The microsporidian genus Nosema is characterized by development in direct control with host cell cytoplasm, diplokaryotic nuclei throughout development and disporous sporogony. The genus Vairimorpha exhibits the same features plus an octoporous sporogony producing uninucleate spores in a sporophorous vesicle. A microsporidium from diamondback moth, Plutella xylostella, falls between Nosema and Vairimorpha in that it initiates but fails to complete the octosporous sequence in this host. The name Vairimorpha imperfecta n.sp. is proposed. Merogony is mainly by formation of buds from multinucleate meronts, the buds remaining attached in chains. Diplokaryotic spores measure 4.3 x 2.0 microns (fresh) and have 15.5 coils of the polar tube in 1 rank. The octosporous sporogony is aborted owing to irregular formation of nuclear spindles, incomplete cytoplasmic fission and bizarre deposition of electron-dense episporontal secretions. Phylogenetic analyses of the sequences of the small subunit rRNA genes of V. imperfecta and of several Nosema and Vairimorpha spp. place V. imperfecta in a clade with Nosema spp. from Lepidoptera rather than in the clade containing the more typical species of Vairimorpha. It is suggested that the ancestors of the Vairimorpha/Nosema complex of species exhibited both disporous and octosporous sporogonies, as does the type species of Vairimorpha, Vairimorpha necatrix. It would follow that true Nosema spp. have lost the ability to express an octosporous sequence and that V. imperfecta is in the process of losing it. It is proposed that the genera Nosema and Vairimorpha be placed in the same family Nosematidae Labbé 1899, rather than in separate families and orders as at present.
The Orang Asli of Malaysia continue to experience poor health. There appears to be stagnation of certain aspect of their health status. Underweight (low weight-for-age) and stunting (low height-for-age) are significant amongst Orang Asli children. Worm infestation such as Ascaris, Trichuris and hookworm continue to afflict Orang Asli communities in Malaysia. Orang Asli communities can also be afflicted by other kinds of parasites, e.g. malaria parasites, microsporida parasites and Cryptosporidium parasites. Thus, primary care doctors who treat Orang Asli patients should be on the lookout for malnutrition and its effects (including anaemia, iodine deficiency, Vitamin A deficiency) as well as worm and parasite infestations. Such patients may need to undergo de-worming at regular intervals because of the tendency to get re-infected. Primary care doctors also need to be aware of possible interactions between infestations and nutritional deficiencies.