Giardiasis as zoonosis: between proof of principle and paradigm in the Northwestern region of São Paulo State, Brazil

OBJECTIVE: In order to evaluate the potential zoonotic transmission of Giardia duodenalis, isolates from humans and dogs in the Northwestern region of the São Paulo State, Brazil were characterized based on the β-giardin gene. METHODS: The samples were analyzed by sequencing of the Nested-PCR products. RESULTS: The A1 and A2 subgenotypes were detected in human and dogs. Cysts of assemblage B, C and D have not been found in any isolates studied. CONCLUSIONS: These results are consistent with the view that giardiasis in the largest endemic region of the Brazil should not be seen as a single entity.

Detection of the [Tim] gene of sheep Giardia using [Tim] Gene primers of Giardia with human origin

Giardiasis is an important human parasitic disease. Giardia is a genus composed of binuclear flagellate protozoa. Giardia duodenalis is a parasitic species for a wide range of vertebrates, including humans. Heterogeneity in G. duodenalis has been shown by serological, biochemical, and molecular analysis. In the present study, the possible genetic similarity between Giardia in sheep and humansand their probable zoonosis was investigated. Direct examination and formalin ether concentration technique were performed on the contents and tissues of sheep intestines. The gradient sucrose method was applied to collect and purify cysts, and DNA extraction was performed by the phenol-chloroform method. Only very small amounts of DNA could be extracted after repeated freezing, thawing and suspension with lysis buffer, after which polymerase chain reaction [PCR] was performed for DNA amplification by primers that were designed for Giardia of human origin. The gene, [triose phosphate isomerase] [tim or tpi], was selected as the molecular marker and two sets of primers [PM290, PM924] were used. We examined 308 sheep stool samples in our study, including 21 positive samples. Cultures for Giardia were negative. Three sheep isolates were determined by a 290 base pair [bp] amplicon that were similar to certain human types. The similarity of the sheep and human genomic characters of Giardia implies the possibility that there is transmission of these protozoa between humans and sheep

Classic and molecular study of Giardia duodenalis in children from a daycare center in the region of Presidente Prudente, São Paulo, Brazil / Estudo clássico e molecular de Giardia duodenalis em crianças atendidas em uma creche na região de Presidente Prudente, São Paulo, Brasil

Epidemiological studies on giardiasis by using molecular techniques such as RAPD (Randomly Amplified Polymorphic DNA) may give information on factors related to the transmission of Giardia duodenalis. The aim of this work was to assess the epidemiology of G. duodenalis in 101 children attended at a daycare center in Presidente Bernardes, SP, Brazil. After parasitological examinations in feces samples, 15 children presented cysts of G. duodenalis. Their respective parents, brothers and pets, besides the daycare center workers, also had their feces submitted to parasitological analysis. Seven mothers and nine brothers also presented G. duodenalis cysts, while fathers, daycare workers and pets (dogs) did not presented the parasite. Besides the 15 cases with G. duodenalis, other 23 children presented other enteroparasites (Entamoeba coli, Endolimax nana, Enterobius vermicularis, Ascaris lumbricoides and Trichuris trichiura). Samples of G. duodenalis cysts from children and their relatives were submitted to molecular typing by RAPD after genomic DNA extraction and amplification of a fragment of the 18S rDNA region by PCR. After examining 31 isolates of G. duodenalis (children and their respective mothers and brothers), it was concluded that the parasite transmission occurred in children, probably during daily cohabitation at the daycare center, but not at home among their relatives or pets.

Estudos epidemiológicos sobre giardíase por técnicas moleculares como a RAPD (Amplificação aleatória do DNA polimórfico) podem contribuir para o entendimento de fatores relacionados à transmissão de Giardia duodenalis. O objetivo desse trabalho foi estudar a epidemiologia de G. duodenalis em 101 crianças atendidas em uma creche em Presidente Bernardes, SP, Brasil. Após exames parasitológicos em amostras de fezes, 15 crianças apresentaram cistos de G. duodenalis. Seus respectivos pais, irmãos e animais domésticos, além dos funcionários da creche, foram submetidos a exames parasitológicos de fezes. Destes, sete mães e nove irmãos apresentaram G. duodenalis, enquanto os pais, funcionários da creche e animais de estimação (cães) não apresentaram o parasita. Além dos 15 casos com G. duodenalis, outras 23 crianças apresentaram outros enteroparasitas (Entamoeba coli, Endolimax nana, Enterobius vermicularis, Ascaris lumbricoides e Trichuris trichiura). As amostras contendo cistos de G. duodenalis das crianças e de seus parentes foram submetidas à análise molecular por RAPD após extração do DNA genômico e amplificação de um fragmento de uma região do rDNA 18S por PCR. Entre os 31 isolados de G. duodenalis (crianças e suas respectivas mães e irmãos), concluiu-se que a transmissão dos parasitas ocorreu entre as crianças, provavelmente durante seu convívio na creche, mas não foi decorrente do convívio familiar ou animais de estimação.

Occurrence of Giardia cysts and Cryptosporidium oocysts in the Temuan Orang Asli (aborigine) River System.

A survey of the river water frequently used by the Temuan Orang Asli (aborigine) indicated that 66.7% of the river water samples were Giardia cyst positive and 5.6% were Cryptosporidium oocyst positive. Although Giardia cysts were detected in samples from all the sites (e.g. upstream, midstream, and downstream), Cryptosporidium was only present in one river water sample taken from downstream from a village. The only sample of upstream water which contained Giardia cysts had a concentration of 0.7 cysts/l. All samples taken from midstream contained cysts with a mean concentration of 9.8 +/- 6.6 cysts/l (range = 1-20 cysts/l). Eighty-three point three percent of the samples collected from downstream contained cysts and 16.7% had oocysts. The average concentration of cysts was 12.9 +/- 16.4 cysts/l (range = 0-44 cysts/l), whereas the oocyst concentration was 0.4 oocysts/l. All river samples tested positive for the presence of E. coli, indicating fecal contamination. The results of this study imply that the river system is contaminated with fecal-oral transmitted parasites. The river water, used by the Orang Asli, is a probable route for Giardia and Cryptosporidium transmission in this community. Long term strategies, incorporating health education regarding personal hygiene, and provision of toilets and the importance of their proper usage, need to be embraced by this community in order to control the spread of these parasites.

Influence of temperature and salinity on the viability and infectivity of giardia lamblia and cryptosporidia parvum

The present work was designed to assess the effect of different degrees of temperature and salinity on the viability and infectivity of G. Lamblia and C. parvum at different storage times. The results revealed that boiling of protozoa for one minute minimized their viability to less than 1% and rendered them noninfectious, while the exposure to 4C and -4C up to seven days preserved their viability and infectivity. Whereas, it was found that salinity was effective at a high concentration [50 ppt] for a long storage time at lower concentrations

Impacto de la dieta sobre la inducción de infección con quistes de Giardia lamblia en ratas Sprague-Dawley / Impact of diet on the induction of infection with Giardia lamblia cysts in Sprague-Dawley rats

OBJECTIVE: To assess the effect of malnutrition on the development of giardiasis in Sprague-Dawley rats, using different inoculum sizes of Giardia lamblia cysts. MATERIAL AND METHODS: An experimental study was conducted between 1995 and 1999 at Centro de Investigación, Alimentación y Desarrollo (Center for Research, Food, and Development), in Hermosillo, Sonora, Mexico. The study population consisted of two groups of six to eight experimental units that were fed two different diets and inoculated five different concentrations of Giardia lamblia cysts. Data were collected on excretion of cysts, weight gain, food intake, bowel contents, and macro and microscopic lesions in the intestinal mucosa. Statistical analysis consisted of analysis of variance and residuals. RESULTS: Animals fed with a diet meeting nutritional requirements required an infecting inoculum of 60 cysts, while malnourished rats required only six cysts to develop mucosal lesions. CONCLUSIONS: Weight gain monitored during ten days was not a good indicator of Giardia lamblia infection. Infection depended on cyst inoculum size as well as on the nutritional status of the tested animals.

Distancia filogenética de aislados de Giardia intestinalis de niños sintomáticos y asintomáticos / Phylogenetic distance between Giardia intestinalis isolates from symptomatic and asymptomatic children

The purpose of the present investigation, was to analyze the sequences of 16S ribosomal genes partially amplified from 17 isolated Giardia intestinalis obtained from faces of 13 children with intestinal pathology and four symptoms-free children with intestinal pathology. Analysis was made also with Giardia Portland-I and four Giardias isolated from dogs. Children ages in both groups ranged from six to twelve years. Genomic DNA was isolated using the phenol-chloroform-isoamyl alcohol technique, and partial amplification of 16S rRNA ribosomal gene was carried out by the Polymerase Chain Reaction. Sequences of rDNA were compared with Portland-I by using CLUSTAL-W (1.81) and PHYLIP (3.6) software in order to determine phylogenic associations. Our results showed that only one isolate from symptoms-free children and three from the symptomatic children were associated with Portland I. The other isolated Giardias were associated between them and with two samples obtained from dogs that are phylogenetically distant from Portland-I. Two isolates from dog constituted a different group. These results suggest a zoonotic infection and presence of symptoms in children from the present investigation; probably it was associated with host or special characteristics of Giardia strains. The last two situations have a special epidemiological and public health interest.