It is difficult to comprehend modern life sans nighttime light. But the amenity comes at a price. Bruno A S De Medeiros and Alessandro Barghini at University of Sao Paulo in Brazil recently found that light pollution encourages the spread of infectious diseases. The biologist duo share their finding, published in Environmental Health Perspectives on August 1, in an email interview with Salonie Chawla
.jpg "Bruno A S De Medeiros and Alessandro Barghini")
How does artificial light affect insects?
The strong illumination of artificial light attracts insects.
We reviewed the epidemiological information on three insect-borne diseases, chagas, kala azar and malaria, and found artificial lighting changed the behaviour of insect vectors and thereby the modes of disease transmission. For example, the chagas parasite usually transmits through the faeces of triatomine bug when the bug bites people. But of late, people in the Amazon region have become infected by the disease after eating sugarcanes or fruits contaminated with the parasite. As artificial light surrounding houses attract triatomine bugs, they rest on trees nearby the light source instead of entering into houses and infect animals living in trees. Fruits contaminated with the faeces of these animals then transmit the disease to human beings.
Night time lighting also changes human behaviour. People stay outdoors for long hours during night, which augments their exposure to vectors like mosquito.
How is the finding important for developing countries?
The wild areas of tropical regions, mostly developing countries, teem with insects capable of transmitting infectious diseases. As rural areas next to the wilderness undergo electrification, they attract insect vectors that have so far remained away from the human establishment. At the same time, human activities in the areas increase during night, augmenting people’s exposure to insects. Both the factors may lead to spread of diseases in developing countries.
Your suggestions. We are not arguing against rural electrification, but suggest doing it carefully. There are several ways to reduce the attraction of insects to light. For example, ultraviolet light filters attract 80 per cent less insects. There are several such cheap and functional lighting systems that can minimise the impact of electrification on insects in rural areas. People who receive lighting in rural areas should also be educated about behavioural measures to minimise exposure to insect vectors.
Urgent epidemiological studies need to be carried out to understand how to reduce the impact of artificial lighting on diseasespreading insects.
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