Genome of the fatal tapeworm Sparganum proliferum uncovers mechanisms for cryptic life cycle and aberrant larval proliferation.

The cryptic parasite Sparganum proliferum proliferates in humans and invades tissues and organs. Only scattered cases have been reported, but S. proliferum infection is always fatal. However, S. proliferum's phylogeny and life cycle remain enigmatic. To investigate the phylogenetic relationships between S. proliferum and other cestode species, and to examine the mechanisms underlying pathogenicity, we sequenced the entire genomes of S. proliferum and a closely related non-life-threatening tapeworm Spirometra erinaceieuropaei. Additionally, we performed larvae transcriptome analyses of S. proliferum plerocercoid to identify genes involved in asexual reproduction in the host. The genome sequences confirmed that the S. proliferum has experienced a clearly distinct evolutionary history from S. erinaceieuropaei. Moreover, we found that nonordinal extracellular matrix coordination allows asexual reproduction in the host, and loss of sexual maturity in S. proliferum are responsible for its fatal pathogenicity to humans. Our high-quality reference genome sequences should be valuable for future studies of pseudophyllidean tapeworm biology and parasitism.

Reassessing therapeutic antibodies for neglected and tropical diseases.

In the past two decades there has been a significant expansion in the number of new therapeutic monoclonal antibodies (mAbs) that are approved by regulators. The discovery of these new medicines has been driven primarily by new approaches in inflammatory diseases and oncology, especially in immuno-oncology. Other recent successes have included new antibodies for use in viral diseases, including HIV. The perception of very high costs associated with mAbs has led to the assumption that they play no role in prophylaxis for diseases of poverty. However, improvements in antibody-expression yields and manufacturing processes indicate this is a cost-effective option for providing protection from many types of infection that should be revisited. Recent technology developments also indicate that several months of protection could be achieved with a single dose. Moreover, new methods in B cell sorting now enable the systematic identification of high-quality antibodies from humanized mice, or patients. This Review discusses the potential for passive immunization against schistosomiasis, fungal infections, dengue, and other neglected diseases.

Immunolocalization of the 29 kDa Schistosoma haematobium species-specific antigen: a potential diagnostic marker for urinary schistosomiasis.

BACKGROUND: The 29 kDa Schistosoma haematobium species-specific antigen (ShSSA) is of remarkable interest in the diagnosis of urinary schistosomiasis although it had not been fully characterized. METHOD: To determine the biological importance of ShSSA in S. haematobium and pathogenesis of the disease, we immunolocalized ShSSA in schistosome eggshells, miracidia and adult worm sections using indirect fluorescent antibody test (IFAT). RESULTS: ShSSA was strongly immunolocalized in the schistosome eggshells, selective regions of the miracidia body and walls of internal organs such as oviduct, ovary, vitelline duct and gut of the adult worm. CONCLUSION: The strong immunolocalization of ShSSA in schistosome eggshells and adult worm internal organs suggests that the antigens involved in the pathogenesis of urinary schistosomiasis could have originated from the eggs and adult worms of the parasite. The findings also indicate that ShSSA may play a mechanical protective role in the survival of the parasite.

Paragonimiasis prevalences in Saraburi Province, Thailand, measured 20 years apart.

Saraburi Province, Central Thailand has been a paragonimiasis-endemic area since 1956. This study compared the prevalences of human paragonimiasis in two villages near Chet Khot Waterfall, Kaeng Khoi District, investigated in 1984-1985 and 2005. The results from the 1980s showed 6.3% and 1% of villagers were positive for Paragonimus eggs in sputum and stool, respectively. In 2005, Paragonimus eggs were not found in feces or sputum. An IgG-ELISA for paragonimiasis was conducted on 33 serum samples collected in the 1980s, 23 collected in 2005 and 25 diagnosed with other parasitic infections. Ninety percent of the samples from the eighties were positive for paragoimiasis, and 43% from 2005 were positive, equivalent to 10.9% and 4.9% of the total population examined in the 1980s and 2005, respectively. Serodiagnosis is currently the best method for detecting paragonimiasis. The positive cases in the 1980s were age 10-60 years and in 2005 were age 34- 67-years-old. The prevalence and intensity of Paragonimus metacercariae in fresh Waterfall crabs collected from Chet Khot Waterfall were significantly lower in the 1980s than in 2005. The prevalence of paragonimiasis in this endemic area has decreased to the level that no egg-producing cases were detected. No infections were found in villagers age < 30 years, despite the high density of metacercariae in the crabs, indicating a change in the habit of eating raw food among the younger people.

Parasitological monitoring of helminth control program in Northern Thailand.

Nan Province, located in northern Thailand, is hyperendemic for parasite infections; the helminthic infection rate in 1,010 schoolchildren was 60.0% in 2001. Mass anthelmintic chemotherapy has been conducted with schoolchildren, and selective treatment has been given to people in the community, from 2002. The modified cellophane thick smear method was used to examine the prevalence and intensity of helminth infections in schoolchildren and community people once a year during the period 2002-2004. The prevalence of helminth infections decreased slowly from 60.0 to 40.3% in schoolchildren and from 70.8 to 60.0% in the older age population. Three parasite species were common: hookworm, Ascaris and Haplorchis, an intestinal trematode. Hookworm presented throughout the whole district. Ascaris infection occurred at high rates in some villages, while in some villages none was found. The villages where Ascaris infection was nil had high rates of Haplorchis infection, and vice versa. Most hookworm and Trichuris infections were of light intensity. Heavy intensity infection was found in 12.8-18.1% of Ascaris cases examined. Parasite infection rates in Chaloem Phra Kiat District can be classified as low prevalence.

Antibody isotype responses to paramyosin, a vaccine candidate for schistosomiasis, and their correlations with resistance and fibrosis in patients infected with Schistosoma japonicum in Leyte, The Philippines.

We examined whether antibody isotype responses to paramyosin (PM), a vaccine candidate for schistosomiasis, are associated with age-dependent resistance and pathology in liver fibrosis using human sera collected from 139 individuals infected with Schistosoma japonicum in Leyte, The Philippines. We report that IgA and IgG3 responses to PM showed a positive correlation with age and that the epitopes responsible were localized predominantly within the N-terminal half of PM. In addition, the IgG3 response to PM was associated with serum level of procollagen-III-peptide (P-III-P), an indicator of progression of liver fibrosis. These results imply that IgG3 against PM may not only provoke age-dependent resistance to S. japonicum infection but also enhance liver fibrosis. In contrast, levels of IgE to PM and to multiple PM fragments showed a negative correlation with P-III-P level. Thus, in contrast to IgG3, increases in PM-specific IgE may contribute to suppression of liver pathogenesis in schistosomiasis.

School-health-based parasite control initiatives: extending successful Japanese policies to Asia and Africa.

Japan controlled its major parasitic diseases by the 1970s. Based on this experience, the Government of Japan proposed the Global Parasite Control Initiative in 1998 and established three research and training centres around the world. The Asian Centre of International Parasite Control (ACIPAC) is the first such centre, and completed five years of activities focused on school-health-based parasite control in the Greater Mekong Subregion in 2005. The lessons learned and experiences gained by ACIPAC should be applied to all health promotion programmes worldwide.

Keys to success for a school-based malaria control program in primary schools in Thailand.

School-based malaria control has been recognized as a new approach for the control of this disease in the Greater Mekong Subregion since 2000. We evaluated a school-based malaria control program near the western border of Thailand using a before-after intervention study. The major intervention activities included teacher training with specialized malaria teaching materials and participatory learning methods. The target population was 17 school principals, 111 teachers and 852 schoolchildren of grade 3, 4, and 5 in 17 schools. After the intervention, the teachers taught about malaria more actively than before. The teachers who could design a lesson plan on malaria increased from 30.7% to 47.7% (p=0.015) and the teachers who had taught about malaria increased from 71.9% to 84.3% (p=0.035). As a result of the program, the schoolchildren changed their behavior positively towards malaria prevention with significant difference in 6 of 7 questions. For example, the schoolchildren 'who always took care of mosquito bites' increased from 42.7% to 62.1% (p<0.001) and the schoolchildren 'who always reported their parents or teachers when they had fever' increased from 36.0% to 56.0% (p<0.001). In conclusion, the keys to a successful intervention lie in good teaching materials and a participatory approach utilizing the well-established Thailand's school health system. Beyond Thailand, school-based malaria control could be applied to other Greater Mekong Subregion countries with careful analysis of school health context in each country.

Global parasite control initiative of Japan (Hashimoto Initiative).

The Asian Centre of International Parasite Control (ACIPAC) was established in Bangkok in March 2000 as a JICA technical cooperation project in collaboration with the Mahidol University and the Ministry of Public Health, Thailand. Since then, ACIPAC carried out its activities with emphasis on the establishment of the concept of school health-based parasite control in the Great Mekong sub-region countries. In addition to contributing human resource development through its training courses on school-based malaria and STH control for programme managers and also through small-scale pilot projects implemented in partner countries, ACIPAC proposed that schoolchildren should be considered as health partners rather than simple recipients of health services including deworming programmes.

The current situation regarding the establishment of national ethical guidelines for biomedical research in Thailand and its neighboring countries.

This study discusses the establishment of ethical guidelines for ethical review for biomedical research performed in Thailand, and to some extent, in neighboring countries. There are differences, from country to country, at national and institutional levels regarding guidelines for ethical review committees. Only a handbook issued by Mahidol University describes guidelines for human genetic research and on research dealing with reproductive technology. Both these areas require special consideration to avoid violating human dignity, rights, and confidentiality. This indicates that further efforts should be made to establish research guidelines and/or principles dealing with the human genome.

The Asian center of international parasite control (ACIPAC): five years of achievement. I. Introduction.

ACIPAC has made an effort to promote the concept of the school-based approach to malaria and STH control, mainly through human resource development, which could be eventually extended to any other health promotion program. Implementation of SSPP resulted in the establishment of national policies on parasite control and/or school health in some partner countries. It also provides a good opportunity for the formulation of partnerships among health and education sectors and international partners, although it did cause some problems concerning the enrollment of persons of authority from partner countries, and the staff of JICA resident offices as well. As described in the Joint Evaluation Report, ACIPAC is expected to further contribute to human resource development and to strengthening human resource and information networking at regional and global levels.

In vitro susceptibility and genetic variations for chloroquine and mefloquine in Plasmodium falciparum isolates from Thai-Myanmar border.

In vitro drug susceptibility to chloroquine (CQ) and mefloquine (MF) were assessed in 39 P. falciparum isolates from the Thai-Myanmar border area. To further characterize CQ- and MF-resistance profiles in this area, we also analyzed pfcrt K76T mutation that is critical for CQ resistance, and pfmdr1 polymorphism that has an association with MF resistance. Eighteen isolates were successfully examined by in vitro tests for CQ, and 17 of them had resistance to the drug. Geometric mean concentration of CQ that inhibited the growth of parasites at 50% (IC50) was 371 +/- 227 nM (105-971 nM). Sixteen isolates were successfully examined by in vitro tests for MF, and 8 of them were resistant to the drug. Geometric mean of IC50 for MF was 41 +/- 31 nM (4-125 nM). Genotypes of drug resistance, such as pfcrt and pfmdr1 mutations, were also analyzed. All the 39 isolates had the same haplotype (CVIET) for PfCRT at its 72-76th amino acids. A pfmdr1 Y86 mutation was found in 95% of isolates. A pfmdr1 D1042 mutation was also present in 7 isolates, while no pfmdr1 Y1246 mutation was observed. These results indicated a correlation between CQ resistance and the pfcrt T76 and pfmdr1 Y86 mutations.

Applicability of a monoclonal antibody-based dipstick in diagnosis of urinary schistosomiasis in the Central Region of Ghana.

Summary We tested a rapid visually read monoclonal antibody (MoAb) based dipstick assay for specific diagnosis of urinary schistosomiasis against microscopy and the use of haematuria and proteinuria in a schistosomiasis haematobia endemic area in the Central Region of Ghana. The study group consisted of 141 school children (83 males, 58 females) aged 8-19 years. A total of 129 of 141 (91.5%) submitted stool samples, and 7.8% had Schistosoma mansoni, 55% had hookworms and 6.2% had tapeworms. The presence of S. mansoni and intestinal parasites did not appear to influence the results of the MoAb-dipstick assay. The urinary schistosomiasis prevalence by MoAb-dipstick (78%) was higher (P < 0.05) than the estimate by microscopy (60.3%), microhaematuria (27%) and proteinuria (30.5%). The MoAb-dipstick correctly identified 98.8% of microscopically confirmed cases and missed one (1.3%). The dipstick was also positive for 26 of 56 (46.4%) egg-negative individuals, thereby giving a sensitivity of 98.8% and a specificity of 53.6%. On the other hand, microhaematuria and proteinuria were 38.8% and 30.6% sensitive, and 91.1% and 69.6% specific, respectively. Microhaematuria and proteinuria were less sensitive (P < 0.05) than both microscopy and MoAb-dipstick.

Overview: from the horse experimentation by Prof. Akira Fujinami to paramyosin.

Professor Akira Fujinami demonstrated for the first time in the world that acquired immunity might be induced against macroparasites such as schistosomes. Since then, vaccination models have been developed using various species of animals, among which the attenuated vaccine model in the mouse has been utilized mostly to clarify immune effector mechanisms and define candidate vaccine molecules. However, further studies are necessary on immune responses to defined parasite molecules in humans, because some discrepancies in immune responses still exist between animals and humans, and apparently genetic influence should be taken into consideration in such studies on defined molecules. Despite of some limitations, vaccine trials in livestock against Schistosoma japonicum may provide useful information for development of vaccines against the other human infections caused by S. mansoni or S. haematobium. In this overview, studies carried out mainly by Japanese investigators towards vaccine development will be described.

A potential role of interleukin 18 in severe falciparum malaria.

Interleukin-18 (IL-18) is a potent proinflammatory cytokine that induces interferon-gamma (IFN-gamma) production from Th1 cells, NK cells and activated macrophages, particularly in the presence of IL-12. However, it is also shown that without help from IL-12, IL-18 is capable of inducing IL-4 and IL-13 production in T cells, NK cells, mast cells and basophils, and that administration of IL-18 in conjunction with an allergen increases serum IgE levels. In order to clarify the role of IL-18 in disease severity of falciparum malaria, we have examined serum levels of IL-18, IFN-gamma, and IgE for 96 patients with falciparum malaria [Trans. R. Soc. Trop. Med. Hyg. 97, 236-241]. Results suggested that IL-18 plays a key role in inducing severe malaria through a pathway of elevating IFN-gamma, rather than its IgE inducing activity. Based on these results, the role of IL-18 in severe falciparum malaria will be discussed in this review.

The use of flow cytometry as a diagnostic test for malaria parasites.

A total of 453 clinical blood samples were determined for malaria parasites by flow cytometric assay (FCM) and reagents from Sysmex Corporation, Japan. In this study, the FCM greatly simplified and accelerated parasite detection, with sensitivity of 91.26%, specificity 86.28% and accuracy 87.42%. Overall, the parasite counts by flow cytometric measurement correlated well with the parasitemia measured by microscopic assay (regression coefficient = 0.9409). The detection limit was 0.05-0.1% parasitemia. No evidence of malaria parasites in either blood donor volunteers or other disease patients groups was determined by FCM. However, 48 samples who had been treated with antimalarial drugs and whose parasite microscopic counts were negative, showed false-positive results. When the data of these 48 samples were analyzed, they were found to have high levels of reticulocytes, ranging from 2.0-18.9%. This finding suggested that a high reticulocyte concentration in the blood may interfere with the performance of the FCM. Further improvement, by eliminating this interference, will make the FCM one of the most promising tests for malaria diagnosis.

Involvement of interleukin-18 in severe Plasmodium falciparum malaria.

Serum levels of interleukin-18 (IL-18), interferon-gamma (IFN-gamma), and immunoglobulin E (IgE) were determined for 96 patients with Plasmodium falciparum malaria admitted to hospital, Bangkok, Thailand in the period 1998-2000. The patients were divided into 3 groups, i.e. uncomplicated, severe and cerebral malaria according to WHO criteria (2000). Elevation of IL-18 levels was observed in all 3 groups, with a tendency for higher levels in cases with severe malaria throughout the course of the disease. Moreover, there was a significant correlation between IL-18 levels and the extent of parasitaemia among patients with severe malaria. However, IL-18 levels decreased more significantly in patients with cerebral malaria compared with the other groups in the late stage of the disease. Elevated levels of IFN-gamma were also observed in all groups of patients, especially in those with severe or cerebral malaria, and the levels in patients with cerebral malaria remained significantly higher than in those with uncomplicated malaria during days 4-7 post-treatment, suggesting the involvement of IFN-gamma in disease severity. Meanwhile, no significant difference was observed in IgE levels between the severe and uncomplicated groups of patients with helminth infection, although IgE levels were significantly higher in helminth-infected patients than uninfected patients. These results suggest that IL-18 plays a key role in inducing severe malaria through another pathway, such as elevation of IFN-gamma, rather than its IgE inducing activity.

Risk factors of helminthiases among schoolchildren in southern Thailand.

School-age children are particularly at risk of soil-transmitted helminthiasis (STH), which affects their growth and development. Hence, school-based helminthiasis control has been discussed and conducted as one of cost-effective ways in developing countries. A parasite control program is to be planned and conducted in an evidence based way as one of practical medical fields. However, a prevalence is likely to be influenced by various factors such as local environment and residents' behavior and so on. As few reports mentioning the relation of the prevalence and children's behavior and practice have been published, we conducted a survey to investigate such relation by asking children directly. Two hundred and eighty pupils in grade 3 to grade 5 were enrolled, who were in the two schools in Nakhon Si Thammarat Province, southern Thailand. A cross-sectional study was conducted in February and in November 2001, on the relationship between helminthiasis and children's knowledge and practice by using Kato-Katz method and a questionnaire, respectively. Hookworm (Hw) was the most predominant helminth followed by Trichuris. Boys had more intensive Hw infection than girls (p = 0.022), and wore shoes less frequently than girls (p < 0.001). The pupils who nearly acquired Hw infection after the first stool examination had lower levels of the knowledge of STH comparing to those who did not (p = 0.011). This study suggests that a prior survey can identify unique local factors as a part of diagnostic process, the results of which are useful for teachers to understand some points of health education at schools and can be applied as indicators for monitoring and evaluation.