Looking for prognosticators in ovine anaplasmosis: discriminant analysis of clinical and haematological parameters in lambs belonging to differently susceptible breeds experimentally infected with Anaplasma ovis (original) (raw)
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Acta Veterinaria Scandinavica, 2011
Background: It has been questioned if the old native Norwegian sheep breed, Old Norse Sheep (also called Norwegian Feral Sheep), normally distributed on coastal areas where ticks are abundant, is more protected against tick-borne infections than other Norwegian breeds due to a continuously high selection pressure on pasture. The aim of the present study was to test this hypothesis in an experimental infection study. Methods: Five-months-old lambs of two Norwegian sheep breeds, Norwegian White (NW) sheep and Old Norse (ON) sheep, were experimentally infected with a 16S rRNA genetic variant of Anaplasma phagocytophilum (similar to GenBank accession number M73220). The experiment was repeated for two subsequent years, 2008 and 2009, with the use of 16 lambs of each breed annually. Ten lambs of each breed were inoculated intravenously each year with 0.4 ml A. phagocytophilum-infected blood containing approximately 0.5 × 10 6 infected neutrophils/ml. Six lambs of each breed were used as uninfected controls. Half of the primary inoculated lambs in each breed were re-challenged with the same infectious dose at nine (2008) and twelve (2009) weeks after the first challenge. The clinical, haematological and serological responses to A. phagocytophilum infection were compared in the two sheep breeds. Results: The present study indicates a difference in fever response and infection rate between breeds of Norwegian sheep after experimental infection with A. phagocytophilum. Conclusion: Although clinical response seems to be less in ON-lambs compared to NW-lambs, further studies including more animals are needed to evaluate if the ON-breed is more protected against tick-borne infections than other Norwegian breeds.
Pathogens
We conducted a 5-month-long screening of Anaplasma spp. and Anaplasma ovis infection in sheep from central Tunisia. During this longitudinal study, we investigated the infection dynamics using both direct and indirect assessments validated with a polymerase chain reaction (PCR) as the gold standard method. The experimental design included 84 male lambs aged from 6 to 8 months, and 32 ewes, both chosen randomly from June to November with a periodicity of 2 weeks approximately between June and September, and 1 month between September and November. A total of 9 field visits were carried out in this period during which animals were clinically examined and biological samples were extracted. Thus, a total of 716 blood smears, 698 sera from the nine sampling dates, as well as 220 blood samples from the first and the ninth sampling dates were collected from apparently healthy lambs and ewes, respectively, and analyzed by competitive enzyme-linked immunosorbent assay (cELISA) and polymerase ...
Tropical animal health and production, 2010
Anaplasma species are transmitted by ticks and cause diseases in humans and animals. These pathogens infect sheep, an economically important domestic animal worldwide. The current study was designed to characterize in 200 animals the infection with Anaplasma phagocytophilum and Anaplasma ovis and the genetic diversity of A. ovis strains collected from a naturally infected sheep flock with poor health condition. Sheep had 98% seroprevalence to Anaplasma spp. antibodies. PCR results confirmed the presence of A. phagocytophilum and A. ovis DNA in 11.5% and 37% of the sheep, respectively. Concurrent infections were detected in 6.5% of the sheep. Seventy-one adult ticks were collected from 45 sheep with infestations ranging from one to 15 ticks per animal. The analysis of A. ovis msp4 sequences demonstrated a previously unreported polymorphism for this pathogen with 17 different haplotypes in infected sheep. These results demonstrated that, although A. ovis msp4 haplotypes may be less variable when compared with Anaplasma marginale and A. phagocytophilum strains on a global scale, genetic polymorphisms occur in this locus in strains obtained from an infected sheep flock with poor health condition.
Iranian Journal of Veterinary Medicine, 2015
BACKGROUND: Ovine anaplasmosis and theileriosis are important tick-borne diseases of sheep and goats which are distributed in the tropical and subtropical areas of the world. OBJECTIVES: This study was performed to assess hematological status in sheep naturally infected with Anaplasma and Theileria spp. to clarify the pathogenic aspects of various species involved in ovine anaplasmosis and theileriosis in Ahvaz region. METHODS: 109 sheep were sampled, and blood parasite infections were diagnosed by microscopic examination and PCR. The blood samples were also subjected to hematologic assessment. RESULTS: PCR analysis revealed A. ovis infection in 86.2% of sheep, while mixed infections with A. marginale were also detected in 53.2% of them. However, Anaplasma inclusion bodies were only observed in 32.1% of the tested animals. T. ovis were found in 88% of the inspected sheep by PCR, and 67.8% of them were detected microscopically, as well. Hematologic assessment showed that mean RBC, PC...
Immunohistochemical diagnosis of infectious diseases of sheep
Small Ruminant Research, 2010
a b s t r a c t Immunohistochemistry (IHC) is a highly specific and sensitive technique which is now available to aid in the confirmation of diagnosis of many diseases of sheep. When available for use on formalin fixed, paraffin wax-embedded tissue samples, it can be used widely for prospective cases as well as on retrospective studies on archive material. However, for each disease it is vital to select the most appropriate tissue organ samples, to fix them correctly and to be aware of potential limitations of each individual immunohistochemical methodology. In this paper we present a review of many of the diseases of sheep for which specific IHC has been reported including the sources of the reagents and technical aspects of the methodologies.
Hematologic and Clinical Aspects of Experimental Ovine Anaplasmosis Caused by Anaplasma ovis in Iran
Iranian journal of parasitology, 2012
Anaplasma ovis infections can cause clinical symptoms in acute phase and lead to huge economic losses in flocks. The aim of the present study was to investigate the hematological and parasitological changes in experimental anaplasmosis in sheep with Iranian strain of A. ovis. Five male sheep without any blood parasite infection were selected. One hundred ml heparinized blood was collected from splenectomised sheep that showed 6% A. ovis parasitemia. Inoculums of 20 ml blood were administered intravenously to each test animal. Hematological, parasitological and clinical changes of experimental anaplasmosis were studied in 0-38 days post infection. Parasitemia was detected 3 days post infection and reached its maximum level on the day 12 of experiment in test animals. Then the parasitemia was declined, but the organism could be found persistently until the last day of study. The red cell counts, packed cell volume and hemoglobin concentration were decreased and mean corpuscular volume...
First molecular identification and genetic characterization of Anaplasma ovis in sheep from Tunisia
The aims of this study consist of first estimating the molecular prevalence of Anaplasma ovis with specific species loop-mediated isothermal amplification (LAMP) method in sheep (n = 204) from Northern and Central Tunisia. This study also characterizes the genotypes of this Anaplasma species by partial msp4 gene sequence. The molecular prevalence of A. ovis used to record 70.1%. Prevalence rate was significantly higher in El Alia locality (governorate of Bizerte, Northern Tunisia), where it indicated 91.1%, than in Sbikha locality (governorate of Kairouan, Central Tunisia), where it indicated 49.5%. In Sbikha, A. ovis prevalence varied significantly according to two factors, i.e., gender and age. In fact, ewes were significantly more infected than ram lambs. Ticks collected on animals allowed recovering 271 ixodid ticks from El Alia. Ticks belonged to 3 species of Rhipicephalus genus: first, R. turanicus (59.78%) which was the dominant species and which was followed by R. sanguineus (36.16%) and R. annulatus (4.06%). In Sbikha, an absence of ticks was noted in all of the examined sheep. The analysis of A. ovis msp4 sequences revealed four different genotypes; two of them were previously described in Italy and two new other genotypes were classified in an independent cluster. The present work is the first published report of A. ovis infection in sheep in Tunisia. The results indicate the presence of A. ovis at a high rate; hence, the need for a survey into the medical and economic impact of the disease, and the identification of vectors of this bacterium in Tunisia must be made.
Prevalence of Anaplasma phagocytophilum infection and effect on lamb growth
Acta Veterinaria Scandinavica, 2011
Background: A major challenge in sheep farming during the grazing season along the coast of southwestern Norway is tick-borne fever (TBF) caused by the bacteria Anaplasma phagocytophilum that is transmitted by the tick Ixodes ricinus. Methods: A study was carried out in 2007 and 2008 to examine the prevalence of A. phagocytophilum infection and effect on weaning weight in lambs. The study included 1208 lambs from farms in Sunndal Ram Circle in Møre and Romsdal County in Mid-Norway, where ticks are frequently observed. All lambs were blood sampled and serum was analyzed by an indirect fluorescent antibody assay (IFA) to determine an antibody status (positive or negative) to A. phagocytophilum infection. Weight and weight gain and possible effect of infection were analyzed using ANOVA and the MIXED procedure in SAS. Results: The overall prevalence of infection with A. phagocytophilum was 55%. A lower weaning weight of 3% (1.34 kg, p < 0.01) was estimated in lambs seropositive to an A. phagocytophilum infection compared to seronegative lambs at an average age of 137 days. Conclusions: The results show that A. phagocytophilum infection has an effect on lamb weight gain. The study also support previous findings that A. phagocytophilum infection is widespread in areas where ticks are prevalent, even in flocks treated prophylactic with acaricides.
Veterinary World, 2020
Background and Aim: Anaplasma infection is a worldwide prevalent condition that causes significant economic losses in affected flocks. This study was conducted to determine the prevalence and clinical signs associated with ovine anaplasmosis as well as the hematological and biochemical changes associated with the disease in natural infection in North Iraq. Materials and Methods: A total of 420 sheep were appropriately examined, and the clinical signs were documented accordingly. Blood samples were collected and subjected to parasitological, hematological, and biochemical analyses. Results: Anaplasma-infected sheep displayed the following clinical signs: Paleness of the mucous membrane, bloody diarrhea, emaciation, pyrexia, jaundice, nasal discharge, coughing, loss of wool, nervous signs, hemoglobinuria, and lacrimation. The prevalence of Anaplasma infection was 66.19%, and female sheep were significantly (p<0.05) more infected than male sheep. The hematological and biochemical parameters were significantly different between Anaplasma-positive and Anaplasma-negative sheep. Conclusion: Anaplasma infection among sheep is a significant concern in North Iraq considering its prevalence, clinical signs, and hematological and biochemical findings, which entirely causes significant debilitating effects on sheep productivity. It is important to pay more attention toward managing tick infestation among sheep to reduce the occurrence of this rickettsial disease for a more robust livestock sector of the Iraqi economy.
The effect of lamb age to a natural Anaplasma phagocytophilum infection
Small Ruminant Research, 2013
Tick-borne fever (TBF) is caused by the bacterium Anaplasma phagocytophilum that is transmitted by the tick Ixodes ricinus, which is a major challenge in sheep farming along the coast of southwestern Norway. Few efficient and sustainable preventive measures are available, but older lambs seem to be more susceptible than younger lambs to an A. phagocytophilum infection. A field experiment was carried out in 2008 and 2009 on two sheep farms with the breed Norwegian White Sheep (NWS). Three treatment groups of lambs on each farm and year were established: 1; lambs ≥3 weeks old when turned out to pasture and born in early spring, 2; lambs ≤1 week old when turned out to pasture and born in late spring, 3; lambs ≥3 weeks old when turned out to pasture and born in late spring. The study included a total of 337 lambs distributed to treatment group 1, 2 and 3 with 116, 111 and 110 lambs respectively. Recordings of tick-counts, rectal temperature, clinical symptoms and mortality together with weight, blood serology and blood smears were used to analyze the effect of age of lambs to a natural A. phagocytohpilum infection. Gompertz weight curve parameters were estimated for all lambs and were used to compare weight gain in lambs between the treatment groups. There were observations of tick-bites, clinical disease (including fever) and mortality, but no significant effect of lamb age to a natural A. phagocytophilum infection was detected. However, lambs infected with A. phagocytophilum in group 2 had higher (P < 0.05) maximum spring growth rate (358 g/day) than infected lambs in group 1 (334 g/day) and group 3 (310 g/day). Further, lambs not infected with A. phagocytophilum showed no weight differences (P < 0.05) between treatment group 2, compared to groups 1 and 3. Pasturing of ≤1 week old lambs on tick-infested pastures in tick endemic areas, can therefore be recommended to prevent weight loss due to an A. phagocytophilum infection. Note should however be taken on annual and seasonal variations in tick activity relative to lambing, different genetic variants of A. phagocytophilum involved and turnout time as these factors probably will influence the effect of pasturing young lambs.