Human diphyllobothriosis in Taiwan: A review of cases and molecular evidence of Dibothriocephalus nihonkaiensis

Diphyllobothriosis is an infectious disease caused by the consumption of raw freshwater or marine fish containing larvae of broad tapeworms (Diphyllobothriidae). In the present study, we critically reviewed all cases of human diphyllobothriosis reported from Taiwan, including unpublished reports from hospitals in Taipei. Genotyping based on mitochondrial DNA marker (cox1) confirmed that two of the recent cases were caused by Dibothriocephalus nihonkaiensis, which is not native to Taiwan and was probably imported with Pacific salmon infected with larvae of D. nihonkaiensis. The causative species previously reported in Taiwan could not be definitively confirmed. However, considering the distribution of Dibothriocephalus latus, which is not endemic in Taiwan, past cases diagnosed as D. latus are questionable.

Epidemiology, clinical features, and outcomes of strongyloidiasis in Taiwan from 1988 to 2020: A case series and literature review

OBJECTIVES

We described a case of Strongyloides hyperinfection syndrome, reported a case series, and reviewed published cases of strongyloidiasis in Taiwan.

METHODS

Confirmed cases of strongyloidiasis at the National Taiwan University Hospital (NTUH) and NTUH Hsin-Chu Branch from 1988 to 2020 were identified in the medical record database. Literature search was carried out through Pubmed, Google Scholar, and Index to Taiwan Periodical Literature System to identify published cases of strongyloidiasis in Taiwan from 1979 to 2020. Data pertaining to the demographics, underlying medical conditions, clinical manifestations, laboratory findings, and outcomes were extracted.

RESULTS

A total of 117 cases of strongyloidiasis were identified, including 20 previously unpublished cases from the two hospitals and 97 published cases in the literature. Overall, 85 (73%) were male and the mean age was 64 years (range, 6-95 years). Classical symptoms such as diarrhea, cough, and skin rash were only observed in 43%, 37%, and 18% of the patients, respectively, whereas eosinophilia at presentation was only found in 48%. Strongyloides hyperinfection syndrome and disseminated strongyloidiasis were identified in 41 (35%) and 4 (3%) patients, respectively. Four (3%) patients had concurrent meningitis. In univariable analysis, being older and having pre-existing chronic obstructive pulmonary disease or asthma were associated with hyperinfection or dissemination (p = 0.024 and 0.003, respectively). The mortality rate was 43% among those with hyperinfection or disseminated infection.

CONCLUSIONS

Strongyloidiasis can cause serious complications and mortality. Efforts to diagnose strongyloidiasis early are urgently needed to improve the outcome of patients with strongyloidiasis in Taiwan.

Association between transforming growth factor-β1 expression and the clinical features of triple negative breast cancer

The aim of the present study was to investigate the association between the expression levels of transforming growth factor-β1 (TGF-β1) and the clinical pathological characteristics and prognosis of triple negative breast cancer (TNBC) through study of TNBC patient tissue samples. The biological effects of TGF-β1 on TNBC cells and the potential signal transduction pathway are additoinally investigated. Immunohistochemistry was utilized to investigate expression changes of the positive rate of TGF-β1 in the TNBC, compared with the non-TNBC group, to explain the association between TGF-β1 and clinical pathological characteristics and prognosis. MDA-MB-231 cells were treated with TGF-β1 and subsequently the invasion and migration abilities, and the expression of proteins in certain signaling pathways were assessed before and after the treatment. Positive expression of TGF-β1 was observed in 52.5% of TNBC tissue samples, which was higher than that observed in non-TNBC group (27.5%). High levels of TGF-β1 expression were not significantly associated age, menopausal status, family history of cancer or tumor size; however, tumor histological grade and axillary lymph node metastasis were significantly associated (P<0.05). In addition, when the TGF-β1 expression levels are higher, the 5-year disease-free survival rate is lower. TGF-β1 expression promoted the invasion and migration of MDA-MB-231 cells, and the expression of Smad2 protein and P38 protein was increased, indicating that Smad2 protein and the P38 signaling pathway may serve an important role in TNBC.

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.

Brain injury-associated biomarkers of TGF-beta1, S100B, GFAP, NF-L, tTG, AbetaPP, and tau were concomitantly enhanced and the UPS was impaired during acute brain injury caused by Toxocara canis in mice

Background

Because the outcomes and sequelae after different types of brain injury (BI) are variable and difficult to predict, investigations on whether enhanced expressions of BI-associated biomarkers (BIABs), including transforming growth factor β1 (TGF-β1), S100B, glial fibrillary acidic protein (GFAP), neurofilament light chain (NF-L), tissue transglutaminases (tTGs), β-amyloid precursor proteins (AβPP), and tau are present as well as whether impairment of the ubiquitin-proteasome system (UPS) is present have been widely used to help delineate pathophysiological mechanisms in various BIs. Larvae of Toxocara canis can invade the brain and cause BI in humans and mice, leading to cerebral toxocariasis (CT). Because the parasitic burden is light in CT, it may be too cryptic to be detected in humans, making it difficult to clearly understand the pathogenesis of subtle BI in CT. Since the pathogenesis of murine toxocariasis is very similar to that in humans, it appears appropriate to use a murine model to investigate the pathogenesis of CT.

Methods

BIAB expressions and UPS function in the brains of mice inoculated with a single dose of 250 T. canis embryonated eggs was investigated from 3 days (dpi) to 8 weeks post-infection (wpi) by Western blotting and RT-PCR.

Results

Results revealed that at 4 and 8 wpi, T. canis larvae were found to have invaded areas around the choroid plexus but without eliciting leukocyte infiltration in brains of infected mice; nevertheless, astrogliosis, an indicator of BI, with 78.9~142.0-fold increases in GFAP expression was present. Meanwhile, markedly increased levels of other BIAB proteins including TGF-β1, S100B, NF-L, tTG, AβPP, and tau, with increases ranging 2.0~12.0-fold were found, although their corresponding mRNA expressions were not found to be present at 8 wpi. Concomitantly, UPS impairment was evidenced by the overexpression of conjugated ubiquitin and ubiquitin in the brain.

Conclusion

Further studies are needed to determine whether there is an increased risk of CT progression into neurodegenerative disease because neurodegeneration-associated AβPP and phosphorylated tau emerged in the brain.

Enhanced expression of transforming growth factor-beta 1 in inflammatory cells, alpha-smooth muscle actin in stellate cells, and collagen accumulation in experimental granulomatous hepatitis caused by Toxocara canis in mice

Although toxocaral granulomatous hepatitis (TGH) characterized with a dominant-Th2 type immune response is a self-limiting disease, little is known concerning the role of fibrosis-related cytokine transforming growth factor-beta 1 (TGF-beta 1) in pathogenesis of TGH. A detailed histological and quantitatively immunohistochemical analysis of TGF-beta 1, alpha-smooth muscle actins (alpha-SMA), and collagen was performed on the liver tissues from mice infected with Toxocara canis as assessed between day 1 and 42 weeks post-infection (DPI or WPI). TGF-beta1 was detected mainly in infiltrating leukocytes in lesions with strong expressions from 4 to 16 WPI. Larvae per se also exhibited strong TGF-beta 1-like molecule expressions in the trial. Alpha-SMA was detected predominantly in hepatic stellate cells (HSC) which surrounded the lesions with moderate expressions largely throughout the period of the entire experiment. Collagen was observed to accumulate in inflammatory lesions and biliary basement with moderate to strong expressions from 1 WPI onwards in the trial. Since many evidences have indicated that leukocytes have the potential to influence HSC by producing TGF-beta 1 which can affect HSC to increase collagen synthesis in various liver diseases, we may propose that persistently elevated TGF-beta 1 expression in infiltrating leukocytes and active HSC with marked alpha-SMA expressions may contribute to healing of injured sites through up-stimulation of collagen deposition; in contrast, abnormally persistent collagen accumulation may cause irreversible fibrotic injury in the TGH.

Suppression of host Th1-type granulomatous inflammation by Taenia solium metacestodes is related to down-regulation of osteopontin gene expression

Inflammation and granuloma formation in human neurocysticercosis has been attributed to Th1-type immune responses of the host. In the present murine model, over 94% of Taenia solium metacestodes were viable and elicited no granulomatous inflammation, whereas parasites killed by praziquantel treatment elicited rapid granuloma formation that calcified within 2weeks. Osteopontin (OPN) is a Th1-related cytokine that is up-stream of IL-12 and which may play an essential role in granuloma formation and calcification. OPN mRNA expression was down-regulated in tissues surrounding viable cysticerci, but was up-regulated in inflammatory tissues surrounding degenerating cysticerci. Moreover, co-culture with a viable cysticercus or ES products from these metacestodes led to a decrease in OPN, IFN-gamma and IL-12 expression, whereas co-culture with somatic proteins enhanced OPN expression by leukocytes. Addition of recombinant mouse OPN (rmOPN) counteracted the down-regulation of IL-12 and IFN-gamma mRNA expression, but not OPN mRNA expression, in leukocyte cultures. Furthermore, injection of rmOPN into the tissues surrounding implanted cysticerci enhanced inflammatory responses while a similar injection of an anti-rmOPN antibody reduced inflammation. These findings suggest that the suppression of host Th1-type granulomatous inflammation by ES products from T. solium metacestodes is related to down-regulation of OPN gene expression.

Seroprevalence of Toxoplasma gondii infection among inhabitants in the Democratic Republic of Sao Tome and Principe

The level of Toxoplasma gondii infection among the general population of the Democratic Republic of Sao Tome and Principe is unclear. The T. gondii infection status of inhabitants who visited National Central Hospital on Sao Tome Island was assessed by a latex agglutination test. The overall seroprevalence was 74.5% (120/161). No significant gender difference in seroprevalence was found between males and females. The older age group (> or =45 years) had significantly higher seroprevalence (80.0%, 28/35) than the younger age group (<15 years) (20.0%, 3/15) (chi(2)=16.04, P<0.001).

The origin of the triploid in Paragonimus westermani on the basis of variable regions in the mitochondrial DNA

Triploid, parthenogenetic forms of the lungfluke, Paragonimus westermani, occur in Japan, Korea and China. The origin(s) of triploidy has been debated over the years. Sequences of two regions in the mitochondrial DNA, i.e. partial lrRNA (16S), and a portion of the non-coding region, were obtained from natural populations of P. westermani. All triploid individuals (Japan, Korea, China) and a single tetraploid individual (China) had identical sequences in the 16S region studied. Some sequence variation was observed among diploids, with those from Taiwan being distinct from the remainder. Both neighbour joining and parsimony trees using the 16S region placed diploid individuals from southwestern Japan close to the triploids and the tetraploid. The fragment amplified from the mitochondrial non-coding region showed dimorphism. One form (type A) consisted of 239 bp comprising two identical tracts of 70 bp separated by a tract of 93 bp. The second form (Type B) consisted of only a single 70 bp tract. All diploid individuals from Taiwan, China and Korea possessed type A, while those from Japan were polymorphic; individuals from Oita and Hyogo had type B, those from Chiba had type A, but both types were found in Mie. On the other hand, all of the triploid individuals and two tetraploid individuals possessed type B. Both the form present in the non-coding region and the 16S sequence suggest an affinity between a south-eastern group of diploid populations in Japan and the triploid form. A possible mechanism responsible for the origin of the triploid is discussed.

Serological screening and toxoplasmosis exposure factors among pregnant women in the Democratic Republic of Sao Tome and Principe

The seroprevalence of Toxoplasma gondii infection among pregnant women in the Democratic Republic of Sao Tome and Principe (DRSTP) from November 2003 to March 2004 was determined by detection of serum anti-T. gondii antibodies. A short questionnaire interview for pregnant women was performed to investigate risk factors associated with T. gondii infection, including consumption of raw meat or unwashed vegetables, drinking unboiled water and keeping pets (cats and dogs). The overall seroprevalence of T. gondii infection was high (75.2%; 375/499). The older age group of > or =35 years had a significantly higher seroprevalence (85.7%; 54/63) than that of the younger age group of 15-25 years (70.4%; 178/253) (odds ratio 2.5, 95% CI 1.2-5.4; P=0.01). No significant difference in the seroprevalence of T. gondii infection was found between the pregnant women with and without exposure to the risk factors studied. However, among pregnant women with high antibody titers of > or =1:1024, it seemed likely that continual contact with pets and consumption of oocyst-contaminated water or raw unwashed vegetables rather than tissue cysts in meat was the primary route of infection. The incidence of congenital toxoplasmosis in unborn babies should be intensively monitored in the DRSTP.

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.

Trichomonas empyema with respiratory failure

Pulmonary trichomoniasis is rare, and few cases of trichomonas empyema have been reported in the literature. We describe a rare case of a non-immunocompromised 55-year-old man with Trichomonas empyema presenting with bilateral pleural effusion leading to respiratory failure. Examination of the pleural effusion showed numerous motile organisms by fresh wet preparation that were identified as Trichomonas species by Liu stain. The patient was successfully treated with metronidazole, ampicillin/clavunalate, fibrinolytic therapy, and thoracotomy decortication.

Angiostrongylus cantonensis: apoptosis of inflammatory cells induced by treatment with mebendazole or/and interleukin 12 in mice

Angiostrongylus cantonensis is the major cause of human eosinophilic meningoencephalitis. ICR mice were infected orally with 35 infective larvae and sacrificed at 4-14 days, 25 days or 32 days post infection (dpi) for pathological and immunocytochemical examinations. In the non-treated group, no apoptosis signal was found in the meninges or parenchyma of the brains (4-14 dpi). Only a few apoptotic cells were noticed at 25 dpi (3%) and 32 dpi (10%). In the groups, the animals were given a single dose of mebendazole (20 mg/kg, per os at various times) or injections of interleukin 12 (IL-12) (10 ng/daily, intraperitoneally), all the animals were sacrificed at 14 dpi; the number of apoptotic cells was increased (17-21%). In the group that received a single dose of mebendazole (4 dpi) in combination with IL-12 injections (4-13 dpi), mild meningitis was observed, and most of the infiltrated inflammatory cells were in the apoptotic program (55%). Taken together, apoptosis of the inflammatory cells (most were eosinophils) could be induced when the infected mice were treated with mebendazole or/and IL-12.

Seroprevalence of Toxoplasma gondii infection among pre-schoolchildren aged 1–5 years in the Democratic Republic of Sao Tome and Principe, Western Africa

The prevalence status of Toxoplasma gondii infection in children of the Democratic Republic of Sao Tome and Principe (DRSTP), Western Africa, is unknown to date. A serologic survey of T. gondii infection among pre-schoolchildren aged <5 years in the DRSTP was assessed by the latex agglutination (LA) test from November 2003 to March 2004. The overall seroprevalence of T. gondii infection was not low, reaching 21.49% (26/121). No significant gender difference in seroprevalence was found between boys (19.30%; 11/57) and girls (23.44%; 15/64) (chi2 = 0.31, P = 0.58). The older age group of 4-5 years had significantly higher seroprevalence (36.67%; 11/30) than the younger age group of <2 years (10.34%; 3/29) (chi2 = 5.64, P = 0.02). It was noteworthy that the majority of seropositive boys (90.91%; 10/11) or older children aged > or = 2 years (82.61%; 19/23) had high LA titres of > or = 1:1024, indirectly indicating acute Toxoplasma infection. This study is the first report indicating that T. gondii infection is not low in pre-schoolchildren aged <5 years in the DRSTP. Whether the DRSTP pre-schoolchildren acquire T. gondii infection through constant exposure to the parasite from their daily activities owing to poor environmental hygiene should be further evaluated.

Invasive amebiasis as an emerging parasitic disease in patients with human immunodeficiency virus type 1 infection in Taiwan

BACKGROUND

Whether risk of invasive amebiasis due to Entamoeba histolytica is higher among human immunodeficiency virus (HIV)-infected persons than uninfected persons remains unclear, although intestinal colonization by Entamoeba dispar is common among men who have sex with men. Our objective was to determine the prevalence of invasive amebiasis and intestinal colonization by E histolytica and E dispar in HIV-infected persons and uninfected controls.

METHODS

We assessed the prevalence of invasive amebiasis by case review of 951 HIV-infected persons and by serologic studies of 634 of the 951 HIV-infected persons, 429 uninfected controls with gastrointestinal symptoms, and 178 uninfected healthy controls using indirect hemagglutination antibody assay. We assessed the rate of intestinal colonization by E histolytica and E dispar by fecal antigen and polymerase chain reaction tests in 332 asymptomatic HIV-infected persons and 144 of the 178 uninfected healthy controls.

RESULTS

Forty-nine (5.2%) of 951 HIV-infected persons had 51 episodes of invasive amebiasis. A high indirect hemagglutination antibody titer was detected in 39 (6.2%) of 634 HIV-infected persons compared with 10 (2.3%) of 429 uninfected controls with gastrointestinal symptoms and 0 of 178 uninfected healthy controls (P<.001). Stool specimens from 40 (12.1%) of 332 HIV-infected persons and 2 (1.4%) of 144 uninfected healthy controls were positive for E histolytica or E dispar antigen (P<.001). Ten (25.0%) of the 40 antigen-positive stool specimens from HIV-infected persons contained E histolytica.

CONCLUSION

Persons infected with HIV in Taiwan are at increased risk for invasive amebiasis and exhibit a relatively high frequency of elevated antibody titers and intestinal colonization with E histolytica.

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 (> or =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.

Enhanced expression of transforming growth factor-?1 in inflammatory cells and secretory granules in Paneth cells in the small intestine of mice infected with Toxocara canis

The small intestine is the initial organ which Toxocara canis larvae invade. Information on intestinal pathological changes associated with transforming growth factor-beta1 (TGF-beta1) and secretory granules (SG) in Paneth cells (PCs) caused by T. canis is unclear. Mice orally inoculated with 250 T. canis infective eggs were evaluated by pathological and immunohistochemical assessments with a 294-day investigation. Pathologically, the inflammatory reactions with or without trapped larvae in the submucosa were observed only within the first 28 days post-infection (DPI), with inflammatory injury ranging from severe during 2 DPI to mild between 7 and 28 DPI. The crypts of Leiberkuhn were major larval penetration sites. Enhanced expression of SG in PCs appeared earlier than those of TGF-beta1 in infiltrating cells. The significance of both effectors might be related to the host's defense against larval invasion in the intestinal phase of toxocaral infection.

Cross-reactions with Ascaris suum antigens of sera from mice infected with A. suum, Toxocara canis, and Angiostrongylus cantonensis

Ascaris suum larval excretory-secretory (AsES) antigen and larval (AsLA) as well as adult somatic antigen (AsAA) which were thought to be possibly helpful in the diagnosis of visceral larva migrans (VLM) due to A. suum infection were investigated in the present study. Serum taken from mice orally inoculated with approximately 250 embryonated eggs of A. suum or Toxocara canis, or 40 third-stage larvae of Angiostrongylus cantonensis were assessed by enzyme-linked immunosorbent assay (ELISA) using the AsES antigen, AsLA or AsAA at 1, 2, 3, 4, 6 and 8 weeks post infection (WPI). The titer of serum IgG from mice infected with A. suum increased from 1 WPI and a peak at 4 WPI was observed when it reached approximately three times the level of uninfected control mice. Thereafter, it decreased gradually but remained high as found from 6 to 8 WPI. No cross-reactions of heterologous serum IgG against AsES antigen was observed, whereas heterologous serum IgM exhibited significant cross-reactions to AsES antigen. Cross-reactivities to AsLA and AsAA by heterologous serum IgG as well as IgM antibodies were also observed in the trial. Altogether, the AsES antigen apparently seemed to be superior to the other two somatic antigens when used in the diagnosis of A. suum-induced VLM with serum IgG as tested by ELISA. Moreover, it was the first report to test the possibly antigenic cross-reactivity between A. suum and A. cantonensis.

Seroepidemiology of Toxocara canis infection among mountain aboriginal adults in Taiwan

Seroepidemiology of Toxocara canis infection among adults of one ethnic Han and five aboriginal populations residing in mountainous areas of Taiwan was conducted by detecting serum IgG (>/=1:64) using a T. canis larval excretory-secretory antigen-based enzyme-linked immunosorbent assay. A short questionnaire interview was conducted to obtain data concerning their age, sex, occupation, consumption of raw pig liver, and possession of dogs. The overall seroprevalence (46.0%, 247 of 537) in the five aboriginal populations was significantly higher than that of ethnic Han population (30.2%, 13 of 43) (P = 0.04). Age, but not sex, seemed to be a factor related to positive serology. Aboriginal adults who had histories of eating raw pig liver (odds ratio [OR] = 1.65, P < 0.01), raising dogs (OR = 1.76, P < 0.01), or whose occupation was a laborer (OR = 1.78, P < 0.01) seemed to be more apt to be infected by T. canis than those without such histories and unemployed persons.

Prevalence of Pediculus capitis infestation among school children of Chinese refugees residing in mountanous areas of northern Thailand

An epidemiologic survey of Pediculus capitis infestation among Akka aboriginal and Han children of Chinese refugees living in mountainous areas at elevations of 1,100 to 1,400 m in Chiang-Rai Province of northern Thailand was conducted during January 2003. Of the 303 children examined, 43 (14.2%) had P. capitis infestation. The overall infestation rate for P. capitis in Akka children (29.3%, 12/41) was significantly higher than that in Han children (11.8%, 31/262; chi2 = 8.161, p = 0.002). The prevalence in Akka (52.2%, 12/23) and Han girls (19.7%, 31/157) was higher than that in Akka (0%) and Han boys (0%), respectively (p < 0.001), and the prevalence was higher in Akka girls than in Han girls (chi2 = 10.978, p = 0.001). The high prevalence of P. capitis infestation among these girls was possibly due to poor environmental hygiene and unavailability of sufficient water.

Serological Survey of Toxoplasma gondii Infection Among Slaughtered Pigs in Northwestern Taiwan

A serological survey of Toxoplasma gondii infection among slaughtered pigs in the largest slaughterhouse located in Taoyuan County of northwestern Taiwan was conducted using the latex agglutination (LA) test during 1998. The overall seroprevalence of T. gondii infection was 28.8% (32/111) with LA titers of 1:32 (6, 18.8%), 1:64 (10, 31.2%), 1:128 (9, 28.1%), 1:256 (6, 18.8%), and 1:512 (1, 3.1%). No significant difference (P > 0.05) in seroprevalence between male (28.6%, 20/70) and female (29.7%, 12/41) slaughtered pigs was observed. A decreasing trend in the seroprevalence among slaughtered pigs examined in the same slaughterhouse was observed because of a lower seroprevalence (P < 0.05) than that (44.4%, 128/288) previously reported about 10 yr ago using the LA test. Nevertheless, it is important to avoid eating raw or undercooked pork in order to prevent the acquisition of T. gondii infection among people in Taiwan.

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).

Combined treatment with interleukin-12 and mebendazole lessens the severity of experimental eosinophilic meningitis caused by Angiostrongylus cantonensis in ICR mice

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.

Infectivity and pathogenicity of 14-month-cultured embryonated eggs of Toxocara canis in mice

Infectivity and pathogenicity to mice of embryonated eggs of Toxocara canis, that had been maintained in 2% formalin for 14 months at 4 degrees C, were evaluated by immunological and pathological assessment at 1, 4, 8, 12, 16, 20, 24, 28, 42 and 67 weeks post-infection (WPI). On each date, three infected mice and two age-matched uninfected mice were sacrificed for serum collection and histological processing of the liver, lungs, musculature, and brain. Infectivity assessment by enzyme-linked immunosorbent assay (ELISA) revealed that the overall immunological pattern of infected mice tended to be towards the Th2 type response. Serum IgG1 antibody titers in infected mice were significantly higher than that of the uninfected control mice throughout the trial (P<0.05). On the other hand, no significant difference in titers of IgG3 antibody, an indicator for the Th1 type response, was observed between the infected and control mice, except at eight WPI (P<0.05). Pathogenicity was assessed semiquantitatively by comparing the mean number or diameter of inflammatory foci as well as histopathological changes in the liver, musculature, brain, or lungs of the infected mice and the control mice. Each hematoxylin and eosin (H&E) stained tissue section slide was examined under 100x magnification and 15 random fields were counted. Degree of inflammatory injury among the four organs was scored and categorized into four levels: normal (0), mild (1+), moderate (2+), and severe (3+). An index of inflammatory injury (mean score of experimental group/mean score of 10 control groups of 20 uninfected mice) of 2-3 is considered as moderate to severe, 1-2 as mild to moderate, and 0-1 as normal to mild. Histopathological changes were moderate to severe in the liver and lungs, mild to moderate in the musculature, and only normal to mild in the brain throughout the trial. It is noteworthy that apocrine-like change in epithelial cells of the bile duct was observed in most of the infected mice from eight WPI onward. Furthermore, larvae trapped by organized granulomas were found in soft tissue near the musculature at 12, 20, and 28 WPI. Altogether, not only were the infectivity and pathogenicity of the 14-month-cultured T. canis embryonated eggs retained, the hatched larvae were also capable of eliciting some special pathological changes in the murine host.

Seroepidemiology of Toxoplasma gondii infection among two mountain aboriginal populations and Southeast Asian laborers in Taiwan

A seroepidemiological survey of Toxoplasma gondii infection among Atayal and Paiwan mountain aborigines and Southeast Asian laborers in Taiwan was assessed from February 1998 to July 2000 using a latex agglutination test. To determine risk factors for T. gondii infection among Taiwan aborigines, the consumption of raw meat and valley water were given particular attention in a self-administered questionnaire. The overall seroprevalence of T. gondii infection was 19.4% for Atayal, 26.7% for Paiwan, 42.9% for Indonesian, 14.7% for Thai, and 11.3% for Filipinos. No significant gender difference in seroprevalence was found among Atayals, Paiwans, Indonesians, and Filipinos (P > 0.05). In the Thai group, however, males had a higher seroprevalence than females (P < 0.001). Results of the multiple logistic regression analysis indicate a higher odds ratios (OR) with age in both aboriginal groups. In contrast, the OR was lower among older Indonesians and Thais. Those Atayals and Paiwans with a history of eating raw meat seemed more susceptible to T. gondii infection than those who had never consumed raw meat. Ethnically, a significant difference in seroprevalence was observed between Indonesians and Paiwans, Atayals, Thais, and Filipinos (P < 0.001).

Seroepidemiologic survey of Dirofilaria immitis infection among domestic dogs in Taipei City and mountain aboriginal districts in Taiwan (1998-1999)

To estimate the seroprevalence of Dirofilaria immitis infection in domestic dogs in Taiwan, we utilized a commercial ELISA kit (Snap, IDEXX, USA) for detecting circulating antigens released by adult female worms. Serum specimens of 664 domestic dogs sampled from Taipei City in northern Taiwan and 14 mountain aboriginal districts in eastern Taiwan were screened for D. immitis antigens. Multivariate-adjusted odds ratios (ORs) with their 95% confidence intervals (CIs) were estimated by multiple logistic regression analysis. A total of 89 subjects were antigen-positive, giving a seroprevalence of 13.4%, of which the seroprevalence in Taipei City and mountain aboriginal districts were 13.8 and 12.1%, respectively. The mean overall seropositive rates were 6.3% in 1-3-year-old age group, 14.1% in 3-6-year-old age group and 23.7% in the > or =6-year-old age group. The older the age, the higher the seroprevalence (OR=4.6, 95% CI=2.4-9.0 for the > or =6-year-old age group versus 1-3-year-old age group, P<0.001) for all the dogs in the present study. Moreover, seroprevalence was not different between female and male dogs in either Taipei City or mountain aboriginal districts (P>0.05). Also, no significant difference in seroprevalence among dogs between the two geographical areas was found (P>0.05). In the logistic regression analysis, the seroprevalence of D. immitis remained significantly increased with age after multivariate adjustment in the present study. To our knowledge, this is the first report on the status of D. immitis infection in domestic dogs in Taipei City and mountain aboriginal districts in Taiwan to date.

Toxoplasma gondii infection: relationship between seroprevalence and risk factors among inhabitants in two offshore islands from Taiwan

A seroepidemiological study of toxoplasmosis among inhabitants of Penghu Island and Kinmen Island offshore of Taiwan was performed using the latex agglutination test from July 1999 to June 2000. In order to determine risk factors for Toxoplasma gondii (T. gondii) infection, the effects of a history of eating raw/undercooked meats and raising pets were focused on using a self-administrated questionnaire. The seroprevalence (28.2%; 190/673) in Kinmen Island was significantly higher than that (2.71%; 8/293) in Penghu Island (P < 0.001). A significant difference in seroprevalence between both sexes was found in Kinmen Island (P < 0.05), but not in Penghu Island. The results of multiple logistic regression analysis showed that the older the age, the higher the OR in both Islands, yet a significant difference in seroprevalence between children and adults or the elderly was observed in Kinmen Island (P < 0.001). Moreover, those who had histories of raising cats or eating raw/undercooked meats seemed to have greater opportunities to become infected with T. gondii (OR = 2.9, 95% CI = 1.9-4.5, P < 0.001; OR = 1.5, 95% CI = 1.1-2.1, P < 0.05). In Penghu Island, a significant association between seroprevalence and a history of raising cats was also observed (OR = 4.6, 95% CI = 1.1-20.1, P < 0.05). Furthermore, workers, farmers, and fishermen seemed to be more susceptible to T. gondii infection than students in Kinmen Island.

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

An extrachromosomal circular DNA of of approximately 50-kb size was amplified in the hydroxyurea-resistant variant of Leishmania mexicana amazonensis. The amplicon carried the M2 gene of ribonuleotide 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.

Worm recovery and precipitin antibody response in guinea pigs and rats infected with Clonorchis sinensis

Guinea pigs (Hartley strain) and rats (Wistar strain) were each fed 200 and 100 Clonorchis sinensis metacercariae, respectively. Five animals from each species were sacrificed weekly between 1-8 weeks postinfection (WPI) and then at 12, 16, 20 and 30 WPI for collection of worms, bile and sera. The overall worm recovery rates for guinea pigs and rats were 18.7% and 12.4%, respectively. Only one of the five rats examined at 20 WPI still harbored one worm, while all were worm-free at 30 WPI. By a double diffusion test, no antibodies were detected against C. sinensis adult antigens in the bile juice. Serum antibodies were detected in at least 95% of the infected guinea pigs between 4-30 WPI and rats between 3-16 WPI. Precipitin antibodies seemed to be correlated with the presence of live worms in rats that had been infected for more than 12 weeks.

[Seroepidemiology of Toxoplasma gondii infection among Atayal aborigines and local animals in Nan-ao district, Ilan county and Jen-ai district, Nan-tou county, Taiwan]

In this study, latex agglutination test (LAT) was used to detect sera anti-toxoplasma antibodies of Atayal aborigines and local animals in Nan-ao district, Ilan county and Jen-ai district, Nan-tou county as a measure of exposure to the Toxoplasma gondii. Out of 422 Atayal aborigines and 64 different animals were tested in Nan-ao district and 82 Atayal children in Jen-ai district were also screened, the positive rates for sera anti-toxoplasma antibodies were 21.8%, 17.2% and 15.9%, respectively. In Nan-ao district, neither were the positive rates significantly different in males (22.1%) and females (21.4%), nor in humans (21.8%) and dogs (19.6%) (P > 0.05). The seroprevalence in adults (28.3%) was significantly higher than that in children (18.7%) (P < 0.05), and the highest seropositive rate (38.1%) was in the age group 50-59 years and the lowest (7.7%) was in the age group 1-9 years. In general, the age pattern of prevalence is consistent with increasing duration of exposure to Toxoplasma gondii with age. For animals, the seropositive rate in dogs (19.6%) was also significantly higher than that in wild rats (7.7%) (P < 0.05). No significant difference in seropositive rate of Atayal children was observed between Nan-ao and Jen-ai districts (P > 0.05).

Seroprevalence of Toxoplasma gondii antibodies among Atayal aboriginal people and their hunting dogs in northeastern Taiwan

Atayal aborigines, living at an altitude of 1,500-1,600 m in northeastern Taiwan, still hunt for wild animals with the help of hunting dogs. In this study, the latex agglutination test (LAT) was used to detect sera anti-toxoplasma antibodies in this community as a measure of their exposure to Toxoplasma gondii. The positive rates for sera anti-toxoplasma antibodies were 21.8% and 19.6%, respectively, in 422 Atayal and 51 hunting dogs tested. Neither of the positive rates were found to be significantly different between male (22.1%) and female Atayal (21.4%), or between humans (21.8%) and dogs (19.6%) (P > 0.05) when compared by the Chi-Squared test (chi 2-test). A significant difference was observed between the positive rates in adults (28.3%) and children (18.7%) (P < 0.05), and the age pattern of prevalence is consistent with an increasing duration of exposure to Toxoplasma gondii with age. The consumption of raw liver of wild animals or insufficiently cooked meat may be the major mode of transmission of toxoplasmosis in Atayal.

[Larval distribution in different organs of ICR strain mice infected with Toxocara canis]

In this study 80 ICR mice were infected per os with 260 embryonated Toxocara canis eggs each through a stomach tube. Ten mice were sacrificed at weekly intervals over an eight-week period. Internal organs including livers, lungs, hearts, spleens, kidneys, brains, and carcasses were pooled separately and T.canis larvae from each category treated with artificial digestive fluid were recovered and later collected by the Baermann technique. Larval distributions at a given week in different organs or in a given organ at different weeks were compared and analyzed. Results revealed that total larval recovery increased from week one (11.6%) to four(19.7%); thereafter it decreased gradually and dropped to 13.4% by week eight. Larval distribution in different organs varied with time. No larvae were recovered from the heart or spleen during the study period, except for a small number recovered from the spleen in the 4th and 5th weeks after infection. In general, the larvae were recovered mainly from the brain, carcass and liver. Larval recovery from the liver was high in the first two weeks (4.5% and 3.6%, respectively) and in week 4(5.6%). Recovery from the brain increased drastically in week 4(6.8%) and remained high. Recovery from the carcass increased with time. In the case of the lungs, a sharp peak was observed in week 3(4.8%), but recovery from the kidneys was low (0.7-1.6%). Our results indicated that the ICR strain mouse is also a suitable animal model for the study of toxocariasis in paratenic hosts.

Studies on cryopreservation of Toxoplasma gondii and its antigenicity in mice

Two strains (RH and GC, the latter of which is a Taiwan isolate of porcine origin) of Toxoplasma gondii were kept at -20 degrees C, -60 degrees C, and in liquid nitrogen (-196 degrees C) to follow the time course change in viability and virulence of the parasites by direct count and animal inoculation methods. Changes in antibody titers in some of the mice inoculated with the thawed organisms were assayed by the indirect immunofluorescent antibody test. Viability and virulence of T. gondii were best preserved by storage in liquid nitrogen. Tachyzoites kept in liquid nitrogen for eight years still can lead to the death of the injected mice in 2-3 weeks. Virulence of the tachyzoites could be maintained for eight weeks at most at -20 degrees C and -60 degrees C. Dimethylsulfoxide (DMSO) seemed to be a better cryoprotectant for T. gondii than glycerol, but the DMSO-preserved organisms resulted in fewer tachyzoite-containing peritoneal exudates in inoculated mice than the glycerol-preserved organisms. The local isolate (GC strain) tachyzoites tolerated cryopreservation less well than the RH strain parasites. Low antibody titers (at most 1:64) were produced in mice that survived more than 16 days after inoculation with thawed tachyzoites.

[Application of staphylococcal protein A for immunodiagnosis of early toxoplasma infection]

RH strain Toxoplasma gondii was used to inoculate mice and rats. Sera collected at intervals were assayed by the indirect fluorescent antibody test (IFAT) and the latex agglutination test (LAT) to monitor the time-course change in titers of anti-toxoplasma IgM and IgG antibodies. In addition, the above sera and some anti-toxoplasma seropositive human sera (with IFAT antibody titers greater than or equal to 1:16) were adsorbed with staphylococcal protein A (SpA) and assayed for changes in IgM and IgG antibody titers so as to evaluate the usefulness of SpA adsorption in detecting anti-toxoplasma IgM which shows up early in toxoplasma infections. Samples assayed included 262 sera from mice, 65 sera from 5 rats and 85 human sera. The results revealed that parasite specific IgM-IFAT antibodies were detectable in 40% of the sera from mice 3 days after infection. After SpA adsorption, however, the IgM-IFAT antibody could be detected in a few specimens as early as 2 days post infection. IgG-IFAT and LAT antibodies first appeared in the sera on the 5th day of infection. In mice inoculated with freeze-killed tachyzoites (immunized mice), IgG-IFAT and LAT antibodies remained high from 16-35 days after inoculation, whereas IgM-IFAT antibodies were undetectable. Even after SpA treatment, only about half of the 16-day samples showed IgM antibody titers and the other specimens still remained negative. In general, IgM antibody titers increased 2-6 fold after SpA adsorption while IgG antibodies were almost completely removed after the treatment with a residual IgG-IFAT titer of less than or equal to 1:4.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibody to Trichomonas vaginalis in human cervicovaginal secretions

Human cervicovaginal secretions were obtained from patients at the Gynecology and Obstetrics Clinics at National Taiwan University Hospital and Cathay General Hospital, Republic of China. Among the 500 patients examined, 33 (6.6%) were infected with Trichomonas vaginalis as determined by the culture method. Secretions from 24 of the infected patients and 30 noninfected women were assayed for anti-T. vaginalis immunoglobulins by the indirect immunofluorescent antibody technique. A few serum samples from both infected and noninfected persons were also included in this study. Immunoglobulin G (IgG) antibody against T. vaginalis was detected in 17 (70.8%) secretions from the infected women. Among the 17 positive secretions, anti-parasite IgA was found in two specimens, IgE was found in three, and IgM was found in one. Of the 30 secretions, 7 (23.3%) from noninfected women also contained anti-parasite IgG. Low levels of natural anti-trichomonad IgG and IgM were detected in the sera of normal persons. Infection with T. vaginalis caused an increase in the serum IgG antibody titer. Cross-reaction between T. vaginalis and Pentatrichomonas hominis was also observed.