Abstract
In this study, we proposed to verify the most suitable murine experimental model for studying human giardiasis. In total 150 animals were used. Fifty mice (Mus musculus) from each lineage (Swiss, Balb/c and C57BL/6), 25 females and 25 males, were divided into 5 groups with 5 animals each, according to the lineage/sex. Three groups were infected with 104 cysts of Giardia duodenalis of assemblage BIV and 2 negative control groups. The animals were followed and evaluated for 15 days after receiving the inoculum. The clinical parameters evaluated were body weight, water and feed intake, excretion, appearance of fur and feces, elimination of Giardia spp cysts and behavioral assessment. The clinical parameters of the groups infected with G. duodenalis were compared with the non-infected groups within their own lineage/sex. In the 15 days of monitoring, only the male Swiss mice presented differences in these parameters. The infected animals consumed more feed, water and eliminated more excreta than the non-infected group. There was no difference in the general average of the weight of the animals or in the behavioral assessment in any group. Only the infected male Swiss mice eliminated G. duodenalis cysts in the feces, which was confirmed by the molecular diagnosis and by observing the presence of trophozoites in the intestinal mucosa. The results demonstrate that the most suitable animal model for the study of human giardiasis is the male Swiss mice, since it was the only one capable of developing infection by G. duodenalis cysts.
Highlights
The etiologic agent of giardiasis, Giardia duodenalis is one of the most prevalent protozoa in the human gastrointestinal tract (Colli et al, 2015; Hooshyar et al, 2019), and the most associated with cases of infectious diarrhea (Cock et al, 2020), which are an important cause of morbimortality in children under five years old (Baker & Alonso, 2018)
It is concluded that male Swiss (Mus musculus) is the most suitable experimental model for the study of human giardiasis assemblage BIV, as it is the only lineage, compared with the other lineages studied, capable of becoming infected and eliminating G. duodenalis cysts in the feces
Significant alterations in clinical parameters were observed in infected animals when compared with uninfected animals, signaling that important mucosal lesions, similar to the lesions present in human infection, may be occurring
Summary
The etiologic agent of giardiasis, Giardia duodenalis (synonyms: Giardia lamblia and Giardia intestinalis) is one of the most prevalent protozoa in the human gastrointestinal tract (Colli et al, 2015; Hooshyar et al, 2019), and the most associated with cases of infectious diarrhea (Cock et al, 2020), which are an important cause of morbimortality in children under five years old (Baker & Alonso, 2018). Giardiasis has a global distribution, reaching an average of between 2 and 7% of the population in developed countries, and might reach 30% in developing or underdeveloped countries (Fantinatti et al, 2016), totaling more than 200 million cases diagnosed by year (Hooshyar et al, 2019). It can be asymptomatic or symptomatic with chronic diarrhea and intestinal malabsorption, leading to disorders in growth and intelectual/cognitive development in children (Lima et al, 2019). In the southern region of Brazil, there is a predominance of the assemblage BIV (Colli et al, 2015)
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