The Galapagos sea lion (Zalophus wollebaeki) is an endemic and endangered species that plays a vital role in the ecosystem dynamics of the archipelago. In recent decades, they have faced a significant population decline, related to the effects of climate variability and anthropogenic influences. Thus, the co-occurrence of sea lion resting areas with mosquito breeding sites and the presence of free-roaming domestic dogs present significant health risks related to parasite transmission. This research demonstrates the occurrence of Dirofilaria immitis (canine heartworm) in Z. wollebaeki, indicating their possible function as a definitive host for this parasite. Blood samples collected in August 2023 from 50 individuals (juveniles and adults) in 2 rookeries of San Cristóbal Island, revealed a 2% prevalence of D. immitis in juvenile females, as confirmed by Knott’s test and polymerase chain reaction analysis. Results of this work emphasize the critical necessity for effective monitoring and conservation strategies to address the threat posed by D. immitis and to safeguard this endangered species.

Culicoides vectors can transmit a diverse array of parasites and are globally distributed. We studied feeding preferences and seasonal variation of Culicoides (Diptera: Ceratopogonidae) vectors in an urban forest of Germany to determine whether humans living nearby are readily exposed to vector-borne parasites from wild animals. We used a fragment of the mtDNA COI gene to identify hosts from blood meals. We amplified a fragment of the mtDNA cyt b to detect haemosporidian infections in Culicoides abdomens and thoraxes. We detected a total of 22 Culicoides species. Fifty-eight blood meals (84%) were from humans, 10 from birds, and one from livestock. We found Culicoides kibunensis (considered ornithophilic) with 29 human blood meals. Host generalist Culicoides festivipennis and Culicoides obsoletus had 14 human blood meals. Culicoides clastrieri and Culicoides semimaculatus fed on birds; previously humans were their only known host. Six thoraxes and three abdomens were infected with either Haemoproteus pallidulus or Haemoproteus parabelopolskyi. There were changes in Culicoides community structure across months. Culicoides pictipennis was the dominant species during spring, C. kibunensis and C. clastrieri were dominant during summer, and C. obsoletus was dominant by early autumn. All dominant species were generalists feeding on birds, livestock and humans. Our results indicate that humans can serve as a blood source for dominant Culicoides species instead of the normal wild animal hosts in urban areas.