Relationship Between Beef Production and Waterborne Parasitesdepartment/deptdocs.nsf/all/wat... · 2019-10-25 · Relationship Between Beef Production and Waterborne Parasites (Cryptosporidium

Relationship BetweenBeef Production

and Waterborne Parasites(Cryptosporidium spp. and Giardia spp.)

in the North Saskatchewan River BasinAlberta, Canada

– OVERVIEW –

Summary prepared byPatricia Mitchell. M. Sc., P. Biol.

June 2002

Research Team Members:S. Cooke, P. Mitchell, L. Roy, L. Gammie, M. Olson, C. Shepel,

T.L. Heitman, M. Hiltz, B. Jackson, S. Stanley, D. Chanasyk

Research Team Members:

S.E. Cooke, Alberta Agriculture, Food and Rural Development (Program Manager) P. Mitchell, Patricia Mitchell Environmental Consulting (formerly with Alberta Environment) L. Roy, Alberta Research Council L. Gammie, EPCOR M. Olson, University of Calgary C. Shepel, EPCOR T.L. Heitman, University of Calgary M. Hiltz, Alberta Research Council B. Jackson, Alberta Environment S. Stanley, EPCOR (formerly with University of Alberta) D. Chanasyk, University of Alberta

Research funding provided by the Canada-Alberta Beef Industry Development Fund, Alberta Agricultural Research Institute- Alberta Environmentally Sustainable Agriculture Program, and Health Canada. Substantial in-kind funding was provided by Alberta Environment, EPCOR, Alberta Research Council, University of Calgary, University of Alberta and Alberta Agriculture, Food and Rural Development.

For a copy of the technical report and for more information, please contact:Conservation and Development Branch,Alberta Agriculture, Food and Rural Development,#206, 7000 – 113 Street, Edmonton, Alberta T6H 5T6Ph; (780) 422-4385

The following is a summary of the technical report of the samename. The study deals primarily with the part of the NorthSaskatchewan River basin upstream of Edmonton and downstreamof Rocky Mountain House, except where noted otherwise. If youwould like more detail on how the research study was conducted orresults and conclusions, please see the technical report. To helpyou understand technical terms (in bold the first time used in thedocument), see the glossary at the end of this document.

Introduction

Cryptosporidium spp. (cryptosporidium)and Giardia spp. (giardia) are intestinalparasites that can infect humans, domesticlivestock and wildlife, as well as otheranimals, including birds. They are single-celled organisms called protozoa. Humansymptoms of infection include profuse, waterydiarrhea, fever and nausea. Although giardiainfections (popularly called “beaver fever”)are treatable with drugs, cryptosporidiuminfections are not. As well, cryptosporidiosiscan be life threatening for people with poorlyfunctioning immune systems, such as thosewith AIDS or cancer, infants and the elderly.Consequently, these parasites represent asignificant risk to public health.

Neither of these organisms can grow orreproduce outside of the digestive tracts ofwarm-blooded animals. These parasites formcysts or oocysts within the gut and are shedwith feces. The cyst or oocyst allows the

organism to survive outside of their host untilingested again, when they come out of theircyst and begin reproducing in the new host,and the cycle is repeated.

Cryptosporidium and giardia aretransmitted by ingesting contaminated feces ordrinking water. They are commonly found inaquatic environments. If they enter publicwater supplies, many people can becomeinfected, and they have been responsible foroutbreaks of waterborne disease worldwide.

In Canada, outbreaks have occurred inCollingwood, Ontario, Cranbrook andKelowna, British Columbia, and more recentlyin North Battleford, Saskatchewan.

Domestic livestock, including beef anddairy cattle, are often perceived to be theleading environmental source of waterborneparasites. Several studies in North Americahave also found these organisms in treatedsewage effluent and wildlife. Very fewstudies, however, have attempted to determinerelationships between these sources and concentrations of protozoan parasites in streams throughout a large watershed.

In the spring of 1997, very high levels ofcryptosporidium and giardia were present inthe North Saskatchewan River, the raw watersupply for the city of Edmonton. At the time,the river had high levels of turbidity, whichmade optimum treatment difficult (althoughthe two City plants were able to meetregulatory standards at all times). As a resultof the high number of parasites in the rawwater, a few organisms reached the finisheddrinking water, and a precautionary boil-wateradvisory was issued for people with poorlyfunctioning immune systems. Fortunately, nodisease outbreak occurred.

Cryptosporidium oocyst spp.

Giardia spp.cyst

The spp. after their scientific name means morethan one species may be present. There areseveral species of giardia and cryptosporidiumsuch as Cryptosporidium parvum andCryptosporidium muris. A cyst is a protectivecapsule produced by individual protozoa,whereas an oocyst is produced through sexualreproduction, like an egg. Note: Diagram not to scale.

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Because much of the North SaskatchewanRiver basin upstream of Edmonton is used forlivestock production, cattle were suggested asthe main contributor to the high levels of theseparasites in the river. In 1998, a study waslaunched to assess the relative contributionsfrom the three potential sources in thewatershed: agriculture, municipal sewageeffluent and wildlife.

The research team was multi-disciplinaryand included researchers from government,universities and private industry. It wasfunded through grants from the Canada-Alberta Beef Industry Development Fund, Alberta Agricultural Research Institute and Health Canada, as well as in-kind support from Alberta Agriculture, Food and RuralDevelopment, Alberta Environment, AlbertaResearch Council, EPCOR, the University ofAlberta and the University of Calgary.

The primary objectives of the study were toanswer the following questions:

- Do cattle contribute significant amounts of cryptosporidium and giardia to surface water compared with wildlife and municipal sewage?

- Do watersheds with high densities of cattle and other livestock contribute greater quantities of parasites to the North Saskatchewan River than non-agricultural (forested) watersheds?

Because much of the watershed above RockyMountain House had little agriculturalproduction, the study focused on the riverbasin between Rocky Mountain House andEdmonton. The three-year study included:

- Characterization of land use in the watershed;- Prevalence of parasites in fecal material from livestock, wildlife and sewage;

- Water quality assessment of 20 streams draining to the river, wastewater effluent and raw/ treated drinking water; and

- Statistical comparisons of various land use activities with water quality.

The research program was designed to becomprehensive – it covered all potential majorsources of protozoan parasites. But because itis nearly impossible to locate or measurespecific sources directly over such a largearea, indirect methods were used. Ifconcentrations of parasites in a stream werepositively correlated with a certain land usefactor, there is a good chance that the factorwas responsible (at least in part) for theconcentration.

The study did not attempt to deal withhuman health issues related to the ruralpopulation in the basin or whether theorganisms found in samples were alive orinfective. As well, different species insamples were not identified, because drinkingwater treatment plants have to assume that allspecies are potentially infective to human.

Watershed Characterization andSelection

The watershed of the North SaskatchewanRiver upstream of the city of Edmonton drains

2approximately 28,000 km . The study area,the basin draining the area from RockyMountain House to the city of Edmonton,

2consists of approximately 14,000 km or halfof the total upstream basin area (Figure 1). Onaverage, 61% of the flow in the river atEdmonton comes from the watershed aboveRocky Mountain House (average excludes thewinter months). Of the 20 study streams,Nordegg and Baptiste rivers are the largest.During the study, the 20 streams contributedan average of about 14% of the flow in theriver at Edmonton.

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Figure 1. Map of study area.

Contaminants in streams, including protozoan parasites, are usually transported byflowing water. Water that drains from thesurrounding land during snowmelt and rainstorms, carries various chemicals, organisms and soil particles - some natural and some the result of human activity. When human activities contribute any sort of chemical or biological substances that may adversely affect a desired use of water, it is called pollution.

Non-point source pollution is that from diffuse or undefined sources, mainly carried from the land in runoff. It is much more difficult to assess non-point sources of pollutants than those from point sources, such as from a pipe discharging from sewage treatment plants or drainage from confined livestock feeding operations. When a multitude of different land use activities occur in a watershed, the task of pinpointing sources becomes even more difficult.

Watershed-scale assessments of non-pointsources of contaminants require detailed land-based and water quality information. Not allareas of a watershed contribute contaminantsequally. To understand the link betweenwater quality in a creek or river and humanactivities in the watershed, we must firstidentify and understand characteristics of thewatershed: topography, geology, runoff potential, types of vegetation, density of people and livestock. Then, human activities that influence water quality the most can be identified and later targeted for remedial measures to reduce the movement of contaminants from land and water.

There are very few confined livestockfeeding operations in the basin - agricultural activities are widespread on the landscape as opposed to being concentrated in specific areas. Of the total number cattle in Alberta, about 5% are in the North Saskatchewan River basin above Edmonton. When adjusted for the land base suitable for agriculture in the province, this area is the third most intensive

N

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North SaskatchewanRiver Basin above Edmonton

ROCKY MOUNTAIN HOUSE

DEVON

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SPRUCEGROVE

STONY PLAIN

EDMONTON

3

area for beef cattle production in Alberta(about 9 animals per square kilometre,

2 compared with the highest at 10 per km ).Most of the cattle production is concentratedin the area between Drayton Valley and Edmonton.

Figure 2 shows livestock density in eachof the 20 study watersheds in animal unitequivalents per hectare. An animal unitequivalent is based on the size of the animal,and therefore amount of manure each type oflivestock would produce. For example, a calfwould produce less manure than a cow, so thenumber of calves is multiplied by 0.275.Cattle make up about 68% of the livestock inthese watersheds.

Trees and shrubs are the predominant landcover in the study area (about 40% of the area). Other types of land cover includeforage (21%), grassland (13%) and crops(10%). Most of the crop and forage land islocated between Drayton Valley andEdmonton, whereas much of the upper basinis treed.

About 76,000 people live in the river basinabove the city of Edmonton. Most of theregion is rural, although there are 18 hamlets,eight summer villages, four villages and fivetowns scattered throughout the area. Onlyabout 23,000 people are serviced bywastewater treatment facilities. Theremainder is serviced by private septic systems.

Figure 2: Density of total livestock in each study watershed in the North Saskatchewan River basin.

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Livestock density(animals unit equivalents/ha)

0 - 0.164

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0.164 - 0.2980.298 - 0.3650.365 - 0.5280.528 - 0.608No Data

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Overland runoff is an important factorinfluencing water quantity and quality. Amodel was used to estimate runoff potentialfrom information on soils, slope, erosion, landcover and distance to stream for each of the 20study watersheds. Forested streams rankedlowest for the likelihood of runoff, whereaswatersheds with more cleared land andagriculture ranked highest.

Agricultural intensity in the 20 studywatersheds, such as number of livestock andproportion of area farmed, was used to selectsix watersheds for more intensive study.Baptiste and Nordegg river watersheds havevery little livestock production and are mainlyforested. They are influenced primarily bywildlife. Throughout this report and thetechnical one, these control watersheds arecalled “non-agricultural or forested.” Fouragricultural watersheds were also chosen.Mishow and Tomahawk creek watershedswere ranked as having moderate agriculture,mostly cow-calf production. Compared withthe other study watersheds, Strawberry andWeed creek watersheds have a high density oflivestock, including beef cattle, dairy cattle,hogs and ranched elk and bison.

Parasite Prevalence

An obvious starting point for the studywas to find out whether protozoan parasiteswere present in fecal material from livestock,wildlife and municipal sewage. This part ofthe study was not designed to determinewhether or not parasites in animal feces orsewage actually did contaminate waterways,but only to determine whether the potential forcontamination was there.

Cooperation with land owners andproducers enabled the collection of fecalsamples from beef and dairy cattle, hogs,ranched elk and bison, and wildlife. Livestocksamples were generally collected in springwhen calves were about three to six weeksold. Seven cow-calf operations were sampled

in 1998, four operations were sampled in 1999 and six during 2000. Wildlife feces were collected in the spring immediately aftersnowmelt from 39 locations on forested landand along creeks in 18 of the 20 study watersheds. Thus, wildlife samples were collected from both agricultural and non-agricultural watersheds. Beaver and muskratfeces were collected from animals killed bytrappers or county workers, which were likelyfresher than feces of other wildlife collected from the ground. Even so, for other wildlife, samples collected from the ground, whetherfresh or dried, represent the potential forcontamination (in other words, the total“manure pack”) from wildlife – if parasites inold or frozen feces are dead, they pose no riskto waterways.

Municipal sewage samples were collected from 16 treatment facilities. These sampleswere collected from storage cells or inflowlines at the facilities, and therefore representraw or partly treated sewage, not treatedsewage effluent (see next section for results oftreated sewage effluent sampling). In total,more than 3800 samples were analyzed forparasite prevalence.

Prevalence was estimated as the percentage of the total number of samples inwhich parasites were present (i.e., positivesamples). For example, 1561 fecal samplesfrom beef cattle were examined. Of these,458 contained giardia cysts (29%) (see Table1). This is a fairly high prevalence.Concentration (number of parasites per gramof feces) in each positive sample was alsoestimated. For example, an average concentration of 3,742 cryptosporidium oocysts per gram was present in ranched elk,which is high compared with otheragricultural sources (no parasites weredetected in wild elk feces). A combination ofhigh prevalence and high concentration wouldrepresent the greatest risk for contaminatingsurface water.

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The results of the prevalence study confirm that agriculture, municipal sewage and wildlife are all potential sources of waterborne parasites. Except for muskrat, feces from beef cows and calves had the highest concentration and prevalence of giardia among all animals surveyed (see Table 1). The prevalence in partly treated sewage was high, but this is likely because parasites are more evenly distributed in sewage than in individual fecal samples. Thus, the chance that a sample would contain parasites is greater than for feces, resulting in higher prevalence.

Concentration in sewage is not reported, because the samples were greatly diluted by water, and therefore not representative of that in human feces.

The highest concentration of cryptosporidium was found in feces from ranched elk and bison. Cryptosporidium was not observed in feces from adult cattle, although samples were collected only in spring. For beef cattle feces, parasite concentration and prevalence varied considerably from year to year and between cattle operations.

Table 1. Prevalence and concentration of giradia cysts and cryptosporidium oocysts in fecal samples from livestock and wildlife, and prevalence in partially treated municipal sewage samples. Prevalence (Prev) is percentage of fecal samples with parasites. Concentration is number per gram in positive samples. NA = not applicable.

Livestock: Beef CattleDairy CattleHogsElk (ranch)Bison (ranch)

Horse

1561924038411

166

29181716150

1773

49

58011616

16652649

0

5433

NA

3180

2150

10

267254

037422369

0

700

NA

Total samplesAverage concentration

Municipal Sewage:

LynxMartenFisherPorcupine

DeerMooseElk (wild)Coyote

WolfHareSnow GooseCanada GooseGrouseSquirrel

MouseBeaverMuskrat

1438

64917734992

453205750152

33423

1931

0000

<1<10500000009

78

0000

1168168

01577

0000000

16549574

4196

0000

<1000000000020

0000

120000000000

5090

444

Total samplesAverage concentration

SampleSize Prev

(%)Average

ConcentrationPrev(%)

AverageConcentration

Giardia spp. Cryptosporidium spp.

Wildlife:

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Of the three major sources (livestock,wildlife and sewage), wildlife was the leastimportant source of cryptosporidium, in termsof prevalence. Of the nearly 2000 wildlife scatsamples collected, cryptosporidium waspresent in only nine samples, eight of whichwere beaver and one was deer. Although theprevalence in beaver samples was low, theconcentration was moderately high. The percentage of wildlife samples containing giardia was very low or zero for all species except muskrat and beaver. Even for beaver,less than 9% of samples contained giardia(compared with 78% for muskrat). Theconcentration of giardia in muskrat feces wasquite high. It is not clear why beaver feces hadlower prevalence of giardia than those ofmuskrat as both animals are exposed to similarcontaminated waterways.

Water Quality

Water flowing over the land can pick upparasites, nutrients, organic matter, fecalbacteria and other water quality constituents.This runoff gathers in streams and eventuallyreaches the North Saskatchewan River.Sometimes cysts and oocysts are attached tosoil particles or organic matter, or they may bepicked up directly by water and carried along.During runoff, such as spring snow melt andsummer rains, concentrations of manysubstances (including parasites) in the riverincrease. Therefore, the water sampling for thestudy focussed on runoff periods, although afew samples were collected during periods oflow river flow.

The study was designed to obtain more intensive information each year, because littlewas known about water-borne parasites in thebasin. During the three-year study, about 600water samples were collected from tributary streams, municipal sewage effluent andraw/treated drinking water.

Each year, water samples were collectedfrom 20 major tributaries in the NorthSaskatchewan River basin. This was calledthe “Longitudinal Survey.” This surveyprovided an overview of the water quality in avariety of streams, as well as year-to-yeardifferences.

In 1999, six streams were chosen from the20 streams for more intensive sampling, calledthe “Intensive Watershed Survey.” The sixstreams were chosen based on watershedcharacteristics, including livestock numbers,and were sampled in 1999 and 2000. Themain purpose of this survey was to be able torelate concentrations of parasites and otherwater quality characteristics with land use.Two of these streams were chosen becausevery few cattle and other livestock were in thewatersheds. These study watersheds werecalled “non-agricultural” or “forested” streamsand serve as controls or references for theother four watersheds (called “agriculturalstreams”). Also in 1999, samples werecollected upstream and downstream of threecattle operations to determine their impact onthe stream (“Upstream-Downstream Study”).

In 2000, two of the Intensive Watershedstreams were sampled at several sites todetermine whether some areas of thewatersheds contributed more parasites thanothers (“Synoptic Survey”).

Treated sewage effluent from the continuously discharging facilities which discharge directly to the river was alsosampled every two months or monthly year-round, and from municipal sewage lagoonswhen they discharged. As well, samples werecollected from the raw and treated drinkingwater at each drinking water treatment plantthat uses the North Saskatchewan River as asource.

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