Phylogenetic relationships of human populations in sub-Saharan Africa.

This study utilizes the GM/KM immunoglobulin allotype system to elucidate the phylogenetic relationships of sub-Saharan Africans. The importance of understanding the relatedness of these peoples stems from the sub-Saharan region being the possible birthplace of humans. Haplotype distributions were determined for 19 populations and compared using chi-square analysis. Published data of other sub-Saharan Africans and representative populations worldwide were also added for comparison. Genetic distances between populations were calculated based on haplotype frequencies, and genetic relationships were observed through principal components analysis. Data from the GM/KM system showed a genetic homogeneity of the Bantu populations, with some exceptions, supporting the possibility of a common origin of these peoples. The Malagasy appeared as a divergent population, most likely due to Southeast Asian/Austronesian admixture, as indicated by the presence of the GM*AF B haplotype. The Cape Coloured also showed a divergence, with their genetic structures containing Caucasoid and Khoisan contributions. Finally, the Mbuti Pygmies appeared genetically isolated and had the highest frequency of the GM*A B haplotype out of all studied populations.

Pathology of experimental toxoplasmosis in eastern barred bandicoots in Tasmania.

Wild-caught eastern barred bandicoots (Perameles gunnii) initially seronegative to Toxoplasma gondii, were inoculated orally with approximately 100 T. gondii oocysts. The bandicoots were maintained in indoor pens under laboratory conditions and observed daily. Serial blood samples were tested for agglutinating antibodies to T. gondii. Inoculated bandicoots died 15 and 17 days post infection. A rise in Direct Agglutination Test (DAT) titres was detected at the time of death (1:256, 1:64 respectively). Clinical observations, serological changes, gross findings at necropsy, and histopathological changes were consistent with acute toxoplasmosis. The findings indicate that eastern barred bandicoots are likely to die from primary T. gondii infection, often even before detectable antibodies are produced, reinforcing the significance of toxoplasmosis as a potential contributor to the reduction in numbers of wild populations of eastern barred bandicoots.

Earthworms as paratenic hosts of toxoplasmosis in eastern barred bandicoots in Tasmania.

An experimental feeding study was designed to assess the role of earthworms in the transmission of Toxoplasma gondii infection to eastern barred bandicoots (Perameles gunnii). Six animals with no agglutinating antibodies to T. gondii were fed artificially cultured earthworms that had been maintained in autoclaved nutrient-enriched soil. Two animals were given earthworms that had been maintained in soil contaminated with T. gondii oocysts (P89/VEG strain); two animals were fed on earthworms, which initially had been exposed to soil containing T. gondii oocysts then transferred through three changes of sterile soil; two control bandicoots were fed earthworms maintained in sterile soil. Both bandicoots fed earthworms maintained in T. gondii contaminated soil died 11 and 14 days after feeding. The necropsy findings were consistent with acute toxoplasmosis. Bandicoots fed earthworms exposed to oocysts but then transferred through changes of sterilized soil remained healthy as did control animals. All surviving animals remained seronegative over the 6 wk observation period after feeding. These findings confirm that earthworms, a major component of the natural diet of P. gunnii, can transmit T. gondii infection. It appears that oocysts present in the alimentary tracts of the worms, rather than infective stages of T. gondii in worm somatic tissues, are responsible for these infections.

Epidemiology of giardiasis in Tasmania: a potential risk to residents and visitors.

BACKGROUND: Giardia infection is an ongoing problem in Tasmania and occurs throughout the state. It has been postulated that part of the problem is the reservoir of infection in native animals which is suggested to contribute to infections in humans. To date, however, no detailed study on the epidemiology of giardiasis in Tasmania has been carried out. METHODS: Information regarding the prevalence of Giardia infection in humans and the risk of intrafamilial transmission was obtained from the Department of Community and Health Services and from the direct examination of human or animal fecal samples. RESULTS: Giardia has been found to be present in a wide range of native and domestic animals and in humans of all ages from all over the state. CONCLUSIONS: Giardiasis is endemic in Tasmania and poses a risk to locals as well as to visitors to the state, especially those who participate in wilderness activities such as bushwalking. These people must be aware of the possible risk of Giardia infection and should take precautionary measures to avoid infection.

First record of trypanosomes in Tasmanian bandicoots.

Trypanosomes were observed in 38% of blood smears from southern brown bandicoots (Isoodon obesulus) and in 10% of blood smears from eastern barred bandicoots (Perameles gunnii). This is the first record of such hemoparasites in Tasmanian marsupials. There appeared to be a statistically significant size difference between trypanosomes found in the 2 bandicoot species, suggesting the possibility of 2 distinct species of parasite. There appears to be a distinction between the trypanosomes found in our temperate Isoodon species and the tropical bandicoot. Isoodon macrurus. The use of the microhematocrit method provided an effective means for concentrating trypanosomes, whereas image analysis was a more effective method than the ocular micrometer for obtaining accurate measurements.

Isolation of verotoxigenic Escherichia coli from the Tasmanian environment.

Growing concerns on the emergence of verotoxin producing Escherichia coli (VTEC) in Australia have focused our attention on the possible sources of VTEC within the island state of Tasmania. An analysis of 156 food samples and 194 water samples obtained from various areas revealed evidence of eight possible sources. Six strains, with serotypes Ont:Hnt, O86:H-, O88:H-, O126:H21 and O134:H-, were isolated from water samples. Two VTEC of serotypes Ont:H8, 081:H- were isolated from raw meat samples. The waterborne isolates produced verocytotoxin. VT1, while both foodborne isolates were strong producers of VT2. Three VTEC isolates produced haemolysins, only one produced enterohaemolysin (EntHly) and the remaining were reported with alpha-haemolysin (alpha-Hly) activity. An important feature in the majority of isolates from water was their lack of ability to ferment lactose these isolates are routinely overlooked in public health laboratories.

Giardiasis in native marsupials of Tasmania.

Tasmanian native marsupials were screened for the presence of Giardia spp. over a 3 yr period, revealing a 21% prevalence in the 295 animals tested. A pilot study of experimentally infected eastern barred bandicoots (Perameles gunnii) indicated susceptibility to infection with Giardia duodenalis from a human source.

The first record of a member of the genus Hepatozoon in the eastern barred bandicoot (Perameles gunnii) in Tasmania.

Of 220 wild Eastern Barred Bandicoots (Perameles gunnii) captured in two locations in Tasmania, Australia, 55 (25%) had a detectable parasitaemia with gametocytes of the protozoan genus Hepatozoon in blood films. Blood films were stained with Leishman stain and acridine orange O. Gamonts were commonly found as intracellular forms and occasionally observed as extracellular forms in peripheral erythrocytes. This is the first record of a member of the genus Hepatozoon in any temperate bandicoot and additionally appears to be the first record of this protozoan genus in any native marsupial species of Tasmania.

Bacterial flora of Tasmanian SIDS infants with special reference to pathogenic strains of Escherichia coli.

The general bacterial flora of 38 Tasmanian SIDS infants was examined together with faecal flora of 134 comparison infants ranging in age from birth to 6 months. The microflora of all specimens received was investigated with special emphasis on the toxigenic Escherichia coli (TEC). Samples were examined for verocytotoxigenic E. coli, free faecal verocytotoxin (FVT), heat labile toxin (LT) and heat stable toxin (ST) producers with the use of a Vero cell assay and commercial kits. The findings of this study revealed a high isolation rate (39%) of TEC from SIDS infants as compared to 1.5% from the healthy comparison infants. Atypical E. coli strains were also identified during the study, including E. coli A-D. An analysis of the same specimens for rotaviral and adenoviral antigens indicated that 30% of the SIDS cases were positive as compared to 20% in the comparison group.

The clinical significance of Escherichia coli Alkalescens-Dispar in Tasmania.

An investigation in 1989 of human fecal specimens revealed that of 111 diarrheal samples examined Escherichia coli Alkalescens-Dispar (A-D) were found in 9 (8.1%), but none were isolated from normal stool samples. Further studies have shown that although these isolates may be potential pathogens, they seem to remain unrecognized by routine laboratories due to their biochemical similarity to shigellae, a problem further exacerbated by their extensive sharing of O antigens. All the isolates were screened with an invasive DNA probe and all but three isolates were found to have a common plasmid. They were also confirmed to be invasive in HEp-2 monolayers. No isolates were shown to produce heat-labile or heat-stable toxin but electronmicroscopy revealed the presence of pili. The A-D isolates were biotyped using the two-tier schema of Crichton and Old and were categorized into biotypes 11, 12 and 16. These data confirm the importance of introducing an awareness of this intermediate strain into routine laboratories.

An investigation of culture media for the isolation of shigellae.

In this study we have investigated the efficiency of presently available culture media for the isolation of shigellae. XLD was found to be the medium of choice, combined with both less and more selective culture media (e.g. MacConkey, and Hektoen or DCA). By using these media in combination it was found that not only were shigellae isolated more often and efficiently, but fewer problems were encountered in isolating other Enterobacteriaceae.

Chronic strongyloidiasis in Tasmanian veterans--clinical diagnosis by the use of a screening index.

Chronic infection with Strongyloides stercoralis presents a diagnostic problem because of the low recovery of the organism from stools and the insensitivity of current serological tests. Of 150 former Far East POWs, 26 (17%) had S. stercoralis in stools. The clinical features in 18 stool-positive patients were compared to those in 24 stool-negative patients and showed that strongyloidiasis was associated with a higher frequency of alteration in bowel habit, upper abdominal discomfort, rash and eosinophilia. On the basis of these features, a screening index was devised which largely separated stool-positive and stool-negative patients and led to helpful therapy in three of four patients with compatible symptoms who lacked a definitive diagnosis. Treatment with thiabendazole appeared to be superior to treatment with mebendazole.

Further studies on head lice and their control in Tasmania.

This study on the control of head lice infestation in Tasmania confirms the efficacy of malathion preparations compared with lindane preparations.

Childhood central nervous system cysticercosis in Australia.

Cysticercosis of the central nervous system is seen infrequently in Australia. Most cases occur in adults, but two imported cases of neurocysticercosis in children are described. A 10-year-old Anglo-Indian girl presented with aseptic meningitis, raised intracranial pressure and a block to the flow of cerebrospinal fluid in the lumbar region. Laminectomy showed two cysticerci in the spinal subdural space. A three-year-old boy from Zimbabwe suffered a focal seizure. A granuloma that contained a degenerate cysticercus was found in the left parietal cortex. Serological examination of blood for cysticercosis was performed only in the second case and gave negative results. Examination of stools in both children gave negative results for the presence of parasites, cysts and ova.