Prevalence of Arbovirus Infections Among Pregnant Women at a Maternity Hospital School

Method: Descriptive, cross-sectional, retrospective, and quantitative study, carried out with data collected from the notification forms filled in during obstetric screening between August 2015 and July 2016. Collected data about age, sex, place of residence, color, education level, if pregnant, municipality of the occurrence, clinical data related to disease or injury and the information on the achievement and results of the laboratory tests that are used as criteria of confirmation.


Introduction
In the group of emerging and re-emerging infectious diseases, arboviruses are regarded as major challenges for public health.Arbovirus is the nomenclature used for viruses transmitted and spread in nature in cycles involving hematophagous arthropods (such as Aedes aegypti and Aedes albopictus) and vertebrate hosts.These viruses have sufficient viremia in the vertebrate host to initiate productive infection and trigger various signs and symptoms [1].
It is estimated there are more than 545 arbovirus species, out of which more than 150 are related to diseases in human beings.Arboviruses have become significant and constant threats in tropical regions due to rapid weather changes, deforestation, population move, disorderly occupation of urban areas, poor sanitation that favors viral spread and transmission.Arboviruses are transmitted by the blood of viremic patients, through hematophagous insects.Brazil has a large land area, located in a predominantly tropical zone, providing suitable sites for vector existence, thus it favors the occurrence of arboviruses.Regarding Aedes aegypti, the vector is observed in all Brazilian regions, in more than 4,000 municipalities [2][3][4][5][6].
In Brazil, when the subject is related to the most common arboviruses, until 2014 only dengue fever stood outdue to transmission through Aedes aegypti.In July or August 2014, confirmed cases of chikungunya began to appear in individuals from Central American countries, mainly Haiti and the Dominican Republic.In Brazil, the first autochthonous cases of chikungunya were identified in the state of Amapá.In May 2015, the Ministry of Health (MH) confirmed 16 cases of zika virus in Brazil.In August 2015, the zika virus was already observed in the states of Bahia, Rio Grande do Norte, São Paulo, Alagoas, Pará, Roraima, Rio de Janeiro, Maranhão, Pernambuco, Ceará, Paraíba, Paraná, and Piauí [2].
According to recent estimates, at least 390 million cases of dengue fever occur each year worldwide, out of which 96 million are symptomatic.As for chikungunya, there are at least 14,000 reported cases in 44 Brazilian municipalities, with autochthonous transmission, and its epicenter is mainly the state of Bahia.There are also records of autochthonous transmission of the zika virus in 18 Brazilian states, with greater transmission in the Northeast region -60,000 estimated cases [3].
Pernambuco has been reporting cases of dengue fever since 1987.Within this period, the main epidemics occurred in 1997,1998,2002,2015, and 2016.In 2015, the differential impact of epidemic consisted in circulation of the four disease serotypes and confirmation of the first autochthonous cases of chikungunya and zika fever.The latter has been responsible for a change in the pattern and an increased number of microcephaly cases.
In 2016, until December 3, there were 111,616 suspected cases of dengue fever in Pernambuco.Regarding chikungunya, 58,097 cases were reported in 183 municipalities and the district of Fernando de Noronha.Also, 11,347 cases of zika fever were reported in 151 municipalities and the district of Fernando de Noronha [5].
Chikungunya, dengue fever and zika fever are arboviruses that manifest clinically as febrile, nonspecific diseases whose clinical diagnosis, at first, is difficult to differentiate, since their symptoms are very similar.The current scenario is extremely complicated, considering that except for dengue fever, the availability of laboratory diagnosis is limited, making it hard to differentiate infections [3].
In the midst of arboviruses epidemic, which reappeared in 2015, a considerable increase was observed in the number of cases of newborn infants with microcephaly (a neurological condition where a baby's head is smaller when compared to the pattern of other babies of the same sex and age), mainly in the Northeast region.The association between this malformation and zika virus infection was reinforced by detecting the virus genome in the amniotic fluid of infected pregnant women [5].
Considering microcephaly, Pernambuco notified, between August 1, 2015, and November 26, 2016, 2,204 cases.Out of these, 1,467 were discarded, 395 were confirmed, and 248 remained under investigation.In addition, 94 deaths remained under investigation.Due to the occurrence of an epidemic of these infections in Brazil, a demand has emerged to combine the efforts of professionals from all areas in the health field to care for affected people, either the mothers, their children, or their families, in order to inform and support women in childbearing years.
Faced with this issue, we analyzed the magnitude of infections caused by the arboviruses dengue, chikungunya, and zika among pregnant women who seek care in the obstetric emergency service of a maternity hospital school in Recife.

Objective
Survey the prevalence of arbovirus infections among pregnant women provided with care at a maternity hospital school in Recife.

Method
This is a descriptive, cross-sectional, retrospective, and quantitative study.The locus of research was Recife, capital city of Pernambuco, Brazil, at the maternity unit of the Integrated Health Center "Amaury de Medeiros" (CISAM), which belongs to the University of Pernambuco (UPE), a reference service for primary and secondary care to pregnant women, where low-and high-risk obstetric and gynecological clinical actions are taken, as well as learning, research, and university outreach activities.
Data were obtained at two moments: first by surveying all notification forms of suspected arboviral infection cases during pregnancy (documents from the Brazilian Information System for Notification of Diseases -SINAN), registered from August 2015 to July 2016 (period of epidemic in Pernambuco).This system is mainly used by the notification and investigation of cases of diseases that are included in Brazil's national list of compulsorily notifiable, where are recorded information on the type of illness or health impairment which require information.Notification, age, sex and place of residence of the individual, color, education level, if pregnant and address.It is also recorded the municipality of the occurrence, clinical data related to disease or injury and that are presented by the individual and the information on the achievement and results of the laboratory tests that are used as criteria of confirmation or disposal.The family income was calculated from the sum of the total income received by all the components of the family and divided by the number of people that form this family group.The result was compared to the value of the Brazilian minimum wage at the time of the study (which corresponded to 880 reais = 281 dollars).
The second moment consisted in telephone contact with pregnant women whose data were incompletely reported, in order to aggregate all variables of interest, including detailed signs and symptoms, laboratory data (dates of exams and laboratory results), and supplementary epidemiological data.
Data collection was conducted in August and September 2016 and 103 forms were analyzed.
The data obtained were entered a spreadsheet in the software Microsoft Excel, version 2013, and the software Epi Info, version 3.5.2,was also used for quantitative analysis and descriptive statistics.
This study observed the rules and guidelines of research involving human beings, according to Resolution 466/2012, from the Brazilian National Health Council (CNS), it was registered in the Brazil platform after approval by the Research Ethics Committee of the University of Pernambuco (REC/UPE), under the Brazilian Certificate of Submission for Ethical Assessment (CAAE) 58061516.6.0000.5192.

Results
Data in Table 1 refer to the collection of all 103 notification forms of suspected and confirmed cases of arbovirus infection(dengue, zika, and chikungunya) among pregnant women provided with care at the CISAM screening within the period from August 2015 to June 2016.
Most pregnant women whose clinical signs suggest arbovirus infection within the study period were> 20 years old (60.2%) and teenagers (39.8%).Also, most of them declared to be black or brown (75.7%), single (59.2%), and reported to be educated to High School level (41.8%).Regarding family income, the values mentioned by most pregnant women corresponded to 1 to 3 minimum wages (63.2%); as for occupation, 42.7% were housewives.Most pregnant women came from Recife (72.8%),where the Health District II (21.3%) stood out, and Olinda (24.3%).
In 100% of the notified cases, the pregnant women were cure.However, the analysis of repercussions of infection on the fetus/newborn infant revealed a prevalence of 9.7% of microcephaly when all cases were considered together, a prevalence of 20% when only confirmed cases of dengue, chikungunya, or zika were selected, and a prevalence of 62.5% when specifically addressing zika cases confirmed by laboratory examination.(Figure 5) The cases of zika virus infection were analyzed separately, both those that evolved to microcephaly (62.5%) and those without microcephaly (37.5%).Source: Prepared by the authors.
toms, followed by headache (46%).Many of these symptoms occurred in association and other symptoms were highlighted, such as pruritus in the skin, nausea, and vomiting (Figure 2).Among the 50 arboviruses cases confirmed by serology, the prevalence of dengue infection stood out(44%), followed by chikungunya (34%) and zika (22%).(Figure 3) Considering the cases confirmed by serology, infections among the pregnant women studied predominantly in the first trimester of pregnancy (54.5%),Considering the gestational period in which the infection occurred, the microcephaly cases took place at the first and second trimesters (60%).The pregnant women had to be hospitalized in 66.7% of the cases without microcephaly and in 100% of the cases that evolved to microcephaly.
Among the confirmed microcephaly cases, 80% of the pregnant women underwent ultrasonography with analysis of fetal morphology and the latter showed changes from the perspective of cephalic perimeter.Among the women with zika whose children were born normal, 33.3% underwent ultrasonography and we found normality.
Evaluation on the gestational age at which the children whose mothers had zika virus infection were born showed that most of them were fullterm, both those who had microcephaly and those with normal cephalic perimeter (68.7%).Only 18.8% were born with less than 37 weeks.All were born alive and remained alive until October 2016.
The babies with microcephaly were born predominantly below normal weight for gestational age (90%), with < 2.5 kg.The cephalic perimeter of newborn infants with microcephaly ranged from 23 to 32 cm and 70% of the cases had a perimeter between 30 and 32 cm.
Computed tomography evaluation occurred in 100% of the microcephaly cases, however, among the women who had zika whose children were not born with microcephaly, 66.7% did not undergo computed tomography or the tomography result was not registered (Table 2).

Discussion
Arboviruses have posed a major challenge to public health due to weather and environmental changes and deforestation, which favor viral spread and transmission, as well as transposition of the barrier between species [6].
Arbovirus contamination and the growing numbers registered throughout the country bring proof that an epidemic is currently underway, especially dengue, chikungunya, and zika.
Study data showed a profile of young and low income women who live, most of them, in sites at greater risk of contamination and favorable to the transmitting mosquito species, since these areas are located in peripheral regions with little investment in clean-up, adequate garbage collection, and actions to fight against disease and increase population awareness, despite all efforts made after the onset of the arbovirus epidemic.However, it is worth stressing that arboviruses, especially dengue, affect the population in all Brazilian states, regardless of social class [7,8].
This study drew attention to the fact that most women did not have access to the serological confirmation of infection.It is worth highlighting this fact because the diagnosis of arboviruses is still a difficulty observed in the health services, both due to the lack of access to specific laboratory tests and the similarity between their symptoms [3].
The recent entry of new arboviruses poses a challenge to health professionals and scholars due to the need for active and ongoing research on the specific symptoms and serology, vectors, etiologic agents, and environmental and social factors that may be associated with epidemics and the emergence of new cases.It is noteworthy that, although the lethality of arboviruses is considered as low, cases of co-infection with other arboviruses have already been reported in patients from other continents, something which leads to a better attention to patients' diagnosis, as well as to the study of the interaction between these viruses in human beings [9][10].
According to the protocol recommended by the MH, pregnant women with symptoms of active exanthematous disease should be provided with care at the health services and undergo blood collection during the acute phase of disease (up to the fifth day of the onset of lesions) [4].
A strong similarity between the symptoms shown by the women under study was observed, where exanthema, muscular pains, and fever stand out, all common to the three types of arboviruses frequent in Brazil.On the other hand, the infections may be asymptomatic.It is also worth stressing that despite the fact that most patients infected with dengue, zika, and chikungunya show full recovery after the acute phase of disease, some symptoms, such as severe arthralgia of chikungunya can last for weeks or months, interfering with the individual's occupational activities.In the case of zika virus infection, this can lead the patient to develop a syndrome of autoimmune and neurological origin, named as Guillain-Barré, which causes generalized muscle weakness and paralysis.Additionally, zika virus infection among pregnant women may be associated with microcephaly in babies, increasing the need to improve prevention, health surveillance, and control actions related to these infections [10].
Among the three arboviruses studied, dengue was prominent in its occurrence and, although the consequences of dengue virus contamination are considered as lower, for pregnancy, than those of zika virus, they exist and there is evidence that they can affect the fetus and the pregnant woman, leading in some cases to low birth weight, bleeding, and physiological complications during pregnancy or even increased risk of miscarriage.
The major gestational complications occur when diseases emerge in the first and second trimester of pregnancy, a period of great importance in fetal formation [11].Among the women treated at the CISAM outpatient clinic with suspected arboviruses, the majority were in the first trimester of pregnancy.The fact seemed to be worrying because one of the most dramatic contexts that has been related to the introduction of zika virus in Brazil is the outbreak of microcephaly in children because it was already confirmed, in November 2015, by reverse transcriptase polymerase chain reaction (RT-PCR) due to the presence of zika virus in the amniotic fluid of pregnant women whose fetuses had microcephaly.However, there are still few studies on the zika virus in the literature, and the first major outbreak was described in Micronesia in 2007 [12].
When it comes to vertical transmission of arboviruses, we notice that perinatal dengue can cause fetal distress, prematurity, and intrauterine death.Endothelial changes in placental vessels, with increased vascular permeability, may lead to fetal loss.Vertical transmission rates among studies range from 1.6% to 10.5% and the difference may be assigned to maternal disease severity.The occurrence of neural tube malformations in women with dengue up to the 10 th week of pregnancy has been reported, but this association has also been reported in other febrile diseases, and it is believed to be more closely related to pyrexia than to the teratogenic effect of virus.Regarding vertical transmission of chikungunya, it is considered as rare before 22 weeks of pregnancy and, studies, also with animal models, demonstrate non-permissiveness to the passage of virus through the placental barrier du-ring exposure before delivery.However, if the fetus is affected within this period, the reports consist in fetal losses.After 22 weeks, infection occurs more frequently among mothers who are experiencing viremia during delivery.The pathogenesis of placental transmission is not known, yet [12].
In the case of zika, it is believed that increased risk of fetal malformations is associated with maternal infection within the first trimester.The causal link between vertical transmission of zika virus and the occurrence of fetal and neonatal complications was established by the Evandro Chagas Institute (IEC), of the MH, by detecting this virus in the cerebrospinal fluid (CSF), brain, and fragments of several viscera (heart, lung, liver, spleen, and kidney) from a newborn infant who evolved to death soon after birth.Subsequently, these results were reinforced by detecting antibodies of the class immunoglobulin M (IgM) for zika virus in the CSF from 12 children who were born with microcephaly.In addition to this evidence, identifying the zika virus genome in placenta cells in an abortion at the 8 th week, using real-time RT-PCR techniques, something which reinforces the potential of placental transmission [13].
The Pan American Health Organization (PAHO) stresses that although zika virus has already been found in amniotic fluid, as well as in fetal brains, the studies are still recent and they have been conducted with few children, something which makes this type of transmission an unknown fact, as well as whether it can occur in all cases.Microcephaly is a condition where the person's head is smaller in size than the average head size of children of the same sex and age group.It may be diagnosed still during pregnancy, this condition is due to insufficient brain growth during pregnancy or after the baby is born [13].
In this study, congenital malformation, named as microcephaly, occurred in more than half of the newborn infants of mothers who had laboratory confirmation of zika virus contamination during pregnancy, which was predominantly caused within the first and second trimesters of pregnancy, 90% of the newborn infants also had low birth weight (<2.5 kg).
Microcephaly may be multifactorial, with environmental and genetic factors involved.Despite several traces of the relationship between zika virus infection and microcephaly cases in Brazil, further studies are needed to understand viral pathogenicity and other factors that may interfere with the vertical transmission rate (virus factors -such as viral load and virulence, host factors such as presence of other underlying diseases, lack of some micronutrient, gestational age at the time of infection, etc.) and the clinical outcome of pregnancy and the baby [12].
Thus, it is worth notifying the cases defined and fillingin the data collection instrument for pregnant women and newborn infants.This instrument includes information such as: exposure to teratogenic substances, infections, the pregnant woman's previous and current pathological history, and other variables that will contribute to a better understanding of this event (microcephaly and zika virus), considered as unpublished in the literature [13].
Although Pernambuco has been reported as the state with the largest number of notified microcephaly cases (2,259 cases), this study identified it is still hard to perform a confirmatory serology of zika virus infection and morphological ultrasonography.Such data does not corroborate the recommendations by the World Health Organization (WHO), which indicates that the test of zika virus infection should be performed by all pregnant women who have a history of symptoms or signs of zika virus disease.Likewise, whenever possible, health professionals will be able to propose ultrasound within the first trimester to all women during antenatal care, to accurately date pregnancy, and submit them to a basic evaluation of fetalmorphology [13].

Conclusion
This study identified that dengue fever is prominent among arboviruses, followed by chikungunya and zika, which affected young mothers from peripheral neighborhoods and those with a poor sociosanitary structure.
The problems identified were related to difficulty for diagnostic confirmation by serology, monitoring of infected pregnant women, especially regarding morphological ultrasonography.
Microcephaly occurred in 62.5% of the cases of zika virus infection in the first and second trimester of pregnancy.The newborn infants affected by the infection were born full-term, weighing below normal and having a cephalic perimeter between 30cm and 33cm.
This study emphasizes the importance of establishing and consolidating actions to fight against Aedes aegypti, as well as the effective implementation of the clinical protocols and recommendations aimed at the mother and child clientele that is exposed to this mosquito species.It also highlights the need for increasing the provision of specific laboratory tests and improving the quality of records in the notification forms, especially in the case of pregnant women.The creation of actions to fight against the mosquito and the work of several bodies to raise awareness and advise the population are of paramount importance for controlling these diseases.

Figure 1 :
Figure 1: Percentage of confirmed arbovirose cases among pregnant women provided with care at the CISAM between September 2015 and June 2016.Recife, 2017.

Figure 2 :
Figure 2: Prevalence of signs and symptoms related to the occurrence of arbovirus infections among pregnant women provided with care at the CISAM between September 2015 and June 2016.Recife, 2017.

Figure 3 :
Figure 3: Prevalence of confirmed arboviruses among pregnant women provided with care at the CISAM between September 2015 and June 2016.Recife, 2017.

Figure 4 :
Figure 4: Distribution of data related to the occurrence of infection and care provided to pregnant women with arboviruses at the CISAM between September 2015 and June 2016.Recife, 2017.

Figure 5 :
Figure 5: Prevalence of microcephaly considering the general population, confirmed cases of arbovirus infection, and confirmed cases of zika infection among pregnant women provided with care at the CISAM between September 2015 and June 2016.Recife, 2017.

Table 1 .
Sociodemographic profile of pregnant women with notification of suspected arbovirus infection provided with care at the CISAM between August 2015 and June 2016.Recife, 2017.
Source: Prepared by the authors.

Table 2 .
Clinical data of pregnant women infected with zika virus provided with care at the CISAM between September 2015 and June 2016.Recife, 2017.