Parasitology in Africa
Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"
Something completely different! Thursday the 20th September I was visiting my friend Dr. Ali Halajian at the University of Limpopo. Dr. Ali is an expert on parasites, Senior Researcher at Parasitology laboratory, SARChI Research Chair in Ecosystem Health, having been involved in discovery of several new species in South Africa in the past 7 years. I went to see for myself at the lab how science is actually being conducted. Parasitology is a field that may seem rather yucky, but it's vital. Parasites are living beings, too, often with incredible life cycles. And they affect the more charismatic critters we tend to care about like birds and mammals. Humans are affected by parasites, too … some make the jump from animals to people. Then also, animals which we use for food are affected, causing problems in food production and quality and, again, possible infection of people (zoonoses). Parasite research is vital for assessing overall health of entire ecosystems.
The problem is that because of this work so lacking glamour, there is a huge shortfall of scientists actually doing research on parasites. Many, many species are out there but not yet scientifically discovered or described. Parasites range from simple, microscopic single-celled animals or protozoa, to multi-celled animals large enough to see, like fleas, ticks, lice, tapeworms and some other 'worms'. The designation 'worm' actually has no meaning in terms of classification … it merely denotes a rather lengthened invertebrate animal without limbs, and so it fits groups that are not at all closely related. Some big 'worm' groups include the Nematodes or Roundworms, Digenean trematodes, Monogeneans and Acanthocephala or Thorny-headed Worms, all of which include parasitic species.
At the University's parasitology lab, which you see here, students from South Africa work together with students from other countries like Zimbabwe, Namibia and the Democratic Republic of the Congo. Science today is a worldwide endeavour; many samples from this lab reach other labs even as far as Europe for extra investigation. Most of the work done here is about fish health and parasites.
There are several posters in the lab regarding fish, and the work being done on them. Here you see one. It is about pansteatitis in fish, a disease affecting the fat stored in a fish's body. The disease is caused or exacerbated by human-caused disturbances of natural freshwater ecosystems.
Aside from fish, the lab also does a lot of work with amphibians, reptiles, mammals and birds. With parasites, we get a spectrum of specialization. Some species parasitize a large variety of hosts, while other species are host-specific. On any individual animal, you might find some broad-scope parasites that also occur on many other species, as well as other parasites that only prey on that particular species or close relatives of it. With the incredible diversity of animals that live in South Africa, and given that any individual animal can have many parasites of many different species on it (ectoparasite) or in it (endoparasite), it is necessary to inspect as many different individuals of as many different species as possible. Now the lab manages to obtain a large variety of samples by collecting roadkill victims. Ali has mobilized a veritable army of people in our region into collecting any dead animals they find on or beside the road and send it to his lab. Here you see a freezer containing numerous such specimens.
It's not always possible to immediately analyse a specimen, so most of them stay in the freezers for quite a while. The lab of course prefers the animals as fresh as possible, as recently-dead as possible. As soon as decomposition sets in, it becomes tough to screen the tissues for parasites. When their hosts die, the parasites soon die as well, and decompose in their turn. Surface parasites like ticks and fleas will jump off a dead host and seek a fresh and new host to live one. But it is still possible to find some parasites or traces of them in fairly decomposed animals. Again, rather not a very glamorous task!
Here you see a specimen Michael, one of Dr. Ali's students, brought out of storage for me. This is a Giant Plated Lizard. The freezer it came from contains a large variety of snakes as well.
On the day, there were two fresh corpses ready to be dissected. Rather tragically, both were quite young animals. The small one on the left is a Banded Mongoose, Mungos mungo, while the larger one on the right is a White-tailed Mongoose, Ichneumia albicauda. Both were victims on roads in Venda. I only had time to stay around for the dissection of the little white-tailed mongoose. Its skull was crushed but its body mostly intact.
These things have to be done by protocol. Here you see the two forms needed to be filled in for the samples from each mongoose, the white-tailed on the left and the banded on the right. Samples are taken from the liver, spleen, muscles, lungs, kidneys and (unless too badly damaged – which in the case of our mongoose was sadly the case) the brain. Faecal samples may also be taken. Each sample is analysed for the particular kind/s of parasites likely to be found in it. The samples are stored in small, labelled specimen bottles which you see here with the forms.
Before cutting into the mongoose, Michael went through its fur with a fine comb as you see here. This is to pick up external parasites like lice, ticks and fleas. This one seems to have been quite clean, we just got a single tick. But it might be that most of its ticks and fleas and things jumped off it after it died. Michael also collected a sample of the fur itself, which will be analysed genetically. It's amazing how easy it is becoming to sequence the genes of just about anything. This helps us to understand genetic diversity, relationships and classification of critters.
The next photo shows the poor mongoose with (most of) its skin off. It was interesting to me to be able to see its muscles and bones and how they're arranged. It had very little subcutaneous fat. Its muscles were quite thin, some like the pectorals and latissimus being flat sheets. But it had thicker muscles on the thighs and upper arms.
Here you see the entire spleen of the mongoose, as well as a part of its diaphragm. The spleen is very long and rather flat. In cases of bad infection, the spleen enlarges. This one had a spleen of about 10 g in weight, which I think is rather large for the size of the animal (the mongoose was weighed and was about 1.4 kg). From the diaphragm, about 5 g needed to be taken as a specimen, to be analyzed for Trichinella (nematodes).
I photographed a petri dish with numerous samples on it, but the photo was out of focus. At any rate Michael took several samples and put each in a little sample bottle. The samples then are stored in a freezer prior to being investigated. Analysis is done with numerous techniques. Some parasites are visible to the naked eye, others are seen through light microscopes. Some tricks are used, such as treating muscle with pepsin, which digests the muscle tissue but leaves the parasite intact.
The skins and bones of some of the specimen animals can also be put to use. Here you see, in Ali's office, a collection of bird's feet, and a few bones, including a complete skeleton of a Ground Squirrel and the skull of a dog. There's also a little stuffed thick-tailed bushbaby in the office, This specific bushbaby was killed by a dog. Dogs are one of the threats to bushbabies in Limpopo. I must say, the living ones look much better.
There you have it. This is how science is actually done, in all its lack of glamour. But we need people who are up for doing this. And, I would say, there is satisfaction in the job itself also. It's cool to find something out which no-one knew before. It's good to know you're helping enlarge the pool of human knowledge, and doing work that may enable humans to understand their living environment better and to have a chance of living in harmony with it. We need to spread awareness of science, in all of its aspects. There is such an amount of work still to do.
For more information, collaborations or volunteering at the lab you may contact Dr Ali on email or whatsapp (in South Africa):
[email protected] 0027 718321739