MOLECULAR DIAGNOSIS OF LEPTOSPIROSIS AND DETECTION OF LEPTOSPIRA SEROVARS PREVALENT IN DOMESTIC ANIMALS IN WAYANAD DISTRICT
Loading...
Date
2018-12-10
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
COLLEGE OF VETERINARY AND ANIMAL SCIENCES, POOKODE WAYANAD
Abstract
Leptospirosis has re-emerged as a prominent zoonotic disease of global
distribution especially in developing countries causing severe complications in human
beings and animals. Accurate identification of infecting serovars is necessary for
adopting effective vaccines, as the immunity is serovar specific. Southern states like
Kerala and Tamil Nadu is found to be endemic for leptospirosis. In districts like Wayanad
of Kerala, conditions are congenial for occurrence of leptospires in environment as well
as natural carriers. Chances of endemicity also are greater due to several factors including
heavy rainfall, water holding soil, sharing of natural water resources by man and animals,
and large number of rodents and stray dogs. Though many studies have identified the
prevalent Leptospira serovars in many districts in Kerala, no study has been carried out
in diagnosis and detection of prevalent serovars in Wayanad. . This scenario demanded
for identification of prevalent serovars and detection of presence of infection in domestic
animals in Wayanad. Hence, the present study was undertaken with the objective of
detecting infection by PCR and identification of prevalent serovars by MAT.
A total of 71 samples were collected from dogs, cattle and rats from Wayanad
districts. Out of 71 samples, 25 samples were collected from animals suspecting
leptospirosis brought to Teaching Veterinary Clinical Complex, Pookode. Six post
mortem samples of dogs suspecting leptospirosis were collected from Department of
Veterinary Pathology, College of Veterinary and Animal Sciences, Pookode. Four rat
tissue samples were collected from rats captured from campus of College of Veterinary
and Animal Sciences, Pookode. Thirty six serum samples were collected from different
regions of Wayanad.
All the samples collected were subjected to total DNA extraction and PCR was
carried out using G1/G2 and lipL32 based primers. The test could detect amplicons in
positive control but no positive results were yielded by clinical samples.
For detection of prevalent serovars, MAT was conducted for 61 samples with
12 reference serovars. Twenty serum samples were found to be positive at 1: 200 serum
dilution. Predominant serovar showed agglutination was Pyrogenes (7 samples),
followed by Grippotyphosa (6 samples), and then Bataviae (3 samples),
Icterohaemorrhageae (3 samples), Javanica (3 samples), Pomona (3 samples), Australis
(2 samples), Canicola (2 samples). Out of 20 positive samples, nine samples have shown
54
agglutination with more than one serovar. In such cases, serovar with highest MAT titre
was considered as infecting serovar. Mixed infections included Pyrogenes and Bataviae
(3 samples), Pyrogenes and Javanica (2 samples), Grippotyphosa and Canicola (2
samples), Pyrogenes and Australis (1 sample), Grippotyphosa and Javanica (1 sample).
The MAT titre of agglutinating serovars varied from 1:3200 to 1: 200. Highest MAT titre
was 1:3200 against serovar Pyrogenes.
Previously reported prevalent serovars in other parts of Kerala included
Australis, Autumnalis, Pomona, Canicola etc. Though these serovars were reported in
present study also, the predominant serovar revealed was Pyrogenes. Similarly, serovars
present in mixed infections were also slightly different from those present in other parts
of Kerala. As the serological data acquired from this study is novel and distinct, more
detailed studies including more number of samples is required for confirmation of
prevalent serovars in Wayanad district.