Anaplasma phagocytophilum-a widespread multi-host pathogen with highly adaptive strategies

The bacterium Anaplasma phagocytophilum has for decades been known to cause the disease tick-borne fever (TBF) in domestic ruminants in lxodes ricinus-infested areas in northern Europe. In recent years, the bacterium has been found associated with lxodes-tick species more or less worldwide on the northern hemisphere. A. phagocytophilum has a broad host range and may cause severe disease in several mammalian species, including humans. However, the clinical symptoms vary from subclinical to fatal conditions, and considerable underreporting of clinical incidents is suspected in both human and veterinary medicine. Several variants of A. phagocytophilum have been genetically characterized. Identification and stratification into phylogenetic subfamilies has been based on cell culturing, experimental infections, PCR, and sequencing techniques. However, few genome sequences have been completed so far, thus observations on biological, ecological, and pathological differences between genotypes of the bacterium, have yet to be elucidated by molecular and experimental infection studies. The natural transmission cycles of various A. phagocytophilum variants, the involvement of their respective hosts and vectors involved, in particular the zoonotic potential, have to be unraveled. A. phagocytophilum is able to persist between seasons of tick activity in several mammalian species and movement of hosts and infected ticks on migrating animals or birds may spread the bacterium. In the present review, we focus on the ecology and epidemiology of A. phagocytophilum, especially the role of wildlife in contribution to the spread and sustainability of the infection in domestic livestock and humans

Treatment against helminths in Norwegian sheep: a questionnaire-based survey

A questionnaire was distributed to 5487 farmers throughout Norway in order to obtain information about management practices regarding helminth infections in sheep. In addition, the farmers' perceptions of helminths and anthelmintic efficacy were investigated. Most farmers (80%) treated prophylactically against nematodes, and 24% also used prophylactic treatment against Fasciola hepatica. Overall, few farmers (11%) used parasitological analysis as a tool to assess the timing of treatment, but rather based it on other factors such as previous experience (70%). In the surveyed sheep flocks, the use of benzimidazoles was reduced from 2018 (52%) to 2019 (47%) (p < 0.01), whereas the use of macrocyclic lactones increased from 2017 (23%) to 2019 (36%) (p < 0.001). Poor anthelmintic efficacy was suspected by 10% of the farmers, and 11% reported that helminths were an increasing problem in their flocks. The majority of farmers (72%) considered their veterinarian as the most important advisor for treatment of parasites, but reported a high level of uncertainty regarding which parasites were present in their flocks, with unknown status most frequently reported for Haemonchus contortus (71.5%). This is probably related to the fact that very few farmers (15%) regularly test their animals for parasites. The present study provides up-to-date information on treatment practices for helminths in Norwegian sheep flocks

Anthelmintic resistance in small ruminants in the Nordic-Baltic region

Gastrointestinal nematodes (GIN) in small ruminants result in production losses, and consequently economic losses, and are an animal welfare problem in most countries in the Nordic-Baltic region. Intensive use of anthelmintics to control helminth infections has led to anthelmintic resistance (AR), which has become a major issue in many European countries. Several studies have been performed in countries in the Nordic-Baltic region (e.g. Denmark, Sweden, Norway and Lithuania) showing increasing/emerging levels of AR. The aim of this paper is to provide an overview of the problem of AR on sheep and goat farms in the Nordic-Baltic region. This region has a limited number of registered anthelmintics. However, researchers in this area have discovered some surprising findings, such as ivermectin (IVM) resistance on a farm that had never used IVM. In Sweden there is evidence of macrocyclic lactone (ML)-resistant Haemonchus contortus being introduced with sheep imported from the Netherlands. As elsewhere in the world, the livestock trade appears to be contributing to the spread of AR in the region and isolated cases of multidrug-resistant cases have also been reported. This is surprising given that the frequency of treatments here is much lower than in other countries where sheep production is economically more important. The prevailing nematodes are Haemonchus, Teledorsagia and Trichostrongylus, while on some farms Haemonchus is dominant and clinical haemonchosis has increasingly been observed in recent decades. The reasons for this are unclear, but are probably related to this parasite's propensity to rapidly develop drug resistance and a general lack of awareness of the problem, possibly in combination with global warming and the increased livestock trade within the EU. In addition, domestic interactions through contacts with wildlife ruminants, alpacas may also be a contributing factor for transmission of AR

Variant -and individual dependent nature of persistent Anaplasma phagocytophilum infection

<p>Abstract</p> <p>Background</p> <p><it>Anaplasma phagocytophilum </it>is the causative agent of tick-borne fever in ruminants and human granulocytotropic anaplasmosis (HGA). The bacterium is able to survive for several months in immune-competent sheep by modifying important cellular and humoral defence mechanisms. Little is known about how different strains of <it>A. phagocytophilum </it>propagate in their natural hosts during persistent infection.</p> <p>Methods</p> <p>Two groups of five lambs were infected with each of two <it>16S </it>rRNA gene variants of <it>A. phagocytophilum</it>, i.e. <it>16S </it>variant 1 which is identical to GenBank no <ext-link ext-link-id="M73220" ext-link-type="gen">M73220</ext-link> and <it>16S </it>variant 2 which is identical to GenBank no <ext-link ext-link-id="AF336220" ext-link-type="gen">AF336220</ext-link>, respectively. The lambs were infected intravenously and followed by blood sampling for six months. <it>A. phagocytophilum </it>infection in the peripheral blood was detected by absolute quantitative real-time PCR.</p> <p>Results</p> <p>Both <it>16S </it>rRNA gene variants of <it>A. phagocytophilum </it>established persistent infection for at least six months and showed cyclic bacteraemias, but variant 1 introduced more frequent periods of bacteraemia and higher number of organisms than <it>16S </it>rRNA gene variant 2 in the peripheral blood.</p> <p>Conclusion</p> <p>Organisms were available from blood more or less constantly during the persistent infection and there were individual differences in cyclic activity of <it>A. phagocytophilum </it>in the infected animals. Two <it>16S </it>rRNA gene variants of <it>A. phagocytophilum </it>show differences in cyclic activity during persistent infection in lambs.</p

Occurrence of haemolytic Mannheimia spp. in apparently healthy sheep in Norway

<p>Abstract</p> <p>Background</p> <p>The occurrence of <it>Mannheimia </it>species in healthy sheep has only been investigated to a very limited extend since the genus and its five named species were established. The aim of the present study was to evaluate the occurrence of haemolytic <it>Mannheimia </it>species in apparently healthy sheep originating from four sheep flocks in South-Western Norway.</p> <p>Methods</p> <p>Typical <it>β</it>-haemolytic <it>Pasteurellaceae </it>were isolated from nasal swabs and subsequently subjected to bacteriological examination. A total of 57 <it>Mannheimia </it>isolates were obtained in pure culture. All isolates were genotyped by amplified fragment length polymorphisms (AFLP) analysis and compared to six reference strains. The 16S rRNA gene sequences of two isolates were also determined.</p> <p>Results</p> <p><it>β</it>-haemolytic <it>Mannheimia </it>species were isolated from 24% to 64% of the sheep in the four flocks. A total of 26 haemolytic <it>M. ruminalis</it>-like strains were isolated among which, a considerable genetic diversity was found. Eighteen <it>M. glucosida </it>isolates were obtained from three flocks, whereas <it>M. haemolytica </it>was only isolated from two flocks, 16 of them being from only one of the flocks.</p> <p>Conclusion</p> <p>We demonstrate that a relatively high number of apparently healthy sheep in Norway seem to carry the potentially pathogenic <it>M. haemolytica </it>and <it>M. glucosida </it>in the upper respiratory tract. An unexpectedly high number of haemolytic <it>M. ruminalis</it>-like organisms were also obtained in all four flocks. The usually non-haemolytic <it>M. ruminalis </it>are typically isolated from healthy ruminants. The significance of <it>β</it>-haemolytic <it>M. ruminalis</it>-like organisms is unknown and should be investigated in a future study.</p