Study of the morphological characteristics of Schistosoma mansoni in mice, squirrels, and hamsters

This study attempted to describe mophological characteristics of S. mansoni worms. In the present study, 6 hamsters, 35 squirrels and 141 mice were infected with pooled cercariae of Schistosoma mansoni by intraperitoneal and percutaneous routes. The worm recovery rate was 18.2% (257/1,412) in hamsters (Mesocricetus auratus); 10.1% (3,310/32,792) in squirrels (Callosciurus erythraeus roberti) and 16.2% (4,328/26,720) in mice (Swiss strain). There were no significant differences between the sizes of 332 adults studied from three kinds of experimental animals. However, the worms collected from the hepatic portal system were usually larger than those from the peritoneal cavity because the latter almost always remained in the immature stage. We found male S. mansoni with tandem (17-22%), non-tandem (80-83%) and unusual/irregular arrangement (3-5%) of testes. The number of S. mansoni testes found were from 3 to 15 in mice, 3 to 11 in hamsters and 4 to 15 in squirrels. Mature worms had a tendency to reduce their size with aging. The number of S. mansoni cecal loops were from 1 to 5 in mice and hamsters and 1 to 4 in squirrels. The location of the first cecal loop was usually in the anterior part of body (1/4 in females and 1/3 in males), but there were some exceptions. The number of eggs in the uterus of each female worm, were 0-3 in mice, 0-1 in squirrels and hamsters. The average number was 0.75. The location of the ovary was usually situated in the anterior part of body of the worm in the three kinds of experimental animals. A few mated male and female worms of S. mansoni being free in the peritoneal cavity were found to develop to sexual maturity, because eggs were observed in their uteri. Their size was usually found to be considerably smaller than the worms seen in the hepatic portal system, and they had no hematin in their intestinal ceca. Encapsulated eggs were found from the peritoneal cavities of a few mice following intraperitoneal and percutaneous methods of infection.

Annual economic loss caused by Taenia saginata asiatica taeniasis in East Asia

Taeniasis is an important medical and economic problem in many countries in East Asia, especially in the mountainous and remote areas where the inhabitants are fond of eating raw or undercooked meat. P.C. Fan here discusses how sociocultural factors and local customs can contribute to the transmission of taeniasis and evaluates the economic losses caused by the disease.

Taiwan taenia and taeniasis

Toeniids are large tapeworms, common throughout the world. Two species, Taenia saginata and T. solium are common parasites of man. The adult worms parasitize the small intestine, while immature stages (metacestodes or cysticerci) develop mainly in cattle in the case of T. saginata or pigs in the case of T. solium. Cysticerci of T. saginata rarely develop in man, although humans are easily infected with those of T. solium after eating raw or undercooked infected pork-producing the disease known as cysticercosis. In Taiwan, both the pork and beef tapeworms have been documented among aboriginal peoples - with T. saginata considered the most prevalent species. But, as P.C. Fan discusses here, the 'Taiwan Taenia' has several unusual features - not least the fact that beef is not part of the traditional diet of Taiwan oboriginols.

Hybridization of Schistosoma mansoni and Schistosoma japonicum in mice

Crossing experiments in mice with two human species of Schistosoma japonicum (Taiwan strain) and Schistosoma mansoni (Puerto Rican strain) were performed. The hybrid miracidia from the cross between female S. japonicum and male S. mansoni infected both Biophalaria glabrata and Oncomalania h. chiui. However, those from the reciprocal crossing could infect only B. glabrata. B. glabrata infected with hybrid miracidia of female S. mansoni x male S. japonicum survived up to 30 days while those infected with miracidia of S. mansoni remained alive for more than 100 days after the first shedding of cercariae. Relatively few hybrid eggs reached maturity either in tissues or in the feces of infected mice. A low percentage of F1 eggs hatched and the infectivity of F1 miracida was also low. Morphology and behavior of hybrid eggs, miracidia, cercariae, and adults were similar to the maternal species. The daily egg production of the hybrid worm pair was less than that of the normal one. The observations in the present study may be attributed to the maternal effects. However, the phenomenon of parthenogenesis in schistosomes cannot be confirmed.

Infectivity and development of the human strain of Hymenolepis nana in ICR mice

In order to study the infectivity and development of the human strain of Hymenolepis nana in mice, a human strain of H. nana was inoculated into ICR mice. H. nana eggs were concentrated by the sedimentation method and inoculated by a disposable syringe (1 ml) connected to a long needle (8 cm) into the stomach of mice. Mouse feces were examined daily beginning day 5 after inoculation and the mice were sacrificed from days 19 to 65 post-infection (PI). The infection rate and worm recovery rate were 69% and 17%, respectively. The prepatent period ranged from 7 to 23 days. Autoinfection was found to occur in an ICR mouse infected with 60 eggs; 102 worms were recovered from its small intestinal lumen on day 19 PI. One row of hooklets was found on the scolex and the mean number of hooks was 19. The average length, width, and number of segments were 51 mm, 0.6 mm, and 1,099, respectively. The mean length and number of immature segments were 9 mm and 414 segments, mature segments 20 mm and 390 segments, and gravid segments 22 mm and 295 segments. The average length, width, and number of segments in 26 autoinfected worms were 11.5 mm, 0.3 mm, and 189 segments. The mean length and number of immature segments were 3.9 mm and 41 segments, mature segments 4.4 mm and 65 segments, and gravid segments 3.2 mm and 83 segments, respectively.

Egg production capacity of one-pair worms of Schistosoma japonicum in albino mice

In the present study, a series of procedures of egg count were carried out to determine the egg production capacity in 21 ICR mice each infected with one-pair of Schistosoma japonicum. The egg count began from the first day, they were detected in the feces, which was based on a stool collection over 24 hours, twice a week. Each female S. japonicum produced an average of 2,198 eggs/day during the study period of 99 days after infection (ranged 61-147 days). Fourty-seven percent of the eggs were in the feces and 53% in tissues (45% in large intestine, 31% in small intestine, 23% in liver, 0.4% in pancreas, 0.2% in lungs, 0.1% in spleen, 0.1% in lymph nodes, 0.06% in stomach and 0.05% in heart, kidney, diaphragm and brain).

School-aged children with Kawasaki disease: high incidence of cervical lymphadenopathy and coronary artery involvement

OBJECTIVE

We describe 10 school-aged children with Kawasaki disease (KD) with a high incidence of cervical lymphadenopathy and coronary abnormality.

METHODS

Based on a database of 1002 children with KD in Chang Gung Children's Hospital from January 1983 to March 2001, 10 (1%) school-aged patients (five boys, five girls) who met the diagnostic criteria of KD were included for analysis.

RESULTS

Cervical lymphadenopathy was noted in all (100%) of these patients. Unilateral neck mass mimicking acute suppurative infections not responding to antibiotic therapy was the initial presentation in nine (90%) of the 10 patients. The mean interval between disease onset and diagnosis was 9.9 +/- 3.3 days (range, 6-15 days). Seven (70%) of these patients responded to one course of high-dose intravenous immunoglobulin (IVIG) therapy (2 g/kg) and oral aspirin (80-100 mg/kg per day), two (20%) required a second course of IVIG, and one (10%) responded to high-dose aspirin treatment only. Coronary artery abnormality (dilatation or aneurysm) was documented by echocardiography in seven (70%) patients (four boys, three girls). In six patients, the coronary artery abnormalities resolved in 1 year, while one patient had persistent right coronary artery aneurysm, which necessitated continued anticoagulant and low-dose aspirin therapy.

CONCLUSION

The incidence of school-aged children among patients with KD is about 1% in our hospital. These patients are notable for the high incidence of initial manifestations of unilateral neck mass and coronary artery involvement. This disease should be listed as the differential diagnosis in school-aged children presenting with fever and neck mass that do not respond to antibiotic therapy.

Studies on abnormality of metacestodes and adult worms of Taenia solium and Taenia saginata asiatica in rodents and pigs

Abnormalities are not uncommon in Taenia saginata and T. solium. After examining 328 mature proglottids from 2 adult worms from two experimentally infected hamsters, 13 (4.0%) were found to have no genital pore but with numerous testes and several vas efferents; 1 (0.3%) one genital pore with one reproductive system; 12 (3.7%) one on each side with two sets of reproductive system; 17 (5.2%) two on one side with 2 sets of reproductive system; 8 (2.4%) one on one side and two on the other side with 3 sets of reproductive system; 2 (0.6%) two on each side with 4 sets of reproductive system; 4 (1.2%) three on one side with 3 sets of reproductive system, and 4 one on one side and three on the other side with 4 sets of reproductive system. Nine evaginated abnormal cysticerci of T. s. asiatica from three experimentally infected SCID mice each had two protoscoleces and a big bladder. From two experimentally infected pigs, one abnormal cysticercus was observed to have two invaginated canals each in one end. Another one had a neck-band behind the scolex and a big bladder. This paper is not only the first report of abnormality of T. solium from hamster but also the first one of abnormal cysticerci of T. s. asiatica from pigs and mice.

A sieving method for collecting the metacercariae of trematode parasites from freshwater fish

This study describes a sieving method for the collection of metacercariae from frozen (-20 degrees C) freshwater fish. Digested fish tissue is filtered through a series of sieves; the crude filtrate is then centrifuged. Centrifugation produces a sediment from which metacercariae can be removed. Half of the metracercariae that were obtained from the fish meat that had been frozen for 10 days (-20 degrees C) were dead; the other half were alive and some larvae were moving slowly.

Experimental studies on physiological and morphological aspects of Cysticercus cellulosae in pigs

Three Small-Ear-Miniature, 3 Landrace-Small-Ear-Miniature, and one Douc-Yorkshire-Landrace pigs were inoculated orally with 100 000 eggs of Zhengzhou strain or 10 000 eggs of Harbin strain of Taenia solium. A total of 3739 cysticerci were recovered from 3 Small-Ear-Miniature and 3 Landrace-Small-Ear-Miniature pigs, giving an infection rate of 85.7% and a cysticercus recovery rate of 1.1%. The predilection sites of Cysticercus cellulosae in descending order were leg muscles, abdominal muscles, thoracic muscles, liver, head muscles, diaphragm, tongue, heart, trachea, and omentum/testes. Except 2 calcified cysticerci in the tongue, 2 in the heart, and 176 in the liver, the remaining cysticerci were all alive. The greatest number of cysticerci per 100 g of muscles or viscera was found in the head muscles, followed by the leg, diaphragm, heart, tongue, thoracic, abdominal, omentum, testes, and trachea. All cysticerci were evaginated in pig's bile after fluid was drawn out from cysticerci, whereas evagination occurred in only 83.2% of those without fluid drawing. In 364 evaginated cysticerci, the mean length and width of scolex, proglottid, and bladder, and diameter of rostellum and sucker were 826 x 747 microm, 5,370 x 1,734 microm, 2,885 x 3,002 microm, 155 microm, and 253 microm, respectively. In the protoscolex, the mean number of segments was 33. Each cysticercus had 2 rows of rostellar hooks on the scolex, and the mean length and width of inner and outer hooks were 151 x 18 microm and 117 x 14 microm, respectively. The number of paired hooks ranged from 10 to 18.

Current status of imported parasitic infection among foreign workers in northern Taiwan (1999-2000)

In the present study, a simple, economic and practical technique was employed for stool examination. Of a total of 6,146 fecal samples from foreign workers in Northern Taiwan between 1999 and 2000 were examined, 615 were found to be positive for parasitic infection and the overall infection rate was 10%. Newly arriving foreign workers had a significantly higher infection rate (15%) than those who had worked in Taiwan for 6-12 months (8%). The foreign workers came from Indonesia, Philippines, Thailand, Malaysia, and Vietnam. Except for the small number of workers from Malaysia which was not included, the infection rate order by nationality was Vietnamese (21%) > Indonesian (13%) > Philippino (10%) > Thai (4%). The female examined workers were about 3-fold of males and their infection rate (11%) was also significantly higher than the males (5%). The order of rates by age was 20-30 years (11%) > 31-40 years (8%) > 41-50 years (5%). According to the species of parasites, 569 foreign workers were infected with 1 species (9%) > with 2 species (0.7%) > with 3 species (0.1%). Totally, 14 species (10 helminths including 1 plant nematode, Heterodera and 4 protozoa; hookworm might include 2 or 3 species, but counted as one species here) were found, of which 10 species were pathogenic (9 helminths and 1 protozoa) and 4 non-pathogenic. Foreign workers from Indonesia harbored 12 species of parasites > from the Philippines, 9 species > from Thailand, 8 species > from Vietnam, 7 species.

Experimental studies on small hooks preceding large hooks in the growth and development of Taenia solium metacestodes

In the present study, we have determined the growth and development pattern of rostellar hooklets of Taenia solium cysticerci (Zhengzhou and Harbin strains) in three pigs (1 SEM and 2 L-SEM strains) 89-196 days post experimental infection. A total of 3,675 cysticerci were collected from 3 pigs, 3,007 (82%) of 3,675 cysticerci were evaginated by enzyme method. 439 (15%) evaginated cysticerci were carefully examined and measured after dehydration, staining, and mounting on microscopic slides. Among 439 cysticerci, 234 (53%) had pair rostellar hooks, 88 (20%) with unpair hooks, 60 (14%) only small (outer row) hooks, and 57 (13%) no hooks including 34 hooks were completely dropped and 23 no hooks developed. The number ranged from 10 to 17 pairs for pair hooks and 1 to 29 for unpair ones. The length and width of rostallar hooks on the scolex of cysticerci were usually larger in the pig with longer infection time. Moreover, cysticerci with pair and unpair rostellar hooks had only small hooks and no hooks were present on their scolices. However, cysticerci with only large (inner row) hooks were not found. These findings indicate that the growth and development of small hooks precedes that of the large hooks in the formation of the two-row pattern rostellar hook in Cysticercus cellulosae.

Parasitic infections among the aborigines in Taiwan with special emphasis on Taeniasis asiatica

According to the results obtained by our laboratory and the Department of Parasitology, Taipei Medical College, from 1995 to 1998, the overall infection rate of enterobiasis was 16% (4-29%) among 4,426 primary school students at 64 schools in 13 mountainous districts of 10 counties, and the infection rate of head louse infestation was 12% (3-26%) among 5,121 students. A continuous series of field studies on epidemiology and chemotherapy of taeniasis asiatica have been conducted between 1971 and 1992 among 27,359 aborigines in 88 villages of 14 districts in 10 counties and 3,104 were found to be infected, giving an overall infection rate of 11%. Laboratory studies have been performed on the morphology, intermediate hosts, experimental infection, immunology and molecular biology. Moreover, development of Taiwan Taenia in one of 3 volunteers has been successfully demonstrated since 1988. Moreover, the domestic pig was identified as the intermediate host of Taiwan Taenia as in the classical T. saginata (Poland strain). Most of cysticerci were developed in or on the parenchyma of liver. The results indicated that Taiwan Taenia is different from classical T. saginata. It has been named as T. s. asiatica. Moreover, the classical T. saginata was renamed as T. s. saginata. This paper summarizes findings and reviews those reported by our laboratory. In addition, the clinical manifestations and eating habits of the aborigines are also discussed.

Rodent model for long-term maintenance and development of the viable cysticerci of Taenia saginata asiatica

Although oncospheres of Taenia saginata asiatica can develop into cysticerci in immunodeficiency, immunosuppressed, and normal mice, no detailed information on the development features of these cysticerci from SCID mice is available. In the present study, the tumor-like cyst was found in the subcutaneous tissues of each of 10 SCID mice after 38-244 days inoculation with 39,000 oncospheres of T. s. asiatica. These cysts weighed 2.0-9.6 gm and were 1.5-4.3 cm in diameter. The number of cysticerci were collected from these cysts ranged from 125 to 1,794 and the cysticercus recovery rate from 0.3% to 4.6%. All cysticerci were viable with a diameter of 1-6 mm and 9 abnormal ones each with 2 evaginated protoscoleces were also found. The mean length and width of scolex, protoscolex, and bladder were 477 x 558, 756 x 727, and 1,586 x 1,615 microns, respectively. The diameters of suckers and rostellum were 220 microns and 70 microns, respectively. All cysticerci had two rows of rostellar hooks. These findings suggest that the SCID mouse model can be employed as a tool for long-term maintenance of the biological materials for advanced studies of immunodiagnosis, vaccine development, and evaluation of cestocidal drugs which would be most benefit for the good health of the livestocks.

Capillaria hepatica: a spurious case with a brief review

A 12-year-old Bunun aboriginal school student in Sanmin District Kaohsiung County, Southern Taiwan, was found to have Capillaria hepatica eggs in the feces during a survey on intestinal parasitic infection in 1997. Moreover, this student was also infected with Trichuris trichiura and Ascaris lumbricoides. The C. hepatica eggs were light yellowish-brown in color, 54 (40-60) microns in length and 29 (25-35) microns in width with a 3 (3-4) microns thick shell and two colorless egg plugs 7 (5-9) x 6 (5-8) microns. This is the eighth case of human spurious C. hepatica infection in Taiwan. In addition to the reporting of this case, the genuine and spurious infections of C. hepatica in humans as well as its infection in rats around the world are briefly reviewed.

Sexual development of Taenia solium in hamsters from rodent-derived cysticerci

In order to determine whether Taenia solium can be maintained in the laboratory using rodents as definitive hosts, six nude rats, 20 immunosuppressed Mongolian gerbils and 20 immunosuppressed Syrian hamsters were each inoculated through a stomach tube with three cysticerci recovered from SCID mice. No adult worms of T. solium were found in the intestinal tract of any of these 46 rodents. In addition, five immunosuppressed Syrian hamsters were fed with the same number of cysticerci enclosed in rodent muscles from SCID mice. Two of these hamsters were found to be infected 40 days post-infection, each harbouring a sexually developed worm in the intestinal tract. Although no eggs were produced, prepatent infections may be possible if a longer time was allowed for worm development. Moreover, the maintenance of the life cycle of T. solium in the laboratory using the rodent model can be established.

Oncospheres of Taenia solium and T. saginata asiatica develop into metacestodes in normal and immunosuppressed mice

Normal and immunosuppressed mice were infected with oncospheres of Taenia saginata asiatica and T. solium. Although normal ICR mice were not susceptible to these two parasites, cysticerci were recovered from the immunosuppressed ones following venous injection. For T. s. asiatica, immunosuppressed ICR mice had an infection rate of 12.5% and six cysticerci of this parasite were recovered from three males. After injection of T. solium oncospheres, a high infection rate of 57% was obtained and 23 cysticerci were collected from 13 male immunosuppressed ICR mice. The immunosuppressed C57 mice had the highest infection rate (100%) and cysticercus recovery rate (2.4%) for T. solium. The infection rate and cysticercus recovery rate in six normal C57 mice were 40% and 3% respectively. The immunosuppressed ICR, Balb/c and C3H mice were also susceptible to T. s. asiatica.

Prevalence and treatment of Pediculus capitis infestation among aboriginal school children in northern Taiwan

In the present study, pediculosis was investigated among a total of 2,725 children from 35 primary schools in Hsiulin District of Hualien County, Jenai District of Nantou County, Wulai District of Taipei County, Chienshih District of Hsinchu County, Fushing District of Taoyuan County, and Nanao District of Ilan County. The overall infestation rate was 12.8%. The rates by districts were 19.7%, 17.3%, 16.7%, 15.1%, 7.9%, and 3.0%, respectively. The pediculicides including Nix (permethrin 1%) 56 gm/tube, Para aerosol (bioallethrin 0.66%) 90 gm/tube, and Perioderm (malathion 1%) cream shampoo 40 gm/tube were used to treat the head louse infestation in 83, 91, and 103 children; the cure rates were 97.3%, 94.1%, and 93.4%, respectively. No significant differences were found in these rates. The reactions were slight and transitory. A total of 636 lice was collected from the hair using fine-toothed combs before treatment and from the used towels after treatment of children in Wulai, Chienshih, Hsiulin, and Jenai Districts. Each child was found infested with a mean of 7.7 lice. The mean intensity of infestation was highest in Jenai (9.3) and Chienshih (8.7) came next. Wulai (3.7) and Hsiulin (3.6) had lower intensities.

Review of enterobiasis in Taiwan and offshore islands

From 1995 to 1997, we carried out extensive surveys of Enterobius vermicularis infection among school children in Taiwan and offshore islands. Among 6,315 children at 80 schools in 21 towns and districts of 8 counties tested, an overall infection rate was 11%. The pre-school children had the highest rate of 14%. These findings indicate that pinworm infection remains highly prevalent in Taiwan and offshore islands. Moreover, in this paper, the results from the studies conducted by parasitologists of Taiwan in the past 43 (1955-1997) years were reviewed. This information included epidemiology, diagnosis, chemotherapy, and control methods, may provide some useful suggestions on the prevention of pinworm infection specialists and agencies concerned with the control of this disease.

Egg production capacity of Paragonimus pulmonalis in cats

In the present study, each of 43 cats was fed with a single metacercaria of Paragonimus pulmonalis and 2 cats (controls) with 2 metacercariae. They were killed 22-372 days postinfection. In the test group, 18 (41.9%) cats were infected, as well as the 2 cats in the control group. Among the 18 worms recovered from the test group, 9 found in the lungs were mature, whereas 5 mature and 4 immature worms were in the pleural cavity. Most eggs from worms encased in a cyst were passed in the feces. However, eggs from worms in the pleural cavity were only found on the lung surface and pleural cavity. Mature worms in cysts seemed to exhibit higher egg production capacity than those in the pleural cavity. Paired mature worms from a cyst laid more eggs than a single encysted mature worm in vitro at room temperature.

Annual economic loss caused by Taenia saginata asiatica taeniasis in three endemic areas of east Asia

The Taenia saginata-like tapeworm in East Asia has been designed as a separate subspecies of T. saginata. It was named as T. saginata asiatica and the classical T. saginata as T. saginata saginata. In the course of conducting experimental infections and morphological studies, a large number of adult worms of T. saginata asiatica was collected. It is possible to estimate the annual economic loss caused by this infection, since the worm load and the weight of worm habored by each infected person were determined from the collection. In the mountainous areas of Taiwan, the infection rate of T. saginata asiatica taeniasis was 11.0%, the worm load was 1.6 worms/case, and the average weight of an adult worm was 20.5 g. The annual economic loss was estimated to be US$ 11,327,423. On Cheju Island of Korea, the infection rate was 6.0%, the worm load was 2 worms/case, and the average weight of an adult worm was 19.3 g. The annual economic loss was estimated to be US$ 13,641,021. On Samosir Island of Indonesia, the infection rate was 21%, the worm load was 1.8 worms/case, and the average weight of an adult worm was 22 g. The annual economic loss was estimated to be US$ 2,425,500. These figures indicate that taeniasis is not only a significant public health problem but also an important economic problem in East Asia.

Taenia saginata asiatica: epidemiology, infection, immunological and molecular studies

The taeniasis in East Asia has a special epidemiological pattern: people eat meat and/or viscera of pigs and acquire infection of Taenia saginata-like tapeworms. However, cysticercosis is more often found in pigs than cattles. In order to elucidate the taxonomic status of this parasite, we have conducted extensive field surveys, experimental infections, and morphological as well as immunological studies since 1981. After obtaining sufficient information from our studies, we finally came to the conclusion that the T. saginata-like tapeworm in Asia is a new subspecies of T. saginata and was named as T. saginata asiatica. The classical T. saginata was renamed as T. saginata saginata. In this paper, we provide the history of T. s. asiatica in Asia.

Viability of metacercariae of Clonorchis sinensis in frozen or salted freshwater fish

Metacercariae of Clonorchis sinensis were collected from freshwater fish (Pseudorasbora parva) after storage in a freezer at -12 degrees C for 10-20 days, in a freezer at -20 degrees for 3-7 days, or treating with heavy salt (fish/salt = 10 gm/3 gm) at 26 degrees for 5-15 days. The metacercariae from the frozen fish were inoculated into 30 rats and eight rabbits, and those from the salted fish into 33 rats. Metacercariae from freshwater fish stored at -12 degrees for 10-18 days or -20 degrees for 3-7 remained viable and infective. Moreover, those kept at the heavy salt concentration for 5-7 days remained viable and infective. These findings indicate that freezing or storing infected freshwater fish in heavy salt may not be effective in the prevention of clonorchiasis. However, it appears that refrigeration, or keeping the fish in salt for longer periods, may be suitable for prevention of the infection.

Survival of Taenia solium cysticerci in carcasses of pigs kept at 4 C

In the present study, the survival of cysticerci of Taenia solium in carcasses of 1 Small-Ear-Miniature and 2 Landrace Small-Ear-Miniature pigs kept in a refrigerator at 4 C was determined. The viability of the cysticerci was determined by observing evagination and active movement of the scolex under a fluorescent light after digestion in pig bile. Although no viable cysticerci were found after day 30, 58.8% cysticerci survived between day 26 and day 30. Moreover, more than 80% of the cysticerci were viable between day 1 and day 25. These findings indicate that taeniasis solium can be transmitted through eating raw or undercooked pork or viscera of pigs following refrigeration at 4 C for less than 30 days.

Follow-up immunogenicity of an inactivated hepatitis A virus vaccine in healthy children: results after 5 years

Long-term persistence of hepatitis A virus (HAV) serum antibody in vaccinated children has not been demonstrated in previous studies. To study the long-term immunogenicity to HAV vaccine, three doses of strain HM 175 HAV vaccine with 360 enzyme-linked immunosorbent assay units were administered to 107 children, aged from 1.0 to 6.8 years, at 0, 1, and 6 months. The administration of one vaccine dose induced seropositivity (anti-HAV titer > or = 20 mIU ml-1) in 95% of all vaccinees at month 1. All subjects remained seropositive until month 6. The titers of HAV antibody remained above 20 mIU ml-1 in all subjects followed up to 60 months. The geometric mean titer (GMT) reached its peak (3802 mIU ml-1) at month 7, i.e. 1 month after the booster dose, and then declined until the end of follow-up at month 60 (661 mIU ml-1). A trend of higher GMT in female subjects persisted up to month 60. The changes of the GMT over time were best described by the regression equation: log (GMT) = 3.26-0.08 x (age in years) (r = -0.95, P = 0.014). According to this equation, the geometric mean concentration would reach 20 mIU ml-1 at around 24.5 years after the beginning of vaccination. In conclusion, those who completed the recommended three-dose inactivated HAV vaccination series remained seroprotective for at least 5 years. Theoretically, such a vaccination program can provide a protective period of over 20 years in children. This paper may be the first to describe at least 5-year immunogenicity of inactivated HAV vaccination in healthy children.

A comparative study on egg hatching methods and oncosphere viability determination for Taenia solium eggs

The efficiencies of an enzyme method and the sodium hypochlorite method in hatching eggs of Taenia solium (Henan strain) were compared. The viability of the hatched oncospheres was determined by staining with trypan blue. For the former method, the hatching rate and viability percentage were 85.7% and 79.7%, respectively. The corresponding figures for the latter method were 97.9% and 86.7%, respectively. These findings indicate that the sodium hypochlorite method is a simple, efficient and practical method for hatching eggs of Taenia solium.

Sociocultural factors and local customs related to taeniasis in east Asia

Taeniasis is an important medical and economic problem in many countries in East Asia. According to our estimation, there is an annual loss of US$18,673,495, US$13,641,021, and US$2,425,500 due to taeniasis in the mountainous areas of Taiwan, Cheju Island of Korea, and Samosir Island of Indonesia, respectively. Although taeniasis and cysticercosis due to Taenia solium have been reported, T. saginata asiatica is the dominate species in part of the world, especially in the mountainous and remote areas where the inhabitants are fond of eating raw or undercooked meat and/or viscera of domestic or wild animals. Therefore, sociocultural factors and local customs are the determinants in the transmission of taeniasis. In this paper, local customs and sociocultural factors including local dishes, accidental infection during dish preparation, and treatment for anaemia of children in the countries of East Asia were reviewed.

Vaccination trials against Taiwan Taenia eggs in pigs injected with frozen oncospheres of Taiwan Taenia, Korea Taenia, T. saginata or T. solium

When Small-Ear-Miniature pigs subcutaneously injected once with frozen oncospheres of Taiwan Taenia, Korea Taenia, T. saginata or T. solium emulsified with Freund's complete adjuvant (1.6 x 10(4)/0.4 ml) were challenged orally with 1.6 x 10(4) viable eggs of Taiwan Taenia 41 days later, they all showed strong resistance compared with pigs vaccinated with T. solium. Most pigs (5/8) of the former 3 groups harboured no cysticerci. The number of cysticerci was 5.5 +/- 9.1 (mean +/- S.D.), whereas pigs of the T. solium group and control group harboured 160 +/- 30.1 and 661 +/- 637.2 cysticerci, respectively. All cysticerci recovered from vaccinated pigs and most cysticerci in control pigs were degenerated or calcified at 36-55 days after oral egg challenge. These results strongly suggest that oncospheres of Taiwan Taenia and Korea Taenia are very similar to T. saginata in their immunogenicity in pigs.

In vitro hatched oncospheres of Asian Taenia from Korea and Taiwan develop into cysticerci in the peritoneal cavity of female scid (severe combined immunodeficiency) mice

In vitro hatched (but not activated) oncospheres of Asian Taenia obtained in Korea and Taiwan, prepared by the sodium hypochlorite method, rinsed with sterile PBS several times and adjusted to 5 x 10(4)/0.5 ml PBS, were injected intraperitoneally or subcutaneously into male or female scid mice of 3 different strains. When these scid mice were sacrificed 4 months later, the females harboured fully developed cysticerci either in the peritoneal cavity or under the back skin, whereas males did not. All cysticerci from the peritoneal cavity were easily recovered by rinsing the abdomen with PBS. Although most cysticerci recovered from pig liver usually become calcified within 1-2 months, in female scid mice they all increased in size and were viable. Intraperitoneal (i.p.) injection of in vitro hatched oncospheres is recommended for easier recovery of Asian Taenia metacestodes in laboratory animals.

Magnetic resonance imaging in symptomatic/cryptogenic partial epilepsies of infants and children

In order to identify the brain lesions of symptomatic/cryptogenic partial epilepsies (S/CPEs) in infants and children, magnetic resonance imaging (MRI) studies, thorough encephalographic (EEGic) studies, and detailed clinical and neurologic evaluations were obtained in 300 infants and children who were diagnosed to have S/CPEs with onset before the age of 13 years during the past 7 years. The overall detection rate of brain lesions by MRI was 41.7% (125/300). Congenital malformations (18 cases), vascular malformations (9 cases), neurocutaneous syndromes (13 cases), and space-taking lesions (20 cases) constitute a large percentage of SPEs in infants and children. A variety of insults such as infection, ischemia, hemorrhage, trauma and metabolic disorders can result in destructive parenchymal loss lesions including porencephaly, focal atrophy, hemiatrophy, and diffuse brain atrophy (20 cases). Major etiologic factors leading to infarction, encephalomalacia, leukomalacia, included trauma, hvpoxicischemic encephalopathy (HIE), systemic lupus erythematosus (SLE), encephalitis, vasculitis, venous thrombosis, vasculopathies, and heart problems (22 cases). Mesial temporal sclerosis (MTS) could be evidenced in around 20% (18/95) of cases with temporal lobe epilepsy (TLE), which was strongly associated with past histories of febrile seizures and encephalitis complicated by status epileptics. However, cases with porencephaly, global atrophy or delayed myelination of unilateral temporal lobe on MRI were more related to HIE. With the advent of neuroimaging techniques, particularly MRI, a wide variety of underlying pathology can be detected as a cause of symptomatic partial epilepsies in pediatric patients. The occurrence of S/CPE indicates the presence of localized brain dysfunction, and many of the causes are potentially treatable. An orderly and thorough clinical and laboratory investigations, as well as neuroimaging studies should be made to diagnose and treat any underlying conditions.

Urine lipids in patients with a history of filariasis

The presence of lipids in postprandial urine was assessed in 116 patients with a history of filariasis and 70 normal individuals using a biochemical autoanalyzer. Urinary triglycerides (TGs) ranging from 10 to 1955 mg/dl were detected in 13 individuals with a history of chyluria, including 3 with TG levels ranging from 233 to 1955 mg/dl and cholesterol levels of 6-35 mg/dl. Three patients who had a filarial history but without chyluria were also found to have urinary TGs (13-15 mg/dl) without detectable cholesterol. Neither TGs nor cholesterol were detected in the urine of normal individuals. Fluctuations in postprandial urine lipid contents were measured by time course determinations of urinary TG and cholesterol in 17 patients with filariasis and a history of chyluria, 16 patients with filariasis and hydrocele and 16 normal individuals. The level of urine lipid excretion was found to increase within 1-4 h postprandially, with urinary TG levels ranging between 7.8 and 1284 mg/h in eight patients and urinary cholesterol levels between 1.2 and 138 mg/h in seven patients with a history of chyluria. To evaluate the origin of the urine lipids in hematochyluria, fish oil containing 360 mg eicosapentaenoic acid (EPA) and 240 mg docosahexaenoic acid (DHA) was prescribed to a patient with hematochyluria. The excretion of EPA and DHA in urine was increased postprandially in the patient, similar to the elevation of urinary TG and cholesterol. The profile of fatty acids from urine samples showed it was of dietary origin. Our results suggest that postprandial urine lipids, especially TG, might be used as markers for the clinical evaluation of chyluria.

Human Taenia eggs develop into cysticerci in scid mice

The intermediate hosts for Taenia saginata and T. solium are cattle and pigs (and humans for the latter), respectively. In vitro-hatched (but not activated) oncospheres of both Asian Taenia (T. saginata asiatica, a new subspecies of T. saginata or T. asiatica, a new species) and T. solium injected subcutaneously into the backs of mice with severe combined immunodeficiency (scid) developed into fully matured cysticerci. Five-month-old metacestodes of Asian Taenia had no hooklets and were bigger in size than those previously reported and similar to those of T. saginata. Their morphology suggested that the cysticerci were more advanced than those in the intermediate host animals. It is suggested that scid mice are valuable experimental animal models for studying human taeniid cestode infections.

Rigid bronchoscopy and jet ventilation in an extremely low birthweight infant

Until recently, rigid bronchoscopy was considered too risky for premature infants. We report a 658 g infant with life-threatening mediastinal shift due to right pulmonary atelectasis. Rigid bronchoscopy revealed tenacious mucous plugs in the right main bronchus. The collapsed lung was successfully reinflated after bronchial lavage with a rigid bronchoscope, with the help of intermittent high-frequency jet ventilation (HFJV). The infant's mediastinal shift was reversed and the vital signs became stable. In our experience, rigid bronchoscopy combined with HFJV is a valuable diagnostic and therapeutic procedure for very small premature infants.

Ectopic locations of Taenia saginata asiatica cysticerci in the abdominal cavity of domestic pig and monkey

Eleven Small-Ear-Miniature pigs, 1 Landrace Small-Ear-Miniature pig, and 1 monkey (Macaca cyclopis) were infected experimentally with eggs of Taenia saginata asiatica. They were found to harbor cysticerci on the liver surface, each with a thin, whitish fiber connecting to another location in the same lobe, or to other lobes of the liver; some were also connected individually to the diaphragm, abdominal muscles, and gall bladder with a short, thin fiber. Moreover, they also harbored extrahepatic cysticerci. Most of these were observed on the omentum and in the peritoneal cavity, except for some suspended individually in the abdominal cavity by a long, thin, whitish fiber. The origin of the extrahepatic cysticerci and whitish fibers is probably from the surface of the liver of the host.

Severe myoclonic epilepsy in infancy: evolution of electroencephalographic and clinical features

Since 1987, we have diagnosed 10 patients, 4 males and 6 females, aged 2-11 years at the last evaluation, who all met the following criteria of severe myoclonic epilepsy in infancy (SMEI): generalized or unilateral long-lasting febrile clonic seizures in the first year of life; the subsequent appearance of myoclonic seizures and other types of seizure (partial seizures, atypical absences and convulsive status epilepticus); and neuropsychological deterioration for a certain period. Family histories of epilepsy and febrile seizures could be traced in 1 and 3 cases, respectively. None of them had previous personal history of brain insult. Electroencephalographic (EEGic) recordings in febrile seizure stage were normal; and continuous prophylaxis with phenobarbital failed to prevent the recurrence of febrile seizures. EEG studies in myoclonic stage showed generalized spike-and-waves, polyspike-and-waves, focal abnormalities and/or photosensitivity. The seizures were highly resistant to antiepileptic drugs. Our experiences suggested that comedication of valproic acid, clonazepam and carbamazepine may be most effective in treatment of the diverse seizures including myoclonic seizures, myoclonic-tonic-clonic seizures, atypical absences and partial seizures. Myoclonic seizures and atypical absences diminished in parallel to a clear-cut decrease in generalized abnormalities on EEG in 4 cases aged more than 7 years. However, the partial seizures, secondarily generalized seizures and status epilepticus were still present. Further investigations should aim to identify the underlying etiology and to search more effective treatment.

Impaired immune function in a premature infant with zinc deficiency after total parenteral nutrition

The report describes a premature infant with necrotizing enterocolitis who developed symptoms of zinc (Zn) deficiency after three to four weeks of total parenteral nutrition (TPN). Clinical presentations included characteristic skin rash, alopecia, retarded growth, generalized edema and decreased serum alkaline phosphatase (ALP). Immune function studies revealed impaired neutrophil adhesion and mitogen-induced lymphoproliferation, whereas phagocytosis, chemotaxis and lymphocyte subsets remained normal. A high dose of elemental Zn (2.5 mg/kg/day), administered orally, improved the clinical symptoms and restored the immune function. In patients with Zn deficiency, impaired neutrophil adhesion and lymphocyte function may contribute to immunodeficiency which can be reversed with adequate Zn supplementation.

Experimental studies on the pathway for migration and the development of Taiwan Taenia in domestic pigs

The pig is the most favorable experimental intermediate host of Taiwan Taenia. Cysticerci in infected pigs are located in the liver except for a few extrahepatic ones. The present study was designed to investigate the pathway of migration of the oncospheres of Taiwan Taenia in the pig. In the first group, each of 5 Small-Ear-Miniature (SEM) and one Landrace-Small-Ear-Miniature (L-SEM) pigs were injected with 5000 hatched oncospheres into the ear vein. Three SEM and one L-SEM pigs were found to harbor 88 degenerated or calcified cysticerci only in the liver 51-81 days after injection. In the second group, each of 3 L-SEM pigs were injected with 5000 hatched oncospheres into the jugular vein. One of the 3 pigs was found to have 5 cysticerci (2 mature and 3 degenerated or calcified) only in the liver at 89 days post-injection. In the third group, each of 4 SEM, three L-SEM, and 3 L-SEM pigs were injected with 10,000, 10,000, and 5000 hatched oncospheres, respectively, directly into the portal vein after surgical opening of the abdominal cavity. All 10 pigs were found to be infected with a total of 1088 cysticerci (44 mature and 1044 degenerated or calcified) only in the liver 23-62 days after injection. Although the sites of injection in these three groups were different, the liver was the only final location of the cysticerci. These findings give strong evidence that the oncospheres migrate to the liver through the venous circulation and develop in this organ.

Morphological description of Taenia saginata asiatica (Cyclophyllidea: Taeniidae) from man in Asia

In order to clarify the taxonomic status of the Taenia saginata-like tapeworm in East Asia, the morphological characteristics of the adult and cysticercus of classical T. saginata (American, Swiss and Poland strains) and the Taiwan Taenia were compared in the present study. The morphologic characteristics of these two parasites are very similar. The protoscolex of cysticercus of the Taiwan Taenia has a sunken rostellum while that of classical T. saginata has only an apical pit. In addition, the rostellum of the Taiwan Taenia cysticercus is usually surrounded by two rows of rudimentary hooklets. However, this structure is rarely found in classical T. saginata. Based on the results of molecular studies and morphological characteristics, the T. saginata-like tapeworm in East Asia represents a subspecies of T. saginata, named T. saginata asiatica.

Follow-up investigations on clinical manifestations after filariasis eradication by diethylcarbamazine medicated common salt on Kinmen (Quemoy) Islands, Republic of China

From May to December 1993, a house-by-house survey was conducted on the changes in clinical manifestations of filariasis among 814 pre-control mf carriers in 88 villages of five towns/districts on Kinmen Islands. Four hundred and sixteen (51%) pre-control mf carriers were examined physically with history taking. The rates of disappearance, improvement, no change, aggravation, and new occurrence were 72% (229), 6% (26), 14% (59), 6% (24) and 2% (8), respectively. The rates of disappearance and improvement were higher for the acute than for the chronic manifestations. However, these rates were also high for hydrocele and chyluria. These findings indicate that the acute manifestations disappear or greatly improve after filariasis eradication by a low dose of DEC medicated salt for a period of 6 months. However, the chronic ones remain unchanged or even aggravated to become one of the more important public health problems.

Hypersensitivity to mosquito bite: a case report

Severe hypersensitivity to mosquito bites is very rare. A 18-year-old girl student has had multiple hemorrhagic bullae with atrophic scars on both limbs and left side of the face due to mosquito bites for 16 years. When she was seven years old, she noticed a severe local reaction with bloody bullae formation, chills, and fever several hours after the mosquito bite. The bullae developed into ulcers which finally became scars. This patient was confirmed to be hypersensitive to mosquito bites by the mosquito bite test. This case is the first record of mosquito allergy in Taiwan.

Review of taeniasis in Asia

Although Asian Taenia is closely related to T. saginata, it is a genetically distinct entity and can be distinguished from the classical T. saginata. Man is the only definite host of this parasite. The domestic pig and wild boar in Taiwan as well as domestic pig in Korea have been determined to be the natural intermediate hosts. Moreover, the pig has been demonstrated to be the most favorable experimental intermediate host. The cysticerci are situated mainly in the liver. They are smaller than T. saginata cysticerci and have a shorter developmental period of four weeks. The scolex of Asian Taenia cysticercus is often armed with two rows of hooklets. The adult worm of Asian Taenia is shorter and has less number of segments than the classical T. saginata. Recently, results of polymerase chain reaction studies indicate that the Asian Taenia is much more closely related to T. saginata than other taeniid species. Therefore, it is appropriate to designate Asian Taenia as a new subspecies of Taenia saginata asiatica. People in the Asian-Pacific region acquired the infection by eating raw or undercooked meat and/or viscera of pigs. Human experimental infections have succeeded in confirming the life cycle of Asian Taenia and the transmission pathway of the infection. In addition, multiple infection occurs very often and the infection has a family pattern. "Discharge of proglottids" is the most important clinical manifestation which is also useful in the diagnosis. Praziquantel is the drug of choice. The infection of Asian Taenia can be prevented by avoiding to eat raw or undercooked meat and viscera of pigs in the endemic regions.

The minimum effective dose of praziquantel in treatment of Hymenolepis diminuta in rats

To determine the minimum effective dose of praziquantel against Hymenolepis diminuta in rats, 5.0 mg/kg, 2.5 mg/kg, 1.0 mg/kg, 0.5 mg/kg, 0.1 mg/kg, or 0.05 mg/kg praziquantel were given to each of five experimentally infected rats in six groups. Faecal samples from each rat were examined on ten consecutive days following treatment. The rats were killed and examined for worms on day 10. Based on the results of faecal examination and autopsy, the minimum effective dose of praziquantel against Hymenolepis diminuta in rats was determined to be 0.5 mg/kg.

Determination of the earliest appearance and peak count of microfilariae of Wuchereria bancrofti and Brugia malayi after taking a single dose of diethylcarbamazine at noon

Six nocturnal microfilarial carriers (three with Wuchereria bancrofti and three with Brugia malayi) from mainland China were selected to determine the earliest appearance and peak count of microfilariae (mf) administration of DEC at noon. Before diethylcarbamazine (DEC) administration, blood samples of 60 microliters were obtained by finger-prick at 2 h intervals for 24 h. A blood sample was then taken just before each carrier intaking 100 mg, 150 mg or 200 mg of DEC orally at noon. After drug administration, blood samples were obtained at 45 and 60 sec and at 2, 3, 4, 5, 10, 15, 20, 25, 30, 40, 50, 60, 90 and 120 min. Samples were then taken at 2 h intervals for the next 2 h and at 6 h intervals for the next 7 days. Both W. bancrofti and B. malayi showed typical nocturnal periodicity. One mf was first detected in the peripheral blood 45 sec in a mf. carrier. The mf peak counts were found 1-40 min after DEC administration at noon. The nocturnal cycle was distributed during the first two days after DEC administration. It became regular with a much lower peak count by the third day after administration. The results of the present study indicate that the provocative effect of DEC on the mf is very fast; the first appearance in the peripheral blood vessels could be under 45 sec.

Experimental infection of an isolate of Taenia solium from Hainan in domestic animals

The present study was designed to determine the susceptibility of domestic animals to an isolate of Taenia solium from Hainan Province, People's Republic of China. A total of 162 cysticerci were recovered from two pigs and 21 from two dogs after experimental inoculation. Cats, goats and a calf were not susceptible to T. solium. Cysticerci were recovered mainly from muscles of the pigs and all were alive. The remainder were in the liver and only one was alive. In the dog, all cysticerci were recovered from the muscles and all were alive.

Encapsulated egg deposition pattern of Schistosoma japonicum in the peritoneal cavity of mice

Thirty-four albino mice were each exposed to 20 cercariae of Schistosoma japonicum by the intraperitoneal or percutaneous route and killed after 60-127 days. The peritoneal cavity of each mouse was flushed and worms in the portal vein system were perfused with citrated saline. After sedimentation, washings were examined microscopically. Mature worms were only found in the portal vein system. The worm recovery rate was much higher by percutaneous infection (61.2%) than by intraperitoneal (37.1%). The encapsulated egg granulomas were observed either in the peritoneal cavity or on the intestinal wall; the mean number of encapsulated egg granulomas was also higher in the former (1.6) than in the latter (0.6). The average number of eggs per granuloma was very similar by both routes (10.7 and 11.4). The mean size of encapsulated egg granulomas (529 microns) was increased correspondingly with the number of eggs (range 181-985 microns). The percentage of viable eggs within the granulomas in the peritoneal cavity (77%) was much higher than those on the intestinal wall (18%). Encapsulated egg granulomas were usually ovoid although some had an irregular shape.