Unveiling genotypic diversity of Theileria orientalis in lethal outbreaks among bovines in Karnataka, India.

Theileria orientalis, the causal agent of oriental theileriosis, is known to cause mild disease in cattle and buffalo across the world. Recently, different genotypes of T. orientalis have emerged as pathogenic, causing high reported morbidity in cattle. This study focuses on investigating three suspected outbreaks of oriental theileriosis that resulted in fatalities among crossbred and indigenous bulls in Karnataka, India. Examination of blood smears revealed the presence of T. orientalis piroplasms within erythrocytes. The genetic characterization of T. orientalis was conducted by targeting specific markers, including the mpsp gene, p23 gene, and ribosomal DNA markers (18S rRNA gene, ITS-1, and ITS-2). Analysis based on the 18S rRNA gene unveiled the presence of both Type A and Type E genotypes of T. orientalis in the outbreaks. The mpsp gene-based analysis identified genotype 7 of T. orientalis in crossbred cows, whereas genotype 1 (Chitose B) was found to be present in indigenous bulls. Haplotype network analysis based on the mpsp gene revealed the presence of 39 distinct haplotypes within the 12 defined genotypes of T. orientalis with a high haplotype diversity of 0.9545 ± 0.017. Hematological and biochemical analysis revealed a decrease in calcium, hemoglobin levels, red blood cell counts, and phosphorus. This study constitutes the initial documentation of a clinical outbreak of oriental theileriosis in indigenous bulls with genotype 1 (Chitose 1B). Substantial epidemiological investigations are imperative to gain a comprehensive understanding of the geographical distribution of distinct genotypes and the diverse clinical manifestations of the disease across various hosts.

Dairy cattle and buffaloes harbouring gastrointestinal parasites in various zones and climatic regions established by scientometrics.

The prevalence of gastrointestinal parasites (GIP) in cattle and buffaloes from different zones and climatic regions in India was determined by scientometrics. The GIP prevalence studies (64) described during 2004-2021 were retrieved from online databases, and offline literature and meta-analyses were conducted by meta package in R-Software. The GIP prevalence in India was 47% (95% level CI 41-54%, PI 12-85%) in cattle, 42% (95% level CI 35-50%, PI 9-84%) in buffaloes and 45% (95% level CI 40-51%, PI 12-84%) in cattle and buffaloes obtained from 40,884, 27,624 and 74,579 samples, respectively. The GIP prevalence was higher in the South zone (60%) for cattle, North zone (52%) for both buffaloes, and cattle and buffaloes. A higher GIP prevalence was observed in Tamil Nadu for cattle, Chhattisgarh and Tamil Nadu for buffaloes, and Karnataka for cattle and buffaloes. Prevalence of Ostertagia spp. in cattle, Buxtonella spp. in buffaloes, and Haemonchus spp. in cattle and buffaloes were higher among parasitic species. The polar and Semi-Arid Steppe climatic region harbours more GIP than other regions. Thus, the higher prevalence zones, states, sample types, parasite classes, parasitic species, and climatic regions identified in the present study may be used by policymakers for making informed decisions and effectively using scarce resources. However, there is a need to prevent GIP infections by implementing scientific managemental practices in dairy farms, rotational use of anthelmintic drugs, appropriate control, and preventive measures, which will result in beneficial dairy farming in India.

Analysis of Genetic Diversity of cytb gene from Babesia gibsoni Isolates from Naturally Infected Dogs in Karnataka, India.

PURPOSE: The study aimed to investigate genetic diversity in Babesia gibsoni, the causative agent of canine babesiosis, and to assess the presence of atovaquone-resistant isolates in naturally infected dogs. METHODS: A total of 24 blood samples confirmed for B. gibsoni infection was subjected to PCR amplification and sequencing based on cytb gene. Genetic characterization of B. gibsoni as well as attempts to detect the point mutation rendering atovaquone resistance was carried out based on the analysis of nucleotide sequence of cytb gene using bioinformatics software. RESULTS: The findings indicated that the B. gibsoni isolates in the investigation exhibited a high nucleotide identity with the Asian genotype, ranging from 98.41 to 98.69%. Notably, none of the isolates carried cytb gene variants associated with atovaquone resistance. Phylogenetic analysis revealed clustering of most isolates with those from Japan and China, except for one isolate forming a distinct subclade. Haplotype network analysis indicated a high diversity with 22 distinct haplotypes among the B. gibsoni isolates, emphasizing the genetic variability within the studied population. CONCLUSION: In conclusion, the cytb gene exhibited remarkable conservation among the twenty-four B. gibsoni isolates studied and the study represents the first genetic diversity assessment of B. gibsoni using the cytb gene in dogs from India. These findings shed light on the genetic characteristics of B. gibsoni in the region and provide valuable insight for addressing the challenges posed by this life-threatening disease in dogs.

First report of Ikeda genotype of Theileria orientalis in Mithun (Bos frontalis) from northeastern hilly region of India.

Oriental theileriosis caused by Theileria orientalis, previously considered a benign disease, is posing a significant threat to the livestock industry across the globe. To elucidate the prevalence of Theileria orientalis in ticks and their host, the Mithun, a comprehensive study was undertaken in the two northeastern states of India, viz. Nagaland and Arunachal Pradesh. A total of 340 of Rhipicephalus microplus ticks and 25 Ambylomma sp. ticks were screened for the presence of Theileria orientalis through PCR. Among the R. microplus ticks examined, 25 of them tested positive for T. orientalis infection whereas none of the Amblyomma ticks was positive. Additionally, a total of 275 blood samples were collected from Mithun from Arunachal and Nagaland and 31 animals were found to be positive for T. orientalis infection. Notably, six positive cases were identified in Porba (Phek district), six in Tening, and one in Bamsiakilwa village (Peren district) of Nagaland. Moreover, out of the 41 animals examined at Medziphema farms, Nagaland, 18 were found to be positive for T. orientalis infection. Moreover, the phylogenetic investigation has unveiled the presence of the highly pathogenic Type 2 (Ikeda) T. orientalis genotype in Mithun, supported by a strong bootstrap value of 100%. This study marks the initial documentation of oriental theileriosis in mithun. It underscores the need for vigilant monitoring and active surveillance of mithun populations in the northeastern states of India. Timely treatment of infected animals is imperative to avert economic losses for the farmers.

Scientometric Analysis of Gastrointestinal Parasites Prevalence in Sheep and Goats of India.

PURPOSE: In the present study, gastrointestinal parasites (GIP) prevalence in sheep and goats from India was estimated by scientometrics. METHODS: The GIP prevalence studies (86) reported during 1998-2021 was obtained from online databases, and offline literatures, meta-analysis was undertaken by using "meta" package in R-Software. RESULTS: The pooled GIP prevalence in India was 65% (95% level CI 56-74%, PI 12-96%) in sheep, 74% (95% level CI 66-80%, PI 14-98%) in goats and 68% (95% level CI 62-73%, PI 15-96%) in sheep and goats. Period-wise analysis revealed a higher GIP prevalence during 1998-2010 than the recent periods. Among the zones, GIP prevalence was higher in the Central zone (79%) in sheep, North zone (82%) in goats, and Central zone (78%) in sheep and goats. Based on the state-wise analysis, a higher GIP prevalence was observed in Haryana for sheep, Himachal Pradesh for goats, and Uttarakhand for sheep and goats. In India, a higher prevalence was reported by nematodes than other parasite classes. Based on climatic regions, a higher GIP prevalence was observed in semi-arid Steppe type region (84%). CONCLUSION: The high prevalence zones, states, species, sample types, parasite classes, parasite species and climate regions of GIP will be useful in decision-making and resource use efficiency by policymakers and stake holders. There is an urgent need to prevent the occurrence of GIP infections in sheep and goats by adopting scientific management practices, effective therapeutic measures, and hygienic practices on farms to augment the economic benefits to sheep and goat farmers in India.

Epidemiological analysis of cattle ticks and tick-borne pathogens in Gadag district, Karnataka state in India.

In the present study, epidemiological analysis on 839 ticks collected from 50 cattle in Gadag district, Karnataka state, tick identification and detection of tick-borne pathogens was conducted by PCR, sequencing, and phylogeny. The morphological identification revealed that Haemaphysalis spp. [48.6%], Rhipicephalus spp. [48.4%], and Hyalomma spp. [3.0%] tick genera in Gadag district. Further, a higher infestation of Haemaphysalis spp. [69.0%] and Rhipicephalus spp. [62.3%] in Shirahatti and Gadag taluk, respectively was observed. Based on the taluk-wise and tick genus-wise analysis, a higher number of ticks was present in the dewlap region of cattle body sites, except for Hyalomma spp., the majority of which was present in the neck. Tick genus prevalence was 45.1, 42.7%, and 12.2 for Haemaphysalis spp., Rhipicephalus spp., and Hyalomma spp., respectively. The mean tick per cattle was 11.6, 11.0, and 2.5 for Rhipicephalus spp., Haemaphysalis spp., and Hyalomma spp., respectively. The prevalence of Anaplasma marginale, Babesia spp., and Rickettsia rickettsii was 8.0, 6.4, and 6.4%, respectively in the tick DNA samples and was negative for Ehrlichia and Theileria spp. The sequencing of the cytochrome oxidase subunit 1 gene revealed the presence of Haemaphysalis bispinosa, Rhipicephalus decoloratus, and Rhipicephalus microplus tick species in the Gadag district. The phylogenetic analysis revealed the tick species have similarities and identity with the isolates from India and neighboring countries. Thus, the study provides knowledge on tick genus distribution and tick-borne pathogens in Gadag district, Karnataka which will help in developing the control and prevention strategies by the policymakers and for profitable dairy farming by farmers.

Development of an enzyme linked immunosorbent assay using recombinant cathepsin B5 antigen for sero-surveillance of bovine tropical fasciolosis.

Bovine tropical fasciolosis, caused by Fasciola gigantica, is a major parasitic disease in tropical countries responsible for significant production losses in animal husbandry practices. The disease is transmitted by the Radix sp. snails. In the early developmental stage of the parasite, the juveniles and immature flukes cause considerable damage to the liver parenchyma of the bovine host while migrating through the liver. The cathepsin (cat) B5 is a cysteine protease that is present in the excretory-secretory product of the fluke both in immature and adult stages. The early detection of fasciolosis is very critical in effective disease management. In this study, the cathepsin B5 gene from newly excysted juveniles were cloned, sequenced and analyzed. The phylogenetic analysis revealed existence of two distinct clades. The clade I includes cat B 1 to B3 whereas clade II consist of cat B4 to B7. Further, the present study was aimed to develop an enzyme linked immuno sorbent assay (ELISA) using recombinant cat B5 antigen. The developed enzyme immuno assay showed 95.3 % sensitivity and 92.4 % specificity with a cut-off of 60 % percent positive. It revealed weighted Kappa value as 0.768 (95 % CI 0.648-0.889) when compared with ELISA using native cathepsin protein. Hence, the developed assay can be exploited as a potent tool in the diagnosis and sero-surveillance of bovine tropical fasciolosis.

An extensive analysis of Codon usage pattern, Evolutionary rate, and Phylogeographic reconstruction in Foot and mouth disease (FMD) serotypes (A, Asia 1, and O) of six major climatic zones of India: A comparative study.

Foot and mouth disease (FMD) is a major economically important viral disease of cloven-hoofed livestock globally. The FMD virus (FMDV) spreads widely in confined, cool, and humid climatic conditions. Being an RNA virus, FMDV is genetically unstable, and its genome evolution is highly influenced by mutational pressure. The climatic and environmental conditions have a significant impact on mutational pressure. The present study is a primary effort to establish a comprehensive relationship between climatic factors and the molecular evolutionary pattern of serotypes FMDV circulating in India. In this study, isolates of three serotypes (A, Asia 1, and O) were selected from six major climatic zones of India (Montane, Humid subtropical, Tropical wet and dry, Tropical wet, Semi-arid and Arid). Based on the full genome nucleotide sequence data, the codon usage bias, evolutionary and phylogeographic analysis was carried out. The study revealed that the codon use bias indicators in the FMDV serotypes differed significantly depending on the climatic zones. It implies that the selection and mutational pressure influence the codon usage pattern indices, with mutational pressure taking precedence in determining the codon usage bias of the FMDV genome. The tMRCA was estimated to be 1977, 1956, and 1953 for Indian FMD virus serotype-A, Asia 1, and O respectively which is around 32, 60, and 61 years before its actual identification in the field. Based on the evolutionary rates the serotype O is evolving rapidly compare to other serotypes in India. Virus transmission across the region was evident from the phylogeographic analysis. The integrated analysis of codon usage bias, evolutionary rate, and phylogeography analysis signifies the major role of mutational and selection pressure, implying that the FMD virus co-evolution and adaptations are highly influenced by climatic/environmental factors.

Bovine babesiosis in India: Estimation of prevalence by systematic review and meta analysis.

Bovine babesiosis is a serious threat to the livestock sector especially in tropical countries like India. Understanding the epidemiology of the disease in the country is essentially important in strategizing the available methods to effectively control the disease. Keeping this as the background, the present study was undertaken to estimate the pooled prevalence of bovine babesiosis in India. The relevant literature pertaining to bovine babesiosis was identified and a total of 49 studies published between 1983 and 2018 were included in the final systematic review and meta-analysis. Meta-analysis was conducted using meta-package of R software and prevalence estimates were calculated. Bovine babesiosis was reported from 21 states of India with pooled prevalence estimate of 6% (95% CI = 4%-9%) using random effect model. Zone wise analysis revealed highest pooled prevalence in the west zone and north zone (8%) followed by east zone (7%), central zone (6%), south zone (4%) and northeast zone (4%). The results of meta-analysis indicated high variability between studies. In addition, the pooled seroprevalence was high (29%) compared to prevalence of active infection (5%) of bovine babesiosis in India. Further, the pooled prevalence estimate of B. bigemina infection in India was more (7%) compared to B. bovis infection (1%). The estimation of prevalence of active infection and seroprevalence separately will helps to understand the actual disease prevalence in the country. The study indicated the wide prevalence of bovine babesiosis in India which urges for immediate mitigation strategies.

Exploration of machine learning models to predict the environmental and remote sensing risk factors of haemonchosis in sheep flocks of Rajasthan, India.

Globally haemonchosis in sheep is a known devastating disease imposing considerable economic loss. Understanding the environmental risk factors and their role is essentially required to manage the disease successfully. In this study, 14 years' disease data was analysed to predict the risk factors responsible for the occurrence of the disease. Season-wise analysis revealed high incidence during monsoon and post-monsoon and least in winter and summer seasons. The linear discriminant analysis (LDA) revealed the significant environmental and remote sensing risk factors contributing to haemonchosis incidence as enhanced vegetation index, leaf area index, potential evapotranspiration and specific humidity. Further, significant ecological and environmental risk factors identified using LDA were subjected to the climate-disease modelling and risk maps were generated. Basic reproduction number (R0) was estimated and was ranged from 0.76 to 2.08 for >1000 egg per gram of faeces (EPG) in four districts whereas R0 values of 1.09-1.69 for >2000 EPG in three districts indicating the severity of the infection. The random forest and adaptive boosting models emerged out as best fitted models for both the EPG groups. The results of the study will help to focus on high-risk areas of haemonchosis in sheep to implement the available control strategies and better animal production globally.

Silent Trypanosoma evansi infection in humans from India revealed by serological and molecular surveys, and characterized by variable surface glycoprotein gene sequences.

BACKGROUND: The importance of emerging atypical human trypanosomosis is gaining momentum due to increasing detection and its possible impact on human health. A cross sectional study of atypical human trypanosomosis due to Trypanosoma evansi was carried out in Kolkata and Canning area of West Bengal state of India where previously a death was reported. METHODS: In this study blood and serum samples from 173 individuals were collected during August to December 2014. To check the presence of antibodies against T. evansi, card agglutination test and for the presence of T. evansi specific DNA, PCR were conducted. RESULTS: T. evansi infection was identified in 5.2% (9/173) human blood samples by CATT serological test (Card agglutination test for trypanosomosis). PCR targeting VSG gene sequences suggested active T. evansi infection in 2.89% (5/173). VSG gene sequences herein determined for five isolates from human cases shared high similarity (89.4-100%). Phylogenetic inference clustered the human isolates with other isolates from different host species from India and other countries, forming a clade exclusive of Indian isolates (84.0 to 100% sequence similarity). CONCLUSION: First report of symptomless human T. evansi infection detected by combined serological and PCR assays. First phylogenetic analysis of VSG gene sequences including human isolates of T. evansi in which Indian isolates of T. evansi from human and other hosts clustered in a single clade.

Seroprevalence of Infectious bovine rhinotracheitis (IBR) in India: A 5-year study.

Infectious bovine rhinotracheitis (IBR) is a highly contagious disease of bovines causing respiratory symptoms, abortions, and reduced milk yield, leading to huge economic losses. Reports on seroprevalence in bovines in India are available and restricted to districts/states. In the present study, a nationwide seroprevalence of IBR in bovines was conducted to provide a national IBR seroprevalence to the Chief Veterinarian who in turn can design the control strategies. A total of 15,592 cattle and buffalo serum samples from 25 states and 3 Union Territories viz., Jammu and Kashmir, Puducherry, and Andaman and Nicobar Islands were tested for IBR antibodies using Avidin­Biotin (AB) ELISA. Cumulative seropositivity was found to be 31.37%. Maharashtra and Rajasthan states, part of the west zone of the country, showed the highest and lowest seroprevalence, respectively. A total of 11,423 cattle and 4,169 buffalo serum samples were tested, which showed 33.91% and 24.39% seropositivity, respectively. India has the highest buffalo population. Presently, India no IBR vaccination programs are implemented in India. Considering the high seroprevalence, the authorities should plan control strategies for vaccinating dairy cows and buffaloes in India.

Existence of genetic lineages within Asian genotype of Taenia solium-Genetic characterization based on mitochondrial and ribosomal DNA markers.

Taenia solium cysticercosis is a potentially eradicable neglected zoonotic disease with public health importance. The genetic lineages of T. solium in Asia and Africa/America are distinct and the genetic composition of the parasite was found to influence the clinical symptoms in patients with cysticercosis. In the present study, the Cysticerci collected from pigs of two southern states of India (Karnataka and Andhra Pradesh) were genetically characterized based on mitochondrial (COX 1 and Cyt b) and ribosomal (ITS-1 and TBR) DNA markers. The study confirms the existence of two mitochondrial lineages of the parasite as Asian and African/American. Cytochrome oxidase 1 (COX 1) based analysis revealed the existence of two sub-lineages of the parasite within the Asian lineage based on the polymorphism at 994 position as 994A/G. In India, both the sub-lineages were identified and genetic divergence among different Indian isolates was evident. Further, the sequence analysis of Cytochrome B (Cyt b) revealed the existence of six sub-lineages of T. solium in India as 69T/69G, 97A/97G as well as 264T/264C. The analysis of nucleotide sequence of large subunit ribosomal DNA (TBR) revealed the existence of two sub-lineages in India based on the deletion of a nucleotide at 624th position. The cysts collected in the present study were more closely related to those of China and Indonesia than with other Indian isolates. Further, the sequence analysis did not indicate the presence of Taenia asiatica in the examined pigs and African/American lineages of T. solium. The results of the present study help to better understand the genetic diversity of T. solium in India.

Molecular survey and phylogenetic analysis of tick-borne pathogens in ticks infesting cattle from two South Indian states.

In this study, the molecular survey of cattle ticks and tick-borne pathogens in various agroclimatic zones in Karnataka and Kerala states, India, and phylogenetic analysis of gene sequences were accomplished. Overall, 240 pooled tick DNA samples from two states were used for the identification of three tick genera and nine tick-borne pathogens by using the PCR method and sequencing. The distribution of Haemaphysalis (Ha.), Hyalomma (Hy.), and Rhipicephalus (R.) species were 5.0, 17.5, and 65.8% in Karnataka and 5.8, 11.7, and 65.0% in Kerala, respectively. The prevalence of Anaplasma marginale, Babesia bovis, Rickettsia species, and Trypanosoma evansi was 8.3, 0.8, 6.7, and 0.0% in Karnataka and 14.2, 0.0, 8.3, and 8.3% in Kerala, respectively. The pooled tick DNA samples were negative for Bartonella species, Borrelia species, Coxiella burnetti, Pasteurella multocida, and Theileria species. The season-wise analysis revealed a high occurrence of Ha. species in all seasons except for post-monsoon, Hy. and Rhipicephalus species in monsoon season in Karnataka, and all three tick genera were present in monsoon season in Kerala. The sequence analysis of mitochondrial cytochrome oxidase subunit 1 gene facilitated the identification of tick species namely, Ha. bispinosa, Ha. japonica, Hy. excavatum, R. annulatus, R. decoloratus, R. microplus, and R. sanguineus. The Rhipicephalus species was a major tick in these two states, and Rickettsia endosymbiont and Trypanosoma evansi in tick were detected in this study. This study represents the first report about the presence of Rickettsia massiliae in Ha. bispinosa in Karnataka and Trypanosoma evansi in R. species in Kerala. Phylogenetic analysis revealed sequence homology between the different isolates from India and neighbouring countries. Thus, the study provides key information on the distribution of ticks and tick-borne pathogens of cattle in Karnataka and Kerala, which will aid in developing and strategizing effective control measures.

Migratory Gaddi sheep and goats as potential carriers of Theileria infection: a molecular survey.

Theileriosis caused by parasites of the genus Theileria, is a vector-borne haemoprotozoan parasitic disease of critical concern in small ruminants. This study aimed to explore the infection status of migratory Gaddi sheep and goats with parasites from the Theileria genus in concurrence with ectoparasite infestations using molecular methods. Seventy three apparently healthy animals were randomly sampled from different flocks of migratory Gaddi sheep and goats and were systematically screened for ectoparasitic infestations. Molecular investigation for theileriosis was conducted using the genus wide polymerase chain reaction (PCR) technique. Out of 56 (76.71%) animals positive for the genus Theileria, 2 randomly selected amplicons were sequenced and subjected to BLAST analysis and were showing 99.71% identity with Theileria luwenshuni, a pathogenic Theileria species of small ruminants. To confirm the presence of T. luwenshuni, species-specific PCR was attempted to identify that 38 (52.05%) animals were infected by T. luwenshuni. On analysing the molecular prevalence data of Theileria to the ectoparasitism, it was evident that the infection existed in the animals irrespective of the type of ectoparasitic infestation and even T. luwenshuni was found in non-infested animals also. This is the first report of subclinical infections of T. luwenshuni in sheep and goats of Northern India and its potential carrier status. The asymptomatic carrier status of these nomadic animals is a matter possessing serious implications on the disease transmission rates and the production economics of small ruminant production in this region.

Animal disease surveillance: Its importance & present status in India.

Animal disease surveillance encompasses systematic collection of long-term data on disease events, risk factors and other relevant parameters followed by analyzing the same with reference to temporal and spatial characteristics to arrive at a conclusion so that necessary preventive measures can be taken. In India, the animal disease surveillance is done through National Animal Disease Reporting System, which is a web-based information technology system for disease reporting from States and Union Territories with the aim to record, monitor livestock disease situation and to initiate the preventive and curative action in a swift manner during disease emergencies. National Animal Disease Referral Expert System is a dynamic geographic information system and remote sensing-enabled expert system that captures an incidence of 13 economically important livestock diseases from all over the country and also provides livestock disease forecasting. The laboratories under State and Central governments, several research institutes under the Indian Council of Agricultural Research and veterinary colleges are involved in livestock disease diagnosis including zoonotic diseases. An integrated surveillance system is necessary for early detection of emerging/zoonotic diseases in humans. This review provides information on disease reporting and surveillance systems in animal health sector and the need for One Health approach to improve and strengthen the zoonotic disease surveillance system in India.

Fasciolosis in India: An overview.

Fasciolosis in ruminants is a relentless constraint in the livestock industry across the world. Immuno-prophylactic vaccines against fasciolosis may not come up in near future, rendering the control of this scourge with chemotherapy and snail population control. With the alarming threats of anti-fasciolid drug resistance reported from certain parts of the world; the control of fasciolosis should be directed towards the development of rapid and reliable diagnostic tools to execute the specific and discrete treatment. Understanding the epidemiology of Fasciola, its genomics and proteomics, host-parasite interplay, and advances in drug design research is vital for improving animal health that would ultimately succour to meet the ever-increasing demand for food. Due to possible differences in immune response depending on the species of the host and parasite, immuno-prophylactic studies in India should aim at achieving protective efficacy in buffalo against F. gigantica as workers from other countries concentrate primarily on vaccination of cattle and sheep against F. hepatica. This manuscript focused on the research that has been carried out in India for understanding the epidemiology, genetic diversity, immuno-diagnosis, and possible control measure in terms of immuno-prophylaxis and drug designing against tropical fasciolosis caused by Fasciola gigantica.

Bovine babesiosis: An insight into the global perspective on the disease distribution by systematic review and meta-analysis.

Bovine babesiosis is continuing as a great threat to the livestock sector causing havoc production losses with significant morbidity and mortality. Being a tick-borne disease, the great complexity in the agent-host- vector relationship has severely hampered the sincere efforts towards the development of an effective vaccine against bovine babesiosis. In these circumstances, assessing the global scenario of disease prevalence is a prerequisite to strategize the available control measures. Keeping this in view, the objective of this study was to estimate the pooled prevalence of bovine babesiosis globally. The literature search was conducted to identify all relevant published articles reporting the prevalence of bovine babesiosis and a total of 163 studies were found eligible for final systematic review and meta-analysis. Meta-analysis was conducted using meta package of R software and summary estimates of the prevalence were calculated. Meta analysis of 81099 samples from 62 countires representing six continents revealed pooled global prevalence of bovine babesiosis as 29% (95% CI = 24%-34%) with estimated prevalence of active infection as 16% (95% CI = 13%-20%) and seroprevalence as 50% (95% CI = 45%-56%) using random effects model. Continent wise highest prevalence of bovine babesiosis in South America 64% (95% CI = 49%-77%) and lowest in Asia 19% (95% CI = 14%-25%). Highest prevalence was estimated with B. bigemina 22% (95% CI = 18%-27%) and least prevalence was recorded with B. divergens 12% (95% CI = 2%-46%). The pooled prevalence estimates generated in the study is revealing an increase in disease trend and the need for immediate planning of mitigation strategies paralleled with the development of early diagnostic methods to reduce the impact of disease throughout the world.

Isolation and characterization of Cu/Zn-superoxide dismutase in Fasciola gigantica.

A full-length complementary DNA (cDNA) encoding Cu/Zn-superoxide dismutase was isolated from Fasciola gigantica that on nucleotide sequencing showed a close homology (98.9%) with Cu/Zn-superoxide dismutase (SOD) of the temperate liver fluke, F. hepatica. Expression of the gene was found in all the three developmental stages of the parasite viz. adult, newly excysted juvenile and metacercaria at transcriptional level by reverse transcription-polymerase chain reaction (RT-PCR) and at the protein level by Western blotting. F. gigantica Cu/Zn-SOD cDNA was cloned and expressed in Escherichia coli. Enzyme activity of the recombinant protein was determined by nitroblue tetrazolium (NBT)-polyacrylamide gel electrophoresis (PAGE) and this activity was inactivated by hydrogen peroxide but not by sodium azide, indicating that the recombinant protein is Cu/Zn-SOD. The enzyme activity was relatively stable at a broad pH range of pH 4.0-10.0. Native Cu/Zn-superoxide dismutase protein was detected in the somatic extract and excretory-secretory products of the adult F. gigantica by Western blotting. NBT-PAGE showed a single Cu/Zn-SOD present in the somatic extract while three SODs are released ex vivo by the adult parasite. The recombinant superoxide dismutase did not react with the serum from buffaloes infected with F. gigantica. The role of this enzyme in defense by the parasite against the host reactive oxygen species is discussed.

Genetic characterization of Fasciola gigantica from different geographical regions of India by ribosomal DNA markers.

Ribosomal DNA sequences of the second internal transcribed spacer (ITS-2) and 28S ribosomal DNA (618 bp) of Fasciola gigantica collected from cattle and buffaloes from four different geographical locations of India, were characterized for genotyping. ITS-2 sequence was analyzed in 28 worms that was typical of F. gigantica and differed at six positions, with one of these being a distinguishing deletion (T) at the 327th position in F. gigantica relative to F. hepatica. However, Fasciola specimens also showed intraspecies sequence polymorphism in the ITS-2, with two different ITS-2 sequences existing in the ribosomal DNA (rDNA) array within a single Fasciola worm. One of the sequences was identical to that of F. gigantica and the other showed extensive sequence polymorphism in the ITS-2. Using BspH1-restriction fragment length polymorphism, six variable ITS-2 sequences in F. gigantica were identified within these parasite specimens and were found distributed in these four geographical regions. 28S rDNA sequence of 24 flukes, collected from the above four geographical regions, showed a single nucleotide polymorphism at 284th nucleotide (G/A). Analyzing the sequence data of 28S rDNA of F. gigantica available from some African and Asian countries for this polymorphic 284th nucleotide position, it is proposed that there are two basic lineages of the F. gigantica for 28S rDNA existing in the fluke populations from five African and several Asian countries.