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Soil-Transmitted helminths
Soil-transmitted Helminths (STH) are gastrointestinal nematodes that include roundworms, whipworms and hookworms. They are a group of intestinal parasites that are primarily transmitted through the consumption of contaminated soil. They directly infiltrate the human as their primary host, and do not require any intermediate host before infecting humans. They are found in areas with limited access to proper hygiene and sanitation. It is also common in places where human feces are used as a fertilizer. Most cases occur in hot, humid climates; primarily found in tropical and subtropical areas in Asia, sub-Saharan Africa and the Americas. It is rarely found in well developed areas. STHs are considered a Neglected-Tropical Disease because of their infliction of high disability yet are able to be eradicated and controlled.

Prevalence
There are three primary types of soil transmitted helminths:


 * 1) Ascaris intestinal roundworms, associated with the infection Ascaris Lumbricoides
 * 2) Whipworms, also known as Trichuris Trichiura
 * 3) Hookworms, associated with the infections Ancylostoma Duodenale & Necator Americanus

Infection prevalence is a measure of how many people in a community are infected. Their prevalence follows accordingly worldwide: Ascaris affect 807-1,121 million people, whipworms affect approximately 604-795 million people and hookworms affect approximately 576-740 million people. Morbidity is directly correlated to the worm burden; the severity of sickness is directly proportional to the number of worms present in the affected individual.

Their morbidity rate includes respectively:


 * Ascaris infect 350 million with a mortality rate of 60 thousand individuals
 * Whipworms infect 220 million with a mortality rate of 10 thousand individuals
 * Hookworms infect 150 million with a mortality rate of 65 thousand individuals

Global Distribution of Soil-transmitted Helminths (WHO)
Twenty-four percent of the world's population, upwards of 1.5 billion people, are infected with soil-transmitted helminths. The most prominent infected distributed areas are found in tropical or subtropical regions, notably occurring in sub-Saharan Africa, the Americas, China and East Asia. Any person in contact with contaminated soil in a tropical or subtropical environment with poor sanitation is at risk of getting this infection. Approximately 267 million preschool-aged and 568 million primary school-aged children reside in environments where these parasites are most prevalent.

Disease
Soil-transmitted helminths thrive in the intestine of the human host and pass their eggs through infected feces. These eggs are deposited in soil when an infected person defecates outside, or when infected feces are used as fertilizer. These eggs have the best survival rate in warm, humid areas as they must develop and grow in the soil before being able to infect others. Humans can become infected through two types of transmission: ingestion or penetration of the skin.

Only Ascaris and Whipworms eggs become infective in soil. Once Ascaris and whipworm eggs have matured in soil, they become infectious to anyone who ingests embryonated eggs. This can occur when contaminated dirt-covered hands or fingers are placed in the mouth, or while eating vegetables and fruits that have not been thoroughly cooked, washed, or peeled. On the other hand, hookworm eggs are not infectious. This species hatches their eggs in soil, releasing larvae that mature to form the ability to penetrate the skin of humans. This transmission primarily occurs by walking barefoot on contaminated soil. Reinfection occurs exclusively as a result of contact with infective stages in the environment since these parasites do not proliferate and multiply in the human host.

Symptoms
People infected rarely show symptoms, but if they do, they are typically light and show abdominal discomfort and cramping, nausea, appetite loss, and irregular stools. Patients can also experience a cough and wheezing due to the migration of the worm moving through the lungs and mitigating through the body. Severe infections of Ascaris and Whipworms can cause intestinal blockages and impair growth in children due to a loss of appetite. This impairment of nutritional status can be altered by worms feeding on human host tissues, including blood, attributing to iron and protein deficiency. Hookworms are also able to cause anemia provoked by chronic intestinal blood loss. In addition, STHs increase malabsorption of nutrients and deplete the host’s appetite, as a result reducing nutritional intake as a whole.

General impact of Soil-transmitted helminths
STH infections are a neglected-tropical disease, they thrive in poverty. These illnesses cause a great deal of death and suffering, contributing to poverty propagation by inhibiting children's physical and intellectual development, as well as adults' job capability and productivity.

Children are especially vulnerable to suffer from gastrointestinal nematode related morbidity due to their inclination of playing outside and consuming foriegn contaminated objects. Children grow rapidly and are especially susceptible to infection and the associated morbidity. The World Health Organization has released a helminth control programme for school-aged children that plans, implements, monitors, and evaluates treatment for soil-transmitted helminths. The program is heavily based on the implementation of drug treatment known as deworming. The purpose of this program is to improve the environmental conditions where STH infections thrive and alter the risk behaviors associated. Deworming, improved hygiene and sewage, and health education are critical components of the school-based control program that can minimize the spread of  STH infections and avoid the emergence of related morbidity. Regular medication treatment is vital in a first-line quick control approach when the intensity of the infection is severe. Improved water and sanitation, as well as health education, should be applied in conjunction with the epidemiological situation and available resources.Without these advances, the infection prevalence is able to revert to pre-treatment levels within a few months of a deworming session. As a result, the deworming procedure must be done on a regular basis to control the reduction of the worm burden.

In accordance with the WHO helminth control program, the beneficence of recurring treatment consists of:


 * Reducing the amount of people heavily infected;
 * Minimize environmental soil contamination and risk of infection for others;
 * Decrease micronutrient loss through providing supplements (inducement of iron loss and deficiency caused by intestinal bleeding in hookworm infections);
 * Ameliorate nutritional status;
 * Refine cognitive functions and education on the matter.

Treatment
The medications used for treatment are proven effective, easy to administer and economical. These drugs have undergone comprehensive safety testing utilized by millions of people with slim to none side-effects. Table 1.1 summarizes the approved current treatments used in public health interventions.

Table 1.1 Drugs recommended for large scale school-children deworming program for Soil-transmitted Helminths The implementation of control measures for soil-transmitted helminths has made significant advances over the last decade. This has been driven by improved coordination of government commitment, as well as increased donor financing. In 2010, the WHO 2020 NTD Roadmap goal was to give regular anthelmintic treatment to at least 75 percent of children in places where infection frequency among children aged 5–14 years constituted greater than 20%. By 2018, Sub-Saharan Africa had essentially achieved this objective, with an approximate 70% of children receiving regular deworming.