Paraziti

Paraziti are organisms that live in or on another organism, the host, from which they derive benefits at the host's expense. They can be microscopic, such as protozoa, or multicellular, such as helminths and ectoparasites. Parasites may be obligate, requiring a host to complete their life cycle, or facultative, able to inhabit a host only occasionally.

Major groups include protozoa (for example Plasmodium, Giardia, Entamoeba), helminths (trematodes, cestodes, nematodes such as Schistosoma, Taenia, Ascaris), and ectoparasites (lice, fleas, mites, ticks). Some parasites have complex life cycles with intermediate hosts or vectors, while others infect directly.

Transmission occurs via ingestion of contaminated food or water, contact with contaminated soil or surfaces, skin penetration, or bites from vectors such as mosquitoes or ticks. Parasitic infections can be acute or chronic and may impact nutrition, growth, immunity, and organ function.

Examples of diseases include malaria (Plasmodium), giardiasis (Giardia), amoebiasis (Entamoeba histolytica), toxoplasmosis (Toxoplasma gondii), schistosomiasis (Schistosoma), and helminth infections such as roundworm, tapeworm, and hookworm.

Diagnosis relies on microscopy, molecular tests, serology, or antigen detection. Treatment depends on the parasite and includes antiparasitic drugs such as metronidazole, albendazole, praziquantel, ivermectin, or combination therapy. Prevention focuses on sanitation, clean drinking water, food safety, vector control, and personal protective measures.