Molecular separation of Oesophagostomum stephanostomum and Oesophagostomum bifurcum (Nematoda: Strongyloidea) from non-human primates.

The ITS-2 sequences for adult specimens of Oesophagostomum stephanostomum from the common chimpanzee and Oesophagostomum bifurcum from the Mona monkey were determined. For both species, the length and GC content of the ITS-2 sequences were 216 bp and 43%, respectively. While there was no unequivocal sequence difference among individual worms representing each of the two species, five (2.3%) interspecific nucleotide differences were detected. These differences were associated with the presence of unique restriction sites in the ITS-2 sequence of 0. stephanostomum for multiple endonucleases of diagnostic value for the differentiation of the two taxa by restriction analysis. Pairwise comparisons of the ITS-2 sequences of O. stephanostomum and O. bifurcum with published ITS-2 sequences for five different congeners indicated that these species from the subgenus Conoweberia are closely related, in accordance with previous morphological studies.

Oesophagostomiasis, a common infection of man in northern Togo and Ghana.

Infection with Oesophagostomum sp. is normally considered a rare zoonosis and up to this time its diagnosis has been based on the demonstration of larvae and young adult worms in the typical nodules formed in the intestinal wall. Only in Dapaong, in North Togo, and Bawku, North Ghana, have larger series of clinical cases been described. In the rural areas around these towns, a survey was made in which stool samples were collected and cultured. Third-stage larvae of Oesophagostomum sp. could be found after 5-7 days of incubation at room temperature, and the prevalence of infection with this parasite was often high but varied from one village to another. It was over 30% in seven villages out of the 15 villages surveyed. Anthelmintic treatment resulted in the evacuation of adult males and females of O. bifurcum. It is concluded that O. bifurcum is a locally common parasite of humans, not requiring an animal reservoir for completion of its lifecycle.

'Hydatoxi lualba', an artefact.

Blood samples from controls, pre-eclamptic patients and cord blood from their infants were examined for the so-called Hydatoxi lualba parasite. Using a further modified TBO staining technique on blood-smears made on slides cleaned manually, the 'eggs, larva and worms' could be demonstrated to be successive stages of artefacts originating from threads deposited by the cotton swabs used in manual cleaning. These successive stages of 'worms' could only rarely be found in smears made on industrially cleaned slides.

Preservation of Cowdria ruminantium at low termperatures.

A Nigerian isolate of Cowdria ruminantium was rapidly frozen with or without 10 per cent dimethyl sulphoxide at -85 degrees C and -196 degrees C. All animals inoculated with the frozen stabilates died of heartwater fever.

Preliminary observations on the use of the capillary flocculation test for the diagnosis of heartwater (Cowdria ruminantium infection).

A capillary flocculation test was developed to diagnose heartwater disease of ruminants. Antigen was prepared from the brains of cattle and goats highly infected with Cowdria ruminantium. Sera were obtained from experimentally infected ruminants which either recovered naturally or with the aid of oxytetracycline treatment. Antibodies were first detected one to two weeks after clinical recovery or after treatment, and persisted for periods varying between one and four weeks. Control sera collected from cattle (sheep) and goats in the Netherlands where heartwater does not occur, or from animals serologically positive for Anaplasma marginale or Eperythrozoon ovis infections, did not react to the test.

Morphological variability within Oesophagostomum bifurcum among different primate species from Ghana.

Adult Oesophagostomum bifurcum (Nematoda: Strongylida) from human and non-human primates from Ghana were compared in order to investigate the extent of morphological variability within the species. Using analysis of variance and principal component analysis, significant differences in morphological characters (such as parasite length, width, length of the oesophagus and length of spicules) were demonstrated between O. bifurcum worms from humans, the Mona, Patas or Green monkey and/or Olive baboons. These findings suggest that O. bifurcum from different species of primate host represent distinct population variants, also supported by recent epidemiological and genetic studies of O. bifurcum from such hosts.

Oesophagostomum infections in humans.

Oesophagostomum spp are normally found as nematode parasites of ruminants, pig and monkeys. Occasionally humans are involved. In the past decade it became clear that, in some parts of Africa, humans are adequate final hosts. In those areas, prevalences of infection are high and morbidity is significant. The presence of lumen-dwelling adult worms, which do not seem to cause a great deal of pathology, can be demonstrated through coproculture. The presence of immature worms, encapsulated in nodules and responsible for pathology, on the other hand, is more difficult to confirm. It is not known what factors limit the distribution of endemic human oesophagostomiasis to a small focus in West Africa. The relationship between the 'helminthomas' described a long time ago in Uganda and the human Oesophagostomum infections in West Africa is unclear and it remains a mystery how humans get infected so effectively by ingesting L3 larvae. In this overview, Ton Polderman and Coby Blotkamp give an account of what is known and what is still to be elucidated in human Oesophagostomum infections.

Studies on isolation and drug sensitivity of Trypanosoma vivax in northern Nigeria.

In a study to investigate the occurrence in cattle of Trypanosoma vivax strains resistant to the normal therapeutic dose of homidium, 47 isolates of T. vivax were collected from 10 different trypanosomiasis treatment centres in the North Central State of Nigeria. Of these 47 isolates, 23 produced infection in the experimental animals that were used for subsequent drug sensitivity trials. While all but one of the experimental cattle inoculated with T. vivax became infected, less than 50% of the experimental sheep and none of the experimental goats were able to reproduce infection. This difference in infectivity is discussed and related to the stage of the T. vivax infection in the donor cattle. None of the 23 isolates of T. vivax was resistant to homidium. The value of sheep and goats in T. vivax experiments is discussed.

Differentiation of Entamoeba histolytica and Entamoeba dispar cysts using polymerase chain reaction on DNA isolated from faeces with spin columns.

Since Entamoeba histolytica and Entamoeba dispar were formally recognized as two different species at the World Health Organization (WHO)/Pan American Health Organization (PAHO)/United Nations Educational, Scientific and Cultural Organization (UNESCO) meeting in Mexico City in 1997, the specific differentiation of the two morphologically identical species would seem relevant in clinical diagnosis. Several polymerase chain reaction (PCR)-based methods have been described and used successfully, but methods for DNA isolation from cysts in stool samples are time-consuming and problematic due to inhibitory factors in faeces. The use of the slightly modified QIAamp tissue method (Qiagen, Germany) for DNA isolation was evaluated in 657 unpreserved faecal samples from cases of suspected Entamoeba histolytica/Entamoeba dispar infection. In only 1.7% of the cases was PCR hampered by inhibitors present in the faeces. The DNA isolation procedure was found to be rapid, simple and one that could easily be implemented in a routine diagnostic setting. In 98.8% of Entamoeba histolytica/Entamoeba dispar cyst-positive faecal samples, the true identity of the cysts could be determined using PCR specific for Entamoeba histolytica and Entamoeba dispar, respectively.

Comparison of fresh versus sodium acetate acetic acid formalin preserved stool specimens for diagnosis of intestinal protozoal infections.

The use of sodium acetate acetic acid formalin (SAF)-preserved stool specimens was compared with that of nonpreserved specimens for the recovery of intestinal protozoa. A total of 247 patients, 170 with diarrhea of more than one week's duration and 77 refugees, were asked to collect a stool specimen. Each specimen was placed into two vials, one empty, the other containing SAF fixative. Laboratory investigations included microscopic examination of the concentrated sediment and direct wet smears from both types of stool specimens and the microscopic examination of a permanent stained smear from the unsedimented, SAF-preserved stool specimens. Examination of SAF-preserved stool specimens revealed intestinal protozoa in 149 of the 247 patients. With the conventional procedure using unpreserved stool specimens, intestinal protozoa were found in 89 of the 247 patients. The results show that the examination of SAF-preserved stool specimens, consisting of the microscopic examination of both the concentrated sediment and the permanent stained smear from the unsedimented material, increases the chance of recovering intestinal protozoa as compared to the conventional procedure.

The capacity of the third-stage larvae of Oesophagostomum bifurcum to survive adverse conditions.

Human infections with the intestinal nematode Oesophagostomum bifurcum are commonly found in the Sudan savannah of northern Togo and Ghana. Apparently, the long and hot dry season in this region does not prevent transmission, which is believed to take place through ingestion of the infective, third-stage larvae (L3). Oesophagostomum L3 cultured from human stools, unlike the larvae of Necator americanus, were shown to survive desiccation. In addition, 93% of the O. bifurcum L3 frozen for 24 h at -15 degrees C regained motility when brought back into ambient temperatures. The L3 also survived the acidity of an artificial mixture made to resemble the gastric juices of humans. Desiccated larvae could even be rehydrated in this mixture, indicating the possibility of dust-borne infections. The sturdiness of the L3 is likely to contribute to the high transmission intensity in northern Togo and Ghana.

The in vitro growth pattern of human bone marrow in methylcellulose stimulated by different concentrations of conditioned medium.

The proliferation of human bone marrow in methylcellulose stimulated by various concentrations of conditioned medium (CM) and observed at various intervals was studied. The growth kinetics of granulocytic aggregates was found to differ from monocytic clusters and colonies. Granulocytic aggregates showed a consistent and reproducible dose-response relationship; at day 7, the maximum number of granulocytic aggregates was found at 4% CM. At higher levels, the total number of aggregates decreased, while the number of cells per aggregate increased. The number of macrophage aggregates was far less, depending on the CM concentration. Photographic interval studies showed that at high concentrations of CM, clusters and colonies were formed earlier, but also coalesce to form one colony. Our results suggest that the proliferation kinetics of granulocytic aggregates are complex and preclude simple statements about sensitivity to colony-stimulating activity.

Observations on the morphology of adults and larval stages of Oesophagostomum sp. isolated from man in northern Togo and Ghana.

Infection with Oesophagostomum sp. appears to be extremely common in man in northern Togo and Ghana. Adult specimens were recovered from the intestinal lumen by treatment with pyrantel pamoate and the morphological characteristics of oesophagostomes of man could for the first time be compared with information available on the morphology of oesophagostomes of monkeys. The observations and measurements demonstrated that the species involved is Oesophagostomum bifurcum and that the eggs of this species cannot be differentiated from those of Necator americanus. Both infections occur simultaneously in the population involved. The L1 larvae, too, cannot be differentiated from hookworm L1 larvae. The L3 larvae, however, are characteristic. Diagnoses of human Oesophagostomum infections is based on the detection of these larvae in coprocultures. In the present paper, the eggs, the L1 and L3 larval stages and the adults, are carefully described and photos are given.

Experimental Oesophagostomum bifurcum in monkeys.

OESOPHAGOSTOMUM BIFURCUM: larvae, cultured from human stools collected in northern Ghana, were used to establish experimental infections in monkeys. A patent infection was established in a rhesus monkey (Macaca mulatta) and this infection was used to generate larvae to inoculate additional monkeys. In all, 17 animals were inoculated. Thirteen of 15 animals developed antibodies to the infection between 19 and 62 days post inoculation (PI); two animals had a positive response before inoculation. Four of ten animals developed patent infections between 88 and 134 days and passed eggs in the faeces. Egg shedding was consistent in only one animal, but at low levels of one or two eggs per 2 mg direct smear, and extended over a 400 day period. In the other three animals, egg shedding was sporadic and of only 2-4 weeks duration. In seven animals necropsied between 19 and 22 days PI, one to 17 early fourth-stage larvae were recovered from nodules in the bowel wall; in an eighth animal examined at 314 days, six immature adult worms (early fifth stage) were recovered from nodules in the bowel wall. The morphological features and growth of these recovered larvae are described. Three animals were inoculated with larvae that had been dried for one week at 28 degrees C; two animals began shedding eggs at 128 and 134 days PI, respectively. The present results suggest that the parasite obtained from humans is poorly adapted to lower primate hosts, and supports the concept that Oesophagostomum bifurcum found in humans and monkeys in the same geographical region of northern Ghana and Togo are distinct and that the infections in humans are not likely to represent zoonotic infections acquired from monkeys.

Outbreak of amebiasis in a family in The Netherlands.

Human-to-human transmission of Entamoeba histolytica is rare in industrialized countries. We describe an outbreak of amebiasis in a family in The Netherlands, demonstrating that even with Western standards of hygiene, persistent cyst passage may result in the transmission of E. histolytica to household contacts. If E. histolytica is isolated from a person living in an area of nonendemicity, it may be worthwhile to test all family members for cyst passage.

Polymorphic and monomorphic HLA-DR determinants on human hematopoietic progenitor cells.

The expression of monomorphic Ia-like antigens and polymorphic (allotypic) HLA-DR determinants on CFU-GM, BFU-E, CFU-E, and CFU-GEMM was studied in bone marrow and peripheral blood cells from normal healthy individuals. Using various polyclonal and monoclonal anti-Ia-like antibodies, the presence of HLA-DR backbone antigens was shown on all hematopoietic progenitor cells (HPC) studied, both in complement-dependent cytotoxicity assays and in fluorescence-activated cell sorting (FACS). The expression of allotypic determinants was demonstrated on all HPCs, using the HLA-DR typing sera anti-HLA-DR1, 2, 3, 4, 5, and 7. The Class II antigen MT-2 was also shown on all HPCs, using both monoclonal and alloantisera, whereas the MB-1 (DC-1) determinant could not be demonstrated on HPCs. This might open the possibility of removing MB-1-positive malignant cells from the graft in autologous bone marrow transplantation.