RESUMO
Tsetse flies (Diptera: Glossinidae) are the cyclical vectors of human and animal trypanosomes. This viviparous insect develops and produces a single larva at 10-day intervals deposited in specific sites. In some species aggregation of larvae has been shown and seems to be mediated by both physical factors and volatile semiochemicals of larval origin. In this context, this study aims to identify chemicals emitted during the pupariation process in Glossina palpalis gambiensis. Volatile Organic Compounds (VOCs) emitted by larvae were identified using static headspace solid-phase microextraction and gas-chromatography mass-spectrometry (GC-MS) analysis. Electrophysiology and behavioural assays were performed on gravid females to confirm VOCs behavioural activity and attractiveness. GC-MS results revealed ten chemicals emitted during the pupariation process of G. p. gambiensis larvae. Among these chemicals, gravid females were shown to detect nine of them during coupled gas chromatography - electroantennographic detection tests. Behavioural assays highlighted two compounds were as attractive as pupae and one compound and a blend of four compounds were more attractive than pupae. Although the larval origin of some of them needs to be confirmed as they may also likely produced by micro-organisms, these compounds induced significant behavioural responses in the laboratory. Further experiments have to explore the biological activity and competitiveness of these compounds in the field. This work opens interesting opportunities for behavioural manipulation and control of tsetse flies.
RESUMO
Puparia are commonly found in tsetse fly larviposition sites during studies on larval ecology. This chitinous shell is representative of past or ongoing exploitation of these sites by tsetse flies. The morphological characteristics of the puparium are not sufficiently distinctive to allow identification of the species. This study explores the applicability of biomolecular techniques on empty puparia for tsetse fly species identification. Five techniques were compared for DNA extraction from tsetse fly puparia, 1/Chelex® 100 Resin, 2/CTAB, 3/Livak's protocol, 4/DEB + proteinase K and 5/QIAamp® DNA Mini kit, using two homogenisation methods (manual and automated). Using a combination of two primer pairs, Chelex, CTAB, and DEB + K proved the most efficient on fresh puparia with 90, 85, and 70% samples identified, respectively. Shifting from fresh to one- to nine-month-old puparia, the Chelex method gave the best result allowing species identification on puparia up to seven months old. The subsequent testing of the Chelex extraction protocol identified 152 (60%) of 252 field-collected puparia samples at species level. The results show that reliable genetic identification of tsetse flies species can be performed from empty puparia, what can prove of great interest for future ecological studies on larviposition sites. The Chelex technique was the most efficient for DNA extraction, though the age-limit of the samples stood at seven months, beyond which DNA degradation probably compromises the genetic analysis.
Assuntos
Pupa , Moscas Tsé-Tsé , Moscas Tsé-Tsé/genética , Animais , Larva/genética , DNA/análise , DNA/isolamento & purificação , Reação em Cadeia da PolimeraseRESUMO
BACKGROUND: Tsetse flies are vectors of African trypanosomes, protozoan parasites that cause sleeping sickness (or human African trypanosomosis) in humans and nagana (or animal African trypanosomosis) in livestock. In addition to trypanosomes, four symbiotic bacteria Wigglesworthia glossinidia, Sodalis glossinidius, Wolbachia, Spiroplasma and one pathogen, the salivary gland hypertrophy virus (SGHV), have been reported in different tsetse species. We evaluated the prevalence and coinfection dynamics between Wolbachia, trypanosomes, and SGHV in four tsetse species (Glossina palpalis gambiensis, G. tachinoides, G. morsitans submorsitans, and G. medicorum) that were collected between 2008 and 2015 from 46 geographical locations in West Africa, i.e. Burkina Faso, Mali, Ghana, Guinea, and Senegal. RESULTS: The results indicated an overall low prevalence of SGHV and Wolbachia and a high prevalence of trypanosomes in the sampled wild tsetse populations. The prevalence of all three infections varied among tsetse species and sample origin. The highest trypanosome prevalence was found in Glossina tachinoides (61.1%) from Ghana and in Glossina palpalis gambiensis (43.7%) from Senegal. The trypanosome prevalence in the four species from Burkina Faso was lower, i.e. 39.6% in Glossina medicorum, 18.08%; in Glossina morsitans submorsitans, 16.8%; in Glossina tachinoides and 10.5% in Glossina palpalis gambiensis. The trypanosome prevalence in Glossina palpalis gambiensis was lowest in Mali (6.9%) and Guinea (2.2%). The prevalence of SGHV and Wolbachia was very low irrespective of location or tsetse species with an average of 1.7% for SGHV and 1.0% for Wolbachia. In some cases, mixed infections with different trypanosome species were detected. The highest prevalence of coinfection was Trypanosoma vivax and other Trypanosoma species (9.5%) followed by coinfection of T. congolense with other trypanosomes (7.5%). The prevalence of coinfection of T. vivax and T. congolense was (1.0%) and no mixed infection of trypanosomes, SGHV and Wolbachia was detected. CONCLUSION: The results indicated a high rate of trypanosome infection in tsetse wild populations in West African countries but lower infection rate of both Wolbachia and SGHV. Double or triple mixed trypanosome infections were found. In addition, mixed trypanosome and SGHV infections existed however no mixed infections of trypanosome and/or SGHV with Wolbachia were found.
Assuntos
Citomegalovirus/isolamento & purificação , Trypanosoma/isolamento & purificação , Moscas Tsé-Tsé/microbiologia , Moscas Tsé-Tsé/parasitologia , Moscas Tsé-Tsé/virologia , Wolbachia/isolamento & purificação , África Ocidental , Animais , Citomegalovirus/patogenicidade , Geografia , Gana , Humanos , Insetos Vetores/microbiologia , Insetos Vetores/parasitologia , Insetos Vetores/virologia , Prevalência , Spiroplasma/isolamento & purificação , SimbioseRESUMO
BACKGROUND: The measure of new drug- or vaccine-based approaches for malaria control is based on direct membrane feeding assays (DMFAs) where gametocyte-infected blood samples are offered to mosquitoes through an artificial feeder system. Gametocyte donors are identified by the microscopic detection and quantification of malaria blood stages on blood films prepared using either capillary or venous blood. However, parasites are known to sequester in the microvasculature and this phenomenon may alter accurate detection of parasites in blood films. The blood source may then impact the success of mosquito feeding experiments and investigations are needed for the implementation of DMFAs under natural conditions. METHODS: Thick blood smears were prepared from blood obtained from asymptomatic children attending primary schools in the vicinity of Mfou (Cameroon) over four transmission seasons. Parasite densities were determined microscopically from capillary and venous blood for 137 naturally-infected gametocyte carriers. The effect of the blood source on gametocyte and asexual stage densities was then assessed by fitting cumulative link mixed models (CLMM). DMFAs were performed to compare the infectiousness of gametocytes from the different blood sources to mosquitoes. RESULTS: Prevalence of Plasmodium falciparum asexual stages among asymptomatic children aged from 4 to 15 years was 51.8% (2116/4087). The overall prevalence of P. falciparum gametocyte carriage was 8.9% and varied from one school to another. No difference in the density of gametocyte and asexual stages was found between capillary and venous blood. Attempts to perform DMFAs with capillary blood failed. CONCLUSIONS: Plasmodium falciparum malaria parasite densities do not differ between capillary and venous blood in asymptomatic subjects for both gametocyte and trophozoite stages. This finding suggests that the blood source should not interfere with transmission efficiency in DMFAs.
Assuntos
Capilares/parasitologia , Malária Falciparum/epidemiologia , Parasitemia/epidemiologia , Plasmodium falciparum/isolamento & purificação , Veias/parasitologia , Adolescente , Camarões/epidemiologia , Criança , Pré-Escolar , Feminino , Humanos , Malária Falciparum/parasitologia , Masculino , Parasitemia/parasitologia , PrevalênciaRESUMO
Culicoides biting midges (Diptera: Ceratopogonidae) are important vectors of arboviruses in Africa. Culicoides oxystoma has been recently recorded in the Niayes region of Senegal (West Africa) and its high abundance on horses suggests a potential implication in the transmission of the African horse sickness virus in this region. This species is also suspected to transmit bluetongue virus to imported breeds of sheep. Little information is available on the biology and ecology of Culicoides in Africa. Therefore, understanding the circadian host-seeking activity of this putative vector is of primary importance to assess the risk of the transmission of Culicoides-borne pathogens. To achieve this objective, midges were collected using a sheep-baited trap over two consecutive 24-h periods during four seasons in 2012. A total of 441 Culicoides, belonging to nine species including 418 (94.8%) specimens of C. oxystoma, were collected. C. oxystoma presented a bimodal circadian host-seeking activity at sunrise and sunset in July and was active 3 h after sunrise in April. Daily activity appeared mainly related to time periods. Morning activity increased with the increasing temperature up to about 27 °C and then decreased with the decreasing humidity, suggesting thermal limits for C. oxystoma activity. Evening activity increased with the increasing humidity and the decreasing temperature, comprised between 20 and 27 °C according to seasons. Interestingly, males were more abundant in our sampling sessions, with similar activity periods than females, suggesting potential animal host implication in the facilitation of reproduction. Finally, the low number of C. oxystoma collected render practical vector-control recommendations difficult to provide and highlight the lack of knowledge on the bio-ecology of this species of veterinary interest.
Assuntos
Vírus da Doença Equina Africana/fisiologia , Vírus Bluetongue/fisiologia , Ceratopogonidae/fisiologia , Ritmo Circadiano/fisiologia , Insetos Vetores/fisiologia , Animais , Ceratopogonidae/virologia , Feminino , Umidade , Insetos Vetores/virologia , Masculino , Estações do Ano , SenegalRESUMO
Mosquitoes harbor a large diversity of eukaryotic viruses. Those viromes probably influence mosquito physiology and the transmission of human pathogens. Nevertheless, their ecology remains largely unstudied. Here, we address two key questions in virome ecology. First, we assessed the influence of mosquito species on virome taxonomic diversity and relative abundance. Contrary to most previous studies, the potential effect of the habitat was explicitly included. Thousands of individuals of Culex poicilipes and Culex tritaeniorhynchus, two vectors of viral diseases, were concomitantly sampled in three habitats over two years. A total of 95 viral taxa from 25 families were identified with meta-transcriptomics, with 75% of taxa shared by both mosquitoes. Viromes significantly differed by mosquito species but not by habitat. Differences were largely due to changes in relative abundance of shared taxa. Then, we studied the diversity of viruses with a broad host range. We searched for viral taxa shared by the two Culex species and Aedes vexans, another disease vector, present in one of the habitats. Twenty-six out of the 163 viral taxa were found in the three mosquitoes. These taxa encompassed 14 families. A database analysis supported broad host ranges for many of those viruses, as well as a widespread geographical distribution. Thus, the viromes of mosquitoes from the same genera mainly differed in the relative abundance of shared taxa, whereas differences in viral diversity dominated between mosquito genera. Whether this new model of virome diversity and structure applies to other mosquito communities remains to be determined.
Assuntos
Culex , Especificidade de Hospedeiro , Mosquitos Vetores , Viroma , Animais , Viroma/genética , Culex/virologia , Mosquitos Vetores/virologia , Aedes/virologia , Culicidae/virologia , Ecossistema , Simpatria , Vírus/classificação , Vírus/genética , Vírus/isolamento & purificaçãoRESUMO
African animal trypanosomosis (AAT) was one of the main disease-related constraints to the development of intensive livestock production systems in the Niayes region of Senegal, a 30 km wide strip of land along the coast between Dakar and Saint-Louis. To overcome this constraint, the Government of Senegal initiated an area-wide integrated pest management programme combining chemical control tactics with the sterile insect technique to eradicate a population of the tsetse fly Glossina palpalis gambiensis Vanderplank, 1949 (Diptera, Glossinidae) in this area. The project was implemented following a phased conditional approach, and the target area was divided into three blocks treated sequentially. This study aims to assess the temporal dynamics of the prevalence of Trypanosoma spp. during the implementation of this programme. Between 2009 and 2022, 4,359 blood samples were collected from cattle and screened for trypanosomes using both the buffy coat and ELISA techniques, and PCR tests since 2020. The seroprevalence decreased from 18.9% (95%CI: 11.2-26.5) in 2009 to 0% in 2017-2022 in block 1, and from 92.9% (95%CI: 88.2-97) in 2010 to 0% in 2021 in block 2. The parasitological and serological data confirm the entomological monitoring results, i.e., that there is a high probability that the population of G. p. gambiensis has been eradicated from the Niayes and that the transmission of AAT has been interrupted in the treated area. These results indicate the effectiveness of the adopted approach and show that AAT can be sustainably removed through the creation of a zone free of G. p. gambiensis.
Title: Trypanosomose animale éliminée dans une importante région de production d'élevage au Sénégal suite à l'éradication d'une population de glossines. Abstract: La trypanosomose animale africaine (TAA) était l'une des principales contraintes pathologiques au développement de systèmes de production animale intensifs dans les Niayes du Sénégal, une bande de terre large de 30 km longeant la côte entre Dakar et Saint-Louis. Pour surmonter cette contrainte, le Gouvernement du Sénégal a lancé un programme de lutte intégrée à l'échelle de la zone combinant lutte chimique et technique de l'insecte stérile pour éradiquer une population de Glossina palpalis gambiensis Vanderplank, 1949 (Diptera, Glossinidae). Le projet a été mis en Åuvre selon une approche conditionnelle progressive, et la zone cible a été divisée en trois blocs, traités de manière séquentielle. L'objectif de cette étude était d'évaluer la dynamique temporelle de la prévalence de Trypanosoma spp. au cours de la mise en Åuvre du programme. Entre 2009 et 2022, 4 359 échantillons de sang ont été prélevés sur des bovins et ont fait l'objet d'un dépistage des trypanosomes à l'aide des techniques du buffy-coat et ELISA, ainsi que de test PCR depuis 2020. Dans le bloc 1, la séroprévalence est passée de 18,9 % (IC 95 % : 11,226,5) en 2009 à 0 % entre 20172022 et de 92,9 % (IC 95 % : 88,2-97) en 2010 à 0 % en 2021 pour le block 2. Les données parasitologiques et sérologiques confirment les résultats du suivi entomologique selon lesquels il est très probable que la population de Glossina palpalis gambiensis soit éradiquée des Niayes, et que la transmission de la TAA a été interrompue dans la zone traitée. Elles indiquent l'efficacité de l'approche adoptée, et montrent que la TAA peut être durablement éliminée grâce à la création d'une zone exempte de G. p. gambiensis.
Assuntos
Doenças dos Bovinos , Tripanossomíase Africana , Tripanossomíase , Animais , Bovinos , Gado , Senegal/epidemiologia , Estudos Soroepidemiológicos , Tripanossomíase Africana/epidemiologia , Tripanossomíase Africana/prevenção & controle , Tripanossomíase Africana/veterináriaRESUMO
This study examines the occurrence of Surra, a disease caused by Trypanosoma evansi, in camels in the Canary Islands. The 1997 detection of T. evansi in camels in the Canary Islands led to the implementation of an initial control program, resulting in a decrease in prevalence. Following an outbreak in 2014, and due to the impossibility of eradicating it using the conventional measures, a lazaret was set up to separate positive and suspicious animals, in addition to the control measures previously implemented. Stomoxys calcitrans was the only vector captured, and no other animals tested were found to be positive for T. evansi. In November 2019, the last camels that tested serologically positive were detected; however, since February 2018, no camels that tested positive for PCR have been found in the farms were the outbreak was detected, suggesting that the sanitary measures implemented are adequate. The duration of the outbreak control and potential eradication for the disease has yet to be established. This study provides evidence to facilitate the control of African Animal Trypanosomosis in endemic areas of the world, which may contribute to revise the World Organization for Animal Health (WOAH) protocol to implement recommendations of surveillance and control strategies for animal Trypanosomosis in camels.
Assuntos
Trypanosoma , Tripanossomíase Africana , Tripanossomíase , Animais , Espanha/epidemiologia , Trypanosoma/genética , Tripanossomíase/epidemiologia , Tripanossomíase/prevenção & controle , Tripanossomíase/veterinária , Reação em Cadeia da Polimerase/veterinária , CamelusRESUMO
Animal African trypanosomosis is an important vector-borne disease of livestock in sub-Saharan Africa. Pigs seem relatively tolerant to trypanosome infection and could act as a reservoir of trypanosomes affecting animals and humans. Our ability to reliably detect trypanosome infection in pigs depends on the performance of diagnostic tools, which is not well known. In pigs experimentally infected with Trypanosoma brucei brucei, we evaluated the performance of parasitological Buffy Coat Technique (BCT), two molecular (TBR and 5.8S PCR) and four serological tests (CATT, HAT Sero-K-Set rapid diagnostic test-RDT, indirect ELISA, immune trypanolysis). Most diagnostic tests showed high specificity, estimated at 100% (95% CI = 74-100%) with the exception of CATT and RDT whose specificity varied between 100% (95% CI = 74-100%) to 50% (95% CI = 7-93%) during the experiment. The sensitivity of each test fluctuated over the course of the infection. The percentage of positive BCT over the infection (30%) was lower than of positive PCR (56% and 62%, depending on primers). Among the serological tests, the percentage of positive tests was 97%, 96%, 86% and 84% for RDT, ELISA, immune trypanolysis and CATT, respectively. Fair agreement was observed between both molecular tests (κ = 0.36). Among the serological tests, the agreement between the ELISA and the RDT was substantial (κ = 0.65). Our results on the T.b. brucei infection model suggest that serological techniques are efficient in detecting the chronic phase of infection, PCR is able to detect positive samples several months after parasites inoculation while BCT becomes negative. BCT examination and RDT are useful to get a quick information in the field, and BCT can be used for treatment decision. ELISA appears most suited for epidemiological studies. The selection of diagnostic tests for trypanosomosis in pigs depends on the context, the objectives and the available resources.
Assuntos
Trypanosoma brucei brucei , Trypanosoma , Tripanossomíase Africana , Humanos , Animais , Suínos , Tripanossomíase Africana/diagnóstico , Tripanossomíase Africana/veterinária , Tripanossomíase Africana/parasitologia , Gado , Testes Diagnósticos de Rotina , Sensibilidade e EspecificidadeRESUMO
African animal trypanosomoses are vector-borne diseases that cause enormous livestock losses in sub-Saharan Africa, with drastic socio-economic impacts. Vector control in the context of an area-wide integrated pest management program with a sterile insect technique component requires the production of high-quality sterile male tsetse flies. In our study, we evaluated the effect of irradiation on the fecundity of Glossina palpalis gambiensis to identify the optimal dose that will induce maximum sterility while maintaining biological performance as much as possible. In addition, male mating performance was evaluated in semi-field cages. The irradiation doses used were 90, 100, 110, 120, 130, 140, and 150 Gy, and untreated males were used as the control. The results showed that pupal production and emergence rates were higher in batches of females that had mated with fertile males than in those that had mated with irradiated males with any experimental dose. A dose of 120 Gy administered to male flies induced 97-99% sterility after mating with virgin females. For the semi-field cage experiments, males irradiated with 120 Gy showed good sexual competitiveness as compared to fertile males and those irradiated with 140 Gy, considering the level of filling of spermatheca and the number of pairs formed. The optimal radiation dose of 120 Gy found in this study is slightly different from the traditional dose of 110 Gy that has been used in several eradication programmes in the past. The potential reasons for this difference are discussed, and an argument is made for the inclusion of reliable dosimetry systems in these types of studies.
Title: Le rayonnement gamma pour Glossina palpalis gambiensis revisité : effet sur la fertilité et la compétitivité sexuelle. Abstract: Les trypanosomoses animales africaines sont des maladies à transmission vectorielle qui causent d'énormes pertes de bétail en Afrique subsaharienne, avec des impacts socio-économiques importants. La lutte antivectorielle dans le cadre d'un programme de lutte intégrée contre les ravageurs à l'échelle d'une zone avec une composante de technique d'insectes stériles nécessite la production de glossines mâles stériles de haute qualité. Dans notre étude, nous avons évalué l'effet de l'irradiation sur la fécondité de Glossina palpalis gambiensis afin d'identifier la dose optimale qui induira une stérilité maximale tout en maintenant au maximum les performances biologiques. De plus, les performances d'accouplement des mâles ont été évaluées en cages de semi-terrain. Les doses d'irradiation utilisées étaient de 90, 100, 110, 120, 130, 140 et 150 Gy, et des mâles non traités ont été utilisés comme contrôle. Les résultats ont montré que les taux de production et d'émergence de pupes étaient plus élevés dans les lots de femelles qui s'étaient accouplées avec des mâles fertiles que dans les lots de celles accouplées avec des mâles irradiés, avec n'importe quelle dose expérimentale. Une dose de 120 Gy administrée à des mouches mâles a induit une stérilité de 97 à 99 % après accouplement avec des femelles vierges. Pour les expériences en cages de semi-terrain, les mâles irradiés à 120 Gy ont montré une bonne compétitivité sexuelle par rapport aux mâles fertiles et à ceux irradiés à 140 Gy, en considérant le niveau de remplissage de leur spermathèque et le nombre de couples formés. La dose de rayonnement optimale de 120 Gy trouvée dans cette étude est légèrement différente de la dose traditionnelle de 110 Gy qui a été utilisée dans plusieurs programmes d'éradication dans le passé. Les raisons potentielles de cette différence sont discutées et un argument est avancé pour l'inclusion de systèmes de dosimétrie fiables dans ce type d'études.
Assuntos
Infertilidade , Tripanossomíase Africana , Moscas Tsé-Tsé , Animais , Feminino , Masculino , Comportamento Sexual Animal/efeitos da radiação , Reprodução , FertilidadeRESUMO
The biological quality of sterile male insects produced in a mass-rearing facility is a prerequisite for the success of the SIT, which is a component of area-wide integrated pest management (AW-IPM). Indeed, sterile male insects released in the field must have a good mating performance in order to compete with wild males, but they must also present the required level of sterility. In the present study, the biological quality of sterile male Glossina palpalis gambiensis produced in a mass-rearing insectary was assessed through quality control testing. The mating performance of irradiated males was assessed in walk-in field cages. Irradiation had no effect on adult emergence but significantly reduced the percentage of operational flies (from 89.58% to 79.87%) and male survival (from 5 to 4 days, on average). However, irradiation did not impact the sterile male insemination potential, with all females inseminated and more than 80% of the spermathecae completely filled. The rate of induced sterility in females was 89.67% due to a dose rate decrease of the radiation source. Moreover, sterile males were able to compete successfully with untreated fertile males for untreated females in walk-in field cages. This study confirmed that the flies were still competitive and stressed the importance of regularly checking the radiation source parameters.
RESUMO
BACKGROUND: Animal African Trypanosomosis (AAT) is a parasitic disease of livestock that has a major socio-economic impact in the affected areas. It is caused by several species of uniflagellate extracellular protists of the genus Trypanosoma mainly transmitted by tsetse flies: T. congolense, T. vivax and T. brucei brucei. In Burkina Faso, AAT hampers the proper economic development of the southwestern part of the country, which is yet the best watered area particularly conducive to agriculture and animal production. It was therefore important to investigate the extent of the infection in order to better control the disease. The objective of the present study was to assess the prevalence of trypanosome infections and collect data on the presence of tsetse flies. METHODS: Buffy coat, Trypanosoma species-specific PCR, Indirect ELISA Trypanosoma sp and trypanolysis techniques were used on 1898 samples collected. An entomological survey was also carried out. RESULTS: The parasitological prevalence of AAT was 1.1%, and all observed parasites were T. vivax. In contrast, the molecular prevalence was 23%, of which T. vivax was predominant (89%) followed by T. congolense (12.3%) and T. brucei s.l. (7.3%) with a sizable proportion as mixed infections (9.1%). T. brucei gambiense, responsible of sleeping sickness in humans, was not detected. The serological prevalence reached 49.7%. Once again T. vivax predominated (77.2%), but followed by T. brucei (14.7%) and T. congolense (8.1%). Seven samples, from six cattle and one pig, were found positive by trypanolysis. The density per trap of Glossina tachinoides and G. palpalis gambiensis was 1.2 flies. CONCLUSIONS/SIGNIFICANCE: Overall, our study showed a high prevalence of trypanosome infection in the area, pointing out an ongoing inadequacy of control measures.
Assuntos
Trypanosoma congolense , Trypanosoma , Tripanossomíase Africana , Moscas Tsé-Tsé , Animais , Burkina Faso/epidemiologia , Bovinos , Humanos , Insetos Vetores/parasitologia , Epidemiologia Molecular , Suínos , Trypanosoma/genética , Trypanosoma congolense/genética , Trypanosoma vivax/genética , Tripanossomíase Africana/epidemiologia , Tripanossomíase Africana/parasitologia , Tripanossomíase Africana/veterinária , Moscas Tsé-Tsé/parasitologiaRESUMO
In the context of the human African trypanosomiasis elimination process, reliable and accurate diagnostic tools are crucial for exploring the role of a potential animal reservoir of Trypanosoma brucei gambiense. The immune trypanolysis test (TL) using the variant antigen types (VAT) LiTat 1.3 and LiTat 1.5, described as a specific serological method to detect people infected by T. b. gambiense, seems to be a promising tool. However, its specificity was recently questioned during field animal surveys. The present study evaluates the performance of TL during experimental T. b. brucei infection in pigs. Eight infected pigs and four uninfected pigs were followed up with blood and plasma collection. Blood was used for parasitological investigation. TL was performed on the plasma with the LiTat 1.3, LiTat 1.5 and LiTat 1.6 VATs. All control pigs remained negative to parasitological investigation and TL. Trypanosomes were detected in all the infected pigs and the first detection was between 10 and 14 days post infection (dpi). TL results showed that infected pigs developed antibodies against the three VATs. The first antibody detections by TL occurred between 14 and 21 dpi for antibodies directed against LiTat 1.6, 21 and 168 dpi for antibodies directed against LiTat 1.5 and 70, and 182 dpi for antibodies directed against LiTat 1.3. This study highlights for the first time that TL using LiTat 1.3 and LiTat 1.5 VATs is not specific to T. b. gambiense. Development of specific diagnostic tools for the detection of T. b. gambiense infections in animals, especially in pigs, is still needed.
Title: Évidence expérimentale que la trypanolyse basée sur les types d'antigène variable LiTat 1.3 et LiTat 1.5 n'est pas spécifique de Trypanosoma brucei gambiense. Abstract: Dans le contexte d'élimination de la trypanosomiase humaine Africaine, des outils de diagnostic fiables et précis sont essentiels afin d'explorer le rôle d'un potentiel réservoir animal de Trypanosoma brucei gambiense. La trypanolyse (TL) qui utilise les types d'antigène variable (TAV) LiTat 1.3 et LiTat 1.5, et qui est décrite comme une méthode sérologique spécifique pour détecter les personnes infectées par T. b. gambiense, semble être un outil prometteur. Cependant, sa spécificité a été récemment remise en question lors d'enquêtes sur les animaux. La présente étude évalue la performance de ce test lors d'une infection expérimentale à T. b. brucei chez le porc. Huit porcs infectés et quatre porcs témoins non infectés ont été suivis avec des prélèvements de sang et de plasma. Le sang a été utilisé pour l'examen parasitologique. La TL a été réalisée sur les échantillons de plasma avec les TAV LiTat 1.3, LiTat 1.5 et LiTat 1.6. Tous les porcs témoins ont été négatifs en parasitologie et à la TL. Les trypanosomes ont été détectés sur tous les porcs infectés avec les premières détections entre 10 et 14 jours post-infection (jpi). Les résultats de la TL ont montré que les porcs infectés ont développé des anticorps contre les trois TAV. Les premiers anticorps détectés par la TL étaient dirigés contre le LiTat 1.6 entre 14 et 21 jpi, puis le LiTat 1.5 entre 21 et 168 jpi et enfin le LiTat 1.3 entre 70 et 182 jpi. Cette étude démontre pour la première fois que la TL basée sur les TAV LiTat 1.3 et LiTat 1.5 n'est pas spécifique de T. b. gambiense. Il est donc toujours nécessaire et urgent de développer un outil de diagnostic spécifique pour la détection des infections à T. b. gambiense chez les animaux, notamment chez les porcs.
Assuntos
Trypanosoma brucei gambiense , Tripanossomíase Africana , Animais , Humanos , Suínos , Tripanossomíase Africana/diagnóstico , Tripanossomíase Africana/veterinária , Anticorpos AntiprotozoáriosRESUMO
Reliable diagnostic tools are needed to choose the appropriate treatment and proper control measures for animal trypanosomoses, some of which are pathogenic. Trypanosoma cruzi, for example, is responsible for Chagas disease in Latin America. Similarly, pathogenic animal trypanosomoses of African origin (ATAO), including a variety of Trypanosoma species and subspecies, are currently found in Africa, Latin America and Asia. ATAO limit global livestock productivity and impact food security and the welfare of domestic animals. This review focusses on implementing previously reviewed diagnostic methods, in a complex epizootiological scenario, by critically assessing diagnostic results at the individual or herd level. In most cases, a single diagnostic method applied at a given time does not unequivocally identify the various parasitological and disease statuses of a host. These include "non-infected", "asymptomatic carrier", "sick infected", "cured/not cured" and/or "multi-infected". The diversity of hosts affected by these animal trypanosomoses and their vectors (or other routes of transmission) is such that integrative, diachronic approaches are needed that combine: (i) parasite detection, (ii) DNA, RNA or antigen detection and (iii) antibody detection, along with epizootiological information. The specificity of antibody detection tests is restricted to the genus or subgenus due to cross-reactivity with other Trypanosoma spp. and Trypanosomatidae, but sensitivity is high. The DNA-based methods implemented over the last three decades have yielded higher specificity and sensitivity for active infection detection in hosts and vectors. However, no single diagnostic method can detect all active infections and/or trypanosome species or subspecies. The proposed integrative approach will improve the prevention, surveillance and monitoring of animal trypanosomoses with the available diagnostic tools. However, further developments are required to address specific gaps in diagnostic methods and the sustainable control or elimination of these diseases.
Assuntos
Doença de Chagas , Trypanosoma cruzi , Trypanosoma , Tripanossomíase , África/epidemiologia , Animais , Animais Domésticos , Trypanosoma/genética , Tripanossomíase/diagnóstico , Tripanossomíase/epidemiologia , Tripanossomíase/veterináriaRESUMO
BACKGROUND: African animal trypanosomosis (AAT), transmitted by tsetse flies, is arguably the main disease constraint to integrated crop-livestock agriculture in sub-Saharan Africa, and African heads of state and governments adopted a resolution to rid the continent of this scourge. In order to sustainably reduce or eliminate the burden of AAT, a progressive and evidence-based approach is needed, which must hinge on harmonized, spatially explicit information on the occurrence of AAT and its vectors. METHODS: A digital repository was assembled, containing tsetse and AAT data collected in Burkina Faso between 1990 and 2019. Data were collected either in the framework of control activities or for research purposes. Data were systematically verified, harmonized, georeferenced and integrated into a database (PostgreSQL). Entomological data on tsetse were mapped at the level of individual monitoring traps. When this was not possible, mapping was done at the level of site or location. Epidemiological data on AAT were mapped at the level of location or village. RESULTS: Entomological data showed the presence of four tsetse species in Burkina Faso. Glossina tachinoides, present from the eastern to the western part of the country, was the most widespread and abundant species (56.35% of the catches). Glossina palpalis gambiensis was the second most abundant species (35.56%), and it was mainly found in the west. Glossina morsitans submorsitans was found at lower densities (6.51%), with a patchy distribution in the southern parts of the country. A single cluster of G. medicorum was detected (less than 0.25%), located in the south-west. Unidentified tsetse flies accounted for 1.33%. For the AAT component, data for 54,948 animal blood samples were assembled from 218 geographic locations. The samples were tested with a variety of diagnostic methods. AAT was found in all surveyed departments, including the tsetse-free areas in the north. Trypanosoma vivax and T. congolense infections were the dominant ones, with a prevalence of 5.19 ± 18.97% and 6.11 ± 21.56%, respectively. Trypanosoma brucei infections were detected at a much lower rate (0.00 ± 0.10%). CONCLUSIONS: The atlas provides a synoptic view of the available information on tsetse and AAT distribution in Burkina Faso. Data are very scanty for most of the tsetse-free areas in the northern part of the country. Despite this limitation, this study generated a robust tool for targeting future surveillance and control activities. The development of the atlas also strengthened the collaboration between the different institutions involved in tsetse and AAT research and control in Burkina Faso, which will be crucial for future updates and the sustainability of the initiative.
Assuntos
Trypanosoma , Tripanossomíase Africana , Moscas Tsé-Tsé , Animais , Burkina Faso/epidemiologia , Insetos Vetores , Tripanossomíase Africana/epidemiologia , Tripanossomíase Africana/prevenção & controle , Tripanossomíase Africana/veterináriaRESUMO
This review focuses on the most reliable and up-to-date methods for diagnosing trypanosomoses, a group of diseases of wild and domestic mammals, caused by trypanosomes, parasitic zooflagellate protozoans mainly transmitted by insects. In Africa, the Americas and Asia, these diseases, which in some cases affect humans, result in significant illness in animals and cause major economic losses in livestock. A number of pathogens are described in this review, including several Salivarian trypanosomes, such as Trypanosoma brucei sspp. (among which are the agents of sleeping sickness, the human African trypanosomiasis [HAT]), Trypanosoma congolense and Trypanosoma vivax (causing "Nagana" or animal African trypanosomosis [AAT]), Trypanosoma evansi ("Surra") and Trypanosoma equiperdum ("Dourine"), and Trypanosoma cruzi, a Stercorarian trypanosome, etiological agent of the American trypanosomiasis (Chagas disease). Diagnostic methods for detecting zoonotic trypanosomes causing Chagas disease and HAT in animals, as well as a diagnostic method for detecting animal trypanosomes in humans (the so-called "atypical human infections by animal trypanosomes" [a-HT]), including T. evansi and Trypanosoma lewisi (a rat parasite), are also reviewed. Our goal is to present an integrated view of the various diagnostic methods and techniques, including those for: (i) parasite detection; (ii) DNA detection; and (iii) antibody detection. The discussion covers various other factors that need to be considered, such as the sensitivity and specificity of the various diagnostic methods, critical cross-reactions that may be expected among Trypanosomatidae, additional complementary information, such as clinical observations and epizootiological context, scale of study and logistic and cost constraints. The suitability of examining multiple specimens and samples using several techniques is discussed, as well as risks to technicians, in the context of specific geographical regions and settings. This overview also addresses the challenge of diagnosing mixed infections with different Trypanosoma species and/or kinetoplastid parasites. Improving and strengthening procedures for diagnosing animal trypanosomoses throughout the world will result in a better control of infections and will significantly impact on "One Health," by advancing and preserving animal, human and environmental health.
Assuntos
Mal do Coito (Veterinária) , Trypanosoma congolense , Trypanosoma , Tripanossomíase Africana , Tripanossomíase , Animais , Ratos , Trypanosoma/genética , Trypanosoma congolense/genética , Trypanosoma vivax/genética , Tripanossomíase/diagnóstico , Tripanossomíase/epidemiologia , Tripanossomíase/veterinária , Tripanossomíase Africana/parasitologiaRESUMO
Vector-borne diseases affecting livestock have serious impacts in Africa. Trypanosomosis is caused by parasites transmitted by tsetse flies and other blood-sucking Diptera. The animal form of the disease is a scourge for African livestock keepers, is already present in Latin America and Asia, and has the potential to spread further. A human form of the disease also exists, known as human African trypanosomosis or sleeping sickness. Controlling and progressively minimizing the burden of animal trypanosomosis (COMBAT) is a four-year research and innovation project funded by the European Commission, whose ultimate goal is to reduce the burden of animal trypanosomosis (AT) in Africa. The project builds on the progressive control pathway (PCP), a risk-based, step-wise approach to disease reduction or elimination. COMBAT will strengthen AT control and prevention by improving basic knowledge of AT, developing innovative control tools, reinforcing surveillance, rationalizing control strategies, building capacity, and raising awareness. Knowledge gaps on disease epidemiology, vector ecology and competence, and biological aspects of trypanotolerant livestock will be addressed. Environmentally friendly vector control technologies and more effective and adapted diagnostic tools will be developed. Surveillance will be enhanced by developing information systems, strengthening reporting, and mapping and modelling disease risk in Africa and beyond. The socio-economic burden of AT will be assessed at a range of geographical scales. Guidelines for the PCP and harmonized national control strategies and roadmaps will be developed. Gender equality and ethics will be pivotal in all project activities. The COMBAT project benefits from the expertise of African and European research institutions, national veterinary authorities, and international organizations. The project consortium comprises 21 participants, including a geographically balanced representation from 13 African countries, and it will engage a larger number of AT-affected countries through regional initiatives.
RESUMO
BACKGROUND: The main challenge to the successful mass-rearing of the tsetse fly in insectaries, especially in Africa, is a sustainable supply of high-quality blood meals. As such, the collection of high-quality blood in large quantities can be an important constraint to production. One possible strategy to lessen the impact of this constraint is to modify the blood-feeding frequency. In the study reported here, we evaluated the effect of three blood-feeding frequencies on the colony performance of Glossina palpalis gambiensis, a riverine tsetse fly species. METHODS: The effect of three, four and six blood-feedings per week on female survival and productivity were evaluated over a 30-day period. Progeny emergence rate and flight ability were also evaluated. RESULTS: Female survival was significantly higher in flies fed four times per week (87%) than in those fed three (72%) and six times per week (78%; P < 0.05). Productivity was similar between flies fed four and six times per week (457 and 454 larvae) but significantly reduced in flies fed three times per week (280 larvae produced; P < 0.05). Both emergence rate and flight ability rate were also similar between flies fed four times per week (97 and 94%, respectively) and six times per week (96 and 97%, respectively), but they were significantly reduced when flies were fed three times per week (89 and 84%, respectively; P < 0.05). CONCLUSIONS: Blood-feeding frequency could be reduced from six times per week to four times per week without affecting mass-rearing production and progeny quality. The implications of these results on tsetse mass-rearing production are discussed.
Assuntos
Sangue , Comportamento Alimentar , Moscas Tsé-Tsé/fisiologia , Animais , Feminino , Larva/fisiologia , Gado/sangue , Gado/parasitologia , Masculino , Pupa/fisiologia , ReproduçãoRESUMO
Our understanding of the viral communities associated to animals has not yet reached the level attained on the bacteriome. This situation is due to, among others, technical challenges in adapting metagenomics using high-throughput sequencing to the study of RNA viromes in animals. Although important developments have been achieved in most steps of viral metagenomics, there is yet a key step that has received little attention: the library preparation. This situation differs from bacteriome studies in which developments in library preparation have largely contributed to the democratisation of metagenomics. Here, we present a library preparation optimized for metagenomics of RNA viruses from insect vectors of viral diseases. The library design allows a simple PCR-based preparation, such as those routinely used in bacterial metabarcoding, that is adapted to shotgun sequencing as required in viral metagenomics. We first optimized our library preparation using mock viral communities and then validated a full metagenomic approach incorporating our preparation in two pilot studies with field-caught insect vectors; one including a comparison with a published metagenomic protocol. Our approach provided a fold increase in virus-like sequences compared to other studies, and nearly-full genomes from new virus species. Moreover, our results suggested conserved trends in virome composition within a population of a mosquito species. Finally, the sensitivity of our approach was compared to a commercial diagnostic PCR for the detection of an arbovirus in field-caught insect vectors. Our approach could facilitate studies on viral communities from animals and the democratization of metagenomics in community ecology of viruses.
Assuntos
Biblioteca Gênica , Metagenômica , Vírus de RNA , Viroma , Animais , Genoma Viral , Metagenoma , Vírus de RNA/genéticaRESUMO
BACKGROUND: Host-vector contact is a key factor in vectorial capacity assessment and thus the transmission of mosquito-borne viruses such as Rift Valley Fever (RVF), an emerging zoonotic disease of interest in West Africa. The knowledge of the host-feeding patterns of vector species constitutes a key element in the assessment of their epidemiological importance in a given environment. The aim of this work was to identify the blood meal origins of the mosquito Aedes vexans arabiensis, the main vector of RVF virus in the Ferlo pastoral ecosystem of Senegal. METHODOLOGY/PRINCIPAL FINDINGS: Engorged female mosquitoes were collected in Younouféré in the pastoral ecosystem in the Ferlo region during the 2014 rainy season. CO2-baited CDC light traps were set at six points for two consecutive nights every month from July to November. Domestic animals present around traps were identified and counted for each trapping session. Blood meal sources of engorged mosquitoes were identified using a vertebrate-specific multiplexed primer set based on cytochrome b. Blood meal sources were successfully identified for 319 out of 416 blood-fed females (76.68%), of which 163 (51.1%) were single meals, 146 (45.77%) mixed meals from two different hosts and 10 (3.13%) mixed meals from three different hosts. Aedes vexans arabiensis fed preferentially on mammals especially on horse compared to other hosts (FR = 46.83). Proportions of single and mixed meals showed significant temporal and spatial variations according to the availability of the hosts. CONCLUSION: Aedes vexans arabiensis shows an opportunistic feeding behavior depending on the host availability. This species fed preferentially on mammals especially on horses (primary hosts) and ruminants (secondary hosts).