An overview of Dr Charlena doctoral research in Mauritius

Dr. Charlena Poonyth provided a comprehensive overview of her proposed investigation into ruminant health and vector-borne diseases in Mauritius for the upcoming years. In Mauritius, ruminants—cattle, sheep, goats, and deer—are the quiet pillars of the national economy. They represent the primary livelihood for thousands of farmers, breeders, and butchers.

 The Silent Carriers: When "Mild" for Cows Means "Lethal" for Humans

The most dangerous pathogens are often the most deceptive. Crimean-Congo Haemorrhagic Fever (CCHF) is a prime example. In cattle and sheep, CCHF is remarkably "silent," typically manifesting as nothing more than a transient fever or mild lethargy. A farmer might see a cow that looks slightly "off" for forty-eight hours and think nothing of it.

However, CCHF is a severe zoonotic threat. In humans, this virus—a member of the Nairoviridae family—causes a devastating haemorrhagic disease with high mortality rates. Epidemiologically, we must also look at its genetic relatives to understand the full scope of the risk; for instance, Nairobi Sheep Disease is serologically and genetically related to CCHF, causing similar haemorrhagic symptoms and high mortality in small ruminants. When these "silent" reservoirs maintain a high viraemia (virus in the blood), they become a ticking clock for a public health crisis.

"There is an URGENT need for public health strategies!!!"

This urgency exists because clinical signs in animals are often insufficient for detection. By the time we see a human patient bleeding in a clinic, the virus has likely been circulating in the livestock population for weeks.

Cultural Crossroads: The High-Risk Intersection of Tradition and Pathogens

Effective public health must be a bridge, not a barrier. In Mauritius, the Eid-ul-Adha festival is a vital religious tradition involving the sacrifice of ruminants. However, from an epidemiological standpoint, it represents a high-risk intersection of human activity and potential pathogens. The process of slaughtering—severing the jugular veins and carotid arteries of a live animal—can result in "blood gushing out," creating a significant risk of infection through direct contact or aerosolized fluids.

The goal of modern surveillance is not to eliminate these traditions, but to shield the community through specific biosafety measures and the use of personal protective equipment (PPE) for those grooming and slaughtering. We have identified four primary risk factors during such large-scale events:

• Uncontrolled animal movement across different districts and islands.
• Crowding of humans and livestock in confined spaces.
• Large-scale self-slaughter and traditional butchery outside regulated facilities.
• Direct contact with infected blood, tissue, and amniotic fluid.

Mauritius’s Surprising Inhabitants: A Wild and Domestic Mosaic

Mauritius presents a unique host "mosaic" that complicates disease surveillance. While cattle and goats are common, they are dwarfed by a massive population of wild deer. This creates a complex bridge for emerging pathogens like Epizootic Haemorrhagic Disease (EHD). Historically a disease of wild ruminants—specifically deer—EHD is now an emerging threat in cattle. In an environment where 65,000 deer live in the same ecosystem as 4,000 cattle, the deer act as a massive, wild reservoir for viruses that can devastate the domestic dairy and beef industry.

The following headcount reflects the ruminant landscape as of 2025:

Species	Mauritius	Rodrigues
Sheep/Goat	26,000	26,000
Cattle	4,000	8,000
Deer	65,000	-

Despite its geographic isolation, Mauritius is an international hub, importing livestock from Kenya, South Africa, and Australia, as well as managing inter-island movement from Rodrigues and the regional context of La Reunion. Without a dedicated university for veterinary medicine, the island sits in a precarious position, relying on international partnerships to monitor the pathogens arriving at its shores.

Beyond the "Heartwater": The Complexity of Differential Diagnosis

One of the greatest challenges for island veterinarians is the "Diagnostic Challenge"—the fact that many vector-borne diseases (VBDs) look identical to the naked eye. Heartwater Disease (Ehrlichia ruminantium) and Anaplasmosis (often called "Gall Sickness") both present with high fever and depression.

In Heartwater, the pathogenesis is particularly striking: the pathogen multiplies within immune cells until they rupture, releasing organisms into the bloodstream and causing severe vasculitis. This inflammation of the blood vessels leads to "pericardial effusion"—a massive accumulation of fluid around the heart. To an observer, the animal may show "eyelid twitching," "protrusion of the tongue," or seizures.

Because the treatment for Heartwater (tetracyclines) differs from Anaplasmosis (imidocarbs), we cannot rely on broad-spectrum guesses. Active surveillance and targeted therapy are the only ways to prevent the rise of Antimicrobial Resistance (AMR). Using the wrong drug for a non-specific symptom doesn't just fail to save the animal; it strengthens the pathogens against our future medical arsenal.

The 2026 Pioneer Movement: Mapping the Future

To fill the void of missing statistics and outdated research, a landmark sampling mission is scheduled for February 2026. This pioneer movement aims to establish the first comprehensive, nationwide database of VBDs in Mauritius, spanning all 9 districts.

The framework is meticulously designed to pair specific vectors with the pathogens they carry:

• Target Vectors: Collection of Hyalomma ticks (the primary vector for CCHF), Amblyomma ticks (the vector for Heartwater), Aedes and Culex mosquitoes (Rift Valley Fever), and Culicoides biting midges (Bluetongue and EHD).
• Sample Size: 200–300 whole blood samples (EDTA) from cattle, sheep, and goats.
• Methodology: Integration of an epidemiological questionnaire with high-accuracy diagnostic tools to identify transmission trends.

This study will finally bring the island to international standards, providing the data necessary to identify where these diseases are originating and how they are moving across the landscape.

Conclusion: The Cost of Isolation

In a globalized world, the concept of a "protected island" is a myth. The geographical distance that once served as a barrier now creates a dangerous silence. Without active surveillance, a pathogen can establish itself in the "wild mosaic" of the deer population or the silent reservoirs of the sheep pens long before the first human outbreak occurs.

Outbreak preparedness is not merely a scientific endeavor; it is an economic and humanitarian necessity. As we prepare for the 2026 survey, we must confront a sobering reality: our food systems and our health are only as secure as our surveillance of the invisible threads that connect us. If the silent ruminants of Mauritius are the sentinels of our future, are we finally ready to listen to what they are telling us?