Strongyloides stercoralis and other enteroparasites in children at Uberlândia city, state of Minas Gerais, Brazil.
ABSTRACT To evaluate the rate of infection by Strongyloides stercoralis and other enteroparasites a survey was conducted in the city of Uberlândia, State of Minas Gerais, Brazil. A total of 900 stool samples from 300 children aging from four months to seven years, randomly selected in ten nursery schools from September 1994 to December 1995, were examined, both by the Baermann-Moraes and Lutz methods. Thirty nine children (13%) were found to be infected by S. stercoralis, 64.1% were boys and 35.9% were girls. Taking all the enteroparasites as a whole the results of the survey pointed out that 265 (88.4%0 of the 300 children were infected by the following: Giardia lamblia, 78.3%; Ascaris lumbricoides, 15.3%; S. stercoralis, 13%; Hymenolepis nana, 6.7%; hookworms, 6%; Enterobius vermicularis, 4%; Hymenolepis diminuta, 4% and Trichuris trichiura, 0.7%. From 265 infected children 64.5% were mono-infected, 27.2% were infected by two parasites and 8.3% had a poly-specific parasite burden. It was concluded that strongyloidiasis is hyperendemic in this area.
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ABSTRACT: Strongyloidiasis is caused by the intestinal nematode Strongyloides stercoralis and it typically occurs in the asymptomatic form. However, it can cause hyperinfection and dissemination in immunosuppressed patients, especially if they are under corticoid therapy. Deﬁnitive diagnosis is made by the detection of larvae in fecal samples. However, as the number of parasites in the host is very low in most cases and the elimination of larvae in the feces is not frequent, the diagnosis of this disease by parasitological methods becomes extremely difﬁcult. The development of reliable immunological assays is an important alternative approach for the diagnosis of strongyloidiasis. One of the major limitations in developing more sensitive and speciﬁc immunological tests is the difﬁculty in obtaining sufﬁcient amounts of parasites to have well-deﬁned fractions or molecules. Thus, the development of reliable serological assays for the strongyloidiasis diagnosis that does not need larvae as antigenic component is imperative.Revista de Patologia Tropical. 01/2006; 35(3):173-184.
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ABSTRACT: RESUMO : Este estudo teve como objetivo diagnosticar a prevalência de parasitoses intestinais em escolares de quinta a oitava séries do Ensino Fundamental de uma escola pública do município de Medianeira, Estado do Paraná, para comparar os resultados obtidos com outros inquéritos realizados no Brasil e no Paraná. Foram realizados 88 exames coprológicos, cujo material fecal recolhido em frascos plásticos limpos e não estéreis, no mesmo dia da coleta, foi processado pelo método de Paratest. Contatou-se que 82,95% dos exames realizados não acusaram vestígios de patógenos intestinais e 17,05% foram positivos para a presença dos seguintes agentes etiológicos: Endolimax nana (33,33%), Entamoeba coli (46,67%) e Giárdia lamblia (13,33%), além de ovos do helminto Stronyloide stercorales (6,67%), com maior prevalência entre estudantes da quinta série (86,67%) do gênero feminino. Nas sexta e sétima séries registraram-se um caso em cada uma (6,67%) e na oitava série não houve nenhuma amostra positiva. Essa constatação pode ser um indicativo da eficiência da ação educativa que a instituição escolar desenvolve a cada ano. Conclui-se que os índices encontrados neste inquérito são semelhantes a outros estudos apontados na literatura e que a prevalência dessas parasitoses intestinais está associada às condições socioeconômicas do bairro. Por isso, recomendou-se a aplicação de novas medidas educativas, porque os infectados são portadores assintomáticos, e, por isso, importantes veículos transmissores, com participação fundamental no estabelecimento e manutenção do ciclo parasitológico que possa se estabelecer na comunidade investigada. Palavras-chave: Parasitoses Intestinais. Protozooses. Helmintíases. ABSTRACT : This study aimed to diagnose the prevalence of intestinal parasites in students from fifth to eighth grades of elementary school to a public school in the municipality of Medianeira, State of Parana, to compare the results with other surveys in Brazil and the Paraná. 88 stool tests were performed, whose fecal stuff collected in plastic bottles clean and not sterile, the same day the collection has been prosecuted by the method of Paratest. Contacted to be 82.95% of the tests have no traces of intestinal pathogens and 17.05% were positive for the presence of the following etiologic agents: Endolimax nana (33.33%), Entamoeba coli (46.67%) and Giardia lamblia (13.33%), in addition to the helminth eggs Stronyloide stercoralis (6.67%), with higher prevalence among students of the fifth series (86.67%) female. In the sixth and seventh grades recorded one case in each (6.67%) and eighth in the series there was no positive sample. This finding may be an indication of the efficiency of educational activity that the school develops every year. It was concluded that the rates found in this survey are similar to other studies found in the literature and that the prevalence of intestinal parasites is linked to socioeconomic conditions of the neighborhood. Therefore, recommended the application of new educational measures, because those infected are asymptomatic and thus important vehicles transmitters, with key participation in the establishment and maintenance of the parasite cycle that can be investigated in the community.
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ABSTRACT: Strongyloides stercoralis, an intestinal parasitic nematode, infects more than 100 million people worldwide. Strongyloides are unique in their ability to exist as a free-living and autoinfective cycle. Strongyloidiasis can occur without any symptoms or as a potentially fatal hyperinfection or disseminated infection. The most common risk factors for these complications are immunosuppression caused by corticosteroids and infection with human T-lymphotropic virus or human immunodeficiency virus. Even though the diagnosis of strongyloidiasis is improved by advanced instrumentation techniques in isolated and complicated cases of hyperinfection or dissemination, efficient guidelines for screening the population in epidemiological surveys are lacking.PLoS neglected tropical diseases. 08/2014; 8(8):e3018.
Laboratório de Parasitologia, Departamento de Patologia, Universidade Federal de Uberlândia, Av. Pará 1720,
38400-902 Uberlândia, MG, Brasil
To evaluate the rate of infection by Strongyloides stercoralis and other enteroparasites a survey was
conducted in the city of Uberlândia, State of Minas Gerais, Brazil. A total of 900 stool samples from 300
children aging from four months to seven years, randomly selected in ten nursery schools from Septem-
ber 1994 to December 1995, were examined, both by the Baermann-Moraes and Lutz methods. Thirty
nine children (13%) were found to be infected by S. stercoralis, 64.1% were boys and 35.9% were girls.
Taking all the enteroparasites as a whole the results of the survey pointed out that 265 (88.4%) of the
300 children were infected by the following: Giardia lamblia, 78.3%; Ascaris lumbricoides, 15.3%; S.
stercoralis, 13%; Hymenolepis nana, 6.7%; hookworms, 6%; Enterobius vermicularis, 4%; Hymenole-
pis diminuta, 4% and Trichuris trichiura, 0.7%. From 265 infected children 64.5% were mono-infected,
27.2% were infected by two parasites and 8.3% had a poly-specific parasite burden. It was concluded
that strongyloidiasis is hyperendemic in this area.
Key words: Strongyloides stercoralis - intestinal parasites - children - Brazil
Strongyloidiasis has heterogenic worldwide
distribution, with three world regions, according
to the predominance of the infection by Strongy-
loides stercoralis (Bavay, 1876): sporadic (<1%),
endemic (1-5%) and hyperendemic (>5%)
(Stuerchler 1981 apud Pires & Dreyer 1993).
The occurrence of S. stercoralis in children
aged from 0-14 years in some Brazilian states is
summarized in Table I.
This study aimed at surveying the prevalence
of S. stercoralis and other enteroparasites in nurs-
ing school children aging from four months to
seven years, in Uberlândia, State of Minas Gerais,
Brazil, from September 1994 to December 1995.
MATERIALS AND METHODS
In 1994 Uberlândia had 49 nursery schools,
from these ten were taken at random. The size of
the sample was calculated according to the formula:
n = Z2 x P x Q/d² (Rodrigues 1986) considering
(Z) of 95%; (d) of 5%; (P) of 10%, obtained in a
pilot study in three nursery schools, and a non-ob-
served value (Q) of 90%; with the size of the sample
(n) evaluated at 138 persons. This sample was
amplified and 300 children were selected at ran-
dom, 30 at each of the pre-determined school; these
children were later identified according to sex and
Supported by CAPES.
+Corresponding author. Fax: +55-34-218.2333
Received 10 July 1997
Accepted 17 November 1997
age following the agreement of their parents or
tutors for their participation.
Three fecal samples from each child were col-
lected in plastic vials without preservatives with
intervals of four to six days. The samples were
stored in boxes with ice and analyzed at the Labo-
ratory of Parasitology of the Universidade Federal
de Uberlândia by the methods of Baermann and
Moraes (BM) (Baermann 1917, Moraes 1948) and
Lutz (Lutz 1919). For more adequate reading of
the slides the larvae were fixed using 0.2 ml of a
10% solution of formalin applied to the residue of
the first method. Five slides were prepared for the
BM analysis and six for the Lutz analysis for each
of the 900 samples. The total number of slides ex-
amination was thus 9900.
All the families of the children received the
results of the laboratory diagnosis. The positive
cases were referred to the Pediatric Polyclinic,
where they received specific treatment.
The data were processed using the analysis of
variance (Anova) and the Students’ t according to
S. stercoralis infection - From the 300 children
studied 39 (13%) were infected with larvae of S.
stercoralis in one of the three periods sampled. Of
these cases, 28 cases were detected only by BM
method (71.8%), nine of them only by the Lutz’
method (23.1%) and two by both methods (5.1%).
These differences were statistically significant by
Anova, GL 2 and 6. Of these 39 cases nine (23%)
were diagnosed only in the first sample; one (2.6%)
in the first and third; one (2.6%) in all three
samples; 14 cases (35.9%) in the second sample
and 14 (35.9%) only in the third sample. These
variations were not statistically significant by
Anova GL 2 and 6. Regarding sex 25 (64.1%) cases
of S. stercoralis were detected in boys and 14
(35.9%) in girls. Children in all ages were infected,
except in those from zero up to one year. Table II
has the number of children studied and test results
by age category. There was no statistically signifi-
cant difference in rates of infection by sex or age.
Positive cases of S. stercoralis varied from 3.3%
to 23.3% in the ten nursery schools.
Other enteroparasites - Of the 300 children
studied 149 (49.7%) were boys and 151, girls
(50.3%). Of these 265 (88.4%) were infected: 132
(49.8%) were boys and 133 (50.2%) were girls.
The distribution of parasites, (excluding the posi-
tive children from the other sample) is represented
in Table III. There were 171 (64.5%) children
mono-infected; 72 (27.2%) bi-infected and 22
(8.3%) poly-infected. From the bi and poly-infected
children there were 32 associated infections of S.
stercoralis: Giardia lamblia, Stiles, 1915, in 17
cases (53.1%); Ascaris lumbricoides, Linnaeus,
1758, in four (12.5%); hookworms either Ancy-
lostoma duodenale (Dubini, 1843) or Necator
americanus, Stiles, 1903, in one (3.1%); Hyme-
nolepis nana (Siebold, 1852) in one (3.1%); to-
gether with G. lamblia and A. lumbricoides in five
(15.6%); G. lamblia and hookworms in two (6.2%);
G. lamblia and H. nana in one (3.1%) and G.
lamblia and Enterobius vermicularis (Linnaeus,
1771) in one (3.1%).
Occurrence of strongyloidiasis in children in different states of Brazil
State No. of
Age categoryNo. of ParasitologicalAuthors (year)
positive (%) methods
0-14 years old
0-12 years old
0-14 years old
0-14 years old
Ritchie, Brumpt Okazaki et al. (1988)
Lutz, Faust Santos et al. (1990)
Lutz, BM Albuquerque et al. (1990)
Lutz Gennari-Cardoso et al. (1996)
Ferraroni et al. (1979)
Alves et al. (1982)
Cutrim-Jr et al. (1985)
Rio Grande do Norte 44410-14 years old159 (2.9)Cavalcanti-Jr et al. (1987)
Rio Grande do Norte
0-13 years old
3 -23 months
1-14 years old
1-12 years old
0-12 years old
Latorraca et al. (1988)
BM: Baermann and Moraes.
Distribution of the 39 cases of Strongyloides
stercoralis by age category of the children studied in
Uberlândia between September 1994 and
0 ¬ 1
1 ¬ 2
2 ¬ 3
3 ¬ 4
4 ¬ 5
5 ¬ 6
6 ¬ 7
Frequency of enteroparasites among children aged
from four months to seven years from ten nursery
schools in Uberlândia, from September 1994 to
ParasitesNo. of positive
To the present time the records of children in-
fected with S. stercoralis in the city of Uberlândia
varied from zero (Berbert-Ferreira & Costa-Cruz
1995) and 2.1% (Gennari-Cardoso et al. 1996).
Both of these studies were conducted using only
one sample per case and using only the Lutz’
Using the procedure of three samples per child
and two methods for diagnosis the rate of infec-
tion was found to be considerably increased, 13%.
It is recommend that for effective diagnosis three
samples are necessary: 71.8% of the cases in the
present research were identified only in second and
third samples. Additionally, the BM method was
able to identify the infection in 30 (76.9%) of chil-
No children of the 0-1 age category were found
to be infected with S. stercoralis compatible with
other research previously published: Marzochi and
Carvalheiro (1978), Almeida and Costa-Cruz
(1988), Berbert-Ferreira and Costa-Cruz (1995),
Guimarães and Sogayar (1995). In the other age
categories the rate of positive cases varied from
10.3% to 20.5% for S. stercoralis involving, 10.9%
to 19% of children, indicating that this parasite is
hyperendemic in the city.
In terms of other detected enteroparasites the
rate of infection (88.4%) was classified as severe
considering the damage that these etiologic enti-
ties may inflict on their hosts. This rate of infec-
tion is the highest found so far in this city, even
when other age categories have been included
(Costa-Cruz et al. 1991, Sá & Costa-Cruz 1991,
Berbert-Ferreira & Costa-Cruz 1995, Costa-Cruz
et al. 1996, Gennari-Cardoso et al. 1996). G.
lamblia was the only pathogenic protozoon de-
tected (235 cases). Seven species of helminthes
were identified, of which A. lumbricoides presented
the highest rate: 15.3%. The occurrence of 35.5%
of children infected by more than one parasite dem-
onstrated that enteroparasites represent a serious
problem to the public health of Uberlândia.
To Maria Cristina Mouta Rink for statistical analy-
sis, to Prof. Dr Uriel Franco Rocha and Dr David G
Francis for suggestions.
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