Diversity of Trichobilharzia in New Zealand with a new species and a redescription, and their likely contribution to cercarial dermatitis

Abstract

In response to annual outbreaks of human cercarial dermatitis (HCD) in Lake Wanaka, New Zealand, ducks and snails were collected and screened for avian schistosomes. During the survey from 2009 to 2017, four species of Trichobilharzia were recovered. Specimens were examined both morphologically and genetically. Trichobilharzia querquedulae, a species known from four continents, was found in the visceral veins of the duck Spatula rhynchotis but the snail host remains unknown. Cercaria longicauda [i.e. Trichobilharzia longicauda (Macfarlane, 1944) Davis, 2006], considered the major aetiological agent of HCD in Lake Wanaka, was discovered, and redescribed from adults in the visceral veins of the duck Aythya novaeseelandiae and cercariae from the snail Austropeplea tomentosa. Recovered from the nasal mucosa of Ay. novaeseelandiae is a new species of Trichobilharzia that was also found to cycle naturally through Au. tomentosa. Cercariae of a fourth species of Trichobilharzia were found in Au. tomentosa but the species remains unidentified.

Simplifying Schistosome Surveillance: Using Molecular Cercariometry to Detect and Quantify Cercariae in Water

“…Species of Trichobilharzia constitute the majority of the avian schistosomes [ 59 , 60 ] and are an excellent model system for human schistosomes. Avian schistosomes have been under investigation in Michigan since 1928, where their ability to cause swimmer’s itch was confirmed [ 61 , 62 ].…”

Systematics and life cycles of four avian schistosomatids from Southern Cone of South America

“…Therefore, based on the known data, with published sequences and vouchers from the blue-winged ducks (Spatula spp.) clade such as S. versicolor from Argentina (Ebbs et al, 2016), S. discors and S. cyanoptera from the USA (Brant & Loker, 2009;Garvon et al, 2011), and the Australian shoveler [Spatula rhynchotis (Latham)] from New Zealand (Davis et al, 2022), they are most likely T. querquedulae. Interestingly, previous records from other species of Spatula from the USA (Brant & Loker, 2009), and the recent proposal by Ebbs et al (2016), stated that T. querquedulae has a cosmopolitan distribution in Spatula spp.…”

“…Genetically the specimens of T. querquedulae isolated in S. cyanoptera grouped with those from Brant & Loker (2009) and Davis et al . (2022). Morphologically, the specimens were mostly similar to the descriptions of Brant & Loker (2009) and McLeod (1937) but there were subtle differences.…”

“…The specimens found here represent the first records from Chile, widening its known geographic distribution in the Southern Cone, plus representing the second record and an additional host species in the Neotropics. The high prevalence of T. querquedulae in S. cyanoptera (6/6) and intensity of infection ( M A = 68.83) are remarkable similar to what has been reported previously (Brant & Loker, 2009; Davis et al ., 2022).…”

Scratching the Itch: Updated Perspectives on the Schistosomes Responsible for Swimmer’s Itch around the World

“…The schistosomes and hosts involved fit a familiar pattern (see T. stagnicolae in Figure 1 ), with the adult worms found in visceral veins of waterfowl, eggs passed in the feces, and snails of the family Lymnaeidae serving as intermediate hosts. Prominent examples are T. stagnicolae in North America [ 55 , 56 , 57 , 58 , 59 , 60 , 61 ], T. szidati and T. franki in Europe [ 17 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 ], and a species long known from cercariae and swimmer’s itch outbreaks but only recently described from adult specimens and named T. longicauda in New Zealand [ 71 ]. The snails involved tend to be associated with higher latitudes and are relatively large, which may lead to high cercariae production and, therefore, increased likelihood of being involved in swimmer’s itch cases.…”