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Vaccuuming method as a successful strategy in the diagnosis of active infestation by Pediculus humanus capitis

ABSTRACT

Most human epidemiological and clinical studies use visual inspection of the hair and scalp to diagnose Pediculus humanus capitis , however this method has low sensitivity to diagnose active infestations (presence of nymphs and adult lice). Vacuuming the hair and scalp has been used as a diagnostic method, but there are no previous data comparing its effectiveness with visual inspection. The aim of this study was to determine the prevalence of overall infestation (nits and trophic stages), of active infestation by Pediculus humanus capitis , and to evaluate the effectiveness of vacuuming in comparison with the visual inspection. Visual inspection was performed by three examiners and vacuuming of the scalp by one investigator, with an adapted vacuum cleaner. A total of 166 children aged 4 to 10 years old were randomly selected from public schools in Southern Brazil. Considering the positive results obtained by both methods, the prevalence of overall infestation was 63.3%, whereas active infestation was 18.7%. The visual inspection was more effective on diagnosing overall infestation, however, its effectiveness to detect active infestation was lower, ranging from 0.6% (RR=3%, p<0.001) to 6.6% (RR=35%, p=0.001), depending on the number of examiners. The effectiveness of vacuuming to diagnose active infestation was higher than the one of visual inspection, with a prevalence rate of 16.3% (RR=87%, p=0.332). As presented in our study, the vacuuming method was 2.74 to 7.87 times most likely to detect active infestation, thus it could be adopted as a more accurate method to diagnose active pediculosis.

Detection; Diagnosis; Effectiveness; Hair aspiration; Head lice; Pediculosis; Pediculus humanus capitis; Prevalence; Visual inspection

INTRODUCTION

Pediculosis is a disease caused by the ectoparasite Pediculus humanus capitis (Phthiraptera: Pediculidae), known as head lice11. De Geer C. Mémories pour servir à l`historie naturelle des insectes. Stockholm: Pierre Hesselberg; 1778. p.69-82. . This parasite is an obligate blood-sucking arthropod detected on 30% to 50% of schoolchildren in Latin America22. Devera R. Epidemiología de la pediculosis capitis en América Latina. Saber. 2012;24:25-36. , 33. Amazonas PH, Souza RB, Mendes J, Moroni FT, Borges-Moroni R. Pediculose em crianças e jovens atendidos em orfanatos e ambulatório público de Manaus, AM, Brasil. Rev Patol Trop. 2015;44:207-14. . The most common symptom of pediculosis is head pruritus, however, anemia, insomnia, secondary infection may occur, as well some dermatitis caused by longstanding cases. Despite these, many low intensity infestations remain asymptomatic44. Nutanson I, Steen CJ, Schwartz RA, Janniger CK. Pediculus humanus capitis: an update. Acta Dermatovenerol Alp Pannonica Adriat. 2008;17:147-59. , 55. Cummings C, Finlay JC, MacDonald NE. Les infestations par les poux de tête: une mise à jour clinique. Paediatr Child Health. 2018;23:e25-e32. .

Most of the epidemiological and clinical studies in Latin America use the visual inspection procedure to diagnose head lice infestation22. Devera R. Epidemiología de la pediculosis capitis en América Latina. Saber. 2012;24:25-36. , 66. Borges R, Mendes J. Epidemiological aspects of head lice in children attending day care centers, urban and rural schools in Uberlandia, central Brazil. Mem Inst Oswaldo Cruz. 2002;97:189-92.

7. Catalá S, Carrizo L, Córdoba M, Khairallah R, Moschella F, Bocca JN, et al. Prevalência e intensidade da infestação por Pediculus humanus capitis em escolares de seis a onze anos. Rev Soc Bras Med Trop. 2004;37:499-501.

8. Heukelbach J, Walton SF, Feldmeier H. Ectoparasitic infestations. Curr Infect Dis Rep. 2005;7:373-80.
- 99. Mendes GG, Borges-Moroni R, Moroni FT, Mendes J. Head lice in school children in Uberlândia, Minas Gerais State, Brazil. Rev Patol Trop. 2017;46:200-8. . However, this method has shown low accuracy to detect trophic stages, like nymphs and adult lice, especially in low intensity infestations44. Nutanson I, Steen CJ, Schwartz RA, Janniger CK. Pediculus humanus capitis: an update. Acta Dermatovenerol Alp Pannonica Adriat. 2008;17:147-59. , 55. Cummings C, Finlay JC, MacDonald NE. Les infestations par les poux de tête: une mise à jour clinique. Paediatr Child Health. 2018;23:e25-e32. . Since a true positive result is determined by active pediculosis, which is acknowledged by the presence of trophic stages, many children are misdiagnosed by this method55. Cummings C, Finlay JC, MacDonald NE. Les infestations par les poux de tête: une mise à jour clinique. Paediatr Child Health. 2018;23:e25-e32. , 1010. Pollack RJ, Kiszewski AE, Spielman A. Overdiagnosis and consequent mismanagement of head louse infestations in North America. Pediatr Infect Dis J. 2000;19:689-93. , 1111. Jahnke C, Bauer E, Hengge UR, Feldmeier H. Accuracy of diagnosis of pediculosis capitis: visual inspection vs wet combing. Arch Dermatol. 2009;145:309-13. .

Other methodologies have been tested to improve the finding of active infestations, such as the combination with plastic or metal teeth head-lice comb1111. Jahnke C, Bauer E, Hengge UR, Feldmeier H. Accuracy of diagnosis of pediculosis capitis: visual inspection vs wet combing. Arch Dermatol. 2009;145:309-13.

12. Balcioglu C, Burgess IF, Limoncu ME, Şahin MT, Ozbel Y, Bilaç C, et al. Plastic detection comb better than visual screening for diagnosis of head louse infestation. Epidemiol Infect. 2008;136:1425-31.
- 1313. De Maeseneer J, Blokland I, Willems S, Vander Stichele RV, Meersschaut F. Wet combing versus traditional scalp inspection to detect head lice in schoolchildren: observational study. BMJ. 2000;321:1187-8. , a self-report diagnosis with standardized questionnaire1414. Linardi PM, Maria M, Botelho JR, Cunha HC, Ferreira JB. Pediculose capitis: prevalência em escolares da rede municipal pública de Belo Horizonte, Minas Gerais, Brasil. Mem Inst Oswaldo Cruz. 1989;84 Suppl 4:327-31. , 1515. Pilger D, Khakban A, Heukelbach J, Feldmeier H. Self-diagnosis of active head lice infestation by individuals from an impoverished community: high sensitivity and specificity. Rev Inst Med Trop Sao Paulo. 2008;50:121-2. , and the use of an vacuuming apparatus to remove the head lice more easily1616. Takano-Lee M, Edman JD, Mullens BA, Clark JM. Transmission potential of the human head louse, Pediculus capitis (Anoplura: Pediculidae). Int J Dermatol. 2005;44:811-6. , 1717. Birkemoe T, Lindstedt HH, Ottesen P, Soleng A, Næss Ø, Rukke BA. Head lice predictors and infestation dynamics among primary school children in Norway. Fam Pract. 2015;33:23-9. . The vacuum apparatus was used in a previous survey, but its efficacy was not tested1717. Birkemoe T, Lindstedt HH, Ottesen P, Soleng A, Næss Ø, Rukke BA. Head lice predictors and infestation dynamics among primary school children in Norway. Fam Pract. 2015;33:23-9. .

Therefore, the aim of this study was to evaluate the effectiveness of the vacuuming apparatus, in addition to determining the prevalence of overall pediculosis (presence of nits and trophic stages) and active pediculosis in children from cities around Curitiba, Parana State, Southern Brazil.

MATERIALS AND METHODS

Ethical standards

This study was performed in accordance with the ethical standards of the 1964 Helsiki Declaration and with the Resolution 466/2012 from the National Health Council on Ethics in Research with human beings. The study was also approved by the Research Ethics Committee of the Federal University of Parana, under registration Nº CAAE 38757614.9.0000.0102. A written informed consent was obtained from all the participants involved in the study and their legal guardians.

The study was conducted in two cities from the metropolitan area of Curitiba, Parana State, Southern Brazil: Almirante Tamandare (25º19’09”S 49º18’14”W) and Lapa (25º45’52”S 49°43’20”W). Both cities have relatively low income and medium human development index (HDI), around 0.7001818. Programa das Nações Unidas para o Desenvolvimento. Atlas do desenvolvimento humano no Brasil: árvore do IDHM. [cited 2019 Dec 18] Available from: http://www.atlasbrasil.org.br/2013/pt/arvore/municipio/anicuns_go_2010/municipio/penaforte_ce_2010/
http://www.atlasbrasil.org.br/2013/pt/ar...
. The children included in the study were 4 to 10 years old, and they studied in schools pre-selected by the educational municipal offices, based on the presence of reported pediculosis in the schools and the principal’s acceptance to participate in the study.

Diagnosis of pediculosis

To determine the existence of pediculosis infestation, each child was examined by two distinct methods. The first method was an adapted visual inspection1111. Jahnke C, Bauer E, Hengge UR, Feldmeier H. Accuracy of diagnosis of pediculosis capitis: visual inspection vs wet combing. Arch Dermatol. 2009;145:309-13. . The hair of each child was divided into four quadrants: neck, behind the ears and top of the head. The duration of the inspection (visual inspection without the aid of instruments) varied according to the hair length, lasting around 3 to 5 min. To improve the accuracy of this method, all of the children were inspected by three different examiners that were unaware of each other’s results. After the three visual examinations, each child had their head inspected by a different investigator, through a vacuuming apparatus ( Figure 1 ). This consisted of a regular vacuum cleaner (LAVOR© 1400W) adapted with a commercial voile used as a filter , inserted between the hose and the flat nozzle, to capture small particles and head lice ( Figure 1 ). The vacuuming method was performed all over the child’s head for 2 to 3 min, according to the hair length, mostly on the neck and behind the ears. After vacuuming, the filter was removed and transferred to a 47 mm Petri dish to be analyzed with a stereomicroscope under 20-40 x magnifications.

Figure 1
Vacuuming method to diagnose pediculosis: A) the vacuum apparatus (“Power Machine”) with the stickers characters to be chosen by the child; B) the voile inserted between the hose and the flat nozzle to capture head lice; C) vacuuming the head scalp; D) the voile after the vacuuming procedure.

To estimulate the voluntary participation, a “beauty salon” and a playful activity named “Power Machine” were used during the diagnostic procedure ( Figure 1 ). The “Power machine” activity consisted of parting stickers to the vacuum cleaner and, at the beginning of the procedure, the child would select and touch her favorite sticker to “gain the power” of the chosen character, than the vacuum cleaner would “pass this power” to the child while the procedure was being conducted.

The diagnosis was performed by an expert medical entomologist, based on previously published references1919. Keilin D, Nuttall GH. Iconographic studies of Pediculus humanus. Parasitology. 1930;22:1-10.

20. Stojanovich CJ Jr. The head and mouthparts of the sucking lice (Insecta: Anoplura). Microentomology. 1945;10:1-46.
- 2121. Soler Cruz M, Martin Mateo M. Scanning electron microscopy of legs of two species of sucking lice (Anoplura: Phthiraptera). Micron. 2009;40:401-8. , and the samples were classified as overall positive when any developmental stages from P. humanus capitis was detect, such as: nits, nymphs, adult, or any part of entomological evidence (hooks lice, antenna, lice molt or nits residuals)1111. Jahnke C, Bauer E, Hengge UR, Feldmeier H. Accuracy of diagnosis of pediculosis capitis: visual inspection vs wet combing. Arch Dermatol. 2009;145:309-13. , 2222. Williams LK, Reichert A, MacKenzie WR, Hightower AW, Blake PA. Lice, nits, and school policy. Pediatrics. 2001;107:1011-5. . In turn, a child was considered with active infestation when a trophic stage such as nymph or adult lice was detected; the presence of nits alone was not considered as active infestation1111. Jahnke C, Bauer E, Hengge UR, Feldmeier H. Accuracy of diagnosis of pediculosis capitis: visual inspection vs wet combing. Arch Dermatol. 2009;145:309-13. .

At the end of the study, all the participants diagnosed as positive for head lice infestation (active or overall) were referred to a health care unit. Following the diagnostic procedures, our group offered educational activities on head lice, including control measures, as part of an Extension program. Each family member received a folder with instructions regarding head lice biology and its prophylaxis, enabling the community empowerment.

Statistical analysis

Data analysis was performed by SigmaStat 3.5 program and BioEstat 5.0 program2323. Ayres M, Ayres Jr M, Ayres DL, Santos AA. BioEstat 5.0: aplicações estatísticas nas áreas das ciências biológicas e médicas. Belém; Sociedade Civil Mamirauá; 2007. . Effectiveness was obtained by the Relative Risk test (RR) and significant values were analyzed by the c 22. Devera R. Epidemiología de la pediculosis capitis en América Latina. Saber. 2012;24:25-36. test with 95% confidence interval. Odds Ratios were calculated to analyze the diagnosis likelihood of each method. Analysis of variance (ANOVA) was performed for comparisons among the examiners and the Student-Newman-Keuls post-test for multiple comparisons.

RESULTS

The survey was conducted in 166 schoolchildren, aged 4 to 10 years old, 74 girls (44.6%) and 92 boys (55.4%). The overall prevalence of pediculosis was 63.3%, while the prevalence of active infestation was 18.7% ( Table 1 ). There was no statistical difference regarding sex or the comparison of the two cities ( Table 1 ). Despite not reaching a statistical significance, according to the Odds Ratios, girls overall prevalence was 1.13 times higher than the one of the boys (64.9% versus 62.0%, respectively; c2 = 0.050, p = 0.8225). On the other hand, when looking at active infestation only, girls were 0.88 times more infested than boys (17.6% versus 19.6%; c2 = 0.762, p = 0.743) ( Table 1 ).

Table 1
Prevalence of overall and active pediculosis in schoolchildren from the Metropolitan Area of Curitiba according to the municipality and the gender.

Through visual inspection, the overall prevalence of pediculosis estimated by each examiner varied from 36.7% to 47.6% ( Table 2 ), with no statistical difference among them (H = 4.378, p = 0.112). Nonetheless, there was a significant difference when more than one examiner inspected the child’s head (H = 33.487, p<0.001) as the prevalence of overall infestation increased to 52.4%-62.7% when two or three examiners inspected the same child ( Table 2 ). There was not any difference between two and three examiners (H = 5.134, p = 0.148).

Table 2
Effectiveness of visual inspection and vacuuming methods for diagnosing pediculosis and active pediculosis in schoolchildren from the Metropolitan Area of Curitiba.

Considering the visual inspection method, a smaller number of children was diagnosed with active infestation, in comparison with the vacuuming method, and independently of the number of examiners. The prevalence of active pediculosis obtained by each examiner varied significantly from 0.6% to 4.8% (H = 6.647, p = 0.036) ( Table 2 ). When more than one examiner inspected the child’s head, the prevalence of active infestation was statistically higher in comparison with the inspection made by one examiner (H = 14.836, p = 0.022) with rates of 2.4% to 6.6% ( Table 2 ). Moreover, there was no difference in the prevalence when two and three examiners diagnosed active infestations.

Through the vacuuming method, 30.7% of the children had positive results for overall infestation and 16.3% for active infestation. Considering that by visual inspection, the highest prevalence for overall infestation was 62.7%, the visual inspection was more sensitive in detecting overall pediculosis ( Table 2 and 33. Amazonas PH, Souza RB, Mendes J, Moroni FT, Borges-Moroni R. Pediculose em crianças e jovens atendidos em orfanatos e ambulatório público de Manaus, AM, Brasil. Rev Patol Trop. 2015;44:207-14. ). Nonetheless, vacuuming was the most reliable method to diagnose active infestation, when compared to the visual inspection in all active pediculosis cases (RR = 87%, p = 0.332, Table 2 ).

Visual inspection, with two up to three examiners, was the most effective method to diagnose overall pediculosis (H = 58.465, p < 0.001). Odds Ratios showed that the visual inspection was 2.87 (two viewers) to 3.78 (three viewers) times better than vacuuming ( Table 3 ). In contrast, vacuuming was more effective in detecting active infestation (H = 58.465, p < 0.001). The Odds Ratios showed that this method is 2.74 times better in detecting trophic stages than three examiners diagnosis by visual inspection ( Table 4 ). Even though, four children diagnosed with active infestation by visual inspection were not detected by vacuuming ( Table 2 ).

Table 3
Statistical analyses (OR and p- value) showing the likelihood of the visual inspection overcoming the vacuuming regarding the overall pediculosis diagnosis.
Table 4
Statistical analyses (OR and p- value) showing the likelihood of vacuuming overcoming the visual inspection for active pediculosis diagnosis.

DISCUSSION

The present study is the first to report the pediculosis prevalence in Southern Brazil. The 63.3% overall pediculosis prevalence detected by the present study ( Table 1 ), was much higher than the national average of 24%22. Devera R. Epidemiología de la pediculosis capitis en América Latina. Saber. 2012;24:25-36. . This is one of the highest pediculosis prevalence described in the American continent, together with those obtained by combing and visual inspections in Argentina’s endemic areas (85% and 69%)2424. Chouela E, Abeldaño A, Cirigliano M, Ducard M, Neglia V, La Forgia M, et al. Head louse infestations: epidemiologic survey and treatment evaluation in Argentinean schoolchildren. Int J Dermatol. 1997;36:819-25. , 2525. Toloza AC, Laguna MF, Ortega-Insaurralde I, Vassena C, Risau-Gusman S. Insights about head lice transmission from field data and mathematical modeling. J Med Entomol. 2018;55:929-37. . Taking into consideration the active pediculosis prevalence, the 18.7% obtained in this study ( Table 1 ) was also one of the highest reported in the country2626. Heukelbach J, Winter B, Wilcke T, Muehlen M, Albrecht S, Oliveira FA, et al. Selective mass treatment with ivermectin to control intestinal helminthiases and parasitic skin diseases in a severely affected population. Bull World Health Organ. 2004;82:563-71. , 2727. Rocha EF, Sakamoto FT, Silva MH, Gatti AV. Investigação da intensidade de parasitismo, prevalência e ação educativa para controle de pediculose. Perspect Med. 2012;23:5-10. . Despite the fact that Curitiba city, Parana State capital is one of the most developed cities in the country, with a high HDI (0.8 to 1); there are less developed municipalities in its surrounding1818. Programa das Nações Unidas para o Desenvolvimento. Atlas do desenvolvimento humano no Brasil: árvore do IDHM. [cited 2019 Dec 18] Available from: http://www.atlasbrasil.org.br/2013/pt/arvore/municipio/anicuns_go_2010/municipio/penaforte_ce_2010/
http://www.atlasbrasil.org.br/2013/pt/ar...
, like the cities included in this survey.

The comb method is 2 to 4 times faster and more effective to diagnose active pediculosis than the visual inspection method1111. Jahnke C, Bauer E, Hengge UR, Feldmeier H. Accuracy of diagnosis of pediculosis capitis: visual inspection vs wet combing. Arch Dermatol. 2009;145:309-13. , 1313. De Maeseneer J, Blokland I, Willems S, Vander Stichele RV, Meersschaut F. Wet combing versus traditional scalp inspection to detect head lice in schoolchildren: observational study. BMJ. 2000;321:1187-8. , 2828. Mumcuoglu KY, Friger M, Ioffe-Uspensky I, Ben-Ishai F, Miller J. Louse comb versus direct visual examination for the diagnosis of head louse infestations. Pediatr Dermatol. 2001;18:9-12. , however, its acceptance can be low by children and parents who may complain about embarrassment, tedious, time-consuming and physical discomfort2929. Gordon SC. Shared vulnerability: a theory of caring for children with persistent head lice. J Sch Nurs. 2007;23:283-92. . In the present study, we chose not to use the comb method because most children from the community have dense and curly hair and would complain about combing as being “painful” and an embarrassing procedure. Thus, we used another methodology, the vacuuming method, and added a playful activity3030. Coscrato G, Pina JC, Mello DF. Utilização de atividades lúdicas na educação em saúde: uma revisão integrativa da literatura. Acta Paul Enferm. 2010;23:257-63. to it, to increase the acceptance by children and the approval by their parents.

The prevalence of overall infestation in girls observed at the present study is similar to the reported ones in other studies from Brazil and other countries99. Mendes GG, Borges-Moroni R, Moroni FT, Mendes J. Head lice in school children in Uberlândia, Minas Gerais State, Brazil. Rev Patol Trop. 2017;46:200-8. , 1717. Birkemoe T, Lindstedt HH, Ottesen P, Soleng A, Næss Ø, Rukke BA. Head lice predictors and infestation dynamics among primary school children in Norway. Fam Pract. 2015;33:23-9. , 3131. Moosazadeh M, Afshari M, Keianian H, Nezammahalleh A, Enayati AA. Prevalence of head lice infestation and its associated factors among primary school students in Iran: a systematic review and meta-analysis. Osong Public Health Res Perspect. 2015;6:346-56. . The differences between sex may be associated to behavioral variations66. Borges R, Mendes J. Epidemiological aspects of head lice in children attending day care centers, urban and rural schools in Uberlandia, central Brazil. Mem Inst Oswaldo Cruz. 2002;97:189-92. . However, this behavioral variation may not be considered when taking into consideration the active infestation, as in the present study there was not a statistical difference between the prevalence of active infestation in boys and girls ( Table 1 ). Considering that the empty nit can remain attached to the hair as long as six months after the infestation44. Nutanson I, Steen CJ, Schwartz RA, Janniger CK. Pediculus humanus capitis: an update. Acta Dermatovenerol Alp Pannonica Adriat. 2008;17:147-59. , the finding of an empty nit could result in a false positive for head lice infestation, mainly in children with long hair1010. Pollack RJ, Kiszewski AE, Spielman A. Overdiagnosis and consequent mismanagement of head louse infestations in North America. Pediatr Infect Dis J. 2000;19:689-93. , 1919. Keilin D, Nuttall GH. Iconographic studies of Pediculus humanus. Parasitology. 1930;22:1-10. , 2525. Toloza AC, Laguna MF, Ortega-Insaurralde I, Vassena C, Risau-Gusman S. Insights about head lice transmission from field data and mathematical modeling. J Med Entomol. 2018;55:929-37. . Considering that, this difference may be more related to hair length than to sex ratio66. Borges R, Mendes J. Epidemiological aspects of head lice in children attending day care centers, urban and rural schools in Uberlandia, central Brazil. Mem Inst Oswaldo Cruz. 2002;97:189-92. , 99. Mendes GG, Borges-Moroni R, Moroni FT, Mendes J. Head lice in school children in Uberlândia, Minas Gerais State, Brazil. Rev Patol Trop. 2017;46:200-8. .

In the present study, it was observed that at least two examiners are optimal to validate the diagnosis by the visual inspection method ( Table 3 ). Considering the Odds Ratio test, two examiners are 1.66 times more likely to detect overall infestation in schoolchildren than only one examiner (p = 0.028, Table 3 ). However, when only active infestation was considered, this difference was not significant (p = 0.378, Table 4 ). The diagnosis conducted by two examiners has already being reported, however these studies did not measure the agreement between the examiners88. Heukelbach J, Walton SF, Feldmeier H. Ectoparasitic infestations. Curr Infect Dis Rep. 2005;7:373-80. , 1313. De Maeseneer J, Blokland I, Willems S, Vander Stichele RV, Meersschaut F. Wet combing versus traditional scalp inspection to detect head lice in schoolchildren: observational study. BMJ. 2000;321:1187-8. , 1919. Keilin D, Nuttall GH. Iconographic studies of Pediculus humanus. Parasitology. 1930;22:1-10. . Nonetheless, in the present study, the effectiveness of visual inspection in detecting active infestation did not surpass 40% considering all the positive cases (RR = 35%, Table 2 ), which was similar to other studies1111. Jahnke C, Bauer E, Hengge UR, Feldmeier H. Accuracy of diagnosis of pediculosis capitis: visual inspection vs wet combing. Arch Dermatol. 2009;145:309-13. , 1515. Pilger D, Khakban A, Heukelbach J, Feldmeier H. Self-diagnosis of active head lice infestation by individuals from an impoverished community: high sensitivity and specificity. Rev Inst Med Trop Sao Paulo. 2008;50:121-2. . The number of positive cases for active infestation is lower because trophic stages can avoid light and use camouflage, making it hard to identify them on the head by visual inspection1919. Keilin D, Nuttall GH. Iconographic studies of Pediculus humanus. Parasitology. 1930;22:1-10. , 2828. Mumcuoglu KY, Friger M, Ioffe-Uspensky I, Ben-Ishai F, Miller J. Louse comb versus direct visual examination for the diagnosis of head louse infestations. Pediatr Dermatol. 2001;18:9-12. , 3232. Frankowski BL, Bocchini JA. Head lice. Pediatrics. 2010;126:392-403. .

Visual inspection seems to be the method of choice in Brazilian researches as most of the previously published work used it to detect active pediculosis1515. Pilger D, Khakban A, Heukelbach J, Feldmeier H. Self-diagnosis of active head lice infestation by individuals from an impoverished community: high sensitivity and specificity. Rev Inst Med Trop Sao Paulo. 2008;50:121-2. , 2626. Heukelbach J, Winter B, Wilcke T, Muehlen M, Albrecht S, Oliveira FA, et al. Selective mass treatment with ivermectin to control intestinal helminthiases and parasitic skin diseases in a severely affected population. Bull World Health Organ. 2004;82:563-71. , 2727. Rocha EF, Sakamoto FT, Silva MH, Gatti AV. Investigação da intensidade de parasitismo, prevalência e ação educativa para controle de pediculose. Perspect Med. 2012;23:5-10. . However, even if the result is obtained by different examiners, this method usually overestimate the number of positive cases, as the examiners consider empty nits as an indicative of active infestation, and they often fail to distinguish between active and past infestation1010. Pollack RJ, Kiszewski AE, Spielman A. Overdiagnosis and consequent mismanagement of head louse infestations in North America. Pediatr Infect Dis J. 2000;19:689-93.

11. Jahnke C, Bauer E, Hengge UR, Feldmeier H. Accuracy of diagnosis of pediculosis capitis: visual inspection vs wet combing. Arch Dermatol. 2009;145:309-13.
- 1212. Balcioglu C, Burgess IF, Limoncu ME, Şahin MT, Ozbel Y, Bilaç C, et al. Plastic detection comb better than visual screening for diagnosis of head louse infestation. Epidemiol Infect. 2008;136:1425-31. , 2828. Mumcuoglu KY, Friger M, Ioffe-Uspensky I, Ben-Ishai F, Miller J. Louse comb versus direct visual examination for the diagnosis of head louse infestations. Pediatr Dermatol. 2001;18:9-12. . Thus, the children diagnosed as positive by the visual inspection may be treated unnecessarily, missing school days, and their parents missing working days33. Amazonas PH, Souza RB, Mendes J, Moroni FT, Borges-Moroni R. Pediculose em crianças e jovens atendidos em orfanatos e ambulatório público de Manaus, AM, Brasil. Rev Patol Trop. 2015;44:207-14. , 1010. Pollack RJ, Kiszewski AE, Spielman A. Overdiagnosis and consequent mismanagement of head louse infestations in North America. Pediatr Infect Dis J. 2000;19:689-93. , 1313. De Maeseneer J, Blokland I, Willems S, Vander Stichele RV, Meersschaut F. Wet combing versus traditional scalp inspection to detect head lice in schoolchildren: observational study. BMJ. 2000;321:1187-8. , 1919. Keilin D, Nuttall GH. Iconographic studies of Pediculus humanus. Parasitology. 1930;22:1-10. .

Several reports show that a lack of basic knowledge and many myths regarding pediculosis are frequent among school communities3333. Magalhães KP, Silva JB. A infestação por pediculose e o ensino de saúde. Rev Saude Pesq. 2012;5:408-16.

34. Cunha PV, Pinto ZT, Liberal EF, Barbosa JV. O discurso dos professores sobre a transmissão da pediculose. Rev Bras Crescimento Desenvolv Hum. 2008;18:298-307.
- 3535. Sangaletti V, Santos R, Bosa C, Klisiowicz DR. Percepção dos professores dos CMEIs da Matriz sobre a pediculose humana. Rev Teoria Prat Educ. 2018;18:9-14. . The major problem pointed by these reports was the misunderstanding on how head lice are transmitted and treated. Another concern is the embarrassment among parents of infested children, which interfere with the management of this medical condition2929. Gordon SC. Shared vulnerability: a theory of caring for children with persistent head lice. J Sch Nurs. 2007;23:283-92. . There is not a public program directed to the control of head lice in both regions studied, thus the creation of permanent educational programs, associated with the correct diagnosis, may help to reduce the prevalence of active pediculosis in schoolchildren99. Mendes GG, Borges-Moroni R, Moroni FT, Mendes J. Head lice in school children in Uberlândia, Minas Gerais State, Brazil. Rev Patol Trop. 2017;46:200-8. , 3434. Cunha PV, Pinto ZT, Liberal EF, Barbosa JV. O discurso dos professores sobre a transmissão da pediculose. Rev Bras Crescimento Desenvolv Hum. 2008;18:298-307. , 3535. Sangaletti V, Santos R, Bosa C, Klisiowicz DR. Percepção dos professores dos CMEIs da Matriz sobre a pediculose humana. Rev Teoria Prat Educ. 2018;18:9-14. .

This was the first study comparing vacuuming with visual inspection in the diagnosis of head lice. In the present study, the prevalence of active pediculosis obtained by vacuuming was significantly higher (RR = 87%, Table 2 ) than visual inspection. Other studies have described that the vacuum cleaner is efficient to remove head lice from carpets and fomites1616. Takano-Lee M, Edman JD, Mullens BA, Clark JM. Transmission potential of the human head louse, Pediculus capitis (Anoplura: Pediculidae). Int J Dermatol. 2005;44:811-6. , and it has been already used to detect active pediculosis in schoolchildren, but vacuuming was not compared to other methods1717. Birkemoe T, Lindstedt HH, Ottesen P, Soleng A, Næss Ø, Rukke BA. Head lice predictors and infestation dynamics among primary school children in Norway. Fam Pract. 2015;33:23-9. .

Our results show that vacuuming was the best method to detect active pediculosis ( Table 4 ). However, four children diagnosed with living lice, by visual inspection, were not diagnosed as positive by the vacuuming ( Table 2 ). This could have occurred because the visual inspection (with removal of the living louse, owing to ethical reasons) was conducted prior to the vacuuming exam or due to mishandling by the researcher that performed the vacuum method. Thus, if the head lice were not removed during the visual inspection, those children would probably have been properly diagnosed by the vacuuming.

There is no previously published data comparing the vacuuming and the visual inspection methods. The vacuuming showed to be 7.87 times better to detect active infestation than the visual inspection made by one examiner (p<0.001, Table 4 ). There is not a study comparing the comb method with the vacuuming method to diagnose active pediculosis, so that new studies are necessary to determine what methodology is the most effective. As the effectiveness of the vacuuming method and its acceptance associated with the playful activity was high, it could be used by educational and health offices as the standard method to diagnose active pediculosis, to improve public health and to reduce the prevalence of active pediculosis in schoolchildren.

ACKNOWLEDGMENTS

We thank the undergraduate students Valéria Mendes Soares, Raquel Vizzotto de Menezes, Raymundo Seguí López-Peñalver and Lourdes Mengual Sanches and the laboratory assistant Eliana Maura Leite, for their assistance during the diagnostic procedures and their collaboration with the Extension program and educational activities.

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  • FINANCIAL SUPPORT
    This research was funded by UFPR Office for Extension and Culture (PROEC) and by the Brazilian Extension Program for Universities (ProExt). Scholarship from UFPRTesouro Nacional and Araucária Foundation (to Lustosa BPR), CAPES (to Haidamak J, Oishi CY, Souza AB and Lima BJFS), and National Counsel of Technological and Scientific Development, Brasilia, Brazil, for fellowship (Vicente VA).

Publication Dates

  • Publication in this collection
    07 Feb 2020
  • Date of issue
    2020

History

  • Received
    26 Aug 2019
  • Accepted
    17 Dec 2019
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