Microfilariae In Circulation Research Articles

Lymphatic filariasis: Surveillance action among immigrants from endemic areas, Acre State, Brazilian Amazon

ObjectiveTo investigate the positivity of Wuchereria bancrofti (W. bancrofti) in immigrants who entered the country through Rio Branco, reducing the risk of introduction of parasites into new areas and endemic areas of the past. MethodsIt was realized a descriptive study. The AD12-ICT card test was applied on all immigrants living temporarily in the Chacara Alliance shelter, located in the metropolitan area of Rio Branco-AC, Brazil. For the positive patients, 10 mL of venous blood was collected between 11:00 pm and 1:00 am. About 4 mL of venous blood was collected to detect the presence of microfilariae in circulation in the tube using ethylene diamine tetraacetic acid and 6 mL of venous blood was collected to obtain blood serum for the Og4C3-ELISA, antibody Bm-14 and DNA-W. bancrofti tests. ResultsThe present study evaluated 415 individuals in September 2014 by circulating filarial antigen for W. bancrofti using the AD12-ICT card test. A total of 15/415 (3.61%) positive cases were found, all from Haiti. Night blood collection and serum were performed on 1/14 for confirmation the infection of W. bancrofti, which presented 34 microfilariae/mL, antigen, antibodies and PCR positives. ConclusionsThis surveillance action reveals, in a pioneering and unequivocal manner, that Brazil is an influx of immigrants carrying lymphatic filariasis and there is an urgent need to step up surveillance at the main entry point for immigrants. Active surveillance may prevent the reintroduction of lymphatic filariasis in areas under control, or prevent its introduction into other states of Brazil.

Setaria digitata microfilaraemia in Mastomys coucha: an animal model for chemotherapeutic and immunobiological studies.

Intraperitoneal implantation of adult gravid females of the bovine filarial parasite, Setaria digitata in Mastomys coucha was found to induce microfilaraemia lasting for about 125 days. The microfilariae (mf) could be detected as early as 4 days post-implantation (p.i.) and peak levels of about 30 mf in 20 microliters of blood were observed by 21 days. A significant positive correlation was found between mf density and the body weight of recipients pre-implantation. The implanted adult worms were generally viable only for less than 1 week. Implantation resulted in a significant decrease in total leucocytes and erythrocytes, induction of eosinophilia, splenomegaly and anti-erythrocyte autoantibodies. The microfilariae in circulation developed into 3rd-stage infective larvae (L3) when fed onto Aedes aegypti (refm, Liverpool strain). The mf in circulation were found to be eliminated by oral administration of diethylcarbamazine citrate, indicating the usefulness of this model for screening potential anti-microfilarial drugs. During the microfilaraemic phase, priming with tetanus toxoid (TT) resulted in significantly decreased production of anti-toxin levels indicating a state of generalized immunosuppression. Induction of antibodies to various fractionated antigenic components of adult parasites could be demonstrated by enzyme immunoassay (EIA) in M. coucha implanted with live or cold-stunned adult worms. The S. digitata-M. coucha model thus is found amenable to perform chemotherapeutic and immunobiological investigations in experimental filariasis.

Diethylcarbamazine inhibits endothelial and microfilarial prostanoid metabolism in vitro

Diethylcarbamazine (DEC) rapidly lowers the number of microfilariae in the peripheral circulation. The mechanism of action is unknown, but may involve alterations of arachidonic acid metabolism in vascular tissues. We studied the effects of DEC on arachidonic acid metabolism by bovine pulmonary arterial endothelium monolayers, human platelets and Brugia malayi microfilariae. DEC at a concentration of 2.5 microM, a level achieved in vivo, rapidly decreased prostacyclin, prostaglandin E2 and thromboxane B2 release from endothelial monolayers by 78% (P less than 0.001), 57% (P = 0.05), and 75% (P less than 0.05), respectively. High-pressure liquid chromatography of extracts of endothelial monolayers incubated with DEC showed similar inhibition of these cyclooxygenase pathway products, but exposure to the drug did not result in formation of new eicosanoids. DEC did not inhibit endothelial phospholipase A2-dependent release of arachidonate from membrane stores, whereas prostaglandin H2 synthase activity (cyclooxygenae, EC 1.14.99.1) was reduced to a degree similar to that effected by acetylsalicylic acid. Microfilarial but not platelet synthesis of cyclooxygenase products was also reduced by DEC. These data suggest that the mechanism by which DEC lowers the level of microfilariae in the circulation may in part involve its effects on host endothelial and parasite eicosanoid production.