Parasitology

Publication Analysis 2007-2013
by Kathleen Gransalke, Labtimes 03/2015


View the Tables: Europe...and the World, Most Cited Authors...and Papers

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Trypanosome in hepatic vessel of mouse. Photo: G. Vanwalleghem, D. Monteyne and D. Pérez-Morga, CMMI, Laboratory of Molecular Parasitology, Université Libre de Bruxelles, Belgium

England stands head and shoulders above the rest of Europe, dominating both the nations’ as well as the most-cited authors’ ranking. Unsurprisingly, the hottest topic is malaria.

There must be something about the parasitic way of life. Not wasting a single thought on acquiring food and solely focussing on the important thing in life – reproduction – must, somehow, be very attractive. In return, giving up independence is apparently a price parasites are willing to pay. Hence, quite a number of creatures from all branches of the tree of life have opted for it – there are parasitic plants, fungi, worms, crustaceans, protozoa, bacteria – you name it.

As always, there are individuals with more or less harmless intentions – for instance, the tongue-eating louse, Cymothoa exigua, replaces a fish’s tongue, without the fish noticing any difference. But there are also those with more sinister plans. They take control over their host and its behaviour. Toxoplasma gondii, an intracellular protozoan, is one such critter. Infected rodents lose their natural fear of cats – you can imagine the rest. But what happens in the brains of these mice? Researchers from the Indiana University School of Medicine studied the acetylome of T. gondii-infected cortical astrocytes, glial cells that make up the blood-brain barrier, and found that the level of acetylation was changed in a number of proteins (PLoS ONE, 10(3): e0117966). “We don’t know the impacts of these changes yet, but these discoveries could be particularly significant in understanding how the parasites persist in the brain and how this ‘rewiring’ could affect behaviour in both rodents and humans,” lead author William Sullivan stated in a press release.

All these are fascinating stories and we haven’t even mentioned the parasites that turn their hosts into zombies. But apparently, to make it big in Parasitology and secure a spot in the Lab Times ‘list of honour’, studying malaria and its associated protozoan parasite, Plasmodium spp., seems to be a big advantage.

Former colonial powers perform strongly

Before we get started with the nations ranking, a few more words about the procedure. As mentioned before, we use Thomson Reuters’ Web of Science database for our publication analysis and the numbers for the nations’ ranking is based on so-called “expert journals”, as it’s impossible to retrieve parasitologically-themed papers from multi-disciplinary journals, like Nature or Science. The expert journals, filed under “Parasitology” by Web of Science, include titles such as Trends in Parasitology, PLoS Neglected Tropical Diseases and Ticks and Tick-Borne Diseases. For our top 30 most-cited authors, however, all journals and papers were permitted, no matter where they had been published. For simplicity and to avoid overlapping, we decided to leave out all virus researchers from our publication analysis. Virus researchers are referred to the virus research ranking, which we last did in 2012 (LT 7-2012).

So, what papers, from which nation gathered the most citations? This time, the answer is pretty clear. With more than 60,000 citations and 3,800 papers, the number one spot is firmly in English hands. Runner-up, France, and Germany, in third place, can’t even remotely keep up. Parasites, especially the malaria parasite, prefer tropical climates and hence, it’s hardly surprising that former colonial powers like England and France perform strongly in this publication analysis. Some old connections must still exist. Nordic countries, in contrast, play only a minor role. Sweden (10th) is the North’s best, while Finland (22nd) didn’t even make it into the top 20 this time. Portugal (13th), also a former colonial power, did remarkably well, as did the Czech Republic (12th). When it comes to citations-per-article, no nation stands out that clearly. The best here are The Netherlands, Switzerland and Ireland.

Brazil: breeding ground for top parasitology research

Worldwide, European parasitologists published more articles, gathering more citations, than their US peers. But the citation-per-article ratio, once again, argues for the colleagues from across the pond (13.3 vs 16.0). In third spot is not one of the usual suspects like Australia or China but Brazil. The Amazon rainforest is well-known for its biodiversity, this, of course, also applies to parasites: Plasmodium, Leishmania, Schistosoma, Trichuris, they are all there, waiting for a new victim. By the way, the most common parasitic infection in the area is soil-transmitted helminthiasis (234 million cases in 2002) and Chagas disease (8 to 9 million cases between 2002 and 2007) (PLoS Negl Trop Dis, 2(9): e300).

Let’s move on to the top 5 papers in Parasitology research. For this top list, we had to exclude quite a number of articles co-authored by European parasitologists. Their reprint address was either in the USA or in tropical countries like Thailand, Kenya or Malaysia. Inconsistent with our earlier statement, malaria is the topic of only one top paper (4th place). And it’s not even the principal topic of the article that deals with a genetic variant that protects against pneumococcal disease, bacteremia, malaria and tuberculosis. Other highly-cited research includes genomic analysis of the blood fluke, Schistosoma mansoni, and the three protozoan Leishmania species, L. infantum, L. braziliensis and L. major. The top five is completed by two studies, describing the best ways to treat leishmaniasis and soil-transmitted helminth infections.

Parasites are found everywhere but those that need the most scientific attention because they kill people, often call the tropics home. Hence, many parasitologists spend at least part of their research life on-site, in Africa or Asia, to observe their research subject in its natural habitat. Intimate research collaborations also exist. For over two decades, the Wellcome Trust and the University of Oxford has been partner to the Kenya Medical Research Institute (KEMRI), for instance. Starting with only 12 people in 1989, the KEMRI-Wellcome Trust Research Programme now has several hundred staff, among them two of our top 30 most-cited parasitologists, Kevin Marsh (6th) and Robert Snow (8th).

Marsh and Snow are only two of altogether 18 researchers based at Universities and Institutes in England – demonstrating England’s superiority in Parasitology once more. Half of these 18 researchers are affiliated with the University of Oxford. Also, five scientists at the London School of Hygiene and Tropical Medicine made it into our top 30. As did parasitologists, working at Imperial College London, the Liverpool School of Tropical Medicine and the Wellcome Trust Sanger Institute, at Hinxton. Rather unusually, another tropical institute is situated in Switzerland. Founded in 1943, the Swiss Tropical and Public Health Institute in Basle has become a major player in parasitology research – four scientists made it into our top 30. In addition, there are four parasitologists from Spain, and one each from The Netherlands, Belgium and Germany.

Malaria researchers outnumber worm and tick experts

As mentioned earlier, malaria and the malaria-causing parasite, Plasmodium, is the hottest topic in Parasitology research in Europe. Or at least, the one that got researchers studying it the most citations. Malaria researchers do everything in their power to get a grip on the disease. They look at epidemiology, pathophysiology and treatment of the disease (White, 1st; Day, 2nd; Nosten, 4th), they develop better drugs (Brun 5th) or vaccines (Greenwood, 9th; Sauerwein, 17th; Kremsner, 25th), study its transmission dynamics (Drakeley, 15th; Ghani, 20th), investigate protective immune responses (Marsh, 6th; Riley, 19th; Conway, 30th) or work on plans to eradicate it once and for all (Alonso, 11th; Tanner, 16th).

Eight of our top 30 most-cited parasitologists in Europe are not that interested in malaria, though. Jürg Utzinger (3rd) and Jennifer Keiser (18th), both at the above mentioned Swiss Tropical and Public Health Institute, and Matthew Berriman (7th) are more into parasitic worms. The former pair study the diseases caused by, for instance, Schistosoma and Trichuris. Berriman looks into the wormy parasites’ genomes. Parasites do not only cause disease in humans, that’s why Jose de la Fuente (23rd) and Christian Gortazar (28th) specialised in veterinary parasitology, with a focus on tick-borne diseases in wildlife.

Although it might not garner as many citations as other disciplines, like cancer or cardiovascular research, understanding parasites and the diseases they cause is not less important, given the fact that so many people are affected worldwide. Clearly, a lot of work still lies ahead for parasitologists worldwide, especially regarding the so-called neglected tropical diseases, like leishmaniasis, sleeping sickness, schistosomiasis and soil-transmitted helminthiasis. Because even for the well-researched malaria, the battle is still far from being won.


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Last Changed: 25.05.2015




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