Evolution and Otitis Media: A Review, and a Model to Explain High Prevalence in Indigenous Populations

Abstract

Inflammation of the middle ear (otitis media) comprises a group of disorders that are highly prevalent in childhood, and indeed are amongst the most common disorders of childhood. Otitis media is also heritable, and has effects on fecundity. This means that otitis media is subject to evolution, yet the evolutionary selection forces that may determine susceptibility to otitis media have never been adequately explored.Here I undertake a critical analysis of evolutionary forces that may determine susceptibility to middle ear inflammation. These forces include those determining function of the middle ear, those affecting host immunity, and those affecting colonization by, and pathogenicity of bacteria. I review existing mathematical evolutionary models of host-pathogen interaction and co-evolution, and apply these to develop a better understanding of the complex evolutionary landscape of middle ear infection and inflammation in humans. This includes an understanding of factors Pre--print version. Visit http://digitalcommons.wayne.edu/humbiol/ after 1 October 2015 to acquire the final version.2 determining the transition between stable evolutionary strategies for host and bacterial pathogens. This understanding will be later applied to analysis of otitis media in indigenous populations.In the second part of this article, I apply the approach of population genetics to devise a new theory for the high prevalence of otitis media in certain indigenous populations: the Australian Aborigine, the Native American, the Inuit, and the Maori.I suggest that high prevalence in such groups may have occurred as a result of colonization of these previously isolated populations by European immigrants in the 15 th and 16 th Centuries. This exposed them to new strains of bacteria to which their immune system had not evolved immunity, perturbing a previously stable hostpathogen co-evolutionary state.

Global burden of hearing impairment and ear disease

“…26 Indigenous populations may be at greater risk of developing otitis media because of factors related to colonisation, including exposure to high population density pathogens since colonisation, and the influence of socioeconomic conditions (which drive infection), particularly in remote areas. 27 In other indigenous populations, there has been a trend towards decreased otitis media. Amongst Arctic Circle Inuit school children, otitis media prevalence decreased from 30-50 per cent in the 1960s to around 10 per cent in the 1990s.…”

Australian Aboriginal Children with Otitis Media Have Reduced Antibody Titers to Specific Nontypeable Haemophilus influenzae Vaccine Antigens

“…While 10 to 20% of nonindigenous children develop chronic or recurrent OM, the condition is almost universal among Australian Aboriginal children by 12 months of age and persists to school age (4–6). OM is also endemic in other indigenous populations, such as Native American, Greenlandic and Alaskan Inuit, and Maori populations (7); however, the rates of OM reported for Australian Aboriginal children are the highest in the world (8). …”

Genomics of Otitis Media (OM): Molecular Genetics Approaches to Characterize Disease Pathophysiology

“…The genetic contribution to OM susceptibility became evident in the 1980s after several studies showed that the prevalence of OM was disproportionately high in some ethnicities (native Americans and Australian aborigines) and relatively low in individuals of African ancestry (Clements, 1968;Bhutta, 2015). A surveillance study on ear and nasopharyngeal carriage was conducted among remote Australian aboriginal communities in 2013 and found that 50% of young children (mean age 13 months) had OME, 37% had AOM, and 12% had CSOM (Leach et al, 2016).…”