The leprosy bacteria attack the skin and peripheral nerves first of all. The first symptoms, which can be seen during the outbreak of the disease are mostly patches on the skin. These appear lighter or darker than the surrounding skin, depending upon the skin colour of the patient.
Numb Skin Patches
Characteristic for leprosy is the lack of feeling in these skin patches. This loss of feeling is due to damage of the peripheral nerves. Additionally, there is further deterioration of nerves of the sensory and also of the motor nervous system. This leads to the typical paraesthesia and also to crippling (most frequently in hands and feet, but also in the area of facial nerves).
Loss of Sense of Touch and Pain
Without treatment, the infection spreads further in the skin and the nervous system. There are extensive skin changes, crippling and complete loss of sense of touch and pain in the hands and feet. Because of inadequate shutting of the eyelids and lack of feeling in the conjunctiva of the eyes, a scarring blindness of the eyes develops.
Injuries and Loss of Limbs
Injuries to the hands and feet, if left unattended, develop into extensive secondary infections, which also attack the bones. This leads increasingly to loss of limbs and entire body parts. This development can be arrested or prevented through good care and precaution. The dreadful vision of the crippled, blind leper is a result of lack of medical guidance and lack of self-help opportunities for the victims – mostly due to poverty and social exclusion.
The diagnosis of leprosy is based on the typical finding of loss of sensation, weakness of the muscles and swollen peripheral nerves. Special adjuvants are not required. For the confirmation of the diagnosis and the classification of the stages, skin smears are helpful. The leprosy bacillae can thus be analysed under the microscope.
Since 1981, multi-drug therapy (MDT) is used for the treatment of leprosy on the recommendation of World Health Organisation (WHO). MDT consists of the three agents dapson, rifampicin und clofazimin. MDT is extremely safe, efficient and inexpensive. A drug resistance to all the three drugs has not yet been observed.
Breaking the Chain of Infection
The aim of the treatment is the complete elimination of the bacteria. In the majority of the cases, this is achieved through the ingestion of MDT in the course of six months for patients with low bacteria infestation (PB patients) and after a 12-month MDT treatment for patients with high bacteria infestation (MB patients). Relapses after completed treatment do occur, but only to the extent of less than 1%. The question as to whether relapses can be prevented through a longer period of treatment, is a controversial discussion to this date. There are, however, indications that the length of the treatment plays a role in the frequency of relapses in the case of high bacterial infestation. MDT weakens the bacteria as early as within a very short active period, so that the patients are no longer infectious. This disrupts the chain of infection.
Today, it is believed that leprosy, same as influenza, is transmitted via droplets with bacterial content expelled from the mouth and the nasal mucous membrane during coughing or sneezing. There are, however, indications that the bacterium can also be transmitted from skin to skin in the case of high infestation.
To date, it has not been possible to culture the mycobacterium leprae in test tubes. This makes difficult the research on reproduction cycles, metabolism and transmission methods of the virus as well as the development of an effective vaccine. Anyhow, for research purposes, the leprosy bacteria can be cultured in experiments on animals, particularly on the soles of the feet of mice. Meanwhile, the complete analysis of the genetic structure has taken place. It shows that mycobacterium leprae is a very old virus historically, which has very little inclination towards genetic mutations. The strength of the bacteria lies not in its ability to adjust and develop resistance, but in its ability to linger unnoticed in the human being and to produce little noticeable symptoms even during affliction, so that many people are infected before it is diagnosed and treated.
Not every person exposed to the leprosy bacteria suffers from the disease. Evidently, the immune system is mostly in a position to make the intrusive leprosy bacteria harmless. It is known that the vaccination against tuberculosis (mycobacterium tuberculosis) can also have a certain protective effect against mycobacterium leprae.
The question that remains unexplained even today is why individual patients suffer from inflammatory episodes (so-called reactions) in the course of the medicinal treatment, while others are spared these attacks. Even in these inflammatory reactions, immunological processes are at work. Such acute episodes often lead to devastating nerve damage and thereby to secondary crippling and disablement.