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Super-flies and parasites

Yellow fever mosquito.

Nature isn't always nice. Scientists in the Museum's Parasites and Vectors Division are studying species of insect and worm that live on or inside animals, including humans, acting as tiny agents of disease.

Our huge parasite and insect collections help us to understand how these organisms evolve, how they spread disease and how we can control them. Read on to hear about our fieldwork, research techniques and special projects.

Parasites and vectors research at the Museum

The schistosomiasis collection

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Hello Super-flies and Parasites fans!

 

We are back with all things nasty from the Parasites and Vectors division here at the Museum. There have been some exciting developments in the New Year, most importantly the launch of the Museum’s brand new website!

 

This is another ‘Forever Flies’ series of blog posts, bringing you news from the Museum'sforensic entomologygroup.

green-bottle fly.jpg

Forever Flies is our forensic entomology blog series. This image shows a carrion-eating greenbottle blowfly.

 


Forensic Entomology

You will remember from my previous Forever Flies post that forensic entomology is the study of the insects and arthropods found at a crime scene. The most common role for Museum forensic entomologists is establishing a minimum time since death in suspicious cases, by analysing the carrion insects on the body.

 

2014-10-16 Gross maggots with adult.jpg   issue2forensic3_large.jpg

Blowflies use the bodies of dead animals to grow and develop. The rate at which they do this, going from egg to larva to pupa to adult fly, is pretty consistent and depends largely on ambient temperature. Forensic entomologists use this to determine the minimum post-mortem interval (PMImin), which helps crime scene investigators determine approximate time-of-death.


Thanks to entomological expertise (Greek – entomo = insect, logos = knowledge) scientists can collect insects from a corpse and/or crime scene, determine what stage in their life cycle the insects have reached and, using their knowledge on the duration of each stage of the insects’ life cycle, determine how long ago the parent insect laid her eggs on the corpse.

 

This gives an incredibly useful estimate of the minimum amount of time this body has been dead (minimum post-mortem interval - PMImin), which helps crime scene investigators determine approximate time-of-death. The more accurate this minimum post-mortem interval is, the more accurate the time of death can be. Knowing time of death can focus the police investigation and suggest the likelihood of a suspect’s involvement.

 

Scientists can also use these insects to determine if the body has been moved since death and how long a body was exposed above ground before burial.

 

Metamorphosis in pupae


Flies spend over 50% of their developmental life in the pupae stage, protectively encased inside a hard shell (called a puparium) where they slowly transform from a maggot into a fly in a process called metamorphosis (Greek again - Meta = change, morphe = form).

 

A puparium looks quite bland and boring but underneath there are all sorts of wonderful things going on. Scientists can remove the shell and, using traditional microscopy, take a look at the fascinating changes of metamorphosis. But this process does destroy the pupa sample, making it difficult to work out how long it takes for the pupa to go through the different stages of metamorphosis.

 

Scientists know that the length of time metamorphosis takes to complete really depends on temperature, the question is can we use our knowledge of the process to pinpoint a more accurate estimate of PMImin?  What forensic scientists need is a standardised method to work out:

  1. At what stage in the metamorphosis process is the pupa
  2. how long did it take to reach this stage

 

If these two points can be determined then scientists can provide a far more accurate PMImin.

 

The ‘MORPHIC’ project

 

Dr Daniel Martin-Vega, a forensic entomologist, has joined the Museum from the University of Alcalá in Spain to research carrion fly pupae and to develop a standardised protocol for aging pupae (as in determining their age) that can be used by forensic scientists. This project is called MORPHIC and is funded by the European Commission through a Marie-Curie fellowship.

 

It sounds all neat, logical and tidy but there is A LOT of work and dedication involved!

 

For this projectDaniel is raising two species of the carrion-loving blowflies, the greenbottle blowfly Lucilia sericata and the bluebottle blowfly Calliphora vicina. The flies live in netting covered cages, where they feed and reproduce whilst he monitors them.

 

Daniel feeding flies_resized2.jpgDaniel showing me the Diptera (insect) culture room. Each netting-covered box has a species of carrion blowfly in it. He is researching the pupae of these flies to see if he can improve the estimate of  PMImin and thus improve the information given to crime scene investigators.


He also has to collect the post-feeding maggots and place them in a box with some nice clean soil for them to happily grow until they are ready to start the metamorphosis process. These boxes are then placed in a cabinet kept at a specific temperature. Since the rate of metamorphosis largely depends on temperature it is very important the Daniel can control this environmental factor in order to document the rate of change at different temperatures.

 

where do you keep the maggots_resized2.jpg

The maggot house! This is a comfy box with soil where maggots crawl around and prepare to pupate. When the maggots start pupating Daniel has to come in every 6 hours or so to monitor and collect them for his research

 

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Blowfly maggots and pupae.

 

 

Once the maggots start to pupate Daniel has to collect the pupae:

 

I come in every 6 hours when the maggots start to pupariate in order to collect blowfly pupae at 6-hour intervals during the first 48 hours after puparium formation (the period when the greatest morphological changes of metamorphosis occur). Luckily, I only do this from time to time. After that, the collection of pupae is just daily until the adult flies’ emergence.

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Daniel sieving out the pupae from the box.

 

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Maggots and pupae, oh my!

 

Watch those maggots wriggle about!

 

He then has to sieve out the pupae from the soil and carefully place them in a petridish labelled with the blowfly species name, the date collected and the time collected. These petridishes are also placed in the special temperature-control cabinet.

 

 

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Daniel has separated out the pupae of different species of blowfly. Each petridish with pupae has the species name, the date collected and the time collected.

 

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The petridishes are kept at a specific temperature. Since the rate of metamorphosis largely depends on temperature it is very important the Daniel can control this environmental factor.

 

Daniel uses the Museum’s wonderful micro-computed tomography (micro-CT) scanner to take detailed images of the inside of the pupae without destroying them. A micro-CT scanner is a type of X-ray scanner that produces 3D images, much like a hospital CAT scanner, but at a much smaller scale and a higher resolution. The results are like 3D microscope images! 

 

Thomas Simonsen and Daniel Martin-Vega analysing CT images of 5 pupae.jpg Thomas Simonsen and Daniel Martin-Vega operating Micro-CT scanner.jpg

Daniel with colleague Dr Thomas Simonsen using the Museum’s micro-CT scanner to look at 3D images of blow-fly pupae. The micro-CT scanner uses x-ray technology to produce 3D 'microscopy' images at high resolution without damaging the sample.

 

By using the Museum’s micro-CT scanner Daniel can take these detailed images at specific time points of the metamorphosis process.  He will then have a catalogue of images of the blow fly pupal development at specific temperatures. This catalogue of images will be used to develop a standardised tool to determine the age of blow fly pupae. Then when pupae are collected from a crime scene, they can be compared to this catalogue and scientists will be able to determine how long the fly has been in its pupal stage. Giving scientists a more accurate estimate of PMImin! Ta daaaaa!

 

C_vicina-48h.jpgC_vicina-216h.jpg

Micro-CT scanner images of a bluebottle blowfly Calliphora vicina pupa. The one on the left is at 48 hours, the one on the right at 216 hours. You can see the difference in development between the two pupa images.

 

Micro-CT scan of blowfly pupa.jpg

Dorsal micro-CT scanner image of a blowfly pupa.

 

I hope you enjoyed this post. If you fancy a stab at a bit of CSI work why not check out the Museum's Crime Scene Live After Hours events.

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Hello Super-flies & Parasites fans!

 

This time we are departing from the familiar world of blood flukes and having a look at something new and exciting: Welcome to the ‘Forever Flies’series of blog posts. I’ve really enjoyed writing this bit as it’s totally new to me and I’m learning so much from our wonderful scientists in the Forensic Entomology group of the Parasites & Vectors division here at the Museum.

 

About forensic entomology


I think I mentioned forensic entomology way back in the first ever Super-flies and Parasites post. But to refresh our memories and delve a bit deeper here’s an explanation taken from the group’s website:

'Forensic entomology is the study of insects and other arthropods (ie spiders, mites) in a situation where a crime may have been committed. The insects recovered from a crime scene can provide vital information for the investigating team. The most common role for Museum forensic entomologists is establishing a minimum time since death in suspicious cases, by analysing the carrion insects on the body.'

 

Flies use the bodies of dead animals to grow and develop, fulfilling a vital nutrient recycling role in an ecosystem. They can turn one vertebrate body into thousands or millions of flies, which are then fed on by other animals - insects, frogs and birds for example. The rate at which they do this, going from eggs to larvae to pupa to adult fly, is pretty consistent.

 

Knowing enough about the species of flies we can exploit this information when they develop on corpses. By determining how long the insects have been feeding on the tissues of the corpse, we can determine the length of time elapsed since flies found the body; thereby providing crime scene investigators with a minimum post-mortem interval.

 

Some flies however don’t hang about and wait for death, they prefer feeding on live animal tissues, and can cause a horrible disease called myiasis, a major economic and animal welfare problem.


2014-10-16 Gross maggots with adult.jpg

Female Bluebottle blow fly, Calliphora vicina, and maggots feeding on a dead pig.

 

Dr Martin Hall and colleagues within the Museum and around the world work together on the taxonomy and biology of flies that develop as larvae on living or dead vertebrate animals. Their expertise and research greatly contributes to the control of a painful and damaging disease, myiasis, but also to the field of forensic entomology, helping CSIs determine crucial information from a crime scene.

 

So there you have it, some real life crime scene investigation stuff! These are the guys CSIs turn to for help! (Cue CSI theme song!)

 

The beauty of maggots lies in their mouthparts

 

I asked Martin for a little blurb to get the Forever Flies series rolling and he sent me some surprisingly beautiful photos of maggots! Here’s what he has to say about them:

To most people maggots are repulsive creatures; they all look much the same and have zero redeeming features.

 

2014-10-16 Gross maggots 1-1.jpg2014-10-16 Gross maggots 2.jpg

Maggots, thought of as repulsive creatures with zero redeeming features. Read on to see how they are transformed by confocal microscopy into beautiful works of art.


However, viewed under a microscope they become much more interesting, with a range of characters that can be used in discrimination, especially when you look at the business end of the maggot, its mouthparts!

 

It’s not so easy to ask a tiny 2mm long newly hatched maggot to 'open wide' to view the teeth, and traditionally we have been limited to viewing slide-mounted specimens by light microscopy. Scanning electron microscopy has its merits, but only for the external features. In normal light microscopy, imaging of these mouthpart structures is limited by problems of resolution, illumination and depth of field.


Lucilia sericata L1 - Light microscope high power.jpg

Greenbottle blowfly, Lucilia sericata light microscope high power image. With normal light microscopy the relationship of the sclerites of the cephaloskeleton (mouthparts) to each other is unclear.

 

At the Museum we have been using a laser confocal microscope for the first time to look inside these maggots to view the mouthparts, the so-called cephaloskeleton, in three dimensions. The mouthparts are crucial to the maggots in establishing themselves on their food source, be it a live animal or a decomposing corpse. The images produced by the confocal microscope rely on the autofluorescence of structures of the cephaloskeleton.


Lucilia sericata LI - Confocal microscope low power.jpg

Greenbottle blowfly, Lucilia sericata confocal microscope low power image - relationships are still unclear but, with the autofluorescence under laser light, the structures look so much more beautiful!

 

We were especially interested in the relationships of the small sclerites to each other and the so called 'hump', present in newly hatched larvae of Lucilia greenbottle blowflies but absent in Calliphora bluebottles.


Lucilia sericata L1 - Confocal microscope high powerWITH ARROW.jpg

Greenbottle blowfly, Lucilia sericata confocal microscope high power image: The structure relationships are becoming clearer (the 'hump' is arrowed) and this is finalised in the next image.

 

The 177 optical sections scanned by the confocal microscope enabled us to rotate and view this structure in three dimensions (see green false-coloured sclerite in image below) and see clearly for the first time how it relates to other structures.

 

In addition to their academic and practical value in identification, the images are also things of beauty in their own right and would not look out of place in an art gallery!


Lucilia sericata - Confocal high power - false colour sclerites named.jpg

Greenbottle blowfly, Lucilia sericata confocal microscope high power image and false colour sclerites. We have rotated the original to give three dimensionality. The red wavelength was selected, as this is the wavelength that gave most autofluorescence of the cephaloskeleton, to enable us to discard other structures and here false-colour has been added to show the different structures, including the 'hump' (in green) or epistomal sclerite.

 

The work was done at the Museum and involved Drs Andrzej Grzywacz (a visitor under the EC-funded SYNTHESIS project) and Krzysztof Szpila from the Nicolaus Copernicus University in ToruĊ„, Poland, collaborating with Tomasz Góral and Martin Hall. We used the Museum’s Nikon A1-Si Confocal Microscope.

 

For more information see the article published online in Parasitology Research on 19 September 2014.


By Dr Martin Hall

 

I hope you enjoyed the first 'Forever Flies' post. For more on flies head over to Erica McAlister's Diptera blog.

 

There will be more coming soon but just to let you know there may be a couple of weeks break whilst some important maintenance work is done to the site and my life

 

See you soon

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Hello blood fluke enthusiasts,

 

Once again I am posting about my favourite parasite, the blood fluke called Schistosoma. I want to tell you about an exciting project that is going on on the beautiful archipelago of Zanzibar.

 

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Zanzibar is a semi-autonomous archipelago of Tanzania. The two main islands are called Unguja (or Zanzibar island) and Pemba. We are working on a very exciting project to stop schistosomiasis transmission on these islands.

 

This is a bit of a long post but please if you can bear it read on! If successful this project could revolutionize our approach to schistosomiasis (blood fluke disease) control.

 

Schistosomiasis control

 

As I explained in my first blood fluke post, infection with the blood fluke Schistosoma causes a disease called Schistosomiasis (aka Bilharzia).

This disease affects over 200 million people worldwide, the majority living in sub-Saharan Africa. It is strongly linked to poverty and does heart-breaking damage to children and adults in the poorest and most vulnerable communities.

 

bloody urines.jpgSchistosomiasis-boy.jpg

The clinical symptoms of schistosomiasis aka bilharzia, the blood fluke disease: (L)  bloody urine from children excreting the parasite eggs through urination and (R) a malnourished child with a hugely enlarged liver due to damage caused by the parasite eggs stuck in the tissue.

 

Depending on the species of the infecting schistosome worms the disease can cause:

•          Diarrhoea, bloody stool, blood in urine, painful urination.

•          Anaemia, stunted growth, enlarged liver and spleen.

•          Damage to the liver leading to liver fibrosis.

•          Damage to the genitals, kidneys and bladder potentially leading to bladder cancer.

•          Increased risk to sexually transmitted diseases like HIV.

 

Currently there is no vaccine. Schistosomes are masters of disguise when it comes to the immune system which means vaccines that rely on your immune system are difficult to develop. Researchers are trying though! Thankfully there is an effective oral drug called Praziquantel that kills the adult worms in humans. BUT it is the only effective drug against all species of this parasite, which raises concerns regarding drug resistance, and it does not stop people from becoming re-infected.

 

school children in East Africa being treated with Praziquantel the only drug effective against all schistosome blood flukes.jpg

A boy being treated for schistosomiasis. The treatment is an oral dose of Praziquantel. Although the side-effects are minimal the pill is quite bitter and can cause stomach upsets so making sure a child has some yummy juice and a bit of food with treatment is important.

 

Up until now efforts to control schistosomiasis in sub-Saharan Africa have focused on regular treatment of school children to reduce infections and prevent the severity of the disease. The theory being that if you treat regularly you can prevent the child from developing those nasty outcomes listed above. The drug is donated and there are excellent NGOs providing support to programmes wishing to deliver the drugs to schools. Hurrah!

 

However this regular treatment approach has NOT interrupted schistosomiasis transmission in a sub-Saharan African country. This means it requires a (very) long term commitment from the programmes and ministries of health. A lot of these countries have weak and struggling health systems burdened with many challenges (lack of water & electricity, clean needles & surgical equipment, painkillers, antiseptic cream etc) as well as a whole range of poverty-loving diseases to deal with. How long can a struggling health system keep up 'regular' treatments in difficult to reach areas? Once these are missed, or the programme is interrupted, the disease comes back.

 

What about stopping transmission?

 

Elimination = stopping local transmission

 

This is is exactly what is being attempted in Zanzibar through a multi-institute and major collaborative project led by:

 

There are three additional key players:

  • My friend and colleague Dr Steffi Knopp from the Museum and the Swiss Tropical and Public Health Institute. Steffi is tirelessly overseeing the details and daily running of this project as well as analysing the results and publishing whatever new insight we get into schistosomiasis elimination from this ambitious project.
  • SCORE (Schistosomiasis Consortium for Operational Research and Evaluation) funds this project with money from the Bill and Melinda Gates Foundation.
  • Schistosomiasis Control Initiative, a wonderful NGO based at Imperial College providing countries with all the logistical and implementation support needed for national treatment programmes (they do accept donations and fundraising so if interested just get in touch.

 

Together (and with a few other people whom I have not mentioned and I do hope will forgive me), they form (drum roll please...):

 

ZEST – the Zanzibar Elimination of Schistosomiasis Transmission

 

(And now superhero music, or better yet Vangelis’ Chariots of Fire)

 

This project aims to answer the question:

What tools do we have to stop transmission and what is the most effective way of achieving this?

 

Schistosomiasis life cycle.jpg

Transmission between humans and snails occurs in the local water bodies. In order to reach the water the parasite eggs come out with stool or urine. Because there are rarely toilets and no sewage system or human waste treatment facilities this human waste reaches the water that people frequent and the snails live in. The parasite is then able to continue its life cycle by first infecting a snail and then infecting a human.

 

So where on the life cycle can we intervene to stop transmission?

  1. We can kill the adult worms inside people by treating them with Praziquantel – Mass Drug Administration to communities at risk of infection.
  2. We can remove the intermediate host snail from the human water contact areas – Snail Control in local water contact sites.
  3. We can stop the eggs from reaching the water and warn people from going into known transmission sites – Behavioural Change Intervention.

 

West Africa schistosome transmission site and local water collection point.jpg

A typical transmission site for schistosomiasis. Families come to the water to wash, clean, fish, etc.

 

These are the three interventions we have available to us. What is the most effective way to eliminate schistosomiasis in an area?

 

In order to test this ZEST has randomly organised all the distinct community areas of Zanzibar and Pemba into our three intervention groups:

 

Praziqauntel for ZEST.jpg

A car full of donated Praziquantel treatment for schistosomiasis, about to head out to the communities.

 

tested for schisto Pemba.jpg

Collecting urine samples from children to test for the presence of schistosoma eggs. This is how we diagnose schistososmiasis.

 

Snail control.jpg

Spraying local water contact sites with a chemical that kills the aquatic snail host of schistosomes.


Snail collecting Fiona.jpg

This is a familiar face to you I’m sure, Dr Fiona Allan our resident schistosome snail expert surveying sites in Zanzibar. She has a sixth sense on where the snails will be and where transmission occurs. We are now calling her 'snail whisperer'.

 

1. Mass Drug Administration – Treatment of communities twice a year with Praziquantel. Now the truth is it would be unethical not to treat people we know to be suffering from the disease purely in the name of science. We may be scientists but we’re not evil scientists! So EVERYONE on BOTH ISLANDS IS GETTING TREATMENT. But in group 1 they are ONLY receiving treatment. No snail control, no behavioural intervention. This is to test the effectiveness of the current approach (treating people regularly).

 

2. Snail Control - Snail Control by spraying transmission sites with a safe and gentle dose of Niclosamide. The communities are receiving treatment as normal however their villages have been surveyed for human-snail water contact and schistosomaisis transmission sites. These sites then get sprayed with the molluscicide (chemical that kills snails) Niclosamide. Niclosamide is also used as parasite treatment for livestock and is safe for mammals and birds. It does kill all snails though so we only want to use it in the areas that have transmission, nowhere else. We also know that it quickly breaksdown in the environment. This is good because it means it does not linger around however it’s also bad because a good rain storm and off it goes down the river without killing any schistosome infected snails.

 

3. Behavioural Change Intervention – Mobilizing communities by teaching them about schistosomiasis transmission and supporting them to find their own solutions. Education teams go out to the communities, teach the village leaders, the religious leaders, the teachers about schistosomaisis and the blood fluke life cycle. They then help the communities to develop ways of raising awareness of schistosomiasis, educating parents and children and encouraging positive behaviour change that will prevent disease transmission. This has taken form of:

    • Special Kichocho (Swahili word for schistosomiasis) events, where safe games are played, little educational sketches are watched and fun is had.
    • Training teachers to teach children at schools about the schistosoma life cycle.
    • Building latrines and urinals for children and adults to use instead of urinating outside.
    • Making signs warning people of the presence of kichocho in the water and the risk of infection.
    • Other solutions like safe clothes washing areas etc.

 

Kichocho_transmission_signs.jpg

Big red signs warning the community about the presence of Kichocho (schistosomes) and konokono (snails - intermediate hosts of schistosomes) in the local water.

 

The behavioural intervention team on Pemba and Michael, an MSc student from the University of Tulane, with the help of the wonderful behaviour scientist Dr Bobbie Person, have created an amazing educational video in Kiswahili to show in villages and schools. Do take a look - it is fantastic!

 

 

A video made by the schistosomiasis behaviour intervention team on Pemba with the help of Michael Celone to teach communities about the life cycle of Kichocho (schistosomiasis). The video is in Kiswahili with English subtitles.


 

 

A second video teaching communities about behaviours that increase transmission and risk of infection as well as what they can do to prevent Kichocho (schistosomiasis). The video is in Kiswahili with English subtitles.

 

ZEST.jpg

The Zanzibar Elimination of Schistosomiasis Transmission study design. MDA – Mass drug administration of safe anti-schistosomal drug Praziquantel delivered to the villagers twice a year. Snail Control – removing snails in human water contact sites by spraying with safe molluscicide Niclosamide. Behaviour Intervention – Community-lead behavioural change intervention to stop behaviour that leads to transmission/infection of schistosomes.

 

Wish us luck and watch this space!

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Come talk to me at Science Uncovered, a free evening of science-based fun and frolics this Friday 26 September! 

 

SU2014_SK_einvite.jpgScience Uncovered is a free evening event at the Museum. Come talk to me and other scientists about research, play games, ask some questions, have a few drinks and lots of fun!

 

At last year's Science Uncovered we had just under ten thousand people visiting the Museum in South Kensington and Tring and we hope to have just as good a turn out this year.

 

On the night there will be three main zones at the Museum:

  1. Origins and Evolution
  2. Biodiversity
  3. Sustainabilty

 

Each zone will have a range of science stations and activites related to the zone's theme. I will be at the Parasites and Pests station in the sustainability zone (which I am delighted to inform you is ideally placed near the cocktail bar!). Do come talk to me. We will have some great stuff for you to look at, including:

  • Live (uninfected) aquatic snails.
  • Portable microscope with samples of the schistosome blood fluke and eggs to look at.
  • Pickled schistosome worms preserved in ethanol (not for consumption just to look at).
  • Fieldwork equipment including the kit used to look for schistosome eggs, to filter eggs and collect the larval stage for DNA work and snail collecting material.
  • Games: Schistosome life cycle jigsaw puzzles.
  • Food: glittery parasite-shaped chocolates for consumption at your own risk (no parasites within, they are just shaped like parasites. Please note I make these myself so they may include nuts and other allergens).

 

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Come see schistosome eggs under the microscope.

 

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Take a look at our friendly live aquatic worms.

 

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Do you dare to sample my homemade parasite-shaped chocolates? They're getting their edible glitter suits on for this special occasion.

 

But this is just at our blood fluke station, I have heard exciting things about what others have planned for their stations, including bringing out shark samples and live animals, creating your own earthquake and of course the recently discovered Dr Livingstone's Beetle collection (covered by the press in this article) and much, much more. For more information on what's going on have a look at the Science Uncovered webpage.

 

What is Science Uncovered?

 

At Science Uncovered researchers showcase their research in engaging, interestings ways and chat with people about what they do, why they do it and why it's fun/important/interesting.

 

Science Uncovered is part of the European Researchers Night, funded by the European Commision. Events are taking place on Friday 26 September in about 200 cities across 43 countries.

 

The main outcomes we are aiming for are:

  • to raise awareness of the key role of research in soceity
  • to raise awareness of the wide diversity of people working in research
  • to give an understanding of the diverse range of research careers
  • to inspire the public to take part in other science activities
  • to encourage young people/students and their parents to consider careers in science

 

So when you come to the event and you're walking around the Museum looking at all the exciting activities, discoveries and discussions, do ask scientists a bit about their background, how they got into science, why they enjoy it, and anything else that takes your fancy. We are all wearing badges saying "I'm a scientist, talk to me". Please do not feel shy.

 

I hope to see you there!

1

Hello honorary parasitologists,

 

I know there has been a bit of radio silence on my part and I apologise, summer was calling me and there was a lot of stuff to get through before I could escape on annual leave.

 

I'm back now and picking up where we left off. Perhaps you are wondering what happened to all those samples we collected in Tanzania in May (see previous posts). Well wonder no longer, I am about to reveal all.

 

A quick recap of our collecting in Tanzania:

  1. We collected miracidia, the parasite larval stage from infected children, and stored them onto special paper (called Whatman® FTA cards) that stores their genetic material.
  2. We also collected the intermediate host snail from potential transmission sites on the banks of Lake Victoria.
  3. Finally we collected cercariae, the larval stage from infected snails, and stored their genetic material on the Whatman® FTA paper.

 

Visiting+schools+to+collect+schistosomes700.jpg

Visiting schools to identify infected children, collect the schistosome larval stage (miracidia) and treat the children.

 

Collecting snails in Tanzania.jpg

Snail collecting on the banks of Lake Victoria.

 

Schistosoma mansoni cercaraie&Biomphalaria sudanica.jpg

Collecting cercariae, the Schistosoma larval stage, from infected snails.

 

Whatman FTA and punch.jpg

Whatman® FTA cards store the genetic material of schistosome larvae collected from infected children and/or snails.


 

Storing our collected schistosome larvae on Whatman® FTA cards is ideal for us because:

  1. We avoid storing them in flammable liquids like ethanol.
  2. We avoid having to bring back live, infected snails.

 

...two things that aiports and customs really don't like!

 

The Whatman® FTA cards lyse (break) open the parasite cells and lock the genetic material onto the card, keeping it stable and safe at room temperature until we need to use it. So this means we can bring back our samples safely in our suitcases. Hurrah!

 

The snails, on the other hand, have to be stored in glass tubes with ethanol, so these we have to leave behind in the safe hands of the National Institute for Medical Research, Mwanza. Our collaborators take good care of them until we can arrange a courier service to bring them to the Museum.

 

SCAN_FTA card storage closeup.jpg

Whatman® FTA cards with collected schistosome genetic material from Tanzania, catalogued and stored safely by SCAN in the Molecular Collections Facility at the Museum.

 

Once back in the UK I hand over all collected samples and forms to the wonderful SCAN,Schistosomiasis Collection at the Natural History Museum, team. SCAN takes care of the thousands of schistosome samples collected from all over the world and stored at the Museum. This colleciton is very precious and in high demand for lab-based scienists researching the genome of the parasite and host snail in search of new ways to understand and control the disease. 

 

SCAN cares for collected samples and manages all the associated data, such as:

  • GPS coordinates - so we know where the sample has come from.
  • Collection method - what technique was used to collect the sample?
  • Date of collection - how old is the sample?
  • Storage medium -  is the sample stored on Whatman FTA card or ethanol or any other storage tool?
  • Data on the parasite host - did the sample come from an infected human, cattle, snail? If a snail what species? If a human what age? Gender? 

And lots more.

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The fieldwork forms I fill in when collecting samples in Tanzania. I hand these forms over to the SCAN team along with all my collected samples. They then have the frustrating task of trying to decipher my handwriting.

 

You have met two members of the SCAN team in my previous posts; Fiona Allan, who acted as our fieldwork photographer whilst helping me in Tanzania and Muriel Rabone, who came to my rescue after Fiona had to head back to the UK. There is just one more person for you to meet; the ever-patient and resourceful Aidan Emery, who manages SCAN

 

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Fiona and I going through my fieldwork forms and samples - "what have you written here? It's illegible!" Oops!

 

As you can see there is A LOT of data that goes with each and every schistosome/snail collected and researchers need to have all this information when analyising a parasite or snail sample. SCAN ensures that all this information is properly entered into a database and linked with the samples stored in the Molecular Collection Facility (more on this in a bit).

 

The SCAN team has even created a wonderful online catalogue of all the collected samples they care for, along with all the data linked to each sample. This greatly assists researchers from all over the world, allowing them to have a look and see what samples are available to them. 

 

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Fiona and Aidan storing the Tanzanian schistosome samples collected onto Whatman® FTA cards. Fiona is showing off the little blue booties we have to wear in the Molecular Collections Facility to avoid bringing in contaminants or anything that could harm the hundreds of thousands of precious samples stored there. 

 

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The SCAN team takes a photo and measures the size of every snail that arrives from our African collaborators. In order to extract the DNA from the snail for molecular work the shell must be crushed and removed. It is good to have a picture of what the shell looked like before doing so.

 

The Molecular Collections Facility is a crucial facility in the Museum, as it has all the equipment necessary to keep molecular and genetic samples (such as our schistosome samples) stored safely, stabily and for a long, long time. What equipment am I talking about? I mean: -80 freezers, nitrogen tanks, air-tight cabinets, equipment to release/elute genetic material from stored samples, centrifuges, pipetting robots, you name it. It is run by the very helpful Jackie Mackenzie-Dodds.

 

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Jackie runs the Molecular Collections Facility where all our schistosome samples are stored. All the freezers and nitrogen tanks have alarms linked to them to make sure they continue to function correctly. If one fails an alarm goes off on Jackie's mobile phone so no matter where she is she is immediately notified and able to respond.

 

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Jackie is showing me the liquid nitrogen tanks in the Molecular Collections Facility. Whilst nitrogen in gas form is harmless, liquid nitrogen is very, very cold and any contact with it can cause severe frostbite, even freeze your arm off. Also as it boils it uses up a lot of oxygen in the air, which can lead to asphyxiation. So oxygen monitors are always used. Its incredible freezing ability means it is very effective at storing rare, degraded and old tissue samples.

 

So there you have it, all our samples are archived carefully until we are able to perform the molecular work we need to do for species identification and to determine how the genetic diversity of the parasites is being affected by treatment control programs. My next couple of blood fluke posts will be about the techniques we use to do this. So read up on Polymerase Chain Reactions (PCR)... it does feature!

 

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Fiona and I have managed to decipher my handwriting! Hurrah! The samples are saved!

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About the author

Dr Anouk Gouvras.

Dr Anouk Gouvras is a researcher in the Parasites and Vectors Division of the Department of Life Sciences.

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