Featured Research

from universities, journals, and other organizations

HIV-1 Spread Through Six Transmission Lines In The UK

Date:
March 24, 2005
Source:
University College London
Summary:
Contrary to the prevailing belief that the HIV epidemic in the UK can be traced back to one source, a new study suggests that HIV spread via at least six independent virus introductions and subsequent transmission chains. The findings, published in the latest issue of the Proceedings of the National Academy of Sciences, also suggest that antiviral therapy has not had a significant impact on the growth of the epidemic and that changes in sexual behaviour have been more effective in slowing the spread of the disease.

Contrary to the prevailing belief that the HIV epidemic in the UK can be traced back to one source, a new study suggests that HIV spread via at least six independent virus introductions and subsequent transmission chains. The findings, published in the latest issue of the Proceedings of the National Academy of Sciences, also suggest that antiviral therapy has not had a significant impact on the growth of the epidemic and that changes in sexual behaviour have been more effective in slowing the spread of the disease.

The collaborative study led by University College London (UCL) scientists found that HIV-1 subtype B spread through the UK via at least six large transmission chains of men having sex with men, suggesting separate introductions of subtype B strains into the UK in the early-to-mid 1980s. After an initial period of exponential growth in infection rates, the spread generally slowed in the early 1990s, more likely from changes in sexual behaviour than from reduced infectiousness resulting from antiretroviral therapy.

The study by UCL, the Health Protection Agency and the University of Oxford statistically analysed the epidemic history of the HIV-1 subtype B strain from sampled gene sequence data. Molecular data on HIV-1 has become increasingly available since the introduction of routine HIV-1 gene sequencing for drug resistance. Scientists used this data to follow the changing number of infected individuals through time and estimate the demographic parameters shaping the epidemic.

During the exponential growth phase, the transmission chains had an average growth rate of a doubling of the number of people infected each year, similar to that estimated for the US subtype B epidemic during the 1980s. The average number of infections across each chain was 445, approximately 2.5% of the infected population at the time. This trend is remarkably similar to the values for the US epidemic, where the number of transmitted infections and prevalence in 1995 reached 5000 and 200,000 infections respectively.

The most recent transmission chain identified by the study shows a faster doubling time in 2003 than the other five. Current surveillance data shows a recent increase in infections amongst homosexual men in the UK , which may partly have come through this chain.

Dr Deenan Pillay of UCL's Centre for Virology says: “Our study suggests that the HIV-1 subtype B epidemic currently circulating the UK is made up of at least six established chains of transmission, introduced in the early and mid 1980s. This goes against the prevailing belief that one initial entry of HIV-1 was responsible for the spread of the epidemic.

“Since 1990 there have been important changes in Britain's social attitudes and awareness of HIV-1 and AIDS. Despite a very recent increase in high-risk behaviour among men having sex with men, a significant increase in condom use has been reported since 1990, which could explain the equilibrium reached for the number of infections.

“Antiretroviral therapy may also have impacted on transmission rates, but our evidence does not demonstrate this. You would expect growth rates to decrease in the late rather than early 1990s around the time that potent therapy became widely used if this was the case. Instead, we see little correlation between widespread availability of treatment and reduction of transmission. This is highly pertinent to the recent increase again in new HIV-1 diagnoses within the UK .

“Our study also contradicts assumptions that the HIV-1 epidemic is composed of smaller, independent epidemics defined by risk group, where we have found evidence for at least six larger sub-epidemics, which HIV monitoring, prevention and treatment programmes may want to take into account when developing new initiatives.”

More than 57,700 people in Britain have been infected with human immunodeficiency virus type 1 or HIV-1 since the first identification of A ID S in 1982. Despite a recent increase in heterosexually acquired infections within the UK , predominantly originating in sub- S aharan A frica , one of the most prevalent clades (subtypes) of virus within the country remains subtype B, which is mainly transmitted through sex between men. Very little is known about how subtype B successfully invaded the British population, and more importantly, how the virus has subsequently spread and evolved.

However, given that the first UK cases of AIDS reported in 1982 were probably infected within a window of 10 years prior to that time, the currently circulating strains may not represent the first HIV-1 lineages within the UK . If earlier strains existed they may have been unsuccessful in sustaining transmission to the present, although the absence of older strains could also reflect a sampling bias in this study.


Story Source:

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


Cite This Page:

University College London. "HIV-1 Spread Through Six Transmission Lines In The UK." ScienceDaily. ScienceDaily, 24 March 2005. <www.sciencedaily.com/releases/2005/03/050323150912.htm>.
University College London. (2005, March 24). HIV-1 Spread Through Six Transmission Lines In The UK. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2005/03/050323150912.htm
University College London. "HIV-1 Spread Through Six Transmission Lines In The UK." ScienceDaily. www.sciencedaily.com/releases/2005/03/050323150912.htm (accessed July 28, 2014).

Share This




More Health & Medicine News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

$15B Deal on Vets' Health Care Reached

$15B Deal on Vets' Health Care Reached

AP (July 28, 2014) A bipartisan deal to improve veterans health care would authorize at least $15 billion in emergency spending to fix a veterans program scandalized by long patient wait times and falsified records. (July 28) Video provided by AP
Powered by NewsLook.com
Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
Powered by NewsLook.com
West Africa Gripped by Deadly Ebola Outbreak

West Africa Gripped by Deadly Ebola Outbreak

AFP (July 28, 2014) The worst-ever outbreak of the deadly Ebola epidemic grips west Africa, killing hundreds. Duration: 00:48 Video provided by AFP
Powered by NewsLook.com
Trees Could Save More Than 850 Lives Each Year

Trees Could Save More Than 850 Lives Each Year

Newsy (July 27, 2014) A national study conducted by the USDA Forest Service found that trees collectively save more than 850 lives on an annual basis. Video provided by Newsy
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:
from the past week

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