataviae,
bratislava, canicola, celledoni, copenhageni, djasiman, grippotyphosa, hardjo, hebdomadis, ictero-
haemorrhagiae, javanica, pomona, pyrogenes, rachmati, saigon, sejroe, tarassovi and wolffi and one
non-pathogenic strain of
L.
bijlexa
serovar patoc.
Results
: Ninety-four (5.6%) serum samples were positive for
Leptospira
antibodies. The
most commonly detected antibodies were to serovars pyrogenes (39.1%), sejroe (19.1%), bataviae
(10.0%), pomona (6.4%), autumnalis (5.5%), copenhageni (3.6%) and javanica (3.6%). The positive
rates in Area I, II, III and IV were 7.6 per cent, 2.9 per cent, 4.6 per cent and 7 .I per cent, respec-
tively. The seroprevalence in rural areas tended to increase significantly with high endemicity for
leptospirosis (Chi-square for trend, p
=
0.04). The seropositive rates by animal species were 39/496
(7.9%), 22/322 (6.8%), 23/492 (4.7%), 6/170 (3.5%), 41175 (2.3%), 0/4 (0%) and 0/5 (0%) in
Rattus
norvegicus, Rattus exulans, Rattus rattus, Bandicota indica, Bandicota savilei, Mus musculus
and
Suncus murinus,
respectively. There was a statistical trend between seropositive rates in
R. exulans
and endemicity for leptospirosis (Chi-square for trend, p
=
0.04).
Vol. 86 No.2
PREVALENCE OF
LEPTOSPIRAL
ANTIBODIES IN RODENTS IN THAILAND
137
Conclusion : The 5.6 per cent of rodents and shrews trapped in urban and rural areas in
Thailand were reservoirs of leptospires. The results of high seroprevalence in rats also indicate the
high endemicity for leptospirosis.
Key word : Leptospirosis, Seroprevalence, Rodents, Low and High Endemic Areas
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