Vízsfolyás

Vízsfolyás, commonly known as river blindness, is a parasitic disease caused by the filarial worm *Onchocerca volvulus*. It is primarily transmitted through the bite of infected blackflies (*Simulium* species), which are prevalent in tropical and subtropical regions of Africa, Latin America, and parts of Yemen and Angola. The parasite primarily affects the skin, eyes, and lymphatic system, leading to severe health complications.

The life cycle of *Oncherca volvulus* involves the blackfly vector. When an infected blackfly bites a human, it injects microfilariae (larval worms) into the bloodstream. These larvae mature into adult worms, which then form nodules under the skin. Over time, the female worms produce thousands of microfilariae, which migrate to various tissues, including the eyes, where they can cause irreversible blindness. Symptoms of onchocerciasis often develop years after initial infection and may include intense itching, skin rashes, and, in advanced cases, severe skin damage, hanging groin (a condition where skin hangs loosely due to fibrosis), and blindness.

Diagnosis typically involves skin snip testing, where a small sample of skin is examined under a microscope for the presence of microfilariae. Treatment primarily relies on ivermectin, a medication that kills the microfilariae but not the adult worms. In areas where loiasis (another parasitic disease) is endemic, ivermectin is not used due to the risk of severe adverse reactions. Control efforts focus on mass drug administration, vector control through insecticides, and community education to reduce blackfly populations and transmission rates.

Vízsfolyás is a significant public health concern in affected regions, particularly in rural areas where access to healthcare is limited. Efforts by organizations such as the World Health Organization (WHO) and the African Programme for Onchocerciasis Control (APOC) have led to significant reductions in disease prevalence through integrated control strategies. Prevention involves avoiding blackfly habitats, using insect repellents, and wearing protective clothing, though these measures are often challenging in endemic areas.