Trains within Mumbai and its surrounding area cater to around seven million travellers a day. The transport systems of India allow for a faster route to work. They may also be considerably increasing the spread of disease.
Many trains — particularly in the densely populated urban areas — hold far more passengers than their intended capacity. By packing people together in such a way, the risk of an infection spreading rises considerably.
“A single individual with the flu may sneeze. By sneezing, they may expose multiple individuals around themselves to the influenza virus”
In a train containing several hundred passengers, a single individual with the flu may sneeze. By sneezing, they may expose multiple individuals around themselves to the influenza virus. These individuals may be infected by the virus, or they may simply harbour it on their clothes and hands, spreading the virus further.
Each person infected in this event will go about their day as usual, taking the virus and potentially spreading it to their place of work, as well as on any subsequent form of public transport. As these people return from work to suburban areas they take any infections with them. In this manner, any disease outbreak may spread across the entirety of an urban metro within hours.
An example of the spread of disease coinciding with urbanisation is chikungunya. Over the last three years the disease is thought to have increased in prevalence by 390 percent. Before this period disease cases were steadily decreasing since 2010.
The continued spread of the disease despite various attempts to crack down on mosquito populations is testament to the degree to which the Aedes Aegypti mosquito is adapted to urban environments. They can thrive in any area with stagnant water, which is often provided in abundance in areas where waste is dumped, or in artificial containers associated with human dwellings.
“It is people, rather than the mosquitoes, that spread the disease to new communities and areas”
The World Health Organization has determined that each individual mosquito remains relatively close to its place of birth, flying an average of only 400 metres away from this location over the course of its lifespan. This fact suggests that it is people, rather than the mosquitoes, that spread the disease to new communities and areas.
Uninfected mosquitoes may draw blood from an individual infected with dengue fever, chikungunya or malaria, thereby infecting the mosquito and allowing it to spread the disease further. Due to the the ease of travel for people within the urban environment, this can mean new infections can occur wherever there are mosquito populations.
Innovation and the use of big data has been claimed to be the best way of addressing the spread of disease in urban areas. More extensive use of mosquito control measures that can be used and monitored down to the local authority level may reduce disease figures by limiting spread.
Use of big data could provide detailed information of the flow of people, analysing all possibly transport routes and comparing these figures to disease outbreak information. By doing this, high risk areas and routes may be identified and monitored with priority.