Kua-Eyre Su

Seroepidemiology of Toxocara canis infection among mountain aboriginal schoolchildren living in contaminated districts in eastern Taiwan

We conducted a seroepidemiological study of Toxocara canis infection among mountain aboriginal schoolchildren aged 7–12 years living in contaminated districts in eastern Taiwan. To detect sera IgG (≥1:64) we used a T. canis larval excretory‐secretory antigen‐based enzyme‐linked immunosorbent assay. A short questionnaire elicited information on the practices of raising dogs, playing with soil, eating raw vegetables, or whether the child normally washed his/her hands before eating. The overall seroprevalence was quite high, reaching 76.6% (252/329). Neither age nor gender seemed to be important factors related to a positive serology. Aboriginal schoolchildren who raised dogs (OR = 1.83, 95% CI: 1.04–3.19, P = 0.03), or played with soil (OR = 2.52, 95% CI: 1.49–4.25, P < 0.001) seemed to be more susceptible to T. canis infection than those who did not. Children who habitually washed their hands before eating (OR = 0.57, 95% CI: 0.33–0.97, P = 0.04) had a lower chance of acquiring T. canis infection than those who did not.

Blood–brain barrier impairment with enhanced SP, NK‐1R, GFAP and Claudin‐5 expressions in experimental cerebral toxocariasis

Infection by Toxocara canis in humans may cause cerebral toxocariasis (CT). Appreciable numbers of T. canis larvae cross the blood–brain barrier (BBB) to invade the brain thus causing CT. In the present studies, we evaluated the BBB permeability and BBB injury as assessed by the cerebral Evans blue (EB) concentration as well as by pathological changes and glial fibrillary acidic protein (GFAP) expression in T. canis‐infected mice monitored from 3 days (dpi) to 8 weeks post‐infection (wpi). The vasodilation neuropeptides, the expressions of substance P (SP) and its preferred binding neurokinin‐1 receptor (NK‐1R) as well as claudin‐5 of tight‐junction proteins associated with BBB impairment were also assessed by Western blotting and reverse‐transcriptase polymerase chain reaction. Results revealed that BBB permeability increased as evidenced by a significantly elevated EB concentration in brains of infected mice. BBB injury appeared due to enhanced GFAP protein and mRNA expressions from 4 to 8 wpi. Leukocytes might have been unrelated to BBB impairment because there was no inflammatory cell infiltration despite T. canis larvae having invaded the brain; whereas markedly elevated SP protein and NK‐1R mRNA expressions concomitant with enhanced claudin‐5 expression seemed to be associated with persistent BBB impairment in this experimental CT model.

Prevalence of Intestinal Infection due to Cryptosporidium Species Among Taiwanese Patients with Human Immunodeficiency Virus Infection

BACKGROUND/PURPOSE Cryptosporidiosis causes significant morbidity and mortality in human immunodeficiency virus (HIV)-infected patients who do not receive highly active antiretroviral therapy. Related data on cryptosporidiosis in Taiwanese HIV-infected patients are very limited. This study assessed the prevalence of intestinal infection due to Cryptosporidium spp. among Taiwanese patients with HIV infection. METHODS This retrospective review included 1044 patients with HIV infection treated between June 1994 and June 2004. Intestinal colonization due to Cryptosporidium spp. was identified by polymerase chain reaction and restriction fragment length polymorphism of stool specimens collected from 332 of the HIV-infected patients without gastrointestinal symptoms, 90% of whom were receiving highly active antiretroviral therapy. RESULTS Five out of 1044 (0.5%) HIV-infected patients had a diagnosis of intestinal cryptosporidiosis by endoscopic biopsy or examinations of stool specimens. Intestinal colonization due to Cryptosporidium spp. was found in four of 332 (1.2%) asymptomatic HIV-infected patients between 2001 and 2003; two were due to C. hominis, and one each were due to C. felis and C. meleagridis. CONCLUSION Our findings indicate that the prevalence of intestinal colonization due to Cryptosporidium is low among HIV-infected patients in Taiwan.

Combined Treatment with Interleukin-12 and Mebendazole Lessens the Severity of Experimental Eosinophilic Meningitis Caused by Angiostrongylus cantonensis in ICR Mice

ABSTRACT Angiostrongylus cantonensis is the major cause of eosinophilic meningoencephalitis cases in Taiwan. Mice were orally infected with 35 infective larvae. One group of mice were given a single dose of mebendazole (20 mg/kg of body weight) per os at various times and examined at 14 days postinfection (dpi) for worm recovery rate and pathological studies. A 94 to 97% reduction in worm recovery was observed when medication was given at 4 to 5 dpi. Sections of the brains revealed that untreated infected mice developed typical severe eosinophilic meningoencephalitis. Meninges of these mice were thickened by massive infiltration of eosinophils, whereas only moderate pathological change was observed in the brains of mice that were treated with mebendazole at 4 dpi. Infected mice that received daily injections of 10 ng of interleukin-12 (IL-12) only for various numbers of days also exhibited moderate pathological changes in the brain. Eosinophil infiltration in the brains of these mice was low, and severe mechanical injuries in the parenchyma were observed. Treatment with mebendazole in combination with IL-12, however, resulted in low levels of worm recovery and dramatic lessening of the eosinophilic meningitis. A reverse transcriptase PCR assay of mRNA expression in the brain also revealed that the use of IL-12 had shifted the immune response of the mouse from Th2 type to Th1 type. This study could be used in developing strategies for the treatment of human angiostrongylosis.

Sero-epidemiology of Toxocara canis infection among aboriginal schoolchildren in the mountainous areas of north–eastern Taiwan

Abstract A sero-epidemiological study of Toxocara canis infection was conducted among Atayal schoolchildren (aged 7–12 years) residing in the mountainous areas of north–eastern Taiwan. The 73 children investigated were each checked for anti-Toxocara IgG, in ELISA based on the larval excretory–secretory antigens of T. canis larvae. A short, self-administered questionnaire was then used to collect relevant information from each subject, including data on the keeping of dogs, playing in soil, eating raw vegetables, and whether the subjects normally washed their hands before eating. Once the seropositive children had been identified, odds ratios (OR), with their corresponding 95% confidence intervals (CI) and P-values, were calculated for each potential risk factor. When diluted 1:64, sera from 42 (57.5%) of the children gave a positive result in the ELISA, indicating that these 42 children were seropositive for T. canis infection. Seropositivity did not appear to be associated with the age or gender of the subject, the eating of raw vegetables, or the regular failure to wash hands prior to a meal. Compared with the other subjects, however, those who admitted living in a household where dogs were kept (OR = 3.79; CI = 1.23–11.69; P=0.02) or playing in soil (OR = 3.00; CI = 1.10–8.16; P=0.03) appeared at increased risk of seropositivity.

Seroepidemiology of Toxoplasma gondii Infection Among Chinese Aboriginal and Han People Residing in Mountainous Areas of Northern Thailand

A seroepidemiological survey of Toxoplasma gondii infection among Chinese refugees, including Akka and Yau aborigines and Han people living in mountainous areas at elevations of 1,100–1,400 m in Chiang-Rai Province of northern Thailand, was conducted during January 2003 using the latex agglutination test. The overall seroprevalence of T. gondii infection was 9.1% for Akka aborigines, 37.9% for Yau aborigines, and 7.9% for Han people, respectively. No significant gender difference in seroprevalence was found among any of the groups (P > 0.05). The results of a multiple logistic regression analysis for Yau aborigines and Han people showed that the older the age, the higher the odds ratios (OR) of being seropositive (OR = 3.0, 95% confidence interval [CI] = 0.5 to 16.9, P < 0.001 and OR = 1.5, 95% CI = 0.3 to 8.0, P = 0.06 for the elderly group vs. the child group for the Yau aborigines and Han people, respectively). In contrast, the OR was lower among older Akka aboriginal populations (OR = 0.1, 95% CI = 0.0 to 0.4, P < 0.001). Ethnically, Yau aboriginal populations had a significantly higher seroprevalence than did the Akka aborigines and Han people (P < 0.001).

Characterization by pulse-field electrophoresis of a new region of DNA amplification containing the M2 subunit of ribonucleotide reductase in hydroxyurea-resistant Leishmania

Abstract An extrachromosomal circular DNA of approximately 50-kb size was amplified in the hydroxyurea-resistant variant of Leishmania mexicana amazonensis. The amplicon carried the M2 gene of ribonucleotide reductase as part of the gene encoding resistance to hydroxyurea. The amplicon was unstable. It disappeared rapidly as shown in pulse-field gradient electrophoresis gels after reversion of the cells for 20–80 days. This loss of amplified DNA was accompanied by a rapid loss of resistance to hydroxyurea during the same period. The amplicon was not hybridized to specific probes from any of the four regions of DNA amplification previously reported for Leishmania. This region of amplification thus appears to be a new region of DNA amplification in Leishmania.

Infectivity and development of Metagonimus yokogawai in experimentally infected domestic ducks (Cairina moschata).

Information concerning whether fowl such as duck is a suitable reservoir host of Metagonimus yokogawai is largely unclear to date. In the present study, the growth and development of M. yokogawai metacercaria (Mc) in domestic duck (Cairina moschata) was determined by worm recovery rate (WRR) and morphological changes e.g., the size of flukes body as well as their internal organs was assessed by using Semichons acetocarmine staining. Each duck was orally inoculated with 50 Mcs of M. yokogawai and infected ducks were deeply anesthetized with ether and killed at 1, 2, 3, 4, 5, 6, 7, and 14 days post-infection (DPI). On each date, two infected ducks were killed and the small intestines of each duck were separated into four parts then they were opened longitudinally to harvest the flukes. Results revealed that WRR of M. yokogawai from inoculated ducks increased during early infection with a peak as seen at 4 DPI (28.5+/-6.9%); thereafter it gradually decreased and a drastic decline was observed in 14 DPI (2.0+/-1.1%) in the trial. The preference sites for M. yokogawai were low portions of the small intestine; nevertheless the size of flukes body and organs developed increasingly with time and they maturated to produce ova from 4 DPI onward in the trial. However, present results indicated that ducks, based on the findings of this study, are not suitable hosts for establishment of M. yokogawai infection because most flukes were expelled from ducks intestine within 14 days. Nevertheless, it was proposed that ducks might play a certain role in transmitting M. yokogawai when they deposited the ova via feces into marsh where snails and fish were abundant since they could presumably establish transient and possibly patent infections with this parasite.

Larval Migratory Behavior of Long-term-maintained Toxocara canis Embryonated Eggs in Mice

Larval migratory behavior of Toxocara canis embryonated eggs that had been maintained in 2% formalin for 14 months at 4℃ was evaluated using a larval recovery study in mice at between 1 and 469 days post infection (DPI) . Three infected mice and 2 aged-matched uninfected control mice were sacrificed daily for acid-pepsin digestion of the liver and lungs (hepatopulmonary phase) as well as the musculature and brain (myotropic-neurotropic phase). Larval recovery from the hepatopulmonary phase reached a peak at 5 DPI, not at 2 DPI; thereafter, they began to migrate to the myotropic-neurotropic phase. Statistically, larval recoveries from the hepatopulmonary and myotropic-neurotropic phases respectively showed negative and positive correlations with time (r = - 0.688, P = 0.005; r = 0. 138, P = 0.327). Altogether, although there seemed to be a delay in the migration of 14-month-cultured T. canis larvae to the hepatopulmonary phase, most of them still exhibited the myotropic-neurotropic phase, especially in the brain.

A RAB family antigen of Angiostrongylus cantonensis induces a Th1-type immune response in vitro and in vivo.

A cDNA library was constructed from an Angiostrongylus cantonensis young adult and the encoded proteins were expressed in Escherichia coli. One reactive antigen, a RAB-2 protein, was selected using an immunoscreening technique. The expression of the Th1-type cytokine IFN-γ was elicited in mouse splenic cells that were co-cultured with the recombinant RAB-2 protein and in the sera of mice that were immunised with this protein and adjuvant (50 μg at 2-week intervals). In the A. cantonensis-infected groups, the mice were orally infected with 35 infective larvae, and a subset of the infected mice were immunised with the recombinant RAB-2 protein in adjuvant. Serum samples were collected every week for ELISA, and the pathological examinations were performed at 14 days post infection (dpi). An increase in IFN-γ expression was noted in the blood, and the brain sections revealed moderate eosinophilic meningitis in the immunised mice. The RAB-2 antigen of A. cantonensis induced a Th1-type immune response both in vitro and in vivo.