Cases of Chronic Chagas Disease in the State of Piauí according to the Public reference Laboratory in Health in the Period of 2013-2017

— Chagas Disease (CD) or American trypanosomiasis is a serious infectious disease that presents acute and chronic phases. In Brazil, acute cases of CD are compulsory notification to epidemiological surveillance. Between the years 2013 and 2017, in Piauí state, 350 cases were confirmed in chronic phase, which represent 26.8% of the acute cases registered in Brazil (1304 cases). Therefore, screening of Chagas disease in the chronic phase is of paramount importance for controlling the pathology.


INTRODUCTION
Chagas disease (CD) is serious infection caused mainly by the flagellate protozoan Trypanossoma cruzi, transmitted mostly by Triatomine bugs. Oral contact, organ transplantation, blood transfusion, work accidents and vertical transmission may be other ways to contract the disease 1-2 .
The acute and chronic phases manifest asymptomatically or symptomatically [3][4] . Acute phase takes around 4 to 12 weeks, when the parasite might be found in the blood. The parasite multiply inside macrophages in spleen, liver, lymph node, myocardium and tissues, and may cause inflammatory reactions 5 . Chronic phase emerges after acute phase with decrease of IgM and increase of IgG antibody levels. In that moment the body already suffers great damage and treatment is compromised, what means less chance of cure 6 .
The World Health Organization 7 , estimates between 6 and 7 million people with CD worldwide, According to the described above, it is important to keep control of CD in the state. This study aims to report cases of chronic CD in Piauí state among the years 2013 to 2017, which do not require reporting, based on positive cases detected in a reference laboratory of public health.

II. MATERIAL AND METHODS
For this retrospective study, with a qualitativequantitative approach, secondary data on the chronic form of CD from the reference laboratory in Public Health of Piauí, Brazil, dating from the years of 2013 to 2017, were used. The data were grouped by year and by the city where the patients were living. To define the distribution of people infected by CD per city in Piauí state, the software ArcGis was used.
The data were obtained through the records of the laboratory system, after careful analysis and proper authorization.
The ethical and legal aspects related to the phases of the research were respected according to the National Health Council under resolution 466/2012 and its complementary rules with Ethics Presentation Certificate number 2.962.707.

III. RESULTS
Over the years 2013 to 2017 there were 4029 suspected cases of CD in the reference laboratory of Public Health of Piauí, Brazil, and 350 of those were tested positive to the disease. The laboratory received and processed suspected samples of chronic CD, which were analyzed, and the diagnosis was confirmed by methods including ELISA, IFI and Chemiluminescence. The age range that showed the highest frequency of positive cases for both females (40.76%) and males (32.80%) was between 41 and 61 years old. However, among males the frequency was higher between 25-41 years old (25.40%) and above 61 years old (28.57%) compared to female (Table 1). In this study, it was not possible to identify gender and age of 4 patients (data not shown in the table).  (Fig 1 B).
The Figure 1 (A and B) shows the distribution of CD cases in all state of Piauí with highlight to the cities of Teresina (n= 186; 53.14%) and Riacho Frio (n= 53; 15.14%) with the most of positive tests.
In the Figure 1C

Fig.1: Distribution of CD cases in Piauí state
Source: produced by the authors

IV. DISCUSSION
According to SINAN (Information System of Injury Notification) 12 , in the period of this study, 1304 cases of acute DC were notified in Brazil, whereas in Piauí no case was reported. Despite this, the present work shows 350 positive chronic CD cases in 49 cities in Piauí state with the major frequency between 41 and 61 years old, and no significant difference in frequency between female and male. In addition, it is possible to observe that 2.6% of positive cases are of children among 0 and 11 years old. The maternal anti-T. cruzi of the IgG fraction can cross the placenta and so all newborns of chronic CD mothers are seropositive until approximately the sixth month of life 13 .
It has been reported that chronic patients (average age of 54 years old; 34% female and 31% male) arising from different geographical regions from Brazil, assisted between 2011 to 2014 at the Chagas disease ambulatory from the Evandro Chagas Infectology National Institute (INI-Fundação Oswaldo Cruz, Rio de Janeiro, Brazil), are mainly immigrants from the northeast region, where Piauí is located 14 .
The socioeconomic inequities and the access to the healthcare systems provided to Brazilian population are characteristics that define the differences of mortality rates from CD. In regard to age, the mortality rates increased in patients over 30 years old, with higher occurrence among individuals between 50 and 64 years old; in addition, men
Due to the short duration of the acute phase, chronic cases of CD are more sensitive to epidemiological research. Additionally, reference laboratories apply immunological tests to find only IgG, an antibody characteristically reactive in chronic phase of this disease. There is no specific kit to define the acute phase 7 in the standards determined by the ANVISA (Brazilian National Health Surveillance Agency).
The acute phase of CD presents high parasite count, Romanã sign or inoculation chagoma in the skin are main clinical manifestations. However, is possible to see systemic symptoms as moderate fever, headache, malaise, anorexia and diarrhea. The diagnostic methods used are direct parasitological study via microscopic examination of fresh anti coagulated blood, thin and thick blood smears, or preferably through the identification of motile trypomastigotes in samples following Strout concentration technique. Also a feasible diagnostic method as Polymerase chain reaction (PCR) with host's peripheral blood or cerebrospinal fluid (CSF) samples. However, is possible to find high incidence of false positives because this method is not fully standardized [17][18] .
Generally, chronic CD presents low parasitic load and the patients can manifest digestive form of the disease resulting in the formation of mega viscera, which involves mainly esophagus and colon  . The standards for diagnosis are serological tests, and the strategy recommended by WHO 7 is to combine epidemiologic information with two different serologic assays since commercial ELISA based tests present heterogenic sensitivity and specificity 18-20 . If there is disagreement between the tests, it is recommended to repeat the testing and, persisting the disagreement, a third test with PCR or western blot is recommended [18][19][20][21] . Since CD has been a largely neglected disease it is important to report both acute and chronic manifestations. The diagnosis to chronic CD is complex due to low parasitic load, but notifications of the cases are required to monitor disease incidence throughout the country 22 .

V. CONCLUSION
In this work, we show high frequency of DC in Piauí, mostly in the cities of Teresina and Riacho Frio, in the period of 2013 to 2017, with a short increase in the latter. The screening of Chagas disease in the chronic phase is of paramount importance for the control of the pathology and the case reports help to keep attention on health education of the population.