Epidemiological investigation of a severe rumen fluke outbreak on an Irish dairy farm

Abstract

Although the rumen fluke, Calicophoron daubneyi is now very common and widespread throughout Western Europe, reports of clinical cases are still rare. This study explores the epidemiological background to a severe rumen fluke outbreak in 6-month-old heifers on a dairy farm in Ireland. Sequence analysis of the cytochrome oxidase subunit 1 (Cox1) gene of the rumen fluke metacercariae on pasture failed to identify predominant, possibly pathogenic subtypes. However, estimates of metacercarial load indicated that the animals were exposed to a daily dose of about 5334 C. daubneyi metacercariae for a period of 3 weeks resulting in the build-up of very large numbers of immature worms in the small intestine. It is hypothesized that specific environmental conditions may favour this parasite over its competitor, the liver fluke, Fasciola hepatica, possibly by allowing it to emerge earlier. The possibility that C. daubneyi may be better adapted to the Irish climate than F. hepatica together with the fact that selective treatment against F. hepatica effectively frees the niche for C. daubneyi, may result in the gradual replacement of F. hepatica by C. daubneyi.

Calicophoron daubneyi—The Path Toward Understanding Its Pathogenicity and Host Interactions

“…It has also been suggested that C. daubneyi is adapting to out-compete the already endemic F. hepatica in their shared environment and snail intermediate host species ( 7 ). Furthermore, the widespread use of fasciolicides, to target liver fluke—most but not all are specific for liver fluke—may be giving C. daubneyi further competitive advantage over F. hepatica , such that C. daubneyi may eventually replace F. hepatica as the most prevalent endemic trematode in the UK/Ireland ( 8 ).…”

“…Whilst paramphistomes are common in the UK/Ireland, clinical disease (i.e., poor condition/emaciation, with or without death, associated with acute infection) as described by Millar et al ( 12 ) and Mason et al ( 15 ) is still relatively rare. However, fatal disease outbreaks, linked to significant immature parasite burdens, are on the rise in both sheep and cattle ( 8 , 11 , 12 , 15 ). For example, in a particularly severe outbreak on an Irish farm, 6-months old dairy heifers ingested an estimated 5,334 metacercariae each day over 3 weeks ( 8 ).…”

“…However, fatal disease outbreaks, linked to significant immature parasite burdens, are on the rise in both sheep and cattle ( 8 , 11 , 12 , 15 ). For example, in a particularly severe outbreak on an Irish farm, 6-months old dairy heifers ingested an estimated 5,334 metacercariae each day over 3 weeks ( 8 ). Indeed, the Disease Surveillance and Investigation Branch of the Agri-food and Biosciences Institute (Northern Ireland) are seeing an increasing number of sudden deaths that showed no clinical presentation other than acute rumen fluke infection at post-mortem examination—particularly during years with mild wet conditions during the spring and early summer (Prof. Bob Hanna, personal communication, 2019).…”

Paramphistomidose – eine Übersicht zu Epidemiologie und klinischer Symptomatik

“…Intestinale Paramphistomidose führt bei Massenbefall zu ernsthaften Erkrankungen, wobei keine spezifische Symptomatik vorliegt [5][8] [44]. Vorberichtlicher Weidegang auf stark vernässten Böden ist für akute Ausbrüche pathognomonisch [47]. Obwohl die jährliche Inzidenz für intestinale Paramphistomidose bisher unter 5 % liegt [72], sollte bei Weidetieren mit akutem Durchfallgeschehen differenzialdiagnostisch auch an den Nachweis von Jungegeln im Kot gedacht werden [9] [12].…”

Transcriptome and Secretome Analysis of Intra-Mammalian Life-Stages of Calicophoron daubneyi Reveals Adaptation to a Unique Host Environment

“…Acute, clinical paramphistomosis is caused when grazing stock ingest large numbers of metacercariae from pasture, which then excyst en masse in the duodenum (4). The newly excysted juvenile (NEJ) flukes then migrate into the intestinal submucosa causing significant damage to the host tissue (5).…”