Molecular prevalence, characterization and associated risk factors of Anaplasma spp. and Theileria spp. in small ruminants in Northern Pakistan

This study was conducted in four districts (Malakand, Swat, Bajaur and Shangla) of Northern Pakistan to investigate the prevalence, associated risk factors and phylogenetic analyses of Theileria and Anaplasma species in small ruminants. A total of 800 blood samples, 200 from each district, were collected from apparently healthy animals. PCR assays were performed using generic primers for Anaplasma spp. and Theileria spp. as well as species specific primers for A. ovis and T. ovis. Overall infection prevalence was 361/800 (45.1%). Theileria spp. infection prevalence (187/800, 23.3%) was higher than Anaplasma spp. (174/800, 21.7%). Amplified partial 18S rRNA genes were sequenced and enrolled animals were found to be infected by T. ovis (115/800, 14.3%), and at least two more Theileria species (72/800, 9%) were present (T. lestoquardi and T. annulata). All blood samples that were found to be positive for Anaplasma spp. were also positive for A. ovis. Infection prevalence was higher in sheep (227/361, 28.3%) compared to goats (134/361, 16.6%) (p < 0.005). Univariable analysis of risk factors showed that host, age, grazing system and acaricide treatment were significant determinants (p < 0.05) for both Theileria and Anaplasma infections. Multivariable analysis revealed that host, sex, age, tick infestation and grazing system were significant risk factors (p < 0.005) for both pathogens. Phylogenetic analysis revealed variants among the A. ovis and T. annulata samples analysed, indicating that different genotypes are circulating in the field while T. ovis presented the same genotype for the samples analysed.

Serological survey of vector-borne pathogens in stray dogs from Sofia area, Bulgaria

Vector-borne diseases represent a significant part of canine infectious pathology posing serious zoonotic potential. Stray dogs are found to be an important health and ecological factor in urban areas. The objectives of the present study were to update the current knowledge on the seroprevalence of Anaplasma phagocytophilum/ Anaplasma platys, Ehrlichia canis, Borrelia burgdorferi and Dirofilaria immitis in stray dogs from Sofia, Bulgaria. A total of 448 apparently healthy and randomly selected dogs were tested with Anigen Rapid CaniV-4 Test Kit. Overall 28.57% (128/448) of all tested animals were positive for one or more of the pathogenic species. Total percentage was distributed as follows (single plus mix infections): Anaplasma spp. - 16.29% (73/448), D. immitis - 13.39% (60/448), Ehrlichia spp. - 1.34% (6/448) and B.burgdorferi - 0.67% (3/448). The current study demonstrated the circulation of Anaplasma spp. and D. immitis among stray dogs in Sofia, Bulgaria.

Molecular investigation of Anaplasma species in sheep from Heilongjiang Province, northeast China identified four Anaplasma species and a novel genotype of Anaplasma capra

Anaplasmosis poses a great threat to the livestock industry and human health in most tropical and subtropical regions of the world. This study investigated the presence of Anaplasma in sheep from Heilongjiang Province, northeastern China. A total of 341 blood samples were detected by PCR with species-specific primers based on the msp4 gene of Anaplasma ovis, 16S rRNA gene of Anaplasma phagocytophilum and Anaplasma bovis and gltA gene of Anaplasma capra. The results showed that Anaplasma infection was found in 103 (30.2%) of 341 sheep. The infection rates were 2.6%, 8.8%, 15.8% and 10.0% for A. ovis, A. phagocytophilum, A. bovis and A. capra in sheep, respectively. Co-infection involving two Anaplasma species was found in 25 sheep (8.0%), which were usually A. phagocytophilum and A. bovis (72.0%). Co-infection involving A. phagocytophilum, A. capra, A. ovis with zoonotic potential, was found in one sheep. Sequence analysis revealed that the isolates of A. ovis, A. bovis and A. phagocytophilum identified in sheep were closely related to those previously reported in ticks and other animal hosts. Phylogenetic analysis showed that A. capra could be classified into two distinct clusters based on the gltA gene and the isolates identified in sheep from this study were clustered in the A. capra genotype II, which was clearly distinct with the human isolates. The findings in this study report four Anaplasma species and a novel A. capra genotype in sheep from northeastern China, and improve our knowledge of Anaplasma, contributing to the control of ovine anaplasmosis.

Molecular epidemiology and risk factors of Anaplasma spp., Babesia spp. and Theileria spp. infection in cattle in Chongqing, China

Tick-borne pathogens (TBPs) seriously affect cattle production and can be economically damaging. The epidemiology of these organisms in the Chongqing municipality of China is not well described. This study aimed to investigate the prevalence and risk factors of TBPs including Anaplasma spp., Babesia spp. and Theileria spp. in cattle in Chongqing municipality. The results showed that 43.48% (150/345) of cattle were infected with at least one TBP, of which single infections were detected in 104 (30.14%), double infections in 34 cattle (9.86%) and triple infections in 12 (3.48%) of the cattle. The overall prevalence of Anaplasma spp., Theileria spp. and B. bigemina were 22.32%, 23.19% and 7.24%, respectively. Among these, the prevalence of A. bovis, A. central, A. phagocytophilum, A. platys, A. marginale, T. sinensisi and T. orientalis were 8.41%, 7.83%, 4.93%, 4.35%, 2.61%, 22.32% and 2.60%, respectively. We could not detect B. bovis, T. annulata, T. luwenshuni or T. uilenbergi in cattle. Cattle ≥1-year-old were more likely to be infected with Theileria spp. [adjusted odd ratio (AOR) = 2.70, 95% CI = 1.12-6.56)] compared with younger cattle, while cattle ≥1-year-old had reduced susceptibility to B. bigemina (AOR = 0.14, 95% CI = 0.03-0.60). Cattle living at higher altitude (≥500 m) were more susceptible to B. bigemina (AOR = 6.97, 95% CI = 2.08-23.35) and Theileria spp. infection (AOR = 1.87, 95% CI = 1.06-3.32). The prevalence of Theileria spp. on farms with cats was significantly higher than that without cats (AOR = 2.56, 95% CI = 1.12-5.88). Infection with A. bovis and A. central were significantly associated with A. phagocytophilum infection. Furthermore, there were significant associations between A. bovis and A. central infection, T. sinensisi and A. marginale infection, and B. bigemina and T. orientalis infection. This study provides new data on the prevalence of Anaplasma spp., Babesia spp. and Theileria spp. in cattle in Chongqing, and for the first time we reveal a possible relationship between the afore-mentioned pathogens, which will help in formulating appropriate control strategies for these pathogens in this area.

Repeated cross-sectional study of Trypanosoma cruzi in shelter dogs in Texas, in the context of Dirofilaria immitis and tick-borne pathogen prevalence

BACKGROUND

Vector-borne diseases have an adverse impact on health of dogs, and infected dogs can be sentinels for human infection. Infection with Trypanosoma cruzi, an agent of Chagas disease, causes fatal heart disease in dogs across the southern United States but has been neglected from wide-scale prevalence studies.

OBJECTIVES

To determine the prevalence of exposure to T. cruzi, Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi, and infection with Dirofilaria immitis among dogs in shelters across Texas and to identify risk factors for T. cruzi seropositivity.

ANIMALS

Six hundred and eight dogs.

METHODS

This repeated cross-sectional study was performed by collecting blood from ~30 dogs during each of the 3 visits to 7 shelters. We tested serum for antibodies to T. cruzi using 2 tests in series and for antibodies to Ehrlichia spp., Anaplasma spp., and B. burgdorferi and D. immitis antigen using the IDEXX SNAP 4DX Plus point-of-care test. DNA was extracted from blood clots and tested for T. cruzi DNA and strain type via quantitative polymerase chain reactions (qPCR). We used logistic regression to assess risk factors.

RESULTS

One hundred ten (18.1%) of 608 dogs were seropositive for T. cruzi. Prevalence of exposure to the other vector-borne agents was: Ehrlichia spp. 3.6%; Anaplasma spp. 6.9%; B. burgdorferi 0.2%; and D. immitis infection 16.0%. Six of 559 (1.1%) dogs were qPCR-positive for T. cruzi.

CONCLUSIONS AND CLINICAL IMPORTANCE

T. cruzi seroprevalence was comparable to D. immitis prevalence and higher than seroprevalence of the tick-borne pathogens. T. cruzi is an underrecognized health threat to dogs across Texas and possibly other southern states where triatomine vectors are endemic.

Anaplasma spp. in dogs and owners in north-western Morocco

BACKGROUND

Anaplasma phagocytophilum is an emerging tick-borne zoonotic pathogen of increased interest worldwide which has been detected in northern Africa. Anaplasma platys is also present in this region and could possibly have a zoonotic potential. However, only one recent article reports on the human esposure to A. phagocytophilum in Morocco and no data are available on canine exposure to both bacteria. Therefore, we conducted a cross-sectional epidemiological study aiming to assess both canine and human exposure to Anaplasma spp. in Morocco. A total of 425 dogs (95 urban, 160 rural and 175 working dogs) and 11 dog owners were sampled from four cities of Morocco. Canine blood samples were screened for Anaplasma spp. antibodies by an enzyme-linked immunosorbent assay (ELISA) and for A. phagocytophilum and A. platys DNA by a real-time polymerase chain reaction (RT-PCR) targeting the msp2 gene. Human sera were tested for specific A. phagocytophilum immunoglobulin G (IgG) using a commercial immunofluorescence assay (IFA) kit.

RESULTS

Anaplasma spp. antibodies and A. platys DNA were detected in 21.9 and 7.5% of the dogs, respectively. Anaplasma phagocytophilum DNA was not amplified. Anaplasma platys DNA was significantly more frequently amplified for working dogs. No statistically significant differences in the prevalence of Anaplasma spp. antibodies or A. platys DNA detection were observed between sexes, age classes or in relation to exposure to ticks. A total of 348 Rhipicephalus sanguineus (sensu lato) ticks were removed from 35 urban and working dogs. The majority of dog owners (7/10) were seroreactive to A. phagoyctophilum IgG (one sample was excluded because of hemolysis).

CONCLUSIONS

This study demonstrates the occurrence of Anaplasma spp. exposure and A. platys infection in dogs, and A. phagocytophilum exposure in humans in Morocco.

Epidemiological study of common diseases and their risk factors in camels in South Punjab, Pakistan

Bacteriological study of mastitis along with common blood protozoan diseases were studied in dromedary camels in Cholistan, Dera Ismail Khan and Rahim Yar Khan districts in South Punjab, Pakistan. For this purpose 300 camels were sampled randomly at different common grazing and watering point. For study of blood parasites clinically suspected and apparently healthy camels, 150 each, were sampled. An overall prevalence of 15%and 5% was recorded for trypanosomiasis and Anaplasmosis respectively. Trypanosoma evansi was identified with 280 bp product on polymerase chain reaction test. There was significant (P < 0.05) decline in the values of total erythrocyte counts, hemoglobin concentration, packed cell volume, serum total proteins and albumin while erythrocyte sedimentation rate was increased in infected camels as compared to healthy ones. Aspartate aminotransferase, alanine aminotransferase, gamma glutamyltransferase and alkaline phosphatase were also significantly increased in blood protozoan the infected animals. Milk samples for bacteriology were collected from healthy lactating camels (n = 100). Information about different risk factors were gathered on designed performa. Subclinical mastitis on surf field test was recorded in 42% camels while 2% cases of clinical mastitis were recorded. Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Bacillus cereus and. Corynebacterium kutscheri were isolated with characteristic beta and alpha hemolysis patterns. Chi-square analysis showed significant difference as p < 0.05 among various species of bacteria (χ2 = 21.649, P-Value = 0.0001, df = 3). Antibiogram showed Gentamicin, Norfloxacin, Oxytetracycline as most effective therapy for mastitis in camel.

Countrywide serological evaluation of canine prevalence for Anaplasma spp., Borrelia burgdorferi (sensu lato), Dirofilaria immitis and Ehrlichia canis in Mexico

BACKGROUND

Canine vector-borne diseases (CVBD) have become a major concern for canine and human public health. The aim of the study described here is to add epidemiological data regarding four pathogens responsible for CVBD, namely anaplasmosis, borreliosis, dirofilariosis and ehrlichiosis in a national survey conducted in Mexico.

METHODS

Seventy-four veterinary centres located in 21 federal Mexican states were asked to test dogs with clinical signs suspect for CVBD and healthy dogs, for detection of Dirofilaria immitis antigen and antibodies against Anaplasma spp., Borrelia burgdorferi (sensu lato) and Ehrlichia canis using the SNAP® 4DX® from IDEXX® Laboratories.

RESULTS

A total of 1706 dogs were tested, including 943 apparently healthy and 722 CVBD-suspect dogs. Infected dogs were 36.7 %. The highest percentages of infection with E. canis (51.0 %) and Anaplasma spp. (16.4 %) were obtained in the northwestern region, while D. immitis was most frequently found in the northeastern region of the country (8.9 %). Four dogs from the northwestern, northeastern, eastern and southeastern regions, respectively, were positive for B. burgdorferi (sensu lato). Northcentral regions showed lowest overall prevalence of infection (2.4 %). Co-infections were detected in 8.8 % of the dogs tested. Statistically significant lower positivity was found among dogs aged less than one year (23.2 %) and small-sized dogs (27.6 %), while higher prevalence of infection was found in dogs living outdoors (42.0 %), dogs with detectable tick infestation (43.3 %) and dogs that received treatment for tick-transmitted infections (58.8 %). Seropositivity was a risk factor for the presence of clinical signs as follows: Anaplasma spp. (OR = 2.63; 95 % CI: 1.88-3.67; P < 0.0001), D. immitis (OR = 2.52; 95 % CI: 1.61-3.95; P < 0.0001), E. canis (OR = 3.58; 95 % CI: 2.88-4.45; P < 0.0001), mixed infections (OR = 4.08; 95 % CI: 2.79-5.96; P < 0.0001), one or more agents (OR = 3.58; 95 % CI: 2.91-4.42; P < 0.0001).

CONCLUSIONS

Canine serological evidence supports that dogs from Mexico are at risk of acquiring Anaplasma spp., D. immitis and/or E. canis, while B. burgdorferi (sensu lato) transmission is minimal in the country. Practitioners play a fundamental role in the detection and control of these diseases to protect dogs and humans.

Associations between coinfection prevalence of Borrelia lusitaniae, Anaplasma sp., and Rickettsia sp. in hard ticks feeding on reptile hosts

An increasing number of studies reveal that ticks and their hosts are infected with multiple pathogens, suggesting that coinfection might be frequent for both vectors and wild reservoir hosts. Whereas the examination of associations between coinfecting pathogen agents in natural host-vector-pathogen systems is a prerequisite for a better understanding of disease maintenance and transmission, the associations between pathogens within vectors or hosts are seldom explicitly examined. We examined the prevalence of pathogen agents and the patterns of associations between them under natural conditions, using a previously unexamined host-vector-pathogen system--green lizards Lacerta viridis, hard ticks Ixodes ricinus, and Borrelia, Anaplasma, and Rickettsia pathogens. We found that immature ticks infesting a temperate lizard species in Central Europe were infected with multiple pathogens. Considering I. ricinus nymphs and larvae, the prevalence of Anaplasma, Borrelia, and Rickettsia was 13.1% and 8.7%, 12.8% and 1.3%, and 4.5% and 2.7%, respectively. The patterns of pathogen prevalence and observed coinfection rates suggest that the risk of tick infection with one pathogen is not independent of other pathogens. Our results indicate that Anaplasma can play a role in suppressing the transmission of Borrelia to tick vectors. Overall, however, positive effects of Borrelia on Anaplasma seem to prevail as judged by higher-than-expected Borrelia-Anaplasma coinfection rates.

Assessment of Chromogen Suitability in ELISA for the Detection of Anaplasmosis and Trypanosomosis

Two different ELISAs were routinely performed in our laboratory to detect bovine trypanosomosis and anaplasmosis. The ELISA test for trypanosomosis involved the adsorption of a soluble fraction of parasites as the antigen; and, the ELISA for anaplasmosis was performed with a purified recombinant protein MSP5r adsorbed to the plate. With the purpose of assessing the merit of ABTS and TMB, we compared the absorbance obtained from positive and negative control sera from both assays. The results obtained, suggest that TMB is more adequate for recombinant antigens and that ABTS is preferred when partially purified antigenic extracts are used in the ELISA test.

Spatial and management factors associated with exposure of smallholder dairy cattle in Tanzania to tick-borne pathogens

A cross-sectional study of serum antibody responses of cattle to tick-borne pathogens (Theileria parva, Theileria mutans,Anaplasma marginale, Babesia bigemina and Babesia bovis) was conducted on smallholder dairy farms in Tanga and Iringa Regions of Tanzania. Seroprevalence was highest for T. parva (48% in Iringa and 23% in Tanga) and B. bigemina (43% in Iringa and 27% in Tanga) and lowest for B. bovis (12% in Iringa and 6% in Tanga). We use spatial and non-spatial models, fitted using classical and Bayesian methods, to explore risk factors associated with seroprevalence. These include both fixed effects (age, grazing history and breeding status) and random effects (farm and local spatial effects). In both regions, seroprevalence for all tick-borne pathogens increased significantly with age. Animals pasture grazed in the 3 months prior to the start of the sampling period were significantly more likely to be seropositive for Theileria spp. and Babesia spp. Pasture grazed animals were more likely to be seropositive than zero-grazed animals for A. marginale, but the relationship was weaker than that observed for the other four pathogens. This study did not detect any significant differences in seroprevalence associated with other management-related variables, including the method or frequency of acaricide application. After adjusting for age, there was weak evidence of localised (<5 km) spatial correlation in exposure to some of the tick borne diseases. However, this was small compared with the 'farm-effect', suggesting that risk factors specific to the farm were more important than those common to the local neighbourhood. Many animals were seropositive for more than one pathogen and the correlation between exposure to the different pathogens remained after adjusting for the identified risk factors. Identifying the determinants of exposure to multiple tick-borne pathogens and characterizing local variation in risk will assist in the development of more effective control strategies for smallholder dairy farms.

Comparative study of Anaplasma parasites in tick carrying buffaloes and cattle

A comparative study on the prevalence of Anaplasma parasite was conducted on ticks carrying buffaloes and cattle. Five hundred blood samples of both animals (250 of each) were collected during February, March and April. Thin blood smears on glass slides were made, fixed in 100% methyl alcohol and examined. Microscopic examination revealed that 205 (41%) animals had Anaplasma parasites, out of which 89, 44 and 72 animals had Anaplasma marginale, Anaplasma centrale and mixed infection respectively. Infected buffaloes and cattle were 75 and 130 respectively. The infection in female was 53 and 92 in buffaloes and cattle respectively. Twenty-two and 92 blood samples of male were found positive in buffaloes and cattle respectively. Comparative study revealed that the cattle were 26.82% more susceptible than buffaloes. The parasite prevailing percentage in female of both animals was slightly higher than that of the male. This investigation was aimed at studying the comparative prevalence of Anaplasma parasite in tick carrying buffaloes and cattle.

Anaplasma phagocytophilum in Ixodes ricinus ticks and human granulocytic anaplasmosis seroprevalence among forestry rangers in Białystok region

PURPOSE

Human granulocytic anaplasmosis, former ehrlichiosis, is a tick-borne zoonosis of increasing recognition. The aim of the study was: 1) to assess the prevalence of Anaplasma phagocytophilum infection in Ixodes ricinus ticks collected in recreational forests in Bialystok vicinity, the capital of podlaskie voivodship; 2) to evaluate the prevalence of IgG and IgM antibodies to A. phagocytophilum among forestry rangers from the same region.

RESULTS

Of the 372 ticks examined, 54 (14.5%) yield the positive PCR reaction. The highest prevalence was detected in females, up to 27.8% (37/133), almost one third lower in males--9.2% (13/142), followed by nymphs--4.1% (4/97). Human seropositivity study revealed IgG antibodies against A. phagocytophilum in 9 out of 231 individuals (3.9%). No IgM antibodies were found. Sixty-seven individuals 67/231 (29%) reported erythema migrans. IgM anti-Borrelia burgdorferi antibodies were detected in 32 out of 121 (26.4%) persons tested, IgG--in 43 out of 231 (18.6%).

CONCLUSIONS

The data obtained show relatively low A. phagocytophilum seroreactivity among professionally exposed to tick group of forestry workers despite high A. phagocytophilum infection level in the competent vector--I. ricinus ticks.

Serologic and molecular characterization of Anaplasma species infection in farm animals and ticks from Sicily

Although Anaplasma marginale was known to be endemic in Italy, the diversity of Anaplasma spp. from this area have not been characterized. In this study, the prevalence of Anaplasma spp. antibodies in randomly selected farm animals collected on the island of Sicily was determined by use of a MSP5 cELISA for Anaplasma spp. and an immunofluorescence test specific for Anaplasma phagocytophilum. Genetic variation among strains of Anaplasma spp. from animals and ticks was characterized using the A. marginale msp1alpha and the Anaplasma spp. msp4 genes. Eight species of ticks were collected and tested by PCR. Seropositivity for Anaplasma spp. and A. phagocytophilum was detected in bovine and ovine samples. All the donkeys were seropositive for A. phagocytophilum but not for Anaplasma spp. Four A. marginale genotypes were identified by msp4 sequences from bovine and tick samples. Two new genotypes of Anaplasma ovis were characterized in sheep. The sequences of A. phagocytophilum from three donkeys proved to be identical to the sequence of the MRK equine isolate from California. Six A. marginale genotypes were found in cattle and one tick using the A. marginale msp1alpha sequences. All genotypes had four repeated sequences in the N-terminal portion of the MSP1a, except for one that had five repeats. The Italian strains of A. marginale contained three repeat sequences that were not reported previously. Definition of the diversity of Anaplasma spp. in Sicily reported, herein is fundamental to development of control strategies for A. marginale, A. ovis and A. phagocytophilum in Sicily.

Ticks and tick-borne disease in Guatemalan cattle and horses

Blood samples and ticks were collected from 48 cattle and 74 horses from seven sites in the Peten region of Guatemala. Data on body condition, mucous membrane capillary refill time and tick infestation levels were recorded for each animal in the study. Horses had significantly higher levels of tick infestation than cattle, as well as poorer body condition scores. Seroprevalence of Babesia spp. was 95.8% for B. bovis in cattle, 89.6% for B. bigemina in cattle, and 92.7% for B. equi in horses. Seroprevalence of Anaplasma marginale in cattle was 87.5%, similar to reports in animals from other regions of Central America. This is the first time that A. phagocytophilum has been reported in animals from this region, with overall PCR-prevalence of 27.6% in cattle and horses, and seroprevalence of 28.4% (52% in cattle and 13% in horses). An agent was identified with serological cross-reactivity and close genetic relatedness to Ehrlichia ruminantium, but further testing confirmed that the agent in Guatemalan cows was not the agent of heartwater. Ticks were identified to species with the predominant species identified on cattle as Boophilus microplus and Amblyomma cajennense, while Anocentor nitens and A. cajennense were most commonly found on horses. Prevalence of infection, tick infestation levels, host factors and environmental data were analyzed for association; A. nitens was significantly associated with A. phagocytophilum prevalence by village.

Comparison of three oxytetracycline regimes for the treatment of persistent Anaplasma marginale infections in beef cattle

Anaplasmosis, caused by the tick-borne rickettsia, Anaplasma marginale, is an economically important disease of cattle in the United States and worldwide. Cattle that recover from acute infection become carriers in which low or microscopically undetectable A. marginale rickettsemia persists. Tetracycline antimicrobials are currently the only drug used in the US for treatment of acute anaplasmosis. There are currently no drugs specifically licensed for elimination of persistent infections. This study tested the efficacy of three oxytetracycline treatment regimens to clear A. marginale from cattle that were persistently infected. Forty Angus x Simmental steers, aged 6-12 months were experimentally infected with A. marginale. After the steers recovered from acute infection, seroconverted, and were confirmed infected using nested PCR followed by DNA hybridization, the carrier status of each animal was ascertained by sub-inoculation of blood into a separate, splenectomized Holstein calf. The steers were then blocked by bodyweight and randomly assigned as follows to four treatment groups: Treatment A, 300 mg/ml solution of oxytetracycline (Tetradure LA-300, Merial Canada Inc.) administered at 30 mg/kg, by intramuscular (i.m.) injection on day 0; Treatment B, the same 300 mg/ml solution of oxytetracycline administered at 30 mg/kg, i.m. on day 0 and again on day 5; Treatment C, a 200 mg/ml solution of oxytetracycline (Liquamycin LA-200, Pfizer Animal Health) administered at 22 mg/kg, intravenously (i.v.), q 24 h for 5 days (a treatment dose that corresponds with current Office International des Epizooties (OIE) recommendations for treatment prior to export). The fourth group consisted of untreated infected control cattle. All steers were still nested PCR and cELISA positive at 60 days after treatment. Infection was confirmed by subinoculation of blood into a splenectomized Holstein calf. These results demonstrated that the treatment regimens tested failed to clear A. marginale infections in carrier cattle.

Serological Survey of Babesia bovis and Anaplasma marginale in cattle in Tete Province, Mozambique

A serological survey of bovine babesiosis and anaplasmosis in communal cattle was conducted in the northwestern province of Tete, Mozambique. Blood was collected from cattle ranging from 4 to 15 months old from randomly selected farms from six districts. Thirty-nine per cent of all 478 calves tested in Tete Province were seropositive to the ELISA for Babesia bovis antibodies and 63% of all calves were seropositive in the card agglutination test for Anaplasma marginale. Seroprevalence of B. bovis ranged from 22.8% in Tete City District to 48.1% in Angonia District. For A. marginale, it ranged from 34.4% in Angonia District to 87.3% in Moatize District. The dominant factor affecting seroprevalence for both haemoparasites was district and there was a trend for higher intensity of tick control to be associated with a higher seroprevalence of B. bovis and a lower seroprevalence of A. marginale. The obvious differences were the low prevalence of B. bovis in Tete City Council District and the low prevalence of A. marginale in Angonia District. The levels of exposure to B. bovis seen in our study are well below any that could be considered to be consistent with endemic stability, yet they are sufficiently high to ensure that clinical disease would be a risk. The seroprevalence of A. marginale, however, suggests that endemic stability with respect to this disease could exist in districts other than Angonia. There was no strong and consistent relationship between the intensity of control and the likelihood of seropositivity to either of the diseases.

Anaplasma platys: an improved PCR for its detection in dogs

This study compares two PCR assays for the detection of Anaplasma platys in dog blood using primers based on the A. platys 16S rRNA gene. The first approach utilized a "standard" PCR protocol composed of a "single-step" direct amplification using an Ehrlichia genus-specific primer set. The second assay being a "nested" PCR screen that first involved a universal bacterial primer set that amplified the majority of the 16S rRNA gene, followed by the nested round of PCR using an A. platys-specific primer set. Of the 22 dogs sampled, 10 were found to contain A. platys DNA using both protocols, and an additional two dogs were found positive using the nested technique. An extract of A. platys positive genomic DNA was serially diluted and comparison of sensitivities determined between the nested PCR, and a direct assay using A. platys-specific primers. The nested protocol demonstrated an increased sensitivity by at least 2 orders of magnitude when compared to the direct assay alone. Our results indicated that the nested PCR assay with its increased sensitivity would be useful for experimental research investigations as well as offer the potential for use as a routine test in diagnostic pathology.

A sero-epidemiological survey of blood parasites in cattle in the north-eastern Free State, South Africa

A survey to determine the incidence of parasites in cattle (n = 386) was conducted in the north eastern Free State between August 1999 and July 2000. Giemsa-stained blood smears were negative for blood parasites. A total of 94% of the cattle were sero-positive for Babesia bigemina by indirect fluorescent antibody test while 87% were sero-positive for Anaplasma by enzyme-linked immunosorbent assay. The observation of negative blood smears but high incidence of positive serological results for Anaplasma and Babesia for the same group of cattle indicates that this area is endemic for these diseases but with a stable disease situation. All the animals were sero-negative for B. bovis and this is probably because the tick vector (Boophilus microplus) which transmits the disease is not present in the Free State Province. Two tick species belonging to the family ixodidae were found on cattle, namely Boophilus decoloratus and Rhipicephalus evertsi evertsi. In the present study significant differences in seasonal burdens of B. decoloratus occurred, with the highest infestations recorded from February to June. The presence of R. evertsi evertsi throughout the year without any or with small fluctuations in winter months was observed, with a peak from February to May.

Genetic diversity and molecular phylogeny of Anaplasma marginale isolates from Minas Gerais, Brazil

Anaplasma marginale (Rickettsiales: Anaplasmataceae), a tick-borne pathogen of cattle, is endemic in tropical and subtropical regions of the world, and many isolates of A. marginale may occur in a given geographic area. Phylogenetic relationships have been reported for A. marginale isolates from the US using gene and protein sequences of MSP1a and msp4. These studies demonstrated that msp4 sequences, but not MSP1a DNA or protein sequences, provide phylogeographic information and also that MSP1a sequences are highly heterogeneous among A. marginale populations. However, little information is available on the genetic diversity of A. marginale isolates from other regions of the world. The present study was undertaken to examine genetic variation among 10 isolates of A. marginale obtained from infected cattle in the State of Minas Gerais, Brazil, where A. marginale is endemic. Neighbor-joining analysis of msp4 sequences of Brazilian and New World isolates of A. marginale from Argentina, Mexico and the US provided bootstrap support for a Latin American clade. The sequences of the MSP1a repeats of four Brazilian isolates of A. marginale were compared to sequences of Latin American and US isolates. The MSP1a repeated sequences of Latin American isolates of A. marginale had nine repeat forms, alpha-phi, which have not been reported previously in North American isolates of A. marginale. Furthermore, the repeated forms tau, sigma and mu were only present in the Brazilian isolates. The results demonstrated that the genetic heterogeneity observed among isolates of A. marginale is common in endemic areas, independent of the predominant tick vector and is consistent with previous studies in which msp4 provided phylogeographic information about A. marginale isolates, while MSP1a was found not to be a useful marker for phylogeographic characterization of A. marginale isolates.

Assessment of a low virulence Australian isolate of Anaplasma marginale for pathogenicity, immunogenicity and transmissibility by Boophilus microplus

A 14-year-old cow (Dawn) born and kept in a Boophilus microplus-free region gave birth to a calf, which showed the presence of an Anaplasma marginale infection after splenectomy. The calf's grand dam was from a B. microplus infected area and we assume the infection originated via the transplacental route over two generations. An isolate, prepared from the calf, had similar or lower pathogenicity as Anaplasma centrale, and previously exposed steers were resistant to challenge by four A. marginale field isolates. Two attempts to transmit the isolate using B. microplus were unsuccessful. Our results indicate that Dawn A. marginale may be a useful vaccine in Australia and warrants larger scale validation of its safety and potency locally as well as of the protection it affords against African and New World isolates.

Antigens and alternatives for control of Anaplasma marginale infection in cattle

Anaplasmosis, a tick-borne cattle disease caused by the rickettsia Anaplasma marginale, is endemic in tropical and subtropical areas of the world. The disease causes considerable economic loss to both the dairy and beef industries worldwide. Analyses of 16S rRNA, groESL, and surface proteins have resulted in the recent reclassification of the order Rickettsiales. The genus Anaplasma, of which A. marginale is the type species, now also includes A. bovis, A. platys, and A. phagocytophilum, which were previously known as Ehrlichia bovis, E. platys, and the E. phagocytophila group (which causes human granulocytic ehrlichiosis), respectively. Live and killed vaccines have been used for control of anaplasmosis, and both types of vaccines have advantages and disadvantages. These vaccines have been effective in preventing clinical anaplasmosis in cattle but have not blocked A. marginale infection. Thus, persistently infected cattle serve as a reservoir of infective blood for both mechanical transmission and infection of ticks. Advances in biochemical, immunologic, and molecular technologies during the last decade have been applied to research of A. marginale and related organisms. The recent development of a cell culture system for A. marginale provides a potential source of antigen for the development of improved killed and live vaccines, and the availability of cell culture-derived antigen would eliminate the use of cattle in vaccine production. Increased knowledge of A. marginale antigen repertoires and an improved understanding of bovine cellular and humoral immune responses to A. marginale, combined with the new technologies, should contribute to the development of more effective vaccines for control and prevention of anaplasmosis.

Prevalence of blood parasites in cattle from wilayates of Annaba and El Tarf east Algeria

Between June and September 2002, a preliminary study was conducted to assess the prevalence of blood parasites of cattle in eastern Algeria. Fifty-four bovines of different genotypes were submitted to clinical examination. From each animal, blood smears were made and stained by Giemsa. Four species of parasites, namely Theileria annulata, T. orientalis, Babesia bovis and Anaplasma marginale were encountered. Fifty animals carried single or multiple infections with blood parasites and four were found negative. The rate of single infections (72.3%, n = 39) was almost three times higher than multiple infections (20.3%, n = 11). The high percentage of single infections was recorded with T. annulata (53.7%). However single infection with Anaplasma marginale (7.4 %), B. bovis (5.6%) and T orientalis (5.6%) were very low compared to T. annulata infection. The rates of mixed infection were as follows: T. annulata/A. marginale 9.3%, T. annulata/T. orientalis 5.6%, A. marginale/T. orientalis 3.7% and B. bovis/A. marginale 1.9%.

Overcoming constraints to meeting increased demand for Babesia bigemina vaccine in Australia

Demand for live trivalent tick fever vaccine containing Babesia bovis, Babesia bigemina and Anaplasma centrale produced by the Department of Primary Industries, Queensland, has increased from less than 10,000 doses in 1988 to 500,000 doses in 2001. This paper describes a series of trials aimed at overcoming certain constraints to obtain B. bigemina parasitised erythrocytes (PEs) on a large enough scale from infected splenectomised calves to meet the demand. Passage through a series of splenectomised calves failed to increase the yield per calf but we showed that the dose rate of infected cells could be reduced from the long-time standard of 1x10(7) to 2.5x10(6) without affecting immunogenicity and still leaving a safety margin of at least 50-fold for infectivity. This change quadrupled the potential yield of doses per calf and allowed the DPI to meet the increased demand for B bigemina in vaccine. Due to the high cost and limited availability of suitable, health tested donors, calves previously infected with B. bovis or A. centrale were used to provide B. bigemina organisms but the practice resulted in red cell agglutination in some batches of prepared vaccine. A trial is described where B. bigemina-infected red cells were washed by centrifugation to remove agglutinating antibodies. Washing had no effect on parasite viability and this method is now in routine use in the production of trivalent vaccine.

Demonstration of Anaplasma (Ehrlichia) platys inclusions in peripheral blood platelets of a dog in Japan

A free-roaming dog in Okinawa island showed Anaplasma (Ehrlichia) platys-like inclusions within the platelets of peripheral blood samples. The inclusions were positive in indirect fluorescence test with anti-A. phagocytophila serum. The platelet count of the dog was 170,000 microl(-1). The sequence analysis of the 16S rRNA, citrate synthase and heat shock protein genes of DNA from the infected platelets confirmed that the inclusions were A. platys. This is the first detection of A. platys inclusions in dogs in Japan.

Major surface protein 1a effects tick infection and transmission of Anaplasma marginale

Anaplasma marginale, an ehrlichial pathogen of cattle and wild ruminants, is transmitted biologically by ticks. A developmental cycle of A. marginale occurs in a tick that begins in gut cells followed by infection of salivary glands, which are the site of transmission to cattle. Geographic isolates of A. marginale vary in their ability to be transmitted by ticks. In these experiments we studied transmission of two recent field isolates of A. marginale, an Oklahoma isolate from Wetumka, OK, and a Florida isolate from Okeechobee, FL, by two populations of Dermacentor variabilis males obtained from the same regions. The Florida and Oklahoma tick populations transmitted the Oklahoma isolate, while both tick populations failed to transmit the Florida isolate. Gut and salivary gland infections of A. marginale, as determined by quantitative PCR and microscopy, were detected in ticks exposed to the Oklahoma isolate, while these tissues were not infected in ticks exposed to the Florida isolate. An adhesion-recovery assay was used to study adhesion of the A. marginale major surface protein (MSP) 1a to gut cells from both tick populations and cultured tick cells. We demonstrated that recombinant Escherichia coli expressing Oklahoma MSP1a adhered to cultured and native D. variabilis gut cells, while recombinant E. coli expressing the Florida MSP1a were not adherent to either tick cell population. The MSP1a of the Florida isolate of A. marginale, therefore, was unable to mediate attachment to tick gut cells, thus inhibiting salivary gland infection and transmission to cattle. This is the first report of MSP1a being responsible for effecting infection and transmission of A. marginale by Dermacentor spp. ticks. The mechanism of tick infection and transmission of A. marginale is important in formulating control strategies and development of improved vaccines for anaplasmosis.

Antigenic analysis of Anaplasma marginale grown in bovine erythrocytes co-cultured with bovine endothelial cells

Two monoclonal antibodies (mAbs) for A. marginale were used to test the antigenic integrity of A. marginale grown in vitro in bovine erythrocytes co-cultured with endothelial cells. Both the mAbs reacted in the indirect immunofluorescent antibody test with A. marginale grown in vitro and also detected the antigens in Western immunoblots of SDS-PAGE separated antigens made from A. marginale infected erythrocytes from the cultures. Furthermore, active replication was evident as [35S]-methionine is incorporated by A. marginale present in the second passage of a culture maintained for six weeks as shown by immunoprecipitation of labeled antigens by the mAbs. This indicates that A. marginale grown in the in vitro culture system described previously [Waghela et al., Vet. Parasitol. 73 (1997) 43] maintain antigenic character, and with further development the system can be used for preparing immunogens or diagnostic antigens.

Establishment and characterization of an Oklahoma isolate of Anaplasma marginale in cultured Ixodes scapularis cells

Anaplasma marginale is a tick-borne hemoparasite of cattle worldwide. The Virginia isolate of A. marginale was propagated previously in a cell line derived from embryos of the tick, Ixodes scapularis. The cultured Anaplasma (VA-tc) was passaged continuously for over 4 years and retained its infectivity for cattle and antigenic stability. We report herein the continuous in vitro cultivation of a second isolate of A. marginale derived from a naturally infected cow in Oklahoma (OK-tc). Blood from the infected cow was subinoculated into a splenectomized calf and blood collected at peak parasitemia was frozen, thawed and used as inoculum on confluent tick cell monolayers. Colonies of Anaplasma were apparent in low numbers at 9 days post exposure (PE) and infection in monolayers reached 100% by 4-5 weeks PE. Cultures were passaged by placing supernatant onto fresh tick cell monolayers at a dilution of 1:5 or 1:10. By the third passage development of the OK-tc was similar to that of the VA-tc and a 1:5 dilution resulted in 100% infection in 10-12 days. Inoculation of OK-tc into a splenectomized calf caused clinical anaplasmosis and Dermacentor ticks that fed on this calf transmitted the organism to a second susceptible calf. Major surface proteins (MSPs) 1-5 of the OK-tc were compared with homologous proteins present on VA-tc and the erythrocytic stage of the Oklahoma isolate. The MSPs 1, 2, 4, 5 were conserved on the OK-tc but there was evidence for structural variation in MSP3 between the cultured and erythrocytic stage of Anaplasma. MSP2 and MSP3 were the major proteins recognized by serum from infected cattle. Two-dimensional gels also identified positional differences between VA-tc and OK-tc in MSP2 and MSP3. The OK-tc may have potential to be used as antigen for development of an improved vaccine for anaplasmosis in the South Central United States.

Susceptibility to different tick genera in Gambian N'Dama and Gobra zebu cattle exposed to naturally occurring tick infestations

Tick collection on one side of the body and whole tail was performed weekly over one year on 11 Gambian N'Dama (Bos taurus) and 11 Gobra zebu (Bos indicus) cattle to assess breed susceptibility to naturally occurring ticks. Enzyme-linked immunosorbant assay was also performed to assess the serological prevalence of Anaplasma marginale antigen and Babesia bigemina antibody. Packed red cell volume was measured and liveweight gain was recorded. Significantly higher numbers of Amblyomma variegatum (P < 0.002) and Hyalomma spp. (P < 0.001) were found on Gobra zebu than on N'Dama cattle. The serological prevalence of A. marginale antigen was significantly (P < 0.001) lower in N'Dama breed, whilst no difference in the serological prevalence of B. bigemina antibody was found between N'Dama and Gobra cattle. Packed red cell volume was negatively affected by A. marginale infection in both breeds, but to a lesser extent in N'Dama cattle. Liveweight gain was significantly (P < 0.003) higher in N'Dama in comparison with Gobra cattle during the period of abundance of A. variegatum and Hyalomma spp. adults. The significantly lower burdens of A. variegatum and Hyalomma spp. ticks in Gambian N'Dama in comparison with Gobra zebu cattle confirms previous findings. It also shows a more deleterious effect of ticks and tick-borne diseases on animal production and health in Gobra zebu than in N'Dama cattle. The presence of a tick resistant trait in N'Dama cattle is suggested.

Multiplex polymerase chain reaction based assay for the detection of Babesia bigemina, Babesia bovis and Anaplasma marginale DNA in bovine blood

A highly sensitive polymerase chain reaction (PCR) based method was developed to detect, in the same blood sample, DNA of hemoparasites frequently found together infecting cattle in tropical and subtropical areas. Bovine blood containing equal parasitemias of Babesia bigemina, B. bovis and Anaplasma marginale infected erythrocytes was mixed to standardize the test. Twenty microliters of 10-fold dilutions from the pooled blood sample were resuspended in PCR mixture buffer containing each of the species-specific sets of primers. Group I primers (BiIA/IB, BoF/R and Am9/10) which specifically bind B. bigemina, B. bovis and A. marginale DNA were used to amplify a fragment of DNA from genomic parasite DNA. Group II nested primers (BiIAN/IBN, BoFN/RN and Am11/12) were used to prepare, via incorporation of digoxigenin-11-dUTP by PCR, nonradioactive probes specific for internal sequences present in DNA amplified with Group I primers. Agarose gel electrophoresis and Southern blot hybridization studies showed that by using Group I primers, DNA fragments of 278 bp, 350 bp and 200 bp were specifically amplified in samples containing B. bigemina, B. bovis and A. marginale DNA, respectively. The analytical sensitivity of the multiple PCR test, as evaluated by nucleic acid hybridization with the nonradioactive probe, was 0.00001%, 0.00001% and 0.0001% infected erythrocytes for B. bigemina, B. bovis and A. marginale, respectively. Blood collected from cattle previously inoculated with B. bovis (4 years), A. marginale (2 years) and B. bigemina (1 year) was demonstrated to be latently infected by using the Multiplex PCR test.

Anaplasmosis in Uganda. II. Prevalence of bovine anaplasmosis in Uganda

The prevalence of bovine anaplasmosis was studied in 320 Zebu cattle randomly selected from three regions of Uganda: (Central, Southwestern and Northwestern) using dot-ELISA, Western immunoblotting, rapid card agglutination test (RCAT), capillary tube agglutination test (CAT), complement fixation test (CFT), and parasitological techniques. Dried blood on Whatman filter paper No. 1 was eluted in PBS 0.05% Tween 20 prior to testing at an initial dilution of 1:25. The prevalences of parasitaemia were 25% in the central region, 28% in the southwestern region, and 35% in the northwestern region, and the serological prevalence was lowest in the central region and highest in the northwest. Overall, prevalence rates obtained by dot-ELISA (61.9%) and Western immunoblotting (62.5%) were 1.5 times those obtained by RCAT (41%) and three times those obtained by CAT (22.5%). The overall prevalence rates obtained by dot-ELISA and Western immunoblotting compared favourably with the CFT data. The present data utilizing dried blood on filter papers indicate that there is a high prevalence of anaplasmosis in those regions of Uganda surveyed, and confirm our observations and those of others that collecting blood on filter papers is a suitable technique for large scale screening and for seroepidemiological studies.

Seasonality of natural transmission of bovine anaplasmosis under desert mountain range conditions

Splenectomized cattle and mature, spleen-intact cattle were used as sentinels in a 4-year study to assess the seasonality of naturally transmitted anaplasmosis. Sentinels were exchanged and/or monitored monthly on 4 study areas of desert mountain range land in Idaho, Oregon, and Utah. Acute Anaplasma infections were diagnosed in sentinels every month of the year. Of 44 total infections, 29 (66%) were detected during March through August, the primary arthropod season. From December through February, 8 (18%) of the total 44 Anaplasma infections were diagnosed; the winter tick, Dermacentor albipictus, was the probable disease vector. Susceptible cattle were determined to be at risk throughout the year, and anaplasmosis should be considered as a possible diagnosis in cattle with anemia during any season.

Seroepidemiology of bovine anaplasmosis and babesiosis in Venezuela

The serological prevalence of bovine anaplasmosis and babesiosis in the Centro-Occidental region of Venezuela was determined using the indirect fluorescent antibody (IFA) and latex agglutination (LAT) tests. Anaplasma marginale IFA and LAT prevalence rates were 57.7 and 48.6% respectively for cattle of all ages and breeds. The respective prevalence of IFA activity to B. bigemina and B. bovis was 78.2 and 38.8%. The LAT test specific only for Babesia spp. revealed that 61.4% of the animals tested were serologically positive for Babesia parasites. Anaplasma marginale and B. bigemina organisms were detected in peripheral blood smears of 21.1 and 7.5% respectively of cattle surveyed. A longitudinal survey of antibody activity and incidence of parasitaemia for Anaplasma and Babesia infections was conducted in two groups of calves from their birth to seven months of age. The animals generally experienced infections between three and four months of age the period subsequent to decline in colostral antibody levels. Seroepidemiological data are considered in the formulation of proposed vaccination regimens for anaplasmosis and babesiosis.

The use of tick transmission by Boophilus microplus to isolate pure strains of Babesia bovis, Babesia bigemina and Anaplasma marginale from cattle with mixed infections

Pure strains of Babesia bovis, Babesia bigemina and Anaplasma marginale were isolated from cattle infected with all 3 species as well as Theileria sp. and Eperythrozoon teganodes, using only transmission by the tick, Boophilus microplus. Unengorged adult ticks transferred to susceptible cattle transmitted A. marginale, but not Babesia. Engorged adults gave rise to progeny that transmitted Babesia, B. bovis by larvae and B. bigemina by male ticks. The Theileria and E. teganodes were not transmitted by the ticks and thus did not appear in calves used for isolating the pure strains of Babesia and A. marginale.

In vitro cultivation of Anaplasma marginale: growth pattern and morphologic appearance

Anaplasma marginale propagated in vitro showed an increasing rate of replication in a sequence of three experiments. The changes in the percentage of parasitized erythrocytes and identification of the organism in culture were monitored by the Giemsa-staining and the direct fluorescent antibody techniques. The ultrastructure of the organism in culture also was determined. The percentage of parasitized erythrocytes increased more than three times in the first experiment during a period of 8 days, and about ten times in the second experiment during a period of 14 days. After 8 days of observation of the primary culture in the third experiment, the trend of growth was more rapid than in the first and second experiment. The viability of the organism was verified by inoculation of susceptible calves, using 13- and 33-day cultures of the first and the second experiments, respectively. The primary cultures were subcultured twice by dilution with normal bovine erythrocytes.

Some effects of reduced energy intake on the development of anaplasmosis in Bos indicus cross steers

Some effects of the plane of nutrition on the development of anaplasmosis in Brahman cross steers were investigated. Batches of 39 and 30 Brahman cross steers, aged approximately 27 months were each divided by stratified randomisation into 4 groups of similar mean PCV and body weight. Two similar experiments, designated A and B were conducted. Groups 1 and 2 were fed a ration of lucerne chaff at the rate of 1 M Cal ME/80 kg live weight/day for 8 weeks aimed to reduce body weight by approximately 5 kg/week. Animals in groups 3 and 4 were fed a ration for the same period aimed to increase body weight by approximately 2 kg/week. Groups 1 and 3 were then inoculated with approximately 10(10) Anaplasma marginale infected erythrocytes and the effects of the subsequent infections during the clinical and recovery phases were examined by measuring humoral antibody response, packed cell volume, parasitaemia and body weight. Groups 2 and 4 were uninfected controls. Anaplasmosis, as measured by three responses, was less severe in the starved animals of group 1. Significant differences in packed cell volume and parasitaemia were detected for short periods between the infected groups 1 and 3. Anaplasmosis caused losses of 6.2% and 5.9% in the mean body weight of group 3 animals in experiments A and B respectively. Most of this loss occurred during the clinical phase of the disease. The disease caused no apparent loss of weight in the infected animals of group 1.

Changes in serum concentration of phagocytosis-stimulating factor in experimentally induced bovine anaplasmosis: preliminary findings

To determine whether correlation exists between serum concentration of phagocytosis-stimulating factor (PSF) and in vivo phagocytic activity, 2 splenectomized steers were inoculated with Anaplasma marginale, and their serum PSF concentrations were monitored. At the time of the anemic crisis, serum PSF concentrations were elevated five to tenfold.

Absence of Anaplasma marginale infection in American Bison raised in an anaplasmosis endemic area

Blood was collected at slaughter from 132 adult American bison (Bison bison) raised in an anaplasmosis endemic area where the vector Dermacentor andersoni (equals venustus) is indigenous. Hematologic studies revealed no indication of clinical anaplasmosis. Card agglutination and complement-fixation tests on all bison serums were negative. Eleven anaplasmosis-susceptible calves each inoculated with 204 ml of blood pooled from 12 bison did not develop anaplasmosis. Results of this study indicate American bison have resistance to natural A. marginale infection.