Find information on thousands of medical conditions and prescription drugs.

Toxocariasis

Toxocariasis is a parasitic infection with the dog or cat roundworm, Toxocara canis or Toxocara cati, respectively. Ingestion of these worms causes the condition, visceral larval migrans. more...

Home

Tarsal tunnel syndrome

Tay syndrome ichthyosis

TEN

Tetanus

Thoracic outlet syndrome

Thymoma

Tick-borne encephalitis

Touraine-Solente-Golé...

Tracheoesophageal fistula

Trachoma

Transient...

Transient Global Amnesia

Transposition of great...

Transverse myelitis

Traumatophobia

Treacher Collins syndrome

Tremor hereditary essential

Trisomy

Typhoid

Typhus

Tyrosinemia

Medicines

Epidemiology

Toxocariasis is a worldwide infection. Epidemiologic surveys show a 2-5% positive rate in healthy adults from urban Western countries and 14.2-37% in rural areas. In tropical countries, surveys show a positive rate of 63.2% in Bali, 86% in Saint Lucia, and 92.8% in Réunion. Toxocariasis is most commonly a disease of children, typically children aged 2-7 years.

Pathophysiology

Adult worms of the Toxocara species live in the small intestine of dogs and cats. They range from 4-12 cm in length. Almost all puppies are infected at or soon after birth. During the summer, Toxocara eggs are shed and become infective. They survive for years in the environment, and humans typically ingest the eggs by oral contact with contaminated hands. Once introduced into the human intestine, the eggs hatch, releasing the larvae. The larval form is less than 0.5 mm in length and 0.02 mm wide. The larvae penetrate the bowel wall and migrate through vessels to the muscles, liver, and lung and sometimes to the eye and brain as well.

Disease severity depends not only on the number of larvae ingested but also on the degree of allergic reaction. The inflammatory reaction causes epithelial cells to surround each larva, and, subsequently, a dense fibrous capsule invests each granuloma.

Features

Weakness
Pruritus
Rash
Difficulty breathing
Abdominal pain
Eosinophilia
Increased total serum immunoglobulin E (IgE) level
Elevated antibody titers to T canis

Diagnosis

In suspected cases, diagnosis is confirmed by an increase in the anti-Toxocara excretory-secretory antigen IgE level

Treatment

Mebendazole or thiobendazole are the treatments of choice.

Prognosis

Toxocariasis is almost always a benign, asymptomatic, and self-limiting disease, although brain involvement can cause brain damage, meningitis, encephalitis, or epilepsy. Ocular involvement may cause loss of visual acuity or unilateral blindness. Pulmonary and hepatic forms can cause protracted symptoms if the patient does not receive treatment.

Prevention

The eggs of Toxocara species are widespread in parks, playgrounds, yards, and in homes and apartments where the occupants have dogs or cats. Elimination of eggs from the environment is not possible; therefore, prevention depends on proper hygiene, including handwashing after contact with pets. Public policies that have attempted to eradicate Toxocara infection in dogs and cats have had limited success.

Read more at Wikipedia.org

• [List your site here Free!]

Human toxocariasis: Incidence among residents in the outskirts of Campinas, State of Sao Paulo, Brazil
From Revista do Instituto de Medicina Tropical de Sao Paulo, 9/1/03 by Filho, Francisco Anaruma

SUMMARY

With the aim of estimating the incidence of infection by Toxocara among residents in the outskirts of Campinas (State of Sao Paulo, Brazil) two serological surveys, using ELISA anti-Toxocara tests, were performed in January 1999 and January 2000, involving, respectively, 138 and 115 individuals, 75 of which examined in both occasions. Among this group 67 individuals did not show the presence of anti-Toxocam antibodies in 1999, and 12 presented seroconversion in the second survey, revealing an annual incidence rate of 17.9%.

KEYWORDS: Human toxocariasis; Toxocara canis; Incidence; ELISA; Campinas, SP, Brazil.

Visceral larva migrans is a zoonosis determined by the prolonged migration of some nematode larvae through human tissues. Toxocara canis and T. cati are common ascarids of dogs and cats and considered the principal aetiological agents of this syndrome. Humans are infected after ingestion of either embrionated eggs of those ascarids or tissues of infected paratenic hosts10,13.

Human infection by Toxocara has a worldwide distribution, with variable frequencies, depending on local factors such as close contact with soil contaminated mainly by dog faeces and low income level of the community5,9. The rate of infection and occurrence of symptoms are more frequent in children12,13, principally in rural areas7,10; however, albeit less frequently, adults have also been involved. The most common signs and symptoms include fever, respiratory complaints and hepatomegaly6,10.

Several studies have investigated human infection by Toxocara in Brazil, usually finding high frequencies1,2,4,11,14. However, in this Country, as in many other regions, data on the incidence rate are not available, since almost all field investigations had been designed as transversal studies, considering only one moment of the infection's natural history.

With the aim of estimating the rate of infection by Toxocara among the residents of three boroughs located in the outskirts of the city of Campinas (State of Sao Paulo, Brazil) two serological surveys were performed: the first in January 1999 and other in January 2000, involving respectively 138 and 115 randomly selected volunteers. Among these, evaluating 75 individuals who were examined in both occasions, was possible to calculate the annual incidence rate.

In each survey the sera were tested for the presence of anti-Toxocara IgG antibodies through enzyme-linked immunosorbent assay (E.L.I.S.A.), using an excretion-secretion antigen obtained from T. canis larvae maintained in Eagle's medium at laboratory8. To avoid cross-reactions with Ascaris antigens, a soil-transmitted roundworm frequent in the studied region and to improve test specificity, each serum was previously submitted to absorption with Ascaris siiwn extracts4. Serological examinations were carried out at the Serology Section of the Central Laboratory of the Adolfo Lutz Institute employing technique standardized in that laboratory3. The ELISA cut-off had been determined every day using human positive and negative sera.

The objective of the study was clearly explained to all those involved and their informed consent was solicited before collecting blood samples.

The results of the first survey were published elsewhere2 and showed a prevalence rate of 23.9% for Toxocara infection. In the second survey, carried out one year later, 24/115 (20.9%) individuals examined showed anu-Toxocara antibodies in their blood samples. Considering the 75 residents examined in both surveys, 67 had negative results in 1999 and 12 presented seroconversion in the second survey, revealing an annual incidence rate of 17.9% for Toxocara infection in the studied area.

Among the 12 individuals presenting seroconversion to anu-Toxocara antibodies, eight (66.7%) were less than 10 years old, pointing out the role of visceral larva migrans as a pediatric disease10,13 but also calling attention to the occurrence, although not so common, of Toxocara infections in adults.

REFERENCES

1. ALDERETE, J.M.S.; JACOB, C.M.A.; PASTORINO, A.C. et al. - Prevalence of Toxocara infection in schoolchildren from the Butanta region, Sao Paulo, Brazil. Mem. Inst. Oswaldo Cruz, 98: 593-597, 2003.

2. ANARUMA FILHO, F.; CHIEFFI, P.P.; CORREA, C.R.S. et al. - Human toxocariasis: a seroepidemiological survey in the municipality of Campinas (SP), Brazil. Rev. Inst. Med. trop. S. Paulo, 44: 303-307, 2002.

3. CAMARGO, E.D.; NAKAMURA, P.M.; VAZ, A.J. et al. - Standardization of DOT-ELISA for the serological diagnosis of toxocariasis and comparison of the assay with ELISA. Rev. Inst. Med. trop. S.Paulo, 34: 55-60, 1992.

4. CHIEFFI, P.P.; UEDA, M.; CAMARGO, E.D. et al. - Visceral larva migrans: a seroepidemiological survey in five municipalities of Sao Paulo State, Brazil. Rev. Inst. Med. trop. S. Paulo, 32: 204-210, 1990.

5. CILLA, G.; PEREZ TRALLERO, E.; GUTIERREZ, C.; PART, C. & GOMARIZ, M. -Seroprevalence of Taxocara infection in middle-class and disadvantaged children in Northern Spain (Gipuzkoa, Basque Country). Europ. J. Epidem., 12: 541-543, 1996.

6. EHRHARD, T. & KERNBAUM, S. - Toxocara canis et toxocarose humaine. Bull. Inst. Pasteur, 77: 225-287, 1979.

7. EMBIL, J.A.; TANNER, C.E.; PEREIRA, L.H. et al. - Seroepidemiologic survey of Toxocara canis infection in urban and rural children. Publ. Hlth. (Lond.), 102: 129-133, 1988.

8. GLICKMAN, L.; SCHANTZ, P.; DOMBROSKE, R. & CYPESS, R. - Evaluation of serodiagnostic tests for visceral larva migrans. Amen J. trop. Med. Hyg-, 27: 492-498, 1978.

9. LYNCH, N.R.; EDDY, K.; HODGEN, A.N.; LOPEZ, R.I. & TURNER, K.J. -Seroprevalence of Toxocara canis infection in tropical Venezuela. Trans, roy. Soc. trop. Med. Hyg., 82: 275-281, 1988.

10. MAGNAVAL, J.F.; GLICKMAN, E.T.; DORCHIES, P. & MORASSIN, B. - Highlights of human toxocariasis. Korean J. Parasit., 39: 1-11, 2001.

11. MOREIRA-SILVA, S.F.; LEAO, M.E.; MENDONCA, H.F. & PEREIRA, F.E. -Prevalence of anti- Toxocara antibodies in a random sample of inpatients at a chidren's hospital in Vitoria, Espirito Santo, Brazil. Rev. Inst. Med. trop. S. Paulo, 40: 259-261, 1998.

12. OVERGAAUW, P.A.M. - Aspects of Toxocara epidemiology: human toxocarosis. Crit. Rev. Microbiol., 23: 215-231, 1997.

13. SCHANTZ, P.M. - Toxocara larva migrans now. Amer. J. trop. Med. Hyg., 41 (suppl.): 21-34, 1989.

14. VIRGINIA, P.; NAGAKURA, K.; FERREIRA, O. & TATENO, S. - Serologic evidence of toxocariasis in Northeast Brazil. Jap. J. med. Sci. Biol., 44: 1-6, 1991.

Received: 7 July 2003

Accepted: 13 October 2003

Francisco ANARUMA FILHO(1), Pedro Paulo CHIEFFI(2,3), Carlos Roberta S. CORREA(4), Eide Dias CAMARGO(5), Edilene P. Real da SILVEIRA(5) & Joana Jose B. ARANHA(5)

(1) Associacao Cultural e Educacional de Garca - ACEG, SP, Brasil

(2) Instituto de Medicina Tropical de Sao Paulo (LIM 06), Sao Paulo, SP, Brasil

(3) Faculdade de Ciencias Medicas da Santa Casa de Sao Paulo, Sao Paulo, SP, Brasil

(4) Departamento de Medicina Preventiva e Social, Faculdade de Medicina da UNICAMP, Campinas, SP, Brasil

(5) Instituto Adolfo Lutz, Sao Paulo, SP, Brasil

Correspondence to: P.P. Chieffi, Instituto de Medicina Tropical de Sao Paulo. Av. dr. Eneas de Carvalho Aguiar, 470, 05403-000 Sao Paulo, SP, Brasil. E-mail: pchieffi@usp.br

Return to Toxocariasis

Home

Contact

Resources

Exchange Links

ebay