giardiasis

Identity

Preferred Scientific Name

• giardiasis

International Common Names

• English: cockatiel feather mutilation syndrome; cockatiel feather syndrome; feather picking; giardiasis in birds; giardiasis in ruminants; giardiosis
• French: lambliose
• Russian: lambliasis

Overview

Antonie van Leeuwenhoek first described Giardia in 1681. Many names have been proposed for the genus such as Cercomonas (C.intestinalis) (Lambl, 1859); Giardia (Kunstler, 1882); Lamblia intestinalis (Blanchard, 1888); and Giardia lamblia (Kofoid and Christiansen, 1915), which was accepted for the human form. Filice (1952) proposed three species based on morphology of median bodies: G. duodenalis in mammals, birds, reptiles; G. muris in rodents; G. agilis in amphibians. Today there is still little agreement about the name, so G. intestinalis, G. duodenalis and G. lamblia are all used, although the latter two are now usually considered to be synonymous (Felice, 1952; Meyer, 1994; Farthing, 1999, Adam, 2001).

Giardia is found worldwide in humans and other animals primarily in the small intestine. As many as 40 species of Giardia have been identified based on the animal in which it was found: G. canis (dogs),G. cati (cats), G. bovis (cattle),G. caprae (sheep, goats), G. lamblia (humans). This idea of absolute host specificity is no longer considered correct (Meyer, 1994;Thompson et al., 2000).

Of Filice’s species, only G. duodenalis exhibits considerable genetic diversity. Since cysts of G. duodenalis cannot be distinguished morphologically, methods have been developed to characterize isolates, such as DNA amplification and sequencing, isoenzyme analysis, pulsed-field gel electrophoresis, restriction fragment length polymorphism analysis and polymerase chain reaction (Wolfe, 1992; Farthing, 1999; Adam, 2001). Using these techniques, researchers have identified new species of Giardia: G. microti in voles and muskrats (van Keulen et al., 1998), G. ardeae in herons(Erlandsen et al., 1990); G. psittaci in parakeets (Erlandsen and Bemrick, 1987). Two genetic assemblages worldwide, "Polish" (Groups 1 and 2, Assemblage A) and "Belgian" (Group 3, Assemblage B) have been identified which infect humans and other species of mammals (van Keulen et al., 1995; Ey et al., 1996, 1997; Monis et al., 1999; Thompson, et al., 2000). A ‘hoofed stock’ genotype has also been identified in pigs, sheep, goats, cattle and alpaca that is not found in humans (Ey et al., 1997). Hunt et al. (2000) has reported two different isolates in calves - Type I and Type II.

Giardia is important because it may/may not cause clinical illness, particularly in young animals, resulting in reduced weight gain which has economic impact for the producer. Problems are most often seen in high-density production, or in animals otherwise debilitated by disease or malnutrition. Different Giardia isolates may/may not have zoonotic potential.

Hosts/Species Affected

Age, health status, hygiene of environment, nutrition all are risk factors for Giardia infection. Young become infected from environmental contamination or from animal to animal contact. Infected animals are more often seen when densely housed with a large number of animals, when animals of all ages are housed together, and when the quality and amount of colostrum fed is inadequate. A cool, damp environment allows longer survival of cysts that increases the risk of infection in animals. Nesvadba et al. (1982) reported no predilection for giardiasis in any cattle breed.

Poultry

Giardia is primarily seen in pet birds such as cockatiels, budgerigars, lovebirds, parakeets, conures, parrots and macaws (Box, 1981; Scholtens et al., 1982; Fudge and McEntee, 1986; Filippich et al., 1998). Feather picking (‘cockatiel feather syndrome’) is a common sign. It is also seen in wild birds such as great blue heron (Georgi et al., 1986; Erlandsen et al., 1990), ibis (Forshaw et al., 1992; McRoberts et al., 1996; Upcroft et al., 1997), stork (Franssen et al., 2000), American bittern, little blue heron, western meadowlark, swamp sparrow (Travis, 1939), and poultry, waterfowl (Fudge and McEntee, 1986).

Young birds are more susceptible, can have high mortality and in chronic infections see recurrent diarrhoea and weight loss (Filippich et al., 1998). This may be the result of how birds are raised in very densely populated environments (Pesek, 2001). Prevention is based on good hygiene and management, keeping living quarters dry, reducing faecal-oral transmission by using wire-floored cages, and elevating food and water containers, (Filippich et al., 1998). Quarantine of new birds, avoiding overcrowding, and treatment of birds with clinical signs will decrease Giardia in a flock (Pesek, 2001).

Pigs

Giardia is seen in weaned 1-2 month old pigs (Koudela, et al., 1991); in weanlings and nursing piglets (Xiao et al., 1994a); and in all ages of feral pigs (Atwill et al., 1997). Most infected animals are asymptomatic, although diarrhoea may occur (Koudela et al., 1991; Xiao, et al., 1994a). Risk of infection is higher when pigs housed on porous concrete floor than on slotted and wired floors, and infection can be delayed on well managed farms (Xiao et al., 1994a). Prevalences of 44% (Koudela et al., 1991) and 2.5% (Ajayi et al., 1988) have been reported in domestic pigs and 7.6% have been reported in feral pigs (Atwill et al., 1997).

Sheep and Goats

Giardia is primarily a problem in lambs and kids, usually with diarrhoea (Deas, 1959; Padmavathi, et al., 1978; Sutherland and Clarkson, 1983; Kiorpes, et al., 1987; Suteu et al., 1987a, 1987b;Taylor et al., 1993; Xiao et al., 1994b; Olson et al., 1995; Koudela and Vitovec, 1998; Majewska et al., 1998). In lambs, prevalence of infection from 19% to 68.6% has been reported (Taminelli and Eckert, 1989; Buret et al., 1990; Taylor et al., 1993) and in kids prevalence of infection from 10% to 50% have been reported (Taminelli and Eckert, 1989). Adult sheep have been reported to have Giardia with prevalences of 3.6 to 5.3% (Buret et al., 1990; Taylor et al., 1993), and adult goats have been reported with a prevalence of 18% (Suteu et al., 1987a). Xiao et al. (1994b) reported pre- and post-partum shedding of cysts in ewes. This periparturient cyst shedding increases the likelihood of lamb contamination while in maternity pens.

Cattle

Giardia is primarily found in animals less than six months of age, but cattle of all ages can have Giardia in low numbers. Infection may/may not be associated with diarrhoea. (Deshpande and Shastri, 1981; Nesvadba et al., 1982; Buret et al., 1990; Xiao et al., 1993, 1994c; Rings and Rings 1996; Olson et al., 1997a, 1997b; O’Handley et al., 1999, 2000a; Wade et al., 2000a, 2000b). Prevalence of infection has been reported from 0.16 to 73% (Taminelli and Eckert, 1989; Diaz et al., 1996; Quilez, 1996; Olson et al., 1997a, 1997b; Bednarska et al., 1998; Majewska et al., 1998; Ruest et al., 1998; Vilchez and Pote, 1999; O’Handley et al., 1999, 2000a); Fayer et al., 2000; Wade et al., 2000b). Animals have been reported to be at higher risk of infection in the summer (Wade et al., 2000a) or in spring (Xiao et al., 1993), and when allowed to nurse the dam (Quigley et al., 1994).

Buffaloes

In Greece, Giardia infection was reported in buffalo with 100% prevalence (Himonas et al., 1998).

Distribution

Giardia is found worldwide in mammals, including humans, and birds, reptiles, amphibians.

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Pathology

Infection with Giardia when asymptomatic shows no abnormality, but if symptomatic many changes are seen. Gross signs seen include villous atrophy, crypt hyperplasia and distortion, mucous and hemorrhagic diarrhoea, dark red, thickened mucosa in folds (Supperer, 1952; Botti, 1956, Kulda and Nohynkova, 1978; Kiorpes, et al., 1987; St Jean, 1987; Wolfe, 1992; Rings and Rings, 1996; Ruest et al., 1997; Koudela and Vitovec 1998; Farthing, 1999).

Histological signs seen include moderate to severe diffuse inflammation in the jejunal chorion; cellular infiltrate of the lamina propria with mononuclear cells especially plasmocytes; purulent cryptitis in the proximal jejunum; epithelial cell damage, blunting of the microvillous border of epithelial cells, and no eosinophilia (St Jean, 1987; Wolfe, 1992; Buret, 1994; Rings and Rings, 1996; Ruest et al., 1997; Koudela and Vitovec, 1998).

Birds show histologic changes classified as enterohepatitis, with a distended proventriculus, dehydration, hyperaemic intestines, and watery yellow to green droppings. An increase in serum SGOT has been reported (Panigraphy et al., 1978; Scholtens et al., 1982; Fudge and McEntee, 1986; Filippich et al., 1998; Bourke, 2001).

Diagnosis

Clinical diagnosis comes from the observation of certain key symptoms: abdominal pain, diarrhoea with blood or mucus, nausea, poor weight gain, unthrifty, soiling of fur or feathers, and dry wool in sheep (Turner and Murnana, 1932; Deas, 1959; Padmavathi et al., 1978; Scholtens et al., 1982; Kiorpes et al., 1987; Issac-Renton, 1991; Olson et al., 1995; Filippich et al., 1998; Bourke, 2001).

See Pathology section.

Acute giardiasis with diarrhoea must be distinguished from viral, bacterial, and other protozoan infections. Giardia has a longer incubation period than most other enteric pathogens. Chronic giardiasis must be distinguished from other protozoan and helminth infections, malabsorption, irritable bowel syndromes, and inflammatory bowel disease. It may mimic duodenal ulcer, hiatal hernia, gallbladder or pancreatic disease (Wolfe, 1992).

Microscopic examination of faeces for the detection of cysts by mucosal or wet faecal smears is inexpensive and quickly processed. The slides can be examined unstained, or by using a variety of stains such as Giemsa, Ziehl-Neelsen or iodine (Deas, 1959; Scholtens et al., 1982; Fudge and McEntee, 1986; Isaac-Renton, 1991; Wolfe, 1992; Rings and Rings, 1996; Koudela and Vitovec, 1998; Farthing, 1999). Flotation methods may be passive, or use a centrifugation concentration technique. Saturated sugar and salt solutions are too hypertonic causing distortion of Giardia cysts, so 1.18 spg zinc sulfate is the solution of choice (Kiorpes et al., 1987; Isaac-Renton, 1991; Rings and Rings, 1996). Since cysts are shed intermittently, examination of multiple fecal samples is recommended (Isaac-Renton, 1991; Wolfe, 1992).

Immunological tests have been developed for the detection of antibodies produced by the animal, or of antigens produced by the protozoa (Rosoff et al., 1989; Faubert, 1996; Garcia and Shimizu, 1997). Direct fluorescence antibody tests, and enzyme-linked immunosorbent assays (ELISA) are examples of two kinds of immunological tests commercially available (Mohan, 1993; Mank et al., 1997; Behr et al., 1997). An ELISA is more expensive then using a microscopy technique, but has been reported to be more sensitive (Behr et al., 1997; Mank et al., 1997). Antibodies in serum are found in infected and non-infected people, especially in endemic areas, so may not be useful for diagnosis (Wolfe, 1992; Farthing, 1999). Immunofluorescent staining of smears is used, but requires the use of a fluorescent microscope (Mohan, 1993; Xiao et al., 1994b, 1994c).

Biopsies, duodenal aspirates, endoscopy and radiographs of the small intestine are other available diagnostic tests (Kulda and Nohynkova, 1978; Wolfe, 1992; Farthing, 1999). Differences in the success of use of tests is related to technical expertise, care used in performing tests, and quality of reagents. No one method or combination of methods can detect all infections (Wolfe, 1992).

For field use or in developing countries, mucosal or wet faecal smears (wet mounts) with or without staining are inexpensive and quickly processed. Slides, cover slips and a microscope are the only equipment needed. All immunological testing is more expensive and requires specialized equipment.

Immunology of Disease

Both humoral and cellular immune responses are generated by the host to control the infection, to clear the organism, and to develop protective immunity. T-cell function is necessary for resistance development. Anti-Giardia antibodies, IgG, IgM, IgA, are detected during the course of infection. IgG persists for weeks or months. Antigenic variation (immunodominant cystein rich surface antigens) has been found on the surface of trophozoites whose purpose may be evasion of the host immune defense, and to enable organisms to survive in different intestinal environments (Wolfe, 1992; Faubert, 1996; Nash, 1997; Farthing, 1999; Adam, 2001).

List of Symptoms/Signs

Disease Course

Three clinical forms of infection are seen in animals: asymptomatic; acute disease; and chronic disease (Farthing, 1999). Clinical variation may relate to host factors (genetic or environmentally related), or to severity of infection in intestine. Animals with normal immune systems develop immunity with resolved signs (Sutherland and Clarkson, 1983; Hunt et al., 2000).

An asymptomatic animal is infected but has no clinical signs (Meyer, 1994; Rings and Rings 1996). Acute disease has signs of watery diarrhoea, with/without blood, which is short-lived (self-limiting within 2-4 weeks), mild fever, depression, dehydration (Isaac-Renton, 1991; Meyer 1994). Chronic disease has signs of diarrhoea with intestinal malabsorption, reduced appetite, weight loss, failure to thrive syndrome, little to no fever, semi-formed faeces, steatorrhoea, and anaemia. Immunodeficiency is associated with chronic giardiasis (Isaac-Renton, 1991; Meyer 1994; Rings and Rings, 1996; Farthing, 1999).

Diarrhoea is caused by luminal factors such as the trophozoites’effect on bile salts and fat absorption, inhibition of trypsin activity, possible disturbances in intestinal motility; and mucosal factors such as lectin activity that promotes adherence of parasite and contributes to brush border lesions, decreasing sodium mediated glucose transport (Rings and Rings, 1996).

Epidemiology

Giardia is transmitted by the faecal-oral route via contaminated food and water, or by animal to animal contact. Risk factors for transmission include age, health status, temperature and moisture of environment, use of surface or untreated water, contaminated food, and break down in hygiene. High-risk animals are the young and immunocompromised. It is unknown how many cysts are needed to cause infection, but a susceptible host only needs a few cysts. The prevalence rates and number of cysts excreted varies from day to day. Wild and domestic animals may be reservoirs (Isaac-Renton, 1991; Farthing, 1999).

Giardia has a direct life cycle that takes 1-75 days, usually 7-9 days, to complete and has two life stages: trophozoite and cyst. If there is increased intestinal motility, trophozoites do not become cysts and are lost to the environment and quickly die. Cysts form in the lower small intestine, leave the host in faeces, and may/may not be immediately infective. Cysts are the environmentally resistant stage that is able to infect a new host (Meyer and Jarroll, 1980; Meyer, 1994; Rings and Rings, 1996; Farthing, 1999).

There are no intermediate hosts needed to complete the life cycle. Mechanical vectors may move cysts from one place to another via freshwater clams (Graczyk et al., 1997, 1999a, 1999b); flies (Doiz et al., 2000), birds (Graczyk et al., 1998), and fomites such as machinery, vehicles, equipment, feeding buckets, and clothing.

Impact: Economic

Giardiasis has its greatest impact on the young who may have reduced weight gain that keeps them unmarketable longer. Even with no difference in feed intake, feed efficiency is impaired, and there is lower carcass weight in infected lambs (Olson et al., 1995).

Zoonoses and Food Safety

Humans are reservoirs for other humans, and wild and domestic animals. Molecular epidemiology has demonstrated that forms of Giardia that infect humans also occur in other species of mammals, and that several host-adapted genotypes might represent distinct species. The greatest zoonotic risk is from genotypes in Assemblage A and to a lesser extent in Assemblage B. The ability to genotype may be a powerful predictive tool for providing direct evidence of the source of outbreak or of cysts (Majewska et al., 1998; Farthing, 1999; Thompson et al., 2000). This zoonotic potential means that veterinarians must be concerned about not only the health of animals, but of the humans who handle infected animals (Rings and Rings, 1996).

Giardia infections occur throughout the year suggesting that water is either contaminated often or the cysts are long lived. Cysts in water remain viable longer when kept at cold temperatures. When kept at 4°C or less, 40% of Giardia cysts are still viable after three months. No cysts survive longer than three weeks in water at 37°C. Manure spreading from agricultural operations may move cysts from the barn to fields. Pastured or free-roaming animals defecate wherever they may be and contribute to environmental contamination. Water may be contaminated by runoff from these fields, or by animals defecating in the water. An increased risk of infection has been reported with contamination of barns and pastures (Ruest et al., 1998).

Foodborne outbreaks in humans are not common but have been reported. Outbreaks of giardiasis have been associated with eating contaminated home prepared salmon, fruit salad, cold noodle salad, and in restaurants such foods as sandwiches, vegetables from a salad bar, and iced drinks (White, et al., 1989, Porter, et al., 1990, Quick et al., 1992, Mintz et al., 1993).

Waterborne outbreaks in humans may occur when water is untreated, inadequately treated, or when there is contamination of the distribution system, such as when there is mixing of water with raw sewage. Surface water is most often involved, although ground water may be contaminated. These protozoa may be found in water in the absence of E. coli, the normal indicator organism for faecal contamination (Craun, 1984; Rabbini and Islam, 1994).

Disease Treatment

Giardia sp. infections in humans and other animals are treated with metronidazole, quinacrine, furazolidone and tinidazole (Upcroft and Upcroft, 1990; Rabbini and Islam, 1994). Sutherland and Clarkson (1984) reported treating kids with metronidazole (one oral dose of 600 mg/goat). Metronidazole and furazolidone are mutagenic, and quinacrine crosses the placenta so they are not approved for use in food animals in most developed countries (Edlind et al., 1990, Rings and Rings, 1996). Resistance of Giardia sp. to these drugs has been seen in recent years. This can be prevented by prudent administration, compliance of proper usage and avoiding their use as a prophylactic. (Upcroft et al., 1990; Upcroft and Upcroft, 1993; Townson et al., 1992).

Treatment of Giardia sp. infection has been successful using albendazole and fenbendazole that suppress cyst excretion by Giardia-infected calves (Reynoldson, 1994; Rings and Rings, 1996; Xiao et al., 1996). Xiao et al., (1996) reported using 20 mg/kg albendazole once daily/3 days orally and 1mg/kg^-1 fenbendazole two times daily/3 days orally in calves. Fenbendazole (5mg/kg once daily/3 days) is an effective treatment in calves to eliminate Giardia, although multiple treatments may be required in infected animals. It is economical, has clinical benefit (fewer days with diarrhoea), and reduces the number of cysts being shed (O’Handley et al., 1997, 2000b). Benzimidazoles are inhibitors of polymerization of tubulin to microtubules that are components of flagella, the median body and the ventral disk of trophozoites. It is likely that the action inhibits attachment to the intestinal mucosa, not the movement by the flagella (Edlind et al., 1990; Jarroll, 1994; Adams, 2001). Flubendazol has been used to treat pigs for parasites including Giardia (Zizlavsky et al., 1998).

Alternative treatments use plant preparations. Methanolic extracts of 21 of 36 taxa of plants in Kenya and Tanzania were lethal or inhibited growth of Giardia (Johns et al., 1995), and isoflavones from Dalbergia frutescens stem bark in Venezuela hold promise, especially formononetin (Khan et al., 2000). Anti-giardial activity of a powdered preparation of Yucca schidigera (yucca) was tested in vitro and in vivo in gerbils and lambs. Lambs shed fewer cysts after several days of treatment, but a corresponding decline in prevalence was not seen (McAllister et al., 2001).

Filippich et al. (1998) treated birds with metronidazole in drinking water (800 mg/L of water for 5 days) and Panigraphy et al. (1978) used dimetridazole at a concentration of 0.02% water.

Histostat in feed and copper sulfate in water is used to treat histomoniasis, trichomoniasis and hexamitiasis in poultry (Penpages, 1999). Drugs with dosages are listed in Penpages (1999) and in Fudge and McEntee (1986). One holistic treatment for birds uses a combination of lactulose, Echinacea and apple cider vinegar in drinking water, but it is not a 100% cure. Before and after any treatment it is important to disinfect cages using10% bleach (Bourke, 2001).

Prevention and Control

Prevention is attained when there is interruption of transmission, or prevention of ingestion of cysts. Young stock management that includes adequate colostrum and nutrition, lack of animal to animal contact, a clean and dry environment, separation of animals of different ages, cleaning and disinfection of housing equipment and feeding utensils, keeping feed free from faecal contamination, handling of healthy animals before sick animals, and using prophylactic measures such as vaccines is the best place to start. Since Giardia is found in many animals throughout the world and has the potential to be zoonotic there is a large uncontrollable reservoir in the environment. Treatment of water and disposal of manure so water is not contaminated are ways to control cysts in the environment (Rings and Rings, 1996; Farthing, 1999; Wolfe, 1992). A vaccine for dogs and cats to prevent clinical signs and reduce cyst shedding was recently developed (Olson et al., 2000), but no vaccines are available for other species at this time.

Cysts are killed by boiling, drying, freezing and heating. Heating manure to 65°C takes 24 hours to kill Giardia cysts, which suggests that composting manure properly may kill the cysts. Anaerobic digestion of sludge has been shown to inactivate cysts almost 100% (Gavaghan, et al., 1993; Van Praagh et al., 1993) and waste stabilization ponds in Kenya and France remove over 99% of the cysts (Grimason et al., 1993; 1996). Kay et al. (1998) reported that Giardia cysts were completely destroyed by alkaline hydrolysis. Most disinfectants, especially chlorine based ones, do not kill the cysts at the dilutions recommended by manufacturers for use around animals (Jarroll et al., 1984). Quaternary ammonium compounds and Alcide products rapidly inactivate cysts (Zimmer et al., 1988).

References

Adam RD, 2001. Biology of Giardia lamblia. Clinical Microbiological Revue, 14(3):447-475.

Ajayi JA; Arabs WL; Adeleye GA, 1988. Helminths and protozoa of pigs on the Jos Plateau, Nigeria: occurrence, age incidence and seasonal distribution. Bulletin of Animal Health and Production in Africa, 36(1):47-54; 26 ref.

Al-Tukhi MH; Al-Ahdal MN; Das SR; Sadiqi S; Siddiqui Y; Ackers J; Peters W, 1991. Pathogenicity and antigenic components of excysted Giardia lamblia isolated from patients in Riyadh, Saudi Arabia. American Journal of Tropical Medicine and Hygiene, 45(4):442-452; 33 ref.

Atwill ER; Sweitzer RA; Pereira Mdas GC; Gardner IA; Vuren Dvan; Boyce WM, 1997. Prevalence of and associated risk factors for shedding Cryptosporidium parvum oocysts and Giardia cysts within feral pig populations in California. Applied and Environmental Microbiology, 63(10):3946-3949; 34 ref.

Bednarska M; Bajer A; Sinski E, 1998. Calves as a potential reservoir of Cryptosporidium parvum and Giardia sp. Annals of Agricultural and Environmental Medicine, 5(2):135-138; 22 ref.

Behr MA; Kokoskin E; Gyorkos TW; Cédilotte L; Faubert GM; Maclean JD, 1997. Laboratory diagnosis for Giardia lamblia infection: a comparison of microscopy, coprodiagnosis and serology. Canadian Journal of Infectious Diseases, 8(1):33-38; 49 ref.

Botti L, 1956. Prima segnalazione in italia della Giardiasi del vitello. Indagni biometriche sul parassita e sua identificazione nella specie Giardia bovis Fantham 1921. Revista di Parassitologia, 17:129-142.

Bourke AM, 2001. Giardia in cockatiels. 'Tiel' Times, www.Cockatiel.org/articles/Giardia.html.

Box ED, 1981. Observations on Giardia of budgerigars. Journal of Protozoology, 28(4):491-494.

Buret A, 1994. Pathogenesis - how does Giardia cause disease?. Giardia: from molecules to disease., 293-315; 107 ref.

Buret A; DenHollander N; Wallis PM; Befus D; Olson ME, 1990. Zoonotic potential of giardiasis in domestic ruminants. Journal of Infectious Diseases, 162(1):231-237; 31 ref.

Craun GF, 1984. Waterborne outbreaks of giardiasis. Current status. Giardia and giardiasis - biology, pathogenesis, and epidemiology., 243-261; 47 ref.

Deas DW, 1959. Giardiasis in a lamb. Veterinary Record, 71:705.

Deschiens R; Lamy L, 1946. Etude morphologique des Giardia du mouton et des ruminants. Annale Institut Pasteur (Paris), 72:95-103.

Deshpande PD; Shastri UV, 1981. Incidence of Giardia infection in calves in Maharashtra State, India. Tropical Animal Health and Production, 13:14.

Díaz V; Campos M; Lozano J; Manas I; González J, 1996. Aspects of animal giardiosis in Granada province (southern Spain). Veterinary Parasitology, 64(3):171-176; 18 ref.

Doiz O; Clavel A; Morales S; Varea M; Castillo FJ; Rubio C; Gomez-Lus R, 2000. House fly (Musca domestica) as a transport vector of Giardia lamblia. Folia Parasitologica, 47:330-331.

Erlandsen SL; Bemrick WJ, 1987. SEM evidence for a new species, Giardia psittaci.. Journal of Parasitology, 73(3):623-629; 18 ref.

Erlandsen SL; Bemrick WJ; Wells CL; Feely DE; Knudson L; Campbell SR; Keulen Hvan; Jarroll EL, 1990. Axenic culture and characterization of Giardia ardeae from the great blue heron (Ardea herodias). Journal of Parasitology, 76(5):717-724; 31 ref.

Ey PL; Bruderer T; Wehrli C; Köhler P, 1996. Comparison of genetic groups determined by molecular and immunological analyses of Giardia isolated from animals and humans in Switzerland and Australia. Parasitology Research, 82(1):52-60; 31 ref.

Ey PL; Mansouri M; Kulda J; Nohynková E; Monis PT; Andrews RH; Mayrhofer G, 1997. Genetic analysis of Giardia from hoofed farm animals reveals artiodactyl-specific and potentially zoonotic genotypes. Journal of Eukaryotic Microbiology, 44(6):626-635; 41 ref.

Fantham HB, 1921. Some parasitic protozoa found in South Africa: IV. South African Journal of Science, 18(1-2):164-170.

Farthing MJG, 1999. Giardiasis. In: Gilles HM, ed. Protozoal Diseases. New York, USA: Oxford University Press, 562-585.

Faubert GM, 1996. The immune response to Giardia. Parasitology Today, 12(4):140-145; 57 ref.

Fayer R; Trout JM; Graczyk TK; Lewis EJ, 2000. Prevalence of Cryptosporidium, Giardia and Eimeria infections in post-weaned and adult cattle on three Maryland farms. Veterinary Parasitology, 93(2):103-112.

Filice FP, 1952. Studies on the cytology and life history of a Giardia from the laboratory rat. University of California Publications in Zoology, 57:53-146.

Filippich LJ; McDonnell PA; Munoz E; Upcroft JA, 1998. Giardia infection in budgerigars. Australian Veterinary Journal, 76(4):246-249; 29 ref.

Forshaw D; Palmer DG; Halse SA; Hopkins RM; Thompson RCA, 1992. Giardia in straw-necked ibis (Threskiornis spinicollis) in Western Australia. Veterinary Record, 131(12):267-268; 18 ref.

Franssen FFJ; Hooimeijer J; Blankenstein B; Houwers DJ, 2000. Giardiasis in a white stork in the Netherlands. Journal of Wildlife Diseases, 36(4):764-766.

Fudge AM; McEntee L, 1986. Avian Giardiasis: Syndromes, diagnosis, and therapy. Proceedings of Association of Avian Veterinarians, 155-164.

Garcia LS; Shimizu RY, 1997. Evaluation of nine immunoassay kits (enzyme immunoassay and direct fluorescence) for detection of Giardia lamblia [Giardia duodenalis] and Cryptosporidium parvum in human fecal specimens. Journal of Clinical Microbiology, 35(6):1526-1529; 41 ref.

Gavaghan PD; Sykora JL; Jakubowski W; Sorber CA; Sninsky AM; Lichte MD; Keleti G, 1993. Inactivation of Giardia by anaerobic digestion of sludge. Water Science and Technology, 27(3-4):111-114; 6 ref.

Georgi ME; Carlisle MS; Smiley LE, 1986. Giardiasis in a great blue heron (Ardea herodias) in New York State: another potential source of waterborne giardiasis. American Journal of Epidemiology, 123(5):916-917; 7 ref.

Graczyk TK; Cranfield MR; Conn DB, 1997. In vitro phagocytosis of Giardia duodenalis cysts by hemocytes of the Asian freshwater clam Corbicula fluminea. Parasitology Research, 83(8):743-745; 22 ref.

Graczyk TK; Fayer R; Conn DB; Lewis EJ, 1999. Evaluation of the recovery of waterborne Giardia cysts by freshwater clams and cyst detection in clam tissue. Parasitology Research, 85(1):30-34; 21 ref.

Graczyk TK; Fayer R; Trout JM; Lewis EJ; Farley CA; Sulaiman I; Lal AA, 1998. Giardia sp. cysts and infectious Cryptosporidium parvum oocysts in the feces of migratory Canada geese (Branta canadensis). Applied and Environmental Microbiology, 64(7):2736-2738; 18 ref.

Graczyk TK; Thompson RCA; Fayer R; Adams P; Morgan UM; Lewis EJ, 1999. Giardia duodenalis cysts of genotype A recovered from clams in the Chesapeake Bay subestuary, Rhode River. American Journal of Tropical Medicine and Hygiene, 61(4):526-529; 38 ref.

Grimason AM; Smith HV; Thitai WN; Smith PG; Jackson MH; Girdwood RWA, 1993. Occurrence and removal of Cryptosporidium spp. oocysts and Giardia sp. oocysts in Kenyan waste stabilisation ponds. Water Science and Technology, 27(3-4):97-104; 24 ref.

Grimason AM; Wiandt S; Baleux B; Thitai WN; Bontoux J; Smith HV, 1996. Occurrence and removal of Giardia sp. cysts by Kenyan and French waste stabilisation pond systems. Water Science and Technology, 33(7):83-89; 18 ref.

Hatheway CL, 1990. Toxigenic clostridia. Clinical Microbiology Reviews, 3(1):66-98; 355 ref.

Himonas CA; Antoniadou-Soteriadou KS; Sotiraki ST; Papazahariadou MG, 1998. Intestinal protozoa of animals in the Macedonia region of Greece. Deltion te^macron~s Elle^macron~nike^macron~s Kte^macron~niatrike^macron~s Etaireias = Bulletin of the Hellenic Veterinary Medical Society, 49(4):300-306; 77 ref.

Hsu BingMu; Huang ChihPin; Hsu ChihLi; Hsu YeongFua; Yeh JH, 1999. Occurrence of Giardia and Cryptosporidium in the Kau-Ping river and its watershed in southern Taiwan. Water Research (Oxford), 33(11):2701-2707; 19 ref.

Hunt CL; Ionas G; Brown TJ, 2000. Prevalence and strain differentiation of Giardia intestinalis in calves in the Manawatu and Waikato regions of North Island, New Zealand. Veterinary Parasitology, 91(1/2):7-13; 15 ref.

Iburg T; Gasser RB; Henriksen SA, 1996. First record of Giardia in cattle in Denmark. Acta Veterinaria Scandinavica, 37(3):337-341.

Isaac-Renton JL, 1991. Laboratory diagnosis of giardiasis. Clinics in Laboratory Medicine, 11(4):811-827; 81 ref.

Jarroll EL, 1994. Biochemical mechanisms of antigiardial drug action. Giardia: from molecules to disease., 329-337; 31 ref.

Jarroll EL; Hoff JC; Meyer EA, 1984. Resistance of cysts to disinfection agents. Giardia and giardiasis - biology, pathogenesis, and epidemiology., 311-328; 51 ref.

Johns T; Faubert GM; Kokwaro JO; Mahunnah RLA; Kimanani EK, 1995. Anti-giardial activity of gastrointestinal remedies of the Luo of East Africa. Journal of Ethnopharmacology, 46(1):17-23; 11 ref.

Kay GI; Weber PB; Evans A; Venezia RA, 1998. Efficacy of alkaline hydrolysis as an alternative method for treatment and disposal of infectious animal waste. Contemporary Topics in Laboratory Animal Science, 37(3):43-46.

Keulen Hvan; Feely DE; Macechko PT; Jarroll EL; Erlandsen SL, 1998. The sequence of Giardia small subunit rRNA shows that voles and muskrats are parasitized by a unique species Giardia microti. Journal of Parasitology, 84(2):294-300; 27 ref.

Keulen Hvan; Homan WL; Erlandsen SL; Jarroll EL, 1995. A three nucleotide signature sequence in small subunit rRNA divides human Giardia in two different genotypes. Journal of Eukaryotic Microbiology, 42(4):392-394; 24 ref.

Khan IA; Avery MA; Burandt CL; Goins DK; Mikell JR; Nash TE; Azadegan A; Walker LA, 2000. AntiGiardial activity of isoflavones from Dalbergia frutescens bark. Journal of Natural Products, 63(10):1414-1416.

Kiorpes AL; Kirkpatrick CE; Bowman DD, 1987. Isolation of Giardia from a llama and from sheep. Canadian Journal of Veterinary Research, 51(2):277-280; 16 ref.

Koudela B; Nohynková E; Vítovec J; Pakandl M; Kulda J, 1991. Giardia infection in pigs: detection and in vitro isolation of trophozoites of the Giardia intestinalis group. Parasitology, 102(2):163-166; 13 ref.

Koudela B; Vítovec J, 1998. Experimental giardiasis in goat kids. Veterinary Parasitology, 74(1):9-18; 23 ref.

Kulda J; Nohynkoc E, 1978. Flagellates of the human intestine and of intestines of other species VI. Giardia and Giardiasis. In: Kreier JP, ed. Parasitic Protozoa. - Intestinal Flagellates, Histomonads, Trichomonads, Amoeba, Opalinids, and Ciliates, Vol. 2. New York, USA: Academic Press, 69-104.

Majewska AC; Kasprzak KW; Werner A, 1998. Prevalence of Giardia infection in livestock and the possibility of zoonotic transmission. Acta Parasitologica 43(1):1-3.

Mank TG; Zaat JOM; Deelder AM; Eijk JTMvan; Polderman AM, 1997. Sensitivity of microscopy versus enzyme immunoassay in the laboratory diagnosis of giardiasis. European Journal of Clinical Microbiology & Infectious Diseases, 16(8):615-619; 15 ref.

Mazanowski A, 1999c. A comparison of finishing performance of 17- and 24-week-old geese from experimental flocks and Koluda White geese on oats-based diet. Roczniki Naukowe Zootechniki, 26(1):87-102; 17 ref.

McAllister TA; Annett CB; Cockwill CL; Olson ME; Wang Y; Cheeke PR, 2001. Studies on the use of Yucca schidigera to control giardiosis. Veterinary Parasitology, 97(2):85-99; 51 ref.

McRoberts KM; Meloni BP; Morgan UM; Marano R; Binz N; Erlandsen SL; Halse SA; Thompson RCA, 1996. Morphological and molecular characterization of Giardia isolated from the straw-necked ibis (Threskiornis spinicollis) in Western Australia. Journal of Parasitology, 82(5):711-718; 52 ref.

Meneses-Marcel A; Olazabal-Manso E; Serrano-Perez H; Gonzalez-Hernandez O; Salinas-Melendez JA, 1994. Frequency of Giardiasis in some species of domestic animals from Villa Clara province, Cuba. Veterinaria-Mexico, 25(4):337-340.

Meyer EA, 1994. Giardia as an organism. Giardia: from molecules to disease., 3-13; 20 ref.

Meyer EA; Jarroll EL, 1980. Giardiasis. American Journal of Epidemiology, 111(1):1-12.

Mintz ED; Hudson-Wragg M; Mshar P; Cartter ML; Hadler JL, 1993. Foodborne giardiasis in a corporate office setting. Journal of Infectious Diseases, 167(1):250-253; 8 ref.

Mohan R, 1993. Evaluation of immunofluorescent and ELISA tests to detect Giardia and Cryptosporidium in birds. Proceedings 1993 Annual Conference Association of Avian Veterinarians, August 31 - September 4, 1993, Nashville, Tennessee., 62-64; 4 ref.

Monis PT; Andrews RH; Mayrhofer G; Ey PL, 1999. Molecular systematics of the parasitic protozoan Giardia intestinalis. Molecular Biology and Evolution, 16(9):1135-1144.

Nash TE, 1997. Antigenic variation in Giardia lamblia and the host's immune response. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 352(1359):1369-1375; 60 ref.

Nesvadba J; Horning B; Nesvadba J Jr; Nesvadba Z, 1982. Giardiasis beim rind. Proceedings of the XIIth World Congress on Diseases of Cattle, Netherlands, World Association for Buiatrics, 1:237-241.

Nieschulz O, 1924. Uber den Bau von Giardia caprae mihi. Archiv Protistenkunde (Jena), 44:278-286.

Nikitin VF; Taichinov UG; Pavlásek I; Kopacka M, 1991. Prevalence of Giardia protozoa in calves. Veterinariya (Moskva), No.6:33-34; 11 ref.

O'Handley RM; Cockwill C; Jelinski M; McAllister TA; Olson ME, 2000. Effects of repeat fenbendazole treatment in dairy calves with giardiosis on cyst excretion, clinical signs and production. Veterinary Parasitology, 89(3):209-218; 36 ref.

O'Handley RM; Cockwill C; McAllister TA; Jelinski M; Morck DW; Olson ME, 1999. Duration of naturally acquired giardiosis and cryptosporidiosis in dairy calves and their association with diarrhea. Journal of the American Veterinary Medical Association, 214(3):391-396; 46 ref.

O'Handley RM; Olson ME; Fraser D; Adams P; Thompson RCA, 2000a. Prevalence and genotypic characterization of Giardia in dairy calves from western Australia and western Canada. Veterinary Parasitology, 90(3):193-200.

O'Handley RM; Olson ME; McAllister TA; Morck DW; Jelinski M; Royan G; Cheng KJ, 1997. Efficacy of fenbendazole for treatment of giardiasis in calves. American Journal of Veterinary Research, 58(4):384-388; 38 ref.

Olson ME; Ceri H; Morck DW, 2000. Giardia vaccination. Parasitology Today, 16(5):213-217.

Olson ME; Guselle NJ; O'Handley RM; Swift ML; McAllister TA; Jelinski MD; Morck DW, 1997. Giardia and Cryptosporidium in dairy calves in British Columbia. Canadian Veterinary Journal, 38(11):703-706; 22 ref.

Olson ME; McAllister TA; Deselliers L; Morck DW; Cheng KJ; Buret AG; Ceri H, 1995. Effects of giardiasis on production in a domestic ruminant (lamb) model. American Journal of Veterinary Research, 56(11):1470-1474; 30 ref.

Olson ME; Thorlakson CL; Deselliers L; Morck DW; McAllister TA, 1997. Giardia and Cryptosporidium in Canadian farm animals. Veterinary Parasitology, 68(4):375-381; 16 ref.

Ozkoc U, 1974. First reported case of parasitic protozoa Giardia caprae in lambs in Turkey. Pendik Veteriner Kontrol ve Arastirma Enstitusu Dergisi (Istanbul), 7(2):223-229.

Padmavathi P; Raddy KR; Emaduddin M; Kulkarni D, 1978. A note about the occurrence of Giardia caprae in lambs. Indian Veterinary Journal, 55(11):917.

Panigrahy B; Elissalde G; Grumbles LC; Hall CF, 1978. Giardia infection in parakeets. Avian Diseases, 22(4):815-818.

Pavlásek I, 1984. First record of Giardia sp. in calves in Czechoslovakia. Folia Parasitologica, 31(3):225-226.

Penpages, 1999. College of Agricultural Sciences, Penn State University, www.penpages.psu.edu.

Pesek L, 1998. Zoonotic diseases - Part IV, Bird to human transmission, Giardia and avian influenza. Winged Wisdom Pet Bird Magazine, www.birdsnways.com/wisdom/ww26eiv.html.

Porter JDH; Gaffney C; Heymann D; Parkin W, 1990. Food-borne outbreak of Giardia lamblia.. American Journal of Public Health, 80(10):1259-1260; 8 ref.

Praagh ADvan; Gavaghan PD; Sykora JL, 1993. Giardia muris cyst inactivation in anaerobic digester sludge. Water Science and Technology, 27(3-4):105-109; 16 ref.

Quigley JDIII; Martin KR; Bemis DA; Potgieter LND; Reinemeyer CR; Rohrbach BW; Dowlen HH; Lamar KC, 1994. Effects of housing and colostrum feeding on the prevalence of selected infectious organisms in feces of Jersey calves. Journal of Dairy Science, 77(10):3124-3131; 22 ref.

Quílez J; Sánchez-Acedo C; Cacho Edel; Clavel A; Causapé AC, 1996. Prevalence of Cryptosporidium and Giardia infections in cattle in Aragón (northeastern Spain). Veterinary Parasitology, 66(3/4):139-146; 38 ref.

Rabbani GH; Islam A, 1994. Giardiasis in humans: populations most at risk and prospects for control. Giardia: from molecules to disease., 217-249; 136 ref.

Reynoldson JA, 1994. New approaches in chemotherapy. Giardia: from molecules to disease., 339-355; 125 ref.

Rigolon LP; Vargas L, 1996. Prevalence of Giardia in dairy cattle in northwest of Paraná-Brazil. Revista UNIMAR, 18(3):617-626; 18 ref.

Rings DM; Rings MB, 1996. Managing Cryptosporidium and Giardia infections in domestic ruminants. Veterinary Medicine, 91(12):1125-1131; 77 ref.

Rosoff JD; Sanders CA; Sonnad SS; Lay PRde; Hadley WK; Vincenzi FF; Yajko DM; O'Hanley PD, 1989. Stool diagnosis of giardiasis using a commercially available enzyme immunoassay to detect Giardia-specific antigen 65 (GSA 65). Journal of Clinical Microbiology, 27(9):1997-2002; 27 ref.

Ruest N; Couture Y; Faubert GM; Girard C, 1997. Morphological changes in the jejunum of calves naturally infected with Giardia spp. and Cryptosporidium spp. Veterinary Parasitology, 69(3/4):177-186; 20 ref.

Ruest N; Faubert GM; Couture Y, 1998. Prevalence and geographical distribution of Giardia spp. and Cryptosporidium spp. in dairy farms in Québec. Canadian Veterinary Journal, 39(11):697-700; 19 ref.

Scholtens RG; New JC; Johnson S, 1982. The nature and treatment of Giardiasis in parakeets. Journal of the American Veterinary Medical Association, 180(2):170-173.

St Jean G; Couture Y; Dubreuil P; Frechette JL, 1987. Diagnosis of Giardia infection in 14 calves. Journal of the American Veterinary Medical Association, 191(7):831-832.

Supperer R, 1952. Uber die Lambliose (Giardiose) des Rindes. Wiener Tierartztliche Monatschrift, 39:26-29.

Suteu E; Cozma V; Bahcivangi S; Mates D; Bozdog C, 1987. Observations on Giardia infections of goats raised in large collective farms. Seminarul. Progrese în terapia si combaterea zoonozelor parazitare. Cluj-Napoca, 6-7 Noviembrie 1987., 170-174; [In: Manifestari Stiintifice de Institutul Agronomic Cluj si Societa de Medicina Veterinara Cluj]; 4 ref.

Suteu E; Rotaru O; Cozma V, 1987. Report of Giardia infection of goats in Romania. Seminarul. Actualitati in patologia animalelor domestice. Cluj-Napoca, 18-19 iunie 1987., 217-222; 8 ref.

Sutherland RJ; Clarkson AR, 1984. Giardiasis in intensively reared Saanen kids. New Zealand Veterinary Journal, 32(3):34-35; 15 ref.

Svobodová V; Chroust K, 1995. Giardiosis and cryptosporidiosis in sheep and goat farming. Veterinárství, 45(9):406-407.

Taminelli V; Eckert J, 1989. Frequency and geographical distribution of Giardia infection of ruminants in Switzerland. Schweizer Archiv für Tierheilkunde, 131(5):251-258; 37 ref.

Taylor MA; Catchpole J; Marshall RN; Green J, 1993. Giardiasis in lambs at pasture. Veterinary Record, 133(6):131-133; 15 ref.

Thompson RCA; Hopkins RM; Holman WL, 2000. Nomenclature and genetic groupings of Giardia infecting mammals. Parasitology Today, 16(5):210-213.

Townson SM; Laqua H; Upcroft P; Boreham PFL; Upcroft JA, 1992. Induction of metronidazole and furazolidone resistance in Giardia.. Transactions of the Royal Society of Tropical Medicine and Hygiene, 86(5):521-522; 9 ref.

Travis BV, 1939. Descriptions of five new species of flagellate protozoa of the genus Giardia. Journal of Parasitology, 25:11-17.

Turner AW; Murnane D, 1932. Giardia in sheep in Victoria, Australia. Australian Journal of Experimental Biological and Medical Science, 10(1):53-56.

Upcroft JA; McDonnell PA; Gallagher AN; Chen N; Upcroft P, 1997. Lethal Giardia from a wild-caught sulphur-crested cockatoo (Cacatua galerita) established in vitro chronically infects mice. Parasitology, 114(5):407-412; 33 ref.

Upcroft JA; Upcroft P, 1993. Drug resistance and Giardia.. Parasitology Today, 9(5):187-190; 60 ref.

Upcroft JA; Upcroft P; Boreham PFL, 1990. Drug resistance in Giardia intestinalis.. International Journal for Parasitology, 20(4):489-496; [Australian Society for Parasitology, Proceedings of the Silver Jubilee Scientific and General Meeting, September 1989]; 39 ref.

Vargas L; Ferreira CS; Carvalheira MS, 1994. Morphometry and cyst counts per gram of faeces (CPG) in ovines in Cidade Gaúcha, Piraná, Brazil. Revista UNIMAR, 16(2):281-287; 8 ref.

Vazquez V; Sotelo J, 1992. The course of seizures after treatment for cerebral cysticercosis. New England Journal of Medicine, 327(10):696-701; 39 ref.

Vílchez QS; Pote L, 1999. Concurrent infections of Cryptosporidium and Giardia in dairy farms, Mississippi State, USA. Revista Cientifica, Facultad de Ciencias Veterinarias, Universidad del Zulia, 9(6):519-523; 27 ref.

Wade SE; Mohammed HO; Schaaf SL, 2000. Prevalence of Giardia sp., Cryptosporidium parvum and Cryptosporidium muris (C. andersoni) in 109 dairy herds in five counties of southeastern New York. Veterinary Parasitology, 93(1):1-11; 44 ref.

Wade SE; Mohammed HO; Schaaf SL, 2000a. Epidemiologic study of Giardia sp. infection in dairy cattle in southeastern New York state. Veterinary Parasitology, 89(1-2):11-21.

Wekhe SN; Olayimka FO, 1999. The role of Agama agama in the transmission of coccidiosis in poultry. Nigerian Veterinary Journal, 20(2):34-36; 6 ref.

Wolfe MS, 1992. Giardiasis. Clinical Microbiology Reviews, 5(1):93-100; 83 ref.

Xiao L; Herd RP, 1994c. Infection patterns of Cryptosporidium and Giardia in calves. Veterinary Parasitology, 55(3):257-262.

Xiao L; Herd RP; McClure KE, 1994. Periparturient rise in the excretion of Giardia sp. cysts and Cryptosporidium parvum oocysts as a source of infection for lambs. Journal of Parasitology, 80(1):55-59; 30 ref.

Xiao L; Saeed K; Herd RP, 1996. Efficacy of albendazole and fenbendazole against Giardia infection in cattle. Veterinary Parasitology, 61:165-170.

Xiao LH; Herd RP; Bowman GL, 1994. Prevalence of Cryptosporidium and Giardia infections on two Ohio pig farms with different management systems. Veterinary Parasitology, 52(3/4):331-336; 27 ref.

Xiao LH; Herd RP; Rings DM, 1993. Concurrent infections of Giardia and Cryptosporidium on two Ohio farms with calf diarrhea. Veterinary Parasitology, 51(1/2):41-48; 37 ref.

Yong TS; Park SJ; Hwang UW; Yang HW; Lee KW; Min DY; Rim HJ; Wang Y; Zheng F, 2000. Genotyping of Giardia lamblia isolates from humans in China and Korea using ribosomal DNA sequences. Journal of Parasitology, 86(4):887-891.

Zimmer JF; Miller JJ; Lindmark DG, 1988. Evaluation of the efficacy of selected commercial disinfectants in inactivating Giardia muris cysts. Journal of the American Animal Hospital Association, 24(4):379-385; 12 ref.

Zizlavsky M; Lukesová D; Limanovsky M, 1998. Prevalence of endoparasitic infections in swine herds and anthelmintic efficacy of flubendazole. Veterinárství, 48(11):467-469; 15 ref.

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