Diagnosis of Liver Fluke Infection in Cattle
Diagnosis of Liver Fluke Infection in Cattle - Merial
Diagnosis of Liver Fluke Infection in Cattle - Merial
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<strong>Diagnosis</strong> <strong>of</strong> <strong>Liver</strong> <strong>Fluke</strong> <strong>Infection</strong> <strong>in</strong> <strong>Cattle</strong> Page 1 <strong>of</strong> 4<br />
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<strong>Diagnosis</strong> <strong>of</strong> <strong>Liver</strong> <strong>Fluke</strong> <strong>Infection</strong> <strong>in</strong> <strong>Cattle</strong><br />
Donald W. Briskey DVM<br />
A Diagnostic Review<br />
Economic Impact<br />
<strong>of</strong> <strong>Fluke</strong><br />
Infestation <strong>in</strong><br />
Kansas Feedlots<br />
J. R. Brown<br />
Merial Veter<strong>in</strong>ary<br />
Bullet<strong>in</strong><br />
TSB-0-00019-FTB<br />
Economic<br />
Importance <strong>of</strong><br />
<strong>Liver</strong> <strong>Fluke</strong>s and<br />
<strong>Fluke</strong> Control <strong>in</strong><br />
<strong>Cattle</strong> From the<br />
Gulf Coast<br />
Region<br />
D. Gerdon<br />
Merial Veter<strong>in</strong>ary<br />
Bullet<strong>in</strong><br />
TSB-0-0029-FTB<br />
The Parasite<br />
Fasciola hepatica, the common liver fluke, is the most likely cause <strong>of</strong> liver<br />
fluke disease <strong>in</strong> domestic rum<strong>in</strong>ants <strong>in</strong> the United States. The fluke life<br />
cycle requires a snail <strong>in</strong>termediate host to complete transmission to a new<br />
rum<strong>in</strong>ant host. The parasite is most <strong>of</strong>ten found <strong>in</strong> Florida, along the Gulf<br />
Coast, <strong>in</strong> the Pacific Northwest, <strong>in</strong> portions <strong>of</strong> the Rocky Mounta<strong>in</strong>s, and<br />
Hawaii. Other areas, such as Oklahoma, Nebraska and Kansas, have<br />
reported local cattle with fluke disease. This suggests liver flukes are<br />
expand<strong>in</strong>g their range.<br />
TSB-8-98018-<br />
FTB<br />
(formerly TSB-4-<br />
94016-FTB)<br />
®IVOMEC and<br />
CURATREM are<br />
registered<br />
trademarks <strong>of</strong><br />
Merial.<br />
<strong>Diagnosis</strong> - Exam<strong>in</strong>ation <strong>of</strong> the <strong>Liver</strong><br />
<strong>Diagnosis</strong> <strong>of</strong> liver flukes <strong>in</strong> cattle is a challenge. The most direct technique<br />
is liver exam<strong>in</strong>ation at slaughter or necropsy. While this method can<br />
provide <strong>in</strong>formation about the status <strong>of</strong> liver flukes on a particular property,<br />
it does not evaluate annual variations <strong>of</strong> <strong>in</strong>fection level or lend itself to use<br />
with arriv<strong>in</strong>g feedlot cattle from unknown orig<strong>in</strong>s.<br />
<strong>Diagnosis</strong><br />
Fecal Exam<br />
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<strong>Diagnosis</strong> <strong>of</strong> <strong>Liver</strong> <strong>Fluke</strong> <strong>Infection</strong> <strong>in</strong> <strong>Cattle</strong> Page 2 <strong>of</strong> 4<br />
®FLUKEFINDER<br />
is a registered<br />
trademark <strong>of</strong><br />
Visual Difference.<br />
© 1998 Merial<br />
Limited. All rights<br />
reserved.<br />
<strong>Diagnosis</strong> - Fecal Exam<br />
Another diagnostic procedure is fecal exam<strong>in</strong>ation for F. hepatica eggs.<br />
Two po<strong>in</strong>ts need to be kept <strong>in</strong> m<strong>in</strong>d when <strong>in</strong>terpret<strong>in</strong>g fecal exam results for<br />
F. hepatica:<br />
a) The prepatent period for F. hepatica is 2-3 months. As a<br />
result, fluke eggs cannot be demonstrated early <strong>in</strong> the <strong>in</strong>fection.<br />
A group <strong>of</strong> cattle could be carry<strong>in</strong>g a high burden <strong>of</strong> young<br />
flukes, but no fluke eggs would show up <strong>in</strong> their manure.<br />
b) The quantitative value <strong>of</strong> fluke egg counts is questionable.<br />
<strong>Fluke</strong> eggs pool <strong>in</strong> the gallbladder and <strong>in</strong>termittently pass <strong>in</strong>to<br />
the feces.(1) The fluke egg count on any given day <strong>of</strong>ten has<br />
little relationship to the number <strong>of</strong> flukes <strong>in</strong> the liver. An<br />
animal with a negative fecal could be parasitized, whereas a<br />
high fecal fluke egg count could just be a high number <strong>of</strong> eggs<br />
leav<strong>in</strong>g the gallbladder that day, rather than a large fluke<br />
burden.<br />
Fecal Exam<strong>in</strong>ation Techniques<br />
Fecal exam<strong>in</strong>ation for fluke eggs requires use <strong>of</strong> fecal sedimentation,<br />
formal<strong>in</strong>-ether, or FLUKEFINDER® techniques. Commonly used flotation<br />
procedures open the operculum and s<strong>in</strong>k the fluke egg rather than float<strong>in</strong>g it<br />
for surface detection.(2,3) The FLUKEFINDER screen system has the<br />
advantages <strong>of</strong> be<strong>in</strong>g faster and simpler than other techniques and it requires<br />
no chemicals. The FLUKEFINDER may also be used <strong>in</strong> the field for<br />
evaluation <strong>of</strong> arriv<strong>in</strong>g cattle.(4) In monitor<strong>in</strong>g liver fluke <strong>in</strong>fections, it is<br />
critical to remember that the fecal exam techniques most frequently used<br />
for nematodes will not demonstrate fluke eggs.<br />
<strong>Fluke</strong> Egg Seasonality<br />
Seasonality <strong>of</strong> new liver fluke <strong>in</strong>fections also affects the time <strong>of</strong> year that<br />
fecal exams can be expected to show fluke eggs. In an Idaho study, calves<br />
picked up an <strong>in</strong>creas<strong>in</strong>g number <strong>of</strong> flukes as the pasture season progressed.<br />
Transmission peaked <strong>in</strong> November.(5) With the 2-3 month prepatent<br />
period, the majority <strong>of</strong> fecals wouldn't be positive until December or later.<br />
Fecal exams for flukes at the typical process<strong>in</strong>g time <strong>of</strong> October would miss<br />
immature fluke <strong>in</strong>fections <strong>in</strong> Northwest calves.<br />
In Louisiana, the Gulf Coast transmission pattern for flukes has been<br />
demonstrated to be primarily February-July.(6) Allow<strong>in</strong>g for the prepatent<br />
period, fecals start to show positive for fluke eggs 2-3 months after the peak<br />
transmission times.<br />
Disease Signs<br />
The signs caused by liver flukes <strong>in</strong> cattle range over the follow<strong>in</strong>g<br />
syndromes:<br />
a) chronic disease with anemia, bottle jaw and overall<br />
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unthrift<strong>in</strong>ess.<br />
b) subacute disease with anemia, hemorrhage and death <strong>in</strong> 7-10<br />
weeks.<br />
c) acute death.<br />
d) subcl<strong>in</strong>ical disease with no cl<strong>in</strong>ical signs.<br />
Treatment Considerations<br />
The economic impact <strong>of</strong> F. hepatica has been documented <strong>in</strong> several<br />
publications.(7-10) The f<strong>in</strong>ancial losses are stimulation for accurate<br />
evaluation <strong>of</strong> a herd or group <strong>of</strong> cattle. Consideration <strong>of</strong> the cow's role as a<br />
source <strong>of</strong> fluke <strong>in</strong>fection for their calves is also necessary. In a study <strong>of</strong> beef<br />
cows from the western United States, 19.2% <strong>of</strong> the cows showed evidence<br />
<strong>of</strong> liver fluke <strong>in</strong>fection at slaughter.(11) Cows <strong>in</strong>fected with liver flukes are<br />
a prime source <strong>of</strong> pasture contam<strong>in</strong>ation. Flukicide use <strong>in</strong> cows may help<br />
control pasture contam<strong>in</strong>ation with liver fluke eggs.<br />
In farm and ranch situations, a veter<strong>in</strong>arian can evaluate past years'<br />
experience, fecal exams, and liver checks from cattle slaughtered or<br />
necropsied on the farm, <strong>in</strong> order to decide on flukicide use. A feedlot<br />
veter<strong>in</strong>arian would seldom have this much <strong>in</strong>formation to base flukicide use<br />
on. Current livestock transportation services easily move cattle from fluke<br />
endemic areas to feedlots <strong>in</strong> any part <strong>of</strong> the United States. If the orig<strong>in</strong> <strong>of</strong><br />
<strong>in</strong>com<strong>in</strong>g feedlot cattle is known, liver fluke prevalence <strong>in</strong> the area <strong>of</strong><br />
orig<strong>in</strong> can be researched. If cattle are purchased from the same source over<br />
a period <strong>of</strong> years, past liver condemnation rates for fluke <strong>in</strong>fection can be<br />
exam<strong>in</strong>ed. The FLUKEFINDER system can also be used to check fecals <strong>of</strong><br />
arriv<strong>in</strong>g cattle for fluke eggs.<br />
Accurate data regard<strong>in</strong>g the fluke status <strong>of</strong> acquired cattle are <strong>of</strong>ten lack<strong>in</strong>g.<br />
In this case, tim<strong>in</strong>g <strong>of</strong> treatments should follow this rationale:<br />
! Cows can be treated at any time <strong>of</strong> year, s<strong>in</strong>ce they have had several<br />
seasons to acquire liver flukes.(11)<br />
! Northern calves should be treated for flukes as late <strong>in</strong> the fall as<br />
possible. Late fall treatment allows the maximum number <strong>of</strong> flukes <strong>in</strong><br />
the calves to mature <strong>in</strong>to adult flukes, which are most easily killed.(5)<br />
! Southeastern calves should ideally be treated for flukes beg<strong>in</strong>n<strong>in</strong>g <strong>in</strong><br />
September. This allows the last fluke picked up <strong>in</strong> June or early July<br />
to mature and be easily killed.(7)<br />
! Feedlot animals should be treated at entry. This provides the best<br />
<strong>in</strong>surance aga<strong>in</strong>st losses from flukes when the fluke status <strong>of</strong> arriv<strong>in</strong>g<br />
cattle is unknown.(10)<br />
Flukicides<br />
Two formulations <strong>of</strong> cattle flukicides are marketed by Merial <strong>in</strong> the United<br />
States. CURATREM® (clorsulon) drench is available to treat both mature<br />
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and immature flukes. IVOMEC® Plus (ivermect<strong>in</strong> and clorsulon) Injection<br />
treats suck<strong>in</strong>g lice, mange mites, grubs, and nematode parasites plus mature<br />
liver flukes. These products provide the outstand<strong>in</strong>g parasite control <strong>of</strong><br />
ivermect<strong>in</strong> plus the added <strong>in</strong>surance <strong>of</strong> fluke control.<br />
References<br />
1. Zimmerman G. Personal communication. Oregon State University.<br />
2. Sloss MW, Kemp RL, Zajac AM. Veter<strong>in</strong>ary Cl<strong>in</strong>ical Parasitology,<br />
6th edition; Iowa State University Press, 1994; 10.<br />
3. Faler K, Faler K. Improved detection <strong>of</strong> <strong>in</strong>test<strong>in</strong>al parasites. Modern<br />
Vet. Practice, April 1984; 273-276.<br />
4. Georgi JR. Parasitology for Veter<strong>in</strong>arians, 4th edition. W.B.<br />
Saunders, Co., 1986; 228, 248.<br />
5. Hoover RC, L<strong>in</strong>coln SD, Hall RF, Wescott R. Seasonal transmission<br />
<strong>of</strong> Fasciola hepatica to cattle <strong>in</strong> northwestern United States. JAVMA,<br />
1984. 184: 695-698.<br />
6. Malone JB, Loyacano AR, Hugh-Jones ME, Corkum KC. A threeyear<br />
study on seasonal transmission and control <strong>of</strong> Fasciola hepatica<br />
<strong>in</strong> cattle <strong>in</strong> Louisiana. Prev Vet Med, 1984; 3:131-141.<br />
7. Ross J G. Economics <strong>of</strong> Fasciola hepatica <strong>in</strong>fections <strong>in</strong> <strong>Cattle</strong>.<br />
British Vet J; 1970; 126: xiii-xv.<br />
8. Simpson JR, Kunkle W, Courtney CH, Shearer JK. Economic<br />
analysis <strong>of</strong> controll<strong>in</strong>g liver flukes. Agri-Practice, 1985; 6.<br />
9. Hope-Cawdrey MJ, Strickland KL, Convey A, Crowe PJ. Production<br />
effects <strong>of</strong> liver fluke <strong>in</strong> cattle. British Vet J, 1977; 133: 145-159.<br />
10. Johnson EG. Effects <strong>of</strong> liver flukes on feedlot performance. Agri-<br />
Practice, 1991; 12:33-35.<br />
11. Briskey DW, Scroggs MG, Hurtig FS. A prevalence survey <strong>of</strong> liver<br />
flukes (Distoma) <strong>in</strong> beef cows at slaughter <strong>in</strong> the western United<br />
States. Agri-Practice, 1994; 15: 8-11.<br />
Return to Table <strong>of</strong> Contents<br />
Veter<strong>in</strong>ary Pr<strong>of</strong>essional Services, Merial Limited,<br />
2100 Ronson Road, Isel<strong>in</strong>, NJ 08830-3077. Tel 1 888 637 4251<br />
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