Parasites Worms

Blastocystis hominis is a common protozoan parasite found in the intestines and is often detected in individuals experiencing gastrointestinal symptoms. While its role in causing illness remains disputed, it is frequently associated with various digestive problems and is commonly identified in stool tests worldwide.

Cryptosporidium spp. are a group of protozoan parasites that cause cryptosporidiosis, an infectious gastrointestinal disease. Known for their resilience in various environments, especially in water, these parasites play a key role in outbreaks of diarrhoeal illness affecting both humans and animals.

Cyclospora cayetanensis is a microscopic protozoan parasite that causes cyclosporiasis, an intestinal infection characterised by prolonged and recurring diarrhoea. It is commonly found in tropical and subtropical regions and has been linked to numerous foodborne outbreaks worldwide.

Dientamoeba fragilis is a single-celled parasite that inhabits the human gastrointestinal tract. It is associated with dientamoebiasis, a condition that can cause a range of digestive symptoms. Its precise mode of transmission and role in the disease are still being researched.

Dwarf tapeworms (Hymenolepis nana) are common parasites that infect humans, particularly children. They are unique because they can complete their entire life cycle within a single host, allowing direct transmission without the need for an intermediate host. While infections are often asymptomatic, they can cause abdominal pain, diarrhoea, and in severe cases, weight loss and malnutrition.

Entamoeba histolytica is a protozoan parasite responsible for amoebiasis, an infection that can range from mild or asymptomatic to severe forms, including dysentery and liver abscesses. It is a major public health concern in regions with poor sanitation, particularly in tropical and subtropical countries.

Enterocytozoon and Encephalitozoon species are microsporidia — spore-forming unicellular parasites that can infect humans. They can cause gastrointestinal and systemic diseases, particularly in people with weakened immune systems. Symptoms vary depending on the site of infection but commonly include diarrhoea, weight loss, and fatigue.

Flatworms and tapeworms are parasitic worms that can infect the human digestive system, most commonly through the consumption of undercooked or contaminated meat. Tapeworms belong to the class Cestoda and can grow several metres long inside the intestines. Once inside the host, they attach to the intestinal wall and absorb nutrients, often causing symptoms such as digestive problems, weight loss, or fatigue. In many cases, however, the infection can be asymptomatic and remain undetected for long periods. Diagnosis typically involves stool sample analysis to detect eggs or worm segments.

Giardia lamblia is a protozoan parasite that causes giardiasis, an intestinal infection characterised by diarrhoea and digestive discomfort. Known for its resilience, it can survive in harsh environments, especially contaminated water, making it a common source of waterborne outbreaks.

Hookworms are parasitic worms that inhabit the small intestine and feed on the host’s blood. They are commonly found in areas with poor sanitation and can cause anaemia, protein deficiency, abdominal pain, diarrhoea, and fatigue. Infection typically occurs through skin contact with soil contaminated by hookworm larvae.

Microsporidia are a group of microscopic, spore-forming parasites that primarily infect the intestinal tract but can also affect the eyes, muscles, and other organs, especially in individuals with weakened immune systems. These organisms are classified as fungi or fungus-like and are known to cause a condition called microsporidiosis. Transmission typically occurs through ingestion of contaminated food or water, or contact with infected animals or surfaces. Symptoms can include chronic diarrhea, weight loss, fatigue, and abdominal discomfort.

New World hookworms (Necator americanus) are a type of parasitic worm commonly found in the Americas. These parasites attach to the intestinal walls of their hosts, causing chronic blood loss, anaemia, and protein deficiency. The larvae can penetrate the skin from contaminated soil, putting individuals who come into contact with such environments at risk of infection.

Pinworms (Oxyuris), also known as threadworms, are common intestinal parasites, especially in children. These small, white worms cause itching around the anus, disturbed sleep, and irritability due to their egg-laying at night. Infection spreads via the faecal-oral route, often through ingesting microscopic eggs from contaminated hands, surfaces, or food.

Roundworms are parasitic nematodes that can infect the human digestive system, typically causing symptoms such as abdominal pain, diarrhoea, and discomfort. Transmission often occurs through contaminated soil, water, or undercooked food. If left untreated, infections can lead to more serious health complications.

Tapeworms are intestinal parasites that can affect humans and animals. These flat, segmented worms can grow to considerable lengths. They typically enter the body through the consumption of contaminated food or water. While tapeworm infections may sometimes be asymptomatic, they can also cause abdominal discomfort, diarrhoea, and weight loss.

Threadworms (Strongyloides stercoralis) are tiny intestinal parasites that cause strongyloidiasis. They may be asymptomatic or cause a range of symptoms, including abdominal pain, diarrhoea, and, in severe cases, malabsorption. Transmission takes place through skin contact with contaminated soil. These worms are notable for their ability to reproduce within the host, which can lead to persistent, long-lasting infections.

Whipworms (Trichuris trichiura) are intestinal parasites named for their distinctive whip-like shape. Infection occurs through ingestion of eggs found in soil contaminated with human faeces. While many cases present no symptoms, heavy infestations can cause diarrhoea, abdominal pain, and in severe cases, rectal prolapse. Children are particularly vulnerable, as chronic infections may affect growth and cognitive development.