Epidemiological study of canine trypanosomosis in an urban area of Ivory Coast

Tsetse fly ecology and risk of transmission of African trypanosomes related to a protected forest area at a military base in the city of Abidjan, Côte d'Ivoire

African trypanosomoses, whose pathogens are transmitted by tsetse flies, are a threat to animal and human health. Tsetse flies observed at the military base of the French Forces in Côte d'Ivoire (FFCI base) were probably involved in the infection and death of military working dogs. Entomological and parasitological surveys were carried out during the rainy and dry seasons using "Vavoua" traps to identify tsetse fly species, their distribution, favorable biotopes and food sources, as well as the trypanosomes they harbor. A total of 1185 Glossina palpalis palpalis tsetse flies were caught, corresponding to a high average apparent density of 2.26 tsetse/trap/day. The results showed a heterogeneous distribution of tsetse at the FFCI base, linked to more or less favorable biotopes. No significant variation in tsetse densities was observed according to the season. The overall trypanosomes infection rate according to microscopic observation was 13.5%. Polymerase chain reaction (PCR) analyses confirmed the presence of Trypanosoma vivax and T. congolense forest type, responsible for African animal trypanosomosis. Our findings suggest that there is a risk of introduction and transmission of T. brucei gambiense, responsible for human African trypanosomiasis, on the study site. This risk of transmission of African trypanosomes concerns not only the FFCI base, but also inhabited peripheral areas. Our study confirmed the need for vector control adapted to the eco-epidemiological context of the FFCI base.

An African Canine Trypanosomosis Case Import: Is There a Possibility of Creating a Secondary Focus of Trypanosoma congolense Infection in France?

African animal trypanosomosis are parasitic diseases caused by several protozoa of the genus Trypanosoma, transmitted by hematophagous insects, essentially tsetse flies, but also, less frequently by Tabanidae and Stomoxidae. They are geolocated in a part of the continent and affect livestock animals and carnivores; dogs are especially sensitive to them. They do not seem to present a zoonotic risk. Despite the chemical prevention with trypanocides for French military working dogs on mission in Côte d’Ivoire, a fatal case induced by Trypanosoma congolense in France after returning from Abidjan raises the question of an imported secondary focus. The clinical case was developed and the causative agent was confirmed by microscopy and PCR methods. The three necessary pillars to create a secondary potential focus are present: the parasite introduction in a new territory, the presence and the propagation vectors, and their proximity with sensitive species.

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.

Molecular and serological detection of animal and human vector-borne pathogens in the blood of dogs from Côte d'Ivoire

In Côte d'Ivoire, limited information are available on vector-borne pathogens, their prevalence and distribution. Here, we assess the occurrence and diversity of canine vector-borne diseases (CVBDs) in Abidjan and Yamoussoukro cities. Blood from a total of 123 dogs were tested for Leishmania infantum and Ehrlichia canis antibodies and screened for Leishmania and Trypanosoma spp., Piroplasmida, Filariidae and Anaplasmataceae by PCR and sequencing. Among dogs, 39 % were positive for at least one pathogen. Seroprevalences were: 15.4 % and 12.2 % for L. infantum and E. canis, respectively. DNA of L. infantum and T. congolense (4.1 %), Baabesia vogeli (1.6 %), Filariidae (Dirofilaria immitis, D. repens and Acanthocheilonema reconditum) (10.6 %) has been detected. Anaplasmataceae were detected in (17.1 %) and E. canis was the only identified specie. Co-infections were observed in 13.8 % of dogs: E. canis-L. infantum co-infection was the most prevalent (4.9 %). Age, breed and sex of dogs do not seem to influence infections. Village dogs were more susceptible to CVBDs than kennel dogs (PV = 0.0000008). This study reports for the first time the presence of L. infantum, B. vogeli, A. reconditum, D. immitis and D. repens in dogs from Côte d'Ivoire and determines the prevalence and diversity of CVBD pathogens. The results indicate that human and animal pathogens are abundant in Ivoirian dogs which requires attention of veterinarians, physicians and authorities against these diseases, especially against major zoonosis such as visceral leishmaniasis (L. infantum).

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.

A study on African animal trypanosomosis in four areas of Senegal

In Senegal, several areas provide great potential for agriculture and animal production, but African animal trypanosomosis (AAT) is one of the major constraints to the development of more effective livestock production systems. A study was conducted to assess the current situation of AAT in this country. Surveys were carried out between June 2011 and September 2012 in four different areas: Dakar, Sine Saloum, Kedougou region and Basse Casamance in several animal species: dogs (152), donkeys (23), horses (63), sheep (43), goats (52) and cattle (104), distributed in the four sites. Molecular tools (PCR) indicated 3.4% positive animals including dogs, donkeys, a goat and cattle. The savannah type of Trypanosoma congolense Broden, 1904 (53% of positive cases) and the forest type of T. congolense (subgenus Nannomonas Hoare, 1964) were predominant. Trypanosoma vivax Ziemann, 1905 (subgenus Duttonella Chalmers, 1918) was only present in one animal and no trypanosome of the subgenus Trypanozoon Lühe, 1906 was found. Half of the positive cases were detected in Sine Saloum, where T. congolense savannah-type was predominant, and the other half in Basse Casamance, where T. congolense forest-type was predominant; no cases were found in Dakar or in the Kedougou region. A high risk of infection in dogs with T. congolense savannah-type was shown in Sine Saloum, requiring prevention and control of dogs in this area. The involvement of tsetse flies in the transmission of T. congolense in Sine Saloum and Basse Casamance is discussed.

Standardising visual control devices for tsetse flies: Central and West African species Glossina palpalis palpalis

BACKGROUND

Glossina palpalis palpalis (G. p. palpalis) is one of the principal vectors of sleeping sickness and nagana in Africa with a geographical range stretching from Liberia in West Africa to Angola in Central Africa. It inhabits tropical rain forest but has also adapted to urban settlements. We set out to standardize a long-lasting, practical and cost-effective visually attractive device that would induce the strongest landing response by G. p. palpalis for future use as an insecticide-impregnated tool in area-wide population suppression of this fly across its range.

METHODOLOGY/PRINCIPAL FINDINGS

Trials were conducted in wet and dry seasons in the Ivory Coast, Cameroon, the Democratic Republic of Congo and Angola to measure the performance of traps (biconical, monoconical and pyramidal) and targets of different sizes and colours, with and without chemical baits, at different population densities and under different environmental conditions. Adhesive film was used as a practical enumerator at these remote locations to compare landing efficiencies of devices. Independent of season and country, both phthalogen blue-black and blue-black-blue 1 m(2) targets covered with adhesive film proved to be as good as traps in phthalogen blue or turquoise blue for capturing G. p. palpalis. Trap efficiency varied (8-51%). There was no difference between the performance of blue-black and blue-black-blue 1 m(2) targets. Baiting with chemicals augmented the overall performance of targets relative to traps. Landings on smaller phthalogen blue-black 0.25 m(2) square targets were not significantly different from either 1 m(2) blue-black-blue or blue-black square targets. Three times more flies were captured per unit area on the smaller device.

CONCLUSIONS/SIGNIFICANCE

Blue-black 0.25 m(2) cloth targets show promise as simple cost effective devices for management of G. p. palpalis as they can be used for both control when impregnated with insecticide and for population sampling when covered with adhesive film.

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.

Phenetic and genetic structure of tsetse fly populations (Glossina palpalis palpalis) in southern Ivory Coast

BACKGROUND

Sleeping sickness, transmitted by G. p. palpalis, is known to be present in the Ivory Coast. G. p. palpalis has recently been reported to occur in several places within the town of Abidjan, including: (i) the Banco forest, (ii) the Abobo Adjamé University campus and (iii) the zoological park. Could these three places be treated sequentially, as separate tsetse populations, or should they be taken as one area comprising a single, panmictic population?

METHODS

The amount of gene flow between these places provides strategic information for vector control. It was estimated by the use of both microsatellite DNA and morphometric markers. The idea was to assess the interest of the faster and much less expensive morphometric approach in providing relevant information about population structure. Thus, to detect possible lack of insect exchange between these neighbouring areas of Abidjan, we used both genetic (microsatellite DNA) and phenetic (geometric morphometrics) markers on the same specimens.Using these same markers, we also compared these samples with specimens from a more distant area of south Ivory Coast, the region of Aniassué (186 km north from Abidjan).

RESULTS

Neither genetic nor phenetic markers detected significant differentiation between the three Abidjan G. p. palpalis samples. Thus, the null hypothesis of a single panmictic population within the city of Abidjan could not be rejected, suggesting the control strategy should not consider them separately. The markers were also in agreement when comparing G. p. palpalis from Abidjan with those of Aniassué, showing significant divergence between the two sites.

CONCLUSIONS

Both markers suggested that a successful control of tsetse in Abidjan would require the three Abidjan sites to be considered together, either by deploying control measures simultaneously in all three sites, or by a continuous progression of interventions following for instance the "rolling carpet" principle. To compare the geometry of wing venation of tsetse flies is a cheap and fast technique. Agreement with the microsatellite approach highlights its potential for rapid assessment of population structure.