Role of eosinophils in the regulation of H. contortus infection in sheep

Les éosinophiles sont des cellules effectrices recrutées dans le sang et dans les tissus lors d'infestations par des helminthes. Nos études expérimentales avaient pour but d'explorer le rôle de ces cellules dans la résistance des moutons à Haemonchus contortus. In vitro, les éosinophiles de mouton étaient capables de tuer des larves infestantes d'H. contortus en présence de sérum immun ou non. Dans les études in vivo, (1) les infestations expérimentales étaient accompagnées par une réponse immune de type Th2, plus prononcée et plus soutenue dans le temps chez une race résistante que dans une race sensible, (2) les corrélations entre les éosinophilies sanguine et tissulaire d'une part et les paramètres parasitologiques d'autre part étaient positives 15 jours puis négatives 30 jours post-infestation, (3) dans les premiers jours d'une primo-infestation, la participation des éosinophiles dans le rejet des larves semblait minimale, (4) le développement des vers et la fécondité des vers femelles étaient réduites dans un environnement riche en éosinophiles sanguins et tissulaires. L'ensemble de ces résultats indique que les éosinophiles participent à la réponse immune des moutons infestés par H. contortus. Cependant, leur importance relative en présence d'autres éléments de la réponse immune dépend de facteurs comme la présence de complément et d'anticorps spécifiques, de la durée et de la fréquence des expositions au parasite. ABSTRACT : Eosinophils are effector cells that are consistently recruited in both blood and infected tissues during helminth infections. Experimental studies in this thesis explore the role of eosinophils in the resistance to H. contortus infection in sheep. Our results from in vitro studies show that sheep eosinophils are capable of killing H. contortus infective larvae in the presence of immune or non-immune sera. Data from the series of experimental infections undertaken in the course of our studies indicate the following observations: (1) H. contortus infection causes Th2-biazed immune response, which is more pronounced in a resistant breed, (2) correlations between blood and tissue eosinophilia and parasitological parameters were time-dependent, positive two weeks and negative 30 days post-infection, (3) in the early primary infection, the involvement of eosinophils in parasite rejection appears minimal, as tissue recruitment is a relatively late phenomenon and (4) worm development and fecundity are reduced when infections occur in an environment where blood and tissue eosinophilia are high. These results collectively indicate that eosinophils definitely involve in the innate and acquired resistance to H. contortus infection in sheep, but their relative importance in the presence of other immune components, appears to depend on factors such as availability of complement and specific antibody systems, and duration and frequency of infectio

Comparative clinico-haematological analysis in young Zebu cattle experimentally infected with Trypanosoma vivax isolates from tsetse infested and non-tsetse infested areas of Northwest Ethiopia

Background: Ethiopia, particularly in the Northwest region, is affected by both tsetse and non-tsetse fly transmitted trypanosomosis, with significant impact on livestock productivity. The aim of this study was to determine and compare clinical findings and haematological values between experimental infections induced by Trypanosoma vivax isolates from areas of either transmission mode. Sixteen young (aged between 6 and 12 months) Zebu cattle (Bos indicus), purchased from a trypanosome-free area and confirmed to be trypanosome-negative, were randomly assigned into four groups of four animals. Groups 1, 2 and 3 were infected with an isolate from a tsetse infested or one of two isolates from a non-tsetse infested area, and group 4 was a non-infected control. All animals in the infected groups were inoculated intravenously with 2 × 106 trypanosomes from donor animals. The experimental animals were monitored for eight consecutive weeks post infection for clinical signs, parasitaemia and haematological changes in packed cell volume (PCV), haemoglobin concentration (Hgb), total red blood cell (RBC) and white blood cell (WBC) counts, differential WBC count and blood indices (mean corpuscular volume [MCV], mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration).<p></p> Results: Infection was characterized by reduced feed intake, weakness, pyrexia, parasitaemia, rough hair coat, enlarged prescapular lymph nodes, lacrimation, weight loss, pallor mucus membrane and dehydration. Body weight loss in all infected groups was significantly higher than in the non-infected control. Similarly, body weight loss was higher (P < 0.001) in animals infected with the tsetse infested isolate than with the non-tsetse infested isolates. The mean PCV, Hgb, total RBC and WBC counts were lower (P < 0.001), and mean MCV was higher (P = 0.01) in all infected groups than in non-infected control animals at different time points during the study period. Except for minor variations in haematological values, the overall changes were similar in all infected groups.<p></p> Conclusion: Clinical signs and significant reduction in haematological values in the infected groups indicated the pathogenicity of the T. vivax parasites. Pathogenicity of T. vivax from the non-tsetse infested area can be considered as nearly as important as that of its counterpart derived from the tsetse infested area

Occurrence and fertility rates of hydatid cysts in sheep and goats slaughtered at Modjo Luna Export Slaughter House, Ethiopia

In Ethiopia very limited studies were conducted in small ruminant hydatidosis compared to cattle. A cross-sectional study was conducted at Modjo Luna Export Slaughter House from December 2009 to February 2010 to determine the prevalence and fertility of hydatid cysts. A total of 325 sheep and 440 goats were examined. Examination of lung, liver, kidney, heart and carcass was conducted following standard postmortem procedures. Fertility of hydatid cysts was tested by absence or presence of motility and staining with 0.1% aqueous eosin solution. Out of 325 sheep and 440 goats examined 25 (7.7%) sheep and 27(6.13%) goats had hydatid cysts. The prevalence was high in sheep compared to goats although the difference was not statistically significant (P > 0.05). The organ distribution of hydatid cyst in sheep was 15 (60%) in lung, 9 (36%) in liver and 1 (4%) both the liver and lungs. In goats, hydatid cysts were recovered from 19 (70%) of the lung, 5 (18.5%) of the liver, 1 (3.7%) of the kidney, 2 (7.4%) of the heart and 2 (7.4%) of the muscle. In both sheep and goats the infection was more in lungs, followed by liver. Eighty percent of the cysts found in the lung of sheep were fertile, while there was no fertile cyst detected in the lung of goats and the difference was statistically significant (P < 0.05). In Ethiopia, to break the life cycle of echinococcosis/hydatidosis, public education on habit of feeding condemned organs to dogs should be undertaken

Bovine trypanosomosis and its vectors: prevalence and control operations in Kellem Wollega, Western Ethiopia

A cross-sectional study was conducted to estimate the prevalence of bovine trypanosomosis and to assess farmers’ perception of the  disease and its control operations. From October to April 2012, a total of 586 cattle were sampled for the prevalence study. Buffy coat procedure and haematocrit value determination were performed. To capture the fly that was involved in the transmission dynamics, one hundred monopyramidal traps were deployed for 72 hours. A semi-structured questionnaire was conducted to study farmers’  perceptions of the diseases and their control operations. Trypanosomal infections were diagnosed in only 8.7 % (51) of animals. The overall prevalence of trypanosome infection in cattle was significantly varied between study districts (33.1% Dale Sadi and 66.9% Dale Wabera). Most  infections were due to Trypanosoma congolense (81.8%) followed by T. vivax (15.6%) and mixed infections (2.6%). The association of hematological value changes and trypanosome infections was profound. The overall Packed Cell Volume (PCV) values of sampled cattle were 25.8%. A significant (P< 0.05) variation in PCV values was recorded in infected (20.8%) and non-infected (26.5%) cattle. In the study period, a total of 2055 flies were captured and of which 92% belong to the genus Glossina followed by Stomoxys and Tabanids. Four types of tsetse species (G. pallidpes, G. m. morsitans, G. tachinoides, and G. f. fuscipes) were identified. The questionnaire survey revealed that trypanosomosis is the most important problem for agricultural activity and animal production in the study areas. Farmers are well aware of the problem, means of transmission, and the different control methods. Integrating tsetse control program with other trypanosomosis control options is recommended

Cryptosporidium Infections in Africa—How Important Is Zoonotic Transmission? A Review of the Evidence

Cryptosporidium, a protozoan parasite in the phylum Apicomplexa, is the etiological agent of cryptosporidiosis, an intestinal infection characterized by profuse watery diarrhea. Over 30 species of Cryptosporidium are recognized, some host specific whereas others infect a broader host range. Cryptosporidium hominis and Cryptosporidium parvum are the species most commonly associated with human infection; C. hominis is largely associated only with human infections, but C. parvum is also associated with infection in animals, especially young ruminants. In some regions, cryptosporidiosis is a serious veterinary problem, particularly for calves, and lambs. Many outbreaks of human cryptosporidiosis have been associated with zoonotic transmission following contact with infected animals. In Africa, where cryptosporidiosis is a major contributor to pediatric morbidity and mortality, evidence suggests transmission is principally anthroponotic. Given the frequent close contact between humans and animals in Africa, the apparent predominance of human-to-human transmission is both interesting and puzzling. In this article, after a brief “text book” introduction to the parasite, we consider in separate sections the different aspects of relevance to Cryptosporidium transmission in African countries, describing different aspects of the various species and subtypes in human and animal infections, considering livestock management practices in different African countries, and looking for any characteristic “hot spots” where zoonotic transmission has apparently occurred. Studies where transmission networks have been investigated are particularly relevant. Finally, in a separate section, we try to gather these different strands of evidence together in order to assess the reasons behind the apparent predominance of anthroponotic transmission in Africa. Reviewing the available evidence provides an opportunity to re-think transmission pathways, not only in Africa but also elsewhere, and also to pose questions. Does the predominance of human-to-human transmission in Africa reflect a relative absence of zoonotic C. parvum in African livestock? Are Africans less susceptible to zoonotic Cryptosporidium infection, perhaps resulting from early immunostimulation by C. hominis or due to inherent genetic traits? Is the African environment—in all its variety—simply more detrimental to oocyst survival? Will the so-called hypertransmissible subtypes, currently relatively rare in Africa, be introduced from Europe or elsewhere, and, if so, will they fade out or establish and spread? Our intention with this manuscript is not only to summarize and consolidate diverse data, thereby providing an overview of data gaps, but also to provide food for thought regarding transmission of a parasite that continues to have a considerable impact on both human and animal health.publishedVersio

Biomedical waste disposal systems of health facilities in Ethiopia

Background: Biomedical waste generated from health and health-related activities can be grouped as general waste and hazardous waste. This remains true if and only if there is proper on-site handling, such as the segregation and separation of waste based on the type and nature of the source. Methods: A stratified random sampling design was used to provide representative results for Ethiopia, for various types of facility and management authorities, and for each of the 11 regions. Totally, 1327 health facilities were assessed using the World Health Organization (WHO) inventory tools. Results: Nationally, medical waste in 32.6% of the studied health facilities was stored in covered containers, and in about 27% of them it was stored in another protected environment. About 40% of health facilities stored their medical waste in unprotected areas. Twenty-eight (2.6%) and 420 (39.3%) health facilities used 2-chamber industrial incinerators and 1-chamber drum incinerators, respectively. About 58% of health facilities used unsafe waste treatment methods. The proportion of using safe medical waste disposal method was high in referral hospitals (87.9%). This shows the utilization of safe medical waste disposal methods is in decreasing order from higher to lower levels of organization in health facilities. Conclusion: The present study showed a preliminary finding on the waste disposal systems of health facilities at the national level. Dumping biomedical waste outside the health facility is common, and access to common waste facilities is limited. Therefore, a holistic approach to safe medical waste management practices, including the collection process (handling, sorting, and segregation), storage, treatment and final disposal is crucial in all types of health facilities, regardless of the level of organization, ownership, or geographic distribution. Keywords: Health Facility, Biomedical Waste, Disposal, Incinerator, Ethiopi