Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Insects implicated in the evolution of new human infectious diseases

25.10.2004


Insects and other invertebrates are the arena for the evolution of new infectious diseases in humans, new research shows.



Scientists now believe that not only are insects the carriers of some existing diseases but they are also the vehicle where recently emerging highly infectious diseases, such as the plague that killed millions in the 14th and 17th Centuries, evolve. Writing in the October edition of Nature Reviews: Microbiology, the researchers point to the large reservoir of diseases in invertebrates, such as fleas and nematode worms, which are currently harmless to humans, but which could evolve quickly into a range of new diseases.

As part of their research, Dr Nick Waterfield and Professor Richard ffrench-Constant (correct) from the University of Bath, and Professor Brendan Wren, from the London School of Hygiene and Tropical Medicine, are studying a new disease-causing (pathogenic) bacterium that has been identified in about a dozen people in the USA and Australia. Their study looked at the bioluminescent bacterium, Photorhabdus asymbiotica, which cause pustulent sores to appear on parts of sufferers¡¦ bodies. The researchers suspect that this new bacterium evolved recently from a well-known bacterium, Photorhabdus luminescens, which kills insects with the help of nematode worms.


This family of bacteria are known as Photorhabdus (glowing rods) because they are the only terrestrial bioluminescent bacteria. The bodies of insects killed by Photorhabdus luminescens infection are left luminous. Genome studies have found close similarities between the plague-causing bacterium, Yersinia pestis, and its ancestor, Yersinia psuedotuberculosis, which has been shown to be capable of causing disease insects, at least in the laboratory. Evidence suggests that the plague could have evolved from a close insect-pathogenic ancestor as little as 1,500 years ago, an eye blink in evolutionary time, suggesting that similar scenarios are possible for other insect-associated microbes.

The researchers suggest the reason that unusual infections, such as those caused by Photorhabdus asymbiotica, are not currently a large problem is that there are a range of antibiotics to treat them and insecticides that help suppress invertebrate numbers. However, they warn it could be only a short time before the parallel problems of insect resistance to insecticides and bacterial resistance to antibiotics unite to throw up new diseases that doctors will have difficulty controlling.

In-built similarities between human and insect immune systems also mean that any diseases that have successfully evolved to infect insects already have a head start if they attack people. ¡§Most scientists are looking at diseases of farm animals as the biggest threat to humans. Insects are numerous and reside in close proximity to man, yet they have been generally ignored as a potential source of microbes that could be harmful for man,¡¨ said Dr Waterfield. ¡§As well as passing microbes directly into our bloodstream when they bite us, insects can also act as a reservoir to ¡¥cook up¡¦ future human diseases.

¡§Understanding the mechanism that the bacteria use to change their disease-causing ability is important if we are to successfully treat emerging infectious diseases before they get out of control and become epidemics. ¡§There are countless species of bacteria in insects, and sometimes they cause emerging infectious diseases by becoming harmful to people ƒ{ in other words by evolving into a new type of disease which we haven¡¦t seen before. ¡§The species of bacteria may have been around for centuries, but it is just that a new strain evolves that is suddenly able to infect humans as well as other animals. ¡§The picture is further complicated by climate change, which seems to be altering the range of places insects can survive and breed, bringing new insects which can carry devastating diseases such as malaria into the Northern hemisphere.¡¨

In the case of Photorhabdus luminescens, the infection is naturally resistant to several antibiotics but the relapsing infection can be combated using repeated administration of certain drugs.

The researchers predict that the failure of automated hospital diagnostic machines to recognise this unusual bacterium means that many more cases of this new infection may exist. This is likely to be particularly true for the developing world, where doctors may diagnose the sore as a bad ulcer and treat immediately with antibiotics. Now that researchers are actively looking for Photorhabdus asymbiotica infection, they are beginning to find cases in countries in Asia.

Andrew McLaughlin | EurekAlert!
Further information:
http://www.bath.ac.uk/pr/releases/humaninfectionsfrominsects.htm
http://www.bath.ac.uk

More articles from Agricultural and Forestry Science:

nachricht Cereals use chemical defenses in a multifunctional manner against different herbivores
06.12.2018 | Max-Planck-Institut für chemische Ökologie

nachricht Can rice filter water from ag fields?
05.12.2018 | American Society of Agronomy

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

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

Im Focus: Regensburg physicists watch electron transfer in a single molecule

For the first time, an international team of scientists based in Regensburg, Germany, has recorded the orbitals of single molecules in different charge states in a novel type of microscopy. The research findings are published under the title “Mapping orbital changes upon electron transfer with tunneling microscopy on insulators” in the prestigious journal “Nature”.

The building blocks of matter surrounding us are atoms and molecules. The properties of that matter, however, are often not set by these building blocks...

Im Focus: University of Konstanz gains new insights into the recent development of the human immune system

Scientists at the University of Konstanz identify fierce competition between the human immune system and bacterial pathogens

Cell biologists from the University of Konstanz shed light on a recent evolutionary process in the human immune system and publish their findings in the...

Im Focus: Transformation through Light

Laser physicists have taken snapshots of carbon molecules C₆₀ showing how they transform in intense infrared light

When carbon molecules C₆₀ are exposed to an intense infrared light, they change their ball-like structure to a more elongated version. This has now been...

Im Focus: Famous “sandpile model” shown to move like a traveling sand dune

Researchers at IST Austria find new property of important physical model. Results published in PNAS

The so-called Abelian sandpile model has been studied by scientists for more than 30 years to better understand a physical phenomenon called self-organized...

Im Focus: Cryo-force spectroscopy reveals the mechanical properties of DNA components

Physicists from the University of Basel have developed a new method to examine the elasticity and binding properties of DNA molecules on a surface at extremely low temperatures. With a combination of cryo-force spectroscopy and computer simulations, they were able to show that DNA molecules behave like a chain of small coil springs. The researchers reported their findings in Nature Communications.

DNA is not only a popular research topic because it contains the blueprint for life – it can also be used to produce tiny components for technical applications.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Global Legal Hackathon at HAW Hamburg

11.02.2019 | Event News

The world of quantum chemistry meets in Heidelberg

30.01.2019 | Event News

Our digital society in 2040

16.01.2019 | Event News

 
Latest News

The Internet of Things: TU Graz researchers increase the dependability of smart systems

18.02.2019 | Interdisciplinary Research

Laser Processes for Multi-Functional Composites

18.02.2019 | Process Engineering

Scientists Create New Map of Brain’s Immune System

18.02.2019 | Studies and Analyses

VideoLinks
Science & Research
Overview of more VideoLinks >>>