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Natural hosts of the larvae of <i>Nuttalliella</i> sp. (<i>N. namaqua</i>?) (Acari: Nuttalliellidae)
2012
Ivan G. Horak | Heike Lutermann | Katarina Medger | Dmitry A. Apanaskevich | Conrad A. Matthee
The first collection of unengorged and fully engorged larvae of Nuttalliella sp. (N. namaqua?) from the murid rodents Micaelamys namaquensis, Aethomys chrysophilus and Acomys spinosissimus in Limpopo Province and from M. namaquensis in the Northern Cape Province, South Africa, is documented. A total of nine larvae were collected from two M. namaquensis in the Soutpansberg mountain range in the Limpopo Province during April 2009. During the last week of September 2011, 221 larvae were collected from rodents at the same locality and 10 of 48 M. namaquensis, 6 of 12 Ae. chrysophilus and 3 of 14 Ac. spinosissimus were infested. One of the M. namaquensis harboured 53 larvae. Five larvae were collected from two M. namaquensis in the Northern Cape Province. Total genomic DNA was extracted from two larvae and a region of the 18S rRNA gene was sequenced for these. BLASTn searches revealed similarity between these specimens and the Nuttalliella sequences published on GenBank.
显示更多 [+] 显示较少 [-]Epidemiological aspects of bovine trypanosomosis in an endemic focus of eastern Zambia: The role of trypanosome strain variability in disease pattern
2012
Justin Masumu | G. Tshilenge | V. Mbao
Bovine trypanosomosis displays various epidemiological aspects in various areas. In some instances the disease has a high prevalence in animals with high impact on production whereas in other cases the disease has a low impact on production despite a high level of infection in animals. In addition epidemiological changes are frequently observed in various areas and are related to many factors including the vectors, the host, the parasites, the environment as well as the livestock management. However the implication of these factors in these changes is not fully elucidated. In eastern Zambia, factors predicting the establishment of severe infection in cattle are all present. However trypanosomosis occurring in cattle in this area has a low impact on livestock production. Several studies on the characterisation of trypanosome strains circulating in domestic and wild animals have been conducted in order to clarify the epidemiology of this disease in this area. These studies aimed at evaluating genetic and biological characteristics of these strains including their virulence profiles, their transmissibility by tsetse flies, their resistance to drugs and interference between different strains. In this review these findings are analysed in order to elucidate the implication of trypanosome strain variability in the distribution and the expression of this disease in the study area. The evolutionary trends of the situation occurring in this study area are also explained. Use of these findings is the context of disease control in the study area is further discussed.
显示更多 [+] 显示较少 [-]The African buffalo: A villain for inter-species spread of infectious diseases in southern Africa
2012
Anita L. Michel | Roy G. Bengis
The African buffalo (Syncerus caffer) is a large wild bovid which until recently ranged across all but the driest parts of sub-Saharan Africa, and their local range being limited to about 20 km from surface water. They are of high ecological value due to their important role as bulk feeders in the grazing hierarchy. They also have high economic value, because they are one of the sought after ‘Big Five’ in the eco-tourism industry. In Africa, buffaloes have been recognised for some time as an important role player in the maintenance and transmission of a variety of economically important livestock diseases at the wildlife and/or livestock interface. These include African strains of foot-and-mouth disease (FMD), Corridor disease (theileriosis), bovine tuberculosis and bovine brucellosis. For a number of other diseases of veterinary importance, African buffaloes may also serve as amplifier or incidental host, whereby infection with the causative pathogens may cause severe clinical signs such as death or abortion as in the case of anthrax and Rift Valley fever, or remain mild or subclinical for example heartwater. The long term health implications of most of those infections on the buffalo at a population level is usually limited, and they do not pose a threat on the population’s survival. Because of their ability to harbour and transmit important diseases to livestock, their sustainable future in ecotourism, trade and transfrontier conservation projects become complex and costly and reliable diagnostic tools are required to monitor these infections in buffalo populations.
显示更多 [+] 显示较少 [-]Ectoparasites of sheep in three agro-ecological zones in central Oromia, Ethiopia
2012
Bersissa Kumsa | Kebede Beyecha | Mesula Geloye
A cross-sectional study was conducted to determine the prevalence and risk factors for ectoparasites infestation in sheep in three agro-ecological zones in central Oromia, Ethiopia, from October 2009 to April 2010. The study revealed that 637 (48.1%) of the 1325 sheep examined were infested with one or more ectoparasites. The ectoparasites identified were <em>Bovicola ovis</em> (27.2%), <em>Melophagus ovinus</em> (16.4%), <em>Ctenocephalides</em> sp. (2.3%), <em>Linognathus africanus</em> (1.2%), <em>Linognathus ovillus </em> (0.3%),<em> Sarcoptes</em> sp. (1.2%), <em>Amblyomma variegatum</em> (4.4%), <em>Rhipicephalus evertsi evertsi</em> (1.9%), <em>Rhipicephalus pravus</em> (1.9%), <em>Rhipicephalus</em> (<em>Boophilus</em>) <em>decoloratus</em> (1.1%), <em>Rhipicephalus sanguineus</em> (0.9%), <em>Rhipicephalus praetextatus</em> (1.1%) and <em>Hyalomma truncatum</em> (1.6%). Statistically significant difference was observed in prevalence of <em>B. ovis</em> amongst study agroecological zones: highland 36.6%, midland 20.9% and lowland 14.0%. Significantly higher prevalence was recorded in highland agroecological zone. A significantly (OR = 0.041, <em>p</em> < 0.001) higher prevalence of <em>M. ovinus</em> in the highland (31.7%) than in both the lowland (0%) and midland (1.9%) was observed. The risk of tick infestation in the lowland and midland was 9.883 times and 13.988 times higher than the risk in the highland, respectively. A significantly higher prevalence of <em>Ctenocephalides</em> species was encountered in both the lowland (OR = 4.738, <em>p</em> = 0.011) and midland (OR = 8.078, <em>p</em> = 0.000) than in the highland agro-ecological zone. However, a significant difference (<em>p</em> = 0.191) amongst agro-ecological zones was not found for the prevalence of <em>Linognathus</em> and <em>Sarcoptes </em>species. Statistically significant variation (<em>p</em> > 0.05) was never recorded in the prevalence of all the identified species of ectoparasites between male and female sheep hosts. However, a significantly (<em>p</em> = 0.006) higher prevalence of<em> B. ovis</em> was recorded between young and adult sheep. The risk of <em>B. ovis</em> infestation was 1.45 times higher in young than the adult sheep. Furthermore, a significantly (<em>p</em> < 0.001) higher prevalence of <em>M. ovinus</em>, <em>B. ovis</em> and <em>Sarcoptes</em> sp. was found between sheep with poor and a good body condition. The ever increasing threat of ectoparasites on overall sheep productivity and tanning industry in Ethiopia warrants urgent control intervention. Further studies on the role of ectoparasites in transmission of diseases to sheep, zoonotic importance, comparative prevalence and load, and the importance of sheep as alternative hosts in different agroecological zones, breeds and management systems in Ethiopia are recommended so as to design applicable control programme in the country.
显示更多 [+] 显示较少 [-]MSc One Health Analytical Epidemiology
2012
Martin C. Simuunza
Filoviral haemorrhagic fevers: A threat to Zambia?
2012
Katendi Changula | A.S. Mweene
Filoviral haemorrhagic fevers (FVHF) are caused by agents belonging to Filoviridae family, Ebola and Marburg viruses. They are amongst the most lethal pathogens known to infect humans. Incidence of FVHF outbreaks are increasing, with affected number of patients on the rise. Whilst there has been no report yet of FVHF in Zambia, its proximity to Angola and Democratic Republic of Congo, which have recorded major outbreaks, as well as the open borders, increased trade and annual migration of bats between these countries, puts Zambia at present and increased risk. Previous studies have indicated bats as potential reservoir hosts for filoviruses. An increasing population with an increasing demand for resources has forced incursion into previously uninhabited land, potentially bringing them into contact with unknown pathogens, reservoir hosts and/or amplifying hosts. The recent discovery of a novel arenavirus, Lujo, highlights the potential that every region, including Zambia, has for being the epicentre or primary focus for emerging and re-emerging infections. It is therefore imperative that surveillance for potential emerging infections, such as viral haemorrhagic fevers be instituted. In order to accomplish this surveillance, rapid detection, identification and monitoring of agents in patients and potential reservoirs is needed. International co-operation is the strategy of choice for the surveillance and fight against emerging infections. Due to the extensive area in which filoviral infections can occur, a regional approach to surveillance activities is required, with regional referral centres. There is a need to adopt shared policies for the prevention and control of infectious diseases. There is also need for optimisation of currently available tests and development of new diagnostic tests, in order to have robust, highly sensitive and specific diagnostic tests that can be used even where there are inadequate laboratories and diagnostic services.
显示更多 [+] 显示较少 [-]Leptospirosis in South Africa
2012
Adrienne Saif | John Frean | Jenny Rossouw | Anastasia N. Trataris
Leptospirosis is a common zoonosis worldwide. It has a ubiquitous distribution and causes a wide spectrum of disease. Leptospirosis therefore has a broad reservoir host range, and many infected species of animals excrete leptospires in their urine, which leads to contamination of soil and water. Typical descriptions of the disease include a biphasic (anicteric form) and fulminant disease in the icterohaemorrhagic form. Only a few local case reports of human leptospirosis have been published, the most recent one being in 1974. A rodent-related zoonosis study (RatZooMan) was conducted from 2003 until 2006 in three provinces (Limpopo, KwaZulu-Natal and the Eastern Cape). Of the people sampled in Cato Crest (Durban, KwaZulu-Natal Province), 43/217 (19.8%) were seropositive for leptospirosis. Of the clinical samples sent to the Special Bacterial Pathogens Reference Unit from all over the country for testing in 2009, 16/176 (9%) were IgM positive; in 2010 and January 2011 to May 2011, 14/215 (6.5%) and 12/96 (12.5%), respectively, were IgM positive. The apparent incidence of leptospirosis in the South African population is moderately high based on the detected positives in suspected cases; it is thought that the circulating infection rate may be even higher when looking at the RatZooMan results. This may be due to underreporting and undiagnosed cases. Communities in informal settlements in urban areas are especially at risk as infected rodent populations are a continuous source of transmission.
显示更多 [+] 显示较少 [-]Ebola virus outbreaks in Africa: Past and present
2012
J.J. Muyembe-Tamfum | S. Mulangu | Justin Masumu | J.M. Kayembe | A. Kemp | Janusz T. Paweska
Ebola haemorrhagic fever (EHF) is a zoonosis affecting both human and non-human primates (NHP). Outbreaks in Africa occur mainly in the Congo and Nile basins. The first outbreaks of EHF occurred nearly simultaneously in 1976 in the Democratic Republic of the Congo (DRC, former Zaire) and Sudan with very high case fatality rates of 88% and 53%, respectively. The two outbreaks were caused by two distinct species of Ebola virus named Zaire ebolavirus (ZEBOV) and Sudan ebolavirus (SEBOV). The source of transmission remains unknown. After a long period of silence (1980–1993), EHF outbreaks in Africa caused by the two species erupted with increased frequency and new species were discovered, namely Côte d’Ivoire ebolavirus (CIEBOV) in 1994 in the Ivory Coast and Bundibugyo ebolavirus (BEBOV) in 2007 in Uganda. The re-emergence of EHF outbreaks in Gabon and Republic of the Congo were concomitant with an increase in mortality amongst gorillas and chimpanzees infected with ZEBOV. The human outbreaks were related to multiple, unrelated index cases who had contact with dead gorillas or chimpanzees. However, in areas where NHP were rare or absent, as in Kikwit (DRC) in 1995, Mweka (DRC) in 2007, Gulu (Uganda) in 2000 and Yambio (Sudan) in 2004, the hunting and eating of fruit bats may have resulted in the primary transmission of Ebola virus to humans. Human-to-human transmission is associated with direct contact with body fluids or tissues from an infected subject or contaminated objects. Despite several, often heroic field studies, the epidemiology and ecology of Ebola virus, including identification of its natural reservoir hosts, remains a formidable challenge for public health and scientific communities.
显示更多 [+] 显示较少 [-]Theileriosis (Cytauxzoonosis) in Roan antelope (<i>Hippotragus equinus</i>): Field exposure to infection and identification of potential vectors
2012
Johan C.A. Steyl | Leon Prozesky | Wilhelm H. Stoltsz | John A. Lawrence
Four hand-reared, naïve roan antelope, 4 months of age, were exposed to naturally infected pasture on a game farm in Mpumalanga Province, South Africa, where roan are known to die from theileriosis. Various clinical parameters were recorded during this period. The predominant ticks parasitising these animals at the time (January to February), were Rhipicephalus appendiculatus and Rhipicephalus evertsi evertsi adults. After a period of 5 weeks the animals developed signs of clinical theileriosis and were treated with buparvaquone to prevent mortality. Primary hyperplasia of the local draining lymph nodes (Lnn. anorectales) near the feeding site of adult R. evertsi evertsi indicated possible transmission of Theileria sp. (sable) by this tick species. After recovery from theileriosis, these animals were confirmed carriers of Theileria sp. (sable) by PCR (polymerase chain reaction) and DNA probe analysis. Laboratory-bred larvae and nymphs of R. evertsi evertsi and R. appendiculatus respectively, were fed on the ears of these roan antelope. Salivary glands from moulted and prefed adult ticks of each species were dissected and stained for Theileria spp., and the PCR and DNA probe applied to a representative batch of dissected glands. R. appendiculatus adults collected from grass in infected camps were also dissected after prefeeding them on rabbits. Salivary glands of both tick species showed infected acini on staining and were also positive for Theileria sp. (sable) only, on multiprotozoal PCR-screening analysis. There was no statistical significant difference between the infection rate and the intensity of infection between the two tick species. R. appendiculatus ticks collected from grass were also PCR-positive for Theileria sp. (sable).
显示更多 [+] 显示较少 [-]Foot-and-mouth disease virus serotypes detected in Tanzania from 2003 to 2010: Conjectured status and future prospects
2012
Christopher J. Kasanga | Raphael Sallu | Fredrick Kivaria | Mathias Mkama | Joseph Masambu | Mmeta Yongolo | Sachindra Das | Chanasa Mpelumbe-Ngeleja | Philemon N. Wambura | Donald P. King | Mark M. Rweyemamu
This study was conducted to investigate the presence of foot-and-mouth disease virus (FMDV) in different geographic locations of Tanzania. Epithelial tissues and fluids (n = 364) were collected from cattle exhibiting oral and foot vesicular lesions suggestive of FMD and submitted for routine FMD diagnosis. The analysis of these samples collected during the period of 2002 and 2010 was performed by serotype-specific antigen capture ELISA to determine the presence of FMDV. The results of this study indicated that 167 out of 364 (46.1%) of the samples contained FMDV antigen. Of the 167 positive samples, 37 (28.4%) were type O, 7 (4.1%) type A, 45 (21.9%) SAT 1 and 79 (45.6%) SAT 2. Two FMDV serotypes (O and SAT 2) were widely distributed throughout Tanzania whilst SAT 1 and A types were only found in the Eastern zone. Our findings suggest that serotypes A, O, SAT 1 and SAT 2 prevail in Tanzania and are associated with the recent FMD outbreaks. The lack of comprehensive animal movement records and inconsistent vaccination programmes make it difficult to determine the exact source of FMD outbreaks or to trace the transmission of the disease over time. Therefore, further collection and analysis of samples from domestic and wild animals are being undertaken to investigate the genetic and antigenic characteristics of the circulating strains, so that a rational method to control FMD in Tanzania and the neighbouring countries can be recommended.
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