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Introduction:

Intestinal parasitic diseases are still prominent in the tropical and subtropical areas of the world and are more common in undeveloped or developing nations. The prevalence of intestinal diseases in different areas and countries can indirectly reflect the local sanitation conditions and living conditions.

Types of Parasites:

Intestinal parasites can be categorized into two types—protozoa and worms. Common protozoa include amoeba, Giardia lamblia, and Cryptosporidium hominis. On the other hand, common parasitic worms include roundworms, hookworms, whipworms, pinworms, human liver flukes (Clonorchis Sinensis), and tapeworms.

Transmission Route:

1. Different intestinal parasites are transmitted to humans differently. Generally, humans acquire intestinal parasites through either ingestion of parasites such as roundworm, whipworm, liver fluke, tapeworm, and amoeba or skin penetration by infective larvae of parasites such as duodenal hookworm, American hookworm (through contact with contaminated soil).
2. Most intestinal parasites are introduced into the human body through the mouth. Parasites present in the intestinal tract lay eggs that are later excreted in human feces, which directly contaminate the soil or are indirectly transmitted into the soil, vegetables, fruits, or water sources through fertilization. In addition, poor diet or hygiene habits (such as eating or drinking uncooked foods or not washing hands before eating) can also cause infection by consuming parasite eggs.
3. Liver flukes and tapeworms require one or multiple intermediate hosts for transmission to humans. For example, they can be contracted by eating undercooked meat (such as pork, beef, or fish) that is already contaminated with parasite larvae.

Symptoms:

1. Symptoms vary depending on the type of parasite infections. Common nematode (such as roundworms, hookworms, whipworms, etc.) infections may result in symptoms such as abdominal discomfort, diarrhea, vomiting, malnutrition, or weight loss. If infected with a large number of parasites, intestinal blockage, anemia, bile duct blockage, or other inflammatory symptoms may occur. Pinworm infection often leads to symptoms such as loss of appetite, amnesia, irritation, and itching around the anal area.
2. 90% of the people infected with amoebae do not show any symptoms. However, the infected person may also intermittently infect others. The other 10% may experience mild abdominal discomfort, intermittent diarrhea, or constipation along with parasite colonization of the intestinal wall. More severe cases may experience fever, shivering, bloody stool, or soft mucus stool. In addition, secondary infection may occur, and a liver abscess is the most commonly secondary to an infection, more than lung abscess and brain abscess.
3. Symptoms of tapeworm infections include abdominal cramps, loss of appetite, nausea, malnutrition, and weight loss. Tapeworm eggs found in pork hatch in the host’s small intestines, and then migrate to other organs and tissues, leading to cysticercosis. Cysticercosis commonly occurred under the skin or between muscle layers with no apparent symptoms. However, if cysticercosis occurs in the brain, eyes, or spine, the complications will be more severe.
4. Mild infections of human liver flukes (Clonorchis Sinensis) do not show apparent symptoms. Chronically, symptoms such as loss of appetite, weakness, discomfort in the upper abdomen, diarrhea, indigestion, pain in the upper right abdomen, and hepatomegaly will start to appear. If the infection is heavy, bile duct blockage, bile duct inflammation, or jaundice may occur. Further, long-term infection may induce symptoms such as gallstones or even liver cirrhosis or cancer.

Diagnosis method: 

Fecal samples are collected to examine for the presence of parasite eggs, protozoa. or parasites.

Treatment:

Different intestinal parasite infections require different treatments. Therefore deworming medication should be used only with a doctor’s prescription.

Preventive measures:

1. Do not consume uncooked food (including vegetables, pork, beet, and fish). Fruits and melons should be washed thoroughly before consumption.
2. Boiled water is safer to drink.
3. Pay attention to personal hygiene. Clip fingernails regularly and wash hands before meals and after defecating.
4. Do not defecate outdoors; do not use fresh fertilizers; excretions should be processed through septic tanks in order to prevent contamination of water sources.
5. Daycares and elementary schools should conduct regular parasite inspections to detect any infected child as early as possible and then administer deworming treatment.
6. If you experience any suspicious intestinal parasite symptoms, please seek medical assistance in identifying the illness and receiving treatment immediately.
7. Most patients infected with intestinal parasites do not show any symptoms or experience only mild symptoms. However, they are still infectious and may intermittently excrete parasite eggs. Therefore, it is hard to detect traces of the parasite with only one inspection. Regular examination and early treatment are highly recommended.

Communicable Disease Reporting and Consultation Hotline: 1922
Centers for Diseases Control Website: littp://www.cdc.gow.tiN