Kyasanur Forest Disease: Understanding India’s Tick-Borne Viral Threat

Why in News ?

A 29-year-old man in Karnataka recently lost his life after contracting Kyasanur Forest Disease (KFD), commonly known as monkey fever. The incident has brought renewed attention to a disease that often remains underreported until outbreaks turn fatal.

Background: Emergence and Public Health Significance of KFD

Kyasanur Forest Disease is a zoonotic viral illness that primarily affects forest-dwelling populations in southern India. First identified in 1957 in the Kyasanur Forest region of Karnataka, the disease has since remained endemic in parts of Karnataka and has gradually spread to neighbouring States.

The disease highlights the growing interface between human activity, wildlife habitats, and vector-borne infections, making it a key concern in the context of emerging infectious diseases and environmental change.

What is Kyasanur Forest Disease (KFD) ?

Kyasanur Forest Disease is a tick-borne viral haemorrhagic fever caused by the KFD virus, which belongs to:

• Family: Flaviviridae
• Genus: Flavivirus
• Part of the tick-borne encephalitis (TBE) complex.

It is also referred to as:

• Monkey fever or monkey disease, due to its strong association with monkey deaths that often precede human outbreaks.

KFD is primarily reported from southern India, especially forested and semi-forested regions.

Geographical Distribution and At-Risk Populations

Originally confined to Karnataka, KFD has now been reported in:

• Goa
• Maharashtra
• Kerala
• Tamil Nadu

Populations at higher risk include:

• Forest workers
• Farmers and cattle grazers
• Tribal communities
• People living near forest fringes

Seasonal patterns are observed, with most cases occurring during dry months, when human exposure to ticks increases.

Transmission Mechanism

KFD is transmitted through hard ticks, particularly Hemaphysalis spinigera.

Key modes of transmission include:

• Tick bites while working or walking in forested areas.
• Direct contact with infected animals, especially sick or recently dead monkeys.
• The virus circulates in wildlife reservoirs such as monkeys, rodents, and small mammals.

Importantly:

• KFD does not spread from person to person, which limits human-to-human transmission but does not reduce outbreak potential in high-risk zones.

Clinical Features and Disease Progression

KFD typically presents with a sudden onset of symptoms, including:

• High-grade fever
• Severe weakness and prostration
• Headache
• Nausea, vomiting, and diarrhoea
• Muscle pain

In some cases, patients may develop:

• Haemorrhagic manifestations (bleeding tendencies)
• Neurological complications such as altered consciousness or tremors

The disease may follow a biphasic course, where initial recovery is followed by a second phase with neurological symptoms.

Diagnosis and Treatment

Diagnosis

• Confirmed through laboratory tests such as RT-PCR or serological assays in specialised laboratories.

Treatment

• There is no specific antiviral cure for KFD.
• Management is supportive, focusing on:
  • Maintaining fluid and electrolyte balance
  • Oxygen therapy
  • Blood pressure management
  • Treating secondary infections and complications

Early diagnosis and prompt supportive care significantly improve survival outcomes.

Vaccination and Preventive Strategies

A vaccine against KFD is available in India and is recommended in endemic areas.

Key preventive measures include:

• Routine vaccination of populations in high-risk zones.
• Booster doses for sustained immunity.
• Tick control measures, including use of repellents and protective clothing.
• Avoidance of forest areas during outbreaks.
• Public awareness campaigns on safe handling of sick or dead animals, especially monkeys.

Public Health Significance and Way Forward

KFD represents a broader challenge of emerging zoonotic diseases linked to environmental change, deforestation, and human-wildlife interactions.

Going forward, priorities should include:

• Strengthening disease surveillance in forested regions.
• Expanding vaccination coverage in endemic and at-risk areas.
• Enhancing laboratory capacity for rapid diagnosis.
• Promoting One Health approaches, integrating human, animal, and environmental health systems.
• Investing in community education and early warning mechanisms to reduce mortality and outbreak spread.