Role of Leishmanin Skin Test (LST) as Epidemiological Indicators for Cutaneous Leishmaniasis in Al-tragma Village, River Nile State, Sudan

Background Cutaneous Leishmaniasis (CL) is a common health problem in the world and the zoonotic form reported to occur in Sudan. Leishmaniasis has been considered the second parasitic health problem after malaria. Therefore we determine the role of Leishmanin Skin Test (LST) as epidemiological indicators for CL infection in Al-tragma village; one of the endemic areas for the disease in Sudan. Methods The study is a cross-sectional study, 410 individuals inhabiting Al-tragma village were enrolled in the study. Two methods used in this study; structure questionnaire and LST. A structured questionnaire was designed to collect and tested socio-demographic characteristics. The LST was performed by intradermal injection of 0.1 ml LST antigen on the volar surface of the left forearm. The result of LST was read after 48–72 hours using the ballpoint pen technique. SPSS (v 20.0) was used for data analysis. Results LST results showed that 70.7% of respondents were positive and 29.3% were negative. The most infected age groups were 31–40 years (80%) and more than 40 years (82%). The result showed there was a significant difference between LTS and age groups, occupation, domestic and pets animals found in and around the houses, and those having the disease before (P-value < 0.05). Conclusion The overall positive rate for LST was (70.7%). The exposure duration had no effect on LST results. It seems that those patients acquired long-lasting immunity. LST is still a promising tool to evaluate the epidemiological status in endemic areas.

A review of the leishmanin skin test: A neglected test for a neglected disease

The leishmanin skin test (LST) has been used for decades to detect exposure and immunity to the parasite Leishmania, the causative agent of the neglected tropical disease leishmaniasis. In the LST, Leishmania antigen (leishmanin) is intradermally injected into the forearm. In an individual who has been previously infected, a delayed-type hypersensitivity (DTH) reaction results in a measurable induration at the site of the injection, indicating that previous exposure to Leishmania has resulted in the development of cell-mediated immunity. LST positivity is associated with long-lasting protective immunity against reinfection, most notably as reported for visceral leishmaniasis (VL). Despite efforts over the past few decades, leishmanin antigen is no longer produced under good manufacturing practice (GMP) conditions anywhere in the world. Consequently, the use of the LST in epidemiological studies has declined in favor of serological and molecular tests. In this review, we provide a historical overview of the LST and justification for the reintroduction of leishmanin. A GMP-grade leishmanin can be used to detect immunity in vivo by the LST and can be investigated for use in an interferon-γ release assay (IGRA), which may serve as an in vitro version of the LST. The LST will be a valuable tool for surveillance and epidemiological studies in support of the VL elimination programs and as a surrogate marker of immunity in vaccine clinical trials. Methods A review of the literature was conducted using PubMed as the primary database, with MeSH terms “leishmanin skin test” OR “Montenegro test” OR “Montenegro skin test.” Articles written in English that describe the history or standardization of leishmanin, the use of leishmanin in an IGRA, or the use of the LST in epidemiological studies or vaccine trials were prioritized in our appraisal of the literature.

Prevalence of Leishmania infection in three communities of Oti Region, Ghana

Background Leishmaniasis is a neglected tropical disease caused by parasites of the genus Leishmania and is transmitted by various species of female phlebotomine sand flies. The first report of cutaneous leishmaniasis (CL) in Ghana refer to a cluster of cases in 1999–2003 in the Ho municipality of the Volta Region. We conducted an epidemiological assessment in the Oti Region, encouraged by recent reports of potential cases of CL. Methodology/Principal findings Using a cross-sectional study design, the exposure to Leishmania was investigated in three communities of the Oti Region based on the leishmanin skin test (LST). LST results for 3,071 participants comprising 1091, 848, and 1132 persons from the communities of Ashiabre, Keri, and Sibi Hilltop, indicated an overall prevalence of exposure to Leishmania infection of 41.8% and individual community prevalence of 39.4%, 55.1%, and 34.2% respectively. Being male [AOR = 1.27; CI: 1.09, 1.49], and living in Keri [AOR = 1.83; CI: 1.43, 2.34] were associated with an increase in the odds of exposure to Leishmania. Being 5–10 years old [AOR = 1.48; CI: 1.06, 2.05], 11–17 years old [AOR = 2.03; CI: 1.45, 2.85], 18–40 years old [AORR = 2.83; CI: 1.81, 4.43] and 41–65 years old [AOR = 5.08; CI: 2.98, 8.68] were also significantly associated with increased odds of being exposed to Leishmania. Conclusions/Significance This study demonstrated exposure to Leishmania in the study communities and also identified associated factors. Future efforts aimed at reducing exposure to Leishmania infection in the study area should take the associated factors into consideration.

Revival of Leishmanization and Leishmanin

Leishmaniasis includes a spectrum of diseases ranging from debilitating cutaneous to fatal visceral infections. This disease is caused by the parasitic protozoa of the genus Leishmania that is transmitted by infected sandflies. Over 1 billion people are at risk of leishmaniasis with an annual incidence of over 2 million cases throughout tropical and subtropical regions in close to 100 countries. Leishmaniasis is the only human parasitic disease where vaccination has been successful through a procedure known as leishmanization that has been widely used for decades in the Middle East. Leishmanization involved intradermal inoculation of live Leishmania major parasites resulting in a skin lesion that following natural healing provided protective immunity to re-infection. Leishmanization is however no longer practiced due to safety and ethical concerns that the lesions at the site of inoculation that can last for months in some people. New genome editing technologies involving CRISPR has now made it possible to engineer safer attenuated strains of Leishmania, which induce protective immunity making way for a second generation leishmanization that can enter into human trials. A major consideration will be how the test the efficacy of a vaccine in the midst of the visceral leishmaniasis elimination program. One solution will be to use the leishmanin skin test (LST) that was also used for decades to determine exposure and immunity to Leishmania. The LST involves injection of antigen from Leishmania in the skin dermis resulting in a delayed type hypersensitivity (DTH) immune reaction associated with a Th1 immune response and protection against visceral leishmaniasis. Reintroduction of novel approaches for leishmanization and the leishmanin skin test can play a major role in eliminating leishmaniasis.

Toll-Like Receptors 2, 4, and 7, Interferon-Gamma, Interleukin 10, and Programmed Death Ligand 1 Transcripts in Leishmanin Skin Test-Positive Reactions of Ibizan Hound Dogs

The leishmanin skin test (LST) is an in vivo technique commonly used to evaluate the Leishmania-specific cellular immune response in dogs. However, information regarding the local immune response in LST-positive reactions is scarce. We examined the pattern of toll-like receptor 2 (TLR2), TLR4, TLR7, interleukin- (IL-) 10, interferon gamma (IFN-γ), and (program death ligand) PD-L1 gene expression in LST-positive reactions and paired normal-looking skin of nine infected Ibizan hound dogs. Healthy skin from ten seronegative dogs from a nonendemic area was analysed as a negative control. Immune gene expressions were examined by quantitative PCR (qPCR) analysis. LST-positive reactions presented significant upregulation of TLR2, TLR4, IL-10, IFN-γ, and PD-L1 and downregulation of TLR7 when compared with healthy skin of seronegative control dogs from a nonendemic area. All transcripts but TLR7 were significantly higher in LST-positive reaction than in paired normal-looking skin of Ibizan hound. The expression profile of immune genes in LST-positive reactions was similar to that previously observed in clinically lesioned skin of mildly diseased dogs with papular dermatitis due to Leishmania infantum infection. This data provide additional support for the important role of TLRs in canine leishmaniosis.

Surveillance for Leishmania asymptomatic infection in endemic foci of cutaneous leishmaniasis in Venezuela: a combination of leishmanin skin test and PCR using blood clots improves detection and enables identification of species

Background Little is known about the prevalence of asymptomatic leishmaniasis in Venezuela. The objective of this study was to quantify Leishmania asymptomatic infection in six endemic foci of cutaneous leishmaniasis (CL) in Portuguesa State, Venezuela, where no previous data were available. Methods Study of the prevalence of Leishmania asymptomatic infection was carried out in 841 individuals from six endemic foci of CL in the municipalities Sucre and Ospino, Portuguesa State. We applied the leishmanin skin test (LST) and the internal transcribed spacer 1 (ITS1) PCR to DNA from sera and blood clots of all LST-positive and 20% of LST-negative patients. Results Of 841 inhabitants tested by LST, 197 returned a positive reaction (23.42%); all of the LST-positives (197) and 121 negatives were screened by nested PCR using serum and blood clots. Among the LST-positive group, 2.54% were PCR-positive with sera, while 44.67% were positive with blood clots. In the LST-negative group, PCR was positive in 2.48% of serum samples and in 38.84% of blood clots. Conclusions It is recommended that LST and PCR on blood clots are used together to detect exposure and asymptomatic infection and for identification of the Leishmania species.

Leishmaniasis Caused by Leishmania major on the Glans Pe-nis: A Case Report

Cutaneous leishmaniasis (CL) is one of the prevalent parasitic diseases in Iran principally caused by two species, Leishmania major and L. tropica. Here, we present a rare case of a congenital form of CL around the glans penis from the central part of Iran in 2017. A 24-yr-old male patient from the central part of Iran presented with biennial ulceration of the glans penis. Diagnostic methods included physical and preclinical examination, microscopic observation, leishmanin skin test (LST), and serological tests including direct agglutination test (DAT). Nested PCR and sequencing analysis were used on the positive smears for confirmation of CL and Leishmania species identification. The preclinical results were normal, and no anti-Leishmania antibodies were detected in the peripheral blood of the patient using DAT. In abdominal ultrasonography, the spleen and liver size were normal. LST was positive (≥5 mm) after 72 h, and a few amastigote forms of Leishmania sp. were demonstrated under light microscopy. L. major was confirmed using nested PCR and sequencing analysis. The patient responded to oral administration of miltefosine (2.5 mg/kg/d) for 28 days. To the best of our knowledge, genital CL due to L. major has not been previously reported from Iran.

Prevalence of Cutaneous Leishmaniasis in Western Highlands in Yemen

Leishmaniasis in Yemen is still not fully investigated nor well studied. Recently, outbreaks of cutaneous leishmaniasis (CL) in western highland were declared. However, there are no reports concerning the disease and the circulating species in the region. The aim of this study was to determine the prevalence of cutaneous leishmaniasis in Utmah district located in Western Highlands in Yemen. A cross-sectional survey was carried out at those highlands. For the survey, 1165 participants were subjected to Leishmanin Skin Test (LST) accompanied with direct interviews and physical examination. The overall prevalence of cutaneous leishmaniasis in the district was 18.5% and the cutaneous leishmaniasis (CL) was more frequent in the escarpments with a prevalence of 37%, including 5.5% for active lesion and 31.5% for scar of healed lesions. Children under the age of 16 years old comprised most of the CL cases (76.3%). The escarpments of western highlands in Yemen were hyperendemic areas for CL and the infection was more prevalent in children.