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Revista do Instituto de Medicina Tropical de São Paulo

On-line version ISSN 1678-9946

Rev. Inst. Med. trop. S. Paulo vol.55 no.1 São Paulo Jan./Feb. 2013 



Prevalence and risk factors for intestinal protozoa infection in elderly residents at Long Term Residency Institutions in Southeastern Brazil


Prevalência e fatores de risco para infecção por protozoários intestinais em idosos residentes nas Instituições de Longa Permanência no Sudeste do Brasil



Katymilla Guimarães GirottoI; Daliane Faria GramaI; Maria Júlia Rodrigues da CunhaI; Elaine Silva Marques FariaI; Jean Ezequiel LimongiII; Rogério de Melo Costa PintoIII; Márcia Cristina CuryI

IInstituto de Ciências Biomédicas, Laboratório de Parasitologia, Universidade Federal de Uberlândia, Minas Gerais, Brazil
IIInstituto de Ciências Biomédicas, Laboratório de Biologia Molecular, Universidade Federal de Uberlândia, Minas Gerais, Brazil
IIIFaculdade de Matemática, Universidade Federal de Uberlândia, Minas Gerais, Brazil

Correspondence to




This study determined the prevalence of intestinal protozoa in Long Term Residency Institutions for the Elderly (ILPI) in elders, nurses and food handlers, identifying the risk factors associated with the infections. Stool samples taken from the elderly (n = 293), nurses (63) and food handlers (19) were studied. Questionnaires were used with questions related to sociodemographic variables, health, behavior and health characteristics. Stool samples were examined using the techniques of Faust and Ziehl Neelsen, and the prevalence of G. duodenalis, Cryptosporidium spp., E. histolytica/dispar in the elderly was 4.0%, 1.0% and 0.3% respectively. Nurses and food handlers showed 4.8% and 5.2% positivity only for G. duodenalis, respectively. The origin of the individuals and contact with domestic animals has been associated with infection by G. duodenalis in the elderly, and contact with domestic animals was considered a risk factor for infection. The last stool examinations were related to Cryptosporidium spp.. None of the variables were associated with E. histolytica/dispar. The frequency of hand washing was significantly associated with G. duodenalis among nurses. The frequency of positive samples of G. duodenalis, Cryptosporidium spp., E. histolytica/dispar showed that ILPIs environments are conducive to this occurring due to contact between the elderly, nurses and food handlers, which are often poorly trained in hygiene procedures and food handling.

Keywords: Elderly; Intestinal protozoa; Risk factors.


Este estudo determinou a prevalência de protozoários intestinais em Instituições de Longa Permanência para Idosos (ILPI), enfermeiros, manipuladores de alimentos identificando fatores de risco associados às infecções. Amostras de fezes de idosos (n = 293), enfermeiros (63), manipuladores de alimentos (19) foram estudadas. Foram aplicados questionários relacionados a variáveis sociodemográficas, de higiene, comportamento e características de saúde. As amostras de fezes foram examinadas pelas técnicas de Faust e Ziehl Neelsen e a prevalência de G. duodenalis, Cryptosporidium spp., E.histolytica/dispar nos idosos foi de 4,0%, 1,0% e 0,3%, respectivamente. Enfermeiros e manipuladores de alimentos apresentaram 4,8% e 5,2% de positividade apenas para G. duodenalis, respectivamente. A origem dos indivíduos, o contato com animais domésticos foram associados à infecção por G. duodenalis nos idosos, sendo que o contato com animais domésticos foi considerado um fator de risco para a infecção, o tempo do último exame coproparasitológico foi relacionado a Cryptosporidium spp.. Nenhuma das variáveis apresentaram associação com E. histolytica/dispar. A frequência da lavagem das mãos foi associada significativamente com G. duodenalis entre enfermeiros. As frequências de amostras positivas para G. duodenalis, Cryptosporidium spp., E. histolytica/dispar demonstram que ILPIs são ambientes propícios para esta ocorrência devido ao contato entre idosos, enfermeiros, manipuladores de alimentos, que muitas vezes são mal treinados em procedimentos de higiene e manipulação de alimentos.




Enteric parasitosis in the elderly can acquire a serious nature due to the ageing of the immune system leading to morphophysiological changes in these individuals8,28.

The intestinal protozoa G. duodenalis, Cryptosporidium spp. and E.histolytica/dispar are important for the elderly because they are borne in water and food and are associated with unreliable hygiene habits. G. duodenalis and Cryptosporidium spp. are also important in public health due to their zoonotic potential25. The prevalence of these protozoa is related to human clusters, therefore, nursing homes became important sites for the research of these organisms6.

Despite the ageing of the world's population and the presence of these protozoa in several localities, there are few reports on their prevalence and epidemiological aspects in the elderly population. Therefore studies are needed to improve the quality of life of this section of the human population. This study determined the prevalence of intestinal protozoa in elderly residents and workers at Long Term Residency Institutions for the Elderly (ILPI), investigating the risk factors for infection in these individuals.



This study was characterized as sectional and was conducted between December 2009 and October 2010 in the 16 ILPI in the municipalities of Araguari, Monte Alegre de Minas, Tupaciguara and Uberlândia, in the State of Minas Gerais, Brazil.

The population studied composed of 293 elderly residents in those ILPIs of both genders, with an age range of between 60 and 106 years old. 63 nurses and 19 food handlers from the same institutions were also evaluated.

Stool samples were collected and stored in identified collector flasks. These flasks were transported to the Parasitology Laboratory of the Federal University of Uberlândia (UFU), stored under refrigeration at 4 ºC and processed within 24 hours of the collection time. Due to the intermittent pattern of G. duodenalis and to increase the reliability of the results, three stool samples were collected from each individual on alternate days5.

Each sample was divided in two, and the first portion was used in the search for G. duodenalis and E.histolytica/dispar cysts using 33% of Zinc Sulfate Centrifugal Flotation in the Method10, performed with fresh feces. In the second portion the three samplings were pooled together and preserved in 10% formalin, they were used in the search for Cryptosporidium spp. oocysts by examining the concentration in formalin ether22 and Ziehl Neelsen staining13. Three slides were made per individual and examined by two trained professionals.

Four questionnaires were prepared, one related to the ILPI; another for the elderly; the third for the nurses and the fourth for the food handlers.

The data were analyzed by EPI INFO 3.3.2 software (CDC, Atlanta, GA, USA). The Chi-square test (X2, α = 5%) was used in the comparison of two proportions. The ANOVA test was used for the comparison between the groups and the variables in which the average of the results were used. The Mann-Whitney test was used when the data did not present a normal distribution. The odds ratio (OR) with a confidence interval (CI) of 95%16 was used to evaluate the possible risk factors associated with infection of the intestinal protozoa. At frequencies lower than five, the statistical significance was calculated using simulation by the Monte Carlo method with 2,000 samplings being studied29.

The study was approved by the Ethical Research Committee - CEP, under the CEP/UFU: 031/10 Protocol.



Out of the total number of samples taken from the elderly, 28 (9.5%) tested positive for intestinal protozoa, distributed as 10 (35.7%) for G. duodenalis, three (10.7%) for Cryptosporidium spp., nine (32.2%) for Entamoeba coli and two (7.1%) for Endolimax nana. Four of the elders (14.3%) presented bi-parasitism, with two (50.0%) being positive for G. duodenalis and E. coli; one (25.0%) for E. nana and E.coli and one (25.0%) for E.histolytica/dispar and E. coli.

Regarding the positivity of G. duodenalis (n = 12) among the sociodemographic, hygienic and behavioral variables (Table 1), the origin (OR = 1.70 (0.30-7.75); p = 0.03) and contact with domestic animals, all were statistically significant with exception of the last which was considered a risk factor for infection (OR = 15.34 (1.66-114.32); p = 0.02). The other variables related to health care had no relationship with this protozoon.

Three elders (1.0%) presented single parasitism with Cryptosporidium spp.. Among the analyzed variables, only the time of completion of the last coproparasitological examination was statistically significant (p = 0.04) (Table 2).

Only one elderly presented positivity for E.histolytica/dispar, however without symptoms. The analyzed variables were not significant (p > 0.05).

Three nurses (4.8%) were tested positive for G. duodenalis and sociodemographic, behavior and associated factors with elderly health care, were not significant (p > 0.05). The frequency of hand washing during the day, about 36.66 ± 5.77 times (p = 0.02), was the only variable related to hygiene that presented statistical significance with undefined odds ratio (OR) (Table 3).

One (5.2%) out of the 19 food handlers presented parasitism for G. duodenalis. No statistically significant difference among the analyzed variables was observed (p > 0.05).



The prevalence of G. duodenalis in the elderly was higher than observed in previous studies1,2,3,20,23 and lower than observed in other studies12,14,27. The difference in the results can be associated with the number of samples taken, methodology, environmental differences and host immunological conditions. Researchers claim that there is a lower risk of G. duodenalis infection with the advancement of age due to cellular and humoral immune responses that would protect these individuals from re-infection15,19.

The prevalence observed for Cryptosporidium spp. in the elderly was lower than the ones presented on research7,21,24. Factors affecting the survival and the number of oocysts present in the environment, such as rain or agricultural practices, can interfere with differences in the prevalence of that protozoan. The prevalence of intestinal protozoa is associated with the combination of multiple variables that determine the interaction between the parasite, the host and the environment18. In addition, the migration of people and the presence of animals as reservoirs, linked to poor sanitary conditions, are factors that contribute to contamination through drinking water which is the main route of transmission of this protozoan24.

The prevalence of E.histolytica/dispar was lower than the previous ones mentioned2,3,23,24. This protozoan is common in inhabitants of developing countries, affecting predominantly people living with precarious socioeconomic conditions, inadequate hygiene practices and malnutrition24. The prevalence of this parasite is influenced by local agglomeration, inadequate supply of water, quality of consumed water, lack of basic sanitation, bathroom habits, lack of adequate urban services, age, ingestion of raw vegetables, number of bedrooms and bathrooms per house and the presence of other intestinal protozoa4.

In this study, as well as in others14,23, gender and age were not important variables; however, some authors mention gender as a factor associated to giardiasis27. Age did not present any correlation with the presence of Cryptosporidium spp., but is an important factor7,21. The elderly are more susceptible to having serious illnesses with age advancement, and these diseases can present longer duration thereby increasing the chance that individuals may have higher rates of secondary infections, such as enteroparasitosis9

The origin of the institution where the elderly lived was important only when associated with G. duodenalis, and there is no basis of explanation for this association. Nevertheless, the water quality and the level of basic sanitation in the municipality are highlighted as having the potential to influence the quality of life and health of the local population.

Good personal hygiene habits are fundamental for reducing the transmissibility of pathogens. Poor hygiene behavior, contaminated hands, food and water can spread pathogens11.

Contact with domestic animals increased the risk of the elderly acquiring G. duodenalis by 15.34 times. The transmission of this protozoan can occur from person to person through food, the environment (mainly by direct contact with contaminated soil and water) or contact with animals. The understanding of Giardia transmission from dogs and other animals to humans and vice versa depends on more biological, molecular and epidemiological studies17.

The time of the last coproparasitological examination proved to be an important variable in the presence of Cryptosporidium spp. infection. For some authors, despite the clinical examination being the first step in the diagnosis of protozoa infection, the parasitological examination is essential for establishing the presence of the parasite in the individual3.

The 4.8% prevalence of infection rate was observed among the nurses who cared for the elderly in this study. As they are the professionals responsible for the hygiene and medication of the institutionalized elderly, they can be a source of infection for those elders. Direct person-to-person transmission occurs mainly in closed communities, such as children's day care centers, orphanages and nurseries26.

The association between the frequency of hand washing and the positivity of G. duodenalis in the health professionals was observed in this study. It is expected that higher frequency in hand washing decreases the likelihood of the presence of pathogens. However, factors such as water quality and the procedure used in hand washing can be critical in determining the presence of intestinal protozoan cysts and thus, leading to the contamination of these professionals.

The presence of G. duodenalis among the food handlers is important because one positive individual can be the source of contamination to others. The food handlers are responsible for ensuring that the food remains healthy throughout its preparation process16. Approximately 10 to 20% of food-borne disease outbreaks are resultant from contamination by food handlers30.

The positivity for G. duodenalis, Cryptosporidium spp. and E.histolytica/dispar demonstrate that ILPI are supportive environments to the occurrence of these infections due to contact between the elderly, nurses/nursing, technicians/caregivers and food handlers.



We are thankful to the directors, coordinators, staff and elders at the Long Term Residency Institutions for collaborating with the execution of this study.



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Correspondence to:
Marcia Cristina Cury
Laboratório de Parasitologia
Av. Pará 1720, Bloco 4C
38400-902 Uberlândia, MG, Brasil
Tel. and Fax: +55.34.32182333

Received: 13 April 2012
Accepted: 18 July 2012
FINANCIAL SUPPORT: We are thankful to the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for their financial support.

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