Why Hepatitis A is no longer a simple disease in Kerala

Hepatitis A is no longer a straightforward disease in Kerala, according to clinicians and public health experts. The state has seen explosive outbreaks of the disease in recent years, resulting in increased mortality and morbidity. Rather than the traditional pattern of Hep A affecting children, the susceptible population in Kerala has shifted to young adults.

Doctors are reporting severe and atypical symptoms in those affected, including prolonged high liver enzyme levels and extra-hepatic complications such as bone marrow suppression. Many young adults are experiencing fulminant hepatitis, which requires liver transplantation.

In 2024, Kerala reported 28,412 confirmed and probable cases of Hep A and 96 deaths, with 12,437 cases and 125 deaths so far this year. The Malappuram-Kozhikode belt continues to be the hub of water-borne infectious diseases, particularly Hep A and Shigellosis. Clinicians have observed severe Hep A cases with dysregulated or inflammatory responses, necessitating steroid treatments. This immune dysregulation is a phenomenon seen in many infectious diseases, especially post-Covid.

The age shift in Hep A patients is evident, with 90% of the patients falling within the 18-40 years age group. These individuals are vulnerable due to improved socioeconomic status and better sanitation, leading to immunological naivety. A multi-center study in 2024-25 examined 324 adults with confirmed Hep A and found that Kerala is witnessing a shift from a benign childhood illness to a multisystem disease in adults characterized by immune dysregulation, extra-hepatic organ involvement, and higher mortality.

Atypical features such as pulmonary complications, acute kidney injury, and hemophagocytic lymphohistiocytosis were reported in 16.8%, 13.4%, and 12.8% of patients, respectively.

Therapeutic interventions included high steroid use, plasmapheresis, continuous renal replacement therapy, and mechanical ventilation. A recent study published in BMC Infectious Diseases found that adults infected with Hep A later in life had 8.4 times higher odds of moderate-to-severe disease. The immunological profile of infected adults revealed a larger reservoir of CD8 and primed memory T cells, leading to a higher inflammatory cytokine response and an 18% hospitalization rate, compared to zero hospitalization in those under 18 years old.

This study supports the argument for universal Hep A vaccination in Kerala, as there is a biological reason why exposure to HAV in adulthood can be dangerous.