The biology of Aspiculuris tetraptera Schultz (Nematoda, Oxyuridae)

The following results of field observations and laboratory experiments conducted during a study of the biology of Aspicufuris tetraptera are presented: a) Sex-resistance and age resistance were demonstrated in a survey of the incidence of A. tetraptera in wild populations of its natural host, Mus musculus. Concurrent infection with, Syphacla obvelata was not detri-mental to either parasite. b) Soon after infection the larvae of A. tetraptera became established in the Crypts of Lieberkuhn in the mid-colon, undertook an anterior emigration on day 7 and thereafter persisted, in the anterior colon, where the infection became patent on day 26. c) It was discovered, that mice resisted infection by rejecting up to 80% of the worm burden before day 20. d) This response was stronger in female mice than in males, consequent (it is suggested) to the immunosuppressive properties of testosterone. e) It is proposed that a different response accounted for the earlier termination, of infections in rats and Apodemus sylvaticus. f) nice acquired immunity to A. tetraptera, which could be elicited by the: crypt phase alone. g) Hydrocortisone was effective in suppressing immunity. It was suggested, that drug-induced tolerance may have been involved. h) Methotrexate delayed immunity, but retarded worm growth. I) Specific precipitating antibody was studied and it was proposed that two classes of antibody were involved, tentatively identified as IgG-and Igm. j) A procedure for transplanting worms from, donor to recipient mice was developed and the following observations were, made: i/ 7 day larvae evoked immune expulsion suppressible by hydrocortisone and methotrexate, ii/ larvae were expelled faster from, immune mice than from controls, iii/ "Damaged" larvae were also more rapidly rejected but survived in hydrocortisone treated or in irradiated recipients, iv/ mature worms; survived for 85 days, senescence accounting for their eventual disappearance. v/ Mature worms survived, in immune recipients, vi/ Mature worms evoked antilarval immunity but were themselves not affected by it. Concurrent; infection with Trichuris muris was detrimental to A. tetraptera. I) The results are; discussed in the context of current research in parasitology, m) It is suggested that A. tetraptera would prove a good model for future work.<p

Distribution of Giardia duodenalis (Assemblages A and B) and Cryptosporidium parvum amongst migrant workers in Peninsular Malaysia

The influx of low skilled workers from socioeconomically deprived neighbouring countries to Malaysia has raised concerns about the transmission of communicable gastrointestinal diseases such as giardiasis and cryptosporidiosis to the local population. Therefore, a cross sectional study was conducted to investigate the prevalence of both diseases and the genetic diversity of these pathogens in the migrant population. Microscopic examination of faecal samples from 388 migrant workers involved in five working sectors were screened and 10.8% (n = 42) were found to be positive with Giardia spp. and 3.1% (n = 12) with Cryptosporidium spp. infections. PCR amplicons at the triosephosphate isomerase (tpi) gene were successfully obtained for Giardia duodenalis from 30 (30/388; 7.73%) samples with assemblages AII and B in 13 (13/30; 43.3%) and 17 (17/30; 56.7%) positive samples, respectively. Nine samples (9/388; 2.3%) were identified as Cryptosporidium parvum using PCR-RFLP analysis. Country of origin, duration of residence in Malaysia and working sectors significantly influenced G. duodenalis assemblage AII infections amongst the targeted population. Meanwhile, C. parvum infection was significantly associated with those working in the food service sector. Despite the low presence of pathogenic G. duodenalis and C. parvum in the study population, the results highlight the risk of anthroponotic foodborne and waterborne transmission and therefore call for implementation of control strategies through improvements in personal hygiene and sanitation standards

Characterization of NontyphoidalSalmonellaIsolates from Asymptomatic Migrant Food Handlers in Peninsular Malaysia

Asymptomatic Salmonella carriers who work as food handlers pose food safety and public health risks, particularly during food preparation, and this has serious implications for the disease burden in society. Therefore, we conducted a study to determine the number of Salmonella carriers in a migrant cohort in several food establishments in three major cities in Peninsular Malaysia. Sociodemographic data and stool samples were collected and analyzed using standard methods of detection and isolation. Antimicrobial susceptibility tests of the positive samples were also performed. A total of 317 migrant food handlers, originating from South and Southeast Asian countries, were recruited voluntarily. Nine (2.8%) stool samples were confirmed to be Salmonella positive. PCR serotyping and pulsed-field gel electrophoresis identified four serotypes as Typhimurium (n = 3), Corvallis (n=2), Hadar (n=1), Agona (n=1) and two unknown serovars. Antimicrobial susceptibility tests revealed that all nine isolates were susceptible to amoxicillin-clavulanic acid, cefotaxime, ceftazidime, ceftriaxone, and gentamycin. However, seven isolates were found to be multidrug resistant to ampicillin, chloramphenicol, trimethoprim-sulfamethoxazole, sulfonamides, streptomycin, and tetracycline. This study highlights that carriers of nontyphoidal Salmonella exist among migrant food handlers, which poses a health risk to consumers through food contamination. Our results indicate a need for authorities to enhance food safety awareness in the migrant workers and to reevaluate current health screening methods to include preventive measure such as mandatory stool screening as part of the preemployment and routine health examinations

Entamoeba infections and associated risk factors among migrant workers in peninsular Malaysia

The influx of low skilled migrant workers to Malaysia from low socio-economic countries where gastrointestinal parasitic infections are prevalent has raised concerns about transmission to the local population. Three methods for detection (serology, microscopy and molecular techniques) were utilized to identify Entamoeba infections amongst the targeted cohort and determine risk factors associated with infection. Serological screening of 484 migrant workers from five working sectors in Peninsular Malaysia using IgG4 ELISA based on the rPPDK antigen showed an overall seroprevalence of 7.4% (n = 36; CL95 = 5.3–10.1%) with only one factor statistically associated with seropositivity of anti-amoebic antibodies, i.e. years of residence in Malaysia (χ21 = 4.007, p = 0.045). Microscopic examination of 388 faecal samples for protozoan cysts and trophozoites showed a slightly higher prevalence (11.6%; n=45; CL95: 8.4–14.8%). Meanwhile, amplification of the 16S rDNA gene detected two species i.e. Entamoeba dispar (23/388; 5.9%; CL95: 3.6–8.3%) and E. histolytica (11/388; 2.8%; CL95: 1.2–4.5%) and mixed infections with both parasites in only three samples (3/388; 0.8%; CL95: 0.2–2.2%). Entamoeba dispar infection was significantly associated with those employed in food and domestic services (χ24 = 12.879, p = 0.012). However, none of the factors affected the prevalence of E. histolytica infection. Despite the low prevalence of E. histolytica in faecal samples of the study cohort, the presence of this pathogenic parasite still poses potential public health risks and calls for tighter control strategies based on better availability of chemotherapeutic treatment and accessibility to appropriate health education. © 2019, Malaysian Society for Parasitology. All rights reserved

Epidemiology and immunodiagnostics of Strongyloides stercoralis infections among migrant workers in Malaysia

To investigate the status of Strongyloides(S.) stercoralis infections among migrant workers in Malaysia for the first time and identify risk factors. Methods: Four diagnostic methods were employed for the detection of S. stercoralis including microscopy, enzyme-linked immunosorbent assay (ELISA) using a commercial kit, ELISA using the rSs1a antigen and polymerase chain reaction (PCR). Low and semi-skilled workers from five working sectors (i.e. manufacturing, food service, agriculture and plantation, construction and domestic service) were tested on a voluntary basis. Results: The overall seroprevalence of S. stercoralis from 483 workers employing the ELISA commercial kit for IgG was 35.8% (n=173; 95% CI: 31.5%-40.1%) whereas seroprevalence using the rSs1a-ELISA was 13.0% (n=63; 95% CI: 10.0%-16.0%). Cross tabulation between the ELISA commercial kit and rSs1a-ELISA showed that only 6.4% (n=31; 95% CI: 4.2%-8.6%) of the samples were positive in both tests. Microscopic examination of all 388 fecal samples were negative; however subsequent testing by a nested PCR against DNA from the same samples successfully amplified DNA from three male subjects (0.8%; 3/388). Male workers, India and Myanmar nationality, food service occupation and those living in the hostel were statistically significant with seroprevalence (P<0.005). Conclusion: This is the first report on the epidemiology of S. stercoralis infections among the migrant workers in Malaysia. Our results highlight the importance of using appropriate diagnostic tools for detection. The presence of anti-S. stercoralis antibodies in the study population calls for improvements in personal hygiene and sanitation standards among migrant workers in Malaysia through control strategies including health education campaigns and programs aimed at increasing awareness and healthy behaviors. © 2019 Asian Pacific Journal of Tropical Medicine Produced by Wolters Kluwer-Medknow. All rights reserved