Morphological and molecular characteristics of Malayfilaria sofiani Uni, Mat Udin & Takaoka n. g., n. sp. (Nematoda: Filarioidea) from the common treeshrew Tupaia glis Diard & Duvaucel (Mammalia: Scandentia) in Peninsular Malaysia.

BACKGROUND: The filarial nematodes Wuchereria bancrofti (Cobbold, 1877), Brugia malayi (Brug, 1927) and B. timori Partono, Purnomo, Dennis, Atmosoedjono, Oemijati & Cross, 1977 cause lymphatic diseases in humans in the tropics, while B. pahangi (Buckley & Edeson, 1956) infects carnivores and causes zoonotic diseases in humans in Malaysia. Wuchereria bancrofti, W. kalimantani Palmieri, Pulnomo, Dennis & Marwoto, 1980 and six out of ten Brugia spp. have been described from Australia, Southeast Asia, Sri Lanka and India. However, the origin and evolution of the species in the Wuchereria-Brugia clade remain unclear. While investigating the diversity of filarial parasites in Malaysia, we discovered an undescribed species in the common treeshrew Tupaia glis Diard & Duvaucel (Mammalia: Scandentia). METHODS: We examined 81 common treeshrews from 14 areas in nine states and the Federal Territory of Peninsular Malaysia for filarial parasites. Once any filariae that were found had been isolated, we examined their morphological characteristics and determined the partial sequences of their mitochondrial cytochrome c oxidase subunit 1 (cox1) and 12S rRNA genes. Polymerase chain reaction (PCR) products of the internal transcribed spacer 1 (ITS1) region were then cloned into the pGEM-T vector, and the recombinant plasmids were used as templates for sequencing. RESULTS: Malayfilaria sofiani Uni, Mat Udin & Takaoka, n. g., n. sp. is described based on the morphological characteristics of adults and microfilariae found in common treeshrews from Jeram Pasu, Kelantan, Malaysia. The Kimura 2-parameter distance between the cox1 gene sequences of the new species and W. bancrofti was 11.8%. Based on the three gene sequences, the new species forms a monophyletic clade with W. bancrofti and Brugia spp. The adult parasites were found in tissues surrounding the lymph nodes of the neck of common treeshrews. CONCLUSIONS: The newly described species appears most closely related to Wuchereria spp. and Brugia spp., but differs from these in several morphological characteristics. Molecular analyses based on the cox1 and 12S rRNA genes and the ITS1 region indicated that this species differs from both W. bancrofti and Brugia spp. at the genus level. We thus propose a new genus, Malayfilaria, along with the new species M. sofiani.

Filariasis in Tak Province, northwest Thailand: the presence of subperiodic variant Wuchereria bancrofti.

The microfilariae found in carriers at Tak Province, Northwestern Thailand were morphologically and morphometrically studied. It was found that the parasites conformed to that of W. bancrofti microfilaria. The microfilarial periodicity as determined from four carriers was found to be nocturnally (early evening) subperiodic type showing a distinct peak at 1800 hours.

[Morphology of adult and sub-adult Wuchereria bancrofti. Differential characteristics among the strains]. / Morphologie de Wuchereria bancrofti adulte et sub-adulte. Recherche de caractères différentiels entre les souches.

The description of the fourth stage larva of W. bancrofti provides an indication of the direction of morphological evolution in the genus showing in particular that W. kalimantani is more highly evolved than W. bancrofti and constitutes a "capture" by Presbytis of the species parasitic in man. No morphological character of adult W. bancrofti distinguishes the geographic origin of the different collections studied. By contrast, the morphological characters of the microfilariae and their biological features are significantly different, but are not inter-correlated. It therefore appears that in the genus Wuchereria, as in the other viviparous filarioids, the phenomenon of speciation is evident first of all in the morphology of the microfilaria, the stage most susceptible to selection pressures.

Filarid parasites of South Kalimantan (Borneo) Indonesia. Wuchereria kalimantani sp. n. (Nematoda: Filarioidea) from the silvered leaf monkey, Presbytis cristatus Eschscholtz 1921.

On the basis of morphological characteristics of adult and microfilarial stages, Wuchereria kalimantani sp. n. (Nematoda: Filarioidea) is described. The parasites were recovered from the inguinal lymph nodes and testes of silvered leaf monkeys (Presbytis cristatus) from a rubber estate, Banjar Regency, South Kalimantan (Borneo), Indonesia. Adult males are characterized by having more than 24 caudal papillae, a left spicule with a simple lamina, four pairs of sessile caudal papillae, a blunt tail, a mean overall length of 41 mm, and sheathed microfilariae with a nude tail tip; accordingly, the parasite is placed in the genus Wuchereria. This is the second species of Wuchereria described on the basis of both adult and embryonic forms, and is the first such species that has been found to infect primates naturally.

A description of adult Wuchereria bancrofti (rural strain) from an experimental infection in the long-tailed macaque, Macaca fascicularis (sny. M. irus).

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.

Ultrastructure of the anterior alimentary tract of infective-stage Wuchereria bancrofti (Nematoda: Filarioidea).

The anterior alimentary tract of infective-stage Wuchereria bancrofti is divided into the following segments: stoma or buccal capsule, muscular esophagus, glandular esophagus, esophageal-intestinal valve, and intestine. Invaginated external cuticle lines only the anterior stoma. External cuticle and esophageal lining are not continuous and are ultrastructurally distinct; the latter is compared morphologically to the amorphous component of elastin. The glandular esophagus is a composite structure of a stellate contractile epithelial core, surrounded by a sleeve of secretory epithelium. The glandular cytoplasm shows evidence of formation and release of dense secretory granules. At least 2 nerve cell bodies lie within the esophagus approximately 15 micrometer anterior to the esophageal-intestinal valve and their associated processes pass forward and backward through the contractile epithelium. Materials interpreted as ingested flight muscle mitochondria of the mosquito vector appear in various stages of degeneration within the intestinal lumen. It is suggested that, although simple by comparison to some other nematodes, the anterior alimentary tract of infective-stage W. bancrofti functions in the ingestion and breakdown of nutrient materials. The ultrastructure of the excretory cell likewise suggests a functional capability.

The differentiation of brugia malayi, B. pahangi, B. tupaiae and Wuchereria bancrofti.

During studies on filariasis in Thailand, attempts were made to differentiate Wuchereria bancrofti and Brugia spp. by morphological characteristics, as well as by vector species.