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A patient with severe black fly (Simuliidae) hypersensitivity referred for evaluation of suspected immunodeficiency.

BACKGROUND: Biting flies of the Diptera order and specifically the black fly (Simuliidae family) can be rare causes of severe hypersensitivity reactions. OBJECTIVE: To describe a patient referred for evaluation of immunodeficiency whose clinical course is explained by severe Simuliidae hypersensitivity. METHODS: The patient's immune system was investigated using standard laboratory evaluations. Hypersensitivity to Simuliidae was pursued because of historical features of her presentation and was specifically examined by skin prick and intradermal testing with whole body extract. RESULTS: The patient's history was notable for recurrent and severe seasonal episodes of presumed cellulitis after black fly bites that responded poorly to intravenous antibiotics. One episode was followed by acute inflammatory demyelinating polyneuropathy (Guillain-Barré syndrome) and another by minimal change nephrotic syndrome. The results of immunologic investigations were unremarkable, but cutaneous hypersensitivity to Simuliidae was demonstrated with a 6.5-mm wheel and 35-mm flare reaction to intradermal injection of only 0.0005 microg of whole body extract. CONCLUSION: Similar to Hymenoptera, Simuliidae can rarely result in extreme hypersensitivity and should be considered in appropriate cases. This patient illustrates how severe reactions toinsect bites can be misdiagnosed.

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Evaluation of the impact of Bacillus thuringiensis serovar israelensis and Temephos, used for the control of Simulium (Chirostilbia) pertinax Kollar, 1832 (Diptera, Simuliidae) on the associated entomofauna, Paraty, state of Rio de Janeiro, Brazil.

The study was set up to evaluate the impact of two commercial larvicide formulations, Bacillus thuringiensis serovar israelensis base (Bti) at 15 ppm/1 min and temephos at 0.03 ppm of active ingredient, used to control Simulium pertinax populations, on associated non-target entomofauna occupying the same breeding sites. The experiments were carried out on the Pedra Branca and Muricana rivers, on the slopes of Serra do Mar massif, municipality of Paraty, state of Rio de Janeiro, Brazil. Bti was applied to the river Pedra Branca and temephosto theriver Muricana. On both rivers, treatment and control sections were labeled as such, each one with two observation posts: slow moving water and fast water regions respectively. Artificial substrata was used to evaluate the abundance of associated entomofauna. Attached immature stages of arthropods were removed from both of its surfaces fortnightly. Were collected, from the two rivers, 28 477 specimens of the entomofauna associated with S. pertinax. The families Hydropsychidae, Chironomidae, Bactidae, Simuliidae, Blephariceridae and Megapodagrionidae were represented. These was an impact of temephos on the entomofauna associated with S. pertinax only in Simuliidae and Chironomidae, and to Bti only in Simuliidae. However, the reduction in their numbers was not statistically significant.

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Structure and function of the cibarial armature in Simuliidae.

Cibarial armature morphology in adult female blackflies (Diptera: Simuliidae) is described using scanning electron microscopy. Three distinct types of armature are recognized, comprising those with teeth, e.g. Simulium ochraceum, S. ornatum, S. veracruzanum and S. vorax, those with spicules, e.g. Austrosimulium bancrofti, S. damnosum, S. exiguum, S. metallicum and S. neavei; and those lacking these projections, e.g. Prosimulium rufipes and S. lineatum. Whereas the armature is poorly developed in vectors of human onchocerciasis such as S. damnosum, S. exiguum, S. metallicum and S. neavei, the well-developed armature in S. ochraceum, S. veracruzanum and S. vorax does not prevent these species becoming infected with Onchocerca spp. (Nematoda: Onchocercidae). Hence the armature is not primarily a mechanism to counteract microfilaria superinfection. Since cibarial armatures are more developed in the haematophagous females than in the males of certain Families of flies, e.g. Ceratopogonidae, Culicidae, Phlebotominae and Simuliidae in the sub-order Nematocera, evidently the armature has evolved in response to the blood-feeding habit. As the suction of imbibed blood by the cibarial pump may require a valve mechanism to prevent back-flow, it is suggested that the armature is primarily for this purpose. Secondarily, the cibarial armature presents a damaging barrier against ingested microfilariae.

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A mid-arm interchange as a potential reproductive isolating mechanism in the medically important Simulium neavei group (Diptera: Simuliidae).

The Simulium neavei group is medically important as a vector of human onchocerciasis and is unique among blackflies because of the attachment to freshwater crabs during parts of the larval and pupal life cycle stages. Detailed larval salivary gland polytene chromosome maps are presented for two taxa designated S. neavei Amani form A and S. neavei Amani form B, which are probably synonymous with the previously described morphospecies, S. nyasalandicum and S. woodi, respectively. Simulium neavei Amani form B differs from S. neavei Amani form A by three paracentric inversions, a large deletion and a chromocentre, while the latter taxon differs from the former one by a mid-arm interchange. The fixed mid-arm interchange (1-tr) between two related taxa is unique among the Simuliidae. Detailed banding analysis of S. neavei Amani form B shows that, relative to S. neavei Amani form A, sections 16a, 16b, and 17c of the short arm of chromosome one (IS) have been inserted into section 69/70 of the short arm of chromosome three (IIIS). Assignment of directionality for this interchange inferred because of the near universality in the Simuliidae of a chromosome III long arm to short arm ratio of 2:1. We propose that the mid-arm interchange acted as a primary isolating mechanism because of the segregational load on F1 heterozygous interchange progeny. The magnitude of the segregational load would be dependent on the frequency of pairing and crossing-over between the transposed interstitial segment and its original counterpart in the chromosome complement. Nonpairing in the transposed region and normal random segregation would presumably lead to a 50% of gametes carrying the duplicated or deficient transposed segment, resulting in a segregation load of 50%. However, crossing-over in the paired interstitial region may greatly increase segregational load as result of multivalent formation at metaphase one (MI) and the generation of dicentric bridge(s) and acentric fragment(s) upon cell division. Such meiotic disjunction irregularities could lead to meiotic arrest, gametic loss and (or) cell restitution, and the eventual formation of polyploid (lethal) zygotes.

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[Aegla platensis Schmitt, 1942 (Decapoda: Anomura) a predator of immature stages of Simuliidae (Diptera: Culicomorpha)].

For the first time, preferential predation of larvae and pupae of Simuliidae by the crustacean, Aegla platensis Schmitt, 1942, was observed in the field and in the laboratory. Field observations and collections were done in the Carpintaria stream, Dois Irmãos, Country Rio Grande do Sul, Brazil. The possibility of using this freshwater crab in an integrated control of Simuliidae is discussed.

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[Landscape and mass-attack of Simuliidae-Diptera on man and domestic animals].

Mass-attack of Simuliidae-Diptera on man and domestic animals should not be considered only as a consequence of quality of running freshwater, but also as an effect of the actual state of the surrounding area. The territory, in fact, impacts the qualitative properties of a water body and can trigger adverse phenomena, especially so when modified by significant anthropic activities. In different locations the native settings have been replaced by deforestation, intensive farming and zootechnological activities. This paper sets forth the results of some investigations carried out further to a mass attack of Simuliidae-Diptera on man at different sites of the national territory. These results have been re-assessed taking into account the areas of interest and the modifications that they have undergone.

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Abundance and diversity of human-biting flies (Diptera: Ceratopogonidae, Culicidae, Tabanidae, Simuliidae) around a nickel-copper smelter at Monchegorsk, northwestern Russia.

In the summers of 2001 and 2002, we quantitatively sampled human-biting flies in twelve sites located 1.6 to 63 km from a large copper-nickel smelter at Monchegorsk on the Kola Peninsula, Russia. We collected 429 specimens of three species of Ceratopogonidae, 92 specimens of seven species of Culicidae, 76 specimens of seven species of Tabanidae, and 4,788 specimens of 19 species of Simuliidae. Culicoides chiropterus was for the first time reported from the Kola Peninsula. Catches of Culicidae and Simuliidae decreased near the smelter, presumably due to the combined action of toxicity of pollutants, pollution-induced forest damage, and decline in vertebrate density. An abundance of Ceratopogonidae and Tabanidae, the size of the most common black fly species, Simulium pusillum, and the diversity of all families did not change along the pollution gradient.

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A synopsis of the nematodes occurring in blackflies (Diptera: Simuliidae).

Larvae, pupae, and adult blackflies (Simuliidae) are capable of harbouring several groups of nematodes. Multiple parasitism involving nematodes of the same or different species, or various developmental stages of the same nematode may also occur. Thus, blackflies can serve as paratenic, intermediate, or definitive hosts of nematodes. The present study reviews the literature pertaining to the association between nematodes and Simuliidae and provides a key to various groups of nematodes found in blackflies. Emphasis is placed on the commoner filarial and mermithid nematodes, but several other unusual and rare roundworm parasites are also discussed.

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