Freshwater nematodes from South Africa. 8. New and known species of Actinolaimoidea

Afractinolaimus Andrássy, 1970 is regarded as valid, its diagnosis slightly emended, and the following species transferred to it: Paractlnolaimus capensis, P. minor, P. zairensis and P. magaliesmontanus. The name of the type species thus becomes A. magaliesmontanus, since it has priority and is regarded as conspecific with A. noblei, the designated type. Additional biometrical data and distribution records are presented for A. magaliesmontanus. A. zairensis is reported from South Africa. Information is given for several populations of P. microdentatus. Two new species of Neoactinolaimus are described: N. brachydorus n. sp. is characterized by an exceptionally short and stout odontostyle, and N. barbieri n. sp. is distinguished from the closely related N. vaalensis by a thicker cuticle, more prominently set-off head, corrugated vestibule, longer oesophagus and several other minor morphological differences. Egtitus Thorne, 1967 is regarded as valid, and the following combination proposed: Egtitus zealandicus (Clark, 1963) n. comb, (synonym: Actinolaimus zealandicus).     

Three new Chromadoropsis species (Nematoda,Desmodoridae) from Southern Africa and the North Sea

Three new Chromadoropsis species with four pharyngeal bulbi are described from Southern Africa, Namibia (S.W.A.) and the North Sea. C. granulosus sp.nov. is described from a sandy beach near Port Elizabeth. This species is characterized by a very distinct layer of yellow granules just below the cuticle. C. namibiensis sp.nov. is described from a sandy beach at Langstrand, Namibia. This species can be distinguished by the length and shape of the gubernaculum and spicules as well as the size of the capitulum. C. longispiculosa sp.nov. is described from the North Sea and is characterized by the long spicules and the presence of numerous porids. The genus Chromadoropsis Filipjev, 1918 is revised.     

Neothada hades N.sp. from South Africa,with notes on the genus and a key to the species (Nematoda: Tylenchidae)

Neothada hades n.sp. from South Africa is characterized by the posession of small but distinct stylet knobs, 149-175 body annules intersected by 14 longitudinal lines (incisures), protruding lateral fields marked by four incisures, and an elongate-conoid tail with bluntly rounded tip. Reasons are given why N. canceilata (Thorne 1941) and N. tatra (Thome & Malek 1968) are regarded as two distinct species, and why N. canceilata apud Andrassy, 1982 is regarded as distinct from Thome’s species. Andrassy’s species is renamed N. andrassyi n.sp. A key is presented for the six recognized species of Neothada.     

Validation of an ELISA method for the serological diagnosis of canine brucellosis due to Brucella canis

In the present study, the validation of an enzyme-linked immunosorbent assay (ELISA) for serodiagnosis of canine brucellosis is described. Two different antigenic extracts, obtained by heat or ultrasonic homogenization of microbial antigens from a wild isolate of Brucella canis bacteria, were compared by ELISA and Western blot (WB). A total of 145 canine sera were used to define sensitivity, specificity and accuracy of the ELISA as follows: (1) sera from 34 animals with natural B. canis infection, confirmed by blood culture and PCR, as well as 51 sera samples from healthy dogs with negative results by the agar–gel immunodiffusion (AGID) test for canine brucellosis, were used as the control panel for B. canis infection; and (2) to scrutinize the possibility of cross reactions with other common dog infections in the same geographical area in Brazil, 60 sera samples from dogs harboring known infections by Leptospira sp., Ehrlichia canis, canine distemper virus (CDV), Neospora caninum, Babesia canis and Leishmania chagasi (10 in each group) were included in the study. The ELISA using heat soluble bacterial extract (HE-antigen) as antigen showed the best values of sensitivity (91.18%), specificity (100%) and accuracy (96.47%). In the WB analyses, the HE-antigen showed no cross-reactivity with sera from dogs with different infections, while the B. canis sonicate had various protein bands identified by those sera. The performance of the ELISA standardized with the heat soluble B. canis antigen indicates that this assay can be used as a reliable and practical method to confirm infection by this microorganism, as well as a tool for seroepidemiological studies.     

Polystomatidae (Monogenea) of southern African Anura: Polystoma channingi n.sp. parasitic in two closely related Cacosternum species

Polystoma channingi is described as a new species of polystomatid flatworm (Monogenea) parasitic in the urinary bladder of Cacosternum nanum in the Eastern Cape Province, South Africa. In a locality where C. nanum and C. boettgeri occur sympatrically the parasite has been found in both species. This finding of a Polystoma sp. in two closely related host species questions the strict host-specificity generally ascribed to the genus, but supports the hypothesis that host-specificity is determined by the oncomiracidium's ability to recognize the tadpole as a suitable host. This is the first polystome to be described from the genus Cacosternum and the ninth species of Polystoma from South Africa. The species is distinguished by its huge haptor and suckers relative to the body size. The haptor length/body length ratio of 0.38 is by far the largest for the known southern African polystomes. The prevalence of infection with P. channingi n.sp. was 25% for C. nanum and 40% for C. boettgeri, while the mean intensity of infections in adult frogs was 1.5 for C. boettgeri and 1.0 for C. nanum.     

Marine benthos near the Saldanha Bay iron-ore loading terminal

Trianthema hereroensis is one of the few plant species which persist during long dry periods in the Namib dunes. Direct and indirect utilization of this plant by Namib faunae, for food and shelter, were observed. Utilization of T. hereroensis by Oryx gazella resulted in vigorous regrowth which was preferentially utilized. The extent of utilization as well as the response of this plant to utilization, are discussed.     

Congenital stationary night blindness is associated with the leopard complex in the Miniature Horse

Objective To determine if congenital stationary night blindness (CSNB) exists in the miniature horse in association with leopard complex spotting patterns (LP), and to investigate if CSNB in the miniature horse is associated with three single nucleotide polymorphisms (SNPs) in the region of TRPM1 that are highly associated with CSNB and LP in Appaloosas. Animals studied Three groups of miniature horses were studied based on coat patterns suggestive of LP/LP (n = 3), LP/lp (n = 4), and lp/lp genotype (n = 4). Procedures Horses were categorized based on phenotype as well as pedigree analysis as LP/LP, LP/lp, and lp/lp. Neurophthalmic examination, slit‐lamp biomicroscopy, indirect ophthalmoscopy, and scotopic flash electroretinography were performed on all horses. Hair samples were processed for DNA analysis. Three SNPs identified and associated with LP and CSNB in the Appaloosa were investigated for association with LP and CSNB in these Miniature horses. Results All horses in the LP/LP group were affected by CSNB, while none in the LP/lp or lp/lp groups were affected. All three SNPs were completely associated with LP genotype (χ² = 22, P << 0.0005) and CSNB status (χ² = 11, P < 0.0005). Conclusions The Miniature Horse breed is affected by CSNB and it appears to be associated with LP as in the Appaloosa breed. The SNPs tested could be used as a DNA test for CSNB until the causative mutation is determined.     

Theileria orientalis: a review

Theileria orientalis (also known historically as T. sergenti and T. buffeli) is responsible for benign or non-transforming theileriosis, and exerts its major effect through erythrocyte destruction. The life cycle of T. orientalis is essentially similar to that of other Theileria species, except that the schizonts do not induce transformation and fatal lymphoproliferation. The pathogenesis of anaemia as a result of infection is not clearly established and may be multifaceted. Clinical signs of weakness, reluctance to walk and abortion are early but non-specific indications of disease, particularly if accompanied by a history of cattle being moved. Physical examination may reveal pallor (pale eyes, vaginal mucosa), pyrexia, and elevated heart and respiratory rates. T. orientalis is an economically important parasite of cattle in New Zealand, Australia and Japan, especially where naïve animals are introduced into an endemic area or in animals under stress. Increased awareness of the risks posed by the parasite is required to enable management practices to be implemented to minimise its impact.     

Successful surgical management of eosinophilic granuloma on the urethral process of a gelding associated with Habronema spp. infection

Habronemiasis, otherwise known as summer sores, is a parasitic disease of horses, donkeys and other equids, commonly encountered in subtropical and tropical regions. It occurs as a result of nematode infestation of the skin and typically manifests as ulcerative granulating lesions or masses. Habronema muscae, Habronema microstoma and Draschia megastoma are the usual invaders, usually transmitted by house flies, face flies and stable flies. In this case report, an eosinophilic granuloma on the urethral process of a 15-year-old gelding is presented, followed by successful surgical excision without further medical treatment. To the authors’ knowledge, equine eosinophilic granuloma on the urethral process associated with habronemiasis has not previously been documented in southern Europe and should be considered as a potential differential diagnosis for penile masses.     

Turritella declivis Adams & Reeve,in Reeve, 1849 (Mollusca: Gastropoda) – a South African not an Australian species,and a characteristic component of the Agulhas Bank benthos

The name Turritella declivis, as described by Adams and Reeve in the ‘The Zoology of the Voyage of HMS Samarang’ (Adams & Reeve 1848-1850), is currently used for two distinct species of turritellid gastropod, one inhabiting the Agulhas Bank off South Africa and the other occurring off the Australian coast. Examination of the type material clearly shows that the name is referable to the southern African species. The Australian species must henceforth be known as Turritella captiva Hedley, 1987, a name previously regarded as a junior synonym of T. declivis. The original type locality ‘China Seas’ is erroneous, as was often the case with material collected during the voyage of the Samarang. It is emended to be the Agulhas Bank, over much of which T. declivis is common and may, in places, be hugely abundant, forming Turritella-dominated benthic communities. Such communities have been recorded in other parts of the world and are frequently associated with seasonal upwelling events, but have not previously been documented off South Africa.     

Mechanisms underlying detection of seed dormancy by a scatter‐hoarding rodent

The mechanism underlying detection of seed dormancy by scatter‐hoarding rodents is unclear, although previous work suggests that the pericarp plays an important role in signaling dormancy status. Eastern gray squirrels (Sciurus carolinensis) consume early germinating seeds as they are more likely to perish immediately, whereas dormant seeds tend to be cached. To examine the mechanisms underlying dormancy detection, we characterized physical and chemical differences between germinating and dormant pericarps of northern red oak (Quercus rubra), American chestnut (Castanea dentata) and the BC3 hybrid of Chinese chestnut and American chestnut (Castanea mollissima × C. dentata) using scanning electron microscopy and gas chromatography‐ mass spectrometry. We found that, as seeds break dormancy, the wax layer on the pericarp degrades and is accompanied by the escape of lower molecular weight kernel compounds or lipid metabolism byproducts. Our field experiments showed that squirrels were 4–8 times more likely to consume seeds that were altered to remove pericarp wax coating or that were sprayed with seed chemicals. We argue that dormancy detection by scatter‐hoarding rodents is a complex process involving physical cues such as loss of pericarp wax and chemical cues such as emission of olfactory cues.     

Chronic non-progressive pneumonia of sheep in New Zealand – a review of the role of Mycoplasma ovipneumoniae

Chronic non-progressive pneumonia (CNP) is a common disease which affects lambs in New Zealand during late summer and autumn. Mycoplasma ovipneumoniae can be recovered from a high proportion of lesions but it is also present in some normal lungs. Bacteria, especially Pasteurella haemolytica, can also be recovered from more than half the lungs of affected animals.

Isolates of M. ovipneumoniae are genetically heterogeneous, as demonstrated by examination of their DNA or total cellular proteins, and are serologically heterogeneous as shown by metabolic inhibition tests. The number of strains present in New Zealand is large and several distinguishable strains can be recovered from each affected lung. Mycoplasma ovipneumoniae has pathogenic potential as indicated by its ability to produce hydrogen peroxide, cause ciliostasis and by its possession of a capsule.

Chronic non-progressive pneumonia can be transmitted consistently to over 50% of lambs by inoculation of pooled pneumonic lung homogenate and transmission can be suppressed by broad spectrum antibiotics. In contrast, penicillin does not prevent the development of lesions but diminishes their severity. Pooled lung homogenate treated with digitonin, which inactivates mycoplasmas, has failed to transmit CNP. Pure cultures of M. ovipneumoniae produce only mild lesions in some animals, whereas inoculation with pooled lung homogenate (from which no viruses were isolated) containing mixed strains of M. ovipneumoniae and free from bacteria, is more effective in producing lesions.

Research work to date suggests that CNP may be initiated by colonisation of the lung by M. ovipneumoniae which causes ciliostasis and elicits an exudate allowing colonisation of the lungs by bacteria especially P. haemolytica and by other strains of M. ovipneumoniae. The immune response to the initial strain of M. ovipneumoniae may inhibit its replication but would be less effective in inhibiting heterologous strains of the organism allowing their sequential replication. Eventually production of a broad immune response to M. ovipneumoniae would lead to its elimination which in turn would facilitate the elimination of other microorganisms and the resolution of lesions. As natural immunity to CNP occurs within the first year, it may be possible to develop an effective and useful vaccine. Such a vaccine may need to include multiple strains of M. ovipneumoniae.     

Cytopathic effects of Tritrichomonas foetus on bovine oviduct cells

Tritrichomonas foetus is an extracellular parasite of the reproductive tract in cattle. To investigate the cytopathic effects of T. foetus in deeper parts of the reproductive tract, a bovine primary oviduct epithelial cell system (BOECs) was developed. Reproductive tracts were obtained from cows and the effect of co-incubating T. foetus with BOECs was analyzed by scanning electron, transmission electron and fluorescence microscopy. Viability tests were performed using colorimetric methods, TUNEL (Terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling), fluorescein diacetate, propidium iodide, JC-1 and annexin-V. The results demonstrate that: (1) the in vitro oviduct epithelium is useful for interaction experiments with T. foetus; (2) T. foetus adheres to the BOECs as single separate cells, and later on the cells aggregate as large clusters; (3) the posterior region of the cell initiates the process of adhesion and forms filopodia and digitopodia; (4) T. foetus severely damages BOECs leaving imprints in the epithelial cells, wide intercellular spaces, and large lesions in the epithelium; and (5) T. foetus provokes bovine oviduct cell death by apoptosis and secondary necrosis. Our observations indicate the possibility that T. foetus can move through the reproductive tract to the oviduct and that infertility in cows can be mediated by an attack on the oviduct cells by T. foetus.     

Evaluation of a Western Blot and ELISA for the detection of anti-Trichinella-IgG in pig sera

Human trichinellosis is a foodborne disease caused by ingestion of infective Trichinella muscle larvae via pork or meat of other food animals which are susceptible to this zoonotic parasite. There are new approaches for a risk-oriented meat inspection for Trichinella in pigs which are accompanied by monitoring programmes on herd level to control freedom from this parasite. For this purpose, testing schemes utilizing serological tests with a high sensitivity and specificity are required.This study aimed at the evaluation of an ELISA and a Western Blot (WB) for the detection of anti-Trichinella-IgG in terms of sensitivity and specificity taking results of artificial digestion as gold standard. For this purpose, 144 field sera from pigs confirmed as Trichinella-free as well as 159 sera from pigs experimentally infected with T. spiralis (123), T. britovi (19) or T. pseudospiralis (17) were examined by ELISA (excretory–secretory antigen) and WB (crude worm extract). Sera from pigs experimentally infected with four other nematode species were included to investigate the cross-reactivity of the antigen used in the WB. For all Trichinella-positive pig sera, band pattern profiles were identified in the WB and results were analysed in relation to ELISA OD% values.Testing of pig sera revealed a sensitivity of 96.8% for the ELISA and 98.1% for the WB whereas the methods showed a specificity of 97.9 and 100%, respectively. WB analysis of Trichinella-positive pig sera revealed five specific band patterns of 43, 47, 61, 66, and 102 kDa of which the 43 kDa protein was identified as the predominant antigen. The frequency of the band pattern profile was irrespective of the dose and the period of infection as well as the Trichinella species investigated.In conclusion, monitoring in swine farms for Trichinella antibodies should be based on screening pig sera by means of ELISA followed by confirmatory testing through WB analysis.     

Pneumonia of pigs: a review

Pneumonia of pigs is one of the more important disease factors limiting pig production. Of the varieties of pneumonia affecting this species enzootic pneumonia caused by Mycoplasma spp. is the most common and most important. The major effects of this disease are lowered food conversion ratio and poor weight gain. Deaths are usually the result of secondary infection by necrotising, pus-forming bacteria. Eradication of the disease is expensive and requires depopulation and restocking. Control and treatment by antimicrobial agents is most effective if the drug combination used takes regard of the bacteria complicating the disease on any particular property. Other forms of pneumonia such as those caused by Haemophilus pleuropneumoniae, Salmonella cholerae-suis and Aujeszky’s disease virus can be important on individual farms. The role of other agents such as Bordetella bronchiseptica and adenoviruses in respiratory disease of pigs remain to be clarified.     

Diagnostic assessment without cut-offs: Application of serology for the modelling of bovine digital dermatitis infection

Bovine digital dermatitis (BDD) is an epidermitis which is a leading cause of infectious lameness. The only recognized diagnostic test is foot inspection, which is a labour-intensive procedure. There is no universally recognized, standardized lesion scoring system. As small lesions are easily missed, foot inspection has limited diagnostic sensitivity. Furthermore, interpretation is subjective, and prone to observer bias. Serology is more convenient to carry out and is potentially a more sensitive indicator of infection. By carrying out 20 serological assays using lesion-associated Treponema spp. isolates, three serogroups were identified. The reliability of the tests was established by assessing the level of agreement and the concordance correlation coefficient. Subsequently, an ELISA suitable for routine use was developed.The benchmark of diagnostic test validation is conventionally the determination of the key test parameters, sensitivity and specificity. This requires the imposition of a cut-off point. For serological assays with outcomes on a continuous scale, the degree by which the test result differs from this cut-off is disregarded. Bayesian statistical methodology has been developed which enables the assay result also to be interpreted on a continuous scale, thereby optimizing the information inherent in the test. Using a cross-sectional study dataset carried out on 8 representative dairy farms in the UK, the probability of infection, P(I), of each individual animal was estimated in the absence of a ‘Gold Standard’ by modelling I as a latent variable which was determined by lesion status, L as well as serology, S. Covariate data (foot hygiene score and age) were utilized to estimate P(L) when no lesion inspection was performed. Informative prior distributions were elicited where possible. The model was utilized for predictive inference, by computing estimates of P(I) and P(L) independently of the data.A more detailed and informative analysis of the farm-level distribution of infection could thus be performed. Also, biases associated with the subjective interpretation of lesion status were minimized. Model outputs showed that young stock were unlikely to be infected, whereas cows tended to have high or low probabilities of being infected. Estimates of probability of infection were considerably higher for animals with lesions than for those without. Associations were identified between both covariates and probability of infection in cows, but not in the young stock. Under the condition that the model assumptions are valid for the larger population, the results of this work can be generalized by predictive inference.     

Assessing the effectiveness of intubation as a challenge model in contagious bovine pleuropneumonia vaccine experiments

A study was carried out to assess the effectiveness of a bronchoscope in administering a pathogenic field strain of Mycoplasma mycoides subsp. mycoides (MmmSC) in cattle challenge experiments. Out of 16 animals inoculated using the bronchoscope, 10 (62.2%) showed clinical disease as evidenced by fever and 15 (93.8%) displayed typical lesions of CBPP from which MmmSC was isolated. Serum samples collected weekly were tested by Complement Fixation Test (CFT) and competitive enzyme-linked immunosorbent assay (c-ELISA). Antibodies to MmmSC were detected in 10 out of the 16 animals by the CFT and 11 out of the 16 animals by c-ELISA. The onset of clinical disease was as early as 2 days post-inoculation, and most of the animals developed clinical disease 2 to 3 weeks post-infection. These results clearly demonstrate that nasotracheal inoculation of pathogenic strain of MmmSC with the aid of a bronchoscope can lead to early onset of clinical disease; similar to previous studies but with higher numbers of animals showing clinical disease. This is in contrast with previous studies where early clinical disease was observed in as little as 15% of inoculated animals. This nasotracheal inoculation method using a bronchoscope can, therefore, be adopted for use in experimental challenge infections of cattle. This method is found to be a better replacement to the contact transmission method whose drawback includes extra cost of donor animals and unpredictable rate and timing of transmission from intubated to challenge animals.     

Sarcocystid organisms found in bile from a dog with acute hepatitis: a case report and review of intestinal and hepatobiliary Sarcocystidae infections in dogs and cats

Sarcocystidae is a family of coccidian protozoa from the phylum Apicomplexa that includes Toxoplasma, Neospora, Sarcocystis, Hammondia, and Besnoitia spp. All species undergo a 2‐host sexual and asexual cycle. In the definitive host, replication is enteroepithelial, and infection is typically asymptomatic or less commonly causes mild diarrhea. Clinical disease is most frequently observed in the intermediate host, often as an aberrant infection, and is mostly associated with neurologic, muscular, or hepatic inflammation. Here, we review the literature regarding intestinal Sarcocystidae infections in dogs and cats, with emphasis on the life cycle stages and the available diagnostic assays and their limitations. We also report the diagnostic findings for an 11‐year‐old dog with acute neutrophilic hepatitis, biliary protozoa, and negative biliary culture. Although Toxoplasma and Neospora IgG titers were both high, PCR for these 2 organisms was negative for bile. The organisms were identified by 18S rDNA PCR as most consistent with Hammondia, either H heydorni or H triffittae. This is the first report of presumed Hammondia organisms being found in canine bile.     

Preliminary molecular analysis of Clostridium difficile isolates from healthy horses in northern Italy

Clostridium difficile, associated with a wide spectrum of diseases in humans, as well as in several animal species, is an important cause of colitis in adult horses and foals. The aim of this study was to investigate by toxin gene profile and PCR-ribotyping the molecular characteristics of 14 C. difficile strains isolated from 42 faeces of healthy horses. Both toxin genes, tcdA and tcdB, were present in only 1 isolate (7.1%). Six isolates (42.9%) demonstrated tcdA−/tcdB+ genotype, and seven isolates (50.0%) were tcdA−/tcdB−. All strains were binary toxin genes negative (cdtA−/cdtB−). The PCR-positive strains, except for the tcdA+/tcdB+ isolate, tested negative for, in vitro, A and/or B toxins production by EIA. Eleven distinct ribotypes were observed.In conclusion, C. difficile can be present in the normal intestinal flora of healthy adult horses, in addition to foals. These animals could therefore play an important role as potential reservoirs of toxigenic strains.