Toxocara canis larvae are one of the most overlooked agents of nervous system infection in paratenic hosts. Previous studies in mouse models have shown that infection with various (mainly high) numbers of larvae leads to neurobehavioral disturbances and pathological changes. Our study investigated whether the infection with low and moderate numbers of larvae could affect the physical condition, motor skills, and pathogenesis in the brains of experimentally infected mice.Two groups of BALB/c mice were orally infected with 10 and 100 T. canis larvae per animal and examined regularly until the 97th week after infection. General appearance, specific antibody responses, and motor/balance skills were assessed. The number and viability of larvae in the liver, spleen, lungs, and brain were assessed by quantitative compressed biopsy technique, while the pathological changes of the brain infection were studied histologically.As a result, changes were observed in overall appearance, activity, as well as motor and balance ability. The infections were associated with an increased IgG antibody response to the specific anti-T. canis excretory/secretory antigen and tissue damage in the brain characterized by necrosis, cell infiltrations, including foamy cells, and hemorrhages.The study demonstrated the effects of low and moderate T. canis infection in a paratenic host during the chronic phase of infection, which lasted up to 97 weeks for the first time.

• Keywords
• Toxocara canis, Mice, Moderate to low inoculum, Neurobehavioral disorders, Pathological changes,
• MeSH
• Behavior, Animal MeSH
• Immunoglobulin G blood   MeSH
• Liver parasitology   pathology   MeSH
• Larva * MeSH
• Disease Models, Animal MeSH
• Brain * parasitology   pathology   MeSH
• Mice, Inbred BALB C * MeSH
• Mice MeSH
• Antibodies, Helminth blood   MeSH
• Toxocara canis * MeSH
• Toxocariasis * parasitology   pathology   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Mice MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Immunoglobulin G MeSH
• Antibodies, Helminth MeSH

Using a small animal imaging system, migratory activity of Toxocara canis larvae stained by carboxyfluorescein succinimidyl ester (CFSE) was observed post primary infection (PPI) and post reinfection (PR) of BALB/c mice. Each infection was performed with 1,000 larvae per mouse. Primary infections were performed with labeled larvae, while for challenge infections the reinfecting larvae were stained by CFSE. The worm burden in mouse organs was determined during a period from 6 h to 21 days and 4 months PPI and PR. In comparison with primary infections that led to the first larvae appearance in the brain after 60 h, greatly accelerated migration of the parasites administered 3 weeks PPI to the CNS and eyes of challenged mice was noted-in both organs the larvae appeared 6 h PR. In all challenged mice, reinfecting larvae prevailed in the resident parasite population. Preliminary experiments with Toxocara cati larvae also revealed early brain involvement in primarily infected mice. Staining of T. canis larvae by CFSE had no effect on the development of a humoral antibody response against T. canis excretory-secretory antigens. In ELISA, elevated levels of specific IgG and IgG1 were noted on day 14 PPI and the levels of antibodies increased till the end of experiment. Reinfection induced an increase in the levels of both antibodies. In terms of optical density, IgG1 antibodies gave higher values in all sera examined. In ELISA for IgG antibodies, an increase in the avidity index of around 50% was detected 1 month PPI; higher-avidity antibodies were also detected in sera of reinfected animals.

• MeSH
• Staining and Labeling MeSH
• Time Factors MeSH
• Enzyme-Linked Immunosorbent Assay MeSH
• Central Nervous System Helminthiasis pathology   MeSH
• Immunoglobulin G blood   MeSH
• Larva pathogenicity   MeSH
• Brain parasitology   MeSH
• Mice, Inbred BALB C MeSH
• Mice MeSH
• Eye parasitology   MeSH
• Eye Diseases parasitology   pathology   MeSH
• Parasite Load MeSH
• Antibodies, Helminth blood   MeSH
• Toxocara canis pathogenicity   MeSH
• Toxocariasis parasitology   pathology   MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Immunoglobulin G MeSH
• Antibodies, Helminth MeSH