A Simple Fecal Flotation Method for Diagnosing Zoonotic Nematodes Under Field and Laboratory Conditions

Summary

This work describes the use of a flotation method to identify Toxocara canis and Ancylostoma spp. detected in fecal samples collected from dogs in Mexico from 2017 to 2021 under field conditions.

Abstract

Diagnosis of canine parasites with zoonotic potential such as Toxocara canis and Ancylostoma caninum under field conditions is usually difficult due to limited access to a laboratory in rural and suburban areas in Mexico. This study aimed to detect T. canis and Ancylostoma spp. in fecal samples collected from dogs in Mexico from 2017 to 2021 under field conditions. Sample size calculation resulted in a target enrollment of 534 dogs across the country.

Samples were collected directly from the rectum or the ground after defecation. Samples were stored in individual, tightly sealed, plastic bags at 4 °C. A saturated solution of sodium chloride (specific gravity [SpG] 1.20) was prepared both under field and laboratory conditions. Within 3 days of collection, 2-4 g of feces were tested for parasites using a flotation method by suspending each fecal sample in a saline solution. Feces were mixed with the flotation solution and crushed using a metal spoon.

Once a uniform consistency was achieved, the fecal sample was poured into a new plastic cup using a sieve and allowed to sit for 10-15 min. Three drops from the top of the mixture were collected using a sterilized inoculating loop. The slides were placed on the microscope and parasites were identified by trained parasitologists. Fecal samples from 1,055 dogs were screened microscopically. The number of positive samples for Ancylostoma spp. was 833 (78.95% frequency) and 222 (21.04%) for T. canis. These findings illustrate the importance of identifying zoonotic helminths in dogs living in urban and rural areas in Mexico using a coproparasitoscopic technique in the laboratory and under field conditions.

Introduction

Gastrointestinal parasites are one of the most common health problems that affect dogs¹. Estimates suggest that there are ~700 million domestic dogs worldwide, and approximately 175 million may be categorized as free-roaming². More than 60 parasite species are shared between dogs and humans, suggesting that dogs could be a source of infection for humans with these parasites³. Toxocara canis and Ancylostoma caninum are two parasitic species that infect dogs and, accidentally, human hosts. Currently, there are several studies about the locations where these helminths are able to su....

Protocol

The use and care of dogs was approved by the National and Autonomous University of Mexico.

1. Collection of fecal samples

NOTE: Handle the dog with the help of a veterinarian or the owner of the animal.

1. In the case of feral dogs (Figure 1A) or nervous animals, collect samples from the ground right after defecation or no more than 10 min later.
2. Lubricate surgical gloves or thin-walled polyethylene b.......

Discussion

Nematodes such as T. canis and Ancylostoma spp. can inhabit the small intestine of dogs and have the potential to be transmitted to humans. Clinical signs caused by T. canis are serious in young dogs, manifesting as poor growth, respiratory issues, or digestive tract lesions²⁸. In adult dogs, the infection typically tends to be mild. Diagnosis relies on identifying characteristic eggs in a fecal sample. This condition is a frequent cause for prescribing anthelmintic trea.......

Materials

Name	Company	Catalog Number	Comments
3 x 1.2 V AA rechargeable batteries	Energizer		Sold in retail stores
Bunsen burner	Viresa	FER-M224
Disposable 12-oz glass cup	Uline Mexico	S-22275	Sold in retail stores
Glass slides	Velab, Mexico	VEP-P20
Inoculating loop	VelaQuin, Mexico	CRM-5010PH
Light Microscope	VelaQuin, Mexico	VE-B2
Lighter	Bic	J25	Sold in retail stores
One plastic cup (12 oz)	Amazon	ASIN B08C2CRHSH	Can be any kitchen plastic reuseable cup
Plastic cups  (size of a dice or urine sample cup) diameter 5.5 cm and height 8.5 cm, two cups	Amazon	Layhit-Containers-ZYHD192919	Can be any kitchen plastic reuseable cup
Plastic strainer 10 cm	Ecko	ASIN B00TUAAVWI	Can be any kitchen plastic strainer
Soda bottle	Coca-Cola	1-liter	Sold in retail stores
Spoon	Amazon Basics	ASIN B00TUAAVWI	Can be any kitchen spoon
Table salt	La Fina		Sold in retail stores