Ann Trop Med Parasitol. 2010 Jan;104(1):3-23.
Human toxocariasis: diagnosis, worldwide seroprevalences and clinical expression of the systemic and ocular forms.
Laboratory of Seroepidemiology and Immunobiology, Institute of Tropical Medicine of São Paulo, Avenida Dr Enéas de Carvalho Aguiar 470, 05403-000, São Paulo, SP, Brazil. firstname.lastname@example.org
Although human toxocariasis ranks among the most common zoonotic infections worldwide, it remains relatively unknown to the public. The causal agents are the nematode parasites Toxocara canis and T. cati, whose definitive hosts are dogs and cats, respectively. When embryonated eggs are accidentally ingested by humans, larvae hatch in the small intestine, penetrate the intestinal wall and migrate, via the bloodstream, to the liver, lungs, muscles, eye and central nervous system. Although most human infections are asymptomatic, two well-defined clinical syndromes are classically recognised: visceral larva migrans (a systemic disease caused by larval migration through major organs) and ocular larva migrans (a disease limited to the eyes and optic nerves). Two less-severe syndromes have recently been described, one mainly in children (covert toxocariasis) and the other mainly in adults (common toxocariasis). Here, the current laboratory diagnosis, epidemiology and main clinical features of both the systemic and ocular forms of human toxocariasis are reviewed. New developments in serological diagnosis are described, the available seroprevalence data are analysed, and the results of relevant clinical studies that have been published over the last decade are explored, to provide an updated overview of this neglected but highly prevalent human infection.
PMID: 20149289 [PubMed - indexed for MEDLINE]
J Allergy Asthma Immunol. 2009 Sep;8(3):161-4.
Toxocariasis resulting in seeming allergy.
Allergy Service, Istituti Clinici di Perfezionamento, Milano, Milan, Italy. email@example.com
Toxocara canis is an intestinal nematode affecting dogs and cats that causes human infestations by ingestion of embryonated eggs excreted in dogs' faeces. Humans are transport hosts, in whom the larvae do not develop to adult worms, but may migrate to various tissues and organs, and survive for several years, giving rise to several clinical symptoms, which include allergy-like presentations. We report three cases presenting as dermatitis, rhinitis, asthma, and conjunctivitis which were diagnosed and unsuccessfully treated as allergy. The correct diagnosis was established after detecting anti-Toxocara antibodies by Western blotting. All clinical symptoms showed improvement after starting treatment with mebendazole and subsequent courses of the antiparasitic drug resulted in full recovery. This suggests the possible role of Toxocara canis in inducing chronic symptoms of allergic type. This is particularly important for asthma, where it has been demonstrated that Toxocara canis infection causes allergic inflammation in the lungs associated with bronchial hyperreactivity. On the other hand, in our patients with asthma and with dermatitis the positive results from allergy tests were a confounding factor in delaying the correct diagnosis, which was finally obtained by the detection of antibodies to Toxocara canis.
PMID: 20124608 [PubMed - indexed for MEDLINE]
J Egypt Soc Parasitol. 2009 Dec;39(3):731-44.
Seroprevalence of human toxocariasis (visceral larva migrans).
Department of Parasitology, Faculty of Medicine, Mansoura University, Egypt.
A total of 455 patients who fulfilled the inclusion criteria were included in the study. The enrolled patients were subjected to a questionnaire (including sociodemographic and other risk factors) and thorough clinical examination was done for the patients. Sera were collected from patients and tested for anti-Toxocara IgG antibodies using ELISA. The overall anti- Toxocara seropositive was (7.7%). It was significantly higher than among the randomly selected 30 healthy controls. There were no significant differences between the seropositive and seronegative patients regarding age, sex, educational level and monthly family income of the patient. However, rural residence, poor house, pet's ownership and frequent contact with soil were found to be significant. Patients who had confirmed bronchial asthma were more than 2 times at higher risk of developing toxocariasis (OR, 2.33; 95% CI, 1.09-4.98) than those with other clinical diagnosis (PUO, hepatomegaly or heptosplenomegaly, lymphadenopathy, neurological disorders, gastrointestinal troubles and dermatitis). Patients with eosinophilia were at 149 times greater risk of being Toxocara seropositive compared to those without eosinophilia (OR, 148.7; 95% CI: 53.5-413.3). Multivariate regression analysis showed eosinophilia and contact with soil were the most important predictors of toxocariasis. OD of anti-Toxocara antibodies (ELISA) was significantly positive with eosinophilia level.
PMID: 20120741 [PubMed - indexed for MEDLINE]
J Korean Med Sci. 2009 Dec;24(6):1024-30. Epub 2009 Nov 7.
Toxocariasis might be an important cause of atopic myelitis in Korea.
Department of Medicine, Center for Health Promotion, Samsung Medical Center, Seoul, Korea.
Atopic myelitis is defined as myelitis with atopic diasthesis but the cause is still unknown. Toxocariasis is one of the common causes of hyperIgEaemia that may lead to neurologic manifestations. The purpose of this study was to evaluate the sero-prevalence of Toxocara specific IgG Ab among the atopic myelitis patients. We evaluated the medical records of 37 patients with atopic myelitis whose conditions were diagnosed between March 2001 and August 2007. Among them, the 33 sera were analyzed for specific serum IgG Ab to Toxocara excretory-secretory antigens (TES). All of 37 patients had hyperIgEaemia. Specific IgE to D. pteronyssinus and D. farinae was detected in 22 (64.7%) and 34 (100%) patients, respectively, of the 34 patients. Thirty-one of 33 patients (93.9%) were found to be positive by TES IgG enzyme-linked immunosorbent assay (ELISA). Based on the image findings of eosinophilic infiltrations in the lung and liver, 8 patients had positive results. These results inferred that the prevalence of toxocariasis was high in patients with atopic myelitis. Our results suggest that toxocariasis might be an important cause of atopic myelitis and Toxocara ELISA is essential for evaluating the causes of atopic myelitis.