A new type of advanced third-stage larvae of the genus Gnathostoma in freshwater eels, Fluta alba, from Nakhon Nayok, central Thailand.

Five advanced third-stage larvae of a newly identified type of genus Gnathostoma were collected from freshwater eels, Fluta alba, which were purchased at a market in Nakhon Nayok, central Thailand. The most remarkable characteristic of the newly identified larvae was the larger body size compared with any other larva of Gnathostoma spp. They were also distinguishable from other species by the shape of their hooklets, which branched in a complex manner at the base: this had not been previously observed in any other larval Gnathostoma. The newly described larvae had an average number of 44.5, 45.0, 49.0 and 55.1 hooklets on the head-bulb from the first to the fourth rows, respectively, which were comparable to those of larval G. spinigerum. However, the average number of nuclei in each intestinal cell was 2.21 and fewer than those of the larvae of G. spinigerum. These results suggest that the new type of larvae belong to either G. vietnamicum, G. malaysiae, or constitute a new species of the genus Gnathostoma.

Gnathostomiasis in Thailand: a survey on intermediate hosts of Gnathostoma spp. with special reference to a new type of larvae found in Fluta alba.

To clarify current status of gnathostomiasis in Thailand, a survey on intermediate hosts has been carried out at various localities since 1987. It was found that Fluta alba (Fresh water eel) as well as Channa striata (snake-headed fish) might be important in playing a role of transmitting the infection either among humans or reservoir animals. During the three years from 1987 to 1989, larvae of Gnathostoma spinigerum were found in 80-100% of F. alba obtained from markets in Nakhon Nayok, with a maximum recovery of 2,582 larvae per eel. Among larvae found in these eels, five were peculiar in possessing four rows of hooklets with complicated branches at the base. Epithelial cells of the intestine of these larvae contained 1-2 nuclei. These observations indicate that the larvae are different from those of reported species of Gnathostoma from Thailand including G. spinigerum, suggesting a possibility of the advanced third-stage larvae of G. malaysiae.

Effect of single-dose albendazole and single-dose mebendazole on Necator americanus.

One hundred two children (43 males and 59 females) aged 6 to 14 years with positive stool examination by Kato-Katz and/or Harada-Mori culture techniques for N. americanus, were randomly divided into two groups. Group I with 48 children were treated with a single dose albendazole, 400 mg. Group II, 54 children, received a single dose mebendazole, 600 mg. After treatment, repeated stool examination was performed on Day 14, Day 21 and Day 28. The children were considered cured when stool examination was negative on all three occasions by both methods. The cure rate was 64% in Group I and 11% in Group II. The difference was statistically significant (p less than 0.05). The eggs reduction rate was 98% in Group I and 95% in Group II. Mild and transient side effects such as nausea, dizziness and headache were observed in both groups. Albendazole, 400 mg, as a single dose treatment was shown to be superior to mebendazole, 600 mg, single dose for the mass treatment of hookworm infection, especially that of Necator americanus, in an endemic area.

Circumoval and larval microprecipitation reactions in experimental and human gnathostomiasis.

Mice, rats and cats were infected either orally or percutaneously with a number of early or advanced third-stage larvae (EL3 or AL3, respectively) of G. spinigerum. Sera obtained from these infected animals and 10 human gnathostomiasis cases were tested against various developmental stages of the parasite which were prepared and used while being alive (fresh) or dead (air-dried) for the circumoval and larval microprecipitation (COP and LMP) reactions. No precipitin reactions were observed in all sera tested against unembryonated eggs, embryonated eggs and first stage larvae neither air-dried nor fresh preparations. Sera were merely reactive giving various degrees of membranous or filamentous precipitates against the air-dried preparation of AL3.

Transmammary transmission of Necator americanus larva in the human host.

The prevalence of Necator americanus in the 128 nursing mothers at Saraburi hospital was 61%. The examination of milk from these mothers revealed the presence of N. americanus in one case. The finding suggested that milk could be a potential source of hookworm infection in man.

Experimental cross-breeding of Ancylostoma tubaeforme (Zeder, 1800) and Ancylostoma caninum (Ercolani, 1859).

In experimental crosses between A. tubaeform and A caninum the worms failed to produce progeny in dual-strain combinations. Even though these two strains did not fail to copulate. Egg production was observed only in identical single-strain combinations. This supports the assumption that the two species are genetically separate and valid.

Prevalence and zoonotic potential of Ancylostoma ceylanicum in cats in Thailand.

Ancylostoma ceylanicum and Ancylostoma caninum were found in cats from Prachin Buri, Thailand, with infection rates of 92% and 23%, respectively. In this survey, 75% of cats were infected with A. ceylanicum alone, the rest had mixed infections of A. ceylanicum and A. caninum. The worm burden range in 26 cats for A. ceylanicum and A. caninum were 1 to 83 and 1 to 10, respectively. For A. ceylanicum, both males and females were found in the gut from the first part of duodenum to rectum. In the case of A. caninum the distribution was not constant. The sex ratio between male and female A. ceylanicum was 1:1.4. The egg count for A. ceylanicum was in the range 31-150 per gram of faeces (mean 70). The zoonotic potential of these parasites was discussed.

Light microscopy and scanning electron microscopy of Bathmostomum sangeri Cobbold, 1879, of elephants.

Bathmostomum sangeri is an intestinal parasite of the elephant. Males measured 12.15-14.25 mm in length; females measured 14.98-17.68 mm in length. Buccal capsule is well-developed and funnel-shaped. There is a raised and transverse fissure ridge around the oral margin. The internal wall of the buccal capsule is raised into a series of circular ridges or lamellae. Teeth or cutting plates could not be seen. Spicules are stout, wing-like structures. The telamon is pear-shaped, but a gibernaculum is not present. There are two pairs of papillae on the either side of the cloacal opening. The female tail is gradually tepering.

Morphology of Ancylostoma buckleyi Le Roux and Biocca, 1957 in dogs from Cairns, North Queensland, Australia.

Ancylostoma buckleyi was found in dogs in Cairns, North Queensland, Australia. Worms were small, whitish, males 10.25-10.89 mm in length; females 12.65-14.96 mm in length. The buccal capsule was funnel shaped. There were three pairs of ventral teeth and two pairs of dorso-lateral teeth. Spicules were simple and equal, 0.71-0.73 mm in length. Gubernaculum was shaped like a cricket bat, the widest part in the posterior half. The bursa was well developed, the ratio between posterolateral-mediolateral to mediolateral-externolateral was 1:1. The inner branches of the dorsal rays were partially fused. Tail of the femaleworm was 0.22-0.23 mm in length and conical.

Hypodontus macropi, Mönnig, 1929 from a Bennetts' wallaby Macropus rufogrisea.

Hypodontus macropi was found in Macropus rufogrisea. Males measured 12.73--13.93 mm in length; one female was 19.07 mm in length. The buccal capsule was funnel-shaped. The mouth opening was directed antero-ventrally. There was a pair of large cutting plates on the dorsal margin of the buccal capsule. The brusal rays were well-developed. Spicules were equal and each bore a cuticular wing. A gubernaculum and a telamon were present. The vulva was situated near the anus. The female tail, 0.163 mm in length, was suddenly tapering.

Ancylostoma malayanum, Alessandrini, 1905 in Thailand.

Ancylostoma malayanum was recorded from a Malayan Sunbear, Helarctos malayanus, in Nakorn Sri Thammarat Province, Southern Thailand. Comparison of the body measurements recorded by various authors were presented. The morphological features were described and illustrated, including the anogenital papillae.

Scanning electron microscopy of hookworms. 2. Adult of arthrostoma longspiculum (Maplestone, 1931).

The surface structures of adult Arthrostoma longespiculum were studied with the aid of the scanning electron microscope. In the mouth opening, a pair of ventral cutting plates was present; each was semilunar, thick and rounded at the inner edge. Cervical papillae were paired, small and sharp. The vulvar papilla was a single, round, wart-like projection adjacent to the vulva.

Comparative morphology of genital cones of genus Ancylostoma Dubini, 1843.

Male worms of Ancylostoma braziliense, A. ceylanicum, A. kusimaense, A. malayanum, A. duodenale, A. caninum, A. tubaeforme, Agriostomum vryburgi and Cyclodontostomum purvisi have the external appendages beside the anogenital aperture. These anogenital structures are morphologically similar and are assumed to be homologous among the species with three pairs of teeth or more. In hookworms with two pairs of teeth, the anogenital structures are complex. Anogenital features can be used as a taxonomic character in separating the species.