Every cockroach is beautiful to its mother.

cockroaches is not easy to document, given the precarious hygienic conditions of some of the habitats where they live. In fact, asthma is the only disease consistently associated with exposure to cockroaches [4–6] . Curiously enough, cockroaches have no lungs (they breathe through lateral spiracles in the body) [1] , but inhalation of cockroach materials by humans may trigger IgE antibody responses, lung eosinophilic inflammation and asthma attacks. The first reports on exposure to cockroach and IgE sensitization were published in the early 1960s [7, 8] . Subsequent studies have established an important role of exposure and sensitization to cockroach in causing earlier onset and more severe symptoms of asthma, particularly among inner-city and underprivileged populations, at lower doses of allergen as compared to other allergen sources [9] . How do people become sensitized to cockroaches? Where do cockroach allergens come from? What is special about cockroach allergens? Those are very important questions. In the past 20 years, advances in understanding cockroach allergy have been possible through the identification, characterization, molecular cloning and recombinant expression of cockroach allergens [4, 5] . In addition, development of assays for measuring cockroach allergens (Bla g 1 and Bla g 2 in particular) has been fundamental to establish the importance of environmental exposure to cockroach in asthma [10] . Cockroach debris, secretions and cast-overs are thought to be important sources of allergens [6] . Allergen Cockroaches are considered to be among the oldest insects on our planet, predating dinosaurs by more than 150 million years and humans by more than 300 million [1] . Some fossils attributed to cockroaches date back to the Carboniferous period, around 325 million BC. However, an uncertain evolutionary link between cockroachlike fossils from the Carboniferous period (Paleozoic era) and ‘modern’ cockroaches, which originated in the Cretaceous period (Mesozoic era) as did most other insects, has also been suggested, due to morphological differences [2] . Regardless of their origin, cockroaches have undergone very few changes over time, and the diversification of species and adaptation to multiple habitats are remarkable, reflecting their tremendous success at surviving throughout evolution [1] . Over 4,000 cockroach species have been identified, with tropical forests as their preferred habitat [3] . However, a few species, including the German cockroach (Blattella germanica) and the American cockroach (Periplaneta americana) , brought from Africa to the Americas on slave ships, have adapted to live near people, turning into household pests. The Neapolitan folk saying Ogni scarrafone è bello a mamma sua (Every cockroach is beautiful to its mother) may soften the disgust towards the cockroach. Among the general population, there is strong concern that cockroaches can serve as vectors of diseases, representing a threat to human health. Although cockroaches may harbor bacteria, viruses, fungi and parasites, dissemination of diseases by Published online: May 14, 2013