Parasites are organisms that live on or inside another organism, known as the host, and rely on the host for their survival. Unfortunately, humans can fall victim to a variety of parasites, some of which can cause severe harm or even death.

In this article, we will explore the top 10 most dangerous parasites found in humans.

1. Malaria Parasite (Plasmodium falciparum)

Malaria, caused by the Plasmodium falciparum parasite, is one of the deadliest infectious diseases globally.

Transmitted through the bites of infected mosquitoes, this parasite invades red blood cells and causes flu-like symptoms, including high fever, chills, and body aches. If left untreated, malaria can lead to organ failure and death.

2. Human Botfly (Dermatobia hominis)

The human botfly lays its eggs on mosquitoes and other biting insects. When the infected insect bites humans, the body heat causes the eggs to hatch, and the larvae burrow into the skin.

This can lead to painful skin lesions, infections, and even tissue damage if not removed promptly.

3. Guinea Worm (Dracunculus medinensis)

The guinea worm parasite is transmitted through contaminated drinking water. After ingestion, the larvae mature and mate in the human body.

The female worm, measuring up to three feet long, eventually emerges through painful blisters in the skin, such as the lower limbs. This process can cause excruciating pain, secondary infections, and disability.

4. Toxoplasma gondii

Toxoplasma gondii is a parasite commonly found in cat feces and raw or undercooked meat. Infections are usually asymptomatic but can lead to severe complications in individuals with weakened immune systems or during pregnancy.

In pregnant women, this parasite can cause miscarriage or birth defects in the fetus.

5. Naegleria fowleri

Naegleria fowleri, also known as the “brain-eating amoeba,” is a free-living amoeba found in warm freshwater and soil.

When contaminated water enters the nose, the amoeba can reach the brain, causing a rare but often fatal infection called primary amoebic meningoencephalitis (PAM).

6. Leishmania

Leishmania parasites are transmitted through the bites of infected sandflies. They cause a range of diseases collectively known as leishmaniasis. Depending on the specific species, leishmaniasis can manifest as cutaneous, mucocutaneous, or visceral forms.

Visceral leishmaniasis is particularly dangerous, affecting the internal organs and potentially leading to death if left untreated.

7. Schistosoma

Schistosomiasis, also known as snail fever, is caused by infection with parasitic flatworms of the genus Schistosoma.

The larvae of these worms are released into freshwater by specific snail hosts, and human infection occurs through direct contact with the contaminated water. Schistosomiasis can cause chronic inflammation, which leads to organ damage in the intestines, liver, bladder, and lungs.

8. Taenia solium

Taenia solium, also called the pork tapeworm, is acquired by consuming undercooked pork containing cysts. Once ingested, the tapeworm attaches itself to the intestines and can grow up to several meters long.

Infection with Taenia solium can lead to severe complications, including neurocysticercosis, where cysts form in the brain and can cause seizures and neurological damage.

9. Loa loa

The Loa loa parasite, transmitted through the bites of infected deerflies and mango flies, causes a condition known as loiasis or African eye worm. Adult worms can move beneath the skin and even across the eyeball.

While usually non-life-threatening, loiasis can cause significant discomfort, pain, and inflammation.

10. Toxocara canis

Toxocara canis is a roundworm commonly found in dogs. Human infection occurs through ingestion of the parasite’s eggs, usually from contaminated soil or unwashed fruits and vegetables.

The larvae can migrate throughout the body, leading to a condition called visceral larva migrans. Symptoms may include fever, cough, liver enlargement, and, rarely, eye complications.