Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 5 de 5
Mais filtros

Base de dados
Intervalo de ano de publicação
Parasit Vectors ; 13(1): 467, 2020 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-32917242


BACKGROUND: Phlebotomus pedifer is the vector for Leishmania aethiopica causing cutaneous leishmaniasis (CL) in southwestern Ethiopia. Previous research on the transmission dynamics of CL resulted in recommendations for vector control. In order to target these interventions towards affected areas, a comprehensive understanding of the spatial distribution of P. pedifer at high spatial resolution is required. Therefore, this study determined the environmental predictors that facilitate the distribution of P. pedifer and created a map indicating the areas where conditions are suitable for survival of the vector in southwestern Ethiopia with high spatial resolution. METHODS: Phlebotomus pedifer presence points were collected during two entomological surveys. Climate, vegetation and topographic variables were assembled. Climate variables were interpolated with variables derived from high-resolution digital elevation models to generate topoclimatic layers representing the climate conditions in the highlands. A Maximum Entropy model was run with the presence points, predicting variables and background points, which were selected based on a bias file. RESULTS: Phlebotomus pedifer was the only captured Phlebotomus species in the study area and was collected at altitudes ranging between 1685 and 2892 m. Model projections indicated areas with suitable conditions in a 'belt' surrounding the high mountain peaks. Model performance was high, with train and test AUC values being 0.93 and 0.90, respectively. A multivariate environmental similarity surface (MESS) analysis showed that the model projection was only slightly extrapolated for some of the variables. The mean annual temperature was the environmental variable, which contributed most to the model predictions (60.0%) followed by the seasonality in rainfall (13.2%). Variables representing steep slopes showed very low importance to model predictions. CONCLUSIONS: Our findings indicate that the suitable habitats for P. pedifer correspond well with the altitudes at which CL was reported previously, but the predictions are more widely distributed, in contrast with the description of CL to occur in particular foci. Moreover, we confirm that vector distribution is driven by climate factors, suggesting inclusion of topoclimate in sand fly distribution models. Overall, our model provides a map with a high spatial resolution that can be used to target sand fly control measures in southwestern Ethiopia.

Parasit Vectors ; 13(1): 322, 2020 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-32571402


BACKGROUND: The success of indoor interventions that target mosquitoes for malaria control is partially dependent on early evening and outdoor biting behaviours of mosquito vectors. In southwest Ethiopia, people and cattle live in proximity, which calls to investigate whether the presence of cattle increase or decrease bites from malaria mosquito vectors. This study assessed both host-seeking and overnight activity of malaria mosquito vectors given the presence or absence of cattle in Chano Mille village, Arba Minch district, Ethiopia. METHODS: Anopheles species density and activity time was compared when a calf was: (i) placed inside; (ii) 1 m away from; or (iii) absent from a tent with a human volunteer resting insides using hourly human landing catches (HLC) conducted from 18:00-0:00 h for 3 months. This trial was performed close to the shore of the Lake Abaya to minimize the interference of other animals on mosquito movement. The overnight activity of malaria vectors was assessed within a Chano village from 18:00-6:00 h with collections carried out both indoors and outdoors by HLC. Generalized estimating equations were used to statistically assess differences. RESULTS: Anopheles pharoensis was significantly more prevalent when a calf was present either inside (42%, P < 0.001), or adjacent to (46%, P = 0.002) a tent relative to a tent without a calf present. The presence of a calf did not affect densities of the primarily anthropophilic species A. gambiae (s.l.), or An. tenebrosus. Anopheles gambiae (s.l.) (P < 0.001) and An. pharoensis (P = 0.015) both had a tendency for early evening biting between 19:00 h and 20:00 h. Anopheles gambiae (s.l.) was mainly biting humans outdoors in the village. CONCLUSIONS: The presence of calves within and close to human dwellings acts to draw malaria mosquitoes toward the human occupant with the potential to increase their risk of malaria. Hence, deployment of cattle far from human residence could be recommended to reduce human exposure. Outdoor and early evening biting could threaten the success of current indoor-based interventions. Hence, tools could be designed to reduce this threat.

Parasit Vectors ; 13(1): 276, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32487217


BACKGROUND: In eco-epidemiological studies, Leishmania detection in vectors and reservoirs is frequently accomplished by high-throughput and sensitive molecular methods that target minicircle kinetoplast DNA (kDNA). A pan-Leishmania SYBR green quantitative PCR (qPCR) assay which detects the conserved spliced-leader RNA (SL RNA) sequence was developed recently. This study assessed the SL RNA assay performance combined with a crude extraction method for the detection of Leishmania in field-collected and laboratory-reared sand flies and in tissue samples from hyraxes as reservoir hosts. METHODS: Field-collected and laboratory-infected sand fly and hyrax extracts were subjected to three different qPCR approaches to assess the suitability of the SL RNA target for Leishmania detection. Nucleic acids of experimentally infected sand flies were isolated with a crude extraction buffer with ethanol precipitation and a commercial kit and tested for downstream DNA and RNA detection. Promastigotes were isolated from culture and sand fly midguts to assess whether there was difference in SL RNA and kDNA copy numbers. Naive sand flies were spiked with a serial dilution of promastigotes to make a standard curve. RESULTS: The qPCR targeting SL RNA performed well on infected sand fly samples, despite preservation and extraction under presumed unfavorable conditions for downstream RNA detection. Nucleic acid extraction by a crude extraction buffer combined with a precipitation step was highly compatible with downstream SL RNA and kDNA detection. Copy numbers of kDNA were found to be identical in culture-derived parasites and promastigotes isolated from sand fly midguts. SL RNA levels were slightly lower in sand fly promastigotes (ΔCq 1.7). The theoretical limit of detection and quantification of the SL RNA qPCR respectively reached down to 10-3 and 10 parasite equivalents. SL RNA detection in stored hyrax samples was less efficient with some false-negative assay results, most likely due to the long-term tissue storage in absence of RNA stabilizing reagents. CONCLUSIONS: This study shows that a crude extraction method in combination with the SL RNA qPCR assay is suitable for the detection and quantification of Leishmania in sand flies. The assay is inexpensive, sensitive and pan-Leishmania specific, and accordingly an excellent assay for high-throughput screening in entomological research.

BMC Res Notes ; 12(1): 700, 2019 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-31655627


OBJECTIVE: To assess the effect of comprehensive sexuality education on the comprehensive knowledge and attitude to condom use among first-year students at Arba Minch University. RESULTS: A total of 832 students participated at a baseline, and 820 students participated at the posttest. This study found that there was a significant effect on changing students' knowledge and attitude towards a condom. In the education group, the students' average change of comprehensive condom knowledge score was 0.229 higher than the average score of students' in the control group (ATE = 0.229, 95% CI 0.132 to 0.328; p < 0.001). The average change of attitude toward condom score of students' in the education group was 1.834 higher than the average change score of students' in the control group (ATE = 1.834, 95% CI 1.195 to 2.772; p < 0.001).This study provides further evidence on the effectiveness of comprehensive sexuality education in terms of knowledge and attitude towards a condom. Therefore, the implementation of this education should be strengthened in order the prevent youths from STI/HIV and unintended pregnancies.

Conhecimentos, Atitudes e Prática em Saúde , Sexo Seguro/estatística & dados numéricos , Educação Sexual/estatística & dados numéricos , Comportamento Sexual/estatística & dados numéricos , Estudantes/estatística & dados numéricos , Universidades , Adolescente , Preservativos , Etiópia , Feminino , Humanos , Masculino , Gravidez , Gravidez não Desejada/psicologia , Sexo Seguro/psicologia , Educação Sexual/métodos , Comportamento Sexual/psicologia , Estudantes/psicologia , Inquéritos e Questionários , Adulto Jovem
PLoS Negl Trop Dis ; 13(8): e0007667, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31425506


BACKGROUND: Ochollo is a village in southern Ethiopia burdened with cutaneous leishmaniasis (CL), where Phlebotomus pedifer is the only vector for Leishmania aethiopica and hyraxes are confirmed reservoir hosts. A detailed description of the different players of transmission, and the ecology and seasonality of the vector needs to be established in order to accomplish efficient control programs. METHODS AND FINDINGS: Between March 2017 and February 2018, a monthly sandfly collection was carried out in different habitats and records of temperature and humidity were taken. Rodents and hyraxes were trapped in the dry and wet season. All samples were screened for Leishmania kinetoplast DNA (kDNA). Positive samples were further processed for determination of the Leishmania species and the species of the sandfly/small mammal that was found infected. Additionally, the species of 400 sandfly specimens from different habitats and seasons was identified. 17,190 Sergentomyia and Phlebotomus sandflies were caught and showed an overall kDNA prevalence of 2.6%, all were L. aethiopica infections only found in P. pedifer. The overall sandfly and P. pedifer abundance peaked in the dry season and was negatively correlated with the %RH. The kDNA prevalence varied over the months and was negatively correlated with the temperature. Total sandfly abundance did not differ between the sampled habitats, but P. pedifer was the distinct predominant species only in caves. Moreover, significantly more infected sandflies were found in caves. Only 1/192 rodents were kDNA positive, while 20.0% (5/25) of Heterohyrax brucei were found infected. CONCLUSIONS: This study suggests that caves may be a source of multiplication of the infection. If an outdoor control program would be considered, it would be useful to focus on caves in the wet season, when the sandfly abundance is lowest. The captured rodent species appear not important for transmission and the contribution of hyraxes in transmission should be further investigated.

DNA de Protozoário/análise , Reservatórios de Doenças , Vetores de Doenças , Procaviídeos/parasitologia , Leishmania/genética , Leishmaniose Cutânea/epidemiologia , Psychodidae/parasitologia , Animais , DNA de Protozoário/genética , Transmissão de Doença Infecciosa , Etiópia/epidemiologia , Feminino , Humanos , Umidade , Leishmaniose Cutânea/transmissão , Masculino , Carga Parasitária , Prevalência , Psychodidae/crescimento & desenvolvimento , Estações do Ano , Temperatura