CABI Blogs: hand picked... and carefully sorted

Mystery disease in Ethiopia solved: linked to weed toxin

Imagine this…

A mysterious disease terrorising your community, not infectious but spreading nonetheless, and killing your relatives and neighbours. All you want to do is pack your bags and flee. Worse, when your plight comes to the attention of the health authorities, they are stumped and its not going to be easy or quick to solve.

A recent example of this kind of illness is “nodding disease” (South Sudan, Uganda, and Tanzania), which affects children 5-15 years old: they suffer epileptic seizures which causes their heads to nod, and they end up severely disabled and finally die. The USA’s Centre for Disease Control (CDC) is working to identify the cause: so far, the best guess is that it’s linked to the parasite that causes river blindness combined with an autoimmune reaction, and exposure to chemicals could predispose.

Other examples of non-communicable disease outbreaks

On Global Health, I found there are outbreaks going back to 1911 (epidemic dropsy) but more recent ones were in India,  Bangladesh, Nigeria, Brazil, China, Afghanistan and even the USA.

 What are the likely causes for these outbreaks? The body of research, as found on databases like Global Health, tells us that they could be contamination of food and water supply, exposure to chemicals or heavy metals in the environment, or even use of traditional medicine.

 Mystery liver disease in Ethiopia with a ‘happy’ ending

Can public health authorities in low-income countries solve & stop such outbreaks?   Yes. In 2005, in Ethiopia, a 4 year long outbreak of liver disease in Tseda Emba, a small village of the Tahtay Koraro district of Tigray, finally reached the attention of the Tigray Health Bureau (THB). Now, in 2012, the multidisciplinary and one-health approach they initiated has “solved” the mysterious illness, significantly reducing new cases. 

 The research work was the subject of an entire session at the recent World Congress Public Health (WCPH-2012) in Ethiopia, and is now published as 5 papers in the supplement to April 2012’s edition of Ethiopian Medical Journal (EMJ). [Abstracts to these papers will be available on Global Health]. It demonstrates the relevance of the one-health approach to public health in low-income countries and is a fascinating detective story….

Where's my ball? How practical is it to give farm animals a better environment?

There is a lot of evidence to suggest that giving animals a better environment makes them less stressed, less likely to behave abnormally, and sometimes more productive. However, most of that evidence comes from small-scale trials, and scaling improvements up to the practicalities of large farms could prove costly and burdensome.  Is it environmental enrichment a realistic option for farmers?

In an article in CAB Reviews, Laura Dixon of the Scottish Agriculture College looks at the practicalities and how environments can be improved. She says that the main approaches are through providing foraging opportunities, structural complexity, sensory stimulation or novelty, and social stimulation from other animals or humans. The type of enrichment that helps differs from animal to animal – poultry benefit from perches, while ducks prefer water troughs. Allowing birds to forage or to use water troughs and dust baths has been shown to reduce abnormal behaviour, and often leads to better growth. However, the “wilder” environment can be difficult to clean and need more maintenance, with more risk of disease.

 

He’s OK if you don’t get on the wrong side of him

Most of us have preferences such as left- or right-handedness, and tend to favour one eye over another to look down a telescope. These biases are the result of brain lateralisation, with a dominant left side of the brain leading to right handedness, and vice versa. Many animals show comparable biases. Lesley Rogers believes a better understanding of these biases could be used to improve animal welfare. Rogers, of the University of New England, Australia explains her ideas in an article in CAB Reviews.

Horses, like many animals, show side bias  (Fir0002/Flagstaffotos, see License).

The left hemisphere of the brain deals with repeated stimuli, paying attention and learning rules, whilst the right is more concerned with emergency responses to threats. Given the switch over between brain side and the part of the body that it relates to, this means that domestic chickens prefer to look at potential predators with their left eyes (associated with the right hemisphere), but to use their right eyes (and left hemisphere) to search for food, having learned rules for what is and isn’t food. Many animals respond more strongly to predators that approach them from the left.

Veterinarians Target Next Virus for Eradication

 
Following the recent eradication of rinderpest virus in cattle (see blog), the veterinary profession is contemplating which viral disease of animals should be targeted for eradication next. This is not an easy task considering the vast number of viral diseases that plague livestock animals and have devastating effects on animal health, public health and people’s livelihoods.

According to the authors of a scientific editorial (1) and a review article (2) that appeared in the recent issue of Veterinary Record published on 1st July 2011, the next livestock virus targeted for eradication could be peste des petits ruminants (PPR) virus.

Dr Michael Baron and colleagues from the Institute for Animal Health (IAH), Pirbright, UK said in their review that the Food and Agriculture Organization (FAO) and the World Organisation for Animal Health (OIE) should focus on PPR virus as the next livestock virus for eradication.

PPR virus affects sheep and goats and is closely related to the recently eradicated rinderpest virus. Cattle can also be infected with PPR virus but they do not show obvious signs of disease. PPR is circulating on the edges of the European Union, on the southern shores of the Mediterranean. Outbreaks were reported in Morocco and Tunisia in 2008 and there is evidence for its presence in Algerian sheep this year. It has also been present in Turkey for many years. PPR is the fastest growing and one of the most economically important diseases of sheep and goats, the animals that play a very important role in sustainable agriculture and development in Africa and Asia. Mortality in infected animals ranges from 10 to 90%, depending on age, breed and secondary infectious agents. Animals that survive become anorexic, their milk yield is reduced, and they are susceptible to secondary infections and abortions.

Baron and colleagues are already working on the development of a “smart” vaccine for PPR, one that leaves an antibody signature different from that created by infection with the virulent virus, so that vaccinated animals can be distinguished from animals that have been infected by virulent virus, and vice versa. They are also working on a "dip stick" test for PPR virus, similar to the one that IAH developed for the rinderpest eradication programme.

There are good reasons to believe that the eradication of PPR is an achievable goal, because the PPR virus shares a number of properties with rinderpest virus that contributed to the successful campaign to eradicate the latter, i.e. there is a safe and reliable vaccine; simple and effective diagnostic tests are available; the virus has a short infectious period, with no carrier/persistent state; transmission occurs only by close contact; and there is an economic incentive to eradicate it.

However, before a massive commitment of national and international resources for a successful eradication campaign, which would require surveillance and monitoring over a long period, a thorough evaluation of the likelihood of success of an eradication campaign, as well as its costs and benefits, is of utmost importance. Potential for eradication of other diseases such as foot and mouth disease (FMD) or rabies virus, for example, also needs to be evaluated.

CAB Direct database offers an excellent source of scientific information and is a very useful tool for evaluating potential for eradication of any viral disease of animals. It comprehensively covers world’s scientific literature from over 150 countries and in over 50 languages on all the viral diseases of animals, including PPR, FMD and rabies. CAB Direct database contains over 17000 records on rabies, over 13000 records on foot-and mouth disease and over 800 records on peste des petits ruminants.

References:

1. Anderson J., Baron MD., Cameron A., Kock R., Jones B., Pfeiffer D., Mariner J., McKeever D., Oura, CAL., Roeder P., Rossiter P. and Taylor W. (2011): Rinderpest eradicated – what next? Veterinary Record, 169: 10-11, doi: 10.1136/vr.d4011.

2. Baron MD., Parida S. and Oura CAL. (2011). Peste des petits ruminants: a suitable case for eradication? Veterinary Record, 169: 16-21 doi: 10.1136/vr.d3947.

Major Veterinary Achievement - Cattle Plague Eradicated

 The World Animal Health Organization (OIE) has declared that the cattle disease Rinderpest (also known as Cattle Plague) has been eradicated, which means that all 198 countries and territories with rinderpest-susceptible animals were free of the disease. The global disease freedom status is expected to be ratified by Ministers of Agriculture at the Food and Agriculture Organization of the United Nations (FAO) conference on 28 June.

This is the first time ever that a viral disease of animals has been eradicated. The last outbreak of Rinderpest was confirmed in 2001, when buffaloes were infected in Kenya. Rinderpest now becomes only the second viral disease ever to be eradicated, following the elimination of smallpox in the human population, which was last seen in 1977. A certain amount of pride in veterinary medicine about this achievement is almost palpable, which will undoubtedly lead into better animal health, and consequently better public health.

Rinderpest was a viral disease (caused by morbillivirus) that affected cattle, buffalo, sheep, goats, and wild animals such as antelope, giraffe, kudu, and wart hogs. The disease has killed hundreds of millions of cattle around the world for centuries. It was a highly contagious disease which could kill infected animals within days, wiping out entire herds. The disease has devastated livestock herds since Roman times, leaving economic ruins in its wake - it is speculated that the disease contributed to the downfall of the Roman empire in 4th Century. While waves of the disease regularly devastated livestock herds in Asia and Europe over history, animals elsewhere were spared the disease until 1887 when it was introduced into the Horn of Africa. A 19th-century outbreak of the disease in Ethiopia resulted in famines that wiped out one third of its human population.

In response to the devastation caused by the plague, the world's first veterinary school was founded in Lyon in 1761, which is usually regarded as the beginning of the modern veterinary profession, (our profession this year celebrates its 250th anniversary, see blog). In 1924, the World Organisation of Animal Health (OIE) was formed because of the continuing threat of Rinderpest. Control of Rinderpest was also one of the primary reasons for the creation of the FAO in 1947.

According to the FAO, Rinderpest was at its peak in the 1920s, when the disease spread from Scandinavia to the Cape of Good Hope in South Africa and from the Atlantic shore of Africa to the Philippine archipelago, with outbreaks reported in Australia and in Brazil.

The first steps to control the disease were made following the development of the "Plowright vaccine" in the 1950s. Dr Walter Plowright, a British veterinarian, and his colleagues developed an attenuated-live virus Rinderpest vaccine in Kenya. Further advances were made when the Plowright vaccine was improved in order to remain stable in the extreme heat of central Africa, and when effective control and immunization programmes were implemented.

In 1994, the Global Rinderpest Eradication Programme (GREP), headed by the FAO was launched. GREP initially focused on establishing the geographical distribution and epidemiology of the disease and later it promoted actions to contain Rinderpest within infected ecosystems and to eliminate reservoirs of infection. Once experts were satisfied that the virus had been eliminated from a region, surveillance schemes were put in place to ensure it did not return. Eradication required enormous efforts of veterinary professionals and local residents to ensure that the disease no longer existed.

Some 10 years prior to the peak of Rinderpest epidemic, CAB International was established in 1910, and since then CABI has been facilitating communication and exchanging veterinary information on animal diseases such as Rinderpest to more than 150 countries and in over 50 languages. The CAB Abstracts database currently contains more than 4600 references with abstracts on Rinderpest from 1913 to the present. The database can be searched to find the world's literature on this topic using either “Rinderpest” or “cattle plague” as search terms (4233 hits for “Rinderpest” and 3639 hits for “cattle plague”).

Further reading: Spinage, C. A. (2003). Cattle Plague. A history. 765 pp., Kluwer Academic/Plenum Publishers, New York, USA. (ISBN 0-306-47789-0)

Why Washing Your Vegetables and Hands May Not Protect You from E. coli, Staphylococcus, Salmonella…?

Following the recent outbreak of E. coli food poisoning in Germany that claimed at least 37 lives as of 14 June 2011 and still counting, numerous articles have been written, but many fundamental questions still remain unanswered.

As you will remember, contaminated Spanish cucumbers were initially blamed for the outbreak of E. coli infection, which prompted the Spanish government and farmers to vehemently deny this claim (justifiably, as it turned out) and demand compensation.

As soon as “the Spanish cucumber story” was shown to be a false alarm, tomatoes, salad and vegetable sprouts (of German origin) were declared as potential culprits. It is unclear why other vegetables, such as peppers, courgettes, mushroom, to list but a few, were kept off the list of suspects, particularly because all the laboratory tests performed so far have been inconclusive.

As time goes by, it is less likely that the source(s) of this outbreak will be identified any time soon. However, even if a contaminated vegetable (or various vegetables) is identified and successfully linked with this outbreak of E. coli in humans, identifying the pathway of contamination may prove more difficult.

While looking for potential sources of vegetable contamination with pathogenic microorganisms, I searched CAB Direct database and came across a very interesting review published 20 years ago by German Professor Strauch of the Institute of Animal Medicine and Hygiene, University of Hohenheim, which explains how pathogens may contaminate food crops. He warned about the potential of pathogenic organisms to cross from manure or sewage into food crops and suggested that “the agricultural utilization of hygienically dubious sewage or sludge poses a risk for the whole national economy.”

In his 1991 review “Survival of pathogenic microorganisms and parasites in excreta, manure and sewage sludge” (Rev Sci Tech. 1991 Sep;10(3):813-46), Strauch also reported that two groups of researchers had found that pathogenic organisms can be taken up by crops that are used in human and animal nutrition.

Once pathogenic microorganisms are incorporated into crops (including vegetables), washing the outside of fresh vegetables is of little benefit, because all the pathogens from the sludge (bacteria, viruses and parasites) are inside the plant.

This song could go viral

Venezuelan equine encephalomyelitis (VEE) is not often referenced in song, but The Crab Hole Mosquito Blues has just been released online in text and audio in the journal Emerging Infectious Diseases, charting the spread and control of the disease, which affects horses and people.

An alphavirus, such as VEE (Center for Disease Control)

The song describes the discovery that Deinocerites pseudes, the crab hole mosquito, found along the Pacific coast of Central America was a vector for the VEE virus.  Scientists at the Middle America Research Unit (MARU), Ancon, Panama Canal Zone wrote the song during an outbreak of VEE that affected Central America, Mexico, and the USA. The scientists managed to characterise the spread of different antigenic forms of equine and associated human disease throughout the Americas.  The research by MARU and others led to the development of an effective vaccine, allowing the disease to be controlled.

It’s not just puppy fat

While it’s a well-known piece of perceived wisdom that owners look like their dogs, there is evidence that obese owners are more likely to have obese dogs. Writing in CAB Reviews, Ian Bland and Julian Hill discuss the importance of owner’s perceptions of exercise and diet in terms of controlling obesity in dogs.
It is hard to be sure what the level of dog obesity is, as there is no BMI equivalent, and estimates based on owner assessments are different to those conducted by vets, but the trend is upwards.

 

Do current e-book models help or hinder the migration from print to online?

It seems that in 2010 we have been finally witnessing the “tipping point” for e-books, with more and more libraries making a positive choice to purchase e-books instead of print editions.  Do publishers’ business models make this migration easier for libraries to implement, or actually place obstacles in their way?  E-book collections versus individual title selection; annual subscriptions versus one-time purchases; simultaneous users versus unlimited site-wide licensing; availability or not of online textbooks … We asked librarians from three very different institutions for their views. Read what they said and add your own opinions below.

Wild chimps outwit bushmeat hunters

Across Africa, people often lay snare traps to catch bushmeat, killing or injuring chimps and other wildlife. But a few chimps living in the rainforests of Guinea have learnt to recognise these snare traps laid by human hunters. More surprisingly, the chimps actively seek out and intentionally deactivate the traps, setting them off without being harmed.