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Foot and mouth disease in Zambia: Spatial and temporal distributions of outbreaks, assessment of clusters and implications for control
2014
Yona Sinkala | Martin Simuunza | John B. Muma | Dirk U. Pfeiffer | Christopher J. Kasanga | Aaron Mweene
Zambia has been experiencing low livestock productivity as well as trade restrictions owing to the occurrence of foot and mouth disease (FMD), but little is known about the epidemiology of the disease in these endemic settings. The fundamental questions relate to the spatio-temporal distribution of FMD cases and what determines their occurrence. A retrospective review of FMD cases in Zambia from 1981 to 2012 was conducted using geographical information systems and the SaTScan software package. Information was collected from peer-reviewed journal articles, conference proceedings, laboratory reports, unpublished scientific reports and grey literature. A space–time permutation probability model using a varying time window of one year was used to scan for areas with high infection rates. The spatial scan statistic detected a significant purely spatial cluster around the Mbala–Isoka area between 2009 and 2012, with secondary clusters in Sesheke–Kazungula in 2007 and 2008, the Kafue flats in 2004 and 2005 and Livingstone in 2012. This study provides evidence of the existence of statistically significant FMD clusters and an increase in occurrence in Zambia between 2004 and 2012. The identified clusters agree with areas known to be at high risk of FMD. The FMD virus transmission dynamics and the heterogeneous variability in risk within these locations may need further investigation.
显示更多 [+] 显示较少 [-]Distribution patterns and predilection muscles of <i>Trichinella zimbabwensis</i> larvae in experimentally infected Nile crocodiles (<i>Crocodylus niloticus</i> Laurenti)
2014
Louis J. La Grange | Samson Mukaratirwa
No controlled studies have been conducted to determine the predilection muscles of Trichinella zimbabwensis larvae in Nile crocodiles (Crocodylus niloticus) or the influence of infection intensity on the distribution of the larvae in crocodiles. The distribution of larvae in muscles of naturally infected Nile crocodiles and experimentally infected caimans (Caiman crocodilus) and varans (Varanus exanthematicus) have been reported in literature. To determine the distribution patterns of T. zimbabwensis larvae and predilection muscles, 15 crocodiles were randomly divided into three cohorts of five animals each, representing high infection (642 larvae/kg of bodyweight average), medium infection (414 larvae/kg of bodyweight average) and low infection (134 larvae/kg of bodyweight average) cohorts. In the high infection cohort, high percentages of larvae were observed in the triceps muscles (26%) and hind limb muscles (13%). In the medium infection cohort, high percentages of larvae were found in the triceps muscles (50%), sternomastoid (18%) and hind limb muscles (13%). In the low infection cohort, larvae were mainly found in the intercostal muscles (36%), longissimus complex (27%), forelimb muscles (20%) and hind limb muscles (10%). Predilection muscles in the high and medium infection cohorts were similar to those reported in naturally infected crocodiles despite changes in infection intensity. The high infection cohort had significantly higher numbers of larvae in the sternomastoid, triceps, intercostal, longissimus complex, external tibial flexor, longissimus caudalis and caudal femoral muscles (p < 0.05) compared with the medium infection cohort. In comparison with the low infection cohort, the high infection cohort harboured significantly higher numbers of larvae in all muscles (p < 0.05) except for the tongue. The high infection cohort harboured significantly higher numbers of larvae (p < 0.05) in the sternomastoid, triceps, intercostal, longissimus complex, external tibial flexor, longissimus caudalis and caudal femoral muscles compared with naturally infected crocodiles. Results from this study show that, in Nile crocodiles, larvae of T. zimbabwensis appear first to invade predilection muscles closest to their release site in the small intestine before occupying those muscles situated further away. The recommendation for the use of masseter, pterygoid and intercostal muscles as sampling sites for the detection of T. zimbabwensis in crocodiles is in contrast to the results from this study, where the fore- and hind limb muscles had the highest number of larvae. This study also supports the use of biopsy sampling from the dorso-lateral regions of the tail for surveillance purposes in both wild and commercial crocodile populations.
显示更多 [+] 显示较少 [-]Drivers of disease emergence and spread: Is wildlife to blame?
2014
Richard Kock
The global focus on wildlife as a major contributor to emerging pathogens and infectious diseases (EIDs) in humans and domestic animals is not based on field, experimental or dedicated research, but mostly on limited surveys of literature, opinion and the assumption that biodiversity harbours pathogens. The perceived and direct impacts of wildlife, from being a reservoir of certain human and livestock pathogens and as a risk to health, are frequently overstated when compared to the Global burden of disease statistics available from WHO, OIE and FAO. However organisms that evolve in wildlife species can and do spill-over into human landscapes and humans and domestic animal population and, where these organisms adapt to surviving and spreading amongst livestock and humans, these emerging infections can have significant consequences. Drivers for the spill-over of pathogens or evolution of organisms from wildlife reservoirs to become pathogens of humans and domestic animals are varied but almost without exception poorly researched. The changing demographics, spatial distribution and movements, associated landscape modifications (especially agricultural) and behavioural changes involving human and domestic animal populations are probably the core drivers of the apparent increasing trend in emergence of new pathogens and infectious diseases over recent decades.
显示更多 [+] 显示较少 [-]The benefits of ‘One Health’ for pastoralists in Africa
2014
Helena Greter | Vreni Jean-Richard | Lisa Crump | Mahamat Béchir | Idriss O. Alfaroukh | Esther Schelling | Bassirou Bonfoh | Jakob Zinsstag
‘One health’ is particularly suited to serve mobile pastoralists. Dinka pastoralists in Sudan inspired Calvin Schwabe to coin the term ‘one medicine’, indicating that there is no difference in paradigm between human and veterinary medicine. Our contemporary definition of ‘one health’ is any added value in terms of improved health of humans and animals or financial savings or environmental services resulting from a closer cooperation of human and animal health sectors. Here we present a summary of ‘one health’ studies with mobile pastoralists in Africa which were done in research partnership, demonstrating such an added value. Initial joint human and animal health studies revealed higher livestock vaccination coverage than in the pastoralist community, leading to joint animal and human vaccination intervention studies which demonstrated a better access to primary health care services for pastoralists in Chad. Further simultaneous animal and human serological studies showed that camel breeding was associated with human Q-fever seropositivity. In Borana communities in Ethiopia, human cases of Mycobacterium bovis infection could be related to strains isolated from cattle. A challenge remained with regard to how to assess vaccination coverage in mobile populations. With the advent of mobile phones, health and demographic surveillance could be established for mobile pastoralists and their animals. This presents vast possibilities for surveillance and control of human and animal diseases. Pastoralists prefer a ‘one health’ approach and therefore contribute toward the validation of this concept by showing real added value of the cooperation between human and animal health services.
显示更多 [+] 显示较少 [-]Two genotypes of infectious bronchitis virus are responsible for serological variation in KwaZulu-Natal poultry flocks prior to 2012
2014
Adrian D. Knoetze | Niloshni Moodley | Celia Abolnik
This study describes the isolation, serotyping and genotyping of 54 infectious bronchitis virus (IBV) cases predominantly in KwaZulu-Natal and compared to several isolates from other South African provinces between 2011 and 2012 and several historic isolates. The results indicate the division of isolates into two different genotypes of IBV within the province, Massachusetts (Mass)-like and QX-like. The IBV Mass-like genotype was the most prevalent and was detected in 79% of the full spike protein S1 gene sequences. Variation up to 22.3% was detected within local Mass-type strains, supporting the hypothesis that multiple IBV serotypes may co-circulate in the same region simultaneously. Additionally, more conservation was observed amongst Mass serotypes versus QX-like serotypes, implying that vaccine use can influence the variability within the IBV population; this is deduced from the fact that the only live vaccine registered for use in South Africa at the time of the study was of Mass origin and no QX-like vaccines were available for use. This study offers the first published consolidation of IBV isolates from an area of South Africa and identifies variation within the IBV population of the broiler flock within the study area over a 2-year period.
显示更多 [+] 显示较少 [-]Bovine trypanosomosis and its fly vectors in three selected settlement areas of Hawa-Gelan district, western Ethiopia
2014
Kumela Lelisa | Shihun Shimeles | Jemere Bekele | Desie Sheferaw
A cross-sectional study aimed at investigating the species diversity of fly vectors and estimating the prevalence of bovine trypanosomosis was carried out from October 2009 to May 2010 in selected settlement areas of the Hawa-Gelan district in the western Wollega zone of Ethiopia. Standard methods of sampling and identification were employed for both entomological and parasitological examination. Three species of the genus Glossina (Glossina pallidipes, Glossina morsitans submorsitans and Glossina fuscipes) and two genera of biting flies (Stomoxys and Tabanus) were caught and identified. The overall apparent density of Glossina species caught was 10.5 flies per trap per day, with a higher proportion of female flies (57.2%). Out of a total 389 cattle examined, 42 (10.8%; 95% CI: 7.89% – 14.3%) were found infected with trypanosomes. Three trypanosome species were detected in the study area, namely Trypanosoma congolense (54.8%), Trypanosoma brucei (23.8%) and Trypanosoma vivax (21.4%). The prevalence of trypanosomosis was found to be significantly (p < 0.05) higher in cattle with poor body condition. There was an association between mean packed cell volume (PCV) and the occurrence of parasitaemia (χ2 = 49.5, p < 0.05). About 95.2% of cattle that were positive for trypanosomes had a PCV less than the lower limit for cattle. Considering the current result, bovine trypanosomosis seems to be a serious constraint for agricultural activities in the settlement areas of the Hawa-Gelan district and seems to be associated with the presence of Glossina species. Therefore, application of control methods through community involvement to reduce the Glossina species infestation level is likely to increase animal productivity.
显示更多 [+] 显示较少 [-]Comparison of polymerase chain reaction and Warthin-Starry techniques to detect <i>Leptospira</i> spp. in kidneys of slaughtered cattle
2014
Shahrzad Azizi | Reza Kheirandish | Elham Rahimi
Leptospirosis is a worldwide zoonotic disease that is caused by Gram-negative spirochaetes, Leptospira species. Affected animals excrete the organism in the urine into the environment and act as a source of infection. Cattle are maintenance hosts for some serovars of leptospirosis and are important in the transmission of the infection to humans. At post mortem examination, affected cattle show white spots in their kidneys but these are not specific for leptospirosis. Sometimes it is necessary that leptospirosis be diagnosed in the carcass. Different direct methods, including polymerase chain reaction (PCR), Warthin-Starry silver stain (WS), immunofluorescence (IF) and immunohistochemistry (IHC) can be used in order to diagnose leptospirosis in the affected tissues, such as kidney. The main advantage of the WS technique is direct visualisation of the bacteria in the tissue samples. Silver staining is useful for retrospective studies on formalin-fixed and paraffin-embedded samples but little information is available on the sensitivity and specificity of the technique. The present study aimed to find a simple and inexpensive method that can be used in any laboratory and that also, if clinical samples are not available, can detect Leptospira in tissue samples post mortem. This study was performed on 19 paraffin-embedded kidneys of slaughtered cows that grossly had focal to multifocal white spots. Leptospirosis was confirmed in these samples with PCR based on the LipL32 gene. Out of 19 PCR positive kidneys, Leptospira was identified in 13 stained samples by WS. The kidneys revealed different grades of interstitial nephritis. No relationship was found between severity of lesions and presence of leptospires in the kidneys. The PCR results on the urine and blood were consistent with matching WS stained kidneys. Out of 13 kidneys that were positive with silver staining, 7 matching blood and 10 matching urine samples were confirmed positive for leptospirosis with PCR. In this study, the WS technique provided fewer positive results than PCR. This may be as a result of a low burden of Leptospira in the kidney, but the sensitivity of WS staining needs more investigation.
显示更多 [+] 显示较少 [-]Efficiency indices and indicators of poor performance among emerging small-scale pig farmers in the Limpopo Province, South Africa
2014
Japhta M. Mokoele | B. Tom Spencer | Leo A.M.G. van Leengoed | Folorunso O. Fasina
Limpopo is a very important area for pig production in terms of animal populations and contributions to transboundary animal disease spread. Emerging small-scale pig farmers (ESSPF) are being encouraged to establish operations and spread in South Africa; however, for these farmers to perform optimally, they need to understand the basics of animal agriculture and contribute to enhancing biosecurity and efficient production systems. In the present study, the limitations to efficient production amongst ESSPF were evaluated and some improvements were suggested. It was found that the ESSPF are dominated by males and include a large percentage of older persons. A total of 26.54% of these farmers have post-matriculation qualifications. Undefined and indigenous breeds still dominate their animal genetics. The animal health technicians are the preferred channels by which farmers report diseases to the authorities (52.47%) and only one out of five (20.37%) will preferably report a disease situation direct to a veterinarian. These farmers do not vaccinate their stock, and knowledge of biosecurity is poor. Antimicrobials, especially tetracyclines, are abused. Animals that are slaughtered within the community or sold at local sale points, pension pay stations and auction markets are likely candidates for disease spread. It is recommended that the younger generations are retained and incentivised in animal agriculture. Improved training on management, health, biosecurity and better market access must be provided for the ESSPF, whilst efforts should made to consolidate these farmers into small cooperatives. The current government agricultural support system will need to be reworked to benefit the resource-poor farmers. Collaborative efforts in disease reporting and management among veterinarians, animal health technicians and extension officers will become necessary. Finally, the creation of a progressive quality grading system for ESSPF should be planned by the industry and this should be attached to a reward system that will encourage these farmers to target good farming practice.
显示更多 [+] 显示较少 [-]Bovine cysticercosis and its food safety implications in Harari People’s National Regional State, eastern Ethiopia
2014
Yitagele Terefe | Feysel Redwan | Endrias Zewdu
Taenia saginata cysticercosis is one of the zoonotic diseases that threaten food safety and food security, particularly in developing countries. A cross-sectional study was conducted to estimate the prevalence and cyst distribution in infected cattle, and food safety implications of Taenia saginata cysticercosis in Harari People’s National Regional State, eastern Ethiopia. Post-mortem inspection of carcasses and organs of slaughtered cattle in Harar Municipal Abattoir, cyst viability tests and interviews with randomly selected meat consumers were undertaken. The post-mortem inspection showed that of the 898 local zebu cattle slaughtered for human consumption and examined for the presence of cysticerci of T. saginata, 19.7% (177/898; 95% CI = 17.2–22.5) harboured at least one cyst in the muscles or organs inspected. Of the edible anatomical sites with cysticerci, shoulder muscle, liver and heart together represented 65.4%, 66.0% and 65.4% respectively of relative prevalence, total cyst count and cyst viability. These edible sites are preferred above others by local people for preparation and consumption of raw or inadequately cooked meat dishes that are locally served as kurt, kitffo and dullet. The interviews revealed that among the 300 study participants, 182 (60.7%) had been infected by taeniosis at least once during the previous year and of these 99.0% had eaten raw or undercooked beef, the majority (88.3%) obtained from butchers assumed to provide officially inspected meat that was fit for consumption. This indicated that existing meat inspection processes were inadequate to prevent carcasses infected with T. saginata cysticerci from reaching consumers. The high prevalence of viable cysts in the edible parts of beef together with the widespread consumption of raw or undercooked beef indicated the importance of T. saginata cysticercosis as a food safety problem in eastern Ethiopia. The promotion of policies to upgrade existing meat inspection procedures and public education to ensure effective prevention of T. saginata taeniosis in humans were recommended.
显示更多 [+] 显示较少 [-]<i>Coenurus cerebralis</i> cyst in the orbit of a ewe
2014
Mohie Haridy | Madeh Sadan | Mosab Omar | Hiroki Sakai | Tokuma Yanai
A 4-year-old Rahmani breed ewe was presented for surgery to the Veterinary Teaching Hospital, South Valley University, Egypt with enlargement and protrusion of the eye ball, blepharitis and congestion of the conjunctiva. On examination, a cyst 2.5 cm x 3.5 cm in diameter containing sandy fluid was detected in the perioptic nerve fat. Histopathological examination revealed that the epithelial lining of the conjunctiva was necrotic and severely infiltrated by neutrophils. The underlying connective tissue was oedematous, hyperaemic and severely infiltrated by neutrophils. Desquamation of the corneal epithelium was seen, together with oedema of the stroma. The tissue surrounding the cyst was compressed and the lacrimal glands revealed pressure atrophy. The muscular tissue was atrophied and infiltrated by fat cells. The cyst wall was lined with white scolices protruding from the inner wall. Based on the gross and histopathological characteristics of the cyst observed, the cyst was diagnosed as Coenurus cerebralis. This is the first report of orbital coenurosis in a sheep.
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