THE FULL VISUAL GUIDE / 12 EXAMPLES
Every image below was checked against its public-health identification. Microscopy can show an egg, larva, cyst, blood stage, or only the head of a worm—not necessarily the entire parasite. Each card now tells you exactly what the image shows, how exposure can happen, and what infection may do.
Swallowing the parasite from contaminated water, food, hands, surfaces, or fecal contact. Untreated lake and stream water is a familiar risk.
May cause diarrhea, gas, greasy stools, cramps, nausea, and dehydration. Some infections cause no symptoms; prolonged illness can affect nutrient absorption.
Intestinal tapeworm usually follows eating raw or undercooked infected beef or pork. Swallowing T. solium eggs is a different exposure that can cause cysticercosis.
Often causes no symptoms or mild digestive upset, abdominal pain, appetite changes, weight loss, or passing segments. Cysticercosis can injure the brain, eyes, or muscles and cause seizures.
Swallowing microscopic eggs transferred from fingers, bedding, clothing, food, or household surfaces—especially around children and group settings.
Usually causes nighttime itching around the anus and disturbed sleep. Scratching can irritate or infect the skin; migration to the vaginal area can occasionally cause inflammation.
Swallowing eggs in soil or on produce contaminated with human feces, most often where sanitation is inadequate.
Many infections are silent. Larval migration can cause cough; intestinal infection may cause abdominal pain. Heavy infections can block the intestine and slow growth in children.
Larvae in soil contaminated with human feces can penetrate bare skin, commonly through bare feet. Some species may also be swallowed.
Can cause an itchy entry-site rash, abdominal symptoms, and intestinal blood loss. Heavier or prolonged infection may lead to iron-deficiency anemia and protein loss.
Swallowing eggs from soil, hands, food, or produce contaminated with human feces.
Light infections may cause nothing noticeable. Heavy infection can cause frequent painful stools, diarrhea, anemia, poor growth in children, and sometimes rectal prolapse.
Microscopic larvae in contaminated soil penetrate exposed skin, such as bare feet, and migrate to the intestine.
Often silent, but may cause rash, cough, abdominal pain, bloating, or diarrhea. In people taking immune-suppressing drugs—especially corticosteroids—it can become life-threatening.
Larvae penetrate skin during contact with contaminated freshwater in regions where schistosomiasis occurs; it is not caught from properly chlorinated pools.
Early infection may cause itchy skin, rash, fever, cough, or aches. Eggs can trigger long-term inflammation and scarring in the intestine, liver, bladder, or urinary tract.
Swallowing oocysts in contaminated pools, lakes, drinking water, food, or from fecal contact with infected people, calves, lambs, or goats.
Typically causes watery diarrhea, cramps, nausea, and dehydration. Illness can be prolonged or severe in people with weakened immune systems.
Swallowing cysts in food or water contaminated with feces, or through fecal exposure during sexual contact.
Most infections cause no illness. Amebic colitis can cause cramps, diarrhea, and bloody stool; rarely, the parasite spreads to the liver and causes an abscess.
Eating undercooked infected meat; swallowing the parasite after contact with contaminated soil, food, water, or cat feces; or transmission during pregnancy.
Usually silent or mildly flu-like in healthy people. New infection during pregnancy and infection in immunocompromised people can seriously affect the eyes, brain, or unborn child.
Usually transmitted by the bite of an infected female Anopheles mosquito in an area where malaria spreads.
Can cause fever, chills, headache, fatigue, and vomiting. P. falciparum can progress quickly to severe anemia, organ failure, brain complications, or death without prompt treatment.
These are possible exposure routes and medically recognized effects—not a symptom checklist and not proof of infection. Many infections cause no symptoms, while common conditions can cause similar complaints. A qualified healthcare professional can select appropriate stool, blood, imaging, or other testing. Explore CDC DPDx ↗
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