The Reliability of Videomicroscopic Compared with Skin Scraping

Microscopic Examination in Detection of Sarcoptes Scabiei

Merlina Juhendy

, Yulia Farida Yahya

, Inda Astri Aryani

, Legiran

Department of Dermatology and Venereology Faculty of Medicine Sriwijaya University/Dr. Moh. Hoesin

General Hospital Palembang, Jendral Sudirman Street Km 3.5, Palembang, South of Sumatera, Indonesia

Department of Anatomy, Faculty of Medicine Sriwijaya University, Dr. Mohammad Ali Street, Palembang,

South of Sumatera, Indonesia

Keyword: scabies, Sarcoptes scabiei, microscopic, videomicroscope, reliability

Abstract: Scabies is a contagious skin disease due to infestation of Sarcoptes scabiei var. hominis (S. scabiei). Skin

scraping microscopic examination is a standard diagnostic procedure, which is still considered as a “gold

standard” to confirm the diagnosis. This method is invasive, time consuming with risks associated

procedure. Videomicrosc1ope, a non medical digital microscope that can be used to visualize burrow, mites

and eggs of S. scabiei. The reliability of videomicroscope to detect mites has not been studied. This study is

to determine reliability of videomicroscope and skin scraping microscopic examination in detection of S.

scabiei in presumptive scabies patients.This is a diagnostic test study which was conducted from August to

October 2017 at the Orphanage Subulussalam, Orphanage Al-Wiam, Lembaga Wanita Peduli Sriwijaya,

Lembaga Pendidikan dan Sosial Pemuda Bersatu and Lembaga Perlindungan Anak Kota Palembang. A

total of 139 presumptive scabies patients who met the inclusion and exclusion criteria were recruited by

consecutive sampling. All subjects were examined with blinded method using videomicroscope and skin

scraping microscopic examination by researcher and other examiner. S. scabiei mites that was detected by

skin scraping examination was 49,6% of all subject study. Sensitivity and specificity of videomicroscope

examination compared to skin scraping microscopic examination were 89,8% and 82,9%. (PPV 83,8%;

NPV 89,2%; positive likelihood ratio 4,57; negative likelihood ratio 0,16; accuracy 86,3%, AUC 0,864).

Videomicroscope showed high sensitivity and specificity, which was useful as a rapid alternative diagnostic

method to detect S. scabiei in high risk population.

1 INTRODUCTION

Scabies is a skin disease due to infestation of

Sarcoptes scabiei var. hominis (S. scabiei) as an

obligate parasite on the epidermis (Burkhart and

Burkhart, 2012). Clinical manifestation of scabies are

skin lesions accompanied by pruritus due to allergic

reaction or inflammation to the mites and their

products, it can resemble to other diseases

(Chosidow, 2006). This can cause a misdiagnosis, an

inadequate therapy, also can increase the risk of

bacterial infection and morbidity, so further

examination is needed to confirm the diagnosis

(Heukelbach et al., 2013; Micali et al., 2016).

Standard diagnostic procedures to confirm the

diagnosis is microscopic examination of skin

scraping (SS). This examination method is invasive

and some literatures considered it as a “gold

standard” for definite diagnosis by the visualization

of the mites, eggs or scybala (Leung and Miller,

2011; PERDOSKI, 2017). Few disadvantadges of

microscopic examination by skin scraping are a pain

that cause discomfort especially in younger patients,

a risk of bleeding, a secondary bacterial infection, a

necessary to be repeated on a few locations and a

time consuming (Micali et al., 2016; Anderson and

Strowd, 2017).

Recently there is a new non invasive technique

such as a videomicroscope (VM), a digital

microscope with magnification until 1000x allowing

direct visualization burrow, mites and eggs of S.

scabiei for a definite diagnosis of scabies, faster and

more practical in its use, with affordable price

(Lacarrubba et al., 2015; Micali et al., 2015).

The objective of this study is to determine the

reliability of VM compared with SS microscopic

276

Juhendy, M., Yahya, Y., Aryani, I. and Legiran, .

The Reliability of Videomicroscopic Compared with Skin Scraping Microscopic Examination in Detection of Sarcoptes Scabiei.

DOI: 10.5220/0008155602760280

In Proceedings of the 23rd Regional Conference of Dermatology (RCD 2018), pages 276-280

ISBN: 978-989-758-494-7

examination to detect S. scabiei in presumptive

scabies patients.

2 METHODS

This is a diagnostic test study with cross sectional

design from August to October 2017 at the

Orphanage Subulussalam, Orphanage Al-Wiam,

Lembaga Wanita Peduli Sriwijaya, Lembaga

Pendidikan dan Sosial Pemuda Bersatu and

Lembaga Perlindungan Anak Kota Palembang in

Palembang. The study was approved by the ethics

committee. A total of 139 patients with skin disease

who met the inclusion and exclusion criteria were

recruited by consecutive sampling. The inclusion

criteria was presumptive scabies patients, who

agreed to participate in the study. Exclusion criteria

was patient who had been treated with scabies

therapy within 4 weeks prior to study. Demographic

data were collected and all subjects were blinded

examined using VM and SS microscopic

examination by researcher and other examiner.

3 RESULTS

In this study majority of the subjects were male with

ratio of male is 52,5% and female is 47,5%. The

subjects of this study were divided into few groups

based on age which they were infants (3,6%),

children (31,7%), adolescents (61,2%) and adults

(3,6%). The education level of the subjects was

divided into 4 groups: non-school (12,2%), primary

school (28,8%), junior high (37,2%) and senior high

school (21,6%).

Table 1. Demographic and characteristic of the lesions

Characteristic Total (n) Percentage (%)

Gender

Male

Female

52,5

47,5

Age

Infants

Children

Adolescents

Adult

3,6

31,7

61,2

3,6

Education

Non school

Primary school

Junior high school

Senior high school

12,2

28,8

37,4

21,6

Sharing clothes/towels together

Sharing bed with others

Number of people in a bedroom

1 person

2-3 persons

4-5 persons

>5 persons

101

53,2

72,7

7,9

25,2

30,9

Location of the lesions

Interdigitalis manus

Radiocarpalisjoint

Dorsum manus

Antecubiti

Flexor extremitas superior

Abdominalis(umbilicus/periumbilicus)

Inguinalis/genitalia

Glutealis

125

102

106

89,9

73,4

76,3

6,5

31,7

20,1

31,7

20,9

Location where S. scabiei mites detected

7,2

orsum manus

lexor extremitas superio

7,2

Glutealis 2

2.9

nguinalis

enitalia 5

7,2

nterdigitalis manus 35

50,7

Abdominalis 4

5,7

adiocarpalis join

18,8

The Reliability of Videomicroscopic Compared with Skin Scraping Microscopic Examination in Detection of Sarcoptes Scabiei

277

Study subjects 53,2% were sharing

clothes/towels together with friends. A total of 36%

of the study subjects had 2-3 friends in one room

and 72,7% of the study subjects occupied the bed

with others. The most common lesions were

erythematous papules (99,3%) and most lesions

were found on the interdigital region (89,9%).

The total of S. scabiei detected using

microscopic skin scraping examination in this study

was 49,6% of all study subjects, with the most

commonly location found is on interdigital manus

(28,8%). Kappa value of VM examination between

two examiners was 0,82. The analysis of VM

examination results compared to SS microscopic

examination as a "gold standard" was obtained by

Sn, Sp VM value were 89,8% and 82,8% (PPV

83,8%, NPV 89,2%, PLR 5,25, NLR 0,12, 86,3% of

accuracy and AUC 0,864).

4 DISCUSSION

Scabies is a parasitic infestation of the skin caused

by S. scabiei, highly contagious through both direct

and indirect contact and affect all ages, races and

socioeconomic levels (Burkhart and Burkhart,

2012). Scabies is a global public health problem,

which is often overlooked, according to the WHO

including one "neglected tropical diseases". In poor

communities scabies potentially causing outbreaks

associated with its transmission method,

overcrowding, poor sanitation and low knowledge

(Heukelbach and Feldmeier, 2006). Non-specific

clinical features may lead to misdiagnosis and may

be a source of active transmission (Hewitt et al.,

2015). Late treatment and inadequate therapy,

increasing the risk of bacterial infections and

morbidity, so a diagnostic tool with high sensitivity

is needed (Micali et al., 2016). According to the

Japanese dermatological guidelines for diagnosis

and treatment 2017 the sensitivity of SS microscopic

examination varies between 10-70% (Ishii et al.,

2017). Dupuy et al. found that diagnosis of scabies

only on clinical grounds, because of the difficulty of

detecting S. scabiei mites, causing 27% of untreated

scabies patients, thus increasing the risk for an

outbreak of scabies. Videomicroscope is a non

medical digital microscope, commonly used for

botanical, entomology and microelectronics, that can

be used to make a definite diagnosis of scabies

(Micali et al., 2016; Anderson and Strowd, 2017).

The analysis of VM diagnostic test result compared

to SS microscopic examination as 'gold standard'

obtained by Sn and Sp VM were 89.9% and 82.9%

(PPV 83,8%; NPV 89,2%; PLR 4,57; NLR 0.16 and

86.3% accuracy, AUC 0.864). In this study of 139

patients (49.6%) presumptive scabies detected mites,

S. scabiei eggs in 69 patients. According to Micalli,

et al study 20 presumptive scabies patients were

examined using VM, VD was confirmed by SS

microscopic examination, S. scabiei mites were

detected in 15 patients, during follow-up 5 patients

remained negative. In the study, the VM diagnostic

test was not performed, and sample size population

were small (Lacarrubba et al., 2015; Micali et al.,

2015).

Burrow is scabies pathognomonic lesion, that

often can be difficult to find, especially in the

tropical climates, but VM can help to visualize it

(Walton and Currie, 2007; Burkhart and Burkhart,

2012).

Table 2. Diagnostic value results of VM compared with SS microscopic examination

No. Diagnostic test Value CI (95%)

1. Sensitivity 89,9% 87,5-90,5

2. Specificity 82,9% 81,5-84,3

3. Accurac

86,3% 84,9-87,7

4. Positive likelihood ratio 5,25 5,1-5,3

egative likelihood ratio 0,13 0,11-0,15

6. Positive

redictive value 83,8% 82,4-85,2

Negative predictive value

rea under curve

89,2%

0,864

87,7-90,7

0,797-0,930

A good accuracy rate of VM (86.3%) also

reduces the risk of misdiagnosis so as to prevent

outbreaks of scabies especially in densely populated

and socioeconomic areas. VM examination is a non

invasive method, it can be well tolerated and

efficient in terms of time because it only takes ≤10

minutes to direct visualization of S. scabiei mites,

eggs. and burrows and may be used for the follow up

evaluation after therapy (Lacarrubba et al., 2010).

Further study is needed in multicenter with larger

sample size and more heterogeneous populations to

determine the reliability VM in the detection of S.

scabiei.

RCD 2018 - The 23rd Regional Conference of Dermatology 2018

278

Figure 1. Videomicroscopic examination clearly evident the burrow (black arrow) and S. scabiei mite (blue arrow).

5 CONCLUSION

Videomicroscope has diagnostic value with high

accuracy and high level of accordance between the

examiners. The value of VM examination were:

sensitivity 89.9%, specificity 82.9%, PPV 83.8%,

89.2% NPV and 86.3% accuracy, AUC 0.864. Based

on this, VM diagnostic values are as good as SS

microscopic examination. Videomicroscope can be

used as a means of prevention of scabies in areas

with inaccessible and densely populated

communities.

ACKNOWLEDGEMENT

The authors would like to thank the Department of

Dermatology and Venereology, and Faculty of

Medicine of Sriwijaya University and all those who

assist in the effort of this research.

REFERENCES

Anderson, K.L., Strowd, L.C., 2017. Epidemiology,

Diagnosis, and Treatment of Scabies in a Dermatology

Office. The Journal of the American Board of

Family Medicine 30, 78–84.

doi:10.3122/jabfm.2017.01.160190

Burkhart, C.N., Burkhart, C.G. 2012. Scabies, other mites

and pediculosis. In: Goldsmith LA, Katz SI, Gilchrest

BA, Paller AS, Leffel DJ, Wolff K. eds. Fitzpatrick's

Dermatology in General Medicine 8

ed. Mc Graw-

Hill, New York Chicago pp. 2569-72

Chosidow, O., 2006. Scabies. New England Journal of

Medicine 354, 1718–1727.

doi:10.1056/NEJMcp052784

Dupuy, A., Dehen, L., Bourrat, E., Lacroix, C.,

Benderdouche, M., Dubertret, L., Morel, P., Feuilhade

de Chauvin, M., Petit, A., 2007. Accuracy of standard

dermoscopy for diagnosing scabies. Journal of the

American Academy of Dermatology 56, 53–62.

doi:10.1016/j.jaad.2006.07.025

Heukelbach, J., Feldmeier, H., 2006. Scabies. Lancet.

doi:10.1016/S0140-6736(06)68772-2

Heukelbach, J., Mazigo, H.D., Ugbomoiko, U.S., 2013.

Impact of scabies in resource-poor communities.

Current Opinion in Infectious Diseases.

doi:10.1097/QCO.0b013e32835e847b

Hewitt, K.A., Nalabanda, A., Cassell, J.A., 2015. Scabies

outbreaks in residential care homes: Factors associated

with late recognition, burden and impact. A mixed

methods study in England. Epidemiology and Infection

143, 1542–1551. doi:10.1017/S0950268814002143

Ishii, N., Asai, T., Asahina, A., Ishiko, A., Imamura, H.,

Kato, T., … Wada, Y., 2017. Guideline for the

diagnosis and treatment of scabies in Japan (third

edition): Executive Committee of Guideline for the

Diagnosis and Treatment of Scabies. Journal of

Dermatology,44(9), 991–1014.

https://doi.org/10.1111/1346-8138.13896

Lacarrubba F, Verzì AE, Micali G. 2015. A controlled,

dermatologist independently assessed, noninferiority

clinical trial of high resolution medically marketed

videodermatoscopy versus low cost nonmedical

videomicroscopy for the diagnosis of scabies. Journal

of the American Academy of Dermatology.

doi:10.1016/j.jaad.2015.02.510

Lacarrubba, F., D’Amico, V., Nasca, M.R., Dinotta, F.,

Micali, G., 2010. Use of dermatoscopy and

videodermatoscopy in therapeutic follow-up: A

review. International Journal of Dermatology.

doi:10.1111/j.1365-4632.2010.04581.x

The Reliability of Videomicroscopic Compared with Skin Scraping Microscopic Examination in Detection of Sarcoptes Scabiei

279

Leung, V., Miller, M., 2011. Detection of scabies: A

systematic review of diagnostic methods. The

Canadian journal of infectious diseases & medical

microbiology 22, 143–146.

Micali, G., Lacarrubba, F., Verzì, A.E., Chosidow, O.,

Schwartz, R.A., 2016. Scabies: Advances in

Noninvasive Diagnosis. PLoS Neglected Tropical

Diseases. doi:10.1371/journal.pntd.0004691

Micali, G., Lacarrubba, F., Verzì, A.E., Nasca, M.R.,

2015. Low-cost equipment for diagnosis and

management of endemic scabies outbreaks in

underserved populations. Clinical Infectious Diseases.

doi:10.1093/cid/ciu826

PERDOSKI. 2017. Panduan Layanan Klinis Dokter

Spesialis Dermatologi dan Venereologi. Jakarta. pp

80-83

Walton, S.F., Currie, B.J., 2007. Problems in diagnosing

scabies, a global disease in human and animal

populations. Clinical Microbiology Reviews.

doi:10.1128/CMR.00042-06

RCD 2018 - The 23rd Regional Conference of Dermatology 2018

280