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Revista de Saúde Pública

Print version ISSN 0034-8910On-line version ISSN 1518-8787

Rev. Saúde Pública vol.53  São Paulo  2019  Epub Sep 02, 2019

https://doi.org/10.11606/s1518-8787.2019053001146 

Original Article

Personal protective measures of pregnant women against Zika virus infection

Vladimir Antonio Dantas MeloI 
http://orcid.org/0000-0001-6124-6029

José Rodrigo Santos SilvaI  II 
http://orcid.org/0000-0002-1918-7122

Roseli La CorteI  III 
http://orcid.org/0000-0001-5017-3725

IUniversidade Federal de Sergipe. Programa de Pós-Graduação em Biologia Parasitária. São Cristovão, SE, Brasil

IIUniversidade Federal de Sergipe. Departamento de Estatística e Ciências Atuariais. Centro de Ciências Exatas e Tecnologia. São Cristovão, SE, Brasil

IIIUniversidade Federal de Sergipe. Departamento de Morfologia. Centro de Ciências Biológicas e da Saúde. São Cristovão, SE, Brasil


ABSTRACT

OBJECTIVE

To evaluate the adherence of pregnant women to personal protective measures against mosquito bites, recommended by the Ministry of Health, and to investigate the factors associated with the non-adoption of these measures.

METHODS

We interviewed 177 pregnant women between November 2016 and February 2017 in the 10 basic health units of the municipality of Propriá, state of Sergipe, two located in the rural area and eight in the urban area, during prenatal appointments, to raise information about the use of preventive measures against the vector transmission of Zika virus. Data were analyzed using descriptive statistical methods, chi-square test or Fisher’s exact test, and the odds ratio was calculated. The independent variables were grouped by the analysis of principal components, and the dependents (the use of repellent, mosquito nets, garments, screens and insecticides) were analyzed using the logistic regression method.

RESULTS

Among the measures recommended by the Ministry of Health, mosquito nets were the most used by pregnant women living in rural areas and with low education level, while the repellents were more used by women in the urban area and with higher education level. Women in a vulnerable socio-economic situation presented a risk 2.4 times higher for not using screens in their homes, 1.9 times higher for not changing clothes and 2.5 times higher for not using repellent than pregnant women in better economic conditions.

CONCLUSIONS

The socioeconomic status of pregnant women, especially among the less privileged, influenced the use of protective measures against Zika virus, from the purchase of repellent, clothing, insecticides to other resources in the municipality of Propriá, SE.

Key words: Pregnant Women; Zika Virus Infection, prevention & control; Arbovirus Infections, prevention & control; Insect Repellents; Mosquito Nets, utilization; Socioeconomic Factors

RESUMO

OBJETIVO

Avaliar a adesão de gestantes às medidas de proteção individual contra picadas de mosquitos, recomendadas pelo Ministério da Saúde e investigar os fatores associados à não adoção dessas medidas.

MÉTODOS

Foram entrevistadas 177 gestantes entre novembro de 2016 e fevereiro de 2017 nas 10 unidades básicas de saúde da cidade de Propriá, SE, duas localizadas na zona rural e oito na zona urbana, durante as consultas de pré-natal, para levantar informações sobre o uso de medidas preventivas contra a transmissão vetorial do zika vírus. Os dados foram analisados utilizando métodos de estatística descritiva, teste do qui-quadrado ou teste exato de Fisher, e foi calculado o odds ratio . As variáveis independentes foram agrupadas por meio da análise de componentes principais, e as dependentes (uso de repelentes, mosquiteiros, vestimentas, telas e inseticidas) foram analisadas pelo método de regressão logística.

RESULTADOS

Entre as medidas recomendadas pelo Ministério da Saúde, o uso de mosquiteiros foi a mais utilizada por gestantes residentes na zona rural e de baixa escolaridade, enquanto os repelentes foram mais utilizados por mulheres da zona urbana e com maior tempo de estudo. Mulheres com situação socioeconômica vulnerável apresentaram risco 2,4 vezes maior de não utilizar telas em suas residências, 1,9 vezes maior de não mudar o modo de se vestir e 2,5 vezes maior de não usar repelentes do que gestantes em melhores condições econômicas.

CONCLUSÕES

A condição socioeconômica das gestantes, especialmente entre as mulheres menos favorecidas, influenciou o uso das medidas de proteção contra o zika vírus, desde a compra de repelentes, vestimentas, inseticidas até outros recursos na cidade de Propriá, SE.

Palavras-Chave: Gestantes; Infecção pelo Zika virus, prevenção & controle; Infecções por Arbovirus, prevenção & controle; Repelentes de Insetos; Mosquiteiros, utilização; Fatores Socioeconômicos

INTRODUCTION

The entry and dispersion of Zika virus (ZIKV) in Brazil has been silent from the beginning of 20141 . However, the severity of the situation surfaced in the second semester of 2015, when an alarming number of cases of microcephaly was registered in the Northeast of the country2 . In response to the microcephaly epidemic in Brazil, rapidly associated with ZIKV, the World Health Organization (WHO) declared the ZIKV, at the beginning of 2016, as “a public health emergency of international concern,” highlighting the importance of stronger measures to reduce infection, especially among pregnant women and in fertile age3 .

The vertical transmission of the virus was identified as the main cause of the congenital Zika virus syndrome in newborns, since the ZIKV can cross the placental barrier efficiently4 , mainly in the first, but also in the second and third trimesters of pregnancy, although with less frequency5 .

Aedes aegypti was incriminated as the main vector of ZIKV6 , a large vector control campaign was instituted throughout the country, called Zika Zero, in order to reduce the infestation levels of this mosquito species7 . However, the strategies to control Ae. aegypti in Brazil, whether by the mechanical elimination of breeding sites, or by the use of insecticides, have obtained disappointing results, with constant dengue epidemics8 and resistance to several classes of insecticides widely distributed9 .

Given this scenario, the Ministry of Health (MH) recommended the adoption of personal protective measures against the bites of ZIKV-transmitting mosquitoes, especially for pregnant women. These measures include the use of commercial repellents and complementary mechanical protective measures. The mechanical protection recommended by MH refers to wearing clothing that prevents bites (long-sleeved shirts, coats, socks, pants and long skirts), protective screens on doors and windows and mosquito nets10 .

Without vaccine or specific treatment for ZIKV and mainly due to the congenital syndrome associated with ZIKV infection, the focus for transmission control was on preventive measure and health promotion. Based on this assumption, and considering the recommendations of the Ministry of Health disseminated in all media at the time7 , 11 , the objective of this study was to assess which personal protection measures were employed by pregnant women residing in the northeastern region of Brazil, the most affected by the epidemic between 2015 and 2016, as well as to identify the factors associated with the non-adoption of preventive measures.

METHODS

This study was developed in the municipality of Propriá, Sergipe, northeastern region of Brazil (10°13’48”S, 36°50’22’’W), with an estimated population of 28,451 inhabitants (24,390 living in urban and 4,061 in rural areas) and human development index (HDI) of 0.66112 . The municipality has 10 basic health units (BHU) responsible for monitoring a defined number of families, with actions to promote, prevent and recover the community health. Two BHUs are located in the rural area and eight are located in the urban area.

The epidemiological situation of the municipality of Propriá was considered of medium risk for dengue transmission, with 1.1% of the properties infested with Ae. aegypti larvae in the Index Rapid Survey for Aedes aegypti (LIRAa) carried out from 12 to 16 September 2016. Propriá had three reported cases of microcephaly until the end of 2016, with one confirmed case13 .

A cross-sectional study was carried out, with a survey of information from pregnant women about the use of personal protective measures against ZIKV infection by Ae. aegypti mosquito bites. The interviews were conducted during prenatal care at the BHU of the municipality through a semi-structured form applied by an interviewer between November 2016 and February 2017. Two pilot studies were conducted with women of different age groups to assess the understanding of the questions and estimate the duration of the interview (15 to 30 minutes). After the pilot study, the final form was drawn.

To determine the sample size, the confidence level of 95% and sample error of 5% was considered, while the population parameters p and q were fixed in 50%. The reference for calculating the number of pregnant women was the sum of live births, stillbirths and abortions in 2015 in the database of MH14 . A stratified sample was calculated to maintain the proportion of pregnant women living in rural (20%) and urban (80%) areas, resulting in a minimum sample of 174 pregnant women, with 34 living in rural area and 140 in urban areas. The inclusion criteria were pregnant women aged more than 15 years (mean age to finish the elementary school in Brazil), residents in Propriá and who received prenatal care at the BHUs of the Unified Health System (SUS).

Data Analysis

The collected data were typed (double-typing) in a spreadsheet using Microsoft software® Excel 2013. Data analysis involved descriptive statistics techniques that understood the attainment of absolute and relative frequencies of nominal variables. Bivariate analyses were performed, with crosses between variables using the chi-square or Fisher’s exact test and odds ratio (OR). The confidence level employed was 95%.

A logistic regression model was adjusted, assuming as response variables: no use of repellents, no use of mosquito nets, no use of long clothes, no use of screens, and no use of insecticides. The principal component analysis (PCA) was used to solve multicollinearity problems of the set of 20 independent variables selected. The inclusion criteria were the scores that presented an eigenvalue higher than or equal to 1. The weight (importance) of each variable in the construction of each component was observed according to the coefficients generated for each original variable, and the variables of higher weight were used to name the components. The statistical analyses were conducted on the R programming, version 3.4.0.

Ethical Aspects of the Study

This study was approved by the Research Ethics Committee of the Federal University of Sergipe (Protocol 1.807.743). All pregnant women were informed of the objectives of the study and invited to sign the informed consent form authorizing their participation and use of the information granted for the purpose of the study. All information was kept confidential to maintain the privacy of the respondent. There was no programmed intervention with the pregnant women, and the norms of the National Health Council of the Ministry of Health established in resolution 466/2012, which regulates research in human beings, were respected.

RESULTS

Of the total 183 pregnant women approached, five were not included because they were younger than 15 years old (age stipulated to finish elementary school), and one woman refused to participate in the interview. Thus, 177 pregnant women were interviewed, 34 from the rural area and 143 from the urban area. The median age was 25 years (amplitude: 15 to 42), with a predominance of those aged 15 to 25 years (55%). Most women (73%) had less than eight years of schooling (41%) and lived with their partners (70%). Only 10% of the sample had college degree or some college, 28% had paid occupation and most lived in the urban area (80%) ( Table 1 ).

Table 1 Demographic and social characteristics and gestational period of the pregnant women interviewed in the municipality of Propriá, state of Sergipe, from November 2016 to February 2017. 

Characteristic Frequency %
Location
Rural area 34 20
Urban area 143 80
Color
White 33 19
Brown 130 73
Black 14 8
Age group (years)
15–20 51 29
21–25 46 26
26–30 44 25
31–35 22 12
36–40 12 7
41–45 2 1
Marital status
Married 72 41
Single 52 29
Common-law marriage 51 29
Divorced 2 1
Education level
Some elementary or middle school 51 29
Elementary school 21 12
Some high school 21 12
High school 66 37
College degree 18 10
Occupational situation
Employed 49 28
Unemployed 128 62
Bolsa Família aid
Receives benefit 68 38
No benefit 109 62
Gestational age (weeks)
< 8 25 14
8–12 21 12
12–16 24 13
16–20 27 15
20–24 25 14
24–28 18 10
> 28 37 22

Among the measures recommended by the Ministry of Health, the most used in descending order (n, frequency) were: repellents (100, 57%), mosquito nets (83, 47%), long clothes (78, 44%) and screens on doors and windows (12, 6%). Only 2% of the sample used all the measures recommended by the MH. The alternative measures to the recommended ones were: pyrethroid insecticides (73, 41%), homemade substances used as repellent (38, 21%), mosquito coil (36, 20%), products containing citronella (30, 17%) and plug in repellents (21, 11%). The use of mosquito nets was the most used preventive measure in rural areas (85%), unlike the urban area (37%), while repellents, especially those of active ingredient based on DEET (N, N-diethyl-meta-toluamide) (94%), were more used in the urban environment (59%) than in the rural environment (47%). The use of repellent was proportional to the increase in education level, while the use of mosquito nets was inversely proportional ( Table 2 ).

Table 2 Relative frequency of the measures adopted by the pregnant women in the municipality of Propriá, state of Sergipe, according to social criteria. 

Variable Education level Area


Elementary School High school Higher education Rural Urban





n % n % n % n % n %
Repellents 26 36.0 59 68.0 15 83.0 16 47.0 84 59.0
Mosquito net 42 58.0 37 43.0 4 22.0 29 85.0 54 37.0
Clothing 20 28.0 43 49.0 14 78.0 14 41.0 63 44.0
Screens 0 0.0 10 11.0 2 11.0 3 6.0 9 8.0
Insecticides 21 21.0 42 44.0 10 56.0 10 29.0 33 44.0
Citronella 6 8.0 18 20.0 6 33.0 5 14.0 25 17.0
Homemade products 18 25.0 19 22.0 2 11.0 5 14.0 34 24.0
Plug in repellents 2 3.0 12 14.0 7 39.0 1 1.0 20 14.0
Mosquito coil 17 24.0 16 18.0 3 17.0 3 9.0 33 23.0

Total 72 100.0 87 100.0 18 100.0 34 100.0 143 100.0

The sleeping room was the main place (56%) of the mosquito coil use, and only 8% used in the external areas of the residences. Among the pregnant women who used insecticide pyrethroid spray as a protective medium, 25% used it daily. Among the natural products containing citronella, 59% used incenses, 17% insecticides, 16% candles, 7% topical repellent and 1% cited the cultivation of the plant. Among the homemade substances used as repellent, 24% used alcohol and cloves, 47% cited body moisturizer, 13% ethyl alcohol, 11% body oils and 5% other substances.

The association with change in clothing included: to present record of arbovirosis, have visual contact with a newborn with microcephaly, use of commercial repellent and use of protective screens on doors and/or windows in the residence. Women who altered their routines, avoiding leaving home, had a 3.5 times greater chance of wearing long clothes on their exits. In addition, women with higher incomes (measured by washing machine possession) had six times more chances of having houses with screens ( Table 3 ). Women in the rural area had a higher perception of mosquitoes in their homes and streets [OR = 3.28 (95%CI 1.74–6.18); p > 0.003)] than women in the urban area.

Table 3 Relationship between preventive measures and social and behavioral variables. 

Variable Category Variable OR (95%CI) p

Mosquito net

No (%) Yes (%)
Formal Education Elementary school 30 (31.9) 42 (50.6) 0.20 (0.06–0.68) 0.011
High school 50 (53.2) 37 (44.6) 0.39 (0.12–1.27)
Higher education 14 (14.9) 4 (4.8) 1
Area Rural 5 (5.3) 29 (34.9) 0.10 (0.04–0.29) < 0.001
Urban 89 (94.7) 54 (65.1) 1

Long clothes

Professional guidance No 64 (64.00) 21 (27.27) 0.21 (0.11–0.40) < 0.001
Yes 36 (36.00) 56 (72.73) 1
Home exits Yes 14 (14.00) 28 (36.36) 3.51 (1.69–7.29) 0.001
No 86 (86.00) 49 (63.64) 1
Commercial repellents No 54 (54.00) 23 (29.87) 0.36 (0.19–0.68) 0.002
Yes 46 (46.00) 54 (70.13) 1
Record of arbovirosis No 84 (84.00) 54 (70.13) 0.45 (0.22–0.92) 0.042
Yes 16 (16.00) 23 (29.87) 1
Baby with microcephaly No 90 (90.00) 53 (68.83) 0.25 (0.11–0.55) < 0.001
Yes 10 (10.00) 24 (31.17) 1

Screens

Washing machine No 90 (54.55) 2 (16.67) 6.00 (1.28–28.2) 0.014
Yes 75 (45.45) 10 (83.33) 1
Commercial repellents No 76 (46.06) 1 (8.33) 9.39 (1.19–74.4) 0.013
Yes 89 (53.94) 11 (91.67) 1
Plug in repellents Yes 14 (8.48) 7 (58.33) 0.07 (0.02–0.24) < 0.001
No 151 (91.52) 5 (41.67) 1
Long clothes Yes 68 (41.21) 9 (75) 0.23 (0.06–0.9) 0.032
No 97 (58.79) 3 (25) 1
Formal Education Elementary School 72 (43.64) 0 (0) - 0.003
High school 77 (46.67) 10 (83.33) 0.96 (0.19–4.82)
Higher education 16 (9.7) 2 (16.67) 1

Plug in repellents

Formal Education Elementary School 70 (44.87) 2 (9.52) 0.04 (0.01–0.24) 0.002
High school 75 (48.08) 12 (57.14) 0.25 (0.08–0.78)
Higher education 11 (7.05) 7 (33.33) 1

When the variables were analyzed together through logistic regression analysis, only the first seven components were used as independent variables in the model, maintaining 59.69% of the total variation of the data set, according to Table 4 . The component economic condition of the pregnant woman (PC 1), which included remunerated work, schooling and material goods, indicated that women with low economic power had 2.5 times more chance of not using the repellent, 2.4 times more chance of not using screens in doors or windows, 1.9 times more chance of not wearing long clothes and 1.4 times more chances of not using insecticides than those with higher economic power. Mosquito nets were used as a preventive measure by low-income people. Regarding PC 2 (social condition), the women assisted by the Bolsa Familia Program (BFP – income transfer programme) and with large offspring had 1.7 times more chances of not using repellents compared with primiparous mothers or with few children and not registered in the BFP ( Table 5 ).

Table 4 Structure of the independent variables in the composition of the principal components in the regression analysis. 

Variable PC 1 PC 2 PC 3 PC 4 PC 5 PC 6 PC 7
Resides in an urban area -0.32 0.03 0.13 0.27 0.38 -0.14 0.55
Age -0.16 0.70 -0.21 -0.08 0.22 0.23 0.18
Common-law marriage -0.05 0.13 0.23 0.17 0.01 0.63 0.06
Works -0.52 0.16 -0.12 -0.03 0.16 0.44 -0.18
Educational background -0.72 -0.24 -0.08 -0.26 0.11 0.04 -0.05
Bolsa Família aid 0.32 0.75 0.00 0.17 -0.05 -0.11 -0.02
drinks alcohol 0.07 -0.12 -0.06 0.75 0.00 0.02 0.03
Smokes 0.08 0.19 -0.01 0.74 0.10 0.02 -0.12
Contact with people with symptoms 0.11 -0.05 -0.03 0.03 0.68 0.19 -0.03
Has a health problem 0.01 0.18 0.01 0.03 0.66 -0.21 0.10
Has stains on the body -0.02 -0.27 -0.31 0.19 0.36 0.04 -0.33
Saw a baby with microcephaly -0.02 -0.24 -0.16 -0.16 0.07 0.59 0.29
Received professional guidance -0.04 0.05 -0.60 0.07 0.03 0.15 0.31
Fewer home exits due to Zika 0.07 -0.04 -0.27 -0.16 -0.03 0.16 0.69
Has a washing machine -0.86 -0.09 -0.02 0.05 -0.14 0.07 0.07
Has a laundry sink 0.87 0.08 0.05 0.04 0.12 -0.08 -0.08
Has children 0.15 0.78 -0.02 -0.01 0.00 -0.08 -0.09
Satisfactory level of knowledge -0.25 -0.09 -0.32 -0.02 -0.15 0.59 -0.09
Media instruction -0.09 -0.01 -0.63 -0.17 0.22 0.08 -0.11
Month of pregnancy -0.04 0.13 -0.65 0.17 -0.16 -0.13 0.08

PC: principal component

Bold values indicate the principal component in which the variable is inserted.

Table 5 Adjustment of the multiple logistic regression model. 

Variable Parameters OR Standard error p
No use of repellent

Intercept -0.590 - 0.212 0.005
PC 1 – Economic condition 0.919 2.506 0.221 0.001
PC 2 – Social condition 0.578 1.782 0.196 0.003
PC 3 – Guidance 0.831 2.296 0.215 0.001
PC 4 – Deleterious habits 0.012 1.012 0.18 0.946
PC 5 – Health condition 0.395 1.484 0.204 0.052
PC 6 – Knowledge about Zika virus -0.690 0.502 0.233 0.003
PC 7 – Preventive habits -0.414 0.661 0.200 0.038

No use of mosquito nets

Intercept 0.177 - 0.186 0.339
PC 1 – Economic condition -0.976 0.377 0.203 0.001
PC 2 – Social condition -0.098 0.907 0.183 0.592
PC 3 – Guidance 0.279 1.322 0.188 0.138
PC 4 – Healthy Habits 0.199 1.220 0.181 0.272
PC 5 – Health condition 0.558 1.747 0.196 0.004
PC 6 – Knowledge about Zika virus 0.15 1.161 0.195 0.442
PC 7 – Preventive habits 0.286 1.331 0.189 0.130

No change of garment

Intercept 0.105 - 0.195 0.590
PC 1 – Economic condition 0.666 1.947 0.200 0.001
PC 2 – Social condition 0.124 1.132 0.188 0.510
PC 3 – Guidance 0.912 2.489 0.211 0.000
PC 4 – Healthy Habits 0.542 1.720 0.237 0.022
PC 5 – Health condition 0.079 1.082 0.191 0.679
PC 6 – Knowledge about Zika virus -0.730 0.482 0.216 0.001
PC 7 – Preventive habits 0.345 0.708 0.193 0.073

Do not use screens

Intercept 3.557 - 0.616 0.001
PC 2 – Social condition 0.479 1.614 0.445 0.282
PC 3 – Guidance 0.525 1.691 0.388 0.176
PC 4 – Healthy Habits 1.156 3.173 0.735 0.116
PC 5 – Health condition 0.486 1.626 0.413 0.238
PC 6 – Knowledge about Zika virus -0.720 0.487 0.291 0.013
PC 7 – Preventive habits -0.176 0.839 0.324 0.587

No use of screens

Intercept 0.400 - 0.169 0.017
PC 1 – Economic condition 0.400 1.492 0.170 0.018
PC 2 – Social condition -0.147 0.863 0.171 0.389
PC 3 – Guidance 0.127 1.135 0.169 0.452
PC 4 – Healthy Habits 0.115 1.122 0.174 0.507
PC 5 – Health condition -0.197 0.821 0.168 0.242
PC 6 – Knowledge about Zika virus 0.113 1.119 0.168 0.503
PC 7 – Preventive habits -0.117 0.837 0.172 0.301

PC 3 (guidance) indicated that women with less than five months of gestation and who did not report having received professional or media education had a 2.2 times higher risk of not using repellent and 2.4 times more chance of not wearing long clothes. PC 4 (deleterious habits) showed that women who consumed alcoholic beverages or smokers had 1.7 times more chances of not modifying the clothing for protection against the Ae. aegypti bites . PC 5 (health condition) revealed that women with health problems and urban residence had 1.7 times more chances of not using mosquito nets than the group of opposing characteristics.

PC 6 (knowledge about ZIKV) indicated that knowing the disease and having seen infants with microcephaly acted as a stimulator factor for the use of repellents, change of clothing and the use of screens in doors and windows. PC 7 (preventive habits) showed that pregnant women who altered their routines, avoiding leaving home or traveling to relatives’ homes to avoid greater exposure to the vector, also used repellents and worn long clothes ( Table 5 ).

DISCUSSION

At the end of 2015, the cases of congenital Zika virus syndrome in northeastern Brazil increased, which was rapidly associated with ZIKV infection during pregnancy3 , 5 . Worldwide attention has turned to this virus, which has now been seen as a public health problem for pregnant women and their newborn infants6 . The ZIKV had a greater impact in the states of Bahia, Pernambuco and Rio Grande do Norte15 , where the majority of the population is poor and the climatic conditions are more favorable to the spread of viruses transmitted by mosquitoes16 .

However, there is a shortage of epidemiological studies on the use of personal protective measures as prophylaxis for pregnant women against the Ae. aegypti bites and consequently against ZIKV infection. In the municipality of Propriá, the professional guidance in prenatal appointments of pregnant women served as motivation and stimulus for the use of repellent, change to longer clothing and information about the disease, while in Florida the awareness and prevention was promoted through billboards that defended the use of barrier protection or mosquito repellants17 .

The pregnant women in the rural area reported a higher presence of mosquitoes, due to the greater abundance of vegetation, bodies of water and wasteland or to the greater distance between the houses and consequent higher concentration of mosquitoes. Thus, the use of mosquito nets may have not aimed to avoid the sting of the ZIKV vector, but mosquito bites in general. In addition, it may be related to the low socioeconomic status and lower education level, because mosquito nets are cheaper and more durable measures18 . Although Ae. aegypti presents daytime habits8 , mosquito nets can be a great option to protect young children who spend the most part of the day in the cradle.

While the social and economic components limited the use of repellents by pregnant women in this study, about half of the women with higher income and education level in the state of Texas were concerned about the side effects that these products could cause in their children19 (even the DEET, IR3535 and Icaridin were recommended against the infection by ZIKV20 ). Although DEET is the most studied insect repellent21 , data on pregnancy use are scarce; experiments in laboratory animals did not show congenital problems with their use22 .

Pregnant women with higher education level, who received guidance from health professionals, who maintained healthy habits, who met infants with microcephaly and who had some arbovirosis in their life history changed the way they dress, using longer clothing to protect a larger body area against mosquito bites. WHO23 recommends light-colored clothing that covers as much of the body as possible (socks, long sleeves, pants or long skirts).

The change in clothing was still related to the reduction in exposure to the external environment; however, women with low social status, without the support of the partner, not only had low adherence to this measure as they were probably still obliged to leave home more often in search of their livelihood. The fact of residing in a city with warm weather also discourages the use of long clothes24 .

In the U.S. state of Texas, about a quarter of the women wore shirts or long-sleeved blouses19 . In Greece25 , country with no report of ZIKV infection, only 16% of pregnant women modified the garment, while the use of repellents reached 53%. In our study, the frequencies of 44% and 57%, respectively, suggested the use of repellents as a complementary measure for wearing long garments, because most of the women who used commercial repellents applied the product only in the arms and legs to prevent stings.

Among all the actions recommended by MH, the use of screens in doors or windows had the lowest adherence among all categories researched, especially women with low economic and social conditions, since this is an onerous measure18 .

Most pregnant women who used mosquito coils were unaware of the adverse effects of the present substances. The bedroom was the main place of use, although this type of product should be used in open areas, because it releases smoke, which can cause irritations or respiratory problems indoors26 .

In the urban area of Propriá, insecticides were more used than mechanical measures recommended by the Ministry of Health. The practicality of pyrethroid insecticides and the misinformation on toxicity contributed to the low use of screens and mosquito nets in the control of insects in households, although mechanical measures do not cause side effects17 and reduce exposure to other unwanted insects. Pyrethroid insecticides can cross the placental barrier and are known to interfere with hormonal and neurological development, in the immune system and in other physiological functions, decreasing the cephalic perimeter of the neonate, for example27 . Thus, the insecticides were used to kill insects present in the residences and prevent mosquito bites, without much distinction. Although the role of the indiscriminate household use of insecticides in the selection of resistant populations was generally neglected, its importance was recently indicated as a key factor for the failure to release Ae. aegypti infected with Wolbachia 28 .

Plug in repellents were used less frequently by pregnant women with low socioeconomic status and in rural areas. They were more used among women with higher education, who used them inside the residence in the form of tablets or refill during the night. The home products with repellent function were more used among people with lower education level and income. Commercial repellent prices in Brazil have increased due to the strong demand between 2015 and 201629 , which may have influenced the acquisition of these substances, in addition to misinformation. Alcohol- and clove-based home repellents present low cost and toxicity but have reduced protection time compared with DEET-based topical repellents30 .

The recent ZIKV epidemic in the Americas has created a large market with a variety of products for the control and avoidance of mosquitoes3 . Among them, there is citronella oil, which showed low toxicity in prenatal development in rodent tests (there are few studies in humans), but has insufficient repelling effect for adequate protection, lasting on average from three to 20 minutes31 . Citronella-containing products had no long-lasting repellent effect for any species of mosquito32 . Citronella candles and incense, reported by the pregnant women, also did not prove to have sufficient repellent effect33 .

The main guideline for the fight against ZIKV in Brazil focused on the vector as responsible for the disease and not the virus11 . Thus, all actions were aimed towards the elimination of the mosquito as a personified enemy whose elimination would solve the problem16 , with mobilization of the armed forces and task forces of cooperation and education of the population. However, considering that the infestation by Ae. aegypti has been strongly related to issues involving basic sanitation, mainly to the supply of drinking water34 , vector control strategies disconnected from the confrontation with social challenges may not be the long-term sustainable solution.

The vast majority of cases of congenital Zika syndrome have concentrated in the states of the northeast region15 , where access to water and sanitation is limited34 . Thus, the concentration of the disease is also related to the irregular and unpredictable supply of water, since the pressure of the pipes decreases depending on how far they are from the central distribution points16 . This general situation is aggravated by the region’s characteristic drought, forcing peripheral populations, without the State’s assistance, to store water. Although the ZIKV epidemic has calmed down in 2017, the transmission still persists35 and the levels of Ae. aegypti infestation remain high. The failures in the implementation of effective collective actions led to the adoption of personal protective measures, and the cost fell especially in the female population.

The images of children affected by microcephaly made women (especially the pregnant ones) the target audience of campaigns16 . Women were responsible for adopting preventive measures against Zika, while the call for male participation, if any, was minimized in the process. Thus, the burden of the responsibility fell on the women, especially those with low income, from whom the adoption of personal preventive measures and the procrastination of pregnancy were expected10 .

The ZIKV epidemic was a tragedy that largely affected women of lower socioeconomic status36 . In a period of deep economic recession in the country37 , the financial situation of pregnant women influenced the use of personal protective measures, from the cost of repellents, expenses with clothing, insecticides and other resources to the difficulty of locomotion for the health units, especially in rural areas. However, the measures of collective protection, root of the problem, continue to be neglected11 , and the population continue to be blamed for the reduction of vector transmission diseases16 . Therefore, the vector control such as Ae. aegypti and the use of individual protective measures are only some of the possible strategies to consider when dealing with ZIKV and its relationship with the birth of infants with congenital Zika syndrome. One of the most important lessons taken from this phenomenon is that social iniquity is an underlying factor for the emergence of the disease and perhaps the biggest obstacle to its elimination.

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Received: August 16, 2018; Accepted: November 23, 2018

Correspondence: Roseli La Corte Avenida Marechal Rondon, s/n Jardim Rosa Elze 49100-000 São Cristovão, SE, Brasil E-mail: rlacorte@ufs.br

Authors’ Contribution: Conception of the study: VADM, RLC. Data analysis and interpretation: VADM, RLC, JRSS. Writing of the manuscript: VADM, RLC. Critical review of the manuscript: VADM, RLC, JRSS. Approval of the final version of the manuscript: VADM, RLC.

Conflict of Interests: The authors declare no conflict of interest.

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