A survey of feline babesiosis in South Africa

South Africa appears to be the only country where feline babesiosis is a significant clinical entity in domestic cats. Little is known about its epidemiology or the clinical challenges facing practitioners. A questionnaire posted to 1760 South African veterinarians was returned by 16%, representing approximately 40% of practices. Just over half reported seeing feline babesiosis, with most cases occurring in the coastal areas of the Western Cape, Eastern Cape and KwaZulu-Natal Provinces. Overall incidence is highest in summer, but seasonality is less pronounced in non-seasonal and winter rainfall areas. No age, breed or sex predisposition was identified. Weight loss, weakness, anaemia, fever and icterus are common clinical findings. Complications include hepatopathy, renal failure, pulmonary oedema, cerebral signs, immune-mediated haemolytic anaemia and concurrent infections. The antibabesial drug of choice is primaquine phosphate. Response to therapy is generally good, but recurrence and chronic infections were identified as problems. The average mortality rate was 15%. Approximately 3000 cases are seen annually by the respondents, at an estimated cost of R750 000 to the owners. Feline babesiosis is a significant problem in South Africa, and further investigations of taxonomic status, concurrent infections, chemotherapy, complications and management of refractory cases are warranted.     

The effects of diminazene aceturate on systemic blood pressure in clinically healthy adult dogs

Diminazene aceturate is a commonly used antibabesial agent. It has been postulated that diminazine may induce a decrease in blood pressure and exacerbate the hypotension presented in dogs with babesiosis. This study was undertaken to assess the effect of diminazine aceturate on the blood pressure of healthy dogs. Six healthy German shepherd dogs between 18 and 24 months of age with a mean weight of 30.4 +/- 2.75 kg were used. Blood pressure was directly measured at the following time intervals: -5, 0, 5, 10, 15, 20, 25, 30, 35, 40, 50, 60, 90 and 120 minutes after treatment with diminazine aceturate (4.2 mg/kg) intramuscularly. No statistical difference (P > 0.05) was found in blood pressure between any of the time intervals. An increase in heart rate was seen 5 minutes after the administration of diminazine aceturate but no change in blood pressure was evident. This study concluded that diminazene aceturate in its current formulation with antipyrine does not alter blood pressure in healthy adult dogs.     

Clinicopathological changes and effect of imidocarb therapy in dogs experimentally infected with Babesia canis

In this study one spleen-intact dog (A) and two splenectomised dogs (BSE, CSE) were infected with Babesia canis. All animals developed an acute disease characterised by fever, haemoglobinuria and anaemia, the latter being more severe in the splenectomised dogs. Fever and parasitised red blood cells were detected for three days after imidocarb treatment in the splenectomised animals. Haematological abnormalities included regenerative anaemia, thrombocytopenia and leukopenia (due to neutropenia and lymphopenia) in the acute phase, soon followed by leukocytosis, neutrophilia and left shift a few days later. Acute hepatopathy was detected in all dogs with elevated ALT activity, which was more seriously altered in the splenectomised dogs. Diffuse changes in liver structure and hepatomegaly were seen by ultrasonography. Liver biopsy and histology revealed acute, non-purulent hepatitis in the splenectomised dogs. Both splenectomised dogs were successfully cured after collection of 400 ml highly parasitised blood, proving that large-amount antigen production is possible with rescuing the experimental animals. Whole blood transfusion, imidocarb and supportive care with infusions, antipyretics, glucocorticoids and diuretics were applied. The spleen-intact dog clinically recovered after receiving supportive treatment, with no imidocarb therapy. Microbial infections developed in both splenectomised animals (BSE: haemobartonellosis, CSE: osteomyelitis caused by Escherichia coli), probably as a consequence of immunosuppression after splenectomy and glucocorticoid therapy.     

Ixodid ticks on domestic dogs in the Northern Cape Province of South Africa and in Namibia

The objective of this study was to determine the species composition of ixodid ticks infesting domestic dogs in the northwestern region of the Northern Cape Province of South Africa and in Namibia. Ticks were collected from February 2008 to January 2009 from dogs presented for a variety of reasons at a veterinary clinic in the Northern Cape Province and at 3 clinics in Namibia. The ticks collected at each place were pooled separately for each month at each locality. Eleven ixodid tick species were collected from dogs in the Northern Cape Province and new locality records for Haemaphysalis colesbergensis and Ixodes rubicundus, new locality and host records for Hyalomma glabrum, and a new host record for Rhipicephalus neumanni are reported. Six tick species were collected from dogs at the 3 clinics in Namibia. The most numerous species on dogs in both countries was R. sanguineus. The present results increase the total number of ixodid tick species collected from dogs in South Africa from 25 to 28.     

Confirmation of occurrence of Babesia canis vogeli in domestic dogs in South Africa

The prevalence of Babesia infections in domestic dogs in South Africa was studied using reverse line blot hybridization and 18S sequence analysis. Babesia canis vogeli was confirmed for the first time in domestic dogs in South Africa. Out of a total of 297 blood samples collected from domestic dogs in Bloemfontein, East London, Johannesburg, Durban and from the Onderstepoort Veterinary Academic Hospital, 31 were positive for Babesia canis rossi, whereas B. c. vogeli was detected in 13 dogs. None of the dogs carried both parasites. The detection of B. c. vogeli has implications with regard to prevalence and varied clinical manifestation of canine babesiosis in South Africa.     

Evidence of an acute phase response in dogs naturally infected with Babesia canis

The erythrocyte sedimentation rate (ESR), white blood cell count (WBC), haematocrit (HCT) and platelet number (PLT) were quantified and compared with the acute phase proteins (APPs) in dogs naturally infected with Babesia canis and healthy dogs. Both groups were treated with imidocarb dipropionate on the day of admission and both groups were monitored for all parameters on the admission day and on the first, second, third, fourth and seventh days in order to determine the presence of an acute phase reaction, to assess the diagnostic value of these markers in uncomplicated canine babesiosis and to evaluate the use of APPs in treatment monitoring. It was demonstrated that an acute phase response occurs in dogs naturally infected with Babesia canis, with significant increases in the concentration of major acute phase proteins. The serum concentration of C-reactive protein (CRP), serum amyloid A (SAA) and the erythrocyte sedimentation rate (ESR) decreased daily after treatment and approached reference range values by the eighth day. PLT and haematocrit (HCT) increased daily after treatment and approached reference range values by the fourth day. WBC and haptoglobin increased after treatment and then decreased from the third and fourth days, respectively, to the eighth day. The diagnostic sensitivity of CRP, SAA and PLT was significantly higher compared to haptoglobin, ESR, HCT and the WBC count. CRP and SAA were of clinical use in monitoring the response to antibabesial treatment.     

Imidocarb: A chemoprophylactic experiment with Babesia canis

Summary

Eight dogs, given imidocarb dipropionate subcutaneously at a dose of 6 mg/kg, were challenged with a sporozoite stabilate of a French strain of Babesia canis, prepared from infected Dermacentor reticulatus ticks, 2, 3, 4 or 5 weeks after treatment. Three control dogs were similarly infected but not preventively treated. One of the controls and one of the dogs treated 5 weeks prior to challenge died of babesiosis. Prepatent and incubation periods were similar in treated and control dogs, and all dogs showed important reductions in the packed cell volume. Relaps'es were commonly seen after recovery from the initial reaction. Although further work is needed before a final conclusion can be drawn to whether imidocarb is suitable as a chemoprophylactic against B. canis infection, it can be used as a curative drug.     

Clinical and pathological findings of Babesia infection in dogs

The clinical and pathological findings of Babesia infection in 32 dogs in northern Australia are presented. Eleven different breed types were represented from 6 localities in north Queensland and one locality in northern Western Australia. Twenty three (72%) were males. Babesia-infected dogs were grouped by the degree of haematological disturbance and clinical severity: Acute babesiosis (25/32), all pups with severe haemolytic anaemia; subclinical carriers (5/32) with non-specific malaise, characterised haematologically by a normal erythrogram but marked leucopenia; chronic anaemia, observed in 2 adult dogs. Pups were azotaemic (serum urea greater than 6.6 mmol/l) and had elevated serum bilirubin levels (20.8 to 48.5 mmol/l). Total serum protein was usually within the normal range. Pups that died were also hypoglycaemic and severely hyperkalaemic (K+ greater than 10 mmol/l). Low parasitaemias in routine blood smears complicated diagnosis but smears made from ear or toe capillaries, or after haematocrit concentration, greatly enhanced finding parasitised cells. At necropsy, pallor and jaundice were the most consistent observations. Haemoglobinuric nephrosis, an active reticulo-endothelial system and capillaries packed with large numbers of infected erythrocytes were the main histopathological findings. A combination of imidocarb dipropionate at 5 mg/kg body weight, given intramuscularly, with fluid therapy and blood transfusion was the most successful treatment.     

Canine granulocytic ehrlichiosis (CGE) in Italy

Medical records of thirty-five consecutive cases of canine granulocytic ehrlichiosis (CGE) diagnosed cytologically in Central Italy in 1995-2000 were analysed retrospectively. Tick exposure was reported in 16 dogs (45.7%) and concurrent babesiosis in 19 dogs (54.3%). Ehrlichia-like inclusion bodies were found in neutrophils in a percentage varying from 0.5% to 11%. Frequently recorded clinical signs included anorexia (71.4%), lethargy (45.7%), conjunctivitis (31.4%), fever (25.7%), lameness (20%) and ataxia (20%). Among the 16 representative dogs in which protein, electrophoresis was performed, 10 (62.5%) showed high globulin levels and 6 (37.5%) had concurrent high total protein levels. During treatment with doxycycline, all associated symptoms, including those unusually described, such as pyoderma intertrigo, erythema, apparent blindness and oral papillomatosis, progressively disappeared in 31 (89%) out of 35 dogs. The efficacy of treatment was marked in dogs simultaneously treated twice with imidocarb dipropionate: among the 14 dogs in which a fast recovery was noted, 11 (80%) were concurrently affected by babesiosis and consequently treated with the specific medicament leading to excellent outcomes. The main conclusion is that CGE is present among dogs from Central Italy and should be included in the differential diagnosis of possible zoonotic agents affecting the canine population.     

Species composition and geographic distribution of ticks infesting cattle, goats and dogs in a temperate and in a subtropical region of south-east Africa

The species and distribution of ticks infesting cattle, goats and dogs in the eastern region of the Eastern Cape Province, South Africa and Maputo Province, Mozambique were determined from collections made from these animals at 72 localities in the former region and 30 in the latter. Eleven ixodid and one argasid species were recovered in the Eastern Cape Province and 15 ixodid species in Maputo Province. The most common ticks infesting cattle and goats in both provinces were Amblyomma hebraeum, Rhipicephalus (Boophilus) microplus, Rhipicephalus appendiculatus and Rhipicephalus evertsi evertsi. The dominant species on dogs were Haemaphysalis elliptica and Rhipicephalus simus. The geographic distributions of the major species and some of the minor species in both regions were plotted. The partial or complete displacement of the indigenous tick Rhipicephalus (Boophilus) decoloratus by the introduced species R. (B.) microplus was a major feature of both surveys.     

A survey of cattle tick control practices in the eastern Cape Province of South Africa.

Current cattle tick control practices and producer attitudes towards tick control in the eastern Cape Province of South Africa are discussed. These were ascertained from answers to a questionnaire survey to which 31.2% of farmers responded. In general, producers favoured intensive tick control. Beef and dairy farmers had a definite preference for synthetic pyrethroid acaricides, the majority followed a 25 times p.a. treatment frequency and most changed acaricides because of price. Beef producers favoured pour-on application of acaricides while the majority of dairy producers utilized plunge dipping. Producers who used hand spray techniques experienced the highest percentage of confirmed acaricide resistance. A costs of R11.27 for acaricide treatment per bovine per annum was calculated from data gained in this survey. A cost index of 2,496 was calculated by relating acaricide cost to the prevailing price of beef in the region. Only a small number of producers used heartwater, babesiosis and anaplasmosis vaccines. Relative tick borne disease mortality ratios indicated higher heartwater mortalities at high acaricide treatment frequencies. These results are discussed in relation to the tick control regimes practised.     

Concurrent bartonellosis and babesiosis in a dog with persistent thrombocytopenia

A 12-year-old castrated male West Highland White Terrier was referred because of recurrent episodes of collapsing. The dog was mildly anemic and severely thrombocytopenic and had high serum alanine aminotransferase activity. Infection with Bartonella vinsonii (berkhoffii) was initially diagnosed on the basis of serologic testing. Despite treatment with a series of antimicrobials and prolonged use of immunosuppressive drugs, thrombocytopenia persisted. After 5 months of treatment, Babesia canis organisms were seen during examination of a direct blood smear. The dog was treated with imidocarb dipropionate for babesiosis, after which thrombocytopenia resolved, and administration of immunosuppressive drugs was discontinued. Retrospective review of blood smears failed to identify organisms; however, polymerase chain reaction (PCR) analysis of multiple stored blood samples obtained during the 5-month period of persistent thrombocytopenia identified DNA of B. canis vogeli. Babesiosis may cause persistent, unexplained thrombocytopenia in dogs that are not anemic. A PCR assay can facilitate a diagnosis of babesiosis when organisms are not evident or when serologic testing fails to detect Babesia-specific antibodies.     

Molecular characterisation of Babesia gibsoni infection from a pit-bull terrier pup recently imported into South Africa

Canine babesiosis caused by Babesia gibsoni was diagnosed in a 3-month-old Pit-bull pup during a routine clinical examination. Diagnosis was confirmed by way of smear examination, PCR, Reverse Line Blot (RLB) and sequence analysis which showed 100% homology with B. gibsoni (Japan AB118032) and Babesia sp. (Oklahoma) (AF205636). Haematology showed moderate anaemia and severe thrombocytopenia. Treatment was initiated with diminazene aceturate (Berenil RTU) followed by 2 doses of imidocarb diproprionate (Forray-65) 3 days and 14 days later, respectively. Babesia gibsoni DNA was still detectable 2 weeks post-treatment on the PCR/RLB test. A 10-day course of combination drug therapy using atovaquone and azithromycin was initiated. Blood samples taken on Day 1 and Day 40 after completion of treatment were negative for B. gibsoni DNA on PCR/RLB test. The implications of a possible introduction of B. gibsoni into South Africa are discussed.     

Comparative efficacy of diminazene diaceturate and imidocarb dipropionate against Babesia equi infection in donkeys

Diminazene diaceturate (Berenil, Hoechst) at 12 mg/kg intramuscularly (i/m) and repeated after 24 hours controlled the rising parasitaemia of Babesia equi infection in four out of five splenectomised donkeys. The drug was more effective in the early stages of the disease and had a prophylactic effect for at least 30–35 days.A new babesicide, imidocarb (Imizol, Burroughs Wellcome), was 100% effective in three splenectomised donkeys at 5 mg/kg, i/m and repeated after 48 hours. However, imidocarb at 5 or 2 mg/kg i/m with a single injection was only partially effective or ineffective.     

Nitric oxide metabolites in naturally occurring canine babesiosis.

Babesiosis, caused by the virulent haemoprotozoan parasite Babesia canis rossi, is an important disease of dogs in South Africa. The nitric oxide metabolites, nitrate and nitrite (collectively termed reactive nitrogen intermediates or RNIs) were measured in admission sera from dogs in a babesiosis-endemic area. Five groups were prospectively studied: mild uncomplicated (n=9), severe uncomplicated (severe anaemia) (n=10) and complicated babesiosis (n=11); and two groups of healthy aparasitaemic dogs: endemic controls from the study area (n=10) and experimental dogs kept in tick-free conditions (n=10). Four measures of RNI production were studied: (i) serum RNI; (ii) serum RNI/creatinine ratio; (iii) fractional clearance of RNI (FC(RNI)); (iv) fractional excretion of RNI (FE(RNI)). Marked elevations of serum RNI occurred in only two dogs, both in the severe uncomplicated group. The highest concentration (log value 5.29 micromol/l) was in a dog that died, but concentrations in the other four dogs that died were unremarkable (0, 0.34, 1.66 and 2.64 micromol/l). Age, appetite and free serum haemoglobin were significant covariates for measures of RNI production. There were no significant differences among the babesiosis groups for serum RNI. Adjustment for creatinine had minor effects on the results. All babesiosis groups had significantly higher serum RNI and RNI/creatinine than the tick-free control group, but did not differ from the endemic controls except for the severe uncomplicated group, which had higher RNI/creatinine. The complicated group had significantly lower FC(RNI) and FE(RNI) than all other groups, except for the tick-free control group, which had similar FE(RNI). The results indicate that, in an endemic area, measures of RNI production are unlikely to be useful indicators of severity or outcome in canine babesiosis.     

Metabolic and electrolyte disturbances in acute canine babesiosis.

Arterial blood pH, PCO2, bicarbonate, base excess/deficit, and lactate, as well as serum sodium, potassium, and chloride were measured in clinically normal dogs and in dogs with acute canine babesiosis. Metabolic acidosis developed in dogs with fatal as well as nonfatal Babesia canis infection. In the fatal group, the acidosis was uncompensated; among survivors, base deficit and blood lactate were significantly lower, and pH, PCO2, and bicarbonate values were significantly higher. Serum potassium values were significantly lower, and serum chloride values were significantly higher in dogs with acute babesiosis than in clinically normal dogs. The shock resulting from acute canine babesiosis is best viewed as anemic shock. Treatment should include an alkalizing agent, a blood transfusion, fluid therapy, and a babesicidal drug.     

Chemotherapy against babesiosis

Babesiosis is caused by a haemotropic protozoal parasite of the genus Babesia, member of the phylum Apicomplexa and transmitted by the bite of an infected tick. There are many Babesia species affecting livestock, dogs, horses and rodents which are of economic significance. Infections can occur without producing symptoms, but babesiosis may also be severe and sometimes fatal caused by the intraerythrocytic parasite development. The disease can cause fever, fatigue and haemolytic anemia lasting from several days to several months. There are a number of effective babesiacides, but imidocarb dipropionate (which consistently clears the parasitaemia; often the only available drug on the market) and diminazene aceturate are the most widely used. Some Babesia spp. can infect humans, particularly Babesia microti and Babesia divergens, and human babesiosis is a significant emerging tick-borne zoonotic disease. Clinical manifestations differ markedly between European and North American diseases. In clinical cases, a combination of clindamycin and quinine is administered as the standard treatment, but also administration of atovaquone-azithromycin is successful. Supportive therapy such as intravenous fluids and blood transfusions are employed when necessary. More specific fast-acting new treatments for babesiosis have now to be developed. This should be facilitated by the knowledge of the Babesia spp. genome and increased interest for this malaria-like parasite.     

Anaesthesia and analgesia for dogs and cats in South Africa undergoing sterilisation and with osteoarthritis--an update from 2000

A survey was conducted in 2000 into the use of analgesic drugs by veterinarians in South Africa. This survey was repeated in 2005 to establish whether the use of analgesic drugs has increased and which analgesic drugs are being used for acute pain and osteoarthritis. The number of sterilisations performed and the number of new cases of osteoarthritis in dogs and cats was estimated. It is estimated that approximately 260000 cats are operated on each year in South Africa and that 150000 cats are sterilised. Five hundred thousand dogs undergo surgery, of which 242000 are sterilised. It appears that the number of surgical procedures performed in South Africa has decreased. The estimated death rate following anaesthesia has remained unchanged at 1:1004. Overall, the use of analgesics by South African veterinarians has increased significantly. Fifty-six per cent of cats and 74% of dogs were given peri-operative analgesics but this increased to 94% and 84% after including pre-anaesthetic medications with analgesic properties. The use of opioids (morphine and buprenorphine) and propofol has increased significantly. Approximately 253000 dogs and 33000 cats with osteoarthritis are seen by veterinarians in South Africa annually. The recognition by veterinarians of osteoarthritis in cats appears to be poor and is in need of attention. Carprofen and glucosamine/chondroitin are the most commonly used agents for the treatment of osteoarthritis. Details of the drugs used by veterinarians are given. Knowledge of analgesic drugs has increased significantly over the last 5 years. Continuing education is thought to have played an important role in the changes reported in this study.     

Could treatment of pregnant mares prevent abortions due to equine piroplasmosis?

Treatment of pregnant mares to prevent abortions due to equine piroplasmosis is a novel idea practised empirically at some Thoroughbred studs in South Africa. This paper presents the results of an investigation to ascertain whether imidocarb dipropionate crosses the equine placenta. Three pregnant mares were injected intramuscularly with imidocarb and their foetuses were mechanically aborted at varying time intervals thereafter. Imidocarb was found in foetal blood at a level similar to that in the dam's blood, suggesting that imidocarb administered to the dam would be available for anti-parasitic activity in the foetal circulation. Uncertainty concerning the time of treatment to achieve the desired effect currently makes this a questionable exercise.     

Pharmacokinetics of imidocarb dipropionate in horses after intramuscular administration

The objective of this study was to determine the pharmacokinetic behaviour of imidocarb in horses following a single i.m. injection at the dose commonly administered to treat Babesia caballi infections or to prevent babesiosis. Eight horses were injected i.m. with a single dose of 2.4 mg imidocarb dipropionate/kg bwt and blood, faecal, urine and milk samples were collected. For imidocarb determination, a high-performance liquid chromatographic method (HPLC) was used after weak cation-exchange solid phase, or liquid-liquid, extraction procedures. Twelve hours after treatment, no detectable plasma concentrations were recorded in any of the treated animals. The distribution and elimination patterns of the drug suggested that it is quickly sequestrated in some storage tissues and remains in the body for a long time. Its prolonged presence in the body may confer a reservoir effect to imidocarb in some tissues, therefore making it undetectable in the plasma of animals but sufficient to produce its described therapeutic and prophylactic activities.