Interdisciplinary Laboratory of Medical Research, Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro / RJ, CEP 21040-360, Brazil
*Address for Correspondence: Maria Fantinatti, Interdisciplinary Laboratory of Medical Research, Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro / RJ, CEP 21040-360, Brazil, Tel: 00-55-21-2562-1034; Email: firstname.lastname@example.org
Dates: Submitted: 29 December 2019; Approved: 06 February 2019; Published: 07 February 2019
How to cite this article: Fantinatti M. Zoonotic potential of Giardia lamblia and control of giardiasis. Insights Vet Sci. 2019; 3: 001-004. DOI: 10.29328/journal.ivs.1001013
Copyright: © 2019 Fantinatti M. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Giardia is the most common pathogenic intestinal flagellate protozoan in the world. The most studied species is Giardia lamblia (syn. Giardia intestinalis, Giardia duodenalis) that infects mammals, including humans. About the other seven species the scientific literature is very scarce and little is known about its characteristics and epidemiological importance. The exception is Giardia muris species that is frequently used in experimental infection to attempt to understand the parasite-host interaction in G. lamblia infection .
The classification of G. lamblia has been made based on the host of origin and morphomolecular characteristics [2,3]. The first divisions in G. lamblia assemblages were performed according to the host specificity from which the isolate originated . This subdivision was corroborated in analyzes of intrinsic characteristics of the parasite, such as antigenic factors, isoenzymes, but mainly through DNA analysis that allows to reaffirm the heterogeneity of G. lamblia [4,5]. Eight assemblages are known, distributed with denominations A to H. Assemblages A and B are potentially zoonotic, as they infect humans and other mammalian hosts, including non-human primates, canids, felines, rabbits, beavers, muskrats, mustelids, rodents, marsupials, wild ruminants and livestock animals. Assemblages C to H are still considered host-specific. Assemblages C and D have already been described in canids; assemblage E was isolated from hoofed animals, as horses, swine, cattle; assemblage F, specific for felines; Assemblage G is found exclusively in mice and rats; Assemblage H was described from pinnipeds feces [1,5].
Although assemblage division and host affinity is maintained to this day, the characterization of G. lamblia assemblages has not yet been fully substantiated. The advancement of genotyping studies has demonstrated that host specificity is not so rigid. Possibly the strains of G. lamblia have undergone an evolutionary process of adaptation to other species hosts or the literature lacked the knowledge about the infective potential of these assemblage. The assemblage C and D, for example, have been reported in felines [6,7] and humans . The assemblage E was described in rabbits , non-human primates , rodents, cats  and humans . Assemblage F was reported in pigs  and cattle .
The G. lamblia transmission occurs by fecal-oral route from ingestion of infective cysts. These cysts, during the passage through the stomach, initiate a process of desencistamento (Ankarklev, 2010) and, in the small intestine, G. lamblia takes the form of trophozoite that fixed in the enterocyte and proliferates by binary division. When carried by the intestinal flow, the trophozoites begin the process of encystment and cysts are released into the already infecting feces . Cysts are evolutionary forms resistant and able to survive in the environment from weeks to months according to the conditions that are exposed [5,16]. Although the water pathway is the main form of contamination and is closely associated with the outbreak’soccurrence , the animal hosts plays a fundamental role in the transmission dynamics of the different assemblages of the parasite, since it favors the maintenance of cysts in the environment. As stray animals do not have fixed residence, they can wander through different places, which can favor the dispersion of infectious cysts. Pets infected with G. lamblia may favor transmission within their home, involving other domestic mammalian and man. Once cysts are released viable for infection, transmission is favored and intensified in crowded places such as nursery, orphanages, asylums, kennels, and poor communities, among others.
The presumptive diagnosis of giardiasis consists in observing the symptoms of infected individual and the definitive diagnosis if by the detection of cysts (or derivatives) and, occasionally, trophozoites in feces. The parasitological examination of feces is still one of the most used methods, although negative false cases can occur, due to the intermittent elimination of this protozoan. Stool samples may present a low number of evolutionary forms which hinders and may mask host parasitic load and even the result of the diagnosis . Diagnosis can also be made by the immunoenzymatic method or by immunochromatography, which may present greater sensitivity and specificity for single sample . The molecular diagnosis by Polymerase Chain Reaction (PCR) for detection of G. lamblia genes specificis considered more sensitive than the parasitological examination and the immunodiagnosis [20-22]. However, especially in poorer countries, where a higher prevalence of giardiasis is expected, due to the high cost of immunological and molecular diagnoses, its use in human and veterinary clinical practice is not yet on routine and the indication if treatment is given by the observation of symptomatology.
In domestic animals, as in humans, the most common symptom is diarrhea, mostly observed in puppies. Many individuals may be asymptomatic. G. lamblia research is more frequent among economically important animals such as cattle, sheep, pigs and horses, as the infection may have an impact on animal weight gain . In these animals the assemblages A, B and E that too have already been described in humans are expected. In addition, in farm environments the contact between different animal species may favor the occurrence of complex zoonotic transmission networks.
Another animals group that has epidemiological importance in giardiasis transmission are domestic animals, such as dogs and cats. The interest in acquisition of these animals has grown in the last century and it is common the adoption of street animals which do not have veterinary care. In addition, we have observed a process of increasing humanization of pets, which brings them closer to human interaction and favors the transmission of anthropozoonotic and zooanthroponotic diseases . It is often reported in the literature genotypes of G. lamblia with anthropozoonotic potential (A and B) circulating in dogs and cats [25,26].
In this context, control actions of giardiasis should consider the potential hosts involved in zoonotic cycles in order to reduce the elimination and circulation of the etiological agent and to stop the transmission of the disease. In developing countries, when control measures are in place, they are often directed to human treatment and water quality control and no measures are directed at animals. Thus, for the effective control of giardiasis, basic sanitation is a priority, but it must be accompanied by health education strategies, to provide knowledge about self-prevention, and treatment of humans and too of animals infected by G. lamblia.
- Cacciò SM, Lalle M, Svärd SG. Host specificity in the Giardia duodenalis species complex. Infect Genet Evol. 2018; 66: 335-345. Ref.: https://goo.gl/w7jr26
- Monis PT, Andrews RH, Mayrhofer G, Ey PL. Molecular systematics of the parasitic protozoan Giardia intestinalis. Mol Biol Evol. 1999; 16: 1135-1144. Ref.: https://goo.gl/U9C2mg
- Thompson RC, Hopkins RM, Homan WL. Nomenclature and genetic groupings of Giardia infecting mammals. Parasitol Today. 2000; 16: 210-213. Ref.: https://goo.gl/Jhp37e
- Adam RD. Biology of Giardia lamblia. Clin Microbiol Rev. 2001; 14: 447-475. Ref.: https://goo.gl/U37gnN
- Feng Y, Xiao L. Zoonotic potential and molecular epidemiology of Giardia species and giardiasis. Clin Microbiol Rev. 2011; 24: 110-140. Ref.: https://goo.gl/iMWzi7
- Palmer CS, Traub RJ, Robertson ID, Devlin G, Rees R, et al. Determining the zoonotic significance of Giardia and Cryptosporidium in Australian dogs and cats. Vet. Parasitol. 2008; 154: 142-147. Ref.: https://goo.gl/nKavAa
- Read CM, Monis PT, Thompson RC. Discrimination of all genotypes of Giardia duodenalis at the glutamate dehydrogenase locus using PCR-RFLP. Infect Genet Evol. 2004; 4: 125-130. Ref.: https://goo.gl/ubF76T
- Traub RJ, Inpankaew T, Reid SA, Sutthikornchai C, Sukthana Y, et al. Transmission cycles of Giardia duodenalis in dogs and humans in Temple communities in Bangkok--a critical evaluation of its prevalence using three diagnostic tests in the field in the absence of a gold standard. Acta Trop. 2009; 111: 125-132. Ref.: https://goo.gl/TwXpZj
- Qi M, Xi J, Li J, Wang H, Ning C, et al. Prevalence of Zoonotic Giardia duodenalis Assemblage B and First Identification of Assemblage E in Rabbit Fecal Samples Isolates from Central China. J Eukaryot Microbiol. 2015; 62: 810-814. Ref.: https://goo.gl/9U12xU
- Du SZ, Zhao GH, Shao JF, Fang YQ, Tian GR, et al. Cryptosporidiumspp, Giardia intestinalis, and Enterocytozoonbieneusi in captive non-human primates in Qinling Mountains. Korean J Parasitol. 2015; 53: 395-402. Ref.: https://goo.gl/ncRDh3
- Lebbad M, Mattsson JG, Christensson B, Ljungström B, Backhans A, et al. From mouse to moose: multilocus genotyping of Giardia isolates from various animal species. Vet Parasitol. 2010; 168: 231-239. Ref.: https://goo.gl/4ZSJUC
- Fantinatti M, Bello AR, Fernandes O, Da-Cruz AM. Identification of Giardia lamblia assemblage E in humans points to a new anthropozoonotic cycle. J Infect Dis. 2016; 214: 1256-1259. Ref.: https://goo.gl/E5v1G1
- Armson A, Yang R, Thompson J, Johnson J, Reid S, et al. Giardia genotypes in pigs in Western Australia: prevalence and association with diarrhea. Exp Parasitol. 2009; 121: 381-383. Ref.: https://goo.gl/B3aW5u
- Cardona GA, de Lucio A, Bailo B, Cano L, de Fuentes I2, et al. Unexpected finding of feline-specific Giardia duodenalisassemblage F and Cryptosporidium felis in asymptomatic adult cattle in Northern Spain. Vet Parasitol.2015; 209:258-263. Ref.: https://goo.gl/pL9qvC
- Carranza PG, Lujan HD. New insights regarding the biology of Giardia lamblia. Microbes Infect. 2010; 12: 71-80. Ref.: https://goo.gl/CRL7NG
- Travaillé E, La Carbona S, Aubert D, Guyot K, Gargala G, et al. Development of qRT-PCR method to assess viability of Giardia intestinalis cysts, and Cryptosporidium spp. and Toxoplasma gondii oocysts. Food Control. 2016; 59: 359-365. Ref.: https://goo.gl/Y2vGaN
- Baldursson S, Karanis P. Waterborne transmission of protozoan parasites: review of worldwide outbreaks - an update 2004-2010. Water Res. 2011; 45: 6603-6614. Ref.: https://goo.gl/kMGYxx
- Hawash Y. DNA extraction from protozoan oocysts/cysts in feces for diagnostic PCR. Korean J Parasitol. 2014; 52: 263-271. Ref.: https://goo.gl/7Cyy19
- Vidal AM, Catapani WR. Enzyme-linked immunosorbent assay (ELISA) immunoassaying versus microscopy: advantages and drawbacks for diagnosing giardiasis. Sao Paulo Med J. 2005; 123: 282-285. Ref.: https://goo.gl/MEgXcT
- Schuurman T, Lankamp P, van Belkum A, Kooistra-Smid M, van Zwet A. Comparison of microscopy, real-time PCR and a rapid immunoassay for the detection of Giardia lamblia in human stool specimens. Clin Microbiol Infect. 2007; 13: 1186-1191. Ref.: https://goo.gl/T63z7j
- Calderaro A, Gorrini C, Montecchini S, Peruzzi S, Piccolo G, et a. Evaluation of a real-time polymerase chain reaction assay for the laboratory diagnosis of giardiasis. Diagn Microbiol Infect Dis. 2010; 66: 261-267. Ref.: https://goo.gl/DFb8sp
- Elsafi SH, Al-Maqati TN, Hussein MI, Adam AA, Hassan MM, et al. Comparison of microscopy, rapid immunoassay, and molecular techniques for the detection of Giardia lamblia and Cryptosporidium parvum. Parasitol Res. 2013; 112: 1641-1646. Ref.: https://goo.gl/7oL3JX
- Geurden T, Vercruysse J, Claerebout E. Is Giardia a significant pathogen in production animals? Exp Parasitol. 2010; 124:98-106. Ref.: https://goo.gl/g4eBFQ
- Walsh F. Human-animal bonds I: the relational significance of companion animals. Fam Process. 2009; 48: 462–480. Ref.: https://goo.gl/mL2HXq
- Lalle M, Jimenez-Cardosa E, Cacciò SM, Pozio E. Genotyping of Giardia duodenalis from human and animal samples from Brazil using beta-giardin gene: a phylogenetic analysis. Acta Trop. 2007; 102: 10-19. Ref.: https://goo.gl/Ej5tRQ
- Fantinatti M, Caseca AC, Bello AR, Fernandes O, Da-Cruz AM. The presence of Giardia lamblia assemblage A in dogs suggests an anthropozoonotic cycle of the parasite in Rio de Janeiro, Brazil. Infect Genet Evol. 2018; 65: 265-269. Ref.: https://goo.gl/633k1t
- Ey PL, Bruderer T, Wehrli C, Köhler P. Comparison of genetic groups determined by molecular and immunological analyses of Giardia isolated from animals and humans in Switzerland and Australia. Parasitol Res.1996; 82: 52-60. Ref.: https://goo.gl/2rB3c7
- Hopkins RM, Meloni BP, Groth DM, Wetherall JD, Reynoldson JA, et al. Ribosomal RNA sequencing reveals differences between the genotypes of Giardia isolates recovered from humans and dogs living in the same locality. J Parasitol.1997; 83: 44-51. Ref.: https://goo.gl/qPZKF8
- Lasek-Nesselquist E, Welch DM, Sogin ML. The identification of a new Giardia duodenalis assemblage in marine vertebrates and a preliminary analysis of G. duodenalis population biology in marine systems. Int J Parasitol. 2010; 40: 1063-1074. Ref.: https://goo.gl/ZE5zMS
- Monis PT, Andrews RH, Mayrhofer G, Mackrill J, Kulda J, et al. Novel lineages of Giardia intestinalis identified by genetic analysis of organisms isolated from dogs in Australia. Parasitology.1998; 116: 7-19. Ref.: https://goo.gl/J5VbSj