Parasites are organisms that cannot continue their life cycle without a host. Parasites can trigger many diseases in humans. They can occur in the form of ten-centimeter worms or single-celled amoebae.
A parasite is a living organism that can only live and grow inside another organism. Parasites invade cells, food, tissues, etc. uses it to grow and reproduce. All parasites can only survive by parasitizing another organism, but not every microorganism that parasitizes one organism is necessarily a parasite. For example, viruses live as parasites, but they are not parasites.
Parasites consisting of a single cell are called protozoa. They live on their own, not in colonies. Multicellular parasites are metazoans. Generally these are worms that can thrive in a reasonable environment. They can develop under the skin in the digestive tract, liver, and even the heart.
They have a wide variety of forms, they can be found in a round form such as a pinworm, or in a flat form such as a flatworm. Like mites, they are small microscopic insects that cannot be seen with the naked eye.
In the middle of these are the parasites that cause the most damage to the human body. Here are the 7 most damaging parasites.
Paralyzing the muscles: Australian tick
Ixodes holocyclus, an endemic genus in Australia, can cause paralysis. The tick, which first manifests itself with vomiting, then affects with loss of muscle strength in the lower extremities. The paralysis then occurs within 24 hours and gradually spreads to the rest of the body.
If the tick is not removed quickly, damage to the breathing and swallowing muscles can lead to death. Human events are rare, but more than 100,000 pets are claimed to be affected each year.
Eating the ear from the inside: Wohlfahrtia magnifica
Wohlfahrtia magnifica causes myiasis (worming of the skin) that mostly affects the ear. The larvae invade the eardrum and then attack the wall of the inner ear and sometimes the brain, which can lead to death. The maggot can also attack the eyes and destroy the eyeball.
They cause a feeling of something moving under the skin. Maggots of about 10 millimeters come out after a few days, but they can cause edema or allergic shock.
It leaves scars: Leishmania
Leishmania is a microorganism that causes leishmaniasis. It is transmitted to humans when bitten by a midge, a genus of small mosquitoes. Leishmania is then engulfed by cells, where it loses its flagellum and turns into an amastigote.
Symptoms differ depending on the position of the infected cells. They can develop large crusts that can leave indelible scars on the skin. The most important visceral form is manifested by fever, weight loss, swelling of the liver, spleen and lymph nodes. It is fatal if not treated.
Causes elephant disease: Wuchereria bancrofti
Elephant disease causes massive swelling of the limbs. It is caused by infection with three types of worms, including Wuchereria bancrofti, which causes 90 percent of cases.
Wuchereria bancrofti produces millions of tiny larvae called microfilariae, which are transmitted by mosquitoes. They enter the lymphatic system and, as adults, can cause tissue swelling and thickening of the skin in the limbs.
According to the World Health Organization, one out of every three infected people experiences a disabling condition.
Causes blindness: Onchocerca volvulus
Caused by the worm Onchocerca volvulus, onchocerciasis affects the skin and eyes. Affecting 30 African countries, this form is the fourth leading cause of blindness in the world.
When this parasite migrates to the eye and dies there, it causes an inflammatory response that will cloud the eye. Millions of people are still considered at risk. In addition, there is another form of onchocerciasis that causes severe dryness and premature aging of the skin.
Eating the brain: Naegleria fowleri
Naegleria fowleri, known as the brain-eating amoeba, is an amoeba that lives in the warm waters of lakes, swamps or neglected swimming pools. It is the cause of primary amoebic meningoencephalitis, a crucial condition that is fatal in 95 percent of cases.
Infection occurs by direct contact with water or by inhaling water droplets carried by the wind. The amoeba infiltrates the nose and then migrates to the brain. Headache, vomiting and fever occur after 1 to 9 days, followed by confusion and hallucinations.
The disease is scarce, with 310 events recorded worldwide in 50 years.
Invading the lungs: Ascaris
It is a colorful roundworm that can grow up to 30 cm in length. It is transmitted by consuming contaminated water or food. The female lives in the small intestine, feeds on what the person eats, and can lay up to 200,000 eggs a day. They free the embryos that cross the digestive wall and reach the liver and then, in some cases, the lungs via the blood circulation. They then cause Löffler syndrome with pulmonary opacity, cough and fever.
The most important complications are acute pancreatitis with appendicitis. Ascariasis is the most common intestinal parasite in the world, affecting a quarter of the world’s population, mainly in developing countries.