Susceptibility of Chinese hamsters (Cricetulus griseus) to the infection of Babesia microti

Chinese hamsters were examined for the susceptibility to the infection with Babesia microti based on the hematological parameters during the course of infection. A marked decrease in the RBC count, Ht value, Hb concentration, and an increase in WBC count due to the development of neutrophils or monocytes were recognized with the progress of parasitemia. Remarkable clinical findings were anemia and persistent infection with a low level of parasite burden in the chronic and convalescent stages. From these findings, it was concluded that Chinese hamsters were susceptible to infection with B. microti and would be useful for infection examination with the parasite.

Vaccination of older Bos taurus bulls against bovine babesiosis

Two separate groups of Bos taurus bulls, one of 106 and the second of 27 animals, imported to Israel from areas free of Babesia bovis and Babesia bigemina, were vaccinated against babesiosis with a bivalent live attenuated vaccine. In light of the fact that routine vaccination is recommended at the weaning age, these bulls--of highly susceptible breeds--were kept under close surveillance to prevent losses that might be caused by severe clinical reactions to their vaccination at the age of 16-18 months. Seven days after vaccination, about one-third of the 106 bulls in the first group developed clinical signs of B. bigemina infection, which peaked at day 9, and then diminished from day 11, when the patent period known for B. bovis infection was observed. Because of the severe clinical responses a total of 36% of the bulls required babesicidal treatment. Despite the treatment Babesia were not sterilized: 33 and 68% of the animals remained PCR positive for B. bigemina and B. bovis, respectively. To mitigate the severe responses to vaccination, the 27 bulls of the second group were vaccinated in two-steps: they were inoculated initially with avirulent culture-derived parasites and then vaccinated with the conventional donor-derived vaccine a month later. None of the bulls in the latter group developed clinical babesiosis, all were serologically positive to B. bigemina, and 67% showed seroconversion to B. bovis. In light of the experience described here, it is suggested that sensitive older cattle be vaccinated against babesiosis by priming them with avirulent in vitro-cultured parasites and then inoculating them with the conventional donor-derived vaccines.

Theileria (Babesia) equi and Babesia caballi Infections in Horses in Galicia, Spain

The control of equine piroplasmosis is becoming increasingly important to maintain the international market open to the horse industry. The purpose of this study was to demonstrate the occurrence of equine piroplasmosis (Theileria equi and Babesia caballi) in Galicia, north-west Spain, and to compare haematological and serum biochemistry parameters between non-parasitaemic horses and horses parasitaemic with T. equi and B. caballi. Sixty serum samples (control group) were taken from healthy horses pastured on two farms, and examined for evidence of equine T. equi and B. caballi infection by indirect fluorescent antibody test (IFAT). Of the 60 samples, 24 (40%) and 17 (28.3%) samples were positive for T. equi and B. caballi, respectively. Twelve (20%) samples were positive for both parasites. Haematology and serum biochemistry were compared between controls and a series of 36 horses clinically affected by T. equi (25) or B. caballi (11). Compared with the healthy group, there was a 43% and 37% decrease in the haematocrit for T. equi and B. caballi infection, respectively. Parasitaemic horses presented an intense anaemia and serum biochemistry signs of liver damage. The anaemia was more severe in T. equi-infected than in B. caballi-infected horses. Our results suggest that equine piroplasmosis is widespread in the region and is a cause for concern.

[Autochthonous babesiosis in dogs in The Netherlands associated with local Dermacentor reticulatus ticks]

In the spring and autumn of 2004, 20 respectively 3 cases of autochthonous canine babesiosis were diagnosed in the Netherlands, four of which ended fatally. Adult Dermacentor reticulatus ticks were found on four dogs. Case descriptions and diagnostics of this B. canis outbreak are discussed in more detail.

Vaccination against canine babesiosis

It has been known for several decades that the soluble parasite antigen (SPA) of several Babesia species can be used as a vaccine against the clinical manifestations of babesiosis. Originally observed in the plasma of infected animals, SPA can also be recovered from the supernatants of in vitro cultures of these parasites. Variable success has been reported for vaccines against the bovine and canine Babesia parasites, which seems to be related to antigenic diversity within Babesia species. In this article, an overview is presented of the development of such vaccines for dogs, and additional research that has led to improvement of an SPA-based vaccine against Babesia canis in dogs.

Immunization with recombinant surface antigen P50 of Babesia gibsoni expressed in insect cells induced parasite growth inhibition in dogs

This is a report of a vaccine trial directed against Babesia gibsoni infection in dogs with the use of the recombinant antigen P50. Dogs immunized with P50 showed partial protection manifested as a significantly low level of parasitemia. The results indicated that P50 is a primary vaccine candidate molecule against canine B. gibsoni infection.

Serodiagnosis of Babesia gibsoni infection in dogs by an improved enzyme-linked immunosorbent assay with recombinant truncated P50

The surface antigen P50 of Babesia gibsoni is an important candidate for the development of a diagnostic reagent for canine piroplasmosis. In order to establish an effective diagnostic method for practical use, the gene encoding truncated P50 (P50t) lacking a signal peptide and C-terminal hydrophobic regions were cloned and expressed in Escherichia coli as a fusion protein with glutathione S-transferase (GST). More than 90% portion of the GST-P50t was expressed as a soluble form, in contrast with GST-P50f (full-length), which was completely expressed as an insoluble form. This result indicates that removal of the hydrophobic signal peptide and C-terminus had dramatically improved its hydrophilicity. The purified GST-P50t was tested in an enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to B. gibsoni in dogs. The ELISA with GST-P50t clearly differentiated between B. gibsoni-infected dog sera and uninfected dog sera. In addition, the ELISA detected no cross-reactivity with sera from dogs experimentally infected with the closely related parasites, B. canis canis, B. canis vogeli, and B. canis rossi. Field serum samples collected from dogs in Japan and China were examined for the diagnosis of B. gibsoni infection by using the ELISA. 14.5% (9/62), 5.8% (7/120), and 5.4% (2/37) of tested samples were positive for dogs from Okinawa, Yamaguchi, and Osaka prefectures, Japan, respectively. On the other hand, 4.8% (2/41) of tested samples were positive for dogs from Nanjing, China. These results suggest that the GST-P50t could be a reliable reagent for practical use in ELISA for the serodiagnosis of canine piroplasmosis caused by B. gibsoni.

Progression towards endemic stability to bovine babesiosis in cattle introduced onto a game ranch

An opportunity to study progression toward endemic stability to Babesia bigemina arose when cattle were reintroduced onto a game ranch in 1999 after an absence of three years. The study was conducted between August 2000 and June 2001. The unvaccinated breeding cows were sampled only once. Calves born during October 1999 were initially vaccinated against B. bigemina and Babesia bovis at the age of 4 months and were then bled at 10, 17 and 20 months of age. Calves born during 2000 were bled at 7 and 8 months of age. Sera were collected from all the cattle sampled and later tested for antibodies against B. bigemina and B. bovis using the indirect fluorescent antibody (IFA) test. Although endemic stability to B. bigemina had not been achieved at Nooitgedacht 2 years after resumption of cattle ranching, the high seroprevalence in the unvaccinated 8-month-old calves suggested that the situation was approaching stability and that calf vaccination against bovine babesiosis was not required. Tick control should therefore be restricted to prevent excessive tick worry. Only vaccinated cattle were positive to B. bovis and it was concluded that the parasite was absent from the ranch.

Incidence and prevalence of tick-borne haemoparasites in domestic ruminants in Ghana

Giemsa-stained thin blood smears prepared monthly from cattle, sheep and goats in the Greater Accra region of Ghana between May 1994 and December 1996 were examined for presence of tick-borne haemoparasites. The majority of animals were less than 2 months old at the start of the survey. Monthly and cumulative incidences are presented of Anaplasma sp., Babesia bigemina, Borrelia sp., Eperythrozoon sp., Theileria mutans and Theileria velifera in cattle, Anaplasma sp., Borrelia sp., and Theileria sp. in sheep, and Anaplasma sp. in goats. T. mutans was the commonest parasite in cattle, with 100% incidence in calves by 10 months of age, and Anaplasma was commonest in small ruminants. The relative prevalence of these haemoparasites in blood smears from cattle, sheep and goats sampled on a single occasion at sites in all 10 regions of Ghana was found to be similar, though actual infection rates were lower. Packed cell volume (PCV) measurements from the sampled animals are also presented; no seasonal trends were evident in the PCV of the cattle, sheep and goats sampled monthly. In animals sampled on a single occasion, mean PCV was significantly higher in cattle and sheep without detectable haemoparasite infection, and in cattle was lowest in animals positive for both Babesia and Anaplasma, while there was no difference in mean PCV levels between parasitised and non-parasitised goats.

Efficacy of atovaquone against Babesia gibsoni in vivo and in vitro

The therapeutic efficacy of atovaquone against Babesia gibsoni was examined in three dogs experimentally infected with B. gibsoni isolated from naturally infected dogs in Aomori Prefecture, Japan. Once parasitemia reached 10%, atovaquone was administered orally (30 mg/kg twice daily for 7 days). Within 2 days of atovaquone treatment, the parasite disappeared from blood smears without any clinical side effects. Anemia and thrombocytopenia were significantly improved in all the dogs. However, a polymerase chain reaction assay revealed that a B. gibsoni marker gene was intermittently present in peripheral blood after atovaquone therapy, indicating that the organism had not been eliminated, and parasites reappeared in blood smears 33 days after the last treatment. To investigate the change in sensitivity against atovaquone, an in vitro sensitivity test was performed using peripheral blood obtained from an untreated dog that was infected with the original parasite isolate, and from two of the experimentally infected and atovaquone-treated animals (blood was collected at the time of the post-treatment recurrence of the B. gibsoni infection). Atovaquone was added to the culture medium to final concentrations of 0.1, 1, 10, 100, and 1000 nM. For the untreated parasites, complete growth inhibition occurred at 1000 nM of atovaquone, whereas the recurrent parasites were inhibited by only 39.52 +/- 8.34% and 31.31 +/- 8.14% at this concentration after 48 h of incubation. Thus, the recurring parasites were less sensitive to atovaquone than the untreated originally isolated parasites.

Feline babesiosis in South Africa: a review

Babesia felis, originally identified in wild cats in the Sudan, was subsequently found to cause clinical disease in domestic cats. Although babesiosis in domestic cats has been reported sporadically from various countries, as a significant disease it appears to be a distinctly South African phenomenon. Apart from an inland focus, feline babesiosis is reported regularly only from coastal regions. The infection is assumed to be tick-borne, but the vector has not been identified. Feline babesiosis tends to be an afebrile, chronic, low-grade disease. The most frequently reported complaints by owners are anorexia and lethargy. The main clinical findings are anemia, depression, and occasionally icterus. Concurrent infections (e.g., Mycoplasma haemofelis, FeLV, FIV) may contribute to the clinical picture. Laboratory findings commonly include regenerative anemia, elevation of alanine transaminase (but not alkaline phosphatase) and total bilirubin concentrations, and a variety of electrolyte disturbances. Secondary immune-mediated hemolytic anemia can be seen occasionally. Drugs effective against other Babesia species give variable and questionable results. The drug of choice is primaquine phosphate, which effects a clinical cure but does not sterilize the infection. Repeated or chronic therapy may be required.

Immune response to Babesia bigemina infection in pregnant cows

The objective of this study was to characterize the immune response of Babesia bigemina-infected cows during the second trimester of pregnancy. Twelve animals were divided into four groups (I, II, III, IV); groups I and II were pregnant cows, groups III and IV were non-pregnant cows. Groups I and III were infected with a virulent strain of Babesia bigemina, the doses utilized was 1 x 10(7) infected red blood cells IM. Groups II and IV were noninfected control groups. All the infected animals were severely affected; at days 5-7 post-inoculation (DPI) they showed clinical signs: fever (40-41.5 degrees C), packed cell volume reduction, and parasitemia, and specific treatment was required. The immune response was monitored daily from 0-11 DPI. As shown by flow cytometry analysis, in infected animals the distribution in peripheral blood of the T-cells subpopulations (CD4+, CD8+, gammadelta T-cells) was not affected when compared to the control groups. By ELISA, IFN-gamma production showed a trend to increase in plasma between 6-10 DPI; noninfected cows showed the lowest optical density values. By RT-PCR, a Th1 predominant response was observed, TNFalpha, INF-gamma and iNOs were detected. In contrast IL-4 and IL-10 were weak or undetected. The results of this trial will be discussed.

Field challenge of cattle vaccinated with a combined Babesia bovis and Babesia bigemina frozen immunogen

To determine the optimal dose of a combined, frozen immunogen containing in vitro culture-derived strains of Babesia bovis and Babesia bigemina, twenty-four 14-month-old Bos taurus steers from a Boophilus microplus-free area in Northern Mexico were used in this experiment. Cattle were randomly allocated into six groups with four animals each, and were intramuscularly inoculated as follows: group 1 (control animals) were administered with normal bovine erythrocytes; group 2 received 1 x 10(7) B. bovis- and B. bigemina-infected erythrocytes as a combined fresh immunogen. Groups 3-6 were inoculated with a combined frozen immunogen containing (previous to cryopreservation at -196 degrees C) 1 x 10(7), 5 x 10(7), 1 x 10(8), and 5 x 10(8) infected erythrocytes of each parasite species, respectively. Four months after immunization, principal and control animals were translocated to a bovine babesiosis endemic zone for field challenge. This was carried out by introducing the experimental cattle to tick-infested pastures for 30 days without ixodicide treatment. Cattle were monitored from day 8 postintroduction to the field (PIF) by recording the manifestation of clinical disease, rectal temperature values (RT), packed cell volume index (PCV), and percent of parasitized erythrocytes (PPE). At challenge, all experimental cattle became infected with both Babesia bovis and B. bigemina. However, except for two animals from group 6, none of the vaccinated animals showed signs of acute clinical babesiosis; therefore, no treatment was instituted. Out of six animals showing acute clinical babesiosis (four group 1 controls and two group 6 vaccinates), two animals (one from each group) died, despite babesiacide treatment, as they manifested classical cerebral babesiosis caused by B. bovis. Regardless of the dose or type of immunogen used (combined fresh or frozen), 90% of vaccinated cattle were determined to be protected against the virulent Babesia sp. field isolates. Nevertheless, by evaluating clinical parameters, such as average of maximum drop in PVC index (28.5%), average duration of parasitemia (3 days for B. bovis; 8.5 days for B. bigemina), and average duration of RT values > or = 39.5 degrees C (2 days), animals receiving 1 x 10(8) infected erythrocytes, as combined frozen immunogen, were more efficaciously protected against challenge with virulent B. bovis and B. bigemina field isolates.

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.

Glucose, lactate, and pyruvate concentrations in dogs with babesiosis

OBJECTIVE

To document changes in glucose, lactate, and pyruvate concentrations in dogs with severe or complicated babesiosis; assess relationships among glucose, lactate, and pyruvate concentrations in those dogs; and compare clinical and laboratory variables in dogs with and without hypoglycemia and hyperlactatemia.

ANIMALS

20 dogs with naturally developing severe or complicated babesiosis.

PROCEDURE

Samples and measurements were obtained before treatment was initiated. Babesiosis was diagnosed by examination of blood smears. Arterial blood pressure measurement, parasite quantification, CBC count, serum biochemical analysis, urinalysis, venous blood gas analysis, and acid-base determination were performed. Glucose, lactate, and pyruvate concentrations were measured in samples of venous blood.

RESULTS

We detected a significant negative correlation between glucose and lactate concentrations. Glucose, lactate, and pyruvate concentrations all differed significantly between dogs that died and those that survived. Three of 5 dogs that died had concurrent hypoglycemia, hyperlactatemia, and hyperpyruvatemia. Hypoglycemic dogs differed significantly from normoglycemic dogs with regard to lactate, urea, and bicarbonate concentrations; lactate-to-pyruvate ratio; percentage parasitemia; and PCO2. Dogs with hyperlactatemia differed significantly from normolactatemic dogs with regard to clinical collapse; alanine transaminase activity; concentrations of bilirubin, urea, creatinine, and bicarbonate; percentage parasitemia; and PCO2.

CONCLUSIONS AND CLINICAL RELEVANCE

Abnormal carbohydrate metabolism is commonly evident in dogs with severe or complicated babesiosis and is often associated with changes in other clinical and laboratory variables. Significant differences were found between survivors and nonsurvivors. Hypoglycemia should be assessed and aggressively treated in dogs with babesiosis. Lactate concentration can be used as an indicator of disease severity.

Babesia canis canis in dogs from Hungary: detection by PCR and sequencing

Canine babesiosis in Hungary has always been a severe and frequent disease, attributed to infection with Babesia canis transmitted by Dermacentor reticulatus. Identification of the disease agent has been based merely on size and morphology of the intraerythrocytic parasites and no evidence has been found concerning the subspecies (genotype) of B. canis. Therefore, a molecular survey on natural Babesia infection of dogs in Hungary using PCR and sequence analysis was attempted to clarify the subspecies (genotype) and to obtain information on the occurrence of B. canis. A total of 44 blood samples from dogs showing clinical signs of babesiosis were collected. A piroplasm-specific PCR amplifying the partial 18S rRNA gene yielded an approximately 450 bp PCR product in 39 (88.6%) samples. Thirteen positive samples originated from Budapest and 26 from 21 other locations. Five PCR products were chosen randomly for sequencing. The partial 18S rDNA sequences were submitted to GenBank (accession numbers AY611729; AY611730; AY611731; AY611732 and AY611733). The sequences showed 100% homology to one another or differed by one nucleotide. BLAST search against GenBank revealed the highest similarity (99.8 or 100%) with Babesia canis canis. The implication of these data, for the further study and diagnosis of canine babesiosis is discussed.

Epidemiological Survey of Babesia gibsoni Infection in Dogs in Eastern Japan

To determine the distribution of Babesia gibsoni infection in dogs in the eastern part of Japan, an epidemiological survey of dogs suspected of having B. gibsoni infection was attempted using the polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Thirty-five of 115 such dogs (30.4%) were positive by PCR and/or ELISA. The 35 positive dogs consisted of 28 Tosa dogs, 4 American Pit Bull Terriers, and 3 mongrel dogs in Aomori, Fukushima, Ibaraki, Gunma, Chiba, Tokyo, Kanagawa, and Nagano Prefectures. The positive dogs had a significantly lower rate of tick exposure and a higher rate of bites by other dogs. Twenty-two of 35 B. gibsoni-positive dogs were infected with hemoplasma, and the rate of infection was significantly higher than that of B. gibsoni-negative dogs.

Epidemiological study of equine piroplasmosis in Mongolia

The purpose of this study was to demonstrate the occurrence of equine piroplasmosis in Mongolia, a country in which the disease occurs epidemically in different climatic conditions. Antibodies to Babesia equi and B. caballi were determined in serum samples of 254 pastured horses in different locations of Mongolia using an enzyme-linked immunosorbent assay with recombinant antigens. One hundred and eighty-five (72.8%) and 102 (40.1%) of all serum samples were positive for B. equi and B. caballi infections, respectively. In addition, 78 (30.7%) samples were positive for both B. equi and B. caballi infections. These results indicate that equine piroplasmosis is widespread in Mongolia. To our knowledge, this is the first report describing an epidemiological study on equine piroplasmosis in different geographic regions in Mongolia.

First molecular detection of Babesia vogeli in dogs from Brazil

The present work describes the detection and first molecular characterization of Babesia vogeli in dogs, naturally infected in Brazil and even in South America. Microscopic examination of Giemsa-stained peripheral blood smears collected from dogs originating from four different locations in Brazil revealed the presence of large Babesia merozoites and trophozoites (>2.5 microm). DNA was extracted from infected blood samples and PCR amplifications of the 18S rDNA were carried out. As a reference, DNA from an isolate of B. vogeli originated from Egypt was used. PCR products were purified and sequenced. The DNA sequences demonstrated 100% identity among the Brazilian isolates. Comparisons with the 18S rDNA sequence of the B. vogeli isolate from Egypt and with other B. vogeli sequences from Spain, France, Japan, Australia and South Africa confirmed the affiliation of all Brazilian isolates to the species B. vogeli.

Immune response to Babesia bigemina infection in pregnant cows

Babesiosis is a tick-borne disease of cattle caused by Babesia bigemina and Babesia bovis and is transmitted by the tick vector Boophilus microplus. In this study, we investigate B. bigemina infection regarding the clinical infection, T cell distribution, and cytokine profile during the acute phase of an experimental infection in pregnant cows.

Identification, genetic diversity and prevalence of Theileria and Babesia species in a sheep population from Northern Spain

The genetic diversity and prevalence of virtually all Theileria and Babesia species in a sheep population were studied using a specifically designed reverse line blot macroarray. The amplified hypervariable V4 region of the 18S rRNA gene was hybridised against generic and species-specific probes. In a first screening (Study I), 320 apparently healthy animals corresponding to 32 flocks located in the Basque Country (Northern Spain) were analysed. The survey demonstrated a high prevalence of subclinical infections (64.7%). Three Theileria genotypes were identified, sharing 96.7-97.0% similarity between their 18S rRNA gene sequences: Theileria ovis, Theileria sp. OT1 (99.6% similarity with the recently described pathogenic piroplasm Theileria sp. China 1), and Theileria sp. OT3. Two Babesia species sharing 91.5% similarity were also detected: Babesia ovis and Babesia motasi. The complete 18S rRNA gene sequences of these and other piroplasm species were phylogenetically analysed. Prevalence of piroplasms was also investigated in a second group of 80 sheep from 16 flocks reared in mountain areas that had been heavily exposed to ticks and had suffered a recent abortion episode (Study II). The screening revealed a significantly higher (P < 0.05) prevalence (78.7%) of piroplasm infections compared to Study I. Although the prevalence rates for some piroplasm species were significantly related to abortion (e.g. Theileria sp. OT3), decreases in the red cell parameters were not significant. The widespread distribution of Theileria spp. in the studied sheep population suggests that the parasites involved are of relatively low pathogenicity, in contrast to what has been reported for Theileria sp. China 1 in other countries.

Epidemiological study of the prevalence of Babesia divergens in a veterinary practice in the mid-east of France

To assess the epidemiology of Babesia divergens in a veterinary practice based in the mid-east of France ("Monts du Lyonnais"), blood was collected from 254 cattle belonging to 24 herds. To assess the dynamics of the carrier state, six carriers were identified, treated with flumethrin and sampled once every 3 weeks during 6 months. Two different DNA extraction methods were compared. Each sample was tested for the presence of parasites using a PCR-RFLP test based on the 18S rRNA gene. The sensitivity of the test was equivalent to a parasitaemia as low as 10(-5)% (in "Filter Paper" samples) and 10(-6)% in 1 ml blood (extracted using "Matrix"). With the latter method, the rate of detection diminishes in the low parasitaemia range but could probably be improved. This test proved to be very useful in the detection of B. divergens carriers. Serology using IFAT showed 7% of the cattle seropositive, which is suggestive of a disease situation with a low clinical risk level. Analysis of the PCR results suggests a 20% prevalence rate of carriers in the cattle population. The use of the mean parasitaemia is proposed to serve as a babesiosis clinical risk indicator. This approach could also be used in other babesia infections provided the lowest detectable parasitaemia level (threshold level) could be resolved for each parasite species.

Molecular fluorescent approach to assessing intraerythrocytic hemoprotozoan Babesia canis infection in dogs

The development of recent flow cytometry-based protocols for the diagnosis of canine babesiosis, Babesia gibsoni in particular, has encouraged us to investigate its applicability to detect B. canis-infected erythrocytes as well as optimize the hydroethidine-flow cytometry methodology (HE-FC), using peripheral blood samples from naturally and experimentally infected dogs. Our data demonstrated that HE at 25 microg/ml provided the most outstanding fluorescence profile, able to discriminate between infected and uninfected dogs with no alterations in cell properties such as forward scatter and unspecific fluorescence. The results were expressed as the percentage of positive fluorescent erythrocytes (PPFE) for each individual sample, with 1.53% of PPFE as the cut-off determined between infected and uninfected animals. B. canis-infected erythrocytes during both acute and chronic experimental infection were identified through HE-FC, validating its use for diagnosis purposes in endemic areas for canine babesiosis. In a clinical trial, 22.8% out of 162 dogs showed to be positive to Babesia infection through this approach. Such prevalence was similar to that estimated for altered hematological profiles (HT) < or = 30% (29%), but highly distinct from the prevalence provided by direct blood smear (BS) examination (1.8%) or immunofluorescent assay (IFA) (60.5%). Furthermore, our findings indicate that positive PPFE data was associated with HT < or = 30%, emphasizing that, in clinical practice, the haematocrit should be used as a screening test followed by HE-FC, suitable to confirm hypotheses of canine babesiosis.

[Ehrlichia and Babesia infections in dogs in The Netherlands]

A retrospective study was performed at the Department of Clinical Sciences of Companion Animals at Utrecht University amongst 75 dogs diagnosed with a Babesia canis and/or an Ehrlichia canis infection. The majority of the dogs had visited an endemic area (most often the Mediterranean area or the Dutch Antilles), but two dogs became infected with Babesia in the Netherlands. Babesia infections were associated with a stay in an endemic area and an incubation period that are both significantly shorter (less than 3 months) than those for Ehrlichia and co-infections (more than 3 months). Reasons for the owner to seek veterinary attention (lethargy, anorexia, fever), findings from the physical examination (pale mucous membranes, hepato-/splenomegaly) and laboratory results (anemia, thrombocytopenia, hypo-albuminemia) were highly aspecific, making serology or PCR mandatory for diagnosing infections. Antigenic stimulation by the parasite sometimes resulted in immune-mediated diseases such as immune-mediated hemolytic anemia, thrombocytopenia, glomerulonefritis, and polyarthritis and in the case of ehrlichiosis in hypergammaglobulinemia. Specific therapy (imidocarb-diproprionate and/or doxycycline) was necessary, and because combined infections were common, it was considered appropriate to administer both drugs while the definitive diagnosis was being established. The prognosis was reasonably good, with almost half of all patients showing no clinical signs after treatment, although Babesia and co-infections were associated with a significantly longer survival sometimes resulted than Ehrlichia infections.