Eliminação de Giardia muris em modelo experimental murino naturalmente infectado: Tratamento complementar

Objetivo: Neste estudo foi proposto um tratamento complementar para giardíase murina comparando Chá preto (CPR) (Camellia sinensis) com Metronidazol (MT), Fembendazol (FB) e Metronidazol em associação com Sulfadimetoxina (MtS) em camundongos Swiss machos (30) divididos em seis grupos (CPR, MT, FB/MT, MtS, CPR/MtS e Controle não Tratado - C+) com cinco animais cada. Metodologia: O tratamento foi via intragástrica, por 7 dias 1x/dia e o grupo C+ recebeu apenas água. Os experimentos foram conduzidos de forma cega, controlada, randomizada e repetido uma vez com mesmo número de animais. Parâmetros clínicos (peso, consumo de água, ração e eliminação de excretas) também foram avaliados. Resultados: Os animais dos grupos CPR/MtS e MtS e do grupo CPR apresentaram resultados parasitológicos e molecular negativos para G. muris no 5º e 7º dia após início do tratamento, respectivamente. Os animais dos grupos FB/MT, MT e C+ continuaram a eliminar cistos após o término do tratamento. Os animais do grupo C+ apresentaram perda de peso significativa em relação aos animais dos demais grupos e consumiram menor quantidade de ração (p=0,0001) em relação aos animais dos grupos CPR/MtS, FB/MT e MT. Conclusão: O tratamento complementar com chá preto isolado ou associado ao MtS foi eficaz para eliminar G. muris, sendo uma estratégia promissora para modelo experimental murino. Os animais não tratados que mantiveram alta carga parasitária apresentaram alterações significativas nos parâmetros clínicos, mostrando a importância de eliminar infecção pré-existente e aumentar a confiabilidade dos resultados dos experimentos que utilizam esses animais.

Ferric sulphate flocculation as a concentration method for Giardia and Cryptosporidium in filter backwash water

Filter backwash water (FBW) is a prominent residue from water treatment plants (WTPs) that is often disposed into water bodies or recycled within the WTP without due disinfection. FBW usually contains particles within a size range that includes pathogenic protozoa, as the infective forms of Giardia and Cryptosporidium, parasites responsible for waterborne diseases outbreaks. Quantifying (oo)cysts is essential for addressing this matter, as it might assist research on giardiasis and cryptosporidiosis epidemiology, as well as shed light onto disinfection technologies for FBW. However, (oo)cyst recovery from FBW and other complex matrices still lacks a standard protocol and entails specialized professionals and expensive material. Seeking to provide insight in a reduced-cost recovery method, this study analysed the recovery efficiency (RE) obtained by acid flocculation with ferric sulphate, a common coagulant, on bench-scale simulated FBW. Steps included concentration by flocculation, centrifugation, and quantification by immunofluorescence. Although recovery was sufficient for Cryptosporidium parvum (40.59%), Method 1623.1 recommendations were not reached for Giardia muris (1.76%). Coefficients of variation obtained for both organisms were not satisfactory, highlighting the variability to which environmental matrices are subjected and why defining a methodology for (oo)cyst recovery in WTP residues is important.

Evaluation of Therapeutic Approaches for the Treatment of Spironucleus muris in Mice

Spironucleus muris is an intestinal protozoal pathogen that can infect various species of rodents. The infection can have a wide range of clinical presentations, from no signs of disease to death. In addition, this pathogen can adversely affect research results, especially immunologic and gastrointestinal studies. For these reasons, institutions may exclude Spironucleus muris. However, despite rigorous efforts to keep this pathogen out, it can be common in rodent colonies. The current recommendedapproach to eradicating this pathogen is by testing and culling positive animals. A similar organism, Giardia muris, has been effectively eliminated by using chemotherapeutics. Therefore, the objective of this study was to determine whether S. muris is also susceptible to chemotherapeutics. Naturally infected mice were randomized to treatment groups after confirmation of positive infection via PCR. Mice received either metronidazole, fenbendazole, a combination of metronidazole-fenbendazole,or acidified water (control) treatments for a period of 4 wk. Each week fecal testing of S. muris was performed via PCR to evaluate the effectiveness of the treatments. At the end of the 4 wk period, mice were euthanized via CO2inhalation and segments of the proximal gastrointestinal tract were submitted for histopathologic analysis. Treatment with metronidazole or fenbendazole alone or in combination, failed to clear S. muris infected mice. After 4 wk of treatment, none of the mice given fenbendazole via sucralose medicated gel were positive by either PCR or histopathology; however, this finding is most likelydue to intermittent shedding rather than chemotherapeutic success. Therefore, the recommendation remains to test-and-cull or rederive mice as necessary to eliminate S. muris from laboratory animal facilities.

The compact genome of Giardia muris reveals important steps in the evolution of intestinal protozoan parasites

Diplomonad parasites of the genus Giardia have adapted to colonizing different hosts, most notably the intestinal tract of mammals. The human-pathogenic Giardia species, Giardia intestinalis, has been extensively studied at the genome and gene expression level, but no such information is available for other Giardia species. Comparative data would be particularly valuable for Giardia muris, which colonizes mice and is commonly used as a prototypic in vivo model for investigating host responses to intestinal parasitic infection. Here we report the draft-genome of G. muris. We discovered a highly streamlined genome, amongst the most densely encoded ever described for a nuclear eukaryotic genome. G. muris and G. intestinalis share many known or predicted virulence factors, including cysteine proteases and a large repertoire of cysteine-rich surface proteins involved in antigenic variation. Different to G. intestinalis, G. muris maintains tandem arrays of pseudogenized surface antigens at the telomeres, whereas intact surface antigens are present centrally in the chromosomes. The two classes of surface antigens engage in genetic exchange. Reconstruction of metabolic pathways from the G. muris genome suggest significant metabolic differences to G. intestinalis. Additionally, G. muris encodes proteins that might be used to modulate the prokaryotic microbiota. The responsible genes have been introduced in the Giardia genus via lateral gene transfer from prokaryotic sources. Our findings point to important evolutionary steps in the Giardia genus as it adapted to different hosts and it provides a powerful foundation for mechanistic exploration of host–pathogen interaction in the G. muris–mouse pathosystem.