Assessment of ivermectin therapeutic efficacy on third-stage larvae of Lagochilascaris minor in mice experimentally infected

EVALUATION OF THE THERAPEUTIC EFFICACY OF LEVAMISOLE HYDROCHLORIDE ON THIRD-STAGE LARVAE OF Lagochilascaris minor IN EXPERIMENTALLY INFECTED MICE

Lagochilascariosis, a disease caused by Lagochilascaris minor, affects the neck, sinuses, tonsils, lungs, the sacral region, dental alveoli, eyeballs and the central nervous system of humans. A cycle of autoinfection may occur in human host tissues characterized by the presence of eggs, larvae and adult worms. This peculiarity of the cycle hinders therapy, since there are no drugs that exhibit ovicidal, larvicidal and vermicidal activity. Given these facts, we studied the action of levamisole hydrochloride on third-stage larvae in the migration phase (G1) and on encysted larvae (G3) of L. minor. To this end, 87 inbred mice of the C57BL/6 strain were divided into test groups comprising 67 animals (G1-37; G3-30) and a control group (G2-10; G4-10) with 20 animals. Each animal was inoculated orally with 2,000 infective eggs of the parasite. The animals of the test groups were treated individually with a single oral dose of levamisole hydrochloride at a concentration of 0.075 mg. The drug was administered either 30 minutes prior to the parasite inoculation (G1 animals) or 120 days after the inoculation (G3 animals). The mice in the control groups were not treated with the drug. After the time required for the migration and the encysting of L. minor larvae, all the animals were euthanized and their tissues examined. The data were analyzed using the Student's unpaired t-test and the Levene test. The groups showed no statistically significant difference. Levamisole hydrochloride was ineffective on third-stage larvae of L. minor. These findings explain the massive expulsion of live adult worms, as well as the use of long treatment schemes, owing to the persistence of larvae and eggs in human parasitic lesions.

Lagochilascariasis in cats (Felis catus domesticus) in southern Brazil

Lagochilascariasis, a parasitic disease little known in Brazil, is caused by an ascarid nematode that has a peculiar life cycle, with a predilection site for the cervical region in the final hosts: humans, cats and dogs. We aimed to record the occurrence of Lagochilascaris minor in domestic cats from rural areas in the Municipality of Pelotas, Rio Grande do Sul State, Brazil, with reports of clinical signs and the treatment applied.

[Assessment of ivermectin therapeutic efficacy on fourth-stage larvae of Lagochilascaris minor in experimentally infected cats]

In order to verify the action of ivermectin against fourth-stage larvae of Lagochilascaris minor, thirty cats were divided into three groups (I, II and III). Each animal was inoculated orally with 50 third-stage larvae. The cats from groups I and II were treated with Ivermectin (200/microg/kg/single dose/sc via) on fifth day after inoculation (DAI). Treatment evaluation was performed between 30 and 40 DAI (group I) and between 180 to 190 DAI (group II) using parasite macroscopic and microscopic research at autopsy. The 10 cats from group III were untreated (control group). The authors observed 100% drug efficacy, at all observation periods, by total interruption of parasite's biological cycle in each of the treated animals. All the control group developed Lagochilascaris minor infection.