attempts to transmit Anaplasma marginale to cattle with field collections of Hippobosca rufipes were unsuccessful, 1 of 3 attempts to transmit organism with Stomoxys calcitrans was successful

Bovine anaplasmosis is one of the most important diseases that threaten livestock production worldwide especially in developing countries, in cattle mainly caused by obligate intra-erythrocytic Anaplasma marginale. A. marginale is transmitted biologically by ticks (Hyalomma, Rhipicephalus). Bovine anaplasmosis causes mild to severe clinical signs ranging from anorexia, fever, anemia, and respiratory manifestations to icterus and death. Molecular detection is the best method for Anaplasma diagnosis because of its ability to detect sub-clinical and carrier hosts. This study investigated the occurrence of A. marginale infection among cattle in the Qena governorate utilizing a molecular assay based the msp5 gene. A total of 100 whole blood samples were collected randomly from apparently healthy and diseased cattle. Such cattle were examined clinically, and their samples were included for microscopic examination. PCR screening of the tested cattle showed 23% (23/100) as a positive rate. While 6 samples from 100 (6%) showed A. marginale parasite in the microscopic examination. Several risk factors were analyzed in the current study, higher incidence rates were detected in animals less than 2 years than older than 2 years, Holstein-Friesian breeds than crossbreeds and in animals kept in small farms than in the mass farming system. Clinical and hematological variables were also investigated in several infected and non-infected cattle based on PCR reactivity. Fever, anorexia, respiratory manifestations, enlarged lymph nodes, pale or icteric mucous membranes and digestive disorders were reported in infected cattle (n= 23) but not in non-infected animals (n=77). Consistently, hematological variables in infected cattle (n = 10) revealed significantly lower RBCs count and hemoglobin content than those in the non-infected group (n=20) indicating hemolytic anemia. This study shows the high prevalence of A. marginale in cattle in Qena governorate associated with health hazards and multi-risk factors, so frequent usage of acaricides, regular examination of cattle, and successful chemoprophylaxis are recommended.

Bovine anaplasmosis is the disease caused by the bacterium Anaplasma marginale. It can cause production loss and death in cattle and bison. This was a reportable disease in Canada until April 2014. Before then, infected herds were quarantined and culled, removing infected animals. In North America, A. marginale is biologically vectored by hard ticks (Acari: Ixodidae), Dermacentor variabilis and D. andersoni. Biting flies, particularly horse flies (Diptera: Tabanidae), can also act as mechanical vectors. An outbreak of bovine anaplasmosis, consisting of 14 herds, was detected in southern Manitoba in 2008. This outbreak lasted multiple rounds of testing and culling before eradication in 2011, suggesting local maintenance of the pathogen was occurring. We applied novel approaches to examine the vector ecology of this disease in this region. We did not detect A. marginale by screening of 2056 D. variabilis (2011 and 2012) and 520 horse flies (2011) using polymerase chain reaction (PCR).

The 1-host tick Boophilus annulatus was found to transmit anaplasmosis in cattle transstadially. Anaplasma marginale was invariably transmitted when ticks that had been pulled off Anaplasma-infected calves either after 7 days (as fully engorged larvae) or after 14 to 15 days (as fully engorged nymphs) were transferred within 4 days to susceptible calves. Three morphologically different A marginale isolates, 1 round (tailless) and 2 with different types of appendages (tailed) were transmitted by the ticks. These findings might explain the overlap of the geographic distribution of the disease and that of Boophilus spp in some areas of the world.

The ionophore A23187 was used to facilitate release and continued development of Anaplasma marginale in short-term erythrocyte cultures. Addition of 10 micromolar A23187 to the cultures resulted in significant decrease in percentage of parasitized erythrocytes (PPE) by 24 hours after treatment; further development and increase in PPE was not observed. In contrast, the PPE of untreated cultures, those treated with dimethyl sulfoxide (DMSO) only and with 1 micromolar A23187 increased slightly during that time. Total erythrocyte count decreased in treated cultures in excess of that expected after samples of the medium were taken for analysis. The greatest cell loss and increased hemoglobin concentration in culture medium was observed in cultures treated with 10 micromolar A23187 and with an equivalent volume of DMSO. The DMSO appeared to cause hemolysis of some erythrocytes, but not of infected cells selectively. Release of A. marginale inclusion bodies was seen by electron microscopy in samples from the 10 micromolar A23187-exposed cultures. At 30 minutes after treatment, free initial bodies were frequently seen. Inclusion body membranes and individual A. marginale were associated with membranes of adjacent erythrocytes. Individual rickettsiae were seen in cell depressions and appeared to be entering erythrocytes. However, neither further invasion nor development of the parasite in erythrocytes was observed. Ionophore A23187 appeared to promote release of A. marginale from erythrocytes, but did not enhance infection of erythrocytes or development of organisms in vitro.

Three available differential stains, Camco-Quik, Diff-Quik, and Wright-Giesma were compared for detection of intraerythrocytic Anaplasma marginale in bovine blood smears. In samples where < 1% to more than 51% of the RBC were infected, statistical analysis of the data indicated no significant difference in the detection of A marginale with Camco-Quik or Diff-quik stains. However, a significantly lower percentage of infected RBC were detected when blood smears were stained with the Wright-Giemsa stain, compared with the other 2 methods.

The infectivity and immunogenicity of Anaplasma marginale grown in a tick cell culture from embryonic Dermacentor variabilis ticks were assessed in splenectomized and intact calves, respectively. Culture 1 consisted of the cell line inoculated with midguts of adult ticks infected with the Mississippi isolate of A marginale and dissected 5 to 10 days after repletion and detachment from an experimentally infected calf. Cultures 2 and 3 consisted of the cell line inoculated with midguts of ticks infected with the Virginia isolate of the organism. Inoculum for culture 2 was derived from nymphal ticks dissected 5 to 10 days after repletion and detachment from the infected calf; inoculum for culture 3 was midguts from adult ticks that were fed as nymphs, allowed to molt in the laboratory and dissected 21 to 24 days after molting. In trial 1, cultures 1, 2, and 3 were maintained at pH 6.9 and incubated at 28 C; in trial 2, cultures 1 and 3 were maintained at pH 7.4 and incubated at either 28 C or 37 C. Cultures 1, 2, and 3 failed to induce infection when injected IV and SC into 6 calves in 2 separate trials. Prechallenge sera from these calves reacted with 2 purified Anaplasma antigens in the ELISA, but failed to react in the complement-fixation test. Results of a trial to use cultures 1 and 3 in combination with an oil-in-water adjuvant to immunize intact calves against A marginale were inconclusive. However, prechallenge sera from immunized calves reacted with the 2 purified Anaplasma initial body antigens in the ELISA but failed to react in the complement-fixation text. When reacted against electrophoretically separated A marginale initial body proteins disrupted by sodium dodecyl sulfate, prechallenge serums from calves used in infectivity and immunization trials reacted with a majority of the antigens precipitated by an animal experimentally infected by inoculation of infected blood. This offers additional evidence that A marginale was maintained in the tick culture for up to 11 months and that the organism in culture antigens similar, if not identical, to the erythrocytic stage of the rickettsial agent. The importance of the laboratory culture of A marginale is discussed.

Blood protozoan diseases are significant to animal breeding as theyresult in economic loss due to mortality, reduction in production efficiency and increment in drugs usage. This historical retrospective study was carried out to investigate the most significant blood protozoan diseases, their trends as well as the host range diagnosed by Veterinary Research Institute (VRI) from 1931 to 2010 among Malaysian domestic animals. Conventional techniques such as stained thin blood film, whole blood buffy coatexamination and direct wet smears were utilised for diagnosis from 1931 to 2010. Five most common significant blood protozoan diseases from the domestic animals were identified namely, theileriosis,leucocy tozoonosis, pla smod ia sis, babesiosis and trypanosomiasisrespectively. The setting up of a systematic laboratory service in VRI has enabled more cases of blood protozoan infections to be diagnosed and this has inadvertently led to better understanding and control of the diseases thereby improving the livelihood and reducing economic loss of local farmers.

Objective: This study was designed to determine the molecular prevalence of hemoparasites and their associations with Mafriwal cattle&apos;s age groups. Materials and Methods: Blood samples were taken from the coccygeal veins of calves (n = 92), yearlings (n = 95), lactating (n = 90), and dry (n = 94) cows, which were subjected to microscopic and molecular identification of hemoparasites. The prevalence rate was determined based on the proportion of infected samples in the observed samples. Associations between hemoparasitism and different age groups of Mafriwal cattle were determined by the odds ratio and Fisher&apos;s exact test. Results: Babesia bigemina was the most prevalent hemoparasite in monospecies infection (20.8%), while the co-infection of Anaplasma marginale and B. bigemina (36.4%) had the highest molecular prevalence. Highly significant associations of hemoparasitism were observed between calves and yearlings (p &lt; 0.001, Odds ratio = 21.340, 95% CI = 3.200–907.871), lactating (p &lt; 0.01, Odds ratio = 6.600, 95% CI = 1.808–36.516), and dry (p &lt; 0.001, Odds ratio = 10.457, 95% CI = 2.363–96.242) cows. Nevertheless, calves and yearlings were 2–4 times more likely to be co-in¬fected with multiple hemoparasite species in comparison to older age groups. Conclusion: Mafriwal cattle were more susceptible to hemoparasitism with advancing age, but the younger calves were more prone to be co-infected with multiple hemoparasite species. [J Adv Vet Anim Res 2024; 11(2.000): 384-391]

<p>The spread-smear technique using a drop of blood clot and stained by diluted and undimitcd Giemsa stain was evaluated for the search of blood cell types and recognition of Babesia bovis, Babesia bigemina and Anaplasma marginale hemoparasites. The blood clot samples were taken from a 6 month-old calf experimentally inoculated with the blood from a Cattle Tick Fever carrier. The Technique was sumitable for the observation of different blood cells and for the recognition of the hemoparasites.</p> | <p>O desempenho da técnica de distensão de Gota de Coágulo de sangue, entre as colorações de Giemsa diluído e puro, é avaliado em relação à possibilidade de observação dos elementos figurados e da presença de Babesia bovis, Babesia bigemina e Anaplasma marginale. Utilizou-se um bovino, com 6 meses de idade inoculado com os agentes da Tristeza Parasitária, como doador das amostras de sangue. A técnica permitiu a observação dos eritrócitos, leucócitos e dos hemoparasitas.</p>