Icipe scientists isolate a Microsporidian capable of impairing Plasmodium transmission in Anopheles arabiensis
A team of scientists icipe together with their collaborators in the UK recently isolated and described a microbe, a Microsporidian, with the potential to impair transmission of Plasmodium falciparum parasites in species of Anopheles arabiensis, an important milestone in the fight against malaria. PAMCA interviewed the lead researcher, Dr Jeremy Herren to find out more about this significant development and his views about what should be done to strengthen the malaria response in Africa.
Dr Jeremy Herren is a Research Scientist at the icipe. He has nearly 20 years of experience working in the field of vector-borne disease control, notably malaria, focusing on insect host microbial symbiont interactions. He recently led a team of researchers working on mosquito-microbial symbiont interactions which culminated in the isolation of a bacterial (Microsporidia MB) shown to be capable of stopping malaria transmission.
Could you briefly tell us what type of research is done at icipe?
icipe is an international research institute that focuses on insect research. It’s in some way quite specific but also diverse. Any insect related research can be done at the institute, that involves a lot of agricultural pest research, research on beneficial insects including honeybee and silkworms, and also research on disease vectors. That is the area which I am specialising in and we study a number of disease vectors, but I am especially focused on the biology of malaria vectors.
Can you tell us a bit about yourself and the focus of your current research?
Originally my father is Swiss and my mother is American. They were both scientists much like I am, and they worked in Kenya. I grew up in Nairobi, I went to school here and decided to follow in their footsteps and be a scientist. My interest has always been in insect-microbe interactions and particularly the concept of symbiosis, something that I always found very fascinating. There is something about two organisms living and even working together that I find super interesting. Insects are especially commonly symbiotic partners. You get a lot of insects that rely on microbes for many aspects of their lives. Insect symbiosis is something which I specialized in quite earlier on and ultimately, I did my Ph.D on this topic in Switzerland. As I was completing my studies, endosymbionts emerged as a tool potentially to control vector-borne disease. I began to think that it could be possible to do insect symbiont research that may have real impact. It was a big shift for me, moving back to Kenya, about 6 years ago now, where I was able to work on endosymbionts on disease vectors, to see if any of them could block the transmission of diseases. That took me back to icipe where this whole project started. I decided that not enough work has been done on symbionts of mosquitoes in wild and that most of the symbionts we found in mosquitoes colonies maintained in the lab were not particularly interesting. So we went to the field and started to look what symbionts can be found in mosquitoes. We found several, but one of them, for a few reasons, seemed to be quite interesting to us. It was not previously discovered; it was quite common and when in a mosquito it was found to be in high intensity and this was a microsporidian (later named Microsporidia MB). So, we focused on Microsporidia MB and we decided quite quickly to develop an experiment to discover if it has any positive or negative impact on malaria transmission. That is basically the starting point for the paper that was published, where we showed this microsporidia can block malaria transmission.
Who are the members of your research team?
Everything we do is a massive team effort. We had a team of students at icipe who did most of the work and the key experiments. It is three Kenyan students, notably Lilian Mbaisi, Enock Mararo and Edward E. Makhulu. They are all co-authors of the paper. They were extremely hard working and spent many months in the field collecting mosquitoes and tending to them in the laboratory. We also had international collaborators that brought in key expertise. For example, we benefited from the wealth of experience our collaborators at the Sanger Institute in the UK have on RNA/DNA sequencing and analysis. We also had collaborators from University of Glasgow who were able to do some key molecular characterization experiments. Altogether, we had very good collaboration with the different institutions. For example, Enock Mararo to spend quite some time in Glasgow and in UK and he worked closely with our collaborators there, and also some collaborators came to Kenya for part of the research. So, we were able to work in different places and together. That makes things very easy, everyone was helpful and did their part. I think it was a very smooth experience with the different collaborators.
What led you to take an interest in this specific mosquito symbionts?
The work was largely inspired by a number of projects in the last decade showing that a bacteria (Wolbachia) symbiont could block the transmission of dengue fever. Given the power of that strategy, we really wanted to develop something similar for malaria. We decided to look in malaria mosquitoes for bacteria that has similar characteristics to Wolbachia and even any other bacteria the potential to be a bit like Wolbachia (heritable and intracellular). We started looking through mosquitoes and I should be able to say we spent a year without much success. We got a lot of our assays showing high amounts of Microsporidia and we realized that this is something interesting which needed to be studied. Eventually, we pretty much shifted our entire focus to microsporidia and that is really where we started getting much more interesting results.
How did you and your colleagues get to the discovery of this new microbe in wild populations of Anopheles mosquitoes?
As I said, we were looking for other symbionts and we kept getting this Microsporidia. We thought maybe we should shift and try to see if this Microsporidia is common and what it’s doing? At that point, we started looking in different populations and found that it was something that was present all over. We started doing microscopy so we can really see it and what tissue it infected. Finally, we started experiments to get Plasmodium infected blood and feed mosquitoes on it and see whether there was any blocking effect. Initially, we were open minded about whether the effect could be positive, negative or neutral. When we did this experiment we were very surprised that we never had a single mosquito that had a single microsporidia that was able to take up the plasmodium, so we were able to demonstrate a very strong blocking phenotype.
How efficient Microsporidia MB is in stopping malaria transmission?
So far, there is evidence that there is very strong blocking effect. We did this experiment under very natural conditions. We were taking patient blood from malaria endemic zones, and under various circumstances we had complete blockage. Then I suspected that the blocking is not quite 100%, but it could be very close to that, which is excellent. But blocking is only one side of the coin, because we now need to find the way to increase the number of mosquitoes that have microsporidia. And if we readily get 50%+ of all mosquitoes in sample site infected with Microsporidia MB then achieving this kind of spread will be more important than the strength of blocking effect. So that is the foundation we are building on and we were trying to find ways to elevate the prevalence of the microbe in mosquito populations.
What do you think can be done to increase the proportion of mosquitoes that carry the symbiont to limit their capacity to transmit malaria?
That is going to keep us busy now and probably for the next two years. I have some speculative theories, but the truth is that we need a lot of hard work to figure out what is the best way to increase the level of this symbionts. I think we might be able to disseminate Microsporidia first in sugar baits or in larval habitat. We found that adult mosquitoes can infect other adults and we believe that it is cause by sexual transmission upon mating. We have been exploring the possibility of rearing mosquitoes and then we only release the males which are heavily infected and then these would infect wild females and of course females transmit the symbionts to their offspring. There is a number of possibilities, so we would try and explore all of them to understand what is best.
How can this research be translated into the health policies of African states?
I think we are still in the early stages of this research, and we need to get to a point where we can demonstrate that this strategy can decrease malaria burden in an area. And once we have done that, then we have a new tool which targets the malaria transmission cycle at a different point from other currently used measures (IRS, bednets). This would then be something which I hope could be integrated in other vector-control strategies and that is when we would then look at it from a policy perspective. I think at this point, it’s important that policy makers understand what we are doing and why we are doing this research so that they can also understand the result that will be coming down the pipeline. My hope is that this could be quickly adopted to really help manage the disease.
Despite progress achieved in the fight against malaria, it continues to cause thousands of deaths in Africa, particularly among children aged 0-5 years. What do you think should be done to completely eradicate this killer disease from the continent?
I think we need more investment. From an economical standpoint, we need to invest more in measures that we currently have, find more efficient ways of deployment, and build on what has been done in the last fifteen years. The other thing we need is to invest in new tools, because the tools we have today will not be sufficient to eradicate the disease. They can control the disease, but to get to that ultimate goal of eradicating malaria, I think we will still need new tools that may came out in the next five to ten years.
A major pandemic, COVID-19, has emerged in the global health world and in Africa and is having a major impact on malaria research. The World Health Organization (WHO) recently warned that any interruptions in malaria control efforts could increase malaria incidences and impact. Can you tell us how this health crisis poses a serious challenge to your research?
The world is being interrupted by this pandemic and presenting many challenges to our research. This pandemic is also posing a big challenge to ongoing malaria control effort, and if this is not checked, it could result to many more cases of other diseases. I think that is very concerning, and we need to react quickly but also to learn. There will be more unexpected phenomena like this, so we need our research and health systems need to be more robust. It is unlikely to be the last pandemic, there will be others and we need to make preparations and continue to do work and to control other diseases throughout these difficult times.
(Interview conducted by Junior Matock, Communications Officer, PAMCA)
At the tender age of seven, I was told in the most derogatory sense –your education will only end up in the kitchen. This instead spurred me onto the opposite trajectory buthas been an uphill task. Growing up, I was curious about the diversity and functioning systems of living things. How on earth did a caterpillar become such a colorful insect? How did insects pollinate plants and how did plants take in nutrients from the soil? This curiosity led me to read biology education as my first degree, which exposed me to the morphological differences in the developmental phases of some insects especially mosquitoes-our resident enemy. Malaria, a matter of life and death, inflicted upon humanity by an insect so small one would naturally ignore it. However, unlike the sister, Yellow fever – another disease transmitted by Aedes mosquito, an insect with white stripes on the legs – malaria has no vaccine.
I have survived, I have watched my children battle and survive the malaria experience, episode after episode. Thus, when I had a chance to further my studies, I went for a master’s degree in Applied Entomology and Parasitology with a project on Aedes (Stegomyia) aegypti. Thereafter, as a vital necessity, I finally took on Anopheles gambiae sl for a full time Ph.D. research in Medical Entomology and Parasitology. At the start of my Ph.D program, I was queried thus : Why take all that road risk into fragile and volatile rural areas abandoning your family to study a tiny insect, why not study elephant.
During my Ph.D. field work picking up indoor resting mosquitoes, adult males in my team were prohibited from entering some female private rooms, however, I was granted access. In the course of the asymptomatic malaria cross-sectional survey, participants were told that subjects that were pregnant would be sent to their doctors for special medication if they are tested positive to malaria from the rapid diagnostic test on the field. In communities where cultural norms prevented women from speaking with men, they freely but discreetly notified me of their yet to be visible pregnant status. More women than men queued up with all their children and some were ready to fight for their children to be tested and treated. In the same vain, women provided me with essential and sometimes sensitive details that gave me insight into the determinants, distribution pathways, and home management of diseases afflicting them.
My trajectory into medical entomology instead of ‘elephantology’ is an inescapable imperative. Curiosity is satisfied, but the battle is not over. Since the insects are not done, my work is not yet done. The typical African girl child must overcome near insurmountable barriers to attain education, more so higher education in the sciences. The roadblocks require tons of courage, resilience, and huge financial sacrifice to achieve anything meaningful. Against all odds I have been able to contribute valuable data to the malaria database being the first female entomologist from my village! Heads up fellow females – DON’T GIVE UP !
Parasitology department at the Noguchi Memorial Institute for Medical Research in Ghana. I have been at the forefront of the teaching and research into vector-borne diseases in Ghana and beyond. In January this year, I was in the US as part of an international visitor’s leadership Program (IVLP) sponsored by the US State Department visiting many research and mosquito control agencies in Houston, Texas, New Orleans in Louisiana and University of Florida in Florida state. Just two weeks into the program, we had to stop and get back to our countries. Why? Because of the increase in COVID-19 cases globally. It was not safe for us to remain in the US. Back to my own country, I had to go into quarantine for two weeks and before I could finish the self-isolation, there was an announcement of a three-week lockdown by the government in my country. Things happened very fast that I could not at the time appreciate the enormity of the challenge ahead of my research activities. Prior to the introduction of the SARS-COV-9 virus into my country, I had just won a bid to host the 7th annual meeting of the Pan-African Mosquito Control Association (PAMCA) meeting in Accra. I had set up a local organizing team and we were in touch with the PAMCA secretariat in preparation for the meeting in September 2020. The annual conference has now had to be postponed to next year 2021 because of COVID-19.
I am a medical entomologist and the head of the Parasitology department at the Noguchi Memorial Institute for Medical Research in Ghana. I have been at the forefront of the teaching and research into vector-borne diseases in Ghana and beyond. In January this year, I was in the US as part of an international visitor’s leadership Program (IVLP) sponsored by the US State Department visiting many research and mosquito control agencies in Houston, Texas, New Orleans in Louisiana and University of Florida in Florida state. Just two weeks into the program, we had to stop and get back to our countries. Why? Because of the increase in COVID-19 cases globally. It was not safe for us to remain in the US. Back to my own country, I had to go into quarantine for two weeks and before I could finish the self-isolation, there was an announcement of a three-week lockdown by the government in my country. Things happened very fast that I could not at the time appreciate the enormity of the challenge ahead of my research activities. Prior to the introduction of the SARS-COV-9 virus into my country, I had just won a bid to host the 7th annual meeting of the Pan-African Mosquito Control Association (PAMCA) meeting in Accra. I had set up a local organizing team and we were in touch with the PAMCA secretariat in preparation for the meeting in September 2020. The annual conference has now had to be postponed to next year 2021 because of COVID-19. I had made arrangements with my collaborators in the US who were to visit Ghana in April to launch a five-year integrated vector surveillance project in northern Ghana which includes malaria. That activity had to be shelved for now because the borders are closed as part of the COVID-19 restrictions. All my research plans spanning March to April 2020 have been postponed until further notice. I have been at the forefront of advocating for Aedes surveillance activities within the West African sub-region through the West African Aedes Surveillance Network (WAASuN). We had to put on hold the holding of the annual meeting which was scheduled to be held in July 2020 in Côte d’Ivoire. The worse part of the situation was that my institute was commissioned as the prime COVID-19 testing center and at the peak of the pandemic. As part of this directive, I had to ask all my staff to support laboratory testing of the SAR-COV-2 virus. So, for close to four months, I have not had staff to support my research work. As part of my research work, I provide technical support to the National Malaria Control Program. Considering the call from WHO for countries to ensure the continuity of malaria services in the context of COVID-19 pandemic, we have had to strategize and continue the planned vector control activities in the country. This is being done within the framework of the COVID-19 prevention guidelines. We are currently planning to carry out long-lasting insecticide treated nets (LLIN) durability monitoring and insecticide resistance monitoring in some areas in Ghana which had been delayed for two months due to COVID-19. This will be done with strict adherence to COVID-19 prevention guidelines and protocols. The resumption of all the research activities is to ensure that we do not witness an increase in vector-borne diseases such as malaria, dengue, filariasis etc. post-COVID-19. Currently, we have had to resort to training and planning of our research activities virtually via zoom and other platforms. I have been working from home for the past two months with the attendant challenge of having good internet connectivity and data services. The negative impact of COVID-19 on my research activities cannot be overemphasized and there is a growing concern that COVID-19 is going to be with us for some time. This calls for some innovation and new ways of carrying out our research whilst making sure we do not compromise on generating quality research data that will inform policy and mitigate the fatalities that may affect our people during and after the COVID-19 pandemic. We are not in normal times and so let us protect ourselves, families and communities whilst carrying out our research activities in the midst of the COVID-19 pandemic.
Dear PAMCA colleague, partner & friend,
You will be aware that the ongoing COVID-19 pandemic has now affected nearly every country across the globe. At PAMCA we have been closely monitoring the situation to make an informed decision about whether to go on with the 7th Annual Conference and Exhibition.
After careful deliberation with PAMCA’s Board of Directors, Local Organising Committee colleagues and partners, we have taken the decision to postpone the conference initially planned to take place on 21-23rd September 2020 in Accra, Ghana.
We have agreed that the Annual Conference & Exhibition will now take place in 2021; and we will communicate the precise dates in the coming months. This postponement also applies to all pre-conference workshops that were scheduled to take place this year.
We understand that some of you will have submitted abstracts via our online portal. You will have the possibility to revise the submitted abstracts via our website for next year’s conference. If you have any further questions, please contact us on email@example.com
After a successful conference last year in Yaoundé, we know that many of you will have been hoping to join us this year in Accra, but we felt that current events and the pressure that venues, organisations and countries are under, meant the event would not be viable this year. Your health and wellbeing is also of paramount importance to us.
We are closely monitoring the situation, and will be in touch again in the coming months for updates. Wishing you, your family, friends, and organisations our best wishes at this challenging time.
Dr. Prosper Chaki, Prof. Charles M. Mbogo,
Executive Director, PAMCA, President, PAMCA Board of Directors,
Pan-African Mosquito Control Association (PAMCA)
It’s time to stand united and say No to NTDs!
On January 30th, PAMCA joins the global health community to celebrate the first-ever World NTD Day, and mark the beginning of a decisive year in the fight to eliminate Neglected Tropical Diseases. This new awareness day brings together global health experts, civil society advocates, community leaders, and policymakers to help end NTDs for good.
We are committed to support this campaign and look forward to joining our partners to launch the World NTD Day and highlight the impact of NTDs around the globe. Thank you to everyone who has been at the frontline supporting the activities so far, and we hope that we continue the journey together as we mark the day this Thursday!
On January 15, 2020, the Aspen Institute in Washington DC announced the 2020 class of the New Voices Fellowship, a groundbreaking program that equips experts from developing countries to play a more powerful role as advocates and policymakers in the global development discussion.
“New Voices Fellows are uniquely positioned to influence global development policies,” Fellowship Director Andrew Quinn said. “Their world-class expertise, paired with lived experience of basic development challenges, gives them important insight into how policy can translate into progress on the ground.”
The 2020 Class of New Voices Fellows includes 25 Fellows from 16 African, Asian and Latin American countries.
Damaris Matoke-Muhia has been selected as an Aspen New Voices Fellow, 2020! Damaris is a senior research scientist at Kenya Medical Research Institute (KEMRI) & Director of capacity Building, Gender Mainstreaming, and Career Progression, Pan-African Mosquito Control Association (PAMCA) undertaking research in vector-borne diseases control.
She holds a PhD in Molecular Medicine and a Masters in Biotechnology. In addition to her extensive experience working in disease prevention and vector control, Damaris is passionate in mentoring young career scientists and advocates for the advancement of the careers of women scientists.
The entire PAMCA community takes this opportunity to congratulate Damaris for being selected as an Aspen New Voices Fellow!