pathogens Article Mapping the Spatial Distribution of the Rumen Fluke Calicophoron daubneyi in a Mediterranean Area Antonio Bosco *, Martina Nocerino, Mirella Santaniello, Maria Paola Maurelli , Giuseppe Cringoli and Laura Rinaldi Department of Veterinary Medicine and Animal Production, University of Naples Federico II, CREMOPAR Campania Region, 80137 Naples, Italy; [email protected] (M.N.); [email protected] (M.S.); [email protected] (M.P.M.); [email protected] (G.C.); [email protected] (L.R.) * Correspondence: [email protected]; Tel.: +39-0812550701 Abstract: Rumen flukes (Calicophoron daubneyi) represent a growing threat to the animal health, productivity and welfare of ruminants. The present study aimed to assess the spatial distribution of C. daubneyi infections in ruminants and to develop a predictive model of the environmental suitability for rumen flukes in a Mediterranean area. A cross-sectional coprological survey was conducted in 682 sheep, 73 goat and 307 cattle farms located in the Basilicata region (southern Italy). Faecal samples collected were analysed using the FLOTAC technique. Geographical Information Systems (GIS) and statistical models were developed to determine environmental risk factors and to delimitate the areas at highest risk of infections in small ruminants. The results showed 7.9% (95% CI 6.05–10.27) of sheep farms, 2.7% (95% CI 0.48–10.44) of goat farms and 55.0% (95% CI 49.62–60.99) of cattle farms were infected by C. daubneyi. The areas with high predicted risk were situated in the western part Citation: Bosco, A.; Nocerino, M.; of the region. The soil texture, land use and the presence of streams and brooks were the variables Santaniello, M.; Maurelli, M.P.; statistically significant (p < 0.05) in explaining the C. daubneyi distribution in the study area. The Cringoli, G.; Rinaldi, L. Mapping the study confirms the importance of geospatial technology in supporting parasite control strategies in Spatial Distribution of the Rumen livestock and demonstrates that a combined use of different geostatistical techniques can improve Fluke Calicophoron daubneyi in a the prediction of the C. daubneyi infection risk in ruminants. Mediterranean Area. Pathogens 2021, 10, 1122. https://doi.org/10.3390/ Keywords: Calicophoron daubneyi; ruminant; spatial pattern; prediction; southern Italy pathogens10091122 Academic Editors: Angela Di Cesare, Donato Traversa and Simone Morelli 1. Introduction Received: 4 August 2021 Calicophoron daubneyi (rumen fluke or paramphistomes), the causative agent of param- Accepted: 28 August 2021 phistomosis, is a ubiquitous Trematoda that resides in the digestive tract of ruminants. This Published: 2 September 2021 pathogen has traditionally been considered of low clinical significance, causing a subclinical pathology, when livestock animals are maintained in their best nutritional and health status, Publisher’s Note: MDPI stays neutral as is usual in Europe [1], e.g. France [2,3] and the UK [4–6], thus representing a potential with regard to jurisdictional claims in impact on ruminant health, productivity and welfare. Heavy parasite burdens commonly published maps and institutional affil- compromise livestock production through reduced feed conversion efficiency, weight loss iations. and decreased milk yield, thus incurring economic losses with elevated morbidity and mortality [2,5]. Increased prevalence of this infection has been reported in various European coun- tries [3,7–10]. Ruminants become infected by the ingestion of encysted metacercariae on Copyright: © 2021 by the authors. pasture. The higher rate of prevalence may reflect an increased risk of infection, possibly Licensee MDPI, Basel, Switzerland. triggered by changes in climatic conditions (i.e., increased temperatures and rainfalls) This article is an open access article favoring higher transmission rates of these parasites [11]. The life cycle of C. daubneyi distributed under the terms and needs an intermediate snail host (e.g. Galba truncatula) to be completed [12] which is also conditions of the Creative Commons the predominant intermediate host of the liver fluke (Fasciola hepatica). For this reason, Attribution (CC BY) license (https:// the transmission of C. daubneyi is associated with the presence of freshwater gastropods, creativecommons.org/licenses/by/ in which the parasites multiply. The amplifying efficiency of the intra-molluscan cycle 4.0/). Pathogens 2021, 10, 1122. https://doi.org/10.3390/pathogens10091122 https://www.mdpi.com/journal/pathogens Pathogens 2021, 10, x FOR PEER REVIEW 2 of 15 Pathogens 2021, 10, 1122 predominant intermediate host of the liver fluke (Fasciola hepatica). For this reason,2 of the 15 transmission of C. daubneyi is associated with the presence of freshwater gastropods, in which the parasites multiply. The amplifying efficiency of the intra-molluscan cycle de- termines the number of metacercariae produced and the associated risk of infection in determines the number of metacercariae produced and the associated risk of infection in grazing animals [1]. grazing animals [1]. Recent studies on the spatial distribution of C. daubneyi explain the geographical het- Recent studies on the spatial distribution of C. daubneyi explain the geographical erogeneity in the probability of livestock infection due to environmental factors influenc- heterogeneity in the probability of livestock infection due to environmental factors in- ing the parasite’s life cycle [7,8,13]. However, as environmental conditions in the Mediter- fluencing the parasite’s life cycle [7,8,13]. However, as environmental conditions in the Mediterraneanranean area arearea very are varied, very varied,such as suchthe orographic/hydrographic as the orographic/hydrographic characteristics characteristics and the andcoverage the coverage of soil, ofthe soil, risk the of riskinfection of infection also varies. also varies. For this For reason, this reason, the environmental the environmental pa- parametersrameters must must be beconsidered considered in epidemiological in epidemiological studies. studies. Therefore, Therefore, geospatial geospatial health health rep- representsresents the theideal ideal approach approach for infection for infection risk detection risk detection and consequent and consequent spatial spatial distribution distri- butionmonitoring monitoring activities activities through through regular regularparasitological parasitological diagnosis. diagnosis. Compared Compared with F. hepat- with F.ica hepatica, there is, there limited is limited scientific scientific knowledg knowledgee about aboutthe spatial the spatial distribution distribution of C. daubneyi of C. daubneyi espe- especiallycially in the in Mediterranean the Mediterranean area. area.For these For thesereasons, reasons, this study this studyaimed aimedto analyse to analyse the spatial the spatialdistribution distribution of C. daubneyi of C.daubneyi infectioninfection in cattle, insheep cattle, and sheep goats andin southern goats in Italy southern in order Italy to inidentify order tothe identify main environmental the main environmental conditions conditionsfavorable for favorable the development for the development of rumen offlukes rumen and flukes their andintermediate their intermediate hosts. Thehosts. results The also results allowed also us allowed to develop us to a developpredictive a predictivemodel of the model geographical of the geographical distribution distribution of rumen flukes of rumen in small flukes ruminants in small ruminants in the study in thearea. study area. 2. Results The results showed 7.9%7.9% (95% CI 6.05–10.27) ofof sheep farms, 2.7% (95% CI 0.48–10.440.48–10.44)) of goat farms farms and and 55.0% 55.0% (95% (95% CI CI 49.62–60.99) 49.62–60.99) of ofcattle cattle farms farms infected infected by C. by daubneyiC. daubneyi. Re-. Regardinggarding the the C. daubneyiC. daubneyi eggseggs per pergram gram (EPG) (EPG) of faeces, of faeces, the mean the meanvalue valuewas 109.1 was (mini- 109.1 (minimummum = 10.0; = 10.0;maximum maximum = 1405.0) = 1405.0) in cattle in cattle farms, farms, 76.0 76.0 (min (min = =2.5; 2.5; max max = = 565.0) 565.0) in sheep farmsfarms andand 45.045.0 (min(min == 30.0; max = 60.0) 60.0) in in goat farms (Figure 11).). Figure 1.1. VariabilityVariability of ofC. C. daubneyi daubneyiegg egg counts counts in cattle,in cattle, sheep sheep and and goat goat farms: farms: mean mean (blue), (blue), maximum maxi- (grey)mum (grey) and minimum and minimum (orange) (orange) eggs per eggs gram per (EPG)gram (EPG) of faeces of faeces and standard and standard errors. errors. The densitydensity geographicalgeographical distribution of rumen flukefluke infectioninfection inin cattle,cattle, sheepsheep andand goats was calculated using KernelKernel densitydensity analysisanalysis andand mappedmapped inin FigureFigure2 2a;a; it it evidenced evidenced twotwo pronouncedpronounced spatialspatial patternspatterns atat northnorth andand atat south-westsouth-west ofof thethe studystudy area.area. The HotHot SpotSpot analysisanalysis ofof goatgoat andand sheepsheep farmsfarms revealedrevealed thatthat 6969 farmsfarms representedrepresented statistically significantsignificant hot spots at thethe 99%99% upperupper confidenceconfidence levellevel (CL(CLUU), 17 at thethe 95%95% CLU and 17 at 90 CL U.. None None of of the the farms farms represented represented statistically significantsignificant coldcold spotsspots atat thethe 99%99% CLCLUU. Instead, Instead, 1 and 38 were significantsignificant