Lack of hygiene and lack of caution sometimes lead to vacation souvenirs of a special kind: worm diseases. Particularly dangerous are worm diseases that can be contracted when traveling to tropical countries.
Loa loa – this sounds like a tasty tropical fruit, but it is actually a tiny worm from the nematode family. These thin, twig-like worms are also called filariae, which prefer to colonize the lymphatic system of humans, causing severe clinical pictures.
Filariae include parasites such as Loa Loa, the Guinea worm, and Onchocerca volvulus, the causative agent of river blindness. Of greatest medical relevance are the flatworms from the class of trematodes – flukes – also called schistosomes, which transmit the dangerous schistosomiasis.
Threadworms lurk everywhere
In Central and West Africa, biting mangrove flies transmit Loa Loa larvae. These grow in the lymphatic system of humans; the adult, female worms migrate around in the connective tissue of the skin and mucous membranes, produce eggs, which in turn circulate in blood vessels and form larvae – the microfilariae. If the human is bitten again, the insects ingest the larvae and pass them on during the next blood meal.
According to the WHO, about 13 million people are infected with Loa Loa. Diagnosis is made by antibody detection in the blood, or by detection of the microfilariae in the blood. The only effective protection is an effective insect repellent for the skin or mosquito nets. The worms are sometimes surgically removed, but mainly they are treated with strong drugs (diethycarbamazine) that have to be taken for a long time. This causes the parasites to die, and there may be a mass release of antigens, leading to severe allergic reactions.
Danger: river blindness
Nematodes are found almost everywhere in the world: on beaches, in the ocean, even in farmland. Certain species can even nest in people’s eyes and cause river blindness – onchocerciasis – which is feared in the tropics. The nematodes settle in the subcutaneous tissue of humans and form nodules, known as onchocercomas, in the skin. The female parasites produce about five to ten million offspring during their lifetime. These larvae can spread throughout the human body and also enter the eye, where they cause visual impairment and even blindness.
The disease is transmitted by the bite of black flies, which can only develop in flowing, oxygen-rich waters. In tropical countries, hygienic conditions are not always good, so you should only drink bottled mineral water or boiled water, avoid fresh fruit and vegetable juices, and always peel fruit. The same applies to salad or meat.
According to the Bremen Mitte Clinic, treatment of river blindness should be started very slowly, because rapid destruction of the parasites places an enormous burden on the patient’s body. First, existing skin nodes are surgically removed. This is especially true for nodes on the head to avoid damage to the eyes. This is followed by special chemotherapy, which destroys the worms and their offspring.
