Regulatory compliance and readability of informed consent forms in industry-sponsored drug development clinical trials

BACKGROUND/AIMS

An informed consent form is essential in drug development clinical trials. This study aimed to evaluate regulatory compliance and readability of informed consent forms currently being used in industry-sponsored drug development clinical trials.

METHODS

This descriptive, cross-sectional study evaluated the informed consent forms of industry-sponsored drug development clinical trials conducted at the Faculty of Medicine, Chiang Mai University, between 2019 and 2020. The informed consent form's compliance with the three major ethical guidelines and regulations (i.e. International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use E6(R2) Good Clinical Practice; Declaration of Helsinki; and the revised Common Rule) were analyzed. The document length and the readability scores (using Flesch Reading Ease and Flesch-Kincaid Reading Grade) were assessed.

RESULTS

Of 64 reviewed informed consent forms, the average page length was 22.0 ± 7.4 pages. More than half of their length was mainly devoted to three elements: trial procedures (22.9%), risks and discomforts (19.1%), and confidentiality and the limit of confidentiality (10.1%). Although most of the required elements of the informed consent form content were included in most informed consent forms, we identified four elements with often missing information in the form: aspects of research that are experimental (n = 43, 67.2%), involvement of whole-genome sequencing (n = 35, 54.7%), commercial profit sharing (n = 31, 48.4%), and posttrial provisions (n = 28, 43.8%).

CONCLUSION

The informed consent forms in industry-sponsored drug development clinical trials were long but incomplete. Our findings draw attention to ongoing challenges in industry-sponsored drug development clinical trials, where deficient informed consent form quality continues to exist.

What information and the extent of information to be provided in an informed assent/consent form of pediatric drug trials

Background

This study aimed to determine the elements and the extent of information that child participants and their parents would like to read in an informed assent form (IAF)/informed consent form (ICF) of a pediatric drug trial.

Methods

A descriptive survey was conducted to determine the perceived importance of each element of the ICF content from child participants and their parents who underwent informed assent/consent of a multi-center pediatric drug trial. The respondents were asked to indicate the level of importance of each item in a questionnaire, by giving a rating scale from 1 (not important) to 5 (very important).

Results

A total of 22 families, 17 child participants with the diagnosis of hematology or oncology diseases and 27 parents, were enrolled. Among 30 items, risk–benefit aspects (i.e., direct health benefit [mean: 4.71 for child respondents, 4.89 for parent respondents], indirect/societal benefit [mean: 4.65, 4.85], major foreseeable risk [mean: 4.47, 4.78], post-trial benefit/provision [mean: 4.59, 4.74], and all adverse effects of the drug including uncommon adverse effects [mean: 4.53, 4.74]) were perceived to be of most concerning items from both child participants’ and parents’ viewpoint. None of the items were considered ‘slightly important’ or lower by more than 20% of the respondents.

Conclusions

For pediatric drug trials, risk–benefit information (including direct health benefit, indirect/societal benefit, and post-trial benefit/provision, as well as major foreseeable risk and adverse effects of the drug) should be made a salient feature of an IAF/ICF. This empirical data could help related stakeholders arrange essential information in order of importance and tailor an IAF/ICF to better suit child participants’ and parents’ needs, particularly for pediatric drug trials involving children with the diagnosis of hematology or oncology diseases.

Ethical considerations and challenges in herbal drug trials with the focus on scientific validity and risk assessment

Scientific validity and risk assessment are two main ethical issues which raise specific challenges and are unique to clinical trials investigating crude extracts/fractions from herbal materials. There are considerable challenges for both clinical investigators and ethics committee members in dealing with such issues, many of them remain unresolved, resulting in a large variation in ethical requirements, justification, and decisions. Despite a remarkable surge in herbal medicine research globally, a number of clinical investigators or even ethics committee members have limited confidence in dealing with related ethical issues. In this article, we extensively review and discuss the two main ethical issues (i.e., scientific validity and risk assessment) and highlight key considerations that are important for ethical review and justification for the conduct of herbal drug trials.

Morphology of immature stages of flesh flies, Boettcherisca nathani and Lioproctia pattoni (Diptera: Sarcophagidae)

The flesh flies are medically-important because the larvae found in the human corpses can provide evidence in forensic investigations through larva identification and their developmental rate. Firstly, we thoroughly described the larval morphology of Boettcherisca nathani and Lioproctia pattoni, using scanning electron microscopy (SEM). The third instar of the two species differed markedly in two characters: (1) spines between the prothorax and mesothorax-B. nathani has more or less slender triangular spines, with those at the posterior region more slender than the anterior region; whereas L. pattoni has stout triangular spines with one or two tips anteriorly, with smaller and tapered triangular shape, grouped two to four laterally in the posterior end, and (2) morphology of the peristigmatic tufts at the posterior spiracle-B. nathani has extensively branched long, fine hairs, whereas tufts in L. pattoni have moderately branched long, fine hairs. The anterior spiracle displayed similarity; B. nathani has two irregular rows of 21-27 papillae, while L. pattoni has a single irregular row of 20-28 papillae. Secondly, we use light microscopy to compare morphology of the third instar of the two species and additional three species, i.e., Bercaea africa, Parasarcophaga dux and Liopygia ruficornis. Particular attention was paid to the features of anterior spiracle, spines between prothorax and mesothorax and posterior spiracle. These results are useful in species identification and estimation of age of larvae found associated with corpses.

Taeniasis among Refugees Living on Thailand-Myanmar Border, 2012

We tested refugee camp residents on the Thailand–Myanmar border for Taenia solium infection. Taeniasis prevalence was consistent with that for other disease-endemic regions, but seropositivity indicating T. solium taeniasis was rare. Seropositivity indicating cysticercosis was 5.5% in humans, and 3.2% in pigs. Corralling pigs and providing latrines may control transmission of these tapeworms within this camp.

Detection of Ehrlichia canis in canine blood samples by real-time fluorescence resonance energy transfer (FRET) PCR and melting curve analysis

Ehrlichia canis is a small pleomorphic gram-negative, coccoid, obligatory intracellular bacterium and the cause of canine monocytic ehrlichiosis. A real-time fluorescence resonance energy transfer polymerase chain reaction (real-time FRET PCR) coupled with melting curve analysis was established for detection of E. canis infection in canine blood samples. The VirB9 gene was amplified using one pair of primers and the melting curve analysis was generated by heating the hybridizing probes and amplified products. Eight E. canis-infected dog blood samples were initially identified using the Giemsa staining/microscopic method followed by conventional PCR (cPCR)/Sanger sequencing for confirmation. The sensitivity and specificity of the real-time FRET PCR detection were 87.5% and 100%, respectively and the limit of detection was 6.6 x 10(3) copies of positive E. canis control plasmids. The real-time FRET PCR with melting curve analysis reported here is better than microscopic visualization or cPCR because the method is not affected by the false bias inherent in the microscopic method. Furthermore, many samples can be processed rapidly at the same time. This convenient tool is beneficial as an alternative assay for the epidemiologic study of canine ehrlichiosis as well as for eradication of these organisms in prevention and control programs in endemic areas.

Morphology of puparia of flesh flies in Thailand

Puparia of five flesh fly species were investigated for forensic study. Boettcherisca nathani (Lopes, 1961), Boettcherisca peregrina (Robineau-Desvoidy, 1830), Lioproctia pattoni (Senior-White, 1924), Liopygia ruficornis (Fabricius, 1794) and Parasarcophaga (Liosarcophaga) dux (Thomson, 1869) were examined with a scanning electron microscopy (SEM). Differences between species were found in the number and arrangement of papillae in the anterior spiracle, the shape of intersegmental spines between the prothorax and mesothorax and the pattern of spiracular tufts at the posterior spiracle. The anterior spiracle of B. nathani had two rows, comprising 21-27 papillae; while those of B. peregrina and L. pattoni had one or two irregular rows with 24-26 and 20-28 papillae, respectively. Anterior spiracle of L. ruficornis and P. dux had one row of 10-15 papillae. Intersegmental spines between the prothorax and mesothorax and pattern of spiracular tufts at the posterior spiracle are morphologically different. L. ruficornis and P. dux puparia are similar, but the position of the interslit plate between the inner and middle spiracular slits was found to be an important attribute to separate both species. Morphometric analysis on the length and width of puparia of these species revealed statistically different among them. The key for identifying puparia of forensically important flesh flies has been provided.

Potentially pathogenic free-living amoebae in some flood-affected areas during 2011 Chiang Mai flood

SUMMARY

The survey was carried out to investigate the presence of potentially pathogenic free-living amoebae (FLA) during flood in Chiang Mai, Thailand in 2011. From different crisis flood areas, seven water samples were collected and tested for the presence of amoebae using culture and molecular methods. By monoxenic culture, FLA were detected from all samples at 37 °C incubation. The FLA growing at 37 °C were morphologically identified as Acanthamoeba spp., Naegleria spp. and some unidentified amoebae. Only three samples (42.8%), defined as thermotolerant FLA, continued to grow at 42 °C. By molecular methods, two non-thermotolerant FlA were shown to have 99% identity to Acanthamoeba sp. and 98% identity to Hartmannella vermiformis while the two thermotolerant FLA were identified as Echinamoeba exundans (100% identity) and Hartmannella sp. (99% identity). This first report of the occurrence of FLA in water during the flood disaster will provide information to the public to be aware of potentially pathogenic FLA.

Susceptibility of laboratory rodents to Trichinella papuae

Members of the genus Trichinella are small nematodes that can infect a wide range of animal hosts. However, their infectivity varies depending on the parasite and host species combination. In this study, we examined the susceptibility of 4 species of laboratory rodents, i.e., mice, rats, hamsters, and gerbils to Trichinella papuae, an emerging non-encapsulated Trichinella species. Trichinella spiralis and Trichinella pseudospiralis were also included in this study for comparison. Fifteen animals of each rodent species were infected orally with 100 muscle larvae of each Trichinella species. Intestinal worm burden was determined at day 6 and 10 post-inoculation (PI). The numbers of muscle larvae were examined at day 45 PI. The reproductive capacity index (RCI) of the 3 Trichinella species in different rodent hosts was determined. By day 6 PI, 33.2-69.6% of the inoculated larvae of the 3 Trichinella species became adult worms in the small intestines of the host animals. However, in rats, more than 96% of adult worms of all 3 Trichinella species were expelled from the gut by day 10 PI. In gerbils, only 4.8-18.1% of adult worms were expelled by day 10 PI. In accordance with the intestinal worm burden and the persistence of adults, the RCI was the highest in gerbils with values of 241.5±41.0 for T. papuae, 432.6±48 for T. pseudospiralis, and 528.6±20.6 for T. spiralis. Hamsters ranked second and mice ranked third in susceptibility in terms of the RCI, Rats yielded the lowest parasite RCI for all 3 Trichinella species. Gerbils may be an alternative laboratory animal for isolation and maintenance of Trichinella spp.

Evaluation of IgG4 subclass antibody detection by peptide-based ELISA for the diagnosis of human paragonimiasis heterotrema

A synthetic peptide was prepared based on the antigenic region of Paragonimus westermani pre-procathepsin L, and its applicability for immunodiagnosis for human paragonimiasis (due to Paragonimus heterotremus) was tested using an ELISA to detect IgG4 antibodies in the sera of patients. Sera from other helminthiases, tuberculosis, and healthy volunteers were used as the references. This peptide-based assay system gave sensitivity, specificity, accuracy, and positive and negative predictive values of 100%, 94.6%, 96.2%, 100%, and 88.9%, respectively. Cross reactivity was frequently seen against the sera of fascioliasis (75%) and hookworm infections (50%). Since differential diagnosis between paragonimiasis and fascioliasis can be easily done by clinical presentation and fascioliasis serology, this cross reaction is not a serious problem. Sera from patients with other parasitoses (0-25%) rarely responded to this synthetic antigen. This synthetic peptide antigen seems to be useful for development of a standardized diagnostic system for paragonimiasis.

Molecular detection of Ancylostoma duodenale, Ancylostoma ceylanicum, and Necator americanus in humans in northeastern and southern Thailand

The 2 principal species of hookworms infecting humans are Necator americanus and Ancylostoma duodenale. Case studies on zoonotic hookworm infections with Ancylostoma ceylanicum and/or Ancylostoma caninum are known mainly from Asian countries. Of these 2 zoonotic species, only A. ceylanicum can develop to adulthood in humans. In the present study, we report a molecular-based survey of human hookworm infections present in southern and northeastern Thailand. Thirty larval hookworm samples were obtained from fecal agar plate cultures of 10 patients in northeastren Thailand and 20 in southern Thailand. Partial ITS1, 5.8S, and ITS2 regions of the ribosomal DNA genes were amplified using PCR. The amplicons were sequenced, aligned, and compared with other hookworm sequences in GenBank database. The results showed that, in Thailand, N. americanus is more prevalent than Ancylostoma spp. and is found in both study areas. Sporadic cases of A. ceylanicum and A. duodenale infection were seen in northeastern Thailand.

High prevalence of haplorchiasis in Nan and Lampang provinces, Thailand, proven by adult worm recovery from suspected opisthorchiasis cases

Opisthorchiasis, a risk factor for cholangiocarcinoma in humans, is of public health importance in Thailand. The Annual Surveillance Reports from Nan and Lampang Provinces, Thailand, for the year 2011 showed an opisthorchiasis prevalence of over 70% by recovery of eggs in the feces. This study investigated whether most cases are actually due to minute intestinal flukes (MIF) rather than Opisthorchis viverrini, as the eggs of both can hardly be differentiated by morphology. Fifty and 100 cases from residents in Nan and Lampang, respectively, had stools positive for eggs initially assumed to be those of O. viverrini. Each patient was given praziquantel at 40 mg/kg in a single dose. After 2 hr, 30-45 ml of the purgative magnesium sulfate was given, and stools were collected up to 4 times sequentially. The stools were examined for adult worms by simple sedimentation. It was found that 39 of 50 cases (78.0%) from Nan Province had Haplorchis taichui, with intensities ranging from 5 to 1,250 with an average of 62 worms/case. Taenia saginata (7 cases) and Enterobius vermicularis (1 case) were other helminths recovered as the co-infectants. In Lampang Province, H. taichui was recovered from 69 cases (69.0%). The number of flukes recovered ranged from 1 to 4,277, with an average of 326 worms/case. Four cases had Phaneropsolus bonnei, and 10 T. saginata as the co-infectants. Adult specimens of O. viverrini were not recovered from any stool. Clearly, MIF infection, especially haplorchiasis, is more common in northern Thailand. These findings should encourage the Public Health Office to employ more specific tools than Kato's method for surveillance of opisthorchiasis in Thailand.

Detrimental effect of water submersion of stools on development of Strongyloides stercoralis

Strongyloidiasis is prevalent in Thailand, yet its prevalence in the south is lower than in other parts of the country. This might be due to the long rainy season in the south resulting in stool submersion in water inhibiting worm development. In this study, the effect of water submersion of fecal samples on development of Strongyloides stercoralis was investigated. Ten ml of a 1 ∶ 5 fecal suspension were placed in 15-ml tubes, 35-mm dishes, and 90-mm dishes producing the depths of 80 mm, 11 mm and 2 mm-suspensions, respectively. The worm development was followed at 1/6, 4, 6, 8, 10, 12, 14, 16, 24, and 36 h, by determining the number of filariform larva (FL) generated from agar-plate cultures (APC). Fecal suspensions kept in tubes and 35-mm dishes showed a decline in FL yield relative to incubation time and reached zero production 14 h after incubation. In contrast, the number of FL generated from the suspension kept in 90-mm dishes remained stable up to 36 h. Cumulatively, all tubes and 35-mm dishes became negative in APC after 14 h while 90-mm dishes remained APC-positive up to 36 h. Adding more water or stool suspension to dishes resulted in a decreased number of FL. Mechanical aeration of the suspensions in tubes restored an almost normal FL yield. It appears that the atmospheric air plays a significant role in growth and development of S. stercoralis in the environment and may be one of factors which contribute to a lower prevalence of human strongyloidiasis in the south of Thailand.

The vasculature of nurse cells infected with non-encapsulated Trichinella species

The vasculature surrounding the nurse cells of encapsulated Trichinella spiralis has been described previously. It has been postulated the function of these vessels is to support the growth of the parasite. We describe here for the first time the vasculature surrounding the nurse cells of non-encapsulated T. pseudospiralis and T. papuae. Similar to the vasculature of uninfected muscle cells, the vessels surrounding non-encapsulated Trichinella nurse cells are dense and branched longitudinally along the long axis of the muscle cells; they also appear to be similar in diameter. The netting pattern of enlarged vessels found around T. spiralis (encapsulated) nurse cells is not present in non-encapsulated Trichinella infections. The vessels surrounding non-encapsulated Trichinella nurse cells seem to exist prior to parasite invasion of the muscle cell.

Early detection of Trichinella spiralis in muscle of infected mice by real-time fluorescence resonance energy transfer PCR

Real-time fluorescence resonance energy transfer (FRET) PCR and melting curve analysis using newly developed fluorophore-labeled hybridization probes were applied for the detection of Trichinella spiralis DNA in muscle of mice following oral inoculation with 300 T. spiralis larvae. The developed assay could detect and differentiate T. spiralis, Trichinella papuae, and Trichinella pseudospiralis DNAs by the different melting temperatures (Tm). The assay had a detection limit of 5 × 10(2) positive control plasmid copies, which was equivalent to 1 ng of T. spiralis DNA spiked into 250 mg of muscle sample. No fluorescence signal was detected when the technique was applied to the DNA of 27 parasites other than Trichinella spp. The assay could detect T. spiralis DNA in muscle at 7, 14, and 21 days postinoculation. The range, mean ± standard deviation, and median of the Tm values of all positive muscle tissue samples were 60.4-60.8, 60.6 ± 0.2, and 60.5, respectively. This assay provides an effective tool for the specific, sensitive, and high-throughput detection of T. spiralis DNA in muscle during the early stage of infection. In addition, the technique can be useful for epidemiologic surveillance in naturally infected wildlife.

Molecular evidence of Trichostrongylus colubriformis and Trichostrongylus axei infections in humans from Thailand and Lao PDR

Human trichostrongylosis has been reported in Thailand. Recent reports in Lao People's Democratic Republic concerning species identification urged us to investigate species distribution in Thailand. We report eight human cases in Thailand and Lao People's Democratic Republic that were found to be infected by Trichostrongylus colubriformis and T. axei identified and confirmed by molecular techniques. This evidence is the first molecular evidence of human T. colubriformis and T. axei infection in Thailand. Infection by these two species was apparently epidemic in these areas. It is necessary to proceed with more comprehensive veterinary and epidemiologic studies to enable the practical prevention and control of this parasitic zoonosis.

Differential detection of Trichinella papuae, T. spiralis and T. pseudospiralis by real-time fluorescence resonance energy transfer PCR and melting curve analysis

Trichinellosis caused by nematodes of Trichinella spp. is a zoonotic foodborne disease. Three Trichinella species of the parasite including Trichinella spiralis, Trichinella papuae and Trichinella pseudospiralis, have been etiologic agents of human trichinellosis in Thailand. Definite diagnosis of this helminthiasis is based on a finding of the Trichinella larva (e) in a muscle biopsy. The parasite species or genotype can be determined using molecular methods, e.g., polymerase chain reaction (PCR). This study has utilized real-time fluorescence resonance energy transfer PCR (real-time FRET PCR) and a melting curve analysis for the differential diagnosis of trichinellosis. Three common Trichinella species in Thailand were studied using one set of primers and fluorophore-labeled hybridization probes specific for the small subunit of the mitochondrial ribosomal RNA gene. Using fewer than 35 cycles as the cut-off for positivity and using different melting temperatures (T(m)), this assay detected T. spiralis, T. papuae and T. pseudospiralis in muscle tissue and found the mean T(m) ± SD values to be 51.79 ± 0.06, 66.09 ± 0.46 and 51.46 ± 0.09, respectively. The analytical sensitivity of the technique enabled the detection of a single Trichinella larva of each species, and the detection limit for the target DNA sequence was 16 copies of positive control plasmid. A test of the technique's analytical specificity showed no fluorescence signal for a panel of 19 non-Trichinella parasites or for human and mouse genomic DNA. Due to the sensitivity and specificity of the detection of these Trichinella species, as well as the fast and high-throughput nature of these tools, this method has application potential in differentiating non-encapsulated larvae of T. papuae from T. spiralis and T. pseudospiralis in tissues of infected humans and animals.

Molecular identification of Trichinella papuae from a Thai patient with imported trichinellosis

Previously, we reported the presence of imported trichinellosis in a Thai worker returning from Malaysia, who presented with progressive generalized muscle hypertrophy and weakness after eating wild boar meat. This work analyzed a partial small subunit of a mitochondrial ribosomal RNA gene of Trichinella larvae isolated from the patient. The results showed complete identity with a mitochondrial RNA gene of Trichinella papuae (GenBank accession no. EF517130). This is the first report of imported trichinellosis in Thailand caused by T. papuae. It is possible that T. papuae is widely distributed in the wildlife of Southeast Asia.

Current status of the research ethics committees in Thailand

BACKGROUND

Many research ethics committees (RECs) have been established to review biomedical research involving human subjects in many research institutes. The purpose is "To protect rights and welfare of human research participants". It is necessary to determine how many research ethics committees have been established in Thailand and whether they have a high enough standard toprotect the rights and welfare of human research subjects.

OBJECTIVE

To determine the status of research ethics committees in Thailand.

MATERIAL AND METHOD

One hundred thirty survey questionnaires were distributed by mail to medical schools of universities, public hospitals under the Ministry of Public Health, private hospitals, and research institutes.

RESULTS

Seventy-eight questionnaires were returned. Thirty respondents had standard Operating Procedures (SOP). Twenty-two RECs had their own office while 36 had to share the office with other departments or units. Board meeting frequency was once a month. The average number of committee members was 14 and the majority was scientific members. Absence of nonaffiliated members was found in RECs (20.6%). Thirty RECs had never provided training for REC members and investigators, the other 48 provided training at least once a year Decision are made by consensus in 51 and majority vote in 14 RECs. Twenty-two respondents managed conflicts of interest (COI) by asking those members to leave the meeting before a decision was finalized. Thirty-nine RECs required continuous review after approval of the protocols.

CONCLUSION

Strong support from the organization leader is a key factor to efficiency and high standards of REC operation. Developing a network of RECs will be useful for future development. REC members still need knowledge to better protect the rights, safety, and well-being of research participants.

An enzyme-linked immunosorbent assay as screening tool for human intestinal capillariasis

Human intestinal capillariasis caused by Capillaria philippinensis is characterized by chronic diarrhea which may lead to death if left untreated. The mortality is highest among patients who are negative by conventional stool examination. Therefore this study explored the application of an enzyme-linked immunosorbent assay (ELISA) as a screening test for human intestinal capillariasis. The ELISA was developed using Trichinella spiralis soluble antigen for the detection of antibodies against C. philippinensis. A cut-off level at the upper 99% limit of the absorbance values of the healthy controls was established for positivity. All intestinal capillariasis sera showed positive ELISA, demonstrating 100% sensitivity, while all healthy control sera gave absorbance values below the cut-off level, resulting in 100% specificity. The ELISA was also positive with 75% of trichinellosis, 13.9% of strongyloidiasis, 9.1% of trichuriasis, and 4.2% of opisthorchiasis sera. The ELISA and immunoblot were in agreement in 91.1% of the sera tested. It was suggested that the here-presented ELISA is capable to detect intestinal capillariasis cases in endemic areas whose coproscopy is negative for worm eggs, larvae or adults.

Evaluation of IgG4 and total IgG antibodies against cysticerci and peptide antigens for the diagnosis of human neurocysticercosis by ELISA

To support the clinical diagnosis of human neurocysticercosis (NCC), we evaluated two peptides, HP6-3 and Ts45W-1, as well as crude saline extract (SE) of Tenia solium cysticerci as antigens for the detection of specific IgG4 subclass and total IgG antibodies by an enzyme-linked immunosorbent assay (ELISA). The sera of definitive diagnosed NCC patients, patients infected with other parasitoses and healthy controls were examined. The diagnostic sensitivity for IgG4 and total IgG detection of the ELISA against SE antigen was 100% and 64.3% with a high amount of cross-reactions to taeniasis saginata at 88.9% (8/9) and 100% (9/9), respectively. The SE-based IgG4-ELISA showed the highest specificity (80.9%). Both peptide-based IgG4-ELISAs provided a superior sensitivity (78.6%) to the total IgG tests whereas their specificity was 66.7% for HP6-3 and 69.8% for Ts45W-1 only. The SE-based ELISA for the detection of specific IgG4 antibody can be used for the diagnosis of neurocysticercosis as well as for serological surveys of NCC endemic areas. The peptide-based IgG4 ELISAs potentially provide a reliable and cost effective alternative method independent from live parasite supply.

Hypereosinophilia and abdominopulmonary gnathostomiasis

A 16-year-old Thai male presented with sudden onset severe epigastric and right upper quadrant pain, fever (39 degrees C), chills and malaise. He gave no history of underlying disease, migratory swelling or urticarial skin rash. He had a history of frequently eating raw pork. Physical examination revealed a soft abdomen with markedly tender hepatomegaly. His blood count showed extreme leukocytosis with hypereosinophilia. After admission he developed a non-productive cough with left sided chest pain, a chest x-ray showed a left pleural effusion. Serological findings were positive for Gnathostoma larval antigen but not Fasciola antigen. The patient recovered completely after albendazole treatment. His clinical presentation is compatible with abdominopulmonary hypereosinophilic syndrome or visceral larva gnathostomiasis. The presented case is interesting not only for physicians who work in endemic areas of gnathostomiasis but also for clinicians who work in travel medicine clinics in developed countries, to consider abdominopulmonary gnathostomiasis when patients present with the signs and symptoms of visceral larva migrans.

The epidemiology of Dirofilaria immitis infection in outpatient dogs at Chiang Mai University Small Animal Hospital, Thailand

Five hundred eighty-nine dog blood samples from the small animal hospital of Chiang Mai University were examined for Dirofilaria immitis prevalence using a microhematocrit tube technique for microfilaria detection. In parallel, a once a month follow-up study on 36 D. immitis negative dogs was conducted to detect the time of acquiring infection in each animal. The diagnostic criteria for the incidence study was based on microfilaria detection or on positive findings against D. immitis antigen using the Witness commercial kit. The estimated prevalence was 18.2% (15-21%; 95% CI). There was no statistical difference between male and female infection rates. The age-specific prevalence of dogs under 2 years old was 6.4%, which was lower than the 2-4 year old group and all the other age groups at a 95% confidence level. In older dogs the prevalence reached 41.5%. Most of the dogs housed outdoors had a statistically higher infection rate than the dogs housed indoors (chi-square = 9.662, 1 df, p = 0.002). Only 109 dogs received chemoprophylaxis resulting in a significantly lower infection rate than in the non-heartworm prevention dogs (chi-square =14.424, 1 df, p = 0.000). The overall incidence density and the incidence during the rainy, cool and hot seasons were 5.2, 6.9, 3.5, and 2.7 animals per 100 animal-months, respectively. The incidence rate ratio between wet/dry, rainy/cool, rainy/summer, and cool/hot seasons were 2.18, 1.98, 2.59 and 1.30, respectively. The 95% confidence interval revealed no difference among seasons. In conclusion, dogs in D. immitis endemic northern Thailand contract infection in about 2 years.

Cystic echinococcosis in Thailand with a special note on detection by serology in one family

Thailand is a nonendemic area of echinococcosis. We report, herein, 3 cases with a special note on the use of serology in detection of the disease in one family. All cases were Thais. The first case was a man, having a cystic mass in the liver. He was subsequently diagnosed as having echinococcosis following positive serology. The second case, a male, had a renal hydatid cyst revealed by histopathology, and a positive serological test. The third case, a wife of case 2, was positive by serological screening for echinococcosis and subsequently proven to have splenic and liver echinococcal cysts. The present findings support the use of serology in the case detection of echinococcosis in Thailand.

Albendazole therapy for eosinophilic meningitis caused by Angiostrongylus cantonensis

Eosinophilic meningitis in humans is commonly caused by the nematode Angiostrongylus cantonensis. A severe headache is the most common presenting symptom. A prospective, randomized, double-blind, placebo, controlled study was conducted to determine if albendazole was efficacious in relieving such headaches. Seventy-one patients (36 and 35 in the treatment and control groups) were enrolled in the study. Five patients (two and three in the treatment and control groups) were excluded from the study because of being lost to follow-up, and the clinical data were incomplete. Therefore, 34 and 32 patients in the treatment and control groups were studied, respectively. Albendazole was administered at 15 mg/kg/day or identical placebo for 2 weeks. The number of patients with persistent headaches after 2 weeks was 7 and 13 in the albendazole and placebo groups (p = 0.08), respectively. The mean duration of a headache was 8.9 and 16.2 days in the albendazole and placebo groups, respectively (p = 0.05). No serious drug events were observed. A 2-week course of albendazole appeared to reduce the duration of headache in eosinophilic meningitis.

Potential use of Trichinella spiralis antigen for serodiagnosis of human capillariasis philippinensis by immunoblot analysis

Intestinal capillariasis is an emerging helminthic zoonosis caused by Capillaria philippinensis and is frequently fatal if not diagnosed correctly. The present study demonstrates cross-reactivity between Trichinella spiralis larval antigens and C. philippinensis-infected human sera by immunoblotting. Sera from 16 proven intestinal capillariasis patients and 16 proven trichinosis patients were tested. The antigenic patterns recognized by intestinal capillariasis sera varied with the molecular masses, ranging from less than 20.1 to more than 94 kDa. The immunoblotting profiles of the trichinosis sera were similar to those of the intestinal capillariasis sera. The antigenic bands with 100% reactivity were located at 36.5, 40.5, and 54 kDa, respectively. Sera from patients with trichuriasis, strongyloidiasis, opisthorchiasis, and healthy controls differed clearly from the previous two and produced very faint patterns of reactivity and attenuated bands. This assay is potentially useful for large-scale screenings of persons at risk for C. philippinensis infection. Parasitological stool examinations of the positive cases are necessary as second-tier laboratory tests for confirming the diagnosis.

Comparison of the quantitative formalin ethyl acetate concentration technique and agar plate culture for diagnosis of human strongyloidiasis

The quantitative formalin ethyl acetate concentration technique (QFEC) was compared to agar plate culture (APC) for the detection of Strongyloides stercoralis larvae. QFEC could substitute for APC only when the parasite load was higher than 50 larvae per g of stool. This study serves as a good reminder to those conducting stool exams about the sensitivity and specificity limitations of both techniques.

Differential diagnosis of Taenia saginata and Taenia saginata asiatica taeniasis through PCR

New multiplex-PCR and PCR-linked restriction fragment length polymorphism protocols, derived from Taenia saginata HDP2 DNA sequence, have been designed that allow the simultaneous and specific identification of T. saginata and Taenia saginata asiatica. Proglottids expelled from 20 different Spanish taeniasis patients, previously diagnosed as T. saginata by both morphological identification and multiplex HDP2-PCR, were also examined by the newly developed PCR protocols, and the original diagnosis of T. saginata infection was confirmed. All of the 20 T. saginata samples were negative in the T. saginata asiatica-specific PCR. Three authentic T. saginata asiatica samples were unambiguously identified as such in the T. saginata asiatica PCR. These new protocols have immediate potential for the specific, sensitive, and rapid identification of T. saginata asiatica and may assist in taxonomic studies.

Evaluation of crude antigen of Dirofilaria immitis third-stage larva for detection of antibody against Wuchereria bancrofti infection by indirect ELISA

Dirofilaria immitis is an important heart worm in dogs. An immunodiagnostic test is frequently applied to use an alternative antigen from other parasites. A crude antigen from infective third stage larva (L3) of D. immitis was employed in detecting the antibody to Bancroftian filariasis in humans by indirect ELISA. It was shown that 25 cases of Bancroftian filariasis (76%) at a cut-off value of 0.230, were positive. Cross-reactivity was tested using available sera of other helminthic infections. These sera were 47% (23/49) positive. They comprised a major intestinal helminthic infection, 7 from 15 (46%) strongyloidiasis sera, none from 5 (0%) hookworm infection sera, 6 from 10 (60%) trichinosis sera, 2 from 10 (20%) cysticercosis sera and 8 from 9 (88%) gnathostomiasis sera. The mean OD of sera from Bancroftian filariasis patients was not significantly different from that of the other helminthic infections (p>0.05). In this study, crude antigen may be valuable for the serodiagnosis of Wuchereria bancrofti when subjects do not have tissue helminth infections. However, the crude antigen should be purified to obtain a better sensitivity and specificity of the test.

Production of monoclonal antibodies to the cuticle of advanced third-stage larva of Gnathostoma spinigerum

This study has demonstrated that sera from Balb/c mice infected with live advanced third-stage larvae (aL3), but not those immunized with crude larval extract, immunoprecipitated the 25-kDa protein from surface-iodinated extract of aL3. Hybridoma cell lines derived from spleen cells of an infected mouse secreted antibodies that reacted with several tissue of aL3 including the esophagus, intestine, muscle and cuticle by immunofluorescence assay. However, none of the cuticle-positive hybridoma cell lines produced antibodies that recognized surface-iodinated protein of aL3 by immunoprecipitation. Western blot analysis showed that monoclonal antibodies (MAbs) secreted by clones derived from one of the cuticle-positive hybridoma lines recognized proteins of molecular weights ranging from 55-96 kDa. The MAbs most likely reacted with the collagenous component of the cuticle.

Molecular cloning of a gene encoding matrix metalloproteinase-like protein from Gnathostoma spinigerum

The advanced third-stage larvae (aL3) of Gnathostoma spinigerum contain a 24 kDa glycoprotein with diagnostic potential. Immunoscreening with the monoclonal antibody to the 24-kDa protein (mAb GN6/ 24) has identified a cDNA clone with an insert of 932 base pairs (bp). The insert contains a full-length gene of 732 bp encoding a protein that is 33-39% similar to matrix metalloproteinases (MMPs) of Caenorhabditis elegans and several lower and higher vertebrates. The MMP-like protein of G. spinigerum possesses the catalytic domain, but lacks the propeptide and hemopexin-like domains found in other MMPs. A signal peptide of 23 amino acids at its amino terminus indicates that it is a secretory protein, which is confirmed by Western blot analysis showing the presence of the 24 kDa protein in the excretory-secretory products of aL3.

Lack of efficacy of quinine and artemether against advanced third-stage larvae of Gnathostoma spinigerum in vitro

The efficacy of quinine and artemether--the effective blood schizontocide in malarial treatment--has been in vitro tested with the advanced third-stage larvae of Gnathostoma spinigerum. All larvae were collected from freshwater eel (Fluta alba) and exposed to the culture medium, each containing either quinine dihydrochloride or artemether at a final concentration of 20 microg/ml and 0.5 microg/ml, respectively for 21 consecutive days. Larval motility was assessed daily and the topographical changes were assessed using scanning electron microscope after 21-days of drug exposure. All worms moved actively for 21 days of study period and no change in surface ultrastructure was observed. Quinine and artemether at these concentrations have no effect on movement and topographical changes on the advanced third-stage larvae of this parasite.

Gnathostoma spinigerum: analysis of protein patterns by two dimensional gel electrophoresis

The protein extracts from male (MS) and female (FS) adults and advanced third-stage larvae (LS) of Gnathostoma spinigerum were separated by high resolution two-dimensional gel electrophoresis (2-DE). The polypeptide spots, as detected by silver staining, were subsequently identified. The spot patterns of LS, MS and FS were highly complex and consisted of more than 75, 44, 52 prominent spots, respectively. In addition, the stage-specific protein patterns were identified. This 2-DE database should provide an important reference for future biological and biochemical studies of G. spinigerum.

Antigenic components of Gnathostoma spinigerum recognized by infected human sera by two-dimensional polyacrylamide gel electrophoresis and immunoblotting

Antigenic components of Gnathostoma spinigerum larval extract were revealed by two-dimensional gel electrophoresis (2-DE) and immunoblot analysis using sera from patients with 6 proven cases of gnathostomiasis, 5 presumptive cases of gnathostomiasis, 3 proven cases of angiostrongyliasis, 3 proven cases of cysticercosis, and pooled sera from healthy adults. By the 2-DE, the larval extract was highly complex and consisted of more than 75 polypeptides. Immunoblotting analysis of this larval extract after reaction with each of 6 proven gnathostomiasis sera revealed various numbers of antigenic spots ranging from 30 to 70 spots at the approximate molecular masses of less than 14.4 to more than 94 kDa with isoelectric points (pI) of less than 4.65 to 9.6. Antigenic spots at the approximate molecular mass of more than 30 kDa were recognized with the proven angiostrongyliasis, proven cysticercosis and healthy control sera but these sera did not react with the spots at approximate molecular masses of 23-25 kDa with pI of 8.3-8.5. The reacted spots, which consisted of at least 1 to 2 spots, were unique for the recognition of gnathostomiasis sera. Five out of 6 (83.3%) proven and 4 out of 5 (80%) presumptive gnathostomiasis sera reacted with these specific spots.

Recognition of deglycosylated larval proteins of Gnathostoma spinigerum by a monoclonal antibody and human gnathostomiasis antiserum

The study on the recognition of 35S-labelled somatic antigens of Gnathostoma spinigerum advanced third-stage larva (aL3) has revealed that the mAb GN6/24 immunoprecipitated 26- and 24-kDa proteins from the undigested and N-glycosidase F-digested larval extracts, respectively. The recognition of the deglycosylated form of the glycoprotein indicated that the mAb reacted with the peptide epitope on the 26-kDa protein. Human gnathostomiasis antiserum immunoprecipitated most of the N-glycosidase F-digested larval proteins including the deglycosylated 26-kDa protein.

Fluctuations of larval excretion in Strongyloides stercoralis infection

Follow-up stool examinations were carried out on two groups of the subjects who were screened negative (group 1) or positive (group 2) for Strongyloides stercoralis by the agar plate culture. This technique could detect S. stercoralis larvae in 87.5-96.4% of the subjects in group 2 and 0-5.9% of the subjects in group 1 on various days of the eight-week and four-week follow-up periods, respectively. The detection rate on each day of examination was not statistically different from that on the first day in both groups. Quantitative measurement of S. stercoralis larvae excreted in the feces of the subjects in group 2 by the standard direct smear method of Beaver and others revealed slight to marked fluctuations of the larval output in individual subjects. From the results of both stool examination methods, it could be implied that 52% of S. stercoralis-infected individuals had low-level infection.

Movability of advanced third-stage larva of Gnathostoma spinigerum exposed to albendazole sulphoxide in vitro

Movability of advanced third-stage larvae of Gnathostoma spinigerum exposed to albendazole sulphoxide (AlbSO), the active metabolite of albendazole, was determined in vitro. Larvae in control groups moved actively with the whole body for all 21 days of the study period. In larvae treated with AlbSO 1 microg/ml, the movement was significantly reduced after 11 days exposed to the drug and to be only a part of body on the 15th-21st days. In larvae treated with AlbSO 2 microg/ml, the movement was initiated in decreasing after 9th days and to be only a part of body on the 12th-17th days. Finally, worms were immobile but not dead on the 20th-21st days. Although there was no larvae died at 21st days exposed to AlbSO in both concentrations; but all worms were sluggish and may die later. These lethargic worms may not be able to migrate in patients and leading to cure. Albendazole may not be benefit for acute symptom clearance; however, it can prevent the recurrent migratory swelling after the treatment of 21 day-course.

Specific gravity of Opisthorchis viverrini eggs

The specific gravity of the eggs of the liver fluke Opisthorchisviverrini was determined using a sucrose gradient centrifugation and found to range from 1.2713 to 1.3043. The peak egg count was located at the sucrose fraction with a specific gravity of 1.2814. An attempt to float eggs in saturated sodium nitrate solution, sp.gr. 1.4, failed. Examination of human stool specimens for Oviverrini eggs by simple flotation in saturated sodium nitrate solution and the formol-ether sedimentation technique revealed that the flotation technique was not as efficient as the sedimentation technique. It was suggested that the flotation techniques were inappropriate for the detection of Oviverrini eggs in faeces or contaminated soil.

Indirect haemagglutination test using monoclonal antibody-affinity purified antigens for diagnosis of human paragonimiasis due to Paragonimus heterotremus

An indirect haemagglutination test (IHA) using antigens purified by monoclonal antibody-affinity chromatography was developed for the diagnosis of human paragonimiasis caused by Paragonimus heterotremus. Sera from patients with paragonimiasis (n = 30) were evaluated, along with sera from other parasitic infections (n = 92), pulmonary tuberculosis (n = 18) and healthy controls (n = 30). The sensitivity, specificity as well as positive and negative predictive value of the IHA, calculated at the prevalence of disease at 17.6%, were all 100%.

Detection of Paragonimus heterotremus in experimentally infected cat feces by antigen capture-ELISA and by DNA hybridization

An antigen capture enzyme-linked immunosorbent assay (antigen capture-ELISA) and DNA hybridization technique were developed and evaluated for their application in the detection of Paragonimus heterotremus infection in experimentally infected cats. An IgG fraction prepared from serum of a rabbit immunized with P. heterotremus excretory-secretory (ES) products was used as the capture antibody. An IgG1 monoclonal antibody specific to the 22- and 31.5-kDa ES products of P. heterotremus was used as the antigen probe. As little as 0.24 ng of the ES products could be detected by this technique. A specific P. heterotremus DNA probe derived from the P. heterotremus genomic DNA library containing 1,500 base pairs was used in a dot-blot hybridization assay for the detection of parasite DNA. The radioactively labeled probe could detect DNA released from as few as 2 P. heterotremus eggs. Both ELISA and DNA hybridization were found to have 100% specificity, with sensitivities of 73.7% and 100%, respectively.

A dot-ELISA test using monoclonal antibody-purified antigens for the diagnosis of paragonimiasis caused by Paragonimus heterotremus

A dot enzyme-linked immunosorbent assay (dot-ELISA) using antigens purified by monoclonal antibody-affinity chromatography was developed for detecting antibodies to Paragonimus heterotremus in four groups of subjects. They consisted of 30 patients with P. heterotremus infection, 93 patients with other parasitic infections, 18 patients with pulmonary tuberculosis and 30 normal, healthy controls. Sensitivity, specificity, as well as positive and negative predictive values of the test were 100, 97, 88, and 100%, respectively.

Monoclonal antibodies to Paragonimus heterotremus and their potential for diagnosis of paragonimiasis

Monoclonal antibodies (MAbs) specific to the lung fluke (Paragonimus heterotremus) were produced against the soluble metabolic products (excretory-secretory antigen). Three hybrids secreting MAbs specific for P. heterotremus antigens were identified by an indirect enzyme-linked immunosorbent assay (ELISA) against a panel of homologous and 24 heterologous parasite antigens and Mycobacterium tuberculosis. Of the three specific clones, clone 10F2, which was IgG1 producing and which gave immune complex bands with 31.5-kD and 22-kD polypeptides by gel electrophoresis and immunoblotting, was selected for further characterization and evaluation of its possible diagnostic potential. The result obtained from an indirect immunofluorescent antibody test suggested that MAb 10F2 reacted with mucosa and contents of the worm's intestine. The antibody could be readily used to prepare an affinity-purified antigen for use in an indirect ELISA that was highly sensitive and specific for the detection of circulating antibody in sera of paragonimiasis patients.

Growth and development of Gnathostoma spinigerum early third-stage larvae in vitro

Early third-stage larvae of Gnathostoma spinigerum were cultured in RPMI-1640 supplemented with 25mM NaHCO3,100 units/ml penicillin G, 100 microg/ml of streptomycin, 5 microg/ml of amphotericin B and 10% foetal calf serum at 37 degrees C under 5% CO2 in air for 60 days. After 3 days of cultivation, the larvae moulted. Body sizes increased from 0.49 +/- 0.09 x 0.07 +/- 0.01 mm in length and width to 4.08 +/- 0.48 x 0.32 +/- 0.04 mm after 60 days of cultivation. The maximum body length and width of these larvae were 4.94 mm and 0. 35 mm, respectively. The survival rate (67.5 %) of the worms was observed at the end of cultivation. The addition of foetal calf serum was found to be essential for growth and development.

Detection of circulating Trichinella spiralis larvae by polymerase chain reaction

Several investigators have successfully applied the polymerase chain reaction to the amplification of DNA from Trichinella spiralis muscle-stage larvae. We show herein that specific DNA can be amplified from T. spiralis migratory larvae in the blood of experimentally infected mice. The polymerase chain reaction detected the presence of migratory larvae in mouse blood from day 5 to day 14 of infection. The technique may be applied to human trichinosis, but its diagnostic value will depend on the severity and stage of the infection.