Description and classification of abnormal cercariae of Schistosoma mattheei and a method of concentration and collection.

Over a period of about 12 years, 30 abnormal Schistosoma mattheei cercariae were found among a total of approximately 2.8 million examined. Initially seven were recovered from about 1.02 million (0.0007%), which were examined individually while being counted with the aid of a stereoscopic microscope. Subsequently, on the strength of relatively high percentages of abnormal individuals recovered when counting cercariae that failed to penetrate into oxen, it appeared that the morphologically abnormal cercariae were unable to swim and would mostly sediment out of a suspension while most of the normal cercariae would remain swimming. This surmise is supported by recovery of 23 morphologically abnormal cercariae (0.001%) from about 1.8 million, by examining the sediment after the cercarial suspension had been left standing undisturbed in glass measuring cylinders. The abnormalities ranged from aberrant tails only (e.g. an underdeveloped tail, or different degrees of schism) or aberrant heads only, to abnormalities of both the heads and tails. A suggested schematic classification of abnormal cercariae is presented. A young, adult hamster was exposed to eight S. mattheei cercariae with complete schism of the shaft of the tail, by pipetting the cercariae onto the shaved abdominal skin of the anaesthetised animal. Two underdeveloped females were subsequently encountered in squash preparations of the liver when the hamster was killed for worm recovery 10 weeks after infection, thus showing that some of the abnormal cercariae were viable. A method is also described for killing and fixing cercariae while retaining some of the shining brilliance of live cercariae, without them becoming shrivelled, granular and semi-opaque, as occurs when cercariae die spontaneously or are killed with heat. This is apparently the first report of abnormal cercariae of S. mattheei. In addition, a method of concentrating abnormal cercariae after emergence from a snail, a schematic classification of abnormal cercariae and a method for killing and fixing cercariae while retaining much of the shiny brilliance of live cercariae are also reported for the first time as far as is known.

Little anthelmintic drenching required for lambs finished over winter and spring on annually re-established irrigated pasture on the Highveld of Gauteng Province, South Africa.

As part of a trial to test the profitability of finishing weaner lambs over winter and spring on the Highveld of Gauteng province, an investigation was carried out over 4 consecutive years as to whether or not worm control was necessary while the lambs were on irrigated, improved pastures. Pastures that had not been grazed by sheep or other livestock for at least 5 years were planted to annual ryegrass (Lolium multiflora) that was ploughed under and replanted annually. Weaner lambs were randomly divided into either 2 (A and B) or 3 (A, B and C) groups and finished from April/May to November/December on a separate pasture per group. While Group A lambs were dewormed before being placed on pasture, those in Groups B and C were not. Faecal egg counts were performed at irregular intervals, and when the lambs were sold at the conclusion of each year's trial, the gastrointestinal tracts of 4-5 lambs per trial group were processed for worm recovery. Haemonchus contortus was the dominant worm species, while Trichostrongylus colubriformis, Ostertagia circumcincta and Trichuris spp. were encountered sporadically. From the results obtained it seems unlikely that there is appreciable 'carry-over' of the various worm species from year to year on pastures that are ploughed and replanted annually; thus it is improbable that there will be a build-up of anthelmintic-resistant worms. While on pasture, no drenching was required for the Group A lambs (dewormed before placing on the pasture), nor in 2 of the 4 years in Groups B or B+C that were not drenched and were lightly infected at the start. In the remaining 2 years Groups B or B+C were drenched once only during the course of each trial. Thus, under the conditions as in this study, little worm control is necessary, provided faecal worm egg counts are done to gauge the levels of infection before the lambs are placed on pasture, and to guard against the possibility of an increase in worm burdens thereafter in some years. Also, because of the apparent lack of carry-over between years, anthelmintic treatment at the time of introduction of the lambs or during the period of finishing should be safe as regards progressive selection for anthelmintic resistance. It is also likely to be cost-effective, considering the low cost of anthelmintics in relation to the price of lambs, to counter the possibility of a loss in production if lambs were to harbour relatively heavy worm burdens when introduced.

Schistosoma mattheei--an ovum containing twin miracidia.

A large Schistosoma mettheei ovum containing two miracidia was recovered from a squash preparation of the liver of an experimentally infected hamster. When observed, the miracidia were motile and facing in opposite directions.

Hemangiomatous ameloblastoma: Clinical, radiologic, and pathologic features.

A hemangiomatous ameloblastoma was present in the third molar region of the left mandible of a 26-year-old woman. The histology and radiologic features of this tumor differed from those of a conventional ameloblastoma. Its histologic features were consistent with those of a hemangiomatous ameloblastoma, and its standard radiologic features and computed tomography mimicked that of fibro-osseous lesions, whereas magnetic resonance imaging suggested a vascular lesion. The behavior and prognosis of the hemangiomatous ameloblastoma are uncertain because of the small number of documented cases and lack of long-term follow-up, but are thought to be similar to those of the conventional type. The relevant clinical, radiologic, and pathologic features of this case are presented.

Magnetic resonance imaging in dentistry.

MR imaging has found a place in the imaging sciences. These images are unique in that no ionizing radiation is used, the same tissues may or may not have different appearances with different machine settings, a unique set of terms is used to describe the findings in the images, and these findings can be analyzed with the view of obtaining more diagnostic information not readily available with any other imaging modality. Cases have been presented to help demonstrate differences in T1-weighted and T2-weighted sequences as well as the value of contrast material. Additionally, plain film and CT views were included so that they may be contrasted with the MR images. The role and application of CT versus MR imaging has been further discussed and illustrated by Nortjé and van Rensburg. A typical temporomandibular joint case has also been presented. In the future, it is hoped that clinicians will refer more patients for MR imaging so that diagnoses can be made more accurately with analytic software.

Central calcifying odontogenic cyst. A review of the literature and the role of advanced imaging techniques.

The central calcifying odontogenic cyst (CCOC) is a rare lesion. This paper reports a new case, reviews the clinical, histomorphological and radiographic features reported in the literature and describes the CT and MRI features of this new case. We postulate that, as part of an evolutionary process, cystic COCs originate as unilocular lesions but may later become multilocular. The role of advanced imaging and histology in the diagnostic process are discussed.

Quality control in generic anthelmintics: is it adequate?

We became increasingly concerned about indications of possible substandard efficacy of some generic anthelmintics, particularly after P.C. van Schalkwyk (personal communication, 1990) had found some batches of imported generic products obtained from international brokers to be poorly active, despite apparently normal physical characteristics. Therefore, considering the serious consequences this would have for sheep farming, it was decided to test the efficacy of some of the generic rafoxanide products available on the South African market. One of the three commercial formulations (of highly reputable companies) tested against a known susceptible strain of Haemonchus contortus in sheep was markedly substandard, with an arithmetic mean efficacy of 66.2% (Class B, Reinecke, 1973), compared to Class A efficacy of the other two, which also differed significantly from one another (Mann-Whitney; P = 0.01). Larger differences were found between the three products against a natural infection with a partially resistant strain of H. contortus than against the susceptible strain, with corresponding arithmetic mean efficacies of 28.7% (Class X, or ineffective), 71.3% (Class B) and 87.7% (also Class B). It is concluded that the most likely reason for the observed differences is that international brokers do not disclose the sources of supply of different batches of active ingredient (with the result that the companies buying anthelmintics from them have no way of telling when a source of supply is changed); that the efficacy of such batches differs; and that efficacy testing of individual batches in some cases is inadequate. It is suggested that registering authorities should consider simplified efficacy testing of each new batch of active ingredient before it may be marketed.

Cryopreservation of sheathed third-stage larvae of Oesophagostomum radiatum (nodular worm of cattle).

Sheathed infective larvae of Oesophagostomum radiatum were successfully cryopreserved by the use of a procedure developed for hookworms. The survival rate, as assessed by motility, was 57.9% after 42 d of cryopreservation.

Cryopreservation of third-stage larvae of Strongylus vulgaris (large strongyle of horses).

A technique for the cryopreservation of third-stage larvae of Strongylus vulgaris is described. Infective larvae of S. vulgaris were exsheathed in a 0.16% sodium hypochlorite solution and then transferred into cryotubes containing 0.09% saline. The samples were stored in the gas phase of liquid nitrogen.

Schistosoma mattheei infection in cattle: the course of the intestinal syndrome, and an estimate of the lethal dose of cercariae.

Three groups of young oxen were infected percutaneously with cercariae of Schistosoma mattheei. Three of five oxen infected with 248 cercariae kg-1 mass died or were killed in extremis 58-70 d after infection, a fourth survived extremely severe clinical schistosomosis and the fifth was only slightly affected. None of seven calves infected with 187 cercariae kg-1 died, while one of seven exposed to 119 cercariae kg-1 was in extremis (possibly not from schistosomosis) when killed after 378 d. The LD50 appears to be in the region of the highest dose tested (248 cercariae kg-1), but depends on variations in the viability of the cercariae used. The clinical syndrome was characterized by a drastic, rapid loss in body mass; a severe diarrhoea containing blood clots; straining, gnashing of the teeth, occasional groaning, and other signs of abdominal pain; and markedly sunken eyes. Lethally infected oxen did not become recumbent until shortly before death. Some severely affected animals made remarkable, but slow, recoveries without treatment. Schistosomes, in close association with granulomata, are described-apparently for the first time-in the omental veins of cattle. Mean worm development in three calves that died or were killed in extremis in the acute stage of the disease, was 55.5%. In contrast to most previous findings with S. mattheei, in two of these animals, more female than male worms developed. The worms were recovered by perfusion and, in one animal, a large number of intestinal veins were dissected open to estimate the efficiency of the perfusion method. Only 1.9% of the total worm burden had not been removed by perfusion in this animal.

Case report. Magnetic resonance features of metastatic melanoma of the temporomandibular joint and mandible.

We report a case of histologically verified melanoma of the nose which presented 2 years after initial radiotherapy with left temporomandibular pain, dysfunction and dental sepsis. Conventional radiography revealed a partially dentate mandible with a destructive lesion involving the left condyle, an ill-defined lesion in the right retromolar region and chronic inflammatory apical root lesions. Since MRI of the nose was done at the initial presentation, it was postulated that MRI could be used to characterize the destructive jaw lesions. The MR features were similar to the original nasal lesion and accepted as proof of diagnosis of metastatic melanoma. A literature review reveals only 37 previous cases of metastasis to the temporomandibular joint with none of involvement by melanoma. The role of MRI in the diagnosis of this lesion is also described for the first time.

Desmoplastic ameloblastoma: correlative histopathology, radiology and CT-MR imaging.

A desmoplastic variant of ameloblastoma with osteoplasia in the stroma is reported. This tumour presented in the canine/premolar region of the left maxilla of a 31-year-old woman. It was treated by partial hemimaxillectomy and immediate reconstruction with a non-vascularised iliac graft. The location of this lesion, its histology and radiological features differ from those of the conventional ameloblastoma. The behaviour and prognosis of the desmoplastic ameloblastoma (DA) cannot at this stage be predicted due to the small number of cases that have been reported and a lack of long-term follow-up. To our knowledge this is the first documentation of the CT and MRI features of desmoplastic ameloblastoma with pathologic correlation.

Pneumosinus dilatans of the ethmoid sinus--incidental finding on a cephalometric radiograph.

A case of pneumosinus dilatans of the posterior ethmoidal region is presented. The condition known as pneumosinus dilatans is discussed, as are accessory ethmoidal air cells with respect to their most common localization and radiographic appearance. The diagnostic imaging features of this condition are described and a recommendation of views to adequately delineate this disorder are given. The importance of an adequate and thorough review of the cephalometric radiograph for pathologic conditions is stressed.

Advanced imaging in evaluation of a central mandibular haemangioma.

We present a case of histologically-verified central cavernous haemangioma. The conventional radiological films as well as the computed tomographic (CT) and magnetic resonance imaging (MRI) features of this lesion are described. Plain films showed many of the typical radiological signs of haemangioma, whereas CT was primarily useful for illustrating the bony components of the tumour as well as delineating soft tissue extensions and bony defects not normally visible with plain film examination. MRI proved particularly useful, demonstrating the vascular nature and flow voids representative of feeder vessels and delineating the true extent of the lesion. The literature pertaining to the imaging features of central haemangioma is reviewed and the complementary use of plain films, CT and MRI described. To our knowledge, this is the first report detailing the MRI characteristics of a central mandibular haemangioma.

Fasciola in horses in the Republic of South Africa: a single natural case of Fasciola hepatica and the failure to infest ten horses either with F. hepatica or Fasciola gigantica.

The faeces of 11 horses were examined for Fasciola spp. eggs. One of them was positive for Fasciola hepatica, a finding which was confirmed post-mortem. The 10 negative horses were subsequently infested with either F. hepatica or Fasciola gigantica, each animal receiving orally from 500-9,500 metacercariae. No clinical signs were observed and no fluke eggs were detected in the faeces, and neither immature nor adult Fasciola worms were recovered from the horses slaughtered 16-26 weeks post-infestation with F. hepatica and 28-34 weeks post-infestation with F. gigantica, respectively. The results indicate that horses have a high level of resistance to both South African Fasciola spp. Factors which can probably explain the conflicting reports for the prevalences of fascioliasis in horses throughout the world and the varying results obtained in experimental infestations are briefly considered.

Major skeletal defects in the fetal alcohol syndrome. A case report.

A case of major limb abnormalities due to the fetal alcohol syndrome is described and the similarity to thalidomide-induced embryopathy is noted.

Studies on a naturally occurring R factor harbouring a chromosomal nutritional marker.

A naturally occurring R factor which carried resistance determinants to tetracycline and chloramphenicol as well as a marker for lactose fermentation was found in a strain of Klebsiella pneumoniae isolated from sewage. The TcCmlac+ factor was transferred by conjugation to E. coli K12. It showed no recombination or stable coexistence with R factors of the fi- class. Studies in recombination-deficient (rec-) strains of E. coli K12 showed that the TcCmlac+ factor is an autonomously replicating plasmid. Preparative ultracentrifugation and electron microscopic studies revealed the presence of more than one molecular species. Average contour lengths for two of these species were 11,20 +/- 1,55 mum and 16,14 +/- 1,45 mum, which correspond to molecular weights of about 23,18 X 10(6) and 34,63 X 10(6) daltons, respectively.