Treat whole household to block trachoma transmission, researchers recommend
The spread of the eye infection trachoma could be effectively blocked if all members of an infected individual's household were treated for the disease, a UK-US study suggests. Trachoma occurs when the eye is infected with Chlamydia trachomatis bacteria and it is the leading cause of infectious blindness worldwide. It is spread by contact with eye discharge from an infected person, for example via towels, clothing and handkerchiefs or through flies that buzz around the face. The infection can be treated with antibiotics, and one of the main strategies for eliminating the disease entails the mass administration of drugs to large proportions of communities. One positive side effect of this approach is that it may also clear up other bacterial infections. However, treating whole communities with antibiotics is rather expensive, and results in many people receiving treatment who do not need it. It could also promote antibiotic resistance. Given these issues, researchers and public health workers are keen to find more targeted ways of tackling the problem. Scientists have known for many years that trachoma cases tend to cluster within households, but until now no-one has compared within - and between - household transmission rates. In this latest study, the scientists analysed the rates of transmission in four populations in Africa where trachoma infection is common. They compared rates of transmission within households to transmission rates between households. Their findings, published in the journal PLoS (Public Library of Science) Neglected Tropical Diseases, reveal that the disease spreads far faster within households than between households. Furthermore, infected people living in larger households contributed more to the number of new infections in the community than those living with fewer people. 'We have shown that within-household transmission is far more efficient, and accounts for almost three quarters of new infections across the four communities we studied,' commented David Mabey of the London School of Hygiene and Tropical Medicine in the UK. 'Failure to treat all infected members of a household during the mass administration of antibiotics is likely to lead to the rapid re-infection of that household, followed by a more gradual spread across the community. It is important to achieve high treatment coverage of infected households in mass treatment campaigns.' 'Trachoma can be a very debilitating disease - it is difficult for people in the developing world to work and get on with their everyday lives if they lose their sight,' added the lead author of the paper, Isobel Blake of Imperial College London, UK. 'Our research shows that the bacterial infection which causes trachoma can spread really easily within a household. If control programmes make sure they treat everyone who is living with an infected person, they can greatly reduce the spread of the infection.' According to the researchers, further work is now needed to identify the most affected household-based approaches to treatment. The symptoms of trachoma are extremely unpleasant. In the worst cases the insides of the eyelid may become so scarred that the eyelid turns in on itself, causing the eyelashes to rub against the eyeball, damaging the eye in the process and eventually leading to blindness if left untreated. Some 8 million people around the world are visually impaired as a result of trachoma infection and a further 46 million are in need of treatment. The WHO (World Health Organization) has set itself the goal of eliminating trachoma by 2020.
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United Kingdom, United States