Toxocariasis Research Articles

Incidence of Toxocarosis in Synanthropic Caninds in Urban Ecosystem Chisinau

In synanthropic canids in the urban ecosystem of Chisinau 14 parasitic species (including 10 species with zoonotic impact) have been detected. They were classified by localization as follows: 6 species are ectoparasites and 8 species are endoparasites with cavitary habitat, 1 species with cavitary/ tissular habitat, 1 species with tissulary habitat and 1 species with intracellular habitat. The dynamic seasonal evaluation of imaginal toxocariasis in Canis familiaris shows approximately the same incidence level: in spring – 34,6%, in summer – 34,3%, in autumn – 35,3%, in winter – 38,5%. The appraisal by age category of imaginal toxocariasis shows a higher incidence in small dogs – 53,9%, compared to adults – 25,7%. The high incidence (35,7%) of toxocariasis in synanthropic canids in the urban ecosystem of Chisinau represents an imminent danger of human pollution infestation and pollution of the environment with the free invasive forms, a phenomenon which is out of control.

Diagnostic importance of serological methods and eosinophilia in tissue parasites.

This case-control study was carried out to investigate whether eosinophilia is a common finding in parasitic diseases and to determine the prevalence of the parasitic diseases in definitive groups. Toxocariasis and fasciolosis were investigated in patients with eosinophilia, patients with non-eosinophilia, and healthy controls. All cases were analyzed for antibodies against Toxocara canis and Fasciola hepatica by modified enzyme-linked immunosorbent assay (ELISA) employing, as antigen, excretory/secretory products of Toxocara and Fasciola (ES-ELISA). Seropositivity was determined in 39 (29.1%) and 12 (8.9%) toxocariasis and fasciolosis patients with eosinophilia respectively. The seropositivity was found in 26 (19.4%) and 5 (3.7%) toxocariasis and fasciolosis patients without eosinophilia respectively. The seropositivity was found in 13 (15.5%) and 1 (1.2%) toxocariasis and fasciolosis patients in the control group. The total seropositivity in both toxocariasis and fasciolosis in the eosinophilic group (8.5%) increased significantly compared to patients without eosinophilia (23.1%) and healthy controls (6.6%) (chi2:6.343, p < 0.05 and chi2:10.293, p < 0.01). Eosinophilia correlated with antibodies against Toxocara and E. hepatica. The results suggest that serological methods can be used for diagnosis of parasitic infections in tissue. Thus, the actual prevalence of tissue parasites can be revealed particularly in developing and emerging countries.

The epidemiology of ocular toxocariasis.

Ocular toxocariasis damages vision and may cause blindness. It is a relatively 'new' disease, the histological changes having been described in 1950 and the causative organism identified in 1956. Many aspects of the epidemiology of toxocariasis are unclear. It is generally accepted that the usual route of entry to the eye is via the blood stream. Once the eye is invaded characteristic changes are produced with comparative sparing of the anterior segment. Species differences in susceptibility can be very marked. In Mongolian gerbils 55% of infected animals exhibit ocular lesions. Humans are fortunate in that they are far less susceptible to ocular infection. While it has been established that ocular toxocariasis is caused by Toxocara canis, the role of T. cati in this condition is still unclear. It is perhaps surprising that the prevalence of such a disease in humans should remain in doubt. However, the wide variation in the few estimates of prevalence may well be a reflection of the wide variation in exposure as evidenced by the wide variation in seroprevalence. A further factor mitigating against an identification of prevalence rates is the fact that the condition is usually unilateral. Most surveys of blindness stipulate a vision of 6/60 or less in the better eye and so toxocariasis cases go unrecorded. There is a need for surveys which identify the level of vision in both eyes.

Animal models in ocular toxocariasis.

Ocular toxocariasis is a clearly defined disease. However, much remains to be learned concerning the migratory route, ocular changes, diagnosis and treatment. Studies in paratenic hosts have contributed to our understanding and will yield more information. Various experimental animals have been used, such as mice, rabbits, guinea pigs, primates, hamsters and gerbils. Of these, the last appear to be the most appropriate model due to their high susceptibility to ocular infection. Results obtained from different animal models are often not comparable due to the fact that dose and routes of inoculation are diverse. Early stages in the pathogenesis of ocular toxocariasis are manifested by haemorrhages in the anterior chamber and iris, replaced in time by accumulations of white cells. Ocular migration produces an early cell reaction, formed by an infiltration of neutrophils accompanied by vasculitis and retinal microinfarcts. Over a period of time, an increase of macrophages and the distribution of the infiltrates is observed. Later, granulomatous lesions are formed. These do not necessarily contain a larva and their appearance varies in different animal models. Local production of IgE and the presence of specific IgG have been described.

Treatment of Toxocara canis infections in mice with liposome-incorporated benzimidazole carbamates and immunomodulator glucan.

Benzimidazole carbamates (mebendazole, albendazole and fenbendazole) are the most commonly used anthelmintic drugs for the treatment of larval toxocariasis (Toxocara canis) in paratenic hosts. However, the bioavailability of these drugs for tissues is very low due to their extremely low solubility, resulting in the administration of relatively high doses over a long period. To overcome this problem, neutral, negatively or positively charged and stabilized liposome drug carriers were examined in the chronic phase of T. canis infections in mice each orally inoculated with 1000 eggs. Moreover, liposomized albendazole and fenbendazole were co-administered with liposomized immunomodulator glucan. The highest efficacy of both drugs, evaluated 4 weeks after treatment, was recorded after their subcutaneous administration (ten doses of 25 mg kg(-1)) in stabilized liposomes and intramuscular co-administration of liposomized glucan (two doses of 5 mg kg(-1)). Fenbendazole was more effective in muscles (91.5%) whereas albendazole was more effective in the brain (92.2%). Liposomes with incorporated benzimidazole carbamate anthelmintics provide sustained drug-release reservoirs and can considerably enhance drug efficacy. Moreover, despite suppression by T. canis antigens, stimulation of the immune system by the immunomodulator glucan potentiates the effects of these antiparasitic drugs.

How to stop the spread of toxocariasis

How to stop the spread of toxocariasis

Book Reviews : Toxocara and Toxocariasis by J W Lewis and R M Maizels. Published by Insdtute of Biology, 1993. 169 pp, £15.00. Paperback

Book Reviews : Toxocara and Toxocariasis by J W Lewis and R M Maizels. Published by Insdtute of Biology, 1993. 169 pp, £15.00. Paperback

Toxocariasis campaign

Toxocariasis campaign

Toxocariasis campaign

Toxocariasis campaign

Transmission of Toxocariasis

Transmission of Toxocariasis

Toxocariasis: care and complications

Toxocariasis: care and complications

Toxocariasis continued from page 280

Toxocariasis continued from page 280