2023-06-23 05:30:00
People who live in the same household as a leprosy patient sooner or later often become ill themselves. A single dose of a highly effective drug can prevent this, as a study from China shows.
Often unnoticed for a long time, leprosy leads to the mutilation of the infected people.
Reuters Stringer / Reuters
Geruzinha, as the woman from São Raimundo Nonato in north-eastern Brazil is called, was hit by the news like a slap in the face. Exactly two years had passed since the doctor had confirmed that she was cured of leprosy.
For 12 months she had been taking a combination of three antibiotics every day. The skin changes typical of leprosy had slowly receded, and you could no longer tell that she was suffering from a particularly aggressive form of leprosy.
Then a routine check-up at the village health center suggested that her two daughters, aged 15 and 17, might have early-stage leprosy. A microscopic examination of skin samples in the hospital confirmed the diagnosis: the girls were with Mycobacterium leprosy the causative agent of leprosy.
Eight times the risk of infection
The woman’s painful experience in the Brazilian hinterland reflects a phenomenon that leprosy researchers have known for many years: Often, family members of leprosy patients also become victims of the disfiguring disease. They are eight times more likely to develop leprosy than people from households without a leprosy patient.
It usually takes four to five years for leprosy to become visible. Sometimes a lot more. Since people can already be contagious before they have any noticeable signs on their skin, the leprosy pathogens are usually passed on undetected.
They are transmitted via secretions from the nose and mouth, which spread over the face and uncovered areas of skin, for example during sleep. Since children and adults mostly sleep naked in tropical regions, the bacterium has a good chance of getting from a sick to a healthy person. If several people sleep in one bed or – as is common in rural Brazil – in a hammock, the risk of infection is particularly high.
The World Health Organization (WHO) has long advocated treating members of the household of a leprosy patient prophylactically with an antibiotic that is effective against the pathogen. Because of the poor health infrastructure in the regions where the leprosy patients live, only one-time treatment is possible.
Insufficient protection rate with the previous drug
In earlier studies, the drug rifampicin, which is effective in tuberculosis, was used for this purpose. Although tuberculosis and leprosy bacteria are closely related, studies with rifampicin have shown significantly variable effects. The protection rate for family members was never more than 30 percent over a four-year period.
It is assumed that the reason for the low protective effect of rifampicin is that a single dose is not sufficient to kill all the leprosy bacteria present. On the other hand, rifapentine, a further development of rifampicin, is extremely effective against various types of mycobacteria, including the leprosy pathogen, even at low concentrations. The drug also stays in the body much longer than rifampicin. It therefore seems to be more suitable for a one-off treatment of contact persons.
A group of Chinese scientists has now tested this hypothesis in a study. They report on this in the renowned New England Journal of Medicine. In a first step, the researchers identified villages in the south-west of the country in which leprosy had been regularly documented over the past ten years. They then selected households in those communities where one person had been diagnosed and treated for leprosy within the past three months.
They finally recruited 7,450 contact persons from the households, who they randomly divided into three groups: In the first group, the household members received the promising drug rifapentine as a single dose. The second group of contacts was treated with the standard therapy rifampicin for comparison purposes. In the third group, household members received a placebo. All contact persons were then regularly checked for leprosy, and neither the doctors nor the patients knew who had received which treatment.
The results of the study are striking: Within the study period of four years, a total of 24 new cases of leprosy occurred in family members, 18 of them in contact persons who had not been treated (placebo group) and 5 in persons who had received the previous « standard therapy» had received rifampicin. Only a single case was detected in the relatives treated with rifapentine.
From this, the scientists calculated that a systematic treatment of contact persons with the new drug at the population level could prevent 84 percent of all new leprosy diseases. If the prevention concept were consistently implemented in all countries where leprosy is still a feared tropical disease, the number of new cases would decrease continuously, the researchers write. This would sooner or later make the biblical scourge of mankind disappear.
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