Determining Soil-transmitted Helminth Infection Status and Physical Fitness of School-aged Children

Summary

Chronic infection with soil-transmitted helminths (STHs) causes malabsorption, stunting, and wasting in the growing child. Hence, it is plausible that these infections also reduce the physical fitness of children. Here, we visualize two techniques for the diagnosis of STHs and the 20-meter shuttle run test for assessing children's physical fitness.

Abstract

Soil-transmitted helminth (STH) infections are common. Indeed, more than 1 billion people are affected, mainly in the developing world where poverty prevails and hygiene behavior, water supply, and sanitation are often deficient^1,2. Ascaris lumbricoides, Trichuris trichiura, and the two hookworm species, Ancylostoma duodenale and Necator americanus, are the most prevalent STHs³. The estimated global burden due to hookworm disease, ascariasis, and trichuriasis is 22.1, 10.5, and 6.4 million disability-adjusted life years (DALYs), respectively⁴. Furthermore, an estimated 30-100 million people are infected with Strongyloides stercoralis, the most neglected STH species of global significance which arguably also causes a considerable public health impact^5,6. Multiple-species infections (i.e., different STHs harbored in a single individual) are common, and infections have been linked to lowered productivity and thus economic outlook of developing countries^1,3.

For the diagnosis of common STHs, the World Health Organization (WHO) recommends the Kato-Katz technique^7,8, which is a relatively straightforward method for determining the prevalence and intensity of such infections. It facilitates the detection of parasite eggs that infected subjects pass in their feces.

With regard to the diagnosis of S.stercoralis, there is currently no simple and accurate tool available. The Baermann technique is the most widely employed method for its diagnosis. The principle behind the Baermann technique is that active S.stercoralis larvae migrate out of an illuminated fresh fecal sample as the larvae are phototactic⁹. It requires less sophisticated laboratory materials and is less time consuming than culture and immunological methods⁵.

Morbidities associated with STH infections range from acute but common symptoms, such as abdominal pain, diarrhea, and pruritus, to chronic symptoms, such as anemia, under- and malnutrition, and cognitive impairment¹⁰. Since the symptoms are generally unspecific and subtle, they often go unnoticed, are considered a normal condition by affected individuals, or are treated as symptoms of other diseases that might be more common in a given setting. Hence, it is conceivable that the true burden of STH infections is underestimated by assessment tools relying on self-declared signs and symptoms as is usually the case in population-based surveys.

In the late 1980s and early 1990s, Stephenson and colleagues highlighted the possibility of STH infections lowering the physical fitness of boys aged 6-12 years^11,12. This line of scientific inquiry gained new momentum recently^13,14,15. The 20-meter (m) shuttle run test was developed and validated by Léger et al.¹⁶ and is used worldwide to measure the aerobic fitness of children¹⁷. The test is easy to standardize and can be performed wherever a 20-m long and flat running course and an audio source are available, making its use attractive in resource-constrained settings¹³. To facilitate and standardize attempts at assessing whether STH infections have an effect on the physical fitness of school-aged children, we present methodologies that diagnose STH infections or measure physical fitness that are simple to execute and yet, provide accurate and reproducible outcomes. This will help to generate new evidence regarding the health impact of STH infections.

Protocol

1. Kato-Katz Technique

1. Place a standard Kato-Katz template with a hole for holding 41.7 milligrams (mg) of stool on a microscope slide.
2. Scoop 2-3 grams (g) of a fresh fecal sample onto a piece of newspaper or aluminum foil, and press a piece of wire or plastic mesh on top to sieve it.
3. Using a small plastic spatula, scrape the sieved material off the mesh and completely fill the hole in the Kato-Katz template with it. To remove excess fecal material, level the content of the hole with the spatula.
4. Vertically remove the template without disturbing the fecal material now adhering to the microscope slide. The template and spatula ....

Discussion

The three protocols described in this paper have been tested and executed in the south-western part of Yunnan province, People's Republic of China among members of the Bulang ethnic minority²¹ and in different parts of Africa^6,13,14.

There are several templates available for the Kato-Katz technique. Each distinct hole-size will deliver a distinct amount of fecal material. For the calculation of EPGs, it is therefore necessary to know the unit of the template, so as to mul.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Note: Materials in this list are generic and can be obtained from different sources.
Kato-Katz kit [400 plastic templates with a hole of 6 millimeter (mm) (diameter) in a 1.5 mm thick template; 400 plastic spatula; a 20-m role of nylon screen of 80 mesh size; a 20-m role of hydrophilic cellophane, 34 μm thick.]	Vestergaard Frandsen		Please note that the glycerin-malachite green solution is not included in this kit but can be bought from any chemical supplier.
Glass funnel [about 8 centimeter (cm) wide and 6 cm deep]			The glass funnel for the Baermann technique should be able to hold about 60 mL of water. The size of the rubber hose and gauze is dependent on the type of glass funnel used.
Biological microscope	Olympus	CX21LED/CX21
Centrifuge	Shanghai Medical Instruments Group	80 - 2T
Pre-recorded signals	Bitworks Design	Team Bleep Test Version 1.3.1	iPhone application
Heart rate monitor	POLAR	FT1	Watch and transmitter