The life cycle of Lagochilascaris minor was studied using material collected from human lesion and applying the experimental model: rodents (mice, hamsters), and carnivorae (cats, dogs). In mice given infective eggs, orally, hatch of the third stage larvae was noted in the gut wall, with migration to liver, lungs, skeletal musculature and subcutaneous tissue becoming, soon after, encysted. In cats infected with skinned carcasses of mice (60 to 235 days of infection) it was observed: hatch of third stage larvae from the nodules (cysts) in the stomach, migration through the oesophagus, pharynx, trachea, related tissues (rhino-oropharynx), and cervical lymphonodes developing to the mature stage in any of these sites on days 9-20 post inoculation (P.I.). There was no parasite development up to the mature stage in cats inoculated orally with infective eggs, which indicates that the life cycle of this parasite includes an obligatory intermediate host. In one of the cats (fed carcass of infected mice) necropsied on day 43 P.I., it was observed the occurence of the self-infective cycle of L. minor in the lung tissues and in the cervical region which was characterized by the finding of eggs in different stages of development, third stage larvae and mature worms. It's believed that some component of the carnivorae gastrointestinal tracts may preclude the development of third stage larvae from L. minor eggs what explains the interruption of the life cycle in animals fed infective eggs. It's also pointed out the role of the intermediate host in the first stages of the life cycle of this helminth.

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a b s t r a c tThe combination of coagulation/flocculation and ultrafiltration in the process of drinking water treatment was investigated using natural (chitosan) and chemical (aluminum sulfate) coagulants. A 0.1 m singlechannel membrane was applied at pressures of 1 bar and 2 bar, using the principle of crossflow filtration. The final produced water quality was assessed considering the efficiency of removal of color, turbidity, COD, and compounds that absorb UV at 254 nm, among other physico-chemical and microbiological parameters. The coagulation/flocculation with chitosan as coagulant (CFQ) was efficient in removing compounds that add color and turbidity and that absorb UV at 254 nm, with levels that were very similar to those obtained with the coagulation/flocculation process with aluminum sulfate as coagulant (CFS). Performance evaluation of the hybrid systems (CFS-UF and CFQ-UF) showed that the permeate quality was increased when compared with individually operated systems (UF, CFS, and CFQ). The CFQ-UF process caused higher membrane fouling (79% at 2 bar), but yielded a higher stabilized permeate flux, which was approximately twice that achieved with CFS-UF. Based on the results, one can say that chitosan has a potential application as natural coagulant in CF-UF hybrid processes for treating drinking water with relatively high turbidity.

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Cryo-microtome sections of larvae of Strongyloides stercoralis and S. ratti respectively obtained from human and rat feces cultures, were used as antigens. Fluoresceinate conjugates against human IgG were employed at the ideal titer of 10 for S. stercoralis and 100 for S. ratti. The sensitivity of the indirect immunofluorescence reaction (IIF) was 94.4% and 92.5% and the specificity 94.2% and 97.1% for the two specific larval antigens, respectively. Sera from 123 persons (54 from carriers of S. stercoralis infections and 69 from controls) were submitted to the reaction. The titers of different sera varied from 20 to 2560. There was a significant linear correlation (r = 0.85 p < or = 0.001) between the antibodies from the two species of larval antigens. We conclude that both antigens may be used in the IIF reaction for the diagnosis of human strongyloidiasis. Due to the feasibility of safe and low-cost mass production of S. ratti larvae in the laboratory with a considerable economy of conjugate, their utilization in the serum diagnosis of human strongyloidiasis is recommended.