DNA Barcoding as a Diagnostic Tool of a Rare Human Parasitosis: The First Case of Lagochilascaris minor in Quintana Roo, Mexico.

Recently, DNA barcoding based on the mitochondrial gene cytochrome c oxidase subunit 1 (COI) has become a widespread tool to identify animals. Its use with parasites of humans has been limited with some groups of nematodes where the amplification of this gene has been difficult. In this study, we present the first COI barcode sequence of a rare parasite from tropical regions, Lagochilascaris minor, which parasitized a human host from Quintana Roo, southern Yucatán Peninsula, Mexico. Destruction of the mastoid apophysis in the lateral sinus and cerebellar involvement were observed at the site of infection. After a radical mastoidectomy and a treatment with 200 mg oral albendazole for 63 days, the patient completely recovered. Lagochilascaris minor was identified based on the ratio between length of spicules and ejaculatory duct, shape of eggs, and host, as well as comparison with its congeners. The mode of infection is unknown, although it could be after direct exposure to eggs or consumption of uncooked wild meat. Morphology of adults is demonstrated using scanning electron microscopy, and high-quality sequences of COI barcode are presented from amplifications using semi-degenerate primers designed for micro-crustaceans. DNA barcoding proved to be a reliable identification method for L. minor. A comparison of the sequences for this species with 81 ascaridoids obtained from the Barcode of Life Database places it in a unique clade most closely related to Baylisascaris procyonis. Future diagnosis of larval and adult stages of L. minor using DNA barcoding will allow the recognition of its infection parameters, transmission, and precise epidemiology. Reports of lagochilascarosis in the Yucatán Peninsula have been occurred over the last decade, suggesting it is an emerging zoonotic disease in the region.

An ultrasonographic scoring method for transabdominal monitoring of ascarid burdens in foals.

REASONS FOR PERFORMING STUDY: Parascaris spp. infections can lead to life-threatening small intestinal impactions in foals. Currently available diagnostic techniques cannot estimate the magnitude of an ascarid burden, and hence identify foals potentially at risk of developing impactions. OBJECTIVES: To describe and evaluate an ultrasonographic transabdominal scoring technique for monitoring of ascarid burdens in foals and to perform a cost-benefit analysis of the application of this technique. STUDY DESIGN: A transabdominal ultrasonographic technique was validated against ascarid worm counts from 10 foals aged 162-294 days. In a treatment trial, 15 foals were randomly allocated to 3 treatment groups: ivermectin, oxibendazole and no treatment. Blinded ultrasound examinations were performed daily for 5 consecutive days following treatment. Foals were examined ultrasonographically twice by the same investigator, and by different investigators for intra- and interobserver agreement evaluation. Cost-benefit analyses identified threshold values for the probability of ascarid impactions above which the screening method becomes cost-effective. METHODS: The ultrasound technique used 3 locations along the ventral midline. An ascarid scoring system was established that assessed the magnitude of ascarid burden ranging from 1-4. The method was validated against worm burdens of 10 worms and above with calculation of diagnostic specificity, sensitivity, and predictive values. Treatment trial data were evaluated statistically using mixed model analysis. Kappa values were generated for intra- and interobserver agreement. RESULTS: Two consecutive examinations were found to detect worm burdens >10 ascarids reliably. Ascarid scores declined in response to both anthelmintic treatments, although differences were not statistically significant. Kappa values indicated fair to moderate intra- and interobserver agreements. The majority of cost-benefit analyses indicated that ultrasound examinations are cost effective when the probability of ascarid impactions is above a range of 0.0001-0.0082 (i.e. 1 in 10,000 to 8 in 1000 foals). CONCLUSIONS: The ultrasonographic screening techniques can be a useful tool for monitoring ascarid burdens in foals.