A Contact Cohorts Analysis (COCOA) study, conducted in four districts of northwestern Bangladesh, found that leprosy can transmit from an infected person to another who shares the same home albeit to a lesser extent.
The new findings during the ongoing Covid-19 pandemic will help global health experts in fighting to eliminate the disease by coming up with new action plans.
“People who share a home with a person affected by leprosy do have only a low risk of contracting the disease,” said the report that appeared in The Leprosy Mission International (TLMI) website recently.
Dr Cynthia Ruth Butlin of The Leprosy Mission England and Wales led the six-member research team that went through leprosy-related information of over 20 years in Bangladesh.
The report revealed that members who share the same home are at higher risk of infection than other members of their community.
TLMI said that this new research will change the way it has been tracing new cases and remained active globally to end the spread of the disease by 2035. However, TLMI said that there is not a high chance of catching leprosy, even if it is present in your home.
“Less than two percent of people who lived with a person affected by leprosy will contract this disease,” the study revealed.
TLMI expert team went through a close analysis of households of historic cases of leprosy in the Northwestern part of the country.
They analysed the new cases diagnosed within the households where already an infected person existed.
The research indicates that “it’s less than two percent of household members, which is a reminder that there is no need to isolate people affected by leprosy”.
How will the new findings help TLMI?
The new findings of the study are a valuable tool in fighting to end the leprosy transmission globally.
The study provides new information to the global health experts that a rate of four among 1,000 household contacts see Paucibacillary leprosy (PB) transmission at home per year.
On the other hand, the new findings from the COCOA study showed that there is a higher rate of transmission of Multibacillary leprosy (MB) at home.
However, the MB leprosy transmission rate rises to around 13 among 1,000 households per year which is higher than the PB leprosy transmission rate.
Earlier, this study was conducted, leprosy caseworkers would visit as many leprosy-affected homes as possible to check the household members for signs of leprosy, but they were often not clear on which homes to prioritise.
Although priority has always been placed on MB patients, the new findings confirm that the household contacts must be prioritised in contact tracing activities.
TLMI study now suggests that global health experts must prioritise homes with MB leprosy cases, especially in the first year after the initial diagnosis, when new case detection within the household is at its highest rate.
Priority in Bangladesh
As the study provides new knowledge about the disease, TLMI is going to change its course of leprosy disease-related activities in Bangladesh.
The practices in the country have already begun to change as MB houses receive regular follow up calls from the caseworkers.
The regular follow up calls mean that TLMI Bangladesh can diagnose and treat leprosy infected people at an earlier stage than before, which reduces the chances of transmission within a household or community.
As before, all households with leprosy cases were taught about how to identify the early signs of leprosy, which include patches of skin that are differently coloured and often have no feeling.
The leprosy Mission International now hopes to be more specific in conducting its activities while fighting against the disease across the world.
The report said that TLMI will use another excellent tool to slow down the leprosy transmission rate and will be able to eliminate the disease by 2035.
Research area and respondents in Bangladesh
The research was conducted using routinely collected data (from the period of planned surveillance of contacts in index household drawn from 20 annual cohorts of new case diagnoses) in four districts of north-west Bangladesh.
The Rural Health Programme (RHP), under The Leprosy Mission International, Bangladesh (TLMIB), supports the national leprosy control programme.
The four districts have over seven million people. The household contact examinations 291 majorities of the population is employed in manual work and lives near or below the poverty line.
According to national leprosy control reports, the region has high leprosy prevalence as it had 4.57/10,000 leprosy cases in 1995 and in 2017 it was 0.74/10,000.
However the most individuals resident in this area who were treated for leprosy over the past 30 years are known to the programme.
Altogether 9,538 index cases were enrolled in the study in four districts in the last 21 years, which was 52.37 percent of all new cases diagnosed in the targeted years and 62.59 percent of all cases who met inclusion criteria.
Who conducted the study?
Dr Cynthia Ruth Butlin of The Leprosy Mission England and Wales, Peterborough led the six-member research team.
The five other members are- Bob Bowers of Menzies Health Institute Queensland; Peter Nicholls an independent statistician, Emily Quilter of London School of Hygiene and Tropical Medicine, Khorshed Alam and Suren Singh of TLMI, Dhaka Bangladesh.
The research paper titled “Household contact examinations: outcome of routine surveillance of cohorts in Bangladesh” was accepted for publication on June 25 last year.
(The research report can be downloaded here- Household contact examinations: outcome of routine surveillance of cohorts in Bangladesh )
What is leprosy?
According to the World Health Organization (WHO), Leprosy, also known as Hansen’s disease, is a chronic infectious disease caused by Mycobacterium leprae (a relative of TB).
This disease primarily affects the skin, the peripheral nerves, mucosal surfaces of the upper respiratory tract and the eyes. The first signs of leprosy are patches of skin which look paler than normal or sometimes nodules on the skin.
It is known to occur at all ages ranging from early infancy to very old age.
WHO as well as organisations like TLMI provide confirmation that leprosy is curable and treatment in the early stages can prevent disability.
Leprosy is likely transmitted via droplets, from the nose and mouth, during close and frequent contact with untreated cases, according to the WHO.
The people with weak immune systems thanks to poor nutrition are less able to fight the disease.
If leprosy is not treated it attacks the nerves that supply feeling to the hands, feet, eyes and parts of the face.
Despite efforts of governments and non-governmental organisations in endemic countries, leprosy remains to be one of the neglected tropical diseases which is yet fully controlled.
What stops leprosy infections?
TLMI report shows that “A leprosy infected person, undergoing Multi Drug Therapy (MDT) treatment will stop being infectious within 72 hours of starting treatment and, even before treatment, only a minority of those affected by leprosy are infectious.”
According to the existing information about the disease, 95 percent of the world population is naturally immune to the disease.
TLMI report said that the latest findings will work as further evidence that leprosy is a mildly infectious and of course a curable disease.
After finding new information about the transmission of leprosy, the health experts suggested educating people about the early signs and symptoms of leprosy and to attempt to reduce any misconceptions or undue fear about the diagnosis.
They recommended annual re-examinations, and prioritise MB index households before PB index households in order to detect the highest number of new cases.
Examination of one household where there is an MB index case is more likely to produce new cases at any time point in the routine surveillance period.
When first seen, people contracted the disease should be warned about their continuing risk of developing leprosy.