Skin infection by parasitic scabies mites is one of the most common dermatological conditions globally, resulting in considerable morbidity, disability, stigma and exacerbation of poverty. Tropical regions, including Fiji, are particularly affected. The initial mite infection causing the alteration of the skin barrier often leads to secondary infections with opportunistic bacteria. Group A streptococcus (GAS) is a common pathogen associated with scabies in the tropics. Notably, these infections can cause severe post-infective complications, such as post-streptococcal glomerulonephritis, acute rheumatic fever and rheumatic heart disease. Our recent research revealed a fascinating synergy between parasite, associated opportunistic pathogens and their human host. Two projects will be discussed:
Investigating the tripartite interactions between host, parasite and microbial pathogens could serve as a basis to develop novel intervention strategies targeting both, mites and bacteria. We proposed that scabies mites play a role in the establishment, proliferation and transmission of GAS. Scabies mites secrete several classes of complement inhibiting proteins into the mite gut and excrete them into the epidermal mite burrows. These inhibitors promoted the growth various GAS clinical isolates in whole blood bactericidal assays and reduced the opsonisation of the bacteria surface as well as the phagocytosis of bacteria by neutrophils.
We commenced scabies microbiome studies to elucidate the impact of scabies on the healthy skin microbiota and to identify the pathogenic and symbiotic bacteria carried by scabies mites. Shotgun metagenomic and amplicon-based approaches are underway to understand the microbiomes associated with scabies mites in patients from Northern Australia, India, France and Mexico.