Prevalence of gastrointestinal nematodes in winter slaughtered reindeer of northern Finland

The objective of this study was to determine the prevalence and intensity of gastrointestinal nematodes in winter-slaughtered reindeer during 2002-2004, from northern reindeer herding cooperatives in Finland. Ostertagia gruehneri of the abomasum was prevalent with low levels of infections in 100% of calves, (n = 53; mean ≈ 1300 worms per animal) and in 98% of adults, (n = 41; mean ≈ 3900 worms per animal). There was no difference in the number of O. gruehneri between male and female calves. The proportion of O. gruehneri inhibited larvae was significantly higher in calves (81%) than in adult reindeer (39%) (P = 0.005). The intestinal nematodes, Nematodirus tarandi and Nematodirella longispiculata, were detected only in reindeer calves. The numbers of these worms did not differ between male and female calves, but there was a difference in abundance between sites. High prevalence and low intensity of gastrointestinal nematodes characterized the patterns of infection of the reindeer examined in this study. It is assumed that these infections are sub-clinical and would not contribute to productivity losses.Abstract in Finnish / Lyhennelmä:Ruuansulatuskanavan sukkulamatojen esiintyminen talvella teurastetuissa pohjoissuomalaisissa poroissa Tämän työn tavoitteena oli määrittää ruuansulatuskanavan sukkulamatojen prevalenssi ja tartunnan aste talvella teurastetuissa Suomen pohjoisten paliskuntien poroissa vuosina 2002-2004. Juoksutusmahan Ostertagia gruehneri –loisella oli korkea prevalenssi, mutta infektion aste (matojen lukumäärä) oli melko matala; 100% vasoista oli infektoituneita (n = 53; keskimäärin 1300 matoa mahassa) ja 98% aikuisista (n = 41, keskimäärin 3900 matoa). Juoksutusmahamatojen määrissä ei ollut eroja naaras- ja urosvasojen välillä. Kehityksessään estyneiden (pysähtyneiden) O. gruehneri –matojen osuus oli tilastollisesti merkitsevästi korkeampi vasoilla (81%) kuin aikuisilla poroilla (39%) (P = 0.005). Suolistosukkulamatoja Nematodirus tarandi ja Nematodirella longispiculata tavattiin ainoastaan vasoilla. Näiden matojen määrä ei eronnut naaras- ja urosvasojen välillä, mutta maantieteellisiä eroja yleisyydessä havaittiin. Tutkimuksen poroille leimallinen loisten korkea prevalenssi ja matala infektioaste viittaa oireettomuuteen ja siihen, että ne ehkä eivät aiheuta tuotantotappioita. Abstract in Norwegian / Sammendrag: Prosentvis forekomst (prevalens) av rundmark (nematoder) i mage-tarm fra vinterslakta rein i nordlige Finland Studien ble gjennomført på rein (Rangifer tarandus tarandus) fra nordlige reindistrikter i Finland i perioden 2002 til 2004. Rundmarken Ostertagia gruehneri fra løpemagen var vanlig og fantes i lavt infeksjonsnivå (dvs. i relativt lite antall) i alle undersøkte kalver (100% forekomst i 53 dyr med et gjennomsnittlig antall marker per kalv på ca 1300) og i 98% av de 41 undersøkte voksne dyrene der gjennomsnittet per voksent dyr var ca 3900 marker. Andelen med hvilende (inhiberte) larver var statistisk sannsynlig høyere i kalver (81%) enn i voksen rein (39%) (P = 0.05). Tarmnematodene Nematodirus tarandi og Nematodirella longispiculata fantes bare i kalver. Her varierte prosentvis infeksjon fra 25% til 100% i flokkene. Det var ingen forskjell i intensitet (antall mark) mellom han- og hunkalver. Høy prevalens og lav intensitet var det karakteristiske infeksjonsmønsteret i denne studien. Vi antar derfor at infeksjonene er ubetydelige (er subkliniske) og at de ikke vil bidra til produksjonstap

Nematode parasites of reindeer in Fennoscandia

Nematode infections of semi-domesticated reindeer of northern Finland were monitored by faecal egg counts. The tracer calf technique was also used to estimate the acquisition of nematode infection from pasture. The most abundant parasite in the worm counts of tracer animals and in faecal egg counts of adult female reindeer was Ostertagia gruehneri. Capillaria sp. eggs were detected in calves and adults, but Nematodirinae eggs were only recovered from calves. Egg output of O. gruehneri was most abundant from late summer to autumn whereas Capillaria sp. and the Nematodirinae dominated the winter months. The proportion of inhibited larvae of O. gruehneri and Nematodirinae steadily increased from summer to early winter, followed by a decline and a commensurate increase in the number of adult parasites in the second summer. High prevalence and low intensity also characterized the nematode infections of winter-slaughtered reindeer from other northern herds examined. Our investigations showed that parasite transmission occurs throughout the year in this part of the sub-Arctic. We demonstrated that reindeer are suitable hosts for important nematode parasites of sheep and goats (Haemonchus contortus and Teladorsagia circumcincta) and cattle (Ostertagia ostertagi), as well as for Trichostrongylus axei. However, it is not known if all of these parasite species reach maturity in reindeer. With the trend towards increasing numbers of livestock in the southern grazing regions of reindeer, these findings highlight the increased risks with parasites not normally associated with reindeer. Approximately 80% of reindeer in Finland are de-wormed with ivermectin once annually in the winter. We analysed soil samples containing faeces from reindeer treated with ivermectin. Ivermectin degraded rapidly during the first spring, but residual levels were detected for more than two summer seasons following treatment. Residues were similar from ungrazed and grazed reindeer pastures, but the levels in faeces from reindeer treated with oral ivermectin were higher than for the subcutaneous formulation. Our results show that ivermectin persists on pasture longer than previously shown. However, the levels found had no detectable negative effects on the soil nematode communities beneath the faeces