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Activation of RIG-I signaling in the early stage of Paragonimus proliferus infection causes lung injury via type I immune response in rat

Paragonimiasis is a common zoonotic parasitic disease. The retinoic acid-inducible gene I (RIG-I) signaling is very important for the host to recognize invading pathogens (especially viruses and bacteria). However, the role of RIG-I signaling in the early stages of P. proliferus infection remains unclear. Therefore, in this study, Sprague-Dawley (SD) rat models with lung damage caused by P. proliferus were established. Experimental methods including Enzyme-linked Immuno Sorbent Assay (ELISA), real-time fluorescent quantitative polymerase chain reaction (PCR), western blotting, and hematoxylin and eosin (HE) staining were used to explore the mechanisms of lung injury caused by P. proliferus. As a result, the expression of the mRNA and proteins of RIG-I signal-related key target molecules, including RIG-I, tumor necrosis factor (TNF) receptor associated factor 6 (TRAF6), interferon regulatory Factor 7 (IRF7), IPS-1, and downstream C-X-C chemokine ligand 10 (CXCL10), were significantly up-regulated immediately after infection, peaked at 3 or 7 days, and showed a downward trend on after 14 days. The levels of pro-inflammatory cytokines interleukin-1 (IL-1), interferon (IFN)-α, -β, and -γ, which represent type 1 immune response, gradually increased and reached a peak by 14 days, which was consistent with the changes in the degree of inflammatory damage observed under HE staining of lung tissues. In conclusion, RIG-I signaling is activated in the early stage (before 14 days) of P. proliferus infection, it is inferred that the lung injury of the host may be related to the activation of RIG-I like signaling to induce type I immune response.

[Sequence analysis of Paragonimus internal transcribed spacer 2 and cyclooxygenase 1 genes in freshwater crabs in Henan Province]

OBJECTIVE

To investigate the sequences of internal transcribed spacer 2 (ITS2) and cyclooxygenase 1 (COX1) genes of Paragonimus metacercariae in freshwater crabs in Henan Province, identify the species of Paragonimus and evaluate its genetic relationships with Paragonimus isolates from other provinces in China.

METHODS

Freshwater crabs were collected from 8 survey sites in Zhengzhou, Luoyang, Pingdingshan, Nanyang and Jiyuan cities of Henan Province from 2016 to 2021, and Paragonimus metacercariae were detected in freshwater crabs. Genomic DNA was extracted from Paragonimus metacercariae, and the ITS2 and COX1 genes were amplified using PCR assay, followed by sequencing of PCR amplification products. The gene sequences were spliced and aligned using the software DNASTAR, and aligned with the sequences of Paragonimus genes in the GenBank. Phylogenetic trees were created using the MEGA6 software with the Neighbor-Joining method based on ITS2 and COX1 gene sequences, with Fasciola hepatica as the outgroup.

RESULTS

The detection rates of Paragonimus metacercariae were 6.83% (11/161), 50.82% (31/61), 18.52% (5/26), 8.76% (12/137), 14.29% (9/63), 17.76% (19/105), 18.50% (32/173) and 42.71% (41/96) in freshwater crabs from 8 survey sites in Zhengzhou, Luoyang, Pingdingshan, Nanyang and Jiyuan cities of Henan Province, with a mean detection rate of 19.46% (160/822), and a mean infection intensity of 0.57 metacercariae/g. The amplified ITS2 and COX1 gene fragments of Paragonimus were approximately 500 bp and 450 bp in lengths, respectively. The ITS2 gene sequences of Paragonimus metacercariae from 8 survey sites of Henan Province showed the highest homology (99.8% to 100.0%) with the gene sequence of P. skrjabini (GenBank accession number: MW960209.1), and phylogenetic analysis showed that the Paragonimus in this study was clustered into the same clade with P. skrjabini from Sichuan Province (GenBank accession number: AY618747.1), Guangxi Zhuang Autonomous Region (GenBank accession number: AY618729.1) and Hubei Province (GenBank accession number: AY618751.1), and P. miyazaki from Fujian Province (GenBank accession number: AY618741.1) and Japan (GenBank accession number: AB713405.1). The COX1 gene sequences of Paragonimus metacercariae from 8 survey sites of Henan Province showed the highest homology (90.0% to 100.0%) with the gene sequence of P. skrjabini (GenBank accession number: AY618798.1), and phylogenetic analysis showed that the Paragonimus in this study was clustered into the same clade with all P. skrjabini and clustered into the same sub-clade with P. skrjabini from Hubei Province (GenBank accession numbers: AY618782.1 and AY618764.1).

CONCLUSIONS

Paragonimus species from freshwater crabs in Henan Province were all characterized as P. skrjabini, and the ITS2 and COX1 gene sequences had the highest homology to those of P. skrjabini from Hubei Province. The results provide insights into study of Paragonimus in Henan Province and China.

Global prevalence of 4 neglected foodborne trematodes targeted for control by WHO: A scoping review to highlight the gaps

BACKGROUND

Foodborne trematodiases (FBTs) are a group of trematodes targeted for control as part of the World Health Organization (WHO) road map for neglected tropical diseases from 2021 to 2030. Disease mapping; surveillance; and capacity, awareness, and advocacy building are critical to reach the 2030 targets. This review aims to synthesise available data on FBT prevalence, risk factors, prevention, testing, and treatment.

METHODS

We searched the scientific literature and extracted prevalence data as well as qualitative data on the geographical and sociocultural risk factors associated with infection, preventive/protective factors, and methods and challenges of diagnostics and treatment. We also extracted WHO Global Health Observatory data representing the countries that reported FBTs during 2010 to 2019.

RESULTS

One hundred and fifteen studies reporting data on any of the 4 FBTs of focus (Fasciola spp., Paragonimus spp., Clonorchis sp., and Opisthorchis spp.) were included in the final selection. Opisthorchiasis was the most commonly reported and researched FBT, with recorded study prevalence ranging from 0.66% to 88.7% in Asia, and this was the highest FBT prevalence overall. The highest recorded study prevalence for clonorchiasis was 59.6%, reported in Asia. Fascioliasis was reported in all regions, with the highest prevalence of 24.77% reported in the Americas. The least data was available on paragonimiasis, with the highest reported study prevalence of 14.9% in Africa. WHO Global Health Observatory data indicated 93/224 (42%) countries reported at least 1 FBT and 26 countries are likely co-endemic to 2 or more FBTs. However, only 3 countries had conducted prevalence estimates for multiple FBTs in the published literature between 2010 to 2020. Despite differing epidemiology, there were overlapping risk factors for all FBTs in all geographical areas, including proximity to rural and agricultural environments; consumption of raw contaminated food; and limited water, hygiene, and sanitation. Mass drug administration and increased awareness and health education were commonly reported preventive factors for all FBTs. FBTs were primarily diagnosed using faecal parasitological testing. Triclabendazole was the most reported treatment for fascioliasis, while praziquantel was the primary treatment for paragonimiasis, clonorchiasis, and opisthorchiasis. Low sensitivity of diagnostic tests as well as reinfection due to continued high-risk food consumption habits were common factors.

CONCLUSION

This review presents an up-to-date synthesis on the quantitative and qualitative evidence available for the 4 FBTs. The data show a large gap between what is being estimated and what is being reported. Although progress has been made with control programmes in several endemic areas, sustained effort is needed to improve surveillance data on FBTs and identify endemic and high-risk areas for environmental exposures, through a One Health approach, to achieve the 2030 goals of FBT prevention.

Comparative proteomics of adult Paragonimus kellicotti excretion/secretion products released in vitro or present in the lung cyst nodule

Paragonimus kellicotti is a zoonotic lung fluke infection, the agent of North American paragonimiasis, and an excellent model for other Paragonimus infections. The excretory/secretory proteins (ESP) released by parasites and presented at the parasite-host interface are frequently proposed to be useful targets for drugs and/or vaccines In vitro culture conditions may alter ESP compared to those produced in vivo. In order to investigate ESPs produced in vivo we took advantage of the fact that adult P. kellicotti reproduce in the lungs of experimentally infected gerbils in tissue cysts. We performed a mass-spectrometric analysis of adult P. kellicotti soluble somatic protein (SSPs) extracts, excreted/secreted proteins (ESPs) produced by adult worms during in vitro culture, and lung cyst fluid proteins (CFPs) from experimentally infected gerbils. We identified 2,137 P. kellicotti proteins that were present in at least two of three biological replicates and supported by at least two peptides. Among those were 1,914 proteins found in SSP, 947 in ESP and 37 in CFP. In silico analysis predicted that only 141 of the total 2,137 proteins were secreted via classical or non-classical pathways. The most abundant functional categories in SSP were storage and oxidative metabolism. The most abundant categories in ESP were proteins related to metabolism and signal transduction. The 37 parasite-related proteins in CFP belonged to 11 functional categories. The largest groups were proteins with unknown function, cytoskeletal proteins and proteasome machinery. 29 of these 37 proteins were shared among all three sample types. To our knowledge, this is the first study that compares in vitro and in vivo ESP for any Paragonimus species. This study has provided new insights into ESPs of food-borne trematodes that are produced and released in vivo. Proteins released at the host-parasite interface may help the parasite evade host immunity and may represent new targets for novel treatments or diagnostic tests for paragonimiasis.

Parasitic Infection Misdiagnosed As Bacterial Pneumonia: A Case Report

Bacterial pneumonia is a common lung disorder, and the pathogenesis remain elusive. Parasitic infections of the lung are able to affect the respiratory system, and the clinical features could mimic tuberculosis and malignancy. Therefore, it is essential to identify parasitic pneumonia at early stage, and most cases are curable with medical intervention. In this study, one case of parasitic pneumonia was misdiagnosed as bacterial infection, revealing the importance of pathological biopsy and MDT, especially when clinical features are not typical and routine tests are not specific. Therefore, more paragonimiasis cases can be diagnosed more effectively by the clinicians and misdiagnose should be avoided in future clinical practice.

[Proteomics analysis of Paragonimus skrjabini]

OBJECTIVE

To perform a proteomics analysis for metacercariae, juvenile and adult worms of Paragonimus skrjabini.

METHODS

Crabs were collected in P. skrjabini endemic areas of Kaiyang and Bijie in Guizhou Province. Metacercariae were isolated, placed in PBS, and were used to infect three SD rats(10 metacercariae/rat) by intragastric administration and infect three male dogs(20 metacercariae/dog) through feeding. The rats were sacrificed at 1 month after infection to obtain juvenile worms. The dogs were sacrificed at 3 months after infection to obtain adult worms. The metacercariae, juvenile and adult worms were lysed, and total protein was extracted by ultrasonication. The total protein content was determined by Bradford method and separated by SDS-PAGE and two dimensional gel electrophoresis. Images of two dimensional gel electrophoresis were analyzed using the PDquest 8.0 software. The dots with difference were digested and analyzed with mass spectrometry. Finally, online searches in NCBI and local databases were performed.

RESULTS

Results of SDS-PAGE showed that the total protein of metacercariae, juvenile and adult worms was concentrated within Mr of 25 000-116 000. Fifty-one protein dots with difference were found by two dimensional gel electrophoresis, comprising of 20 dots for metacercariae, 25 for juvenile worms and 6 for adult worms. Thirty-six peptide sequences of metacercariae and juvenile worms were analyzed. They were basically determined to be Achrornobacter lyticus protease Ⅰ(a lysine-specific serine protease), ascorbate reductase protein, glutathione s-transferase DHAR2 analogue, heat shock proteins Hsp82 and Hsp96-β, actin, cystatin, etc., by online searches, and cysteine, actin and heat shock protein by local searches in the diginea database(downloaded to a local computer from NCBI). Mass spectrometry was not performed for adult worms, as the variation of grayscale value between their spots was far less than those for metacercariae and juvenile worms.

CONCLUSION

One difference is that the metacercariae of P. skrjabini have actin, while the juvenile worms have detoxification proteins and stress proteins. But they both have hydrolases and cysteine enzymes.

[An Investigation on a Case of Family-clustered Paragonimiasis in Wenzhou City]

Paragonimus infection was reported in a family of 8 members after consuming wine-preserved raw crabs. Seven members developed symptoms of fever, cough, sputum, fatigueness, chest pain, and abdominal pain during 2-3 months after crab feeding, while one member was normal. Serum samples were collected from the 7 members for anti-paragonimus antibody test, with 5 members showing positive, 1 weakly positive and 1 negative. In view of the epidemiological history, clinical symptoms, imaging and laboratory test results, this case was diagnosed to be a family-clustered paragonimus infection.

[Establishment of Magnetic Affinity Enzyme Linked Immunoassay Based on Schistosoma japonicum Recombinant Antigen Sj26 and Its Application in Detection of Serum Antibody with Low Intensity of Infection]

OBJECTIVE

To develop the magnetic affinity enzyme-linked immunoassay (MEIA) using recombinant glutathione-S-transferase of Schistosoma japonicum with a relative molecular weight of 26 000（rSj26-MEIA） for antibody detection under low intensity infection.

METHODS

The recombinant plasmid pET28a-Sj26 was transformed into Escherichia coli strain BL21, and 0.6 mmol/L isopropyl β-D-1-thiogalactopyranoside （IPTG） was used to induce its expression. The expression products were purified by Ni2+ （nickel sulfate） affinity chromatography, SDS-PAGE and Western blotting were performed to examine the expression of rSj26. The purified rSj26 was coupled to magnetic beads as capture antigen and the reaction conditions were optimized to establish the rSj26-MEIA method. The method was then used to analyze 58 serum samples from patients with low-intensity S. japonicum infection, 30 serum samples from non-endemic areas as a negative control, and 6 serum samples from patients with paragonimus infection. Results were compared with those obtained with ELISA.

RESULTS

The concentration of purified rSj26 was 2.5 mg/ml. The rSj26 had a relative molecular weight of 27 000 and was expressed mainly in the soluble form as revealed by SDS-PAGE. It could be recognized by rabbit and murine sera infected with S. japonicum as shown by Western blotting. Optimization of rSj26-MEIA revealed that use of 0.2 mg magnetic beads loaded with 10 μg rSj26 and serum sample dilution at 1 ∶ 100 yielded the highest ratio of the mean A550 of positive serum to the mean A550 of negative sample (P/N)（3.97）. For serum samples from patients with low-intensity S. japonicum infection, rSj26-MEIA and rSj26-ELISA both resulted in a positive detection rate of 24.14%（14/58）, and P/N values of 3.61 and 2.56. In addition, Pearson′s correlation analysis revealed positive correlation between A550 values detected by rSj26-MEIA and by rSj26-ELISA（r=0.658, P<0.01）. Further, no positive reaction was found in the 6 serum samples from patients with paragonimus infection and in the 30 serum samples from non-endemic areas, either by rSj26-MEIA or by rSj26-ELISA.

CONCLUSION

rSj26-MEIA may be used as a new technique for detection of serum antibody against S. japonicum infection with low intensity.

[A Retrospective Analysis on 47 Children with Paragonimiasis in Ningbo City]

A retrospective analysis was performed on 47 children diagnosed with paragonimiasis in Ningbo Women and Children’s Hospital from January 2004 to December 2014. The 47 children comprised 32 boys （68.1%） and 15 girls （48.9%）, and 24 cases（51.1%） in urban areas and 23 （48.9%） in rural areas （P>0.05）. There was a trend of increase in paragonimiasis occurrence in preschoolers since 2010. Forty-three cases had a history of eating raw or wine-preserved crabs and 4 cases had a history of drinking raw stream water． There were 2 cases of paragonimus encephalopathy and one case accompanied by subcutaneous nodules. Thirty-nine cases showed increases in eosinophil number and proportion in peripheral blood, and 29 cases showed increased serum IgE level. Forty-seven cases had negative results for detection of paragonimus eggs in sputum and stool. The dot immuno-gold filtration-assay and ELISA showed a 100% positive rate for paragonimus serum antibody. All the 47 cases were administered with praziquantel after diagnosis, and no adverse effect was reported during the treatment.

[Retrospective analysis of 39 child cases of paragonimiasis]

Clinical data of 39 children with paragonimiasis treated in Chongqing Three Gorges Central Hospital during 2008-2010 were retrospectively analyzed. The cases aged from 3 to 10 years old, with 25 cases of polyserositis (64.1%), 14 cases of cerebral paragonimiasis (35.9%). Among the cases of polyserositis, all showed dyspnea,tachypnea and diminished respiration (100%). Other symptoms or signs included purulent pleurisy, orthopnea, restricted activity, distant heart sounds, purulent pericarditis, abdominal distension, and hepatomegaly. In the 14 cases of cerebral paragonimiasis, 10 cases (71.4%) complained headache, 8 cases (57.1%) with vomiting, and other symptoms such as seizures, limb rigidity associated with conscious disturbance. Eight patients were treated with surgery and praziquantel, while others with praziquantel alone. After treatment 25 cases (64.1%) were cured, 13 cases (33.3%) improved, and 1 case (2.6%) showed no change.

Tropical pulmonary diseases

The term 'tropical' refers to the region of the Earth lying between the Tropic of Cancer and the Tropic of Capricorn. Located between these equatorial parallels demarcating the Torrid Zone are several underdeveloped and developing countries: Thailand, the Philippines, Malaysia, Singapore, Indonesia, southern India, Sri Lanka, Brazil, Cuba, Ethiopia, Sudan and Nigeria, to name but a few considered to be 'tropical'. The climate in most of these countries is characterized by high temperatures and high humidity. The tropical climate and general state of socio-economic underdevelopment in such countries provide an ideal environment for pathogenic organisms, their vectors and intermediate hosts to flourish. Furthermore, the cultural habits and educational background of the people living in such countries expose them to pathogens and, when these people become infected, they readily become reservoirs for, or carriers of, those organisms. Ultimately, the adverse socioeconomic conditions of underdeveloped countries impede attempts to eradicate or control tropical diseases.

[A case of pelvic paragonimiasis combined with myoma uteri and pelvic inflammatory disease]

Paragonimus westermani is a lung fluke of humans that is usually found in the lungs but may be found elsewhere in many unusual locations. A case of pelvic paragonimiasis was found incidentally by surgical intervention of inflammatory disease and myoma uteri. She was a 51-year-old Korean woman complaining of lower abdominal pain and intermittent vaginal spotting. Numerous Paragonimus ova were observed in the resected omentum in the pelvis after total abdominal hysterectomy. It is suggested that pelvic paragonimiasis may be one of causative agents of pelvic inflammatory disease.

Parasitic infections of the pleural space

Parasitic infections are a sufficiently common cause of pleural disease that parasitosis should be considered in any effusion of unclear cause. They can involve the pleura with or without involvement of the adjacent lung. Amebiasis affects the pleural by crossing the diaphragm from a liver abscess. This is particularly important to diagnose because of the ease of treatment and the severe course of the untreated disease; the gross appearance of the pus may be diagnostic. Cystic hydatid disease can be primarily pleural, but more often reaches the pleura by rupture of a cyst in the lung or liver. Rupture often calls for aggressive surgical treatment; it may be complicated immediately by anaphylaxis, earlier by empyema or lung abscess, and later by secondary disseminated hydatidosis. Pleural paragonimiasis is often mistaken for tuberculosis. Patients are not likely to have diagnostic eggs in the sputum or stool, but the pleural fluid is characteristic. Other parasitic infections that have rarely been associated with pleural disease include pneumocystosis, Loeffler's syndrome, tropical pulmonary eosinophilia, toxocariasis, anisakiasis, hypodermiasis, strongyloidiasis, and schistosomiasis. Some parasites, including pentastomids and Mansonella sp, can be found in the pleura incidentally by radiograph or autopsy, but seldom if ever cause pleural disease.

PULMONARY MANIFESTATIONS OF PARASITIC INFESTATIONS

Parasitic infestations in man may cause transient or permanent pulmonary lesions. The lesions occur during migration and evolution of the parasites, during parasitemia, or during the final habitat. These manifestations, though infrequent in Canadian medical practice, present difficulties in diagnosis. Life cycles, mode of entry, and migration of parasites in the human body are described and illustrative case histories presented. In this series, transient pulmonary changes were associated with Ascaris lumbricoides, Ankylostoma duodenale, filariasis, Giardia lamblia and Trichinella spiralis; permanent lesions were produced by Entameba histolytica and Tenia echinococcus. Other parasites which may produce pulmonary changes are Strongyloides stercoralis and several types of Filaria (transient); Schistosoma, Paragonimus westermani (permanent). A case of amebiasis is presented illustrating the latent stage of infestation which lasted several decades before the organism spread from bowel to para-aortic nodes, to the lumen of the inferior cava, thence to the radicles of the portal vein and lung.