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Alice Dias, Nilcilene Cordeiro, Elder William

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Soroprevalência de Trypanosoma cruzi em gestantes no Centro-Oeste do Brasil: uma avaliação da transmissão congênita

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Soroprevalência de Trypanosoma cruzi em gestantes no Centro-Oeste do Brasil: uma avaliação da transmissão congênita

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Materiais e Métodos
·O estudo foi realizado no Distrito Federal

Localiza-se no Centro-Oeste do país com uma população estimada de 3.015.268 habitantes

·Estudo (entre 2014 e 2016)

·Secretaria de Saúde do DF

·Estimativa da soroprevalência

·98.895 gestantes

·Gestantes convidadas por meio de ligação telefônica a participar de uma coorte descritiva

Questionário sobre o perfil demográfico, naturalidade, características da habitação

·amostras de sangue coletadas de mães e recém-nascidos

exames parasitológicos e sorológicos: ·Avaliar a presença do parasita em amostras de sangue periférico de mães e recém-nascidos/crianças

-IgG e anti-T IgM

-Ensaio de imunoenzima (ELISA)

-teste de hemaglutinação indireta (HAI)

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Resultados e discussões

Foram testadas 98.895 gestantes durante o pré-natal, das quais 188 (0,19%) foram positivas para DC. A prevalência deT. cruziinfecção em 2014, 2015 e 2016 foi de 0,19% (52/25.871), 0,21% (74/35.790) e 0,17% (62/37.234), respectivamente. A maioria das gestantes estava na faixa etária de 30 a 39 anos

Em recém-nascidos, 40/43 (93%) tiveram autorização da mãe para a coleta de sangue. Destes, 97,5% (39/40) foram negativos, com um único caso positivo confirmando sorologia positiva após 9 meses de idade.

Os participantes viveram ou ainda moram em locais sem asfalto, saneamento básico e referiram contato com paredes de sabugo ou estruturas semelhantes

A transmissão congênita: mostrou 1/40 (2,5%) de soropositividade, correspondendo a um único caso em que o lactente permaneceu positivo para anticorpos contra T. cruzi, após nove meses de idade. Foi possível afirmar que houve um caso de transmissão congênita

Triagem pré-natal : Permitiu a identificação de um caso de transmissão congênita de DC no DF, Brasil. Nossos resultados destacam a necessidade de implementação contínua de um programa de triagem para gestantes e tratamento oportuno para recém-nascidos.

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Seroprevalence of Trypanosoma cruzi in pregnant women in Midwest Brazil: an evaluation of congenital transmission - PMC (nih.gov)

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ABSTRACT

Chagas disease (CD) is caused by the protozoan Trypanosoma cruzi and it is mainly acquired through the vector route, however, blood transfusion and congenital transmission are implicated in the spread of the illness worldwide. The congenital route can occur at any stage of pregnancy and its frequency varies. In the Federal District, in Brazil, the frequency of T. cruzi infection in pregnant women and their offspring has not been updated. Thus, the aim of this study was to estimate the prevalence of T. cruzi infection in pregnant women and the rate of congenital transmission in the Federal District. A cross-sectional study was conducted to estimate the seroprevalence of T. cruzi from 2014 to 2016 in the population of pregnant women attended by the public health service throughout the Federal District and a descriptive cohort for the evaluation of congenital transmission. During the study, prenatal data of 98,895 women were consulted and pregnant women registered in 2016, presenting with positive T. cruzi serology, were part of the descriptive cohort. The estimated prevalence of T. cruzi infection in the three years was 0.19% and the congenital transmission rate was 1/40 (2.5%). Our results have shown that, although the main routes of transmission of CD have been interrupted, there is still a risk of congenital transmission in the Federal District. This present study highlights the need for the continuous implementation of a screening program for pregnant women and timely treatment of infected newborns and children.

Keywords: Chagas disease, Congenital transmission, Pregnant Women, Trypanosoma cruzi, Screening program

INTRODUCTION

Chagas disease (CD) is caused by the protozoan parasite Trypanosoma cruzi and is considered a neglected tropical disease that affects about 6 to 7 million people worldwide1. In recent years, CD has emerged as an important global health problem due to migratory flows spreading the infection to non-endemic countries2. The main route of CD acquisition is through vector transmission, but there are other important routes such as through blood transfusion, consumption of contaminated food and congenital transmission3. In Brazil, effective measures were implemented to control the vector and transfusion transmission pathways, which led to a substantial reduction of new cases of CD4,5. However, there are millions of chronic cases that need attention from health services and public policies and this is a persisting challenge. This group includes women of childbearing age who can transmit the parasite vertically to their offspring4,6.

The transmission of T. cruzi from infected mothers to their fetuses can occur at any stage of pregnancy and most cases of congenital CD are asymptomatic in newborns7. The frequency of congenital transmission varies according to the evaluated region and the diagnostic tests used. In the American continent, the rate is of 2%, but in countries like Argentina, Bolivia and Mexico, it varies between 5% and 7%8. In Brazil, it is around 1.7%9.

The diagnosis of congenital transmission of T. cruzi begins with the detection of infection in pregnant women and is thereafter confirmed through the confirmation of the infection in the newborns of positive mothers. The diagnostic tests in pregnant women should be performed as soon as the pregnancy is confirmed, as any newborn of an infected mother is at risk of infection by the parasite10. Early diagnosis and treatment of the newborn are essential to reduce the risk of developing disabling chronic conditions11. Due to the non-inclusion of T. cruzi diagnosis in the prenatal serological screening in several Brazilian regions, asymptomatic cases of congenital transmission may be underestimated and consequently neglected12.

The congenital transmission is a form of continuity and maintenance of CD. Therefore, knowing the frequency of this condition in women of childbearing age and newborns is extremely important as these data are scarce and outdated in the Federal District (FD)13. The aim of this study was to estimate the prevalence of T. cruzi infection in pregnant women attended by the public service of the FD and to determine the rate of congenital CD transmission.

MATERIALS AND METHODS

Study design and population

The study was conducted in the FD, which is the seat of the government where the Brazilian capital is situated. It is located in the Midwest of the country with an estimated population of 3,015,268 inhabitants14. A cross-sectional study was carried out in the first phase of the study. Data registered in the information system of the Diagnostic Institute of Brasília (FD Health Secretariat), the institution responsible for prenatal screening tests, were consulted for the extraction of information on pregnant women to enable the seroprevalence estimate. The population was composed of all pregnant women attended by the public health system in the prenatal care throughout the FD, between 2014 and 2016, totaling 98,895 pregnant women. In the second phase, women registered in 2016 who tested positive during the prenatal care were invited through a phone call to participate in a descriptive cohort with the objective of evaluating the congenital transmission. A questionnaire on the demographic profile, place of birth, housing characteristics, socioeconomic and clinical data, knowledge, attitudes and practices regarding CD was applied to the women who had formally accepted to participate. In addition, blood samples were collected from mothers and their newborns. Newborns' samples were collected after birth and after nine months of age. The samples were submitted to parasitological and serological tests. The application of the questionnaire and the collection of samples occurred between September 2017 and June 2018.

Parasitological and serological diagnosis

The direct search of T. cruzi was carried out to evaluate the presence of the parasite in peripheral blood samples of mothers and newborns/ children. Samples were evaluated in serological tests for the detection of IgG and IgM antibodies anti-T. cruzi by an Immunoenzyme assay (ELISA) and an Indirect Hemagglutination test (HAI). The ELISA was performed with the kit GOLD ELISA CHAGAS (REM, Sao Paulo, Brazil) following the manufacturer's recommendations. The HAI test was performed according to the CHAGATEST kit protocol (Wiener, Rosario, Argentina).

Statistical analysis

The collected data were entered into an Excel spreadsheet and analyzed by the SPSS software, version 22 (SPSS Inc., Chicago, IL, USA). The descriptive analysis of the results determined the absolute and relative frequencies calculated for the categorical variables.

Ethical approval

The study was approved by the Research Ethics Committee of the Faculty of Medicine/UnB (CAAE Nº 67968717.5.0000.5558/2017). Informed consent was obtained from all the participants.

RESULTS

A total of 98,895 pregnant women were tested during the prenatal care of whom 188 (0.19%) were positive for CD. The prevalence of T. cruzi infection in 2014, 2015 and 2016 was 0.19% (52/25,871), 0.21% (74/35,790) and 0.17% (62/37,234) respectively. Most pregnant women were in the 30 to 39 years age group ( Table 1 ).

Table 1

Year

Age group

n

%

2014

< 20

1/52

1.9

2015

< 20

2/74

2.7

2016

< 20

1/62

1.6

Total

186

100

The geographic distribution of pregnant women in the FD was evaluated by the location of the prenatal care unit in the Administrative Region (AR). In the three years, Ceilandia was the AR that tracked the largest number of pregnant women, a total of 17,878 individuals, corresponding to most of the positive cases, 15.43% (29/188) ( Figure 1 ).

The descriptive cohort study was conducted with (42/62) of mothers who tested positive in 2016 and their 43 babies. One woman died due to complications of CD and was excluded from the study. Concerning the housing characteristics, 50% of the interviewees reported having lived most of their lives in rural areas where there was no asphalt, treated water, sewage and garbage collection. For the socioeconomic variables, approximately 38% (16/42) had as profession/ occupation: "home secretary" (domestic worker), and (22/42) did not work. Most of the families income ranged from 1 to 3 minimum wages. Regarding the demographic variables, the majority came from Bahia State, Northeast of Brazil ( Table 2 ).

Table 2

Data

(n)

%

Federated unit of birth

Educational level

Familiar income (in minimum wages)

In relation to knowledge, attitudes and practices regarding CD, more than 80% reported having knowledge about the disease and they knew how the disease can be acquired. However, the degree of uncertainty on transmission pathways such as blood transfusion/ organ donation and whether the disease could be acquired through the contact with a sick person was approximately 33% each. The majority stated that they had knowledge about the triatomine, and when questioned on the contact with the insect vector (28/42- 66.7%) responded positively and (7/42- 16.7%) admitted that they had already been bitten by triatomines. Regarding the conduct when the vector is found in the home environment, more than 70% confirmed to have already killed the insect immediately after its detection.

Regarding the knowledge on the positivity to T. cruzi infection, (28/42 -66.7%) said that they became aware during the prenatal care in 2016. Among the interviewees who already knew about the positivity, 50% were aware of the situation before the prenatal care. The mothers who said that they knew or suspected the possible route of infection (13/15) stated that it may have occurred due to the bite of the insect vector and (4/42- 9.5%) had already received blood transfusions. In respect to the clinical signs that could be related to CD, the most common complaints were: tiredness, tachycardia, arrhythmia and constipation. Most mothers with CD symptoms did not have or had any type of medical follow-up and around 45% received specific care in the private sector. Concerning the family history of CD, 69% responded positively. The results of the interviews are summarized in Table 3 .

Table 3

Question

(n)

%

Knowledge of CD

Knowledge about the transmission of CD

Knowledge about the vector

Knowledge about congenital transmission

Knowledge about CD symptoms

Knowledge about CD treatment

Recognize the vector insect

Had contact with the vector insect

Sting by the insect vector

Conduct regarding the insect vector

Knew the positive result for CD before prenatal care

Positive result knowledge

Clinical signs related to CD

Medical care to CD

CD drug treatment

In relation to the seroprevalence in newborns, 40/43 (93%) had the mother's authorization for the blood collection. Of these, 97.5% (39/40) were negative, with a single positive case confirming positive serology after 9 months of age. The child was treated at the University Hospital of Brasilia, where the infant was evaluated and received antiparasitic treatment for 60 days.

The direct parasitological test showed negative results for all tested samples of seropositive mothers and their children.

DISCUSSION

Similar studies performed in Brazil have shown that the frequency of CD infection in pregnant women in Brazil is between 0.1 and 0.5%15-17. However, the prevalence found in our study is lower when compared to other countries in Latin America, whose rates range from 3.2 to 23.6%18-21. The high frequency found in pregnant women with more than 32 years of age is similar to other findings that have found age as a factor associated with the risk of infection by T.cruzi due to the accumulated exposure over the years18,22.

The locality with the highest number of pregnant women screened and seropositive for T. cruzi was Ceilandia, the most populous region with a low per capita income in the FD23. Most immigrants in the FD (52.15%) came from the Northeast of Brazil and Ceilandia is home to the majority24. The level of education of the interviewees is higher than the general population of the FD, however, the family income was below the average and most are participants were unemployed24. The participants had lived or still live in places without asphalt, basic sanitation, and referred contact with cob walls or similar structures, supporting that seropositivity is more frequent among the less socially and economically favored population25.

The main knowledge of mothers about CD was related to vector transmission. This is justifiable due to the contact with these insects during childhood. Regarding the lack of knowledge about CD symptoms, this may be related to the fact that most are asymptomatic. This lack of symptoms makes the search for health services less common and may be related to the fact that most of them become aware of their seropositivity only in the prenatal care. In addition, the scarcity of guidelines and the lack of information on the risk of congenital transmission by health professionals has been reported. These perceptions were also pointed out by Bolivian immigrants in Spain26. We observed that the interviewees did not know how to proceed correctly if they find the insect vector in the home environment. The knowledge of the community on how to behave if they find triatomines is extremely important and should be articulated to the practices of community collaboration with the surveillance and control agencies27.

In respect to the investigation of congenital transmission, our study showed 1/40 (2.5%) of seropositivity, corresponding to a single case in which the infant remained positive for antibodies against T. cruzi after nine months ofage. Given the exclusion of other routes of transmission and the age of the infant, it was possible to affirm that there was a case of congenital transmission. The frequency found remained within the national range28, which varied from 0 to 5.2%.

The small number of mothers and babies evaluated can be considered a limitation of our study, as it was not possible to find all mothers due to the change of telephone numbers, home address or even moving to a different State. Studies performed with a larger sample can be more conclusive, however, it is worth mentioning that our study represents a first step in updating the data concerning the congenital transmission of CD in the FD, Brazil.

Better quality of life and prognosis of infected mothers in addition to timely treatment of congenital cases allowing high cure rates justify the efforts and the importance of prenatal screening programs. Serological screening for T. cruzi infection in the prenatal care has not yet been implemented at the national level. Consequently, due to the poor monitoring of pregnant women and their children especially in endemic regions, many cases of congenital transmission might be underreported and neglected in Brazil12.

In conclusion, the prevalence of pregnant women with T. cruzi infection and the frequency of congenital transmission shown in the present study were similar to other reports in Brazil. Prenatal screening is extremely important for the knowledge of positive cases in pregnant women. It allowed the identification of a case of congenital CD transmission in the FD, Brazil, which would probably be undetected as the child was asymptomatic and was not monitored by the health service. Our results highlight the need for the continuous implementation of a screening program for pregnant women and timely treatment for newborns and infected children in Brazil.

Footnotes

FUNDING.This study was financed in part by the Agency for Training Human Resources (CAPES), Ministry of Education, Brazil - Finance Code 001.

REFERENCES

10. Carlier Y, Truyens C. Maternal-fetal transmission of Trypanosoma cruzi. In: Telleria J, Tibayrenc M, editors, editors. American Trypanosomiasis: one hundred years of research. Amsterdam: Elsevier; 2010. pp. 539-581. [ Google Scholar]

Articles from Revista do Instituto de Medicina Tropical de São Paulo are provided here courtesy of Instituto De Medicina Tropical De Sao Paulo

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Seroprevalence of Trypanosoma cruzi in pregnant women in Midwest Brazil: an evaluation of congenital transmission

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Chagas disease (CD) is caused by the protozoan Trypanosoma cruzi and it is mainly acquired through the vector route, however, blood transfusion and congenital transmission are implicated in the spread of the illness worldwide. The congenital route can occur at any stage of pregnancy and its frequency varies.

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A doença de chagas foi descoberta por Carlos Chagas, em 1909, causada pelo protozoário Trypanosoma cruzi e transmitida ao homem por insetos triatomíneos, conhecidos como “barbeiros”.

A mãe portadora da doença de Chagas pode transmitir durante a gravidez ou aleitamento materno

Objetivo : Estimar a prevalência de Trypanossoma cruzi e sua infecção em gestantes atendidas pelo serviço público do DF e determinar a taxa de transmissão da Doença de Chagas congênita.