First report of canine African trypanosomosis in the UK

Investigation on Prevalence of Canine Trypanosomiasis in the Conservation Areas of Bwindi-Mgahinga and Queen Elizabeth in Western Uganda

Nowadays, despite the instauration of several control strategies, animal trypanosomiasis continues to be reported all over Uganda. Few canine African trypanosomiasis (CAT) studies have been carried out, yet dogs are known Trypanosoma reservoirs that share identical home ranges with livestock and serve as parasite link between livestock and humans. This study evaluates the prevalence of CAT in dogs in the Bwindi-Mgahinga and Queen Elizabeth conservation areas. This information will be useful to evaluate the possible role of dogs in the transmission cycle of Trypanosoma species in livestock and wild animals. Trypanosome tests using microhematocrit centrifugation/dark ground microscopy technique (MHCT) followed by conventional polymerase chain reaction (cPCR) were performed in blood samples collected from identified indigenous dogs ( $n=124$ ). Four (3.23%) out of 124 dogs were positive for CAT. One dog was positive with Trypanosoma congolense and three with T. vivax. There was no significant statistical difference in CAT prevalence rate in relation to dog’s age, sex, and site ( $P>0.05$ ). This study reports what we believe is the first time detection of T. congolense and T. vivax in the indigenous dogs found in the Bwindi-Mgahinga and Queen Elizabeth conservation areas in western Uganda. The noticed T. congolense and T. vivax could be responsible for both canine and animal trypanosomiasis and represent a serious threat to the livestock industry. Therefore, there is a need for continuous trypanosomiasis surveillance and integrated management in contiguity to wildlife reserves.

Diagnosis and successful treatment of an Austrian dog infected with Trypanosoma congolense forest type

Canine African Trypanosomosis (CAT) is a rarely described disease with frequently lethal outcome. A 5-year-old female mongrel dog weighing 22 kg was presented in Austria due to unilateral uveitis, pancytopenia, and anorexia 4 months after return from a trip through Western Africa. Trypanosoma spp. flagellates were detected in a blood smear and identified as Trypanosoma congolense forest type by PCR. Initial treatment with imidocarb and miltefosine led to clinical improvement but only isometamidium chloride hydrochloride applied intramuscularly led to complete eradication of the pathogen from the dog's blood 4 months later.

Trypanocidal activity of methanol extracts of the hemolymph of Sarcophaga argyrostoma larva against Trypanosoma evansi infected mice

BACKGROUND AND AIM

Many natural products worldwide are used for medicinal purposes. Various insect-isolated compounds were investigated in pursuit of new therapeutic agents. This study aimed to compare the effects of methanol extract of hemolymph of Sarcophaga argyrostoma larvae with diminazene aceturate on some hematological and biochemical indices of mice infected with Trypanosoma evansi.

MATERIALS AND METHODS

Sixteen albino mice were randomly divided into four groups, of four mice, which received different treatments: In Group 1 (G1), mice were infected intraperitoneally with 1×104 T. evansi and received no treatment (positive control), in Group 2 (G2), infected mice were treated with 0.5 mL/kg of diminazene aceturate, in Group 3 (G3), infected mice were treated with 0.5 mL/kg methanol extract of the hemolymph of S. argyrostoma larvae, and in Group 4 (G4), uninfected mice received 0.5 ml of distilled water (negative control). In G3, treatment was started 3 days before injecting the parasite, while for the other groups, a single dose of treatment was applied when the parasite appeared in the blood.

RESULTS

Mice from G3 showed low parasitemia of 29×104/mm3 4 days post-infection until the infection completely disappeared on the 5th day, which was earlier than for other groups. The results showed that the numbers of red blood corpuscles (red blood cells [RBCs]) and white blood cells (WBCs) per unit volume were significantly different (p<0.05) between the four groups. The highest RBC (9.09×103 cell/ mm3) and WBC (14.30×103 cell/ mm3) counts were recorded in G3, whereas the lowest values of 6.60 and 4.60×103cell/ mm3, respectively, were recorded for G2. In addition, there were significant differences (p<0.05) between the different groups for platelet counts per unit volume, with G3 having the most (943×103 cell/ mm3) and G2 having the least (357×103 cell/ mm3). There was a significant (p<0.05) difference in the indices of biochemical activities between the extract-treated infected groups and the standard drug-treated group.

CONCLUSION

This study suggests that the methanol extract of the hemolymph of S. argyrostoma larva exhibits trypanocidal activity, so it may be exploited as a suitable candidate for the development of trypanocidal drugs.

Parasites of veterinary importance from domestic animals in uMkhanyakude district of KwaZulu-Natal province

This study investigated the occurrence and phylogenetic relationship of protozoan parasites and Ehrlichia infecting domestic animals from three municipalities in uMkhanyakude district of KwaZulu-Natal province, South Africa. A total of 208 blood samples collected from clinically healthy cattle, sheep, goats and dogs from uMkhanyakude district were examined by polymerase chain reaction (PCR) assays, using either genus or species-specific primers to determine the occurrence and phylogenetic relationship of various protozoan parasites and Ehrlichia of veterinary importance. A total of 5/109 (4.6%) cattle were PCR-positive for the presence of Toxoplasma gondii, 33/109 (30.3%) for Babesia bovis, 24/109 (22.02%) for Babesia bigemina and 20/109 (18.3%) for Trypanosoma sp., while 3/10 (30%) of sheep were PCR-positive for Theileria ovis and none of the goats were positive for any of the detected pathogens. The co-infection of 4/109 (3.7%) B. bovis and B. bigemina was detected in cattle. Only Ehrlichia canis was detected in dogs with infection rate of 20/48 (41.7%). Sequences of PCR-positive isolates (B. bovis, B. bigemina, E. canis, T. ovis and T. gondii) showed that they were closely related to their relevant species from various countries. These findings have expanded our knowledge about the prevalence and phylogenetic similarity between protozoan parasites and Ehrlichia isolates of South African origin. To date, this is the first study in South Africa to detect T. gondii infections from cattle blood using PCR.

Refractory hypoglycaemia in a dog infected with Trypanosoma congolense

A 20 kg German shepherd dog was presented to a French veterinary teaching hospital for seizures and hyperthermia. The dog had returned 1 month previously from a six-month stay in Senegal and sub-Saharan Africa. Biochemistry and haematology showed severe hypoglycaemia (0.12 g/L), anaemia and thrombocytopenia. Despite administration of large amounts of glucose (30 mL of 30% glucose IV and 10 mL of 70% sucrose by gavage tube hourly), 26 consecutive blood glucose measurements were below 0.25 g/L (except one). Routine cytological examination of blood smears revealed numerous free extracytoplasmic protozoa consistent with Trypanosoma congolense. PCR confirmed a Trypanosoma congolense forest-type infection. Treatment consisted of six injections of pentamidine at 48-hour intervals. Trypanosomes had disappeared from the blood smears four days following the first injection. Clinical improvement was correlated with the normalization of laboratory values. The infection relapsed twice and the dog was treated again; clinical signs and parasites disappeared and the dog was considered cured; however, 6 years after this incident, serological examination by ELISA T. congolense was positive. The status of this dog (infected or non-infected) remains unclear. Hypoglycaemia was the most notable clinical feature in this case. It was spectacular in its severity and in its refractory nature; glucose administration seemed only to feed the trypanosomes, indicating that treatment of hypoglycaemia may in fact have been detrimental.

Determination of the prevalence of African trypanosome species in indigenous dogs of Mambwe district, eastern Zambia, by loop-mediated isothermal amplification

Background

Dogs have been implicated to serve as links for parasite exchange between livestock and humans and remain an important source of emerging and re-emerging diseases including trypanosome infections. Yet, canine African trypanosomosis (CAT), particularly in indigenous dogs (mongrel breed) remains under- reported in literature. This study evaluated the performance of loop-mediated isothermal amplification (LAMP) in detecting trypanosomes in blood from indigenous dogs of tsetse-infested Mambwe district in eastern Zambia.

Methods

A cross sectional survey of CAT was conducted within 5 chiefdoms (Msoro, Kakumbi, Munkanya, Nsefu, Malama) of Mambwe district, eastern Zambia, during October 2012. Blood samples from 237 indigenous hunting dogs were collected and screened by microscopy and LAMP.

Results

Of the 237 dogs screened for CAT, 14 tested positive by microscopy (5.9%; 95% CI: 2.9 – 8.9%), all of which also tested positive by LAMP. In addition, LAMP detected 6 additional CAT cases, bringing the total cases detected by LAMP to 20 (8.4%; 95% CI: 4.9 – 12.0%). Irrespective of the detection method used, CAT was only recorded from 3 chiefdoms (Munkanya, Nsefu, Malama) out of the 5. According to LAMP, these infections were caused by Trypanosoma congolense, Trypanosoma brucei brucei and the zoonotic Trypanosoma brucei rhodesiense. Although these CAT cases generally did not manifest clinical illness, an association was observed between infection with Trypanosoma brucei subspecies and occurrence of corneal opacity.

Conclusions

This communication reports for the first time the occurrence of CAT in indigenous Zambian dogs. Our study indicates that LAMP is a potential diagnostic tool for trypanosome detection in animals. LAMP was more sensitive than microscopy and was further capable of distinguishing the closely related T. b. brucei and T. b. rhodesiense. In view of the sporadic cases of re-emerging HAT being reported within the Luangwa valley, detection of the human serum resistant associated (SRA) gene in trypanosomes from mongrels is intriguing and indicative of the risk of contracting HAT by local communities and tourists in Mambwe district. Consequently, there is a need for continuous trypanosome surveillances in animals, humans and tsetse flies using sensitive and specific tests such as LAMP.

Haematological and biochemical changes in experimental Trypanosoma evansi infection in rabbits

New Zealand white rabbits (N = 4) were challenged with the local strain of Trypanosoma evansi. Each rabbit was infected with 5 × 10(5) trypanosomes subcutaneously. The infection was characterized by intermittent pyrexia, undulating parasitaemia, anorexia and emaciation. The infected rabbits were examined daily for development of clinical signs and infection status by wet blood-films made from the ear veins. Thick and thin blood smears were also examined daily until the end of the experiment for description of blood cells. Differential leukocyte count (DLC) was also done. The parasite was observed in the blood during the acute phase only. Leukocytosis in the acute phase followed by leukopenia during the chronic phase was recognized. Haematological studies revealed reduced TEC, Hb and PCV. The main changes in the erythrocytes were macrocytes, hypochromic cells, Howell-Jolly bodies, target cells, stomatocytes and burr cells. Serum chemistry revealed hypoproteinemia, hypocholesterolaemia, hypoglycemia, hyperbilirubinemia, elevated creatinine, BUN, increased AST and ALT.

Preliminary investigation of trypanosomosis in exotic dog breeds from Zambia's Luangwa and Zambezi valleys using LAMP

Abstract. Canine African trypanosomosis (CAT) is rarely reported in the literature. In this preliminary study, we evaluated the performance of loop-mediated isothermal amplification (LAMP) against microscopy to detect CAT in six exotic dog breeds naturally infected with trypanosomes from Zambia's South Luangwa National Park and Chiawa Game Management Area. To our knowledge, this is the first report of CAT in Zambia. The patients exhibited a variety of aspecific clinical signs. The LAMP did not only confirm all six parasitologically positive CAT cases detected passively between April 2010 and January 2012, but was also critical in trypanosome speciation. According to LAMP, the majority of the dogs had monolytic infections with either Trypanosoma congolense or Trypanosoma brucei rhodesiense. The LAMP is thus a potential simple and cost-effective tool for trypanosome diagnosis in endemic regions. The rare report of zoonotic trypanosomes in dogs in Zambia has public health implications and justifies further investigations of CAT.