Haemoparasites-Challenging and Wasting Infections in Small Ruminants: A Review

Current status of ruminant anaplasmosis in Algeria: a systematic review and meta-analysis

Anaplasmosis is an emerging infectious disease that is being recognised all over the world, with impact on animal health.This systematic review and meta-analysis aimed to assess the rate infection of Anaplasma spp. infection in Algerian ruminants. Three databases were searched to identify eligible studies for the final systematic review and meta-analysis. The 'meta' package in the R software was used for the meta-analysis, and the random effects model was chosen to pool the data. Meta-analysis encompasses 14 research papers spanning 19 years (2004-2023), out of an initial pool of 737 articles retrieved from various databases. The study included a total of 1515 cattle, 190 sheep, and 310 goats, and the overall Anaplasma infection rate was estimated at 28% (95% CI, 17-41%). The analysis revealed varying infection rates among species, with cattle at 20%, sheep at 30%, and goats at 61%. Five classified species and two unclassified strains belonging to Anaplasma genus were identified in ruminants, which are A. marginale, A. centrale, A. bovis, A. ovis, A. phagocytophilum, A. phagocytophilum-like strains, and A. platys-like strains. Among these, A. marginale was prevalent in ten out of eleven cattle studies. The data also revealed regional variations, with Northeastern Algeria showing a higher infection rate (26%) compared to North-central Algeria (9%). In the subgroup analysis, clinically healthy cattle had a higher infection rate (28%) compared to suspected disease cattle (16%). Molecular biology screening methods yielded a significantly higher infection rate (33%) than microscopy (12%). Gender analysis suggested slightly higher infection rates among male cattle (19%) compared to females (16%). Age analysis indicated that Anaplasma infection was more common in cattle less than 12 months (14%) compared to those over 12 months (9%). This systematic review provides valuable insights, highlighting the need for continued surveillance and potential preventive strategies in different regions and among different animal populations in Algeria.

Anaemia in South American camelids - an overview of clinical and laboratory diagnostics

South American camelids (SACs) play an increasing role in veterinary care in Europe. Many alpacas or llamas presented to veterinarians suffer from anaemia, regularly with a packed cell volume (PCV) below 0.10 l/l, which is a life-threatening condition for the animals. This review article presents clinical and laboratory diagnostic tools for the diagnosis of anaemia in SACs. Clinical identification of anaemic animals can be performed by assessing the FAMACHA© score and the Body Condition Score (BCS), since anaemia in alpacas and llamas correlates with pale mucous membranes and a lowered BCS. Haematological examination of a blood sample can provide a more differentiated diagnosis of anaemia in SACs. A common finding is regenerative anaemia with an increased number of reticulocytes that is often caused by blood loss due to Haemonchus contortus. Changes in a blood smear from an alpaca or llama with regenerative anaemia may include normoblasts (nucleated red blood cells), anisocytosis, poikilocytosis, polychromasia, Howell-Jolly bodies or basophilic stippling. Furthermore, non-regenerative anaemia, often caused by trace element deficiency or cachexia, can also occur.

Systematic Review and Meta-Analysis on Piroplasma spp. Infection and Co-infection with Anaplasma marginale in Domestic Ruminants from Algeria

BACKGROUND

Piroplasmosis and anaplasmosis stand out as the primary diseases affecting livestock during periods of tick activity. These vector-borne diseases continue to emerge worldwide, exerting a detrimental impact on both animal health and national economies. The purpose of this study is to assess the prevalence of Piroplasma spp. and its co-occurrence with Anaplasma marginale in domestic ruminants in Algeria.

METHODS

Three databases were systematically reviewed to identify eligible studies for the final meta-analysis, following the PRISMA statement. The 'meta' package in the R software was employed for the meta-analysis with the random effects model chosen for data pooling.

RESULTS

The meta-analysis encompasses 14 research papers spanning a 19-year period (2004-2023). Theileria spp. was identified in all studies, covering 1675 cattle, 190 sheep, and 128 goats, yielding an overall Theileria infection rate of 45% (95% CI 26-65%). Specifically, cattle had a 59% infection rate, while sheep and goats had rates of 18% and 20%, respectively. Babesia spp. was found in nine studies, involving 1183 cattle and 190 sheep, resulting in an overall Babesia infection rate of 7% (95% CI 4-15%), with cattle and sheep having rates of 10% and 3%, respectively. Notably, eight Piroplasma species T. annulata, T. orientalis, T. buffeli, T. equi, Theileria sp., B. bovis, B. bigemina, and B. occultans were detected in cattle, with T. annulata being the most prevalent at 54%. Regional disparities and host factors also impacted infection rates, with higher rates in Northeastern Algeria and among suspected disease cattle. Additionally, gender, age, and breed influenced cattle susceptibility to Theileria infection. Furthermore, six distinct co-infections between Piroplasma spp. and A. marginale were observed, with T. annulata/A. marginale identified in six studies, demonstrating an 8.3% co-infection rate.

CONCLUSION

This analysis offers crucial insights into the current status of Piroplasmosis and its co-infection with A. marginale in Algerian domestic ruminants, providing valuable data for surveillance and prevention strategies.

Experimental infection of non-immunosuppressed and immunosuppressed goats reveals differential pathogenesis of Babesia aktasi n. sp

Babesiosis is an acute and persistent tick-borne disease caused by protozoan parasites of the genus Babesia. These hemoparasites affect vertebrates globally, resulting in symptoms such as high fever, anemia, jaundice, and even death. Advancements in molecular parasitology revealed new Babesia species/genotypes affecting sheep and goats, including Babesia aktasi n. sp., which is highly prevalent in goats from Turkiye's Mediterranean region. The objective of this study was to investigate the pathogenesis of B. aktasi infection in immunosuppressed (n=7) and non-immunosuppressed (n=6) goats. These animals were experimentally infected with fresh B. aktasi infected blood, and their clinical signs, hematological and serum biochemical parameters were monitored throughout the infection. The presence of parasites in the blood of immunosuppressed goats was detected by microscopic examination between 4 and 6 days after infection, accompanied by fever and increasing parasitemia. Goats that succumbed acute disease exhibited severe clinical signs, such as anemia, hemoglobinuria, and loss of appetite. However, the goats that survived showed milder clinical signs. In the non-immunosuppressed group, piroplasm forms of B. aktasi were observed in the blood within 2-5 days after inoculation, but with low (0.01-0.2%) parasitemia. Although these goats showed loss of appetite, typical signs of babesiosis were absent except for increased body temperature. Hematological analysis revealed significant decreases in the levels of red blood cells, leukocytes and platelet values post-infection in immunosuppressed goats, while no significant hematological changes were observed in non-immunosuppressed goats. In addition, serum biochemical analysis showed elevated transaminase liver enzymes levels, decreased glucose, and lower total protein values in the immunosuppressed group post-infection. Babesia aktasi, caused mild disease with minor clinical symptoms in non-immunosuppressed goats. However, in immunosuppressed goats, it exhibited remarkable pathogenicity, leading to severe clinical infections and death. In conclusion, this study provides valuable insights into the pathogenicity of the parasite and will serve as a foundation for future research aimed at developing effective prevention and control strategies against babesiosis in small ruminants. Further research is required to investigate the pathogenicity of B. aktasi in various goat breeds, other potential hosts, the vector ticks involved, and its presence in natural reservoirs.

In silico analysis of sporozoite surface antigen 1 of Theileria annulata (TaSPAG1) for multi-epitope vaccine design against theileriosis

Tropical theileriosis is a protozoan infection caused by Theileria annulata, which significantly affects cattle worldwide. This study was aimed to analyze the TaSPAG1 protein and design a novel multi-epitope vaccine candidate. Online tools were employed for the prediction of Physico-chemical properties, antigenicity, allergenicity, solubility, transmembrane domains and signal peptide, posttranslational modification (PTM) sites, secondary and tertiary structures as well as intrinsically disordered regions, followed by identification and screening of potential linear and conformational B-cell epitopes and those peptides having affinity to bind bovine major histocompatibility complex class I (MHC-I) molecules. Next, a multi-epitope vaccine construct was designed and analyzed. This 907-residue protein was hydrophilic (GRAVY: -0.399) and acidic (pI: 5.04) in nature, with high thermotolerance (aliphatic: 71.27). Also, 5 linear and 12 conformational B-cell epitopes along with 8 CTL epitopes were predicted for TaSPAG1. The 355-residue vaccine candidate had a MW of about 35 kDa and it was antigenic, non-allergenic, soluble and stable, which was successfully interacted with cattle MHC-I molecule and finally cloned into the pET28a(+) vector. Further wet studies are required to assess the vaccine efficacy in cattle.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-023-00153-5.

Molecular Prevalence and Genetic Diversity Based on Msp1a Gene of Anaplasma ovis in Goats from Türkiye

Anaplasma ovis is a tick-borne obligated intraerythrocytic bacterium that infects domestic sheep, goats, and wild ruminants. Recently, several studies have been carried out using 16S rRNA and msp4 genes to identify the genetic diversity of A. ovis. Instead of these genes, which are known to be highly stable among heterologous strains, Msp1a, which is accepted as a stable molecular marker to classify A. marginale strains, was used in A. ovis genetic diversity studies. The genetic diversity of A. ovis strains according to the Msp1a gene has not been extensively reported. Therefore, the purpose of this study was to examine the genetic diversity of A. ovis in goats specifically using analysis of the Msp1a gene. Blood samples were taken from the vena jugularis to the EDTA tubes from 293 randomly selected goats (apparently healthy) in the Antalya and Mersin provinces of Mediterranean region of Türkiye. The Msp1a gene of A. ovis was amplified in all DNA samples through the use of PCR, using a specific set of primers named AoMsp1aF and AoMsp1aR. Among the amplified products, well-defined bands with different band sizes were subjected to sequence analysis. The obtained sequence data were converted into amino acid sequences using an online bioinformatics program and the tandem regions were examined. The Msp1a gene of A. ovis was amplified in 46.1% (135 out of 293) of the goats. Through tandem analysis, five distinct tandems (Ao8, Ao18, Tr15-16-17) were identified, and it was found that three of these tandems (Tr15-16-17) were previously unknown and were therefore defined as new tandems. The study also involved examination of ticks from goats. It was observed that the goats in the area were infested with several tick species, including Rhipicephalus bursa (888/1091, 81.4%), R. turanicus (96/1091, 8.8%), Dermacentor raskemensis (92/1091, 8.4%), Hyalomma marginatum (9/1091, 0.8%), and R. sanguineus s.l. (6/1091, 0.5%). This study provides important data for understanding the genetic diversity and evolution of A. ovis based on tandem repeats in the Msp1a protein.

Clinical, hematological and molecular evaluation of piroplasma and Anaplasma infections in small ruminants and tick vectors from Kurdistan province, western Iran

Tick-borne haemoparasite infections are a major challenge in small ruminant (SR) production across tropical areas. The present study evaluated the prevalence of Theileria, Babesia and Anaplasma in SRs and their tick vectors and estimated the association between pathogen prevalence with clinical hematological findings among SR populations in Kurdistan province, western Iran. In total, 250 blood samples and 250 tick species (one per animal) were collected from SR populations, along with clinical and hematological examinations. Microscopy of blood smears and molecular analysis were performed to detect potential infection with Theileria, Babesia and Anaplasma. Moreover, haemoparasites were explored in the isolated ticks using semi-nested PCR. Based on microscopy, the prevalence of Theileria, Anaplasma and Babesia infections was 91.2%, 23.2% and 2.4%, respectively. Semi-nested PCR analysis of blood samples demonstrated 86.8%, 78.8% and 14% prevalence for T. ovis, A. ovis and B. ovis, respectively. Dermacentor marginatus and Rhipicephalus turanicus were predominant isolated tick vectors from SR, while D. marginatus was the most contaminated tick in all investigated counties. There were, also, a statistically significant association between the estimated molecular prevalence rates with semi-yellow conjunctiva (A. ovis), body temperature (T. ovis and A. ovis), heart rate (T. ovis and B. ovis), mean white blood cell count (T. ovis and A. ovis), mean red blood cell count (T. ovis and B. ovis), as well as mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration in all haemoparasite infections. Future studies are recommended to reveal the epidemiology of such infections in SRs in Iran.

Small Ruminant Piroplasmosis: High Prevalence of Babesia aktasi n. sp. in Goats in Türkiye

Small ruminant piroplasmosis is the hemoparasitic infection of sheep and goats caused by Babesia and Theileria species responsible for clinical infections with high mortality outcomes. The disease is transmitted by ixodid ticks and prevalent in the tropical and subtropical regions of the world, including Türkiye. A prevalence survey, using molecular methods, is conducted in this study to determine the frequency of newly defined Babesia aktasi n. sp. and other tick-borne piroplasm species in small ruminants in Turkiye. A total of 640 blood samples from sheep (n = 137) and goats (n = 503) were analyzed by nested PCR-based reverse line blot (RLB) hybridization. The results show that 32.3% (207/640) of apparently healthy, small ruminants are infected with three Theileria and two Babesia species. Babesia aktasi n. sp. was the most prevalent species in goats, with 22.5% of samples being positive, followed by B. ovis (4%), T. ovis (2.8%), T. annulata (2.6%), and Theileria sp. (0.6%). None of the sheep samples were positive for Babesia aktasi n. sp.; however, 51.8% were infected with T. ovis. In conclusion, the findings reveal that B. aktasi n. sp. is highly prevalent in goats, but absent in sheep. In future studies, experimental infections will determine whether B. aktasi n. sp. is infectious to sheep, as well as its pathogenicity in small ruminants.

Validation of stable reference genes in peripheral blood mononuclear cells for expression studies involving vector-borne haemoparasitic diseases in bovines

Normalization of gene expression data using appropriate reference genes is critical to diminish any technical bias in an experiment involving quantitative real-time PCR (qPCR). To the best of our knowledge, this is the first report offering a systematic assessment of 14 potential reference genes (RPLP0, ACTB, RPS28, YWHAZ, SDHA, PPIA, RPS9, RPS15, UXT, GAPDH, B2M, BACH1, HMBS, and PPIB) for the identification of the most stable normalizers for qPCR of target genes in peripheral blood mononuclear cells (PBMCs) of bovines for vector-borne haemoparasitic diseases such as anaplasmosis, babesiosis, theileriosis, and trypanosomiasis. A total of 38 blood samples were collected from healthy as well as diseased cattle and buffaloes representing different haemoparasitic diseases. RNA isolated from the PBMCs was subjected to qPCR for the 14 prospective internal control genes. The comprehensive ranking of the genes was accomplished by the RefFinder tool that integrates the results of three algorithms (geNorm, NormFinder, and BestKeeper) and the comparative C_T method. RPS15, B2M, and GAPDH were ranked to be the most stable genes, whereas, PPIA and HMBS emerged to be the least suitable genes. Validation of the selected reference genes by the qPCR analysis of two immunity genes, ISG15 and GPX7 was congruent with the observations of this study. We recommend that a panel of three reference genes including RPS15, B2M, and GAPDH could prove useful in delineating the transcriptional landscape of PBMCs for vector-borne haemoparasitic diseases in bovines.

Natural Co-Exposure to Borrelia burgdorferi s.l. and Anaplasma phagocytophilum: Unraveling the Hematological Profile in Sheep

The occurrence of co-infected hosts and questing ticks with more than one tick-borne pathogen-as in the case of Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato-is expected in endemic regions. Their synergy-in terms of pathogenesis and disease severity-has been suggested previously in humans. Limited data exist on the clinicopathological alterations in co-infected sheep. In this study, we investigated the impact of A. phagocytophilum and B. burgdorferi s.l. seropositivity, alone and in combination, on the hematological parameters of naturally infected sheep. A complete blood count was performed, and indirect immunofluorescence assays were used to detect IgG antibodies against A. phagocytophilum and IgG and IgM antibodies against B. burgdorferi s.l. Single natural exposure to B. burgdorferi s.l. was characterized by low Packed Cell Volume (PCV) values and platelet (PLT) counts, while single exposure to A. phagocytophilum was characterized by low PCV values, low white blood cell (WBC) counts, and an increased risk for leukopenia and neutropenia. Co-exposure resulted in the most severe blood abnormalities; all the blood parameters decreased, and the sheep presented an increased risk for anemia. Our study showed that natural co-exposure to A. phagocytophilum and B. burgdorferi s.l. in sheep leads to more severe blood abnormalities and enhances the pathogenic processes. More studies are needed to clarify the possible background mechanisms.

Anaemia in Sheep Caused by Babesia and Theileria Haemoparasites

Piroplasmoses in sheep are caused by vector-borne apicomplexan protozoa, Babesia and Theileria. Different species are responsible for the disease; some species are more pathogenic than others and have a worldwide distribution. In this sense, these causative agents can cause anaemia in flocks. In general, these vector-borne diseases infect small ruminants and cause host-mediated pathology. In the case of Babesia species, a combination of different mechanisms is involved: red blood cell lysis due to intracellular parasite multiplication, activation of biogenic amines and the coagulation system with the possibility of disseminated intravascular coagulation. By contrast, less information is available on the different immunopathogenic mechanisms involved in the development of anaemia in sheep with theileriosis. However, the mechanisms of pathogenic action in theileriosis are similar to those studied in babesiosis. Diagnosis is based on compatible clinical signs, laboratory findings, specific diagnostic tests and the presence of the tick vector. Some of these tests detect the causative agent itself, such as direct identification by light microscopy and molecular analysis. In contrast, other tests detect the sheep's immune response to the organism by serology. Both diseases pose a significant diagnostic challenge for veterinary practitioners around the world. This review presents the most frequent clinical signs, pathogenesis and clinicopathological findings, diagnosis.

First Molecular Identification of Babesia, Theileria, and Anaplasma in Goats from the Philippines

Goats are key livestock animals and goat raising is an income-generating venture for smallholder farmers, supporting agricultural development in many parts of the world. However, goat production is often limited by various factors, such as tick-borne diseases. Goat piroplasmosis is a disease caused by apicomplexan parasites Babesia spp. and Theileria spp., while anaplasmosis is caused by bacterial Anaplasma spp. In the Philippines, the presence of Babesia, Theileria, and Anaplasma has not been reported in goats. In this study, DNA obtained from goats were molecularly screened for Babesia/Theileria and Anaplasma. Of 396, 77.02% (305/396) and 38.64% (153/396) were positive for piroplasma and Anaplasma using PCR assays targeting the 18S rRNA and 16S rRNA genes, respectively. Similarly, Babesia ovis was detected in six samples (1.52%). Representative Babesia/Theileria sequences shared 89.97–97.74% identity with each other and were most closely related to T. orientalis, T. annulata, and Theileria spp. Meanwhile, Anaplasma 16SrRNA sequences were related to A. odocoilei, A. platys, and A. phagocytophilum. This is the first molecular identification of B. ovis, Theileria spp., and Anaplasma spp. in goats from the Philippines.

Comparative Study of the Use of Doxycycline and Oxytetracycline to Treat Anaplasmosis in Fattening Lambs

Lamb icteric carcasses condemnation due to Anaplasma ovis is causing relevant economic losses. A comparative study was developed on the effects of different antibiotics to treat ovine anaplasmosis in fattening lambs. A total of 100 A. ovis naturally infected lambs were selected and randomly divided into four groups of 25 lambs: Group ID, treated with injectable doxycycline; Group OD, oral doxycycline; Group O, injectable oxytetracycline; and Group C, untreated animals for the control group. Clinical, haematological, and molecular analyses were performed before the treatment and 12 and 45 days after the beginning of the treatments, and carcass condemnation was followed after slaughter. The A. ovis bacterial load was high before the treatments in the four groups and decreased significantly 45 days after treatment in the ID and O Groups (p < 0.001). The parameters that were related to haemolysis showed similar results. At the abattoir, 15 out of the 47 examined carcasses were condemned; 7 of C Group, 6 of OD Group, 2 of O Group, and 0 of ID Group. It can be concluded that injectable doxycycline and oxytetracycline significantly reduce A. ovis bacterial load in blood and carcass condemnation at the abattoir. Further studies are needed in order to confirm these encouraging findings.

Molecular Epidemiology and Species Diversity of Tick-Borne Pathogens of Animals in Egypt: A Systematic Review and Meta-Analysis

Ticks and tick-borne pathogens (TTBPs) are listed among the most serious concerns harming Egyptian livestock’s productivity. Several reports on tick-borne pathogens (TBPs) from various geographical regions in the country were published. However, data on the molecular characterization of TBPs are the most beneficial for understanding the epidemiology of this important group of pathogens. In this study, we present the first meta-analysis on the molecular epidemiology and species diversity of TBPs infecting animals in Egypt. All published studies on TBPs were systematically collected from various databases (PubMed, Scopus, ScienceDirect, the Egyptian Knowledge Bank, and Google Scholar). Data from eligible papers were extracted and subjected to various analyses. Seventy-eight studies were found to be eligible for inclusion. Furthermore, ticks infesting animals that were molecularly screened for their associated pathogens were also included in this study to display high species diversity and underline the high infection risk to animals. Theileria annulata was used as parasite model of TBPs to study the genetic diversity and transmission dynamics across different governorates of Egypt. This study extends cross-comparisons between all published molecular data on TBPs in Egypt and provides resources from Egyptian data in order to better understand parasite epidemiology, species diversity, and disease outcome as well as the development and implementation of prevention and control methods for public health, veterinary care practitioners, and animal owners all over the country.

Molecular Reports of Ruminant Babesia in Southeast Asia

The protozoon Babesia is a blood parasite transmitted by hard ticks and commonly parasitizes ruminants such as cattle, buffaloes, goats, and sheep. Babesiosis, the disease caused by Babesia infection, has been considered a potential threat to ruminant production due to the grave and enormous impact it brings. About 125 million ruminants are at risk of babesiosis in Southeast Asia (SEA), a region composed of 11 countries. In recent decades, molecular-based diagnostic platforms, such as polymerase chain reaction (PCR) assays, have been a reliable and broadly employed tool in Babesia detection. In this article, the authors compiled and summarized the molecular studies conducted on ruminant babesiosis and mapped the species, including B. bovis, B. bigemina, B. ovata, Babesia sp. Mymensingh, Babesia sp. Hue, and B. ovis, and determined the host diversity of ruminant Babesia in SEA.

Case Report: Severe Anemia Associated With an Abomasal Fibrosarcoma in a Goat

A 10-year-old female goat was presented to the clinic with lethargy, emaciation, and pale mucous membranes. Laboratory diagnosis revealed severe anemia with regenerative character as well as melena. Blood transfusions were administered, but the animal's condition continued to deteriorate, so it was euthanized. The main finding in the necropsy was an abomasal neoplasia with two metastases in the mesenterium which was positive for vimentin, but negative for smooth muscle actin and c-kit using immunohistochemistry, indicating a fibrosarcoma that might have contributed to gastrointestinal blood loss. Further pathological findings consisted of changes in the liver cells as well as a cervical leiomyoma. These findings illustrate that intestinal blood loss due to neoplasia should also be considered in older goats with anemia.

Occurrence and Molecular Identification of Hemoparasites in Wild Mammals Kept in Rehabilitation Centers in Brazil

PURPOSE

Hepatozoonosis and piroplasmosis are diseases caused by apicomplexan protozoa that affect different types of animals, including mammals. The present study aimed to evaluate the occurrence of Hepatozoon spp. and piroplasms in wild mammals kept in captivity in rehabilitation centers in the states of Minas Gerais and Goiás, Brazil.

METHODS

For this, blood samples from 152 animals were collected and analyzed by conventional optical microscopy and polymerase chain reaction (PCR). In addition, positive PCR samples were submitted to sequencing for molecular characterization of the specimens found.

RESULTS

Microscopic analysis revealed 53 of the 152 animals (28.3%) parasitized by piroplasms. No Hepatozoon sp. was observed. On the other hand, using the primers HepF300/HepR900 and Piro1F/Piro5R, both amplifying fragments of the 18S rDNA gene, eight animals (5.2%) were positive for Hepatozoon spp. and 40 (26.3%) for piroplasms. From the sequencing of the positive samples Hepatozoon canis, Hepatozoon felis, Theileria cervi, Theileria equi and Cytauxzoon felis were identified. In addition to the aforementioned hemoparasites, some animals were found parasitized by microfilaria. Such data ratify the presence of hemoparasites in captive wild animals, and are unprecedented in the two geographical regions covered by the present study. 19.7% of mammals harbored ectoparasites of the genera Amblyomma and Rhipicephalus.

CONCLUSION

Wild mammals are infected by several pathogens that can also infect domestic animals, some of them potentially zoonotic which can directly contribute to mortality and species reduction. Therefore, a deep understanding of the parasites, the hosts and the diseases is extremely necessary so that prevention, control and treatment measures are effectively applied.

Evaluation of an Indirect Immunofluorescence Assay for the Detection of Anaplasma phagocytophilum Antigen in Ovine Buffy Coat Smears

Diagnosis of anaplasmosis is challenging considering the great variation in clinical signs and the limitations of the available diagnostic assays, while the detection of carrier animals that play a significant role in disease epidemiology as reservoirs is of great significance. In this study, we evaluated the diagnostic accuracy of a newly developed indirect immunofluorescent assay (Ag-IFAT) for the detection of A. phagocytophilum antigens in buffy coat specimens, alone and in combination with cytology, using PCR as a reference. Blood samples were collected from 138 sheep of the Chios breed from six farms in Greece. A buffy coat was extruded from the centrifuged blood. Buffy coat smears were used for cytological examination and the Ag-IFAT assay. The Ag-IFAT assay presented excellent specificity (100%) and high sensitivity (85.4%) for the detection of A. phagocytophilum antigens in buffy coats, and it has an almost perfect agreement with PCR and cytology (κ value = 0.88 and 0.85, respectively). A. phagocytophilum antigens are likely to be detected using Ag-IFAT in a PCR-positive animal, as indicated by the good performance of the assay. Overall, this assay presents high diagnostic accuracy, and it could be used for the detection of animals during the early stage of infection.

Epidemiological Study Related to the First Outbreak of Ovine Anaplasmosis in Spain

Simple Summary

Ovine anaplasmosis is an emerging disease in Europe, able to cause relevant economic losses. This disease has great significance in tropical and subtropical areas; however, climate change has facilitated the wider spread of ovine anaplasmosis throughout Europe during the last few decades. Related to the first ovine anaplasmosis outbreak that occurred in Spain in 2014, an epidemiological study was carried out in the affected area. The results show a high presence of Anaplasma ovis in the analysed flocks, indicating the high transmissibility of the bacteria.

Abstract

Ovine anaplasmosis is a vector-borne disease caused by Anaplasma ovis and mainly transmitted through tick bites. In Spain, the first outbreak of ovine anaplasmosis occurred in 2014. An epidemiological study in fifty-one farms was carried out associated with this outbreak in the affected geographical area. An epidemiological questionnaire was performed. In addition, whole blood samples were taken for molecular analysis in 47 of these farms to determine the prevalence of infection of Anaplasma ovis. A. ovis was present in 44 out of 47 PCR-analysed farms (93.6%). However, only 40.4% of the studied farms showed severe clinical signs. The clinical signs affected mainly young animals, which showed severe anaemia, weakness, anorexia, cachexia and epiphora. The early culling of young animals was more frequently reported by severely affected farms than the analysed farms without clinical signs (71.4% vs. 12.5%, p < 0.001). The geographical area where the farm is located seems to be relevant for the presence of clinical signs of the disease. Ovine anaplasmosis is an emerging disease in Europe that spreads rapidly through tick bites and is capable of causing significant economic losses when it spreads in a naive area and causes an epidemic.