Determinants of the geographical distribution of endemic giardiasis in Ontario, Canada: a spatial modelling approach

Giardiasis surveillance data as well as drinking water, socioeconomic and land-use data were used in spatial regression models to investigate determinants of the geographic distribution of endemic giardiasis in southern Ontario. Higher giardiasis rates were observed in areas using surface water [rate ratio (RR) 2.36, 95 % CI 1.38-4.05] and in rural areas (RR 1.79, 95 % CI 1.32-2.37). Lower rates were observed in areas using filtered water (RR 0.55, 95 % CI 0.42-0.94) and in those with high median income (RR 0.62, 95 % CI 0.42-0.92). Chlorination of drinking water, cattle density and intensity of manure application on farmland were not significant determinants. The study shows that waterborne transmission plays an important role in giardiasis distribution in southern Ontario and that well-collected routine surveillance data could be useful for investigation of disease determinants and identification of high-risk communities. This information is useful in guiding decisions on control strategies.

Risk factors for Salmonella typhimurium DT104 and non-DT104 infection: a Canadian multi-provincial case-control study

To identify risk factors for sporadic Salmonella Typhimurium definitive phage-type 104 (DT104) and non-DT104 diarrhoeal illness in Canada, we conducted a matched case-control study between 1999 and 2000. Cases were matched 1:1 on age and province of residence. Multivariate analysis suggested that recent antibiotic use [odds ratio (OR) 5.2, 95% confidence interval (CI) 1.8-15.3], living on a livestock farm (OR 4.9, 95% CI 1.9-18.9), and recent travel outside Canada (OR 4.1, 95% CI 1.2-13.8) are independent risk factors for DT104 illness. Similar analyses suggested that recent travel outside North America is a sizable risk factor for non-DT104 illness (OR 66.8, 95% CI 6.7-665.3). No food exposure was a risk factor in either analysis. Educating health-care providers and the public about appropriate antibiotic use and antimicrobial resistance is important. Appropriate administration of antibiotics to livestock, particularly cattle, and hygienic measures such as handwashing after contact with farm animals may reduce risk. Travel represents an important and probably underestimated risk factor for sporadic illness with S. Typhimurium. Improved national surveillance and detailed investigation of travel-related illness are required.

A squamous cell carcinoma and an adenocarcinoma in Australian treefrogs

We describe the pathology in a captive adult White lipped treefrog (Litoria infrafrenata) with a squamous cell carcinoma of the skin and a free-living adult Common green treefrog (L. caerulea) with an adenocarcinoma of the skin. Although many amphibian neoplasms have been reported world wide, none had been described in Australian species.

New allele frequency database: http://www.allelefrequencies.net

A new website (http://www.allelefrequencies.net) has been compiled to execute the frequency of alleles at various polymorphic regions of different populations in the field of histocompatibility and immunogenetics. Data for HLA alleles has been added but this will be extended to include frequency data of polymorphisms in other immunogenetic regions, e.g. cytokines, KIR receptors, MIC.

Distribution of HLA-A alleles in eight ethnic groups from Pakistan

The extreme polymorphism found at some loci of the HLA system has made it an invaluable tool for population genetic analyses. In this study eight diverse ethnic groups from Pakistan were analyzed at the HLA-A locus using sequence specific primers for polymerase chain reaction (PCR-SSP) and then further typed to the allele level using a two-stage sequence specific oligonucleotide probe (SSOP) strategy. Four of these ethnic groups (Burusho, Hazara, Kalash, Pathan) were from the north and four (Baloch, Brahui, Sindhi and Parsi) were from the south of Pakistan. Nine alleles were identified as unique to a particular ethnic group within Pakistan. Maximum variation was seen in the HLA-A*02 allele family for which 11 alleles were detected in the eight Pakistani ethnic groups. The alleles that showed significant variation between the Pakistani ethnic groups include A*0101, A*0206, A*0209, A*0207, A*0217, A*1101, A*2402/09 N/11 N, A*2902, A*3301 and A*3001. A phylogenetic tree based on DA distances for HLA-A allele frequencies separated the Pakistani populations from other world populations and also separated the only Dravidian speaking population of Pakistan, the Brahui, from the remaining Indo-European speaking ethnic groups of Pakistan.

Are human platelet alloantigens (HPA) minor transplantation antigens in clinical bone marrow transplantation?

The role of human platelet alloantigens (HPA) in clinical bone marrow allotransplantation was investigated. The leading hypothesis was that HPA alloepitopes act as minor histocompatibility antigens and aggravate graft-versus-host disease (GVHD). To exclude the effect of MHC disparity, only HLA identical donor-recipient pairs were entered into the study. The influence of HPA compatibility on overall survival, occurrence of relapses and haematopoietic recovery was also investigated. A total of 223 patients who received a graft from an HLA-identical sibling, genotyped for HPA -1, -2, -3, -4 and -5, were observed over a post-transplant period of 24 months following the protocol recommended by EBMT. The data from patients having received grafts from HPA compatible donors were compared to data from patients having received grafts that were mismatched in HPA allotypes in the GVH direction. Analysis of the incidence of acute and chronic (GVHD), overall survival, relapse incidence, haematopoietic recovery and some other clinical parameters did not reveal any significant difference between the HPA-matched and -mismatched groups of patients, regardless of their age. Our results give no evidence that HPA-1, -2, -3 and -5 alloantigens should be considered minor transplantation antigens in clinical bone marrow transplantation.

The IL12B 3' untranslated region DNA polymorphism is not associated with early-onset type 1 diabetes

A recent study employing Australian and UK type 1 diabetes families has demonstrated significant transmission bias to affected offspring of a polymorphism (1188A allele; termed allele 1) in the 3' untranslated region (3'UTR) of the interleukin 12B (IL12B) gene which encodes the IL-12p40 subunit of the pro-inflammatory cytokine IL-12. However, results from replication studies in other populations have been controversial. We performed both case-control (n=120 cases; n=330 controls) and family-based (n=307 families) association studies, using the transmission disequilibrium test, to investigate if allele 1 is associated with early-onset type 1 diabetes in Northern Ireland. No association was observed between allele 1 and type 1 diabetes in either case-control (80.8% vs 80.8%; P=0.98) or family-based (49.7% transmissions; P=0.94) studies. Our results do not support earlier reports of an association between allele 1 in the 3'UTR of the IL12B gene and type 1 diabetes.

Pathogenesis studies with Australian bat lyssavirus in grey-headed flying foxes (Pteropus poliocephalus)

OBJECTIVE

To examine the susceptibility of the grey-headed flying fox (Pteropus poliocephalus) to Australian bat lyssavirus (ABL), and to provide preliminary observations on the pathogenesis of the disease in flying foxes.

PROCEDURE

Ten flying foxes were inoculated intramuscularly with ABL, and four with a bat-associated rabies virus. Inoculated animals were observed daily, and clinical samples collected every 9 to 14 days. Animals with abnormal clinical signs were euthanased, and samples collected for histological, serological, virological and immunohistological examinations. At 3 months post inoculation (PI), all survivors were euthanased, and each submitted to a similar examination.

RESULTS

Three ABL-inoculated flying foxes, and two rabies-inoculated animals developed abnormal clinical signs between 15 and 24 days PI. All three ABL-inoculated animals had histological lesions consistent with a lyssavirus infection, and lyssaviral antigen was identified in the central nervous system (CNS) of each. Virus was isolated from the brain of two affected animals. Of the rabies-inoculated flying foxes, both had histological lesions and viral antigen in the CNS. Virus was recovered from the brain of only one. None of the five affected flying foxes developed anti-lyssavirus antibodies, but, by 3 months PI, five of the seven ABL-inoculated survivors, and one of the two rabies virus-inoculated survivors, had seroconverted. The dynamics of the immune responses were quite variable.

CONCLUSIONS

The response of flying foxes to ABL, administered by a peripheral route of inoculation, was similar to that of bats inoculated peripherally with bat-derived rabies viruses.

A common KIR2DS4 deletion variant in the human that predicts a soluble KIR molecule analogous to the KIR1D molecule observed in the rhesus monkey

A KIR2DS4 deletion variant allele, previously identified through KIR PCR-SSOP typing studies, was characterized, alongside a normal KIR2DS4 allele, by cDNA cloning and sequencing and its prevalence in the population determined using a deletion specific probe. The KIR2DS4 deletion variant was found in 72 of the 90 individuals screened and differed from the normal KIR2DS4 sequence by a single 22 bp deletion in exon 5. The deletion causes a frameshift predicting a truncated KIR2DS4 protein with a significantly altered D2 domain that would be secreted due to the loss of the transmembrane/cytoplasmic domains. Parallels with a recent study in the rhesus monkey highlighting access to the same open reading frame as the deletion variant, also predicting a soluble KIR molecule, are drawn.

Distribution of HLA alleles in Portugal and Cabo Verde. Relationships with the slave trade route

HLA-A, -B, and -DR frequencies were analysed in populations from Portugal and the Madeira and Cabo Verde Archipelagos, aiming to characterize their genetic composition. Portuguese settlers colonized both Archipelagos in the 15th and 16th centuries. Madeira received many sub-Saharan slaves to work in the sugar plantations, and Cabo Verde served as a pivotal market in the Atlantic slave trade and was populated by individuals coming from the Senegambia region of the West African coast. The population of Madeira shows the highest genetic diversity and the presence of alleles and haplotypes usually linked to sub-Saharan populations, the haplotypes accounting for 3.5% of the total. Cabo Verde presents typical markers acknowledged to be of European or Ibero-Mediterranean origin, thus revealing the admixture of European settlers with Sub-Saharan slaves. Altogether the number of European haplotypes reaches 15% of the total. The Portuguese population shows a perceivable and significant heterogeneity both in allele and haplotype frequencies, unveiling a differential input of peoples from different origins. A PCA of the populations studied, plus other relevant ones, clearly shows gene heterogeneity in mainland Portugal as well as the differences and relationships between these populations and Madeira and Cabo Verde.

First identification of a ranavirus from green pythons (Chondropython viridis)

Ten juvenile green pythons (Chondropython viridis) died or were euthanized shortly after having been illegally imported into Australia from Indonesia in 1998. Histologic examination of two of the three snakes that died revealed moderately severe chronic ulceration of the nasal mucosa and focal or periacinar degeneration and necrosis of the liver. In addition there was severe necrotizing inflammation of the pharyngeal submucosa accompanied by numerous macrophages, heterophils, and edema. An iridovirus was isolated in culture from several tissues and characterized by immunohistochemistry, electron microscopy, enzyme-linked immunosorbent Assay, polyacrylamide gel electrophoresis, polymerase chain reaction and sequence analysis, restriction endonuclease digestion, and DNA hybridization. This is the first report of a systemic ranavirus infection in any species of snake and is a new member of the genus, Ranavirus.

A descriptive analysis of giardiasis cases reported in Ontario, 1990-1998

Cases of giardiasis in Ontario were described using notifiable disease data from the Ontario Ministry of Health for the years 1990-1998 inclusive. The mean annual age- and sex-adjusted incidence rate was 25.77 cases per 100,000 population for the 25,289 cases reported. Children under five years of age had the highest incidence of disease. Males had a higher mean annual incidence in all age groups. Four deaths occurred among cases. The most frequently reported symptoms were loose stools or watery diarrhea (50.1%). A seasonal pattern was noted, peaking in late summer and early autumn. The most frequently reported probable risk settings were the home (40.1%) and travel (39.1%). The study findings suggest that a high proportion of cases occur in urban areas and spatial analysis showed the highest incidence around Lake Huron and Georgian Bay. Unfiltered water and person-to-person contact are believed to be important sources of infection.

One thousand renal transplants at Belfast City Hospital: post-graft neoplasia 1968-1999, comparing azathioprine only with cyclosporin-based regimes in a single centre

From 1968-1999, 868 recipients of 1,000 renal transplants were followed up for neoplasia. Altogether, 102 tumours were diagnosed in 94 patients (11.8% incidence). Eighty-seven occurred among 750 single and 15 occurred among 118 multiple graft recipients. Three of 11 patients with pre-existing tumour developed posttransplant neoplasia, either new or recurrent. The most frequently seen posttransplant neoplasms were squamous carcinoma of skin, basal cell carcinoma (BCC), posttransplant lymphoproliferative disease (PTLD) and gastro-intestinal (GI) cancer. Forty-one tumour-related deaths occurred (44% mortality). Patients on CSA (C) regimes had a greater cumulative incidence of tumour after transplantation than those on azathioprine and low-dose prednisolone alone (A regime) had--12.7% (34 of 268) vs. 4.5% (15 of 335) of those at risk up to 5 years (relative increased rate of incidence 2.4) with more early cases of PTLD. C-regime patients who developed neoplasia had been prescribed significantly higher CSA doses than tumour-free controls (4.5 vs. 3.4 mg/kg/day; p = 0.014). Patients who made a late conversion from the A to the C regime subsequently developed more neoplasms than nonconverted controls (25.7% vs. 12%), mainly due to early and often aggressive squamous carcinoma. Transplant survival figures were similar for both A- and C-regime groups. These findings suggest that current CSA doses are higher than are necessary for optimal graft survival and thus increase the risk of early neoplasia without any compensatory advantage. A dose reduction of CSA to less than 3.5 mg/kg/day in long-surviving, stable graft recipients should reduce tumour risk without imperilling function. Late conversion from the A to the C regime should be avoided where possible and CSA doses in this situation kept to a minimum.

Mitochondrial DNA polymorphism: its role in longevity of the Irish population

The mtDNA genome has been implicated as playing a pivotal role in determining the longevity and success of the human lifespan. A PCR-RFLP methodology was used to identify polymorphic restriction enzyme sites within a 2643 bp region of the mtDNA genome and a table of genetic haplotypes for a healthy aged and a younger control cohort of patients was constructed. Forty-six different mtDNA haplotypes and 11 groups of related haplotypes were identified across the two age groups but statistical analysis failed to show any significant associations. The European J haplogroup, previously reported to be associated with longevity, was not found at an increased frequency within the Irish aged population (P=0.36). However, the haplotypes comprising the J haplogroup could be differentiated into two distinct branches by the presence or absence of the two polymorphic restriction sites, 16,389g and 16,000g. The branch of haplotypes defined by 16,389g displayed a significant increased frequency in the aged samples (8%) compared to the controls (1%), P=0.015. Inversely, the branch of haplotypes defined by 16,000g displayed a significant decreased frequency in the aged samples (4%) compared to the controls (13%), P=0.011. The polymorphism (mt5178A) associated with longevity in the Japanese was not found in the Irish population, while the polymorphism (mt9055A) associated with successful ageing in the French centenarians was found at an increased frequency in the Irish aged population (9%) compared to the younger control group (5%), but failed to reach a level of statistical significance, P=0.164.