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SUMMARYToxocara canisand T. catiare highly prevalent nematode infections of the intestines of dogs and cats. In paratenic hosts, larvae do not mature in the intestine but instead migrate through the somatic tissues and organs of the body. The presence of these migrating larvae can contribute to pathology. Toxocaralarvae can invade the brains of humans, and while case descriptions of cerebral toxocariasis are historically rare, improved diagnosis and greater awareness have contributed to increased detection. Despite this, cerebral or neurological toxocariasis (NT) remains a poorly understood phenomenon. Furthermore, our understanding of cognitive deficits due to toxocariasis in human populations remains particularly deficient. Recent data describe an enhanced expression of biomarkers associated with brain injury, such as GFAP, AßPP, transforming growth factor ß1 (TGF-ß1), NF-L, S100B, tTG, and p-tau, in mice receiving even low doses of Toxocaraova. Finally, this review outlines a hypothesis to explore the relationship between the presence of T. canislarvae in the brain and the progression of Alzheimer's disease (AD) due to enhanced AD-associated neurodegenerative biomarker expression.

Toxocara canis, the parasitic roundworm of dogs, can infect a number of paratenic hosts, such as mice and humans, due to the widespread dissemination of its ova in the environment. In these paratenic hosts, larvae have been shown to exhibit a predilection for the central nervous system, resulting in an increasing number of parasites migrating to the brain as infection progresses. In an initial experiment, we investigated the differential brain involvement of T. canis in 7 strains of inbred mice, and chose 2 strains, susceptible (BALB/c) and resistant (NIH) to cerebral infection. In a second experiment, both strains were investigated in terms of course of migration, larval accumulation, and behavioural response to T. canis infection. Results revealed that infected BALB/c mice took significantly longer to drink from a water source (following a period of deprivation), compared with control mice, indicating some degree of memory impairment. Cerebral larval recoveries from both strains of mice demonstrated variation between the two experiments, suggesting that larval burdens may not be a reliable indicator of susceptibility or resistance to T. canis infection. The percentage of total recovered larvae in each organ may be a better representation of larval distribution. Our model system may provide insights into the impact of chronic geohelminth infection on cognitive development.

Ascaris suum and Ascaris lumbricoides exhibit an over-dispersed frequency distribution in their host populations in both the adult and larval stages. The impact of host factors on this observed distribution is still poorly understood and difficult to investigate in the natural host populations. The use of a mouse model has been supported by the observations that the larval migratory pattern, in this host, mimics the pattern observed in the pig. We explored the extrinsic factors that might affect the quantitative recovery of larvae during this migration in order to standardize a model system facilitating accurate future assessment of host genetic variation on this phase of the infection. In Exp. 1 larvae accumulated in the livers of both C57BL/6j and BALB/c mice up to and including days 4–5 p.i. and then declined in both strains until day 9. Loss of larvae from the livers corresponded to arrival in the lungs and maximum accumulation on day 7 p.i. but recovery was considerably higher in C57BL/6j mice. It was concluded that day 7 recoveries gave the best indication of relative resistance/susceptibility to this parasite. In Exp. 2 A/J, BALB/c, CBA/Ca, C57BL/6j, C3H/HeN, DBA/2, NIH, SJL, and SWR mice were compared. C57BL/6j mice were identified as the most susceptible strain and CBA/Ca mice as having the most contrasting phenotype, but with a similar kinetic pattern of migration. Finally, in Exp. 3, a strong positive correlation between the size of the inoculum and the mean worm recovery from the lungs was found in CBA/Ca and C57BL/6j mice, but the difference between these strains was highly consistent, 66·6–80%, regardless of the initial dose. These results demonstrate that, using our protocols for infection and recovery, between-experiment variation in A. suum worm burdens is minimal, and that C57BL/6j mice are highly susceptible to infection compared to other strains. The mechanistic basis of this susceptibility in relation to the resistance of other strains is unknown, but the possibilities are reviewed.

To estimate the test-retest reliability of a modified version of the Self-assessed Physical Activity Checklist two administrations separated by 5 days were conducted for 52 boys and 51 girls in Grade 6 in Australia. Intraclass correlation coefficients were calculated to assess the reliability. Similar test-retest reliabilities were found between boys and girls for light, moderate, and total physical activity, with the largest difference for vigorous physical activity (.44 vs .12). The results suggest that the checklist is a more appropriate measure of boys' physical and sedentary activity as boys reported higher reliability coefficients on all categories except for light physical activity and TV/Video watching.

A hypothesis has been erected stating that in the British Isles the acanthocephalan, Pomphorhynchus laevis can be separated into 3 strains, an English, Irish and marine strain. Ecological and morphological evidence exists in support of this hypothesis. An investigation at the molecular level was conducted in order to test the validity of the existing evidence. A mitochondrial gene, subunit I of cytochrome c oxidase was partially sequenced from 3 Irish populations of P. laevis, 1 Scottish population and 3 English populations. P. laevis sequences from brown trout from Ireland, England and Scotland were very similar, showing a mean sequence divergence of 0·7%. Sequences from two populations of P. laevis from English chub and bullhead were also similar to each other (0·35% divergence). These two groups of sequences, the brown trout group and the chub/bullhead group were 2·2% different. These data confirm the existence of at least 2 strains in Ireland and Britain, although there is evidence to suggest that these strains are defined by their host species rather than by their geographical distributions.

Universal leukoreduction of blood components is becoming the standard of care. Flow cytometry methods are being used for quality control of the leukoreduction process. We provide an atlas of atypical flow cytograms generated by a commercial LeucoCOUNT™ assay that was used to enumerate residual leukocytes in leukoreduced red blood cell components. Numeric results are derived from a flow cytogram generated by the assay. Three types of atypical flow cytogram patterns were observed during process validation or routine quality control of leukoreduced red blood cell components. (a) Fixation artifact: Fixation of control or test samples can alter the staining intensity compared with fresh cells. (b) “Rain” pattern: Flow cytometry methods count slightly damaged leukocytes not removed during leukoreduction. Slightly damaged leukocytes appear on a flow cytogram like “rain” falling from a well-defined “cloud” of intact residual leukocytes. Discrepancies between automated flow cytometry results and subjective manual counting methods can occur. (c) Autofluorescence-debris pattern: Cell debris and age-related changes in the sample can cause shifts in the fluorescence staining pattern, resulting in erroneous test results. Review of flow cytograms is essential for accurate reporting of flow cytometry–based methods for enumerating residual leukocytes in leukoreduced blood components. Cytometry (Clin. Cytometry) 50:254–260, 2002. © 2002 Wiley-Liss, Inc.

The aim of the present study was to compare the helminth infra and component communities of wild and stocked brown trout in Lough Feeagh, in the west of Ireland, and also to examine the establishment and development of helminth communities in stocked brown trout. Fish were sampled in May, August and November 1997 and 1998 and an additional sample of wild brown trout was examined in April 1997. In total 217 wild trout and 122 stocked trout were examined. The acanthocephalans Acanthocephalus clavula and Pomphorhynchus laevis were the first parasite species to infect stocked trout in May 1997. In May 1998 both acanthocephalan species along with the trout specialists Eubothrium crassum and Crepidostomum farionis were the first to infect trout. Mean species richness values for stocked trout increased from May to November, in 1997 and 1998. For wild trout, mean species richness values increased from April to November, in 1997 and decreased from May to November in 1998. The parasite communities of wild trout were richer than those of stocked trout in May of both years. In August the parasite communities recorded for wild and stocked trout were similar in terms of the number of species present but differed in terms of structure, and in November the parasite communities of stocked trout were richer than those of wild trout.

ABSTRACTWe genotyped 418 sera from volunteer blood donors from two large, regional blood centers in the United States who were HBsAg positive by an enzyme-linked immunosorbent assay (ELISA). The HBV genotypes were determined by a serological method using a preS2 epitope ELISA kit (Institute of Immunology, Tokyo, Japan) with monoclonal antibodies. Of the 418 samples, the genotypes of 320 could be determined (76.6%). One hundred forty-three (34.2%) were genotyped as A (preS2 subtype su), 31 (7.4%) were genotyped as B (subtype m), 59 (14.1%) were genotyped as C (subtype ks), 83 (19.9%) were genotyped as D or E (subtype ksu), and 4 (1.0%) were genotyped as F (subtype k). This kit cannot differentiate genotypes D and E. For 98 (23.4%) of the 418 samples, the genotype could not be determined; 11 of these 98 samples were positive for at least one of the preS2 genotype-specific epitopes (m, k, s, and u), but the combinations of positive epitopes were different from those of samples that could be genotyped; 45 had only the common epitope (b). In the group with a high signal-to-cutoff (S/C) ratio, the HBV genotype could be determined for 199 (84%) of 237 samples; in contrast, in the low-S/C-ratio group, only 10 (20%) of 51 samples could be genotyped (P< 0.001). These findings may indicate the limitation of genotyping samples with low S/C ratios for HBsAg by ELISA or the existence of genotype G or other new HBV genotypes in HBsAg-positive blood donors in the United States. Of the genotyped samples, 201 were assayed for HBeAg; only 9 (4.5%) were positive for HBeAg. The frequency of genotype C in HBeAg-positive donor samples (5 of 9 or 56%) was higher than that in HBeAg-negative donor samples (33 of 192, or 17%) (P= 0.022).

Recently, blood centers began investigational testing for HIV RNA by pooled nucleic acid testing (NAT). A 35-year-old frequent platelet donor tested HIV p24 antigen positive, antibody negative before implementation of NAT. He made 2 platelet donations (day -4 and -11) immediately before testing positive for HIV. The donor's HIV seroconversion was monitored, and stored samples were tested retrospectively for HIV RNA. Platelet recipients were tested for HIV infection. The day -4 sample tested positive for HIV RNA by pooled and individual sample NAT. The day -11 sample tested negative for HIV RNA by both NAT tests. The 2 recipients of the day -4 platelets tested HIV RNA and p24 antigen positive. The recipient of the day -11 platelets could not be tested because he had died. HIV NAT would have prevented transmission of HIV had it been available at the time of this donor's HIV seroconversion.

Recent reports from Europe have advocated the use of bacterial culturing of platelets on Day 2 or 3 of storage to extend the shelf life of platelets to 7 days, thereby reducing the outdating of platelets and preserving a limited medical resource. To assess the optimal timing, the necessary sensitivity, and the possible efficacy of bacterial detection, the bacterial growth characteristics were reviewed in 165 platelet units, each inoculated on the day of collection with one of the following organisms: Bacillus cereus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Serratia marcescens, Staphylococcus aureus, and Staphylococcus epidermidis from four previously published studies. Quantitative culture data from inoculated platelet concentrates from five sites and four studies were combined into one database and analyzed for bacterial concentration thresholds (≥101, ≥102, ≥103, ≥104, ≥105 CFU/mL) by day of storage. All examples of B. cereus, P. aeruginosa, K. pneumoniae, S. marcescens, and S. aureus had concentrations ≥102 CFU per mL by Day 3 after inoculation. By Day 4, all units with these organisms contained ≥105 CFU per mL. Units contaminated with S. epidermidis showed slower and more varied growth. By Day 3 after inoculation, 81.3 percent had 102 CFU per mL. By Day 4 after inoculation, 46 (95.8%) of 48 units had concentrations ≥102 CFU per mL. These experiments suggest that an assay capable of detecting 102 CFU per mL on Day 3 of storage would detect the vast majority of bacterially contaminated platelet units, prevent many cases of platelet-associated bacterial sepsis, and provide a scientific basis for the extension of the current platelet storage time. It would be expected that a rare, slow-growing organism could escape such a detection scheme.

Testing has improved the safety of the blood supply. We have excellent serologic tests in place now and are implementing nucleic acid based tests to identify asymptomatic carriers of viruses during the infectious part of the pre‐seroconversion (window) period. However, the blood supply was already quite safe after a variety of other mechanisms had been put into place besides testing to screen out individuals at risk of carrying the most important transfusion transmissible agents. An important safety factor is the use of volunteer, unpaid (unremunerated) blood donors. The best alternative to implementing yet more tests to reduce, but not eliminate, the minute residual risks of transfusion transmission of such agents as HIV, HBV and HCV is the application of microbial inactivation technology to blood and blood components. Such microbially inactivated, cellular blood components should not have the risk of transmitting infectious agents, but may have other, different risks, since nothing has yet been shown to be one hundred percent safe (i.e., risk free). The use of a test to detect carriers of spongiform encephalopathies to prevent their theoretical transmission by transfusion may cause harm to donors and might increase risk for recipients by decreasing the available blood supply.

Children putatively immune to the large roundworm Ascaris lumbricoides were identified in an area of Nigeria where infection is hyperendemic. Immunity was associated with higher levels of serum ferritin, C-reactive protein, and eosinophil cationic protein, indicating ongoing acute phase or inflammatory processes. In contrast, children who were susceptible to the infection had little serological evidence of inflammation despite their high parasite burdens. Immunoglobulin G (IgG) antibody activity in all subclasses was present in high titer in most children but appeared to have no protective function. Despite exceptionally high total IgE levels, there was no evidence that atopic responses to local common allergens was associated with natural immunity to Ascaris. Among those individuals who produced IgG antibody to recombinant ABA-1 allergen of Ascaris, the naturally immune group had significantly more IgE antibody to the allergen than did those susceptible to the infection. IgE antibody responses in conjunction with innate inflammatory processes therefore appear to associate with natural immunity to ascariasis.

The incidence of transfusion‐associated hepatitis in the United States has fallen dramatically since the late 1960s. Where once the risks were so great that as many as one in three transfused patients contracted hepatitis, now they are infinitesimal. Many factors share responsibility for this accomplishment; however, two stand above the rest: (i) improved donor selection and screening criteria, especially elimination of paid blood donations; and (ii) major advances in testing for viral hepatitis carriers. Currently, four tests are used for the prevention of transfusion‐associated hepatitis: (i) hepatitis B surface antigen; (ii) hepatitis C virus antibody; (iii) hepatitis B core antibody; and (iv) alanine aminotransferase. The first two tests are largely responsible for the current low risks of transfusion‐associated hepatitis due to hepatitis B virus and hepatitis C virus of 1 in 63000 and 1 in 125000, per unit, respectively. To further reduce the risks of transfusion‐associated hepatitis will require the enhanced sensitivity provided by nucleic acid amplification techniques (e.g. polymerase chain reaction). Currently, however, no such tests are licensed and practical, automated, or inexpensive enough for individual blood donor screening. We have made such great strides in the prevention of transfusion‐transmitted hepatitis that background rates of viral hepatitis now greatly exceed the risk of transmission via transfusion. For this reason, while it may still be reasonable to consider a transfusion as a possible cause for hepatitis, it is imperative that many other possibilities (e.g., iatrogenic and other risk factors) be ruled out.

We recently reported detection of a transient increase in circulating donor leukocytes (WBCs) in immunocompetent recipients 3 to 5 days posttransfusion (tx) (Blood85:1207, 1995). We have now characterized survival kinetics of specific donor WBC subsets in additional tx populations. Eight female elective surgery patients (pts) were sampled pre-tx and on days 1, 3, 5, 7, and 14 post-tx. Ten female trauma pts transfused with a total of 4 to 18 U of relatively fresh red blood cells were sampled up to 1.5 years post-tx. WBC subsets from frozen whole blood were isolated using CD4, CD8 (T cell), CD15 (myeloid), and CD19 (B cell) antibody-coated magnetic beads. Donor WBCs were counted by quantitative polymerase chain reaction (PCR) of male-specific sex determining region (SRY) sequences. PCR HLA typing and mixed leukocyte reaction (MLR) between recipient and donor WBCs were performed on two of the trauma tx recipients who had long-term chimerism of donor cells post-tx. In 6 of 8 female surgery pts, circulating CD4+male donor cells peaked at day 3 or 5 (0.01 to 1 cell/μL), followed by clearance by day 14. In 7 of 10 female trauma pts, we observed multilineage persistence of male donor WBCs (CD4, CD8, CD15, CD19) for 6 months to 1.5 years post-tx at concentrations of 10 to 100 cells/μL. In 2 trauma recipients studied, MLR showed no, or very low, response to WBC of the single donor implicated as the source of microchimerism by HLA typing. Establishment of long-term multilineage chimerism in trauma recipients is probably caused by engraftment of donor stem cells and mutual tolerance between recipient and donor leukocytes. A better understanding of factors determining clearance versus chimerism of transfused leukocytes is critical to prevention of alloimmunization and transfusion-induced graft-versus-host disease, and, potentially, to induction of tolerance for transplantation.

ABSTRACTChildren putatively immune to the large roundworm Ascaris lumbricoideswere identified in an area of Nigeria where infection is hyperendemic. Immunity was associated with higher levels of serum ferritin, C-reactive protein, and eosinophil cationic protein, indicating ongoing acute phase or inflammatory processes. In contrast, children who were susceptible to the infection had little serological evidence of inflammation despite their high parasite burdens. Immunoglobulin G (IgG) antibody activity in all subclasses was present in high titer in most children but appeared to have no protective function. Despite exceptionally high total IgE levels, there was no evidence that atopic responses to local common allergens was associated with natural immunity to Ascaris. Among those individuals who produced IgG antibody to recombinant ABA-1 allergen ofAscaris, the naturally immune group had significantly more IgE antibody to the allergen than did those susceptible to the infection. IgE antibody responses in conjunction with innate inflammatory processes therefore appear to associate with natural immunity to ascariasis.

Ausria was shown to be considerably more sensitive than CEP by comparing titers of HBAg + sera and by testing selected proficiency panels, sera from hepatitis patients, and sera from experimentally infected rhesus monkeys; CEP+, Ausria– sera were never encountered. However, in testing NIH donors and personnel, 19 of 20 Ausria+, CEP– sera were shown by neutralization studies to be nonspecific for HBAg, i.e., false positives. Nonspecificity was confirmed by an alternate radioimmunoassay procedure and, in one serum, by density-gradiant ultracentrifugation. Testing of 35 additional Ausria +, CEP– sera from New Jersey donors showed 13 specific and 22 (63%) non-specific reactions. It is mandatory that serum from every Ausria+, CEP– donor undergo specificity testing. In addition to the 14 specific Ausria +, CEP– sera, two sera, subsequently shown to be CEP+, were undetected on the initial CEP test (one was transfused and resulted in hepatitis). These sera were strongly positive by Ausria; sera subject to reader error in CEP are unequivocally positive by Ausria. Ausria tests on CEP– donors suspected of transmitting HBAg failed to implicate a donor in each of eight cases. Some HBAg+ hepatitis will continue to occur despite universal application of Ausria or other tests of equal sensitivity.

To assess the relationship of donor alanine aminotransferase (ALT) level to recipient hepatitis, 283 transfused patients were prospectively followed up after open heart surgery; hepatitis developed in 12.7%, of which 97% was non-A, non-B. The ALT tests on 3,359 donors to these patients indicated that risk of hepatitis was significantly associated with the level of donor ALT; 29% of 52 patients receiving at least 1 unit of blood with an ALT level greater than 53 IU/L had hepatitis develop (20.7 cases per 1,000 units), compared with 9% of 231 recipients of only blood with an ALT level of 53 IU/L or less (7.8 cases per 1,000 units). Calculation of corrected efficacy predicts that, at an exclusion level equivalent to 2.25 SDs above the mean log for normal subjects, ALT testing of donors could prevent 29% of posttransfusion hepatitis at the loss of 1.6% of donor units.(JAMA 1981;246:630-634)