Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Lassa fever controls need to consider human-human transmission and role of super spreaders

15.01.2015

One in five cases of Lassa fever - a disease that kills around 5,000 people a year in West Africa - could be due to human-to-human transmission, with a large proportion of these cases caused by 'super-spreaders', according to research published today in the journal PLOS Neglected Tropical Diseases.

Lassa fever is an acute viral haemorrhagic illness caused by Lassa virus. First identified in the village of Lassa, Nigeria, in 1969, the disease is thought to be transmitted to humans from contact with food or household items contaminated with rat urine or faeces.

There have also been recorded cases of human-to-human transmission within hospital settings, but until now the risk - or mode - of transmission has not been clear. Understanding the different modes of transmission and how they are affected by factors such as people's interaction with their environment is crucial for understanding the link between Lassa and changes in the ecosystem, and has important implications for public health strategies.

"Given the many competing health priorities in West Africa - exacerbated by the current Ebola epidemic - it is essential that we know the relative risk of human-to-human transmission of other potentially deadly diseases, such as Lassa fever," says first author Dr Gianni Lo Iacono from the Department of Veterinary Medicine at the University of Cambridge. "That way, public health officials can decide where to focus their public health campaigns and how to prevent or respond to potential outbreaks."

The researchers, part of the Dynamic Drivers of Disease in Africa Consortium, used mathematical modelling to analyse data from outbreaks known to be due to human-to-human chains of transmission, and calculated the 'effective reproductive number'. This number represents the number of secondary infections from a typical infected individual - for an outbreak to take hold, this number needs to be greater than one.

They compared data from hundreds of Lassa infected patients from Kenema Government Hospital, in Sierra Leone, who could have been infected either by rodents or humans, with the data from human-to-human chains. By considering the effective reproductive numbers, they inferred the proportion of patients infected by humans rather than rodents.

The researchers estimated that around one in five cases (20%) of infection is caused by human-to-human transmission. However, the study also highlighted the disproportionate number of infections that could be traced back to a small number of people, whom the researchers describe as 'super-spreaders' - rather than passing their infection on to just one other person (if at all), these individuals infected multiple others. It is not clear what makes them a super-spreader - their physiology, the environment in which they live, their social interactions or probably a combination of these factors.

Dr Donald Grant, chief physician at the Lassa ward in Kenema Governmental Hospital and co-author of the research, said: "Simple messages to the local people could change their perceptions of risk and hopefully make the difference. For example, making people aware that the virus can remain in urine for several weeks during the recovery period, could promote improved hygienic practices.

"What's more, measures to target human-to-human spread of Lassa virus can be bundled in with prevention interventions for diseases with similar transmission routes, such as Ebola and even Hepatitis B."

Professor James Wood, Head of the Department of Veterinary Medicine and senior author on the study, says: "The idea of super-spreaders in infectious diseases is not new. We've known about them since the notorious case of 'Typhoid Mary' in the early twentieth century and they've been documented for other diseases including TB, measles and SARS.

"Although we don't understand what makes someone a 'super-spreader', it highlights the importance of strict hygiene measures in preventing infection. In the case of Lassa fever, we now know that whilst the chance of transmission between humans is much lower than it is from rodents, it is still a very real risk."

Further progress has been hampered by the Ebola outbreak, which has resulted in the death of key collaborators in Kenema Hospital, which was used to nurse Ebola patients, in particular Dr Sheik Humarr Khan, who played such a key role in establishing and furthering the Lassa fever research programme.

###

The Dynamic Drivers of Disease in Africa Consortium, a multidisciplinary research project considering the linkages between zoonoses, ecosystems, health and wellbeing, is supported the UK Government through the Ecosystem for Poverty Alleviation (ESPA) research programme.

Media Contact

Craig Brierley
craig.brierley@admin.cam.ac.uk
44-012-237-66205

 @Cambridge_Uni

http://www.cam.ac.uk 

Craig Brierley | EurekAlert!

Further reports about: Ebola Veterinary Medicine diseases fever research programme

More articles from Health and Medicine:

nachricht Minimising risks of transplants
22.02.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg

nachricht FAU researchers demonstrate that an oxygen sensor in the body reduces inflammation
22.02.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Stiffness matters

22.02.2018 | Life Sciences

Magnetic field traces gas and dust swirling around supermassive black hole

22.02.2018 | Physics and Astronomy

First evidence of surprising ocean warming around Galápagos corals

22.02.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>