Leprosy

What is leprosy?

Leprosy is a disease caused by the bacteria Mycobacterium leprae that causes damage to the skin and the peripheral nervous system. The disease develops slowly (from six months to 40 years!) and results in skin lesions and deformities, most often affecting the cooler places on the body (for example, eyes, nose, earlobes, hands, feet, and testicles). The skin lesions and deformities can be very disfiguring and are the reason that infected individuals were considered outcasts in many cultures. Although human-to-human transmission is the primary source of infection, three other species can carry and (rarely) transfer M. leprae to humans; chimpanzees, mangabey monkeys, and nine-banded armadillos. The disease is termed a chronic granulomatous disease because it produces inflammatory nodules (granulomas) in the skin and nerves over time.

Child with leprosy

Causes

1. Mycobacterium leprae and Mycobacterium lepromatosis are the causative agents of leprosy.

2. Genetics

Several genes have been associated with a susceptibility to leprosy.

Name	Locus	OMIM	Gene
LPRS1	10p13	609888
LPRS2	6q25	607572	PARK2, PACRG
LPRS3	4q32	246300	TLR2
LPRS4	6p21.3	610988	LTA

Signs and Symptoms and

Unfortunately, the early signs and symptoms of leprosy are very subtle and occur slowly (usually over years). Numbness and loss of temperature sensation (cannot sense very hot or cold temperatures) are some of the first symptoms that patients experience. As the disease progresses, the sensation of touch, then pain, and eventually deep pressure are decreased or lost. Signs that occur, such as relatively painless ulcers, skin lesions of hypopigmented macules (flat, pale areas of skin), and eye damage (dryness, reduced blinking) are experienced before the large ulcerations, loss of digits, and facial disfigurement develop. This long-time developing sequence of events begins and continues on the cooler areas of the body (for example, hands, feet, face, and knees)

Transmission

Researchers suggest that M. leprae are spread person to person by nasal secretions or droplets. They speculate that infected droplets reach other peoples' nasal passages and begin the infection there. Some investigators suggest the infected droplets can infect others by entering breaks in the skin. M. leprae apparently cannot infect intact skin. Rarely, humans get leprosy from the few animal species mentioned above. Routes of transmission are still being researched for leprosy.

Since the disease often appeared in family members, some people thought it was hereditary; other people noted that if there was little or no contact with infected individuals, the disease did not infect others. Consequently, some cultures considered infected people (and occasionally their close relatives) as "unclean" or as " lepers" and ruled they could not associate with uninfected people. Often infected people had to wear special clothing and ring bells so uninfected people could avoid them.

Diagnosis

The majority of cases of leprosy are diagnosed by clinical findings, especially since most current cases are diagnosed in areas that have limited or no laboratory equipment available. Hypopigmented patches of skin or reddish skin patches with loss of sensation, thickened peripheral nerves, or both clinical findings together often comprise the clinical diagnosis. Skin smears or biopsy material that show acid-fast bacilli with the Ziel-Nelson stain or the Fite stain (biopsy) can diagnose multibacillary leprosy, or if bacteria are absent, diagnose paucibacillary leprosy. Other tests can be done, but most of these are done by specialized labs and may help a clinician to place the patient in the more detailed Ridley-Jopling classification and are not routinely done (lepromin test, phenolic glycolipid-1 test, PCR, lymphocyte migration inhibition test or LMIT). Other tests such as CBC test, liver function tests, creatinine test, or a nerve biopsy may be done to help determine if other organ systems have been affected.

Treatment

The majority of cases (mainly clinically diagnosed) are treated with antibiotics. The recommended antibiotics, their dosages and length of time of administration are based on the form or classification of the disease and whether or not the patient is supervised by a medical professional. In general, paucibacillary leprosy is treated with two antibiotics, dapsone and rifampicin, while multibacillary leprosy is treated with the same two plus a third antibiotic, clofazimine. Usually, the antibiotics are given for at least six to 12 months or more. Each patient, depending on the above criteria, has a schedule for their individual treatment, so treatment schedules should be planned by a clinician knowledgeable about that patient's initial diagnostic classification.

Antibiotics can treat paucibacillary leprosy with little or no residual effects on the patient. Multibacillary leprosy can be kept from advancing, and living M. leprae can be essentially eliminated from the person by antibiotics, but the damage done before antibiotics are administered is usually not reversible. Recently, the WHO suggested that single-dose treatment of patients with only one skin lesion with rifampicin, minocycline (Minocin), or ofloxacin (Floxin) is effective. Studies of other antibiotics are ongoing.

The role for surgery in the treatment of leprosy occurs after medical treatment (antibiotics) has been completed with negative skin smears (no detectable acid-fast bacilli) and is often only needed in advanced cases. Surgery is individualized for each patient with the goal to attempt cosmetic improvements and, if possible, to restore limb function and some neural functions that were lost to the disease.

Prevention

In a recent trial, a single dose of rifampicin reduced the rate at which contacts acquired leprosy in the two years after contact by 57%; 265 treatments with rifampicin prevented one case of leprosy in this period. A non-randomized study found that rifampicin reduced the number of new cases of leprosy by 75% after three years.

BCG offers a variable amount of protection against leprosy as well as against tuberculosis.

Posted in: Leprosy