Distribution of rickettsioses in Oceania: Past patterns and implications for the future

Abstract

Rickettsioses present a threat to human health worldwide, but relatively little is known on their epidemiology and ecology in Oceania. These bacteria are the cause of potentially fatal febrile illnesses in humans (categorized into scrub typhus, typhus group and spotted fever group rickettsioses). They are transmitted by arthropod vectors such as ticks, mites, fleas and lice, which are associated with vertebrate host animals including rodents and companion animals. We conducted a search in the scientific and grey literature of Rickettsia spp. and Orientia tsutsugamushi within the Oceania region. Human case reports, human serosurveys and PCR-based testing of vectors and host animals reviewed here highlight the widespread distribution of these pathogens in the region, with the majority of human serological and vector surveys reporting positive results. These findings suggest that rickettsioses may have a significantly higher burden of disease in Oceania than is currently appreciated due to diagnostic challenges. Furthermore, consideration of the ecology and risk factors for rickettsioses reported for Oceania suggests that their importance as a cause of undifferentiated acute febrile illness may grow in the future: environmental and social changes driven by predicted climate change and population growth have the potential to lead to the emergence of rickettsioses as a significant public health problem in Oceania.

Murine models of scrub typhus associated with host control of Orientia tsutsugamushi infection

“…Individuals are infected with the bacteria transmitted to humans during feeding by infected larval trombiculid mites. Foci of transmission correspond to the distribution of the chigger mite vectors whose habitat consists of secondary or transitional forms of vegetation that exist after environmental modification such as removal of primary forests, practice of shifting cultivation, abandonment of fields, plantations and village sites during conflict, and neglect of urban and suburban garden plots [11,12,13,14]. The prospect of increasing vector habitat and the wide geographic distribution stress the importance and widespread impact of this disease, emphasizing the need for an effective vaccine.…”

Absence of serological evidence of Rickettsia spp., Bartonella spp., Ehrlichia spp. and Coxiella burnetii infections in American Samoa

“…in Oceania, and 96 discussed their potential for emergence as a result of the impacts of climate change, 97 population growth, and urbanisation on disease ecology (Derne et al, 2015). Despite the high 98 frequency of contact with domestic pets and specific reports of flea and tick bites in our study 99 population, Rickettsia spp., Bartonella spp., Ehrlichia spp.…”

Réservoirs et vecteurs de bartonelles et de rickettsies en Nouvelle-Calédonie

“…Rickettsia felis est considéré comme étant l'agent du groupe boutonneux le plus répandu en Océanie, ce qui reflète la distribution mondiale de ce pathogène émergent pour l'Homme (Derne et al 2015). Il a également été détecté dans les îles Samoa américaines (Tuten et al 2013).…”