Parasitic worm infection
Soil-transmitted helminth infections are caused by different types of parasitic worms
It is transmitted through eggs in human feces, which contaminate soil in areas with poor sanitation
Approximately 2 billion people are infected with soil-borne parasitic worms worldwide
Infected children suffer from physical, nutritional and cognitive impairments
Control depends on the following:
Deworming regularly to get rid of the infection-causing worms
Health education to prevent re-infection
Improving sanitation to reduce soil contamination with infective eggs Availability of safe and effective infection control medicines
Soil-transmitted helminth infections are among the most common worldwide, affecting the poorest and most disadvantaged communities. It is transmitted by eggs in human faeces that contaminate soil in areas with poor sanitation. Roundworm (Ascaris lumbricoides), Ascaris worm (Trichum capillaris), hookworm (American lethal) and Ancylostoma are among the main types that infect people.
Soil-transmitted helminths are transmitted through eggs and are transmitted from the faeces of infected people. The adult worms live in the intestines, where they produce thousands of eggs daily, which pollute the soil in areas that lack adequate sanitation services. This happens in several ways:
Eggs stuck to vegetables are eaten when they have not been carefully cooked, washed or peeled
Eggs are eaten from contaminated water sources
Children who play in contaminated soil eat eggs and then put their hands in their mouths without washing them
In addition, hookworm eggs hatch in the soil, releasing larvae that mature into a form that can actively penetrate the skin. People primarily contract hookworm by walking barefoot on contaminated soil.
There is no direct person-to-person transmission, or infection from fresh faeces, because the eggs that pass through the faeces need about 3 weeks to mature in the soil before becoming infective. Since these worms do not reproduce in the host human, re-infection occurs only as a result of contact with the infectious phases in the environment.
Morbidity and symptoms
The morbidity is related to the number of worms that are being housed. People with mild infections usually don’t show any symptoms. Severe infection may cause a range of symptoms including bowel problems (diarrhea, abdominal pain), malaise, coughing, general weakness, cognitive impairment and physical development. Hookworms cause chronic intestinal blood loss, which can lead to anemia.
The worms feed on the host’s tissues, including the blood, which leads to a loss of iron and protein
Worms increase the malabsorption of nutrients. In addition, the roundworm may compete for vitamin A in the intestine.
Also, some parasitic worms transmitted through the soil may cause loss of appetite, which leads to reduced food ration and physical fitness.. Trichophyton cephalus can cause diarrhea and dysentery.
WHO control strategy
In 2001, delegates to the World Health Assembly unanimously passed a resolution (WHA 19.54) urging endemic countries to begin seriously treatment of worms, particularly schistosomiasis, and soil-transmitted helminths.
The strategy for controlling soil-transmitted helminth infections is to control morbidity through periodic treatment of at-risk people living in endemic areas. The people at risk are in the following categories:
school age children,
Women of childbearing age (including pregnant women in the second and third trimesters and during lactation),
Adults in some high-risk occupations.
WHO recommends regular medical (deworming) treatment without prior individual diagnosis for all people at risk in endemic areas. Treatment should be given once a year when the prevalence of soil-transmitted helminth infection in the community exceeds 20%, and twice a year when the prevalence of soil-transmitted helminth infection in the community exceeds 50%. This intervention reduces morbidity by reducing worm burden. In addition to the following:
Health and hygiene education reduces transmission and recurrence by encouraging healthy behaviours. Providing adequate sanitation facilities is an important but unattainable issue in resource-scarce environments.
Morbidity control aims to reduce the severity of infection and protect infected persons from disease through periodic treatment of at-risk populations.
Regular deworming can be easily integrated into child health days or supplementary feeding programs for preschool children, or combined with school health programmes. In 2013, more than 368 million school children were treated with anthelmintic drugs in endemic countries, which is equivalent to. 42% of all children at risk.
Schools provide a particularly good point for introducing deworming activities, as they provide a component of health and hygiene education such as promoting hand washing and improving sanitation.
WHO recommended medicines
WHO-recommended medicines such as albendazole (400 mg) and mebendazole (500 mg) are effective, inexpensive and easy for non-medical personnel to use. Extensive testing has been done to determine their safety and has already been used by millions of people with very few minor side effects.
Both albendazole and mebendazole are donated to national ministries of health through WHO in all endemic countries for the treatment of all school-age children.
Prof.Dr. Zainab Ali Hussein