Tweet23-07-2010 om 12:26 by Sueli Brodin

Do you know the strange feeling when everything that happens around you at certain periods of time somehow seems to be connected?

This past week for example definitely fell under the theme of parasites and mosquito bites.

It all started when my children woke up one morning, their arms and legs covered with  red itchy bumps.

“Why do mosquitoes bite us?” they moaned.

“Because you’re so sweet,” my husband said. And he added, teasing: “See, they don’t bite your mother.”



That same day we heard that my brother in law Peter, who moved to Sierra Leone some 18 months ago with his wife Annette, had caught malaria and had been very sick. Annette herself contracted the disease last fall.

Not only that, but Peter fell ill just as Annette had returned to Sierra Leone after recovering from a severe and painful bacterial eye infection that had to be treated in the Netherlands.

When I found out that a new exhibition on the subject of parasites was going to open at the Natural History Museum in Maastricht, with a lecture on malaria on Sunday afternoon by a leading Dutch medical entomologist, it almost looked as if the event had been put together especially for us.



The exhibition started off with two short presentations on parasites.

The first speaker, from the Municipal and Regional Health Service GGD, defined a parasite as an organism that grows, feeds, and is sheltered on or in a different organism while contributing nothing to the survival of its host.

He introduced the concept of parasitism with two thought-provoking quotes:

“Parasitism is the most popular animal lifestyle on the planet.”
Kevin Lafferty

“We humans are the greatest of earth's parasites.”
Martin H. Fischer

He then proceeded with an slide presentation of the main types of parasites which can infect humans. One of the images dealt with the parasitic worm responsible for the river blindness disease, an endemic ailment in many African countries. This was of particular interest to my husband and me, because during their first stay in Sierra Leone in the early 1980s, Peter and Annette used to run  a development project aimed at teaching agricultural methods to people who had been left blind after being infected by a worm that breeds in fast-flowing rivers and is spread by a certain type of black fly.



My son Tim felt personally concerned by the second talk about ticks and tick bite prevention. When the speaker asked who in the audience had been bitten by a tick, he was among those who raised their hand. He explained out loud that he had discovered a tick under his armpit last month and that he had extracted it on his own.

I was surprised to learn that the number of tick bites has considerably increased in the past few years in the Netherlands, especially in Brabant, North-Groningen and Limburg, and that  25 percent of ticks in the Netherlands carry the Borrelia bacteria which causes Lyme disease.



The exhibition, entitled Parasieten!: Slinkse gluiperds ( Parasites!: shrewd sneaks), describes itself as “the most distasteful and terrifying exhibition in the history of the Natural History Museum in Maastricht.” It showcases many types of parasites, which can be divided into two categories: endoparasites, which live inside the host, or ectoparasites, which stay on the surface of the host.



Even if parasitism is a widespread form of life, there is something repulsive about it, because it evokes the ideas of “stealing”, “profiting without giving in return”, “existing at the expense of”.

The Tongue eating louse is a particularly creepy parasite. It is a crustacean that enters the mouth of a fish through its gills and attaches itself at the base of the tongue. It extracts blood from the tongue until the organ atrophies and ends up taking its place by attaching its own body to the muscles of the tongue stub. The fish is able to use the parasite just like a normal tongue. The parasite is apparently the only known case of a parasite functionally replacing a host organ.



Foxes can be carriers of the fox tapeworm, which causes a very serious and potentially fatal infection in humans.

The regional newspaper Dagblad De Limburger has been covering the story of a kit that was spotted on several occasions at the swimming pool in my neighbouring town of Meerssen earlier this month. The young animal was looking for food and was attracted by the leftovers from the pool’s daily visitors.

The paper reported that the town authorities were concerned about the risks of tapeworm infection and was considering having the animal shot. The swimming pool management and various local animal welfare organisations however protested against the measure, because there was no indication that the fox was infected and because foxes are a protected species and can only be shot under rare circumstances, when every other more animal friendly solution has failed.

The story finally came to a good end this week when staff from the Wildlife Protection Centre in Limbricht managed to catch the kit and take it to safety. I was relieved to read on the Centre’s website that the little fox will be released as soon as possible back into its natural habitat, further away from humans.



The official opening of the exhibition ended with an exposé by malaria specialist Bart Knols, who used a compelling animation film to explain the way in which malaria parasites are transmitted to humans via the bites of infected mosquitoes.

Knols continued with a lively and well illustrated Pecha Kucha-style history of malaria, focusing on striking examples of incidents when outbreaks of malaria literally changed the course of history.

I was particularly fascinated by the story of the Walcheren Fever. According to Knols, this was the first example of biological warfare, when the French troops of Napoleon released malaria parasites in 1809 on British troops stationed on the Dutch island of Walcheren, causing thousands of them to become sick and perish.

I was so impressed by Knols’ presentation that I googled his name when I came back home and went from surprise to surprise as I discovered that the scientist was born and raised in Meerssen and that his extensive research on malaria had earned him many prestigious prizes, including the 2006 Ig Nobel Prize in biology for showing that “the female malaria mosquito Anopheles gambiae is attracted equally to the smell of Limburger cheese and to the smell of human feet.”

The Wikipedia entry about Limburger cheese even mentions that “as a direct result of these findings Limburger cheese has now been placed in strategic locations in the nations of Africa to combat the epidemic of malaria.”

In the meantime the fight against malaria continues and the latest breakthrough looks promising: several media reports announced last Friday that researchers at the University of Arizona have created a malaria-proof mosquito, a genetically modified insect that is incapable of transmitting the disease to humans.

As for us, it looks like we might be wise to buy a good reserve of smoothing anti-itch cream: the entire French coastal region where we will be spending our summer holiday is reportedly plagued by mosquitoes!

The exhibition Parasites! will be running at the Natural History Museum in Maastricht until 7 November 2010.

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