Helminths are parasitic worms. Worms can be transmitted to humans in fecal material, from insects or from walking barefoot on contaminated soil.
Most helminths are either roundworms or flatworms. Once they enter the body, they tend to live in the intestines. Parasitic worms make up the majority of neglected tropical diseases.
Roundworms live in the soil and are the biggest contributor of human illnesses in the developing world. Around 3 billion people are chronically infected with these worms across the globe and can contribute to the development of asthma. Other symptoms caused by the worms include itching, diarrhea, constipation, and nausea.
The worms grow best in warm climates. Poor hygiene and poverty can contribute to developing disease from these parasites.