Spring is upon us and, as every year, also the problem of external parasites which, besides being annoying, are dangerous for animals and humans.

The table lists the parasites and pathologies that they may be responsible for: The battle against these parasites, and thus the problems which they cause, is fought through prevention in these months, when the hot/humid weather promotes the recovery of the biological cycle interrupted by the winter cold. The most known and most used products are certainly those whose active ingredients are Fipronil, Methoprene, Imidacloprid and Permethrin, which first affect the nervous system of the parasite, leading to paralysis, so with a great adulticide action, or as growth inhibitors, acting in various phases of the life cycle from egg to adult insect. Many of the products on the market combine the two molecules, exploiting both actions to prolong the effectiveness of the product itself and to avoid resistance phenomena which, unfortunately, are frequent. These molecules, however, have a certain toxicity, both for man and for animals, so they must be administered with great care (permethrin, for example, is toxic to cats and causes their death). Today the market is enriched with new products with antiparasitic action, the ingredients of which, however, are of natural origin. The Pyrethrins, a class of natural molecules already known for some time for their antiparasitic activity, are extracted from the Chrysanthemum cineraefolium, whose flower heads, dried and pulverized, produce Pyrethrum powder, hence the name. Their parasiticide activity, of short duration for the low toxicity, is carried out by contact and / or ingestion, by acting on the nervous system and leading to paralysis. In addition, on contact with air and light the Pyrethrins degrade, for which reason on the market are only found semisynthetic or synthetic derivatives, pyrethroids, not devoid of toxicity to humans. Current and important substance is Neem oil, a substance with an antiparasitic action present in new formulations. Neem oil comes from a tree, the "Azadirachta indica", of Indian origin and known as "the tree that alleviates disease" as it has anti-inflammatory, antipyretic, analgesic, antifungal and antiparasitic properties. In the 60s, in Sudan, some scholars witnessed an attack of locusts, which ate the leaves of all the trees of various plantations without damaging any of the Neem tree leaves. From this observation they began studies and discovered a good repellent and antiparasitic activity on about 200 insects. Farmers in Central America use as repellents in their crops a solution obtained by maceration for 20 days of the crushed seeds.

Antiparasitic action of the Neem is expressed:

• as an insecticide, altering the reproductive and metabolic capacities of the adult;
• as a IGR (insect growth regulator), blocking the metamorphosis in the various stages of the life cycle of insects;
• as a repellent, for the presence of salannina.

Studies show that the Neem, although toxic to certain types of insect, is not toxic for warm-blooded animals and is therefore harmless both for men and for their pets. In the US, for years there have been registered for humans spray products acting as repellents against fleas, ticks, mosquitoes, or shampoo for children's lice. In Italy in recent years anti-lice shampoos are available. In veterinary medicine there are new products based on Neem Oil, which have a high efficacy both as an insecticide and as a repellent for fleas, ticks, mosquitoes and sand flies and are not toxic either for animals or for humans.