Plerocercoids of Spirometra mansoni were collected from muscles of the frogs. Specimens were treated following the routine procedure, embedded， sliced and stained. The ultrastructure of plerocercoid was observed with transmission electron microscopy. It was found that the wall of plerocercoid consisted of tegument and parenchyma. Thornshape microtriches distributed over the outer surface of the tegument. Matrix zone had a lot of granular discoidal bodies， vesicles， mitochondria and endoplasmic reticulum. Most of the mitochondria were near the basal membrane. Parenchyma zone consisted of muscular layer， tegument cells， parenchymal cells， excretory system, and so on. Many cytoplasmic pathways of tegumentary cells strech into muscular layer, suggesting that the tegument may be the absorptive site of nutrients.

It has been 70 years to implement schistosomiasis control in China, which can be divided into five stages including the initiating preparedness, mass-based campaign, achievement consolidation, mass drug administration, control of infection source. A striking success in schistosomiasis control was achieved in China in the past decades with infected people declined from 9.49 million in 1957 to 30 000 in 2018. The great achievement is attributed to the central role of the Communist Party and the Government, integrated control, scientific strategies, and professional staff. The reduction and control of schistosomiasis could not come to truth without the leadership of endeavor of Communist Party and Government. In the march toward elimination the following measures are recommended, 1) improving the mechanism of schistosomiasis control and strengthening the leadership of governmental, 2) abiding by the law of disease control and making appropriate planning, 3) establishing the sensitive and effective surveillance system and focusing on the prevention, 4) promoting scientific management and implementing precision control.

Purified astrocytes were cultured in plates. When astrocytes grew over 80% of the plate, tachyzoites of Toxoplasma gondii RH strain were added for co-culture. In the period of 0-72 h, change of the astrocytes and tachyzoites was observed after Giemsa staining. In 0-48 h, monodansylcadaverine （MDC） was used to study the action of autophagy in the process of tachyzoites invading astrocytes. At 1 h co-culture, tachyzoites had entered in astrocytes and the autophagosomes appeared. At 4 h, the autophagosomes increased pronouncedly. However, after 12 h, number of autophagosomes considerably decreased and damage of the cells occurred. 48 h later, autophagosomes disappeared and more astrocytes were destroyed. At 72 h most cells destroyed and tachyzoites were released. The result showed that autophagy is inhibited when the astrocytes were in vitro infected by tachyzoites.

Objective To construct and express the recombinant plasmid pET32a-SjPGAM-SjEnol and evaluate its immuno-protective efficacy against the infection of Schistosoma japonicum in mice. Methods The peptides of SjPGAM and SjEnol containing the multivalent epitopes with higher binding capacity of human MHCⅡand mouse H2-dⅡ but low homology with the host were analyzed and screened through bioinfomatics. The corresponding nucleotide sequence of selected epitopes was spliced and the recombinant plasmid pET32a-SjPGAM-SjEnol was constructed and expressed in Escherichia coli BL21 cells. The antigenicity of the recombinant protein was detected by Western blotting and the protective effect induced with the recombinant was evaluated in mice. 55 BALB/c mice were randomly divided into 5 groups each with 11. Mice from groups A, B and C were injected with a mixture of recombinant protein （27 μg） pET32a-SjPGAM-SjEnol （A）, pET28a-SjPGAM （B） and pET28a-SjEnol （C） respectively together with 206 adjuvant, mice from groups D and E received adjuvant or PBS only, all injected for three times at two-week intervals. Mice were then challenged with 40±2 cercariae of S. japonicum at two weeks after the last vaccination, and sacrificed for perfusion by 6 weeks post infection. Adult worms were collected, the number of eggs in a gram of liver tissue was counted, and the rates of worm reduction and egg reduction were calculated. Serum samples were collected before vaccination, every one week after each inoculation and before sacrifice, and specific IgG was detected by ELISA. Results The sequences encoding the 96-147 aa of SjPGAM and 233-312 aa of SjEonl were chosen for constructing the recombinant plasmid, a cDNA fragment with the length of 447 bp was amplified by PCR. The recombinant plasmid was expressed in E. coli with a molecular weight of M_r 33 000. Western blotting revealed that the fusion protein was recognized by the rabbit serum specific to SjSWAP, and showed an adequate antigenicity. Vaccination experiment showed that when compared with those of the blank control, the worm reduction rate in group A was 39.7%, significantly higher than that of groups B （18.5%） and C （14.7%） （P<0.05）. The liver egg reduction rate in group A was 64.9%, also higher than that of groups B （47.5%, P<0.05） and C （30.5%, P<0.01）. ELISA showed that the serum specific IgG in group A （2.372±0.268） was much higher than that of groups D （0.490±0.138） （P<0.01） and E （0.220±0.088） （P<0.01）. Conclusion The recombinant plasmid pET32a-SjPGAM-SjEnol has been constructed, and recombinant protein pET32a-SjPGAM-SjEnol induces higher immuno-protection against S. japonicum than that of SjPGAM and SjEonl.

Objective To acquire the full coding sequence of Schistosoma japonicum aldehyde dehydrogenase, and fill the gaps of the partial aldehyde dehydrogenase sequences. Method Putative sequence fragments of the S. japonicum aldehyde dehydrogenase were extracted from the transcriptome database by use of bioinformatics tools, through the multiple sequences alignment with homologous sequences of other species. Primers were designed according to the EST sequences matching the N terminal and C terminal respectively, and the gap sequence fragment was amplified by RT-PCR and sequenced. The full gene sequence was obtained finally by combining the old 2 EST sequences with the amplified sequence. The physico-chemical parameters of the new sequence were analyzed by using bioinformatics software. Result Eight EST sequences of S.japonicum were predicted as partial sequences of aldehyde dehydrogenase. Two of which (AAW27891, AAW27047) were predicted to represent the N terminal and C terminal of one protein, respectively. The gap between them was deduced as about 80 amino acids according to the result of multiple sequences alignment. Primers located on the flanking of the gap were designed according to the known EST sequences of AAW27891 and AAW27047. The gap between the AAW27891 and AAW27047 were obtained by RT-PCR and then sequenced, as well as confirmed by bioinformatics software. The full sequence of aldehyde dehydrogenase was reassembled by filling of the gap sequence. The reassembled gene coding sequence was submitted to GenBank with an accession number of EF503564. The coding sequence contains an intact ORF of 1 596 bps with deduced 531 amino acids. Bioinformatic analysis of new amino acids sequence was performed as deduced molecular weight of 57 330.7 and PI value of 7.94. The aldehyde dehydragenase pattern of ［LIVMFGA］-E-［LIMSTAC］-［GS］-G-［KNLM］-［SADN］-［TAPFV］ was found located in the position 290-297 of the new sequence. Conclusion The gap between two partial nucleotide sequences is filled and the full coding sequence of aldehyde dehydrogenase gene has been obtained by the method combining bioinformatics tools and experiments together.

On the 70th anniversary of the People’s Republic of China, the author looks back to the national programs for parasite control started in the early 1950s and summarizes their accomplishments. On the nationwide scale, the transmission of schistosomiasis has been controlled, no indigenous case of malaria reported in 2017, lymphatic filariasis eliminated since 2006, local prevalence or sporadic cases of visceral leishmaniasis reported only in the western region, and soil-transmitted nematode infections decreased to a fairly low level which poses no more threat in most previously endemic areas. Evidently, these achievements come from the socialistic system which endorses a firm government commitment, the dedicated technical teams, and the community involvement. Though an outstanding success among the developing countries, continued endeavors are needed to finally eliminate the above-mentioned parasites but also to control hydatidosis, clonorchiasis and other zoonotic parasitic infections.

One hundred and fifty-three fecal samples of pet hamsters（Mesocricetus auratus, Phodopus sungorus, P. campbelli and P. roborovskii） were collected from a pet-market in Zhengzhou, and examined by Sheather?蒺s sugar flotation, modified acid-fast staining and Lugol?蒺s iodine-solution staining. The prevalence of parasites was 70.7%（41/58）, 96.7%（59/61）, 83.9%（26/31）, and 100%（3/3）respectively, with an overall prevalence of 84.3%. Eggs, cysts or oocysts of Cryptosporidium sp.（15.0%）, Giardia sp.（22.2%）, coccidian（2.0%）, Hymenolepis nana（31.4%）, Hymenolepis diminuta（25.5%）, Syphacia spp.（41.8％）, Aspiculuris tetraptera（7.2%） and undetermined Trichurata nematode（18.3%） were found from the samples. The results suggest that pet hamsters may be infected and transmit several zoonotic parasites.

Toxoplasma gondii is a ubiquitous, obligate intracellular protozoan parasite in human and animals. Chronic infection with this parasite is likely one of the most common infection in human. Following invasion of host cells T. gondii resides within membrane-bound vacuoles known as parasitophorous vacuole （PV）, which can protect the parasite from the endosomal acidification and lysosomal fusion of host cells. It plays an essential role in the whole parasitic process of T. gondii. This review summarizes the mechanism of PV formation and its function in the host cells.

Objective To identify new microsatellite loci from genome sequence database for the study of polymorphicsm of Schistosoma japonicum. Methods Schistosoma japonicum isolates were obtained from seven endemic sites in China： Tongling and Guichi counties of Anhui Province， Duchang county of Jiangxi Province， Changde and Yueyang Cities of Hunan Province， Shashi City of Hubei Province， Xichang City of Sichuan Province. In order to study the genetic variance， genomic DNAs of 96 individual adult worms were screened against 17 new Schistosoma japonicum microsatellites and the raw data were analyzed by GenMapper 4.0. Furthermore, the varieties of alleles were inverstigated using GenAlEx 6 and genetic distances within a subpopulation (GenClone) and among populations(UPGMA, MEGA 3.1) were analyzed. Results High levels of polymorphism were found between and within population samples， and significant genetic diversity was observed among the seven subpopulations.Within Jiangxi population, most genetic distances (17 loci) among samples range from 25 to 32, indicating a significant genetic diversity. There are three clusters among the seven populations: Jiangxi, Tonglin, Shashi and Changde population, with the genetics distances ranging from 0.017 8 to 0.036 3; Guichi and Yueyang population belong to another cluster, with the genetic distance of 0.024 7; However, Xichang population is an unique group. Its genetic distances to other populations are notable with a range from 0.019 2 to 0.069 3. Conclusion The 17 new polymorphic microsatellites identified may be used as suitable markers for the study on population genetics of Schistosoma japonicum and the genetic variance of the worms seems to be complicated.

An immunovariant adhesion protein family in Plasmodium falciparum named erythrocyte membrane protein 1（PfEMP1）, encoded by var genes, is responsible for both antigenic variation and cytoadhesion of infected erythrocytes at microvasculature sites throughout the body. The article summarizes antigen variation and pathogenicity, variation molecules expressed on infected erythrocytes, structure of var gene family, PfEMP1 adhesion properites, and regulation of variation in Plasmodium falciparum var gene family.

Objective To study the therapeutic effect on murine allergic asthma with recombinant Bla g 2 （rBla g 2）allergen and its possible mechanism. Methods Eighteen BALB/C mice were randomly divided into three groups: normal control group（group A）, asthma model group（group B）, and recombinant protein rBla g 2 treatment group（group C）. Mice in groups B and C were subcutaneously immunized weekly with rBla g 2（50 mg）formulated in Al（OH）3 adjuvant for three weeks. Group A received only adjuvant emulsified with normal saline. Two weeks after the last inoculation, mice in group C were administered each with rBla g 2（100 mg）/dose, and groups A and B were given PBS. All the mice received eight doses at 2-day intervals. One week after the last immunotherapy, mice in groups B and C were intranasally challenged with 50 mg rBla g 2 daily for seven days, while mice in group A received PBS. Twenty-four hours after the challenge, the following items were examined: airway hyperresponsiveness of mice, total cellular score and cell classification in bronchoalveolar lavage fluid（BALF）, level of rBla g 2-specific IgE and IgG2a in serum, lung inflammation by HE stain, and Bcl-2 expression of eosinophils of lung by immunohistochemistry. Results Compared with group B, group C showed a decreased Penh value of airway hyperresponsiveness（P＜0.05）, reduced serum rBla g 2-specific IgE but increased IgG2a（P＜0.01）, and reduced Bcl-2 expression of eosinophils. Total cells［（24.60±15.08）×105/ml］and eosinophils［（22.20±3.76）×105/ml］ in BALF of group B significantly increased than those of group C［（14.30±4.95）×105/ml and（5.20±1.56）×105/ml，respectively］（P＜0.01）. The interstitial space surrounding the airway lumen was characterized by a denseｌｙ mixed cellular infiltrate, tissue edema and epithelium tissue damage in group B, while lung inflamma-tion of group C reduced considerably. Each test value of group C was substantially similar to that of group A. Conclu-sion The experiment shows proper immunotherapeutic efficacy of rBla g 2 in murine allergic asthma, which may possi-bly related to the apoptosis of eosinophils.

Human African trypanosomiasis is caused by the infection of Trypanosoma brucei gambiense or T.b. rhodesiense， while another morphologically identical subspecies， T.b.brucei， and other closely related species， T.equiperdum and T.evansi， are considered not infectious to human. This is highly related to the trypanosome lytic factor （TLF） found in normal human serum （NHS） and the serum resistance-associated （SRA） protein of trypanosomes infectious to human. We reviewed the research progress in TLF and its role in trypanosome lysis as well as the mechanism of SRA against the TLF.

Objective To develop a multiplex PCR protocol for amplification of five Plasmodium falciparum drug resistance related genes， thereby facilitate the rapid and high throughput analysis of the drug resistance molecular markers. Methods Five pairs of primers were designed according to the reference sequences by using Primer Premier 5.0 and Oligo 6.0 software. Drug resistance related genes， including P. falciparum chloroquine resistance transporter （Pfcrt）， multi-drug resistance 1 （Pfmdr1）， dihydropteroate synthetase （Pfdhps）， dihydrofolate reductase （Pfdhfr） and sarco/endo-plasmic reticulum Ca ²⁺-ATPase（PfATPase6）， were amplified by single-tube multiplex PCR using Hot Start Taq DNA Poly-merase among negative controls （P. vivax， P. berghei， P. cynomolgi， Leishmania donovani， Cryptosporidium andersoni），blank control （using H₂O as template）， as well as P. falciparum laboratory isolates （3D7， Dd2， HB3， FCC1/HN and CMH/YN） and field samples （collected from Yunnan， Hainan of China and Myanmar）. After amplification， the PCR products were analyzed by agarose gel electrophoresis. The sequencing results were aligned to the reference sequence using BLAST. Results Five expected bands at 315， 437， 514， 594 and 770 bp were obtained with no additional or nonspecific products in P. falciparum laboratory isolates and field samples. The sequencing results were identical with the reference sequence except the polymorphism sites， and exhibited more than 98.5% homology. The multiplex amplification was performed successfully starting from 0.1 ng of DNA template. No band was observed in negative controls and blank control. Conclusion The present study establishes a method to amplify five Plasmodium falciparum drug resistance related genes harboring 21 SNPs by one-tube reaction. The multiplex PCR protocol showing high specificity and sensitivity is more convenient and efficient in analyzing the P. falciparum drug resistance molecular markers as compared with traditional nested PCR.

To observe the morphological changes of Toxocara canis egg development, an automatic microscopic photographing system was setup to track and record the whole process of T. canis egg development during continuous 21-day egg culture in vitro in this study. The results demonstrated that the whole development of T. canis egg in vitro was divided into 12 developmental stages including one-cell, two-cell, three-cell, four-cell, early-morula, late-morula, blastula, gastrula, pre-larva, L1 (the first stage larva), pre-L2 and L2 stages. The cell started to divide to form two-cell egg in 24 hours culture, appeared as 3-4 cells egg, morula, blastula and gastrula stages in 3-6 days. Total 22.5% of eggs developed to embryonated L1 with phototactic movements in 7 days. Total 10.67% eggs developed to infective embryonated L2 in 8 days. At 17-day post culture, the infective larva have been hatched and the whole eggshell collapsed. These data provide more information for the developmental biology of T. canis egg in vitro.

Objective To understand and analyze the current status and endemic trends of important human parasitic diseases, and provide scientific basis for the formulation of control programs in China. Methods The survey was carried out in 31 provinces (autonomous regions/municipalities) (hereinafter referred to as "P/A/Ms", excluding Hong Kong, Macao and Taiwan regions) of China from 2014 to 2016, using stratified cluster random sampling method. In rural areas, survey sites were selected based on the strata of ecological function in the nationwide eco-mapping and farmer’s income level (high, moderate and low annual net income per capita) in the county, by sampling 4-36 counties per province and 2-4 natural villages each sampled county. Totally, 1 890 survey sites were sampled, from each of them 250 permanent residents were surveyed by fecal examination for helminthes infection using modified Kato-Katz thick smear method (one sample, two slide-readings), applying saline smear and iodine solution smear method for protozoa infection, and by anal transparent tape test to examine Enterobius vermicularis infection for the children aged 3-6 years. In urban areas, however, only human Clonorchis sinensis infection was surveyed by fecal examination. For this purpose, the country was categorized into five endemic regions (I-V) based on the C. sinensis infection prevalence by region. A total of 517 survey sites were sampled, by selecting 2-37 counties from each province of all endemic regions, and taking urban resident community as the survey site. From each site, 250 permanent residents were surveyed for C. sinensis infection. Results A total of 617 441 people were surveyed in 31 P/A/Ms, comprising 484 210 from rural areas and 133 231 from urban areas, among them, 20 351 were found infected with important parasites (detection rate, 3.30%). A total of 34 species of parasites were found, including 23 helminth species and 11 protozoan species. The weighted infection rate of important parasites was 5.96%, accordingly, having estimated 38.59 million infected people. More specifically, the weighted infection rate of helminths was 5.10%, and that of intestinal protozoa was 0.99%, estimating 6.42 million people being infected. The weighted infection rate of soil-transmitted helminthes (STHs) was 4.49%, estimating 29.12 million people infected. The infection rate of Enterobius vermicularis was 3.43% in children aged 3-6 years, estimating 1.55 million infected children. The weighted infection rate of Taenia spp. was 0.06%, estimating 0.37 million infected. The weighted infection rate of C. sinensis in the country was 0.47%, estimating 5.98 million infected people. The weighted infection rate of C. sinensis in rural areas and urban areas was 0.23% and 0.71%, respectively, estimating 1.52 million and 4.46 million people infected. The important parasite infection displays an obvious regional distribution. The highly endemic areas of STHs infection were mainly distributed in Sichuan, Hainan, Guizhou, Yunnan, Chongqing, Guangxi, Guangdong and Jiangxi; the endemic areas of C. sinensis were restrictedly distributed in Guangdong, Guangxi, Heilongjiang and Jilin; the Taenia infection was mainly distributed in Tibet; and the highly endemic areas of E. vermicularis infection in children aged 3-6 years were mainly located in Hainan, Jiangxi, Guangdong, Guangxi, Guizhou and Chongqing. Over 50% of intestinal protozoa-infected people were distributed concentratedly in west China including Tibet, Guizhou and Guangxi. Conclusion The infection rate of important parasites, especially STHs, has been reduced significantly in China, showing a low level of prevalence or sporadically distributed in most of areas, and the scope of endemic regions has been markedly reduced as well. However, severe infection still exists in some provinces or local areas. The important parasite infection displays evident regional distribution pattern. Medium- and high-prevalence areas of STHs are mainly distributed in two broad regions in south and southwest China. The endemic areas of C. sinensis infection are mainly distributed in another two broad regions in southern and northeastern part of China. Taenia infection remains distributed in Tibet. The highly endemic areas of E. vermicularis infection in children aged 3-6 years are concentrated located in the southern and southwestern China. The intestinal protozoa infection is characterized with higher infection occurred in some limited areas, mainly distributed in western provinces. The number of people infected with important parasites in rural areas remains high, thus, prevention and control in this regard is still an arduous task.

Malaria is one of the oldest and most severe infectious diseases in China. After over 70 years of comprehensive control and prevention measures, great achievements have been made in malaria control in China, with a remarkable decline in morbidity and mortality. The malaria epidemic has been controlled effectively, ensuring people’s health, reducing the poverty due to illness, and promoting social and economic development. The milestone achievements in elimination of indigenous malaria cases nationwide has been maintained for 4 consecutive years since 2017, and thereafter the World Health Organization certificated malaria elimination in China on June 30, 2021, which is a significant milestone in the public health in China and the global history of malaria elimination. This paper systematically reviews the great impacts, performance characteristic and experiences gained from malaria elimination program, and the challenges in post-elimination stage in China.

In order to increase the recognition of intestinal parasitic infections in AIDS，this article reviews the common intestinal parasites co-infected in HIV carriers and AIDS patients，namely，Cryptosporidium spp.，microsporidia，Giardia lamblia，and Strongyloides stercoralis，referring to aetiology，epidemiology，clinical features，diagnosis and prevention.