PhD Student
Justus-Liebig-Universität Gießen

Abstract

Consisting of five different genera, the family Echinophthiriidae belongs to phthirapteran suborder Anoplura, which represents a group of permanent, obligate, and wing-free ectoparasitic insects of eutherian mammals. Members of this unique family were reported to exclusively parasitize mammals with a semiaquatic lifestyle, such as Pinnipedia (seals, sea lions and walruses) and the North American river otter (Lontra canadensis).

In the framework of my PhD thesis, an “urban” bachelor group of South American sea lions (Otaria flavescens) living in the southern Chilean city Valdivia in a freshwater biotope was examined regarding their ectoparasite fauna. For first time, we describe a novel non-invasive method applied in parasitological research for marine mammals: a lice comb, screwed on a telescopic rod was used for epidermis material collection (fur coat hair, lice, nits and skin tissue samples) from living animals. During sample-taking process, the echinophthiriid species Antarctophthirus microchir was detected in 4/5 individuals, exclusively at the junction between the back and hind flippers. Our findings constitute the first report of A. microchir infestation in this unique synanthropic colony of South American sea lions from Valdivia, Chile. Findings of different life stages proof complete life cycle of A. microchir, despite inhabiting a freshwater habitat and in absence of females or pups. The “telescopic lice comb” enables completely new possibilities to collect different kind of epidermis material, such as fur coat hair, lice, nits and skin tissue samples, for a wide spectrum of possible research fields.

Another echinophtiriid species Echinophthirius horridus, the seal louse, has been reported to parasitize a broad range of representatives of phocid seals, including harbor seals (Phoca vitulina) and grey seals (Halichoerus grypus). In the past, many studies examined the morphology and biology of echinophthiriid lice but only few studies focused on vector function and knowledge on their role in pathogen transmission is still scarce. Therefore, we aimed to investigate the potential role of E. horridus in vector-borne diseases of seals in the Dutch Wadden Sea and to attribute to its morphological features of environmental adaptation. Seal lice from 35% of the harbour seals (19/54) and from one grey seal proved positive for Acanthocheilonema spirocauda, the seal heartworm. Anaplasma phagocytophilum and a Mycoplasma species previously identified from a patient with disseminated ‘seal finger’ mycoplasmosis were detected the first time in seal lice. SEM analyses of E. horridus-adults and -eggs brought out more clearly unique morphological features, such as ‘lock-like’ claws, setae-covered cuticle as well as vaulted nit lids carrying micropyles for respiration, which all demonstrate the adaption of this ectoparasite to its semiaquatic host and the marine environment.