Serodiagnosis of Toxocara among Infants and Pregnant Women Suspected of Ocular or Visceral Toxocariasis Using Two Types of ELISA Antigens

Document Type: Original Article

Author

Department of Parasitology, Research Institute of Ophthalmology, Cairo, Egypt

Abstract

Background: The diagnosis of toxocariasis heavily depends on immunological tests because the number of parasites is usually few in infected tissues, unless they migrate into an organ such as eye. In general, patients with ocular toxocariasis have serum anti- T canis antibody titres that are significantly lower than those with visceral toxocariasis.
Objective:
To diagnose the asymptomatic toxocariasis in infants before
two years old and suspected pregnant women by an ELISA method utilizing two different antigens of TEE and capture TEX.
Methods:
This work was carried out between
8/2005 and 4/2006. Specimens of serum collected from 79 infants (apparent healthy) aged between 4 weeks to 30 moths (51 females and 28 males) Also, 28 specimens of serum were collected from asymptomatic pregnant women aged between 18-32 years old and all their infants (17 females and 11 males that their ages were as mentioned above). Serodiagnosis by ELISA was done by using two antigens, Toxocara canis embryonated egg antigen (TEE) and Toxocara canis antigen capture ELISA .
Results:
Toxocara antibodies were found in 7 and 12 pregnant women,
when tested by TEE and capture TEX ELISA respectively. Three out of 28 and 7 out of 28 infant sera were positive for Toxocara antibodies when tested by TEE ELISA and capture TEX ELISA respectively. Active ocular toxocariasis was only diagnosed in the left eye of one mother. All inactive ocular toxocariasis were diagnosed by capture TEX ELISA, except one infant serum, which was diagnosed by TEE ELISA.
Conclusion: The capture TEX ELISA was able to discriminate positive and negative toxocariasis samples better than TEE ELISA. In addition, sample analyses by both capture TEX ELISA and TEE ELISA is recommended in children and young adults, when toxocariasis is considered in the differential diagnosis of the ocular diseases.

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