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As part of the international joint projects working towards the control of taeniosis/cysticercosis in Asia Pacific, epidemiological studies on Taenia solium cysticercosis have been carried out in high-incidence populations, such as minority groups in Thailand. To assess the epidemiology of cysticercotic infections in pigs in the hill-tribe minority villages (Karen) in Tak province, Thailand, we conducted serological screening and necropsies. The patterns of antibody response to T. solium antigens were then investigated using immunoblot assays. Of the 188 pig serum samples tested for antibody responses to partially purified low-molecular-weight antigens of T. solium cyst fluid, positive responses were detected in 37 samples (19.7%). Based on these results, 16 pigs (10 seropositive and 6 seronegative) were necropsied for investigation of cysticerci and intestinal parasites. All seropositive pigs were coinfected with both T. solium and Taenia hydatigena cysticerci, except one, which was infected with T. hydatigena alone. Three of the six seronegative pigs were confirmed to be infected with T. hydatigena. Pigs infected with T. solium showed much stronger antibody responses than those infected with T. hydatigena. Our results demonstrate the co-occurrence of two swine cysticercoses due to T. solium and T. hydatigena in the studied areas. This study also reveals the importance of direct confirmation of the presence of cysticerci by necropsy after serological screening. In addition to the prevalence of swine cysticercosis in these endemic areas, our findings also reveal potential implications for the development of serological diagnostic assays for swine cysticercosis.

This review presents the historical and current situation of echinococcoses in Mongolia. Since the collapse of the Soviet Union in 1991, Mongolia's health surveillance infrastructure has been very poor, especially as it pertains to chronic diseases, including neglected zoonotic diseases (NZDs). Although there is anecdotal evidence of people dying from hepatic disease due to infection with the larval stage of Echinococcus spp., there are very few published reports. All confirmed cases of echinococcoses in Mongolia are from hospitals located in the capital city of Ulaanbaatar. Cases of cystic echinococcosis (CE), caused by either Echinococcus granulosus sensu stricto or Echinococcus canadensis are believed to be relatively common throughout Mongolia. In contrast, cases of alveolar echinococcosis (AE), caused by Echinococcus multilocularis, are believed to be rare. Recent wild-animal surveys have revealed that wolves (Canis lupus) are the major definitive hosts of E. canadensis, whereas both wolves and red foxes (Vulpes vulpes) are the primary definitive hosts of E. multilocularis. Although wild-animal surveys have begun to elucidate the transmission of Echinococcus spp. in Mongolia, there have yet to be large-scale studies conducted in domestic dogs and livestock. Therefore, further epidemiological studies, in addition to education-based control campaigns, are needed to help combat this NZD.

Bovine cysticercosis causing damage to the beef industry is closely linked to human taeniasis due to Taenia saginata. In African countries, Taenia spp. from wildlife are also involved as possible sources of infections in livestock. To identify the aetiological agents of bovine cysticercosis in Ethiopia, cysticerci were collected from 41 cattle slaughtered in the eastern and central areas during 2010–2012. A single cysticercus per animal was subjected to the polymerase chain reaction (PCR)-based DNA sequencing of mitochondrial cytochrome c oxidase subunit 1 gene, and the resultant sequence was compared with those of members of the genus Taenia. Although 38 out of 41 cysticerci (92.7%) were identified as T. saginata, three samples (7.3%) showed the hitherto unknown sequences of Taenia sp., which is distantly related to Taenia solium, Taenia arctos and Taenia ovis. Old literatures suggest it to be Taenia hyaenae, but morphological identification of species could not be completed by observing only the larval samples.

Serology (ELISA and immunoblot) using native glycoproteins, affinity purified glycoproteins, and a recombinant antigen is known to be highly specific toTaenia soliumcysticercosis in humans and pigs. These techniques were applied for dogs in the highly endemic area of cysticercosis in Papua (Irian Jaya), Indonesia. Analysis of dog sera by both ELISA and immunoblot revealed 7 of 64 dogs were highly positive. Examination of two sero-positive dogs revealed cysticerci ofT. soliumin the brain and heart of these dogs. Mitochondrial DNA analysis confirmed that they were the same asT. soliumpreviously confirmed from pigs and biopsies from local people from Irian Jaya. It is suggested that the life cycle ofT. soliummay be completed not only between humans and pigs but also between humans and dogs.

Experimental infection of larval Echinococcus multilocularis in the rodent brain was attempted to establish a murine model for cerebral alveolar echinococcosis. Balb/c mice and jirds were injected intracranially with 10% of a homogenated hydatid cyst mass. Small cystic larvae were observed macroscopically in the cranial cavity 1, 2 and 5 months post-infection in both mice and jirds. Some larval cysts from both rodents contained mature or immature protoscoleces. In mice, the laminated layer was found in the lateral ventricle 2 months post-infection but without protoscoleces. At five months post-infection, larger larval cysts were found in the cranial cavity of a mouse, which also demonstrated partial palsy of the legs. A laminated layer with mature protoscoleces was observed in the third ventricle and the mouse also harboured, in the left lung, a larval cyst containing protoscoleces surrounded by lymphocytes. Jirds were also found to be infected with metacestodes in the cranial cavity, but neither unusual behaviour nor establishment of cysts inside the brain was observed in jirds during the course of infection.

A case of cystic echinococcosis (CE) in a domestic cat is described from Saint Petersburg, Russia. Ultrasonography showed numerous cysts with hyperechoic walls and anechoic contents within the cat's abdominal cavity. Molecular identification based on mitochondrial DNA genes indicated that the causative agent was Echinococcus granulosus sensu stricto (G1 strain). This is the first report of CE in a cat caused by E. granulosus sensu stricto with molecular confirmation.

The assay system for antibody responses against Em2, the most specific antigen for serodiagnosis of alveolar echinococcosis (AE), has been established by enzyme-linked immunosorbent assay (ELISA) but not by Western blot assay, since Em2 antigen is not protein but carbohydrate in nature. Recently we reported that previously undescribed protein epitopes, designated Em18 and Em16 due to their molecular weights, were good serologic markers for AE by Western blot analysis. It has been shown that Em18 and Em16 are the only two epitopes recognized by commercially available weak positive (cut off) sera for the Em2plus-ELISA.

A preliminary study to detect human worm carriers of Taenia solium in Papua (Irian Jaya), Indonesia was carried out using stool examinations for the detection of copro-antigens and adult proglottids after chemotherapy, and confirmation by mitochondrial DNA analysis using expelled proglottids and metacestodes developed in NOD/Shi-scid mice from eggs of expelled proglottids. Approximately 8.6% of the local population in Kama (5/58), 1 km from the local capital city centre, Wamena, were confirmed to harbour adult T. solium using these techniques.

Antibody responses against crude antigens and the two (Em18 and Em16) epitopes of Echinococcus mulfilocularis were analysed by Western blotting using sera from the wild vole, Clethrionomys rufocanus bedfordiae (Crb), which were captured in Hokkaido, Japan and found to have been naturally infected with eggs, and compared with those in patients of AHD and mice experimentally infected with protoscoleces of this parasite. Antibody responses in the wild vole were demonstrated most clearly with anti-Crb-IgG antiserum but more faintly with anti-rat-IgG antiserum and poorly with anti-mouse-IgG or anti-human-IgG antisera or Protein G. Although only two serum samples of the wild vole found naturally infected were analysed, antibody responses against Em18 and Em16 in these voles appeared to be similar to those in AHD patients but differed from those in mice.

Rats are known to be relatively resistant to infection withEchinococcus multilocularis. However, when rats are inoculated with the parasite tissues,E. multilocularisproliferates slowly at first but after 6 months the cysts increase in size considerably and contain large numbers of protoscoleces. As rats survive for 18 months or longer, approximately 100 ml of packed protoscoleces can be produced from each rat. A comparison of the antigenicity of the protoscoleces and microvesicles by immunoblot methods showed that both Em18 and Em16 are shared components between both protoscoleces and microvesicles, although the latter have some additional antigenic components. In antigens prepared from protoscoleces, the banding patterns around Em18 were much simpler than those from microvesicles. Therefore, for serodiagnosis ofE. multilocularis, antigens should be carefully prepared from protoscoleces rather than microvesicles from the rat.

The establishment of reliable serological methods for cysticercosis in pigs is important for the surveillance, control and prevention of taeniosis/cysticercosis in humans as well as in pigs to prevent economic loss. Both ELISA and immunoblot using glycoproteins (GPs) purified by a single step of preparative iso-electric focusing, which are highly useful for human cysticercosis, have been applied for a serological study in pigs naturally infected withTaenia solium. All sera from pigs showed similar responses to those in human cysticercosis. Therefore, it is expected that both ELISA and immunoblots using GPs would be useful in differentiating infected pigs from uninfected ones.

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.

Although the normal intermediate hosts of Hymenolepis microstoma are insects, oncospheres invade the intestinal tissue of the definitive hosts, mice, within 30 min after oral egg inoculation.

A comparative study of eosinophil chemotactic factors was carried out using cysticercoids and oncospheres of Hymenolepis nana. Cysticercoids showed twice the chemotactic activity for eosinophils than the oncospheres. Eosinophilia induced by oncospheres and cysticercoids observed in secondary and primary infections, respectively, were discussed from the view point of the immunobiology of this parasite.

Female mice of nine inbred strains (A, AKR, BALB/c, C3H, C57BL/6, C57BL/10, CBA, DBA/1 and DBA/2) and H-2 congenic B10.D2, at 9–10 weeks of age, were infected with larval Echinococcus multilocularis by trans-portal injection of hydatid homogenate. Parasitized livers were histologically examined 9 or 13 weeks after infection. Hydatid development was quite different among mouse strains. Multivesiculation was prominent in C57BL/10, DBA/1, C57BL/6 and BALB/c. Protoscoleces were well developed in DBA/2, AKR, DBA/1 and CBA. H-2 congenic B10.D2, which has the background genes of C57BL/10 except for the H-2d gene of DBA/2, resembled C57BL/10 in prohibiting the development of protoscoleces. These data suggest that the qualitative difference in hydatid development may be regulated by non-H-2 gene(s).

Two Norway rats, Rattus norvegicus, were found to be naturally infected with Echinococcus multilocularis in Japan. One of them was simultaneously infected with at least three different sized metacestodes of Taenia taeniaeformis. These two R. norvegicus rats and another R. norvegicus naturally infected with T. taeniaeformis and Capillaria hepatica were examined to see if they showed any antibody responses against these two cestode parasites with the view to obtaining more information on the importance of rats as the intermediate host for E. multilocularis. These R. norvegicus showed very poor antibody responses against the two cestode species, although the Wistar rats, R. rattus, experimentally infected with a single smaller sized metacestode of T. taeniaeformis showed stronger responses not only against T. taeniaeformis but also against E. multilocularis. Therefore the three R. norvegicus naturally infected with E. multilocularis and/or T. taeniaeformis demonstrated virtually no immune response, at least against these cestodes.

In order to establish a simple means of handling eggs of taeniid cestodes under non-biohazardous conditions, gravid segments of Taenia taeniaeformis were fixed in ethanol or formalin or were frozen. In vitro hatching of oncospheres was carried out by the 0.5% sodium hypochlorite method using eggs isolated from the nonviable and viable segments. No oncospheres hatched from formalized eggs, whereas almost all oncospheres hatched from all other eggs but the number of oncospheres recovered was highly variable. Oncospheres hatched from eggs isolated from frozen segments were highly fragile. The highest figures for in vitro hatching of oncospheres were recorded when eggs isolated either from segments fixed in 70% ethanol or from viable segments were used.

It was determined to examine whether rats injected with non-viable oncospheres of Asian Taenia or Taenia saginata became resistant to challenge infection with eggs of Taenia taeniaeformis, since (a) metacestodes of Asian Taenia and T. taeniaeformis develop in the liver of pigs and rats, respectively, and (b) Asian Taenia and T. saginata have human origins. Rats injected intravenously or subcutaneously with complete Freund's adjuvant with non-viable oncospheres of Asian Taenia showed statistically significant resistance to challenge infection with eggs of T. taeniaeformis, whereas those injected with non-viable oncospheres of T. saginata did not show any resistance.

The usefulness of hatched but non-activated oncospheres as a candidate vaccine was evaluated using a Taenia taeniaeformis/rat system, since preparation of these oncospheres in vitro is known to be very simple. The findings were: (1) rats vaccinated with non-viable oncospheres became completely resistant to challenge infection; (2) intra-venous injection was the most effective to induce complete resistance; (3) a single oncosphere was sufficient to induce complete resistance in infected rats, whereas approximately 50 and 500 non-viable oncospheres were required to evoke strong and complete resistance, respectively, in vaccinated rats. The usefulness of non-viable oncospheres without adjuvant is discussed.

The cestocidal activity of Acacia auriculiformis was evaluated using rats each harbouring a single adult worm of Hymenolepis diminuta. The ethanol extract (300 mg/kg/day) and the saponins (200 mg/kg/day) obtained from the funicles of A. auriculiformis, were administered orally to two groups each of 10 rats, respectively, on day 20 after oral inoculation with a single cysticercoid of H. diminuta. Adult worms were expelled within 5 days from rats treated with the ethanol extract and within 3 days from those treated with saponins. No appreciable side effects were observed in the treated 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 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.

Treatment with praziquantcl at the beginning of the lumen phase ofHymenolepis nanain mice showed conclusively that: (i) the mouse given eggs ofH. nanaproduces two separate immune responses against reinfection, one directed exclusively against the tissue phase of egg challenge (early response), the other against the lumen phase of cysticcrcoid challenge (late response); (ii) a tissue phase of egg inoculation is not necessary for initiating the late response but is necessary to provoke the early response; and (iii)H. nanaexpresses several stage-specific immunogens through its development in the mouse host.

The surface antigens of oncosphere, cysticercoid, adult scolex and adult strobila (other than scolex) of Hymenolepis nana differ critically from one another. When the oncosphere of H. nana undergoes differentiation and development into the mature tapeworm, the infected mouse first produces anti-oncosphere antibody, followed by anti-cysticercoid, anti-adult scolex and finally anti-strobila (other than scolex region) antibodies of IgG, IgM and IgA isotypes as detected by indirect immunofluorescent antibody test. The parasite changed its surface antigens throughout its differentiation and maturation, and all developmental stages were recognized by the infected mouse host. However, there appeared no further changes in surface antigens during aging after maturation. The antibody responses were always delayed compared with the differentiation and maturation of the parasite.