Identification of Dermatophilus congolensis from lower leg dermatitis of cattle in Kerala, India.

This study was conducted to identify the aetiological agents associated with a particular type of lower leg dermatitis, locally called pododermatitis, among dairy cattle in Kerala. Skin scabs and scrapings were collected aseptically from 82 naturally occurring cases of lower leg dermatitis in cattle and were subjected to direct microscopical examination and bacterial and fungal culture. Microscopical examination of the skin scrapings with 10% potassium hydroxide revealed fungal spores in hair shafts from only two samples and did not reveal the presence of mites or other parasites. Fungal culture yielded dermatophytes from only five samples; these were identified as Trichophyton mentagrophytes in two cases, T verrucosum in one case, Epidermophyton floccosum in one case and Microsporum nanum in one case. Microscopical examination of Giemsa- and Gram-stained smears of the scab material from the lesions from 72 cases revealed characteristic Gram-positive septate branching filaments with multiple rows of spherical to ovoid cocci, with a typical 'tram-track' appearance suggestive of Dermatophilus congolensis. Culture of the scab materials on sheep blood agar in the presence of 10% carbon dioxide yielded typical beta haemolytic colonies of D. congolensis from 75 samples. The isolates were further confirmed by the macroscopic and microscopic morphology of the colonies, and biochemical test results. This study confirmed the presence of dermatophilosis caused by D. congolensis in cattle in Kerala.

Bovine carriers of Anaplasma marginale and Anaplasma bovis in South India.

Carriers of bovine anaplasmosis in Northern Kerala, South India were detected using conventional microscopical and molecular techniques. PCR-RFLP and nested PCR techniques were used for detection of Anaplasma marginale and Anaplasma bovis respectively and the PCR products were confirmed by sequencing. Out of 150 samples tested, 25 were detected positive for A. marginale and five for A. bovis based on molecular tests. The inclusion bodies of A. marginale could be detected by microscopy in two blood smears after staining by giemsa while acridine orange staining detected three smears positive. The data clearly suggest the higher sensitivity of molecular techniques for diagnosis of these diseases.

Bovine carriers of Anaplasma marginale and Anaplasma bovis in South India

Carriers of bovine anaplasmosis in Northern Kerala, South India were detected using conventional microscopical and molecular techniques. PCR-RFLP and nested PCR techniques were used for detection of Anaplasma marginale and Anaplasma bovis respectively and the PCR products were confirmed by sequencing. Out of 150 samples tested, 25 were detected positive for A. marginale and five for A. bovis based on molecular tests. The inclusion bodies of A. marginale could be detected by microscopy in two blood smears after staining by giemsa while acridine orange staining detected three smears positive. The data clearly suggest the higher sensitivity of molecular techniques for diagnosis of these diseases.

Haemoprotozoa of cattle in Northern Kerala, India.

A cross-sectional study was conducted using 150 blood samples collected from apparently normal / healthy crossbred cattle of Northern Kerala, South India, for detection of haemoprotozoan infections using staining techniques (Giemsa and Acridine Orange) and specific PCR. Theileria like piroplasms and Babesia bigemina were the only protozoan organisms detected in blood smears. Polymerase chain reaction using specific primers revealed amplification of products specific for Trypanosoma evansi (34.6%), Theileria sp. other than T. annulata (16%) and B. bigemina (0.6%). The higher prevalence rate of Trypanosoma evansi indicated that the subclinical parasitism can be due to higher prevalence of tabanid flies. The study also revealed the presence of a theilerial piroplasm other than T. annulata in North Kerala, which needs further investigation.

Immune response in goats to two commercial foot-and-mouth disease vaccines and the assessment of maternal immunity in their kids.

In this investigation, the immune response of goats to two commercial foot-and-mouth disease vaccines (FMDV) was compared. Highest mean antibody titre was observed on days 60 and 21 in goats vaccinated with two doses of algel (group 1) and oil adjuvant (group 2) quadrivalent vaccines, respectively. There was no significant (P > 0.05) difference in mean antibody titre between the two vaccine groups. However, the antibody titres for type O fell below the protective titres by day 180 and 270 for groups 1 and 2, respectively. The mean maternal antibody titre was 0.610 +/- 0.0 immediately after birth. The highest mean maternal antibody titre was observed at 24 h after birth for all serotypes and then steadily declined. The maternal immunity of kids born to the vaccinated does was persistent up to 90 days after birth. There was no significant (P > 0.05) difference in mean maternal antibody titre between the two groups of goats for all four serotypes throughout the study period. The protective maternal antibody titre for serotype O was maintained only up to 1 week after birth, where for the other three serotypes A, C and Asia1 the protective maternal antibody titre was maintained up to 4 weeks of birth. Oil adjuvant vaccine may be used for control of FMDV in goats and the animals have to be revaccinated after 9 months, whereas the kids must be vaccinated at around 3-4 months after birth. Goats must be included in the FMDV control programmes and the same schedule for cattle can be followed.

Molecular epidemiology of rabies virus isolates in India.

In India, rabies is enzootic and is a serious public health and economic problem. India has a large population of stray dogs which, together with a lack of effective control strategies, might have led to the persistence of rabies virus (RV) in the canine population. Our objective was to study the molecular epidemiology of RV isolates in India based on nucleotide sequence analysis of 29 RV isolates originating from different species of animals in four states. Here we have analyzed two sets of sequence data based upon a 132-nucleotide region of the cytoplasmic domain (CD) of the G gene (G-CD) and a 549-nucleotide region (Psi-L) that combines the noncoding G-L intergenic region (Psi) and a fragment of the polymerase gene (L). Phylogenetic analysis revealed that the RV isolates belong to genotype 1 and that they were related geographically but were not related according to host species. Five different genetic clusters distributed among three geographical regions were identified. Comparison of the deduced amino acid sequences of G-CD between RV isolates revealed three amino acid changes (amino acid 462G [aa462G], aa465H, and aa468K) that distinguished the Indian RVs from RV isolates in other parts of the world. Analysis of the data indicated that the dog rabies virus variants are the major circulating viruses in India that transmit the disease to other domestic animals and humans as well.