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Background: Indonesia has the third-highest leprosy prevalence, and the transmission continues. Objectives: the present study aimed to describe some of the characteristics of leprosy contacts, such as the profile of the serological antibody IgM anti-PGL-1, socioeconomic factors, environmental factors, and behavioral factors. Materials and Methods. We conducted a cross-sectional study involving 77 leprosy contacts from an endemic area in Winongan, Pasuruan, East Java, Indonesia. The households or neighbors of the leprosy case recorded at Winongan Health Center, voluntarily participated in this study. Informed consent was obtained before starting the study. Three of them were excluded because they showed skin lesions as leprosy symptoms. Serum samples were assayed for IgM antibodies PGL-1 titers using enzyme-linked immunosorbent assay (ELISA). The questionnaire was used to collect information about demographic, socioeconomic, environmental, and behavioral aspects of contact. The data were analyzed descriptively using Fisher’s Exact Test. Results. Of 74 contacts, all of them were contacts of MB cases, and 6 (8.11%) were seropositive, with a cut-off point ≥ 605 ug/ml. Although none of the contact characteristics were significantly associated with IgM anti-PGL-1 seropositivity, potential risk markers and indirect transmission of leprosy were identified, including 56.76% manual labor, 90.54% living in poverty, 83.78% drinking from unprotected springs, only 20.27% boiling water to drink, and 48.65% bathing in open water bodies. Conclusions. The seropositivity among contacts, especially perimeter contacts, may identify potential active infection and transmission of leprosy in this population. Identified potential risk markers of leprosy should be noticed for prevention programs supporting leprosy elimination.

Leprosy remains a public health problem in Indonesia. Diagnostic tools have been developed in order to aid early diagnosis and prompt treatment. Phenolic glycolipid (PGL)-1 has been considered as a good candidate for leprosy diagnosis but has been found to have several limitations. More recently, the conjugation between natural disaccharide octyl (NDO) and leprosy IDRI diagnostic (LID)-1, known as NDO-LID, shows great promise because of its high specificity and sensitivity and its ability to detect leprosy before any clinical signs are present. The test incorporates the detection of IgM antibodies towards NDO and IgG antibodies towards LID-1. This study aimed to show the profile of IgM, IgG, and IgAMG antibody titers against NDO-LID to further discover its diagnostic potential. Sera from eight new leprosy patients from Surabaya, Indonesia were evaluated using ELISA detecting levels of IgG, IgM and IgAMG antibodies against NDO-LID antigen. Skin slit biopsy was also taken for smear and histopathology test. This study shows that the titer levels IgAMG anti NDO-LID were consistent with the results from smear and were consistently higher compared to IgM or IgG titer alone. IgAMG might have the potential to improve the sensitivity of NDO-LID serologic tests but further investigation is needed.

The high prevalence among children shows continued transmission from adult and lack of disease control by the health system. Detection of anti-NDO-LID-1 has been known to be more effective to predict the development of leprosy in household contacts than just detecting PGL-1 or LID- 1 alone. However, serodiagnosis is not available in poorer-settings area and the procedure (venepuncture) is still inconvenient to some people. These problems can be solved by using finger-prick blood sample on filter paper. This study aims to prove the effectiveness of using capillary blood samples on filter paper to detect the positivity of Ig G antibody against NDO-LID-1 antigen in asymptomatic household contacts. Seventeen samples of capillary blood on filter paper and sera were tested for IgG anti-NDO-LID-1 using ELISA. There was no significant difference between IgG level from filter paper and serum (p=0.754) and there was also a strong positive correlation (R=0.906) between the two procedures. These findings show that the use of filter paper and NDO-LID-1 is worthy of further investigations, especially for those with lower bacillary load or contacts of leprosy patients.

Delays of leprosy detection and treatment can lead to disability and potential transmission. Serologic examination has the advantage in detecting Subclinical Leprosy. The procedure of serologic test, which is one of its main limitation, could be simplified by the use filter paper. This study aims to assess the effectiveness of the use of capillary blood dropped on filter paper as a substitute for venous blood in household contact of leprosy patients. Seventeen samples of capillary blood dried on filter paper and venous blood samples from the same individual were examined by ELISA method to determine the levels of IgM anti-Phenolic glycolipid-1 (PGL-1). The mean of anti- PGL-1 IgM levels of filter paper samples 163.31±126.16; whereas the mean of levels from venous samples was 473.16±411.26. There was significant difference and correlation between these two groups. Samples on filter paper in household contact can be used to determine the level of anti-PGL-1 IgM in serum by converting on the regression basis. Further study is required to evaluate the potency of filter paper methods to conduct large-scale serological screening.