The Angiostrongylus lungworms are of public health and veterinary concern in many countries. At the family level, the Angiostrongylus lungworms have been included in the family Angiostrongylidae or the family Metastrongylidae. The present study was undertaken to determine the usefulness and suitability of the nuclear 18S (small subunit, SSU) rDNA sequences for differentiating various taxa of the genus Angiostrongylus, as well as to determine the systematics and phylogenetic relationship of Angiostrongylus species and other metastrongyloid taxa. This study revealed six 18S (SSU) haplotypes in A. cantonensis, indicating considerable genetic diversity. The uncorrected pairwise 'p' distances among A. cantonensis ranged from 0 to 0.86%. The 18S (SSU) rDNA sequences unequivocally distinguished the five Angiostrongylus species, confirmed the close relationship of A. cantonensis and A. malaysiensis and that of A. costaricensis and A. dujardini, and were consistent with the family status of Angiostrongylidae and Metastrongylidae. In all cases, the congeneric metastrongyloid species clustered together. There was no supporting evidence to include the genus Skrjabingylus as a member of Metastrongylidae. The genera Aelurostrongylus and Didelphostrongylus were not recovered with Angiostrongylus, indicating polyphyly of the Angiostrongylidae. Of the currently recognized families of Metastrongyloidea, only Crenosomatidae appeared to be monophyletic. In view of the unsettled questions regarding the phylogenetic relationships of various taxa of the metastrongyloid worms, further analyses using more markers and more taxa are warranted.
A new genus of the Monogenea, Teraplectanum n. g., is proposed for two new species of diplectanids found on the gills of Terapon theraps Cuvier collected off Carey Island, Peninsular Malaysia. The genus is based on a unique arrangement of the male reproductive system. In the new species spermatozoa stored in the seminal vesicle and secretions stored in the prostatic reservoir are transferred into, and mixed to form semen within, a special sclerotized auxiliary piece (SAP), and not within the copulatory tube as occurs in the majority of monogeneans. Teraplectanum species also possess a unique sclerotized vaginal loop through which the vaginal tube passes en route from the vaginal pore to the seminal receptacle. The two new species are Teraplectanum crassitubus n. sp. (type species) and T. angustitubus n. sp. They differ from each other mainly in the morphology of their copulatory tube: in T. crassitubus, the proximal region of this tube is thicker compared to the slender proximal region in T. angustitubus, although in both cases the tube tapers and twists distally. Of the known diplectanid species, only Diplectanum undulicirrosum Zhang et al., 2000 (currently considered incertae sedis) possesses such sclerotized hard parts, which suggests the same type of arrangement of the male reproductive system. Consequently, D. undulicirrosum is re-assigned to this new genus as Teraplectanum undulicirrosum (Zhang et al., 2000) n. comb. The copulatory tube of T. undulicirrosum is similar to the slender, undulating copulatory tube of T. angustitubus but does not taper distally as in the latter species.
Soil contaminated with helminth eggs and protozoan cysts is a potential source of infection and poses a threat to the public, especially to young children frequenting playgrounds. The present study determines the levels of infection of helminth eggs in soil samples from urban and suburban playgrounds in five states in Peninsular Malaysia and identifies one source of contamination via faecal screening from stray animals. Three hundred soil samples from 60 playgrounds in five states in Peninsular Malaysia were screened using the centrifugal flotation technique to identify and determine egg/cyst counts per gram (EPG) for each parasite. All playgrounds, especially those in Penang, were found to be contaminated with eggs from four nematode genera, with Toxocara eggs (95.7%) the highest, followed by Ascaris (93.3%), Ancylostoma (88.3%) and Trichuris (77.0%). In addition, faeces from animal shelters were found to contain both helminth eggs and protozoan cysts, with overall infection rates being 54% and 57% for feline and canine samples, respectively. The most frequently occurring parasite in feline samples was Toxocara cati (37%; EPG, 42.47 ± 156.08), while in dog faeces it was Ancylostoma sp. (54%; EPG, 197.16 ± 383.28). Infection levels also tended to be influenced by season, type of park/playground and the texture of soil/faeces. The occurrence of Toxocara, Ancylostoma and Trichuris eggs in soil samples highlights the risk of transmission to the human population, especially children, while the presence of Ascaris eggs suggests a human source of contamination and raises the issue of hygiene standards and public health risks at sites under investigation.
Ligophorus belanaki n. sp. and Ligophorus kederai n. sp. are described from Liza subviridis Valenciennes, 1836 and Valamugil buchanani Bleeker, 1854, respectively. Ligophorus kederai n. sp. has fenestrated ventral anchors, while in L. belanaki n. sp. the ventral anchor is not fenestrated. Ligophorus belanaki n. sp. is similar to L. careyensis, one of its coexisting congeners, in the overall shape and size of hard parts, but differs in having a flat median piece in the structure of the AMP (antero-median protuberance of the ventral bar), copulatory organ with non-ornamented initial part and longer vaginal tube, compared to raised median piece in the AMP, ornamented initial part and comparatively shorter vaginal tube in L. careyensis. Ligophorus kederai n. sp. is similar to L. fenestrum, a coexisting congener, in having fenestrated ventral anchors, but differs in having longer points and narrower base. Ligophorus fenestrum, unlike L. kederai n. sp., also possesses fenestrated dorsal anchors. The principal component analysis (PCA) scatterplots indicate that the two new and eight known Ligophorus species from Malaysian mugilids can be differentiated based on the morphometries of their anchors, ventral bars and copulatory organ separately and when combined together. Numerical taxonomy (NT) analyses based on Jaccard's Index of Similarity and neighbour-joining clustering, is used to facilitate comparison of these two new species with the 50 known Ligophorus based on morphological and metric characters. The two new species are different from each other and the other 50 species in the overall shapes and sizes of hard parts, as indicated by the NT analyses.
A rapid dot immunogold filtration assay (DIGFA) was adopted for specific immunodiagnosis of human cerebral angiostrongyliasis, using purified 31-kDa glycoprotein specific to Angiostrongylus cantonensis as diagnostic antigen and protein A colloidal gold conjugate as antigen-antibody detector. A total of 59 serum samples were assayed - 11 samples from clinically diagnosed patients with detectable A. cantonensis-specific antibody in immunoblotting; 23 samples from patients with other related parasitic diseases, i.e. gnathostomiasis (n= 8), cysticercosis (n= 5), toxocariasis (n= 2), filariasis (n= 4), paragonimiasis (n= 2) and malaria (n= 2); and 25 samples from normal healthy subjects. The sensitivity and specificity of DIGFA to detect anti-A. cantonensis specific antibodies in serologically confirmed angiostrongyliasis cases, were both 100%. No positive DIGFA was observed in cases with other parasitic diseases, and the healthy control subjects. The 3-min DIGFA is as sensitive and specific as the 3-h immunoblot test in angiostrongyliasis confirmed cases that revealed a 31-kDa reactive band. The gold-based DIGFA is more rapid and easier to perform than the traditional enzyme-linked immunosorbent assay (ELISA). The test utilizing purified A. cantonensis antigen is reliable and reproducible for specific immunodiagnosis of human infection with A. cantonensis - thus can be applied as an additional routine test for clinical diagnostic support. Large-scale sero-epidemiological studies in endemic communities in north-east Thailand are under way to evaluate its usefulness under field conditions.
The lung fluke, Paragonimus westermani (Kerbert, 1878), is widely distributed in Asia, and exhibits much variation in its biological properties. Previous phylogenetic studies using DNA sequences have demonstrated that samples from north-east Asia form a tight group distinct from samples from south Asia (Philippines, Thailand, Malaysia). Among countries from the latter region, considerable molecular diversity was observed. This was investigated further using additional DNA sequences (partial mitochondrial cytochrome c oxidase subunit 1 (COI) and the second internal transcribed spacer of the nuclear ribosomal gene repeat (ITS2)) from additional samples of P. westermani. Phylogenies inferred from these again found three or four groups within P. westermani, depending on the method of analysis. Populations of P. westermani from north-east Asia use snail hosts of the family Pleuroceridae and differ in other biological properties from populations in south Asia (that use snail hosts of the family Thiaridae). It is considered that the populations we sampled can be divided into two species, one in north-east Asia and the other in south Asia.
The influence of dietary protein supplementation upon resistance to haemonchosis was examined in Dorsimal (Polled Dorset x Malin) lambs offered two levels of protein. Lambs were offered either a complete basal ruminant diet (15% crude protein (CP)) or the same diet supplemented with fish meal as a source of rumen bypass protein (19% CP). Lambs from each dietary treatment group were given either a 7-week trickle infection with Haemonchus contortus infective larvae (L3) or remained uninfected. All lambs were drenched with anthelmintic at week 8 post-infection (PI), challenged with a single dose of 5000 H. contortus L3 one week later, and killed 14 days post-challenge (PC). Lambs on the supplemented diet that were trickle infected showed a significant reduction in egg output. Supplementation and previous infection did not affect either growth rate, worm burden, worm development or haematological parameters. There was a trend for enhanced growth among supplemented non-infected lambs in comparison to lambs which received the basal ration.
Human dirofilariasis is a rare infection in Malaysia. Thus far, only two human cases have been reported viz. Dirofilaria immitis and D. (Nochtiella) repens and in both instances, adult worms were recovered from infected patients. The two cases reported in the present study, one from Melaka and the other from Penang, were diagnosed histologically. Based on the diagnostic criteria for identifying Dirofilaria in tissue sections, the parasites were identified as D. (Nochtiella) repens.
The influence of soil texture (silt, sand and laterite) and flotation solutions (saturated NaCl, sucrose, NaNO3, and ZnSO4) upon the recovery of Toxocara ova from seeded soil samples with the centrifugal flotation technique was investigated. Soil samples of different texture were artificially seeded with Toxocara spp. ova and subjected to a centrifugal flotation technique which used various flotation solutions. The results showed significant (P < 0.001) interactions between the soil types and the flotation solutions. The highest percentage of ova recovery was obtained with silty soil (34.9-100.8%) with saturated NaCl as the flotation solution (45.3-100.8%). A combination of washing of soil samples with 0.1% Tween 80, and flotation using saturated NaCl and a 30 min coverslip recovery period was used to study the prevalence of contamination of soil samples. Forty-six soil samples were collected from up to 24 public parks/playgrounds in urban areas of Petaling Jaya and suburban areas of Serdang. The prevalence of Toxocara species in the urban and suburban areas was 54.5% and 45.8% respectively.
Fifty children aged 6 to 13 years and infected with Ascaris lumbricoides were selected for the study. The number of eggs laid daily by a female Ascaris increased with increase in its length, weight and diameter. Female worms became mature and started laying eggs when they reached a length of 118 mm. Adult female worms measuring 3.7 mm or more in diameter were found to be mature. The minimum weight of a worm producing eggs was 1.1 g. On average the number of eggs produced by the female decreased with increase in the worm load.
The efficacy of ivermectin on experimental infections of P. malaysiensis in rats was determined. Ivermectin was 99.4% and 97.9% effective at a dosage of 400 meg and 800 meg respectively at seven days post-infection. The same two dosages of ivermectin when given at 14 days post infection had an efficacy of 100%. However, as an adulticide it had only 40.7% efficacy. Ivermectin may therefore be useful for the treatment of parastrongyliasis due to the larval stages of the worm which can cause significant pathology in man and animals.
The known filaricides, suramin and diethylcarbamazine citrate, were tested against subperiodic Brugia malayi infection in the leaf-monkey, Presbytis cristata. As expected, intravenous suramin at 10 mg/kg daily x 5 days or 17 mg/kg weekly x 5 weeks, did not show any microfilaricidal activity, but substantially reduced the recovery of live adult worms to 50.6% and 13.6% of controls respectively. Oral diethylcarbamazine citrate at 6 mg/kg daily x 6 or 10 days reduced final microfilarial counts to 30% of initial counts four weeks post-treatment and adult worm recovery was reduced to 4.5% and 0% of controls respectively. Although the antifilarial activity of these drugs against the infection in this non-human primate model appears to be similar to that seen in man, these results have to be confirmed using larger groups of animals.
The levels of nematode egg production in goats and the availability of infective larvae (L3) on pasture were investigated on a dairy unit in New South Wales, Australia. The output of eggs by adult goats was always above 300 epg. The profile of the graph of larval availability in herbage paralleled those for temperature and rainfall, suggesting that larval peaks occurred when the temperature and availability of moisture were optimal. The dominant genus was Trichostrongylus, followed by Haemonchus, then Ostertagia. A larger proportion of Haemonchus larvae in the cultures of faeces were collected during the summer months.
This paper reports the experimental transmission of a bird parasite into jirds. Infective larvae of Cardiofilaria nilesi obtained from laboratory colonized Coquillettidia crassipes mosquitoes which had fed on an infected chicken were inoculated subcutaneously into jirds. The number of larvae per jird varied from 10 to 228. Microfilaraemia appeared 22 to 89 days after inoculation of the infective larvae. Experiments were carried out with 24 jirds through six generations extending over a period of 22 months and 17 produced patent infections. At present 8 infected jirds are being maintained in the laboratory; their patent periods ranging from 6 to 13 months. However, the longest patent period observed was about thirteen months. The percentage of adults recovered in autopsied jirds ranged from 0 to 40 with an average of 16. The chicken showed a microfilarial periodicity with the peak microfilarial density around 2200 hours. However, in jirds there was a change in sub-periodicity. This model in the jird may be very useful for the screening of filaricides and in immunological work.
Four Presbytis cristata were treated with oral ivermectin at the same time as the subcutaneous inoculation of 100 infective larvae monthly for three months. Two animals given 0.2 mg/kg monthly and two others given 0.3 mg/kg monthly as well as three control animals became patent for microfilaraemia. However, only 1% of the infective dose was recovered as adult worms from animals in the higher drug dosage group compared to 8.2% and 6.2% in the lower dosage and control groups respectively.
Thirteen bats, Tadarida mops de Blainville, collected from the Ampang district in Kuala Lumpur, Malaysia, were found positive for the trematodes Castroia kamariae sp. nov. and Limatulum kuziai sp. nov. Two distinct but morphologically similar forms of Castroia kamariae were recovered. The morphological type is apparently determined by its location in the host intestine.
Adult worms of the rural strain of Wuchereria bancrofti in Peninsular Malaysia obtained from a successful experimental transmission in an immunosuppressed Macaca fascicularis are described for the first time. Although the worms, especially females, were slightly smaller, they were similar in morphology to those of the periodic and non-periodic W. bancrofti previously described.
Six species of strigeoid trematodes are reported from Malaysia. One new genus and 3 new species are described: Apatemon (Apatemon( jamesi sp. n (Strigeidae); cercaria Cotylurus sullivani sp. n. (Strigeidae); Neodiplostomum (Neodiplostomum) sp. (Diplostomatidae); Fibricola ramachandrani (Diplostomatidae); Pseudoscolopacitrema otteri gen. n. et sp. n. (Diplostomatidae); and cercaria Cyathocotyle malayi sp. n. (Cyathocotylidae). The life cycles of A. jamesi and C. malayi have also been investigated.
Mesocoelium malayanum sp. n. is described from the frog Rana macrodon, in Malaysia. Elongate body, broader anteriorly, measuring 1.900 (1.679-2.070) mm long by 0.404 (0.380-0.437) wide, tegument aspinose oral sucker 0.212 (0.200-0.228) by 0.202 (9.191-0.205), acetabulum 0.141 (0.132-0.150) by 0.139 (0.123-0.146), prepharynx present, oesophagus 0.115 (0.096-0.137), caeca reaching posterior 1/3 of body, anterior testis 0.097 (0.087-0.110) by 0.091 (0.087-0.100) dorsal to acetabulum, posterior testis 0.094 (0.087-0.101) by 0.092 (0.091-0.100), cirrus pouch 0.121 (0.111-0.130) by 0.047 (0.041-0.055), genital pore at left of midline of oesophagus just anterior to intestinal bifurcation, ovary 0.110 (0.091-0.127) by 0.089 (0.085-0.096) on left of body and posterior to acetabulum, vitelline glands with single follicles extending from intestinal bifurcation to ends of caeca, excretory vesicle I-shaped and eggs 0.040 (0.037-0.046) by 0.023 (0.022-0.024). Although morphologically related to M. maroccanum and M. meggitti, M. malayanum is considered to be a new species.
Stunkardia minuta sp. n. was recovered from the small intestine and rectum of 5 box-tortoises (Cuora amboinensis) in Malaysia. The average body size (L X W) is 11-42 X 2-35 mm; oral sucker 1-51 X 1.02; oral pouches 0-21 X 0.18; ventral sucker 1-67 X 1-43; oesophageal bulb 0-54 X 0-54; ant. testis 0-95 X 0-98; post. testis 0-94 X 0.94; seminal vesicle 0-82 X 0-24; ootype 0-21 X 0-41; ovary 0-41 X 0-34; and egg 121 X 83 micrometer. Although morphologically similar to S. dilymphosa, S. minuta is distinct from any other reported member of the Paramphistomidae.