What is the test for leprosy? How is it performed? What are the types of specimens used for diagnosis? Get detailed answers to these and other questions about laboratory diagnostics for Hansen’s disease (leprosy).

Diagnosing Leprosy: Clinical Presentation and Confirmatory Tests

Hansen’s disease, or leprosy, is primarily diagnosed based on the patient’s clinical presentation. However, to confirm the diagnosis and classify the disease, additional laboratory tests are crucial. The diagnosis is typically confirmed through skin or nerve biopsy and acid-fast staining.

Role of the National Hansen’s Disease Program

In the United States, the National Hansen’s Disease Program provides diagnostic services for leprosy. This specialized program plays a vital role in ensuring accurate diagnosis and appropriate management of the disease.

Limitations of Serological Tests for Leprosy

While some serological tests have been developed to detect leprosy, they lack sufficient sensitivity and specificity to be used as reliable diagnostic tools. For this reason, these serological tests are not recommended for the diagnosis of Hansen’s disease.

Types of Specimens for Leprosy Diagnosis

Depending on the suspected form of leprosy, healthcare providers may collect the following specimens for diagnosis:

• Skin smears from the earlobes, elbows, and knees
• Skin biopsy from the edges of active skin patches
• Nerve biopsy from thickened nerves
• Skin and nerve biopsies

Histopathological Changes in Leprosy

In the multibacillary form of leprosy, tissue biopsy may reveal characteristic histopathological changes, including the presence of large numbers of “foam cells.” These foam cells are macrophages that have ingested, but are unable to digest, the Mycobacterium leprae bacteria, which then multiply and spread throughout the body.

Acid-Fast Staining for Leprosy Diagnosis

Acid-fast staining, using the Ziehl-Neelsen method with 5% sulphuric acid as the decolorizing agent, is a key diagnostic tool for leprosy. The presence of acid-fast bacilli in the sample confirms the diagnosis of Hansen’s disease.

Photomicrographic Evidence of Leprosy

The photomicrographs included in the article provide visual evidence of the histopathological changes associated with leprosy. These images show the presence of granulomas, nerve infiltration, and the characteristic “foam cells” found in the multibacillary form of the disease.

How do serological tests for leprosy differ from the Ziehl-Neelsen acid-fast staining method? Serological tests, while developed by some researchers, lack the sensitivity and specificity to be used as reliable diagnostic tools for leprosy. In contrast, the Ziehl-Neelsen acid-fast staining method is a well-established and highly specific technique for confirming the presence of Mycobacterium leprae, the causative agent of Hansen’s disease.

What is the role of the National Hansen’s Disease Program in the United States? The National Hansen’s Disease Program is a specialized program that provides diagnostic services for leprosy in the United States. This program plays a critical role in ensuring accurate diagnosis and appropriate management of the disease, which is essential for effective treatment and control of Hansen’s disease.

What types of specimens are collected for leprosy diagnosis? Depending on the suspected form of leprosy, healthcare providers may collect skin smears from the earlobes, elbows, and knees, skin biopsies from the edges of active skin patches, nerve biopsies from thickened nerves, or a combination of skin and nerve biopsies. These specimens are then analyzed to confirm the diagnosis and classify the disease.

How do the histopathological changes in multibacillary leprosy differ from the paucibacillary form? In the multibacillary form of leprosy, tissue biopsies may reveal the presence of large numbers of “foam cells” – macrophages that have ingested but are unable to digest the Mycobacterium leprae bacteria. These foam cells then serve as a method of transport for the bacteria, leading to the development of multiple lesions throughout the body. In contrast, the histopathological changes in the paucibacillary form may not be as pronounced or widespread.

What is the significance of acid-fast staining in the diagnosis of leprosy? The Ziehl-Neelsen acid-fast staining method is a crucial diagnostic tool for leprosy. The presence of acid-fast bacilli in the sample confirms the diagnosis of Hansen’s disease, as it indicates the presence of Mycobacterium leprae, the causative agent of the disease.

How do the photomicrographs in the article provide evidence of the histopathological changes in leprosy? The photomicrographs included in the article demonstrate the characteristic histopathological changes associated with leprosy, such as the presence of granulomas, nerve infiltration, and the accumulation of “foam cells” in the multibacillary form of the disease. These visual representations help to further understanding of the pathological processes underlying Hansen’s disease.

Laboratory Diagnostics | Hansen’s Disease (Leprosy)

Hansen’s disease is diagnosed based on clinical presentation and the diagnosis is confirmed by skin or nerve biopsy and acid fast staining. In the United States, the National Hansen’s Disease ProgramExternal provides diagnostic services.

Some serological tests have been developed and promoted by some investigators, but they lack sufficient sensitivity and specificity to be used as diagnostic tests. For this reason they are not used to diagnose Hansen’s disease.

Specimens and Tests

Depending on the form of leprosy suspected by the treating physician, the following specimens may be collected:

• Skin smears from the earlobes, elbows, and knees
• Skin biopsy from edges of active patches
• Nerve biopsy from thickened nerves

Skin and nerve biopsy

Biopsies are needed to definitively confirm a diagnosis of Hansen’s disease and to classify the disease, and slit skin smear may also be helpful in diagnosing those with mutlibacillary disease.

In the multibacillary form of Hansen’s disease, tissue biopsy of various affected sites may reveal typical histopathologic changes that show large numbers of foam cells. Foam cells are macrophages that have ingested, or phagocytized, M. leprae bacteria, but are unable to digest the organisms, who in turn multiply and use the macrophage as a method of transport throughout the body. This is how the bacteria cause the multiple lesions that may appear in all parts of the body in MB leprosy patients.

This photomicrograph reveals some of the classic histopathologic changes found in a skin section from an individual with a case of the leprosy, which may have been the paucibacillary form of the disease, though this has not been confirmed. Shown here is a nerve surrounded by a dense infiltrate consisting of undifferentiated histiocytes and large numbers of lymphocytes. The nerve sheath and endoneural region of the nerve were also infiltrated. This neural involvement was found to be independent of any pathology of the upper corium.

This photomicrograph reveals some of the histopathologic changes in a specimen of human testicular tissue, which included a large number of “foam cells”. These changes were attributed to a case of multibacillary (MB) leprosy.

Acid fast staining

The Ziehl-Neelson method using 5% sulphuric acid as decolorizing agent is used. The presence of acid-fast bacilli confirms the diagnosis of Hansen’s disease.

This acid-fast-stained photomicrograph of a tissue sample extracted from a patient with leprosy shows a chronic inflammatory lesion known as a granuloma, within which numerous red-colored M. leprae bacteria are visible.

This photomicrograph of a skin tissue sample from a patient with leprosy shows a cutaneous nerve, which had been invaded by numerous M. leprae bacteria (shown in red).

Page last reviewed: February 10, 2017

Content
source: Centers for Disease Control and Prevention
, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID)
, Division of High-Consequence Pathogens and Pathology (DHCPP)

United States National Hansen’s Disease ProgramExternal
file_external

World Health OrganizationExternal
file_external

Lepromin skin test Information | Mount Sinai

Leprosy skin test; Hansen disease – skin test

The lepromin skin test is used to determine what type of leprosy a person has.

Leprosy is caused by the organism Mycobacterium leprae. The leprosy test involves injection of an antigen just under the skin to determine if your body has a current or recent leprosy infection. The injection site is labeled and examined 3 days and 28 days later to see if there is a reaction.

How the Test is Performed

A sample of inactive (cannot cause infection) leprosy-causing bacteria is injected just under the skin, often on the forearm, so that a small lump pushes the skin up. The lump indicates that the antigen has been injected at the correct depth.

The injection site is labeled and examined 3 days, and again 28 days later to see if there is a reaction.

How to Prepare for the Test

People with dermatitis or other skin irritations should have the test performed on an unaffected part of the body.

If your child is to have this test performed, it may be helpful to explain how the test will feel, and even demonstrate on a doll. Explain the reason for the test. Knowing the “how and why” may reduce the anxiety your child feels.

How the Test will Feel

When the antigen is injected, there may be a slight stinging or burning. There may also be mild itching at the site of injection afterward.

Why the Test is Performed

Leprosy is a long-term (chronic) and potentially disfiguring infection if left untreated. It is caused by Mycobacterium leprae bacteria.

This test is a research tool that helps classify the different types of leprosy. It is not recommended as the main method to diagnose leprosy.

Normal Results

People who don’t have leprosy will have little or no skin reaction to the antigen.  People with a particular type of leprosy, called lepromatous leprosy, will also have no skin reaction to the antigen.

What Abnormal Results Mean

A positive skin reaction may be seen in people with specific forms of leprosy, such as tuberculoid and borderline tuberculoid leprosy. People with lepromatous leprosy will not have a positive skin reaction.

Risks

There is a very small risk for an allergic reaction, which may include itching and rarely, hives.

Dupnik K. Leprosy (Mycobacterium leprae). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 250.

James WD, Elston DM, Treat JR, Rosenbach MA, Neuhaus IM. Hansen disease. In: James WD, Elston DM, Treat JR, Rosenbach MA, Neuhaus IM, eds. Andrews’ Diseases of the Skin. 13th ed. Philadelphia, PA: Elsevier; 2020:chap 17.

Last reviewed on: 9/1/2021

Reviewed by: Jatin M. Vyas, MD, PhD, Associate Professor in Medicine, Harvard Medical School; Associate in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A. D.A.M. Editorial team.

ELISA test strips detect leprosy immune response – immunology

Packard FluoroCount microplate reader adapted to test strip readability (photo courtesy of PerkinElmer).

ESEQuant ELISA test strip reader (photo courtesy of Qiagen).

Tests for detecting asymptomatic Mycobacterium leprae infection or predicting progression to leprosy with field use are urgently needed to determine both cellular and humoral immunity.

Leprosy, a curable infectious disease caused by Mycobacterium leprosy ( M. leprae ) that affects the skin and peripheral nerves, is one of six diseases considered a major threat in developing countries because continuous transmission in endemic areas can occur from large numbers of asymptomatically infected individuals.

Infectious disease specialists from the Leiden University Medical Center (Netherlands) with colleagues in Ethiopia recruited to investigate the negative diagnosis of human immunodeficiency virus (HIV) have identified untreated leprosy patients for the first time, as well as healthy endemic patients in the control group since October 2011 until November 2012. Leprosy was diagnosed on the basis of clinical, bacteriological and histological observations and classified by skin biopsy.

Combined diagnostic value of interferon-gamma-induced protein-10 (IP-10), interleukin-10 (IL-10), and antiphenolic glycolipid-I (PGL-I) antibodies was tested using M. leprae stimulated blood from patients with leprosy and endemic control group. To reduce the overall test time, the minimum time for a complete blood count required to detect distinctive responses was investigated. To accommodate Lateral Flow Assays (LFA) enzyme immunoassays in the field, dry format LFAs for IP-10 and anti-PGL-I antibodies have been developed that can be stored and transported at ambient temperature. In addition, the multiplex LFA format was used to simultaneously detect anti-PGL-I and IP-10 antibodies. To improve the sensitivity and accuracy of the quantification, upconverting phosphor (UCP) crystal pointing technology was applied to all LFAs.

After immunochromatography, test strips are scanned using a Packard FluoroCount microplate reader (PerkinElmer; Waltham, MA, USA) equipped with an infrared (IR) laser. Upon IR excitation at 980 nm, the phosphorus particles emit green light, which is detected by a 550 nm bandpass filter. For strip analysis in Ethiopia, a lightweight portable test strip reader with UCP capability (UCP-Quant – ESEQuant reader equipped with IR diode; QIAGEN Lake Constance GmbH; Stockach, Germany) was used.

Single and multiplex UCP-LFA correlate well with enzyme immunoassay (ELISA) running in parallel. Assay performance based on dry reagents and portable, lightweight UCP-LFA readers have shown excellent stability in the field. Notably, the detection of IP-10 levels in stimulated samples reduced the time for a complete blood count from 24 hours to 6 hours. In addition, unstimulated plasma IP-10/IL-10 ratios differed significantly between patients and endemic controls, indicating the ability to detect infection M. leprae in endemic areas.

The authors concluded that dry-format UCP-LFAs are low-tech, reliable assays for detecting relevant cytokine and antibody responses to M. leprae in the field. The high levels of IP-10 and the shorter required CBC time demonstrate the benefit of this cytokine in distinguishing leprosy patients from endemic controls. The study was published May 8, 2014 in The Public Library of Scientific Neglected Tropical Diseases ( Public Library of Science Neglected Tropical Diseases ).

Related Links:
Leiden University Medical Center
PerkinElmer
QIAGEN Lake Constance GmbH

Visit expo >

COVID-19 Antigen Self-Test

Panbio COVID-19 Antigen Self-Test

New

Troponin I, NT-proBNP & CK-MB Combo Test

Absoludy Cardiac Triple

New

Laboratory Software

Atellica Connectivity Manager

Leprosy: symptoms, treatment, prevention

One of the oldest diseases known to medicine, leprosy (another name – leprosy) for many centuries was considered incurable. Currently, this infectious disease with a chronic course, which is one of the types of granulomatosis, is quite treatable. The disease is systemic in nature, affecting mainly the skin, peripheral nervous system, organs of vision and some internal organs.

General

The acid-fast bacterium Mycobacterium leprae is the causative agent of leprosy, and its characteristics are now well known to bacteriologists and infectious disease specialists. The disease is most common in countries with a hot climate. Currently, there are about 12 million patients in the world, the bulk of which are residents of developing countries. Every year, doctors identify approximately 500-800 thousand new infected, and men get sick about twice as often as women.

The stick has a low contagiousness: from a sick person to a healthy person, the disease is transmitted, as a rule, after prolonged direct contact or by airborne droplets. The patient excretes mycobacteria with physiological fluids and feces. Sources of infection are only infected people; cases of transmission of the disease in other ways have not been proven to date.

Signs of disease

Doctors distinguish four clinical varieties of leprosy, which differ in symptoms and the scope of damage to internal organs. The course of the disease in each of the cases goes through four stages: stationary, progressive, regressive, and at the end of the disease – residual. During the first two stages, the foci of the disease may worsen, despite the intensity of therapy.

Consider the symptoms of leprosy for each of the varieties.

• Lepromatous. This form of the disease is characterized by extensive lesions of the skin, mucous membranes, organs of vision, lymph nodes, peripheral nerve fibers and internal organs. Skin changes look like symmetrical red-brown spots on the face, arms, legs and back. At first, the skin in these places becomes smooth and shiny, but after a few years it thickens and becomes bumpy. A characteristic “lion’s mask” is formed on the face. The nasal passages are bent, the nose sags, the voice becomes hoarse and nasal. Vision deteriorates, if left untreated, complete blindness can occur. In the future, the bumpy surface of the skin begins to peel off and become covered with ulcers, loses sensitivity.
• Tuberculoid. In the initial phase of the disease, clearly defined spots with weak pigmentation appear on the skin. Spots are localized on the face, arms and torso. After a while, red-violet papules develop along the border of the spots, which later transform into annular plaques with a depigmented center. The skin of the affected areas becomes dry and keratinized. Due to damage to the nerve endings, the sensitivity of the skin is lost, then the patient may develop paresis or paralysis of the limbs, trophic ulcers and contractures appear on the feet, and muscle tissues atrophy. Internal organs are usually not affected.
• Undifferentiated. Subsequent transformation into a lepromatous or tuberculoid form is possible, therefore it is often considered as the initial stage of the disease, and not a separate variety. It manifests itself as rashes on the skin in the form of spots of different sizes and colors. The skin in these areas first acquires hypersensitivity, then almost completely loses sensitivity. Often, skin manifestations heal on their own, but the disease can become more severe.
• Border. It is characterized by diverse skin lesions, spots are combined with plaques and tuberosity, although sensitivity is reduced, it remains. There is no symmetry of skin manifestations. The nose and brow ridges increase, the earlobes become thinner.

Clinical examination

Leprosy is a disease with an extremely long incubation period, which lasts, on average, about 5 years, but there are cases when more than a decade has passed between infection and the appearance of external signs. The only way to diagnose is to identify the causative agent of leprosy in scrapings taken from the nasal mucosa, skin lesions and in the biomaterial of swollen lymph nodes. A bioassay can be carried out with the introduction of an isolated culture of mycobacteria to guinea pigs. The most accurate result is obtained by bacterioscopy and the study of histological preparations of the studied tissues. The lepromine test allows you to determine the type of leprosy, which gives a sharply positive result in the tuberculoid form of the disease and negative in the lepromatous form. Borderline forms give a weakly positive or negative answer.

Is recovery possible?

Modern medicine has an extensive arsenal of tools and techniques for the treatment of leprosy. In the presence of extensive skin lesions, a positive result of microscopic examination, or recurrence of the disease, hospitalization is necessary.

The course of treatment takes a long time and includes:

• taking anti-leprosy drugs of the sulfonic series, which are prescribed in courses and periodically replaced so as not to cause addiction;
• taking antibiotics, vitamins, adaptogens, immunocorrectors, hepatoprotectors and other drugs depending on the current state;
• BCG vaccination to improve immune reactivity;
• massage, exercise therapy, physiotherapy to avoid disability;
• psychotherapeutic treatment.

In addition, it may be necessary to correct the fundus, reconstruct tendons and nerve endings, surgical removal of contractures and other interventions. The patient needs to be observed on an outpatient basis for several years after discharge from the antileprosy hospital in order to prevent relapses.

Frequently asked questions from patients

How is leprosy transmitted in the family?

If there is a patient with leprosy in your family, the prevention of the disease for him and for other members of his family consists in carefully observing the usual rules of hygiene. The causative agent is not highly contagious, and the lack of close contact will allow loved ones to maintain health.

Is leprosy treated at home?

The need to isolate a patient with leprosy in a special medical institution depends on the form of the disease, on the degree of damage to the skin and internal organs. In the case of a mild course of the disease, therapy is carried out on an outpatient basis.