Recent studies on the biology and ecology of adult blackflies in relation to the transmission of human onchocerciasis in Guatemala are reviewed. First, earlier studies on the transmission of the disease since its discovery by Dr. R. Robles in 1915 are outlined. Second, eleven blackfly species caught on humans are evaluated for vector status on the basis of their natural and experimental infections with third-stage larvae of Onchocerca volvulus, and Simulium ochraceum,* S. metallicum* and S. callidum are confirmed as natural vectors of the disease in Guatemala in descending order of importance, whereas S. gonzalezi, S. haematopotum, S. veracruzanum and S. horacioi are potential vectors. Third, the migration and fate of O. volvulus microfilariae ingested by female blackflies are highlighted on the basis of the findings of the cibarial armature of S. ochraceum and physiological incompatibility of S. metallicum as main barriers against microfilariae, both of which greatly decrease the number of ingested O. volvulus microfilariae developing to the third-stage larvae per female. Fourth, among many ecological factors of female blackfly populations, geographical and altitudinal distributions, habits of blood feeding, host preferences for blood feeding, preference for human body parts, parous rates, daily and seasonal fluctuations of biting activities, in particular, of parous females, gonotrophic cycle, longevity, flight range, and annual transmission potential are reviewed, and their influences on the transmission dynamics of the disease agents are considered. Fifth, effects of air temperatures on the O. volvulus–S. ochraceum complex are examined, with a special reference to the characteristic altitudinal distributions of the disease. The importance of reliable identification of both the vector blackfly species and filarial larvae found in female blackflies is emphasized to understand the transmission of the disease. [*It is now known that these two species are actually species complexes.]

Recent studies on the epidemiology and control of Guatemalan onchocerciasis, chiefly made by the Guatemala–Japan Cooperative Project on Onchocerciasis Research and Control, are reviewed. Epidemiological features of Guatemalan onchocerciasis are summarized as to characteristic altitudinal distribution of endemic areas, disease manifestation, vector taxonomy, biology and transmission dynamic of the disease. Extensive insecticide studies in the field and laboratory demonstrate that the characteristic situations of Guatemalan streams where Simulium ochraceum, the main vector of onchocerciasis, breeds require ingenious methods of larviciding. Finally, the feasibility of an area vector control is indicated by the successful control operation in the San Vicente Pacaya Pilot Area, in which a new fixed-dose larviciding method was applied.

Simulium (G.) bakalalanense, is described based on male, pupa and larvae collected in Mount Murud, Sarawak, Malaysia. S. (G.) bakalalanense sp. nov. is placed in the S. batoense species-group and is distinguished from most of known species of the group by the pupal gill with an inflated basal fenestra, shoe-shaped cocoon, and lack of grapnel-shaped hooklets on the pupal abdominal segment 9. Three known species, S. (G.) terengganuense Takaoka, Sofian-Azirun & Ya’cob from Peninsular Malaysia, S. (Simulium) alberti Takaoka from Sabah, and S. (S.) beludense Takaoka from Sabah, are newly recorded from Sarawak.

Abstract. In recent surveys of black flies in Arunachal Pradesh, North-East India, five species are newly recorded from Arunachal Pradesh: Simulium (Montisimulium) nemorivagum Datta, 1973, Simulium (Gomphostilbia) darjeelingense Datta, 1973, Simulium (Gomphostilbia) decuplum Takaoka & Davies, 1995, Simulium (Simulium) barnesi Takaoka & Suzuki, 1984 and Simulium (Simulium) pradyai Takaoka & Somboon, 2008, of which the latter three species also represent new records from India. Taxonomic reviews of two species of black flies reported from Assam show that Simulium (Gomphostilbia) unum Datta, 1975 is a junior synonym of Simulium (Gomphostilbia) darjeelingense, and the larva of Simulium (Gomphostilbia) sp. nr. varicorne Edwards is identifiable as Simulium (Gomphostilbia) parahiyangum Takaoka & Sigit, 1992.

Simulium (Gomphostilbia) taitungense sp. nov. is described on the basis of reared adult, pupal and mature larval specimens collected from Taitung, Taiwan. This new species is placed in the ceylonicum species-group within the subgenus Gomphostilbia and is distinguished from related known species by the characteristic colour markings on the ventral surface of the head capsule and on the dorsal surface of the abdomen in the larva. The male of Simulium (Gomphostilbia) tuenense Takaoka, which was originally described from a pharate pupa and a larva, is described for the first time; the association of the adult stage with the larval stage was confirmed by the comparison of the sequences of the mitochondrial 16S rRNA gene; this species is also placed in the ceylonicum species-group.

Introduction
 During the course of primary health care activities in Khammouane province of Lao PDR by non- profit organization, international support and partnership for health, an exceedingly high infant mortality rate was recognized in some villages. As thiamine deficiency was strongly suspected for the main cause of the high mortality, the household survey with an emphasis on nutritional aspect and the measurement of thiamine level in the blood of mothers as well as their breast-milk were carried out for the confirmation.
Methods
 The survey was conducted at Sibounhouane sub-district (Group 1) with the highest infant mortality and Hatkhamhieng sub-district (Group 2) with the lowest mortality. Fifty families of the two groups, each consisting of randomly selected 25 families with less than one year old infant(s) were interviewed by using prepared questionnaire. The body weight of both mother and infant was measured and blood and milk were taken from the mother.
Results
 The ethnic minorities of the group 1 consisted of Lao Lum (44%) and Lao Theung (56%), whereas only Lao Lum in the group 2. The economical indicators and the mother's educational level in the group 1 were inferior to those in the group 2. There was no significant difference in the methods of preparing staple glutinous rice, likely to flux thiamine and intake of thiaminases between the two groups. High infant mortality rate was documented in the group 1 whose clinical symptoms were mostly consistent with those of infantile beriberi. The concentration of thiamine in the blood and milk of mothers in both groups were considerably lower and significant reduction of thiamine level was observed in the group 1 than the group 2. Nevertheless, both groups of those infants tended to be inadequately fed with the foods except for breast-milk during their early infantile phase.
Conclusions
 The low concentration of thiamine in the blood and milk of mothers was strongly suggestive that infantile beriberi due to thiamine deficiency was the principal cause of the infant mortality in the study region. We hereby surmise that thiamine deficiency could be extensively prevalent in Lao PDR than the currently studied areas because of their traditional preparing methods of staple dietary rice, postpartum food taboos and intake of thiaminases. For the prevention of infant death due to severe thiamine deficiency, necessary measures including the exchange of information among the institutions concerned, adequate thiamine supplementation and nutritional counseling have to be urgently adopted.

Simulium (Simulium) chanyae sp. nov. is described based on two female adult specimens collected in Northern Thailand. This new species is assigned to the multistriatum species-group of the subgenus Simulium (Simulium), and is easily distinguished from most of the other known species of this species-group by the yellowish legs.

Simulium (Nevermannia) satakei sp. nov. is described on the basis of the pupa and mature larvae collected from the Ogasawara (Bonin) Islands in Japan. This new species, tentatively (due to lack of the adult stage) assigned to the vernum species-group of the subgenus Nevermannia, is characterized in the pupa by four gill filaments lacking transverse ridges, and in the larva by a small, M-shaped postgenal cleft, antenna without hyaline bands, and simple rectal papilla. The morphological differences among this new species and the two known species, S. (N.) uemotoi from Japan and S. (N.) karzhantacum from Uzbekistan and Turkmenistan, are noted. This is the second species of the family Simuliidae from the Islands.

Simulium (Simulium) phukaense sp. nov. is described on the basis of the observation of females and males (both sexes of adults reared from pupae) and pupae collected in Nan Province, northern Thailand. This new species is assigned to the griseifrons species-group of the subgenus Simulium (Simulium) and is easily distinguished from other known species of this species-group by the simple shoe-shaped cocoon, as well as the arrangement of the six gill filaments.

Two new species of black flies, Simulium (Nevermannia) fruticosum sp. nov. and S. (N.) chiangklangense sp. nov. are described on the basis of samples collected in northern Thailand. These new species are assigned to the feuerborni species-group of the subgenus Simulium (Nevermannia), and are easily distinguished from S. (N.) feuerborni Edwards, the only species of the same group known thus far in Thailand, by their simple cocoon without any anterodorsal projection.