Their names are Florian, Muriel, Andres, Veerle, Louis-Clément... Each morning, a community of IRD researchers working in Southern, Eastern Africa and the Indian Ocean wakes up with a simple idea in mind: fighting communicable diseases which have significant effects on the region’s populations.

Their targets: malaria, dengue, sleeping sickness, coronaviruses, tuberculosis etc. Their mission: to study these diseases, their transmission or their treatments in order to find sustainable solutions to protect the people and the environment. Their main assets: the fair partnership with researchers from the Global South and the involvement of local populations in research projects.

A few figures show the extent of their challenge. 65 million people are at risk of catching sleeping sickness (Human African Trypanosomiasis, transmitted by the tsetse fly) in 36 endemic countries in Africa? 91% of malaria deaths in 2010 occurred in Africa? In 2014, it was estimated that dengue could infect more than 2.5 billion people?;jsessionid=1960192B1434A44C89FC12EF97F012BB?sequence=1. The most recent epidemic, caused by SARS-CoV2 in 2020, has taken 6746 African lives as of 5 July (WHO).

The One health approach.

© Agropolis

Faced with these non-exhaustive observations, the World Health Organization has chosen an integrated approach: "One World, One Health". This concept states that human health, animal health and the environment are interconnected. Therefore, and particularly due to the recent acceleration in the emergence of new infectious diseases, efforts must be made to tackle simultaneously these three aspects in order to guarantee a sustainable health for all.

"Communicable disease research is one of IRD's priorities in the region, following the One Health approach. The involvement of local health workers in all projects is a main focus for researchers." said Jean-Pascal Torréton, IRD representative in South Africa.

The projects carried out in the region cover multiple dimensions: from the knowledge of the characteristics of pathogens to the implementation of treatments, including the study of the reservoirs and vectors of these diseases and human-animal transmission mechanisms. The researchers also take into account the influence of ecosystems on diseases and the capacity of national health systems to manage epidemics.

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© IRD - Vincent Jamonneau

Sampling for sleeping sickness diagnosis.

Veerle Lejon, a researcher at the Intertryp unit, is for example participating in clinical trials for a new treatment for sleeping sickness in Uganda and Malawi: "after years of research, trials are currently underway to provide better care for patients. Other treatments already exist but have many side effects." said Veerle.

From conducting fundamental research to implementing concrete solutions, our researchers are working on all fronts. Follow a few of them in their daily work.

The Aedes aegypti mosquitoe is one of the main vectors of dengue, Zika, chikungunya and yellow fever.

© IRD - Nil Rahola

The Aedes aegypti mosquitoe is one of the main vectors of dengue, Zika, chikungunya and yellow fever.

High-speed pathogen connection

Carrying their backpacks, lighting the path with their headlamps and holding their equipment, the scientists are walking into the night of Reunion Island. Every evening for several weeks, Muriel Dietrich and her colleagues leave at sunset to study the only flying mammal of our era. Once arrived at their destination, an electrical transformer home to a colony of bats, the researchers unpack their nets and other traps. Their objective is to capture some specimens of Petit Molosse, an endemic species on the island, and to collect urine, faeces and saliva samples, before releasing them.

"Bats are the reservoir of a number of infectious agents that we study. They can for example carry the Leptospira bacteria” explained Muriel. Tracking different bat colonies in Reunion and Madagascar helps the researchers to understand the organization and structure of populations, their reaction to environmental changes and their interactions with infectious agents. As with other projects in the region, this study allows to identify the diseases to which humans and animals could be exposed. “Bats are often mistakenly considered pests. In reality, they play a fundamental role as regulators of the number of insects on which they feed, and are also involved in the dispersion of pollen and seeds", clarified Muriel.

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© CapCom21

Scientists work at night to collect samples on bats.

If some animals act as reservoirs for infectious agents, how are diseases transmitted between the environment, animals and humans? This is where some vectors come into play. From the reservoir to humans, or from humans to humans, messengers such as mosquitoes carry infectious agents. IRD researchers and their partners in the region are working to understand how vectors work, what pathogens they carry, and what fosters transmission.


A few kilometers from Muriel and her team, other IRD scientists aim to monitor and control the tiger mosquito populations in Reunion using the Sterile Insect Technique (TIS). This biological control method reduces the number of mosquitoes that carry chikungunya or dengue on the island. The principle is to sterilize male laboratory-raised mosquitoes (which do not sting). Once released, they cannot give birth to offspring and the population drops.

The first sterile mosquitoe launch took place in June 2019.


After a few years developing and improving the technique, Louis-Clément Gouagna and his team are soon starting the field tests: “In 2021, we will launch sterile mosquitoes mass release tests in a district of Sainte-Marie (town in Reunion). If the method proves to be effective and if it is accepted by the populations and the authorities, we can implement it on the whole territory of the island and thus fight against epidemics transmitted by mosquitoes”. Started as a local project in Reunion, TIS is now developing in the region. An ongoing project will determine whether it is possible to use the same technique in Kenya, Mauritius and Madagascar.

Like Muriel and Louis-Clément, many researchers focus on the reservoirs and vectors of communicable diseases in the Indian Ocean and East and Southern Africa. Better understanding of pathogens, their reservoirs and the vectors of transmission to humans or animals and their interactions contributes to an integrated approach to global health.

Domestic animals in Zimbabwe.

© IRD - Eve Miguel

Domestic animals in Zimbabwe.

Humans, wildlife and domestic animals: an interlinked destiny

Did you know that between 60 and 70% of emerging and re-emerging diseases affecting people result from a transfer of pathogens from domestic or wild animals? Ungulate mammals, carnivores, rodents and even primates top the ranking by transmitting most zoonotic diseases.

Prevention sign for foot-and-mouth disease in South Africa.


Eve Miguel and Florian Liégeois have this in mind and work at knowing more about animal and zoonotic (transmitted to humans by animals) diseases and the relationships between ecosystems and health. "In Zimbabwe, and it is also the case in Southern and Eastern Africa, contacts between wildlife and people are intensifying. Climate change and political crises are encouraging people to use protected areas as refuge areas to access resources such as water or pasture for subsistence farming,” explained Eve Miguel, ecologist and epidemiologist in the MIVEGEC research unit.

These risks add up to biodiversity loss, temperature increase and rainfall decrease, modifying the contact networks between hosts of potential pathogens, particularly in cross-border conservation areas where animals and humans coexist. The risks for wildlife, livestock and humans to be exposed to infectious diseases thus tend to change.


Bats carry coronaviruses

In order to investigate and understand these changes, scientists travel around Zimbabwe, its urban and rural areas and its national parks. GPS collars, camera traps and syringes are part of their tools. They are used to study the behaviour and movements of wild animals populations (ungulates such as buffaloes; bats; rodents etc.) and to collect saliva, faeces and blood samples. Once the scientists are back at the molecular biology laboratory recently brought up to international standards in Harare, these samples are analysed to detect possible pathogens and understand their transmission mechanisms.


© IRD - Jean-Louis Duprey

Zimbabwean and French researchers identified different types of coronaviruses in two colonies of insectivorous and cavernous micro-bats in the Kwekwe and Hurungwe districts, in Central and Northern Zimbabwe.

Some diseases such as Covid-19 can have serious health and economic consequences for Zimbabwe and the region. An epidemic affecting livestock would cost the population a part of its livelihood. Covid-19 is one example of zoonose transmitted from animal to humans resulting in heavy loss of life." specified Florian Liégeois. Better knowing the pathogens animals carry makes it possible to react better when facing the next similar epidemic. "We are working with our partners to strengthen Zimbabwe's capacity to cope with this type of event and to detect pathogens as soon as possible."


In neighbouring countries as well as in Zimbabwe, researchers are putting the emphasis on the knowledge of pathogens present in wild and domestic animals in order to contribute to the One Health global approach and thus fight epidemics.

A man gets his temperature checked at an hospital in Bulawayo, Zimbabwe.

© International Labor Organization

A man gets his temperature checked at an hospital in Bulawayo, Zimbabwe.

Being prepared for epidemics

Ifanadiana, a small town in eastern Madagascar. Here, as in most regions of the island, infectious diseases are frequent and have serious consequences. Malaria, tuberculosis, HIV, neglected tropical diseases, plague, etc.: one of the poorest people on the planet has few means to cope with successive epidemics.

Andres Garchitorena chose to settle in Ifanadiana, in order to study the conditions that encourage the prevalence of these various diseases. “Tackling infectious diseases in Madagascar, and throughout the region, requires better access to quality care for all. The economic situation, the quality of the healthcare system and the difficulty to access health centres play a crucial role in the management of epidemics," he explained.

Equipped with good shoes, his backpack and accompanied by his partners from the PIVOT NGO, Andres is leaving his office to meet with the inhabitants of the district. The objective is to better understand their habits: “since 2014, we have been collaborating with the National Institute of Statistics to follow more than 8,000 people in the district, i.e. 1,600 households. This helps us to understand how often they seek care, for what pathology and above all what are the results of governmental and NGOs policies.” he explained. On the way, he stops at one of the health centres which are monitored: "we collect various information such as the number of consultations, the resulting diagnoses, the patient’s profile and their geographic origin", he continued.

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Scientists visiting Ifanadiana hospital.

Back at the office, the researchers are carefully observing the satellite images of the area. After having made the link with the population social data and the health centres statistics, they can draw up a complete overview of access to care in the district. Geographical and climatic obstacles (vegetation, flood), long journey times (distance, dirt roads) and financial constraints are elements that can lead people to renounce care.

One of the biggest barriers to eliminating infectious diseases in the district is poverty. A study has indeed shown that the introduction of fee exemptions significantly increased the number of visits in health centres (+ 65%), especially for pregnant women and children under 5. Government and NGO interventions thus have a large impact and the creation of universal health coverage should be encouraged.

Laboratory practical training session in Zimbabwe.

© IRD - Veerle Lejon

Training as a priority

The quality of care and the management of epidemics also depend on the training of health personnel. Whether they are community workers chosen by populations or doctors in clinics and hospitals, they play a key role in the treatment of infectious diseases. Let’s jump to the continent. Veerle Lejon takes part in missions organized by WHO, in collaboration with the Ministry of Health of the country involved, on the African sleeping sickness (HAT) in East and Southern Africa, where medical staff know little about this disease. “There is an urgent need for staff training in the region”, she underlined. The project provides training in Zimbabwe, Zambia and South Sudan on the diagnosis of HAT, prevention, management of the tsetse fly (its vector), the different stages of the disease and the corresponding treatments. Still in Zimbabwe, other IRD researchers are also contributing to the training of veterinary services staff on animal disease control through the CAZCOM project. In Madagascar, IRD scientists encourage the training of community workers for better management of malaria.


Training, access to care and health system quality are an integral part of the fight against infectious diseases in the area. In different disciplines, IRD researchers act concretely and on a daily-basis to ensure sustainable population, animal and environmental health.

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