Featured Research

from universities, journals, and other organizations

Tuberculosis Spreads Through Crowded City Buses, Cornell Researcher Reports

Date:
February 1, 1999
Source:
Cornell University
Summary:
The crowded metropolitan bus system in Buenos Aires could be responsible for 30 percent of new cases of tuberculosis in the city, a new study shows. According to a Cornell University biomathematician, taking public transportation "is a considerable component of transmission and probable evolution of the disease."

ITHACA, N.Y. -- The crowded metropolitan bus system in Buenos Airescould be responsible for 30 percent of new cases of tuberculosis in thecity, a new study shows. According to a Cornell Universitybiomathematician, taking public transportation "is a considerable componentof transmission and probable evolution of the disease."

Related Articles


Tuberculosis has been on the increase around the world since 1985after recessing in incidence for several years. It now results in 8million deaths a year. The leading causes of infection are thought toinclude global movements of people, urban crowding, poverty and the HIVvirus, which appears to accelerate tuberculosis infection in HIV-positiveindividuals.

Speaking during a session on the mathematics of epidemics anddisease at the annual meeting of the American Association for theAdvancement of Science in Anaheim, Calif., last week, CarlosCastillo-Chavez, Cornell professor of biometry and statistics, providedinsights into the discovery that crowded urban buses can act as incubatorsfor tuberculosis.

Castillo-Chavez noted that there is "a lot of evidence" thattuberculosis is spread by airplane travel in which close proximity ofpassengers provides a source of possible infection. In fact, he said,"living in a global economy," and the associated international travel,"might even accelerate the transmission of tuberculosis."

Until now, there have been few studies of increased contact ratesdue to the use of public transportation in large urban areas such as BuenosAires and Mexico City. Castillo-Chavez said that he and his colleagues inthe United States, Argentina and Mexico concluded from their study ofBuenos Aires neighborhoods that "a person who takes a bus regularly islikely to have more contacts and have a greater chance of infection."

Argentina, Castillo-Chavez said, has a tuberculosis incidence rateof 42 people per 100,000 of population, but in the inner city of BuenosAires, the incidence rate shoots up to more than 160 people per 100,000.

Buenos Aires is one of the most crowded cities in the world, with apopulation of about 12 million. Castillo-Chavez cited a recent studyshowing that about 18 million trips are made daily by train, subways, taxi,private car and on the area's 295 bus lines. The bus system, he said, dailycarries 9.2 million passengers, or 82 percent of the movement in publictransportation and 50 percent of the area's total transportation trips.

Four main factors, he noted, are essential to an outbreak oftuberculosis: A large proportion of susceptible individuals, a disseminatorof the microorganism "Mycobacterium tuberculosis", overcrowding and a lackof ventilation. "All are present in a big city like Buenos Aires," he said.

Researchers at the Universidad de Belgrano in Buenos Airesattempted to calculate the probability of being infected by thetuberculosis bacillus on a bus by keeping track of the numbers of peopletaking a bus in a particular neighborhood and how long they spent on thebus, Castillo-Chavez reported at the AAAS meeting. It was found that onthe average, 100 people an hour entered and left the bus. From this theycalculated that for every one hour of travel there was one tuberculosisinfection for every 1,000 travelers.

Bus travel, the Buenos Aires researchers concluded, could beresponsible for about 30 percent of new cases of tuberculosis.

"This is an important computation about the role of tuberculosis,"Castillo-Chavez said. Computer simulations indicate that "you get moredisease in poor neighborhoods where more people take the bus; you canactually see that the contribution by bus takers is very critical," headded.

The Cornell researcher noted that with the increased use of publictransportation, particularly by the disadvantaged, "we create moreopportunites for opportunistic infections."

Castillo-Chavez' study was carried out in conjunction with AngelCapurro and Juan Aparicio from the Universidad de Belgrano.


Story Source:

The above story is based on materials provided by Cornell University. Note: Materials may be edited for content and length.


Cite This Page:

Cornell University. "Tuberculosis Spreads Through Crowded City Buses, Cornell Researcher Reports." ScienceDaily. ScienceDaily, 1 February 1999. <www.sciencedaily.com/releases/1999/02/990201072734.htm>.
Cornell University. (1999, February 1). Tuberculosis Spreads Through Crowded City Buses, Cornell Researcher Reports. ScienceDaily. Retrieved January 29, 2015 from www.sciencedaily.com/releases/1999/02/990201072734.htm
Cornell University. "Tuberculosis Spreads Through Crowded City Buses, Cornell Researcher Reports." ScienceDaily. www.sciencedaily.com/releases/1999/02/990201072734.htm (accessed January 29, 2015).

Share This


More From ScienceDaily



More Health & Medicine News

Thursday, January 29, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Malnutrition on the Rise as Violence Flares in C. Africa

Malnutrition on the Rise as Violence Flares in C. Africa

AFP (Jan. 28, 2015) Violence can flare up at any moment in Bambari with only a bridge separating Muslims and Christians. Malnutrition is on the rise and lack of water means simple cooking fires threaten to destroy makeshift camps where people are living. Duration: 00:40 Video provided by AFP
Powered by NewsLook.com
Poultry Culled in Taiwan to Thwart Bird Flu

Poultry Culled in Taiwan to Thwart Bird Flu

Reuters - News Video Online (Jan. 28, 2015) Taiwan culls over a million poultry in efforts to halt various strains of avian flu. Julie Noce reports. Video provided by Reuters
Powered by NewsLook.com
Media Criticizing Parents For Not Vaccinating Children

Media Criticizing Parents For Not Vaccinating Children

Newsy (Jan. 28, 2015) As the Disneyland measles outbreak continues to spread, the media says parents who choose not to vaccinate their children are part of the cause. Video provided by Newsy
Powered by NewsLook.com
Shark Bite Victim Making Amazing Recovery

Shark Bite Victim Making Amazing Recovery

AP (Jan. 27, 2015) A Texas woman who lost more than five pounds of flesh to a shark in the Bahamas earlier this month could be released from a Florida hospital soon. Experts believe she was bitten by a bull shark while snorkeling. (Jan. 27) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins