xRapid – Thick Film Functionality: A Word from xRapid CTO Professor David Mendels

Thick film analysis for xRapid is now functional.

In its current form we have matched the accuracy of standard rapid diagnostic tests based on slides from the London School of Hygiene and Tropical Medicine. Like our thin film analysis, our diagnostic test based on a thick film slide is still a fraction of the cost of RDTs and provides a faster, cheaper and more accurate method of diagnosis than anything on the market.

The analysis of thick film slides using xRapid gives an accurate range of parasite count. The technology is able to tell if the patient has high, medium or low parasitaemia. Quantitative as well as qualitative diagnosis such as this is an important factor in why xRapid gives a superior diagnosis to other methods. Currently, our thick film analysis is unable to show the specific plasmodium species present in the blood, but our thin film analysis can achieve this to a very high level of accuracy.


A demonstration photograph from an xRapid thick film analysis: This photograph shows a positive result with a medium parasite count. As seen in the photograph, xRapid highlights the infected blood cells, differentiating them from the rest of the slide.



We have been working on introducing thick film analysis for a while but recent trials and conversations with potential users have shown that it is very much needed both in the field and in the laboratory. Our users in Uganda and Benin have effectively demanded it. The reasons are that  thick films are easier to prepare than the thin films, and the concentration of parasites is much higher thereby providing a lower limit of detection. The current method of staining a thick film slide is mainly easier because a user doesn’t have to carry two fluids. The minimum a user needs to treat a slide is purified water and giemsa. This simplifies the preparation as the third fluid for a thin film analysis – methanol – is not required.

However, the thick film does have its issues when compared to the thin film. There is often a degree of human error in preparing a thick film slide meaning that it is often not easily readable with the eye. This is why some people need a lot of training. Most of the training for diagnosing malaria should really be spent on how to prepare the slide rather than reading it because ensuring a high level of quality in how the slide is prepared is so vital for good results.

It is still important to note that preparing the thick film with three fluids is better practise than two. With the thin film you fix using methanol and the thick film needs the lysis of the red blood cells. At the Pitié-Salpétrèere Hospital in Paris a saponin solution is used for the lysis of red blood cells and platelets on a thick film slide, which produces  better results and despite the use of an extra fluid alongside purified water and giemsa stain, provides a much easier to read slide. The new xRapid thick film analysis enables to read slides whose preparation was beyond optimal.

Because of the complexities of slide preparation we will be shipping all units of xRapid with instructions for best practice in this area alongside our instructions for using the software and hardware.

What is it like to work at xRapid? An interview with medical intern Elena Bax.

At xRapid we value the contributions of our staff on every level. Our most recent intern, Elena Bax, performed key tasks for our research and worked closely with CTO and creator of xRapid Professor David Mendels. Upon completion of her 8 week placement, we spoke to Elena about her experiences on her internship.

Hello Elena. So lets begin with introductions, can you tell everyone a little about yourself?

I’m 19, I study medicine at University College London and for the past 8 weeks I have been working as a medical intern for xRapid, mainly at the London School of Hygiene and Tropical Medicine.

How did you find out about xRapid? What was the process for starting your internship?

I actually googled medical start-ups and xRapid was one of the first that came up. It was relatively easy to find the website and find out about the company, and from the contact page I emailed Jean and within a few days he replied and we organised to meet up.

I also had previously heard about xRapid through the Nominet Trust 100 list for social innovation, so when I found xRapid after looking for a healthcare internship on google the recognition was already there.

Can you explain what you have been working on over the course of the internship?

I’ve been primarily working with the xRapid app with David Mendels and using the repository of malaria slides at LSHTM to further improve parasite recognition. I have been mostly taking pictures of slides so that David can then run them through the app to test that it is picking up the malaria. The results have been very successful and it felt like we made a good degree of tangible progress as it resulted in several updates that only serve to improve the efficacy of the diagnostic test. The system works on a method of pattern recognition, so each photograph strengthens how effectively the app picks up the patterns within the red blood cells.

I have also been comparing these pictures to what I see myself under the microscope. It has been interesting to learn how to identify the malaria parasite and use this knowledge to check that xRapid is picking up the disease accurately.

What was the most interesting thing about the internship? Was there something that you learnt or a task that you had to perform that you particularly enjoyed?

Before the internship I hadn’t used a microscope that much, so it was really interesting to be in a proper laboratory setting for the first time, using the microscope and learning about malaria. Learning how to diagnose malaria was particularly interesting as its a skill I don’t think all that many people my age have!

What do you think the most exciting thing about xRapid is? Having used the technology in a clinical setting, can you see where it might help people both inside and outside of the laboratory?

Whats really good about xRapid is that it’s so small and can be taken anywhere, and that it requires very little training to use. What I found out with this internship was that it takes a lot of practice and training to get good at reading the slides and actually being confident enough to make a diagnosis. I also think it could be useful to attach the iPhone to a bigger microscope, just so that those that aren’t as confident with reading slides can use it for support or potentially rely on it completely.

Outside the laboratory I think there is a very interesting military application. When I was working at LSHTM there was someone in the same lab who was working on behalf of the German army and he was very interested in how xRapid could be used for them. I think this is because its so portable, and they spend so much money on heavy, expensive equipment.

What was your favorite thing about working for xRapid? Was there anything that stood out about the company that you thought was different from others?

It was really great to be part of a small start-up because you actually feel quite important within the company and you get a lot of responsibility. You feel like you are actually contributing to something, making it better and helping it grow as opposed to just grabbing coffees for someone or not really doing much. It was nice to feel quite important and included in everything that was going on.

I worked quite closely with David who is quite senior and is the mind behind the whole thing. It was interesting to witness how he thought about and rationalised everything and then also see how it all progressed. All in all it was a rewarding experience and I would recommend xRapid to anyone else who is looking for an internship in the health sector.




The World’s First Malaria Vaccine.

The worlds first malaria vaccine is facing WHO review, but how significant could it be in the fight against the disease, and where does diagnostic technology fit in?

« There’s a lot of excitement for a malaria vaccine. But it’s a very complicated vaccine, so the recommendation is presumably going to be complicated too. » – Seth Berkley, chief executive of the GAVI global vaccine group.

At last, a malaria vaccine has been given the go ahead by a regulatory agency and has taken a huge step towards global implementation. RTS, S, a vaccine with the product name « Mosquirix » has been under development led by GlaxoSmithKlein for years, and has finally come to a stage where it is nearing public release. The vaccine has been developed for babies and toddlers – a demographic wherein a large proportion of malaria deaths fall.

Vaccinations have been the literal lifesaver of hundreds of millions of people since the days of Louis Pasteur and Robert Koch. They have contributed to falling rates of terrible diseases such as measles, meningitis and tuberculosis and in some cases heavily contributed towards the eradication of deadly diseases such as smallpox. Put simply, if similar success could be demonstrated in a malaria vaccine, humanity will have made another astounding public health and economic breakthrough.

A malaria vaccine is a complex beast however. The parasite itself is large, complicated and adaptable and this is why developing an efficient vaccine has been an almost insurmountable challenge for researchers the world over. The malaria vaccine that has been recently produced has received positive scientific opinion from the European Medicines Agency but has been shown to provide only limited protection and efficacy.  A large scale clinical trial shows that the best results for children aged 5-17 months only provided 50% efficacy, with a lower figure for babies aged 6-12 weeks. Furthermore, the malaria vaccine was only fully effective with a course of four doses over 18 months, with dwindling protection from the disease after this period.

These figures make the future look a little less bright for Mosquirix, but despite criticism, there is still large potential for this vaccine to help millions of people. If a constant level of 30% efficacy can be achieved, which appears very likely, 30% of the babies and toddlers at risk of malaria worldwide could be protected. This could save tens, if not hundreds of thousands of lives.

‘Despite the falling efficacy over time, there is still a clear benefit; given that there were an estimated 198 million malaria cases in 2013, this level of efficacy potentially translates into millions of cases of malaria in children being prevented.’ – Brian Greenwood, professor of clinical tropical medicine at the London School of Hygiene & Tropical Medicine. 

Clearly, the further development and increased efficacy of malaria vaccines over time would be a significant breakthrough against malaria. It would help to reduce the economic and humanitarian cost drastically, and at xRapid we think there is a place for new diagnostic technology in making this happen.

With portable, accurate diagnostic tools that have the mobile capability to gather diagnostic data, store patient records and distribute valuable disease control information, the strength of a vaccine can be accurately tracked. One of the challenges for this new malaria vaccine is that due to it’s limited efficacy, it needs to be able to fit into current malaria management systems and work with the tools available.

« The challenges are around where this vaccine could provide additional benefits to the tools we already have. » – Pedro Alonso, director of the World Health Organization’s Global Malaria Program.

Parallel innovations in diagnostic technology are important in supporting the success of new treatments and vaccines for malaria. A diagnostic tool like xRapid that measures parasite count could be vital in measuring how well a vaccine is protecting its users, and the disease mapping potential of xRapid can pinpoint epidemics and communities that need to receive further protection from malaria, one possible implication being the use of a vaccine.

The further implications of a malaria vaccine remain unforeseen, but it is safe to say that everyone fighting against the disease from any angle within diagnostics, treatment, prevention and control should be excited by this breakthrough. The potential this vaccine has for protecting children is undeniable, and whilst we may not be able to reach the high standards of the smallpox or polio vaccines currently, it is a large stride towards protecting the children of the world from this deadly disease.

Our Technology: An interview with the inventor of xRapid; Professor David Mendels.

Welcome to another interview from xRapid.com. In this interview we speak to xRapid CTO and Co-founder, technology expert Professor David Mendels. This interview is an in depth explanation of the technical side of xRapid and the story of its development from the perspective of the person that created it. David gives some excellent insights into how the project came together and explains his vision for the use xRapid in the field.

« There is one malaria figure that has stayed with me ever since and that is the amount of children who die every minute; 1-1.5. It’s unfair. A single child dying of malaria which is a disease we know how to cure and how to eradicate is just not fair. »

Let’s start with talking a little about your background in technology and what your current role as CTO at xRapid involves.

I’m originally a material scientist, specialising in polymer physics. I then went into micro and nano technology. After a stint as an independent researcher working on contract and large project basis, I took a sabbatical for a year in Indonesia as my wife is originally from there. We decided to stay in Indonesia and I joined a new university as a professor which led me into developing large amounts of software, eventually leading to my work on xRapid.

What is the inspiration behind xRapid? When did you realise you were able to build it?

Innovation is a sum of small things. Many of these things can be serendipitous and the result of other outside factors can mean a final product is different to the one you started from scratch.  One thing that attracted me to joining the new university in Indonesia was that I could start working from scratch on new projects, but having no equipment was a restraint to what I was able to achieve. However, the two things that you can achieve in physics with very little equipment are modelling and programming, and I started out doing quite a lot of both. I produced two apps for the iPhone, one of which never got to the app store. However, this app was a suite of photo filters that eventually led me to the development of something with much larger potential.

xRapid came about because I had that suite of photo filters. I went to a presentation where someone showed slides of malaria with some infected blood cells with a nice staining and nice colouration; for people who may not be aware and may not know what this is, you just stain a thin smear blood slide and the red blood cells come out pinkish and the malaria and white blood cells come out dark blue. I thought; “I have a photo filter that can separate those colours, I should try it”. I went to purchase a $10 dollar plastic microscope attachment for the iPhone, put it on and realised it was working. I could see malaria on a blood slide almost without effort. From that point onwards I was convinced you could use the iPhone as a detector for malaria and possibly other diseases.

– Left: Professor Mendels works on an early version of xRapid, right: An early version of xRapid in Action.

What is the story so far at the company? xRapid was founded just over a year ago; how has it progressed in that time?

Between the first bit of code where you show it works and getting some code to production level is actually quite a lot of work. This has taken up most of my time over the past year. We signed up with Jean (Viry-Babel, CEO) to found xRapid 13 months ago and there was everything to build. Jean has been building the company side in London and I have been building the software side pretty much everywhere around the world.

It’s been really interesting to get the software to work better and to get the software to do what those in the eHealth domain want it to do. Things like the parasite count we didn’t plan in the beginning; for me the test was a yes or no answer. In terms of identifying the type of malaria, we didn’t realise we could do it in the beginning but we realised that we could do it, not easily, but we were able to make it work. So each of these tasks burns about 3-4 months of R&D. Assembling technology that is stable and reproduces the same results also takes a huge amount of time particularly without a standardised library of slides. To produce something like we have that fulfills our expectations to 90-100% hasn’t been easy, it’s got to be perfect.

Working with something biological you realise there is so many obstacles by nature, and sometimes you have to just face them head on, much like our intern Elena Bax is doing at the moment, the bulk of research she is undertaking is there to make sure we have completely consistent results in the field.


– A current version of xRapid

Can you explain to us how it works it simple terms? What does it do differently from traditional microscopy and modern rapid diagnostic tests?

The traditional test has always been the microscope. At the end of the nineteenth century the malaria parasite was discovered by a French doctor without staining technology. You could just see the parasite at its late stages; you could see the contours. After staining was discovered it has been easier to train microscopists to identify the disease and the parasite count.

The purpose of xRapid is to do exactly what the microscopist does and replace the microscopist so that there is little or no training needed, there is less error and you are able to read more slides per hour. One of the biggest problems with using a traditional microscope to detect malaria is that you need a lot of training to use it properly. Having done the training myself I think you need one week at least. I had been working on the software for a long time when I did my weeks training, I knew exactly what I was looking for, but I definitely still needed it. In the field when you are going to Africa or South East Asia most people would get about half a day of training when you really need an absolute minimum of two days before you can start performing accurate testing. Compare that with xRapid; you can train a person to use it in less than an hour and less than ten minutes if the slides are already prepared.

The technology works like the human eye; you are identifying different fields by their colours. Then we use a segmentation that is contouring red blood cells and white blood cells to identify them and then removing the background and the white blood cells to be left with only red blood cells. Within the red blood cells, when looking for malaria, we use segmentation and histograms to identify something you would not normally expect to find in a red blood cell. If you have identified something, you have to identify all of the information about the abnormality. We do this by employing a pattern recognition algorithm. The processor can deal with a large field of cells, so this calculation is happening several times simultaneously, and repeating this process across several fields gives a very clear picture of the parasite count of a patient. From that point the operator has a firm diagnosis.

There are various processes for treatment after diagnosis but roughly the most common, in the case of plasmodium falciparum, is that if you are below 2% parasite count you will be treated with a pill, and if you are above 2% you will be in a critical condition and will have to be hospitalised so the parasite count could save your life.

xRapid is an innovation that’s built to help people – where do you think it can have the biggest impact?

When we were pitching xRapid to investors with Jean, he came up with the malaria numbers. There is one that has stayed with me ever since and that is the amount of children who die every minute; 1-1.5. It’s unfair. A single child dying of malaria which is a disease we know how to cure and how to eradicate is just not fair. It’s a disease of the poor so in poor countries where people don’t have a proper sanitation system it is a real struggle. This is because a proper sanitation system can not only provide clean water and waste management but also the ability to eradicate flocks of mosquitos.

The two ideas behind the xRapid technology are that for the first time we have a high powered computer in your pocket, developers keep telling us this but as of yet nobody is doing anything with that power in terms of serious software that achieves something other than just distracting you. All that beautiful power is used for Facebook, Twitter and the like.

The second idea is that you have something in your pocket with two cameras and GPS recognition that is constantly connected with the internet. You can do an awful lot of things with this. As an engineer I found GPS really interesting. What if instead of just doing standard biology analysis we could provide a large number of devices providing large amounts of data? From there we would have a great platform to help provide proper disease control. Say there is a province in Indonesia where there is 500 dispensaries for malaria eradication. If we have an xRapid in each of these dispensaries we can map the full population of that province in real time. If we see that we have a spike of cases in my map, relevant control measures could be deployed, the area can be sprayed and the eggs can be killed.

The main problem with mosquito controls is that the mosquito passes malaria to humans, other mosquitos contract the parasite from the infected human blood and they, in turn, pass it to the cattle. Once the malaria is in the cattle it won’t go away, so if we can catch the parasite before it reaches them through mapping we have a good chance of getting rid of malaria from entire regions.

What does the future hold for the technology? Are there are other things in development further down the road that you can discuss?

As we are putting the first generation of new devices out we are already working on the second generation and the second generation is very promising, but that’s all that I can say about that for now.

Apart from that, we are really excited to see xRapid perform in the field. If you browse our website you can see that we have been working on the thin smear for the longest amount of time, but we have another solution coming up with the thick smear. This makes preparing slides slightly easier and makes low parasite count identification easier. It does make identifying the species more difficult but countries that have requested thick smear method do not see this as relevant as they are exclusively concerned with plasmodium falciparum. For these countries this method improves the speed of the process drastically. Within the next few days this method is going to be tested in the field.