Epidemiological Status of Leptospirosis in India

Epidemiology of acute undifferentiated febrile illness and acute encephalitis syndrome cases in Northern India: a prospective observational study

PURPOSE

Acute undifferentiated febrile illness (AUFI) and acute encephalitis syndrome (AES) continue to be major public health concerns, particularly in rural areas with limited healthcare facility. We investigated the aetiological agents responsible for seasonal sporadic AUFI and AES cases in Northern India.

METHOD

The study included 4200 patient samples (April 2022 to March 2024), fulfilling the AUFI or AES case definition. Clinical samples were tested for IgM antibodies against dengue, chikungunya, Japanese encephalitis, scrub typhus, and leptospirosis. Further, Leptospira IgM ELISA positives (n = 79) were also tested by microscopic agglutination test (MAT) assay.

RESULTS

In AUFI cases, scrub typhus was the predominant bacterial aetiology (24.6%, 593/2407) followed by leptospirosis (12.4%, 266/2151). Dengue (23.0%, 321/1398) was the leading cause among viral aetiologies. Similarly, among AES cases, scrub typhus (36% in cerebrospinal fluid and 34.3% in serum) remained the most common bacterial aetiology followed by leptospirosis (5.42%, 11/203). Whereas, chikungunya was the predominant viral cause (5.4%, 17/314) behind AES cases. Further, using MAT assay, 7.6% (6/79) of the AUFI samples tested positive for leptospirosis. The prevalent serogroups identified included L. interrogans serovars Australis, Pomona, Hebdomadis, Pyrogenes and Djasiman, and L. borgpetersnii serovar Tarassovi. Housewives constituted the primary risk group for leptospirosis infection, followed by individuals engaged in various farming practices.

CONCLUSION

This study identifies scrub typhus as the predominant and leptospirosis as the second most common infection in sporadic cases of AUFI and AES. Therefore, continuous monitoring of changing aetiologies is crucial for the effective implementation of targeted control and preventive measures for neglected tropical diseases.

Mapping serogroup distribution and seroprevalence of leptospirosis in livestock of Assam, Northeastern State of India: Unveiling uncommon Leptospira serogroups

Leptospirosis is a significant zoonotic disease affecting livestock, leading to reproductive issues and economic losses. Despite its endemic status in India, research has predominantly focused on coastal regions, leaving the North Eastern Region (NER) underexplored. This study aims to investigate the seroprevalence and serogroup distribution of leptospirosis in livestock across Assam, a major state in the North Eastern Region (NER) of India. Serum samples (n=811) from cattle, buffalo, sheep, goats, and pigs were collected between 2016 and 2019 and screened using the Microscopic Agglutination Test (MAT) for 24 serogroups. The overall seroprevalence was 22.9 % (186/811), with highest prevalence in cattle (26.2 %) and buffalo (25 %), followed by small ruminants (19.8 %) and pigs (18.6 %) . Notably, uncommon serovars such as Mini (28.8 %), Manhao (12.4 %), and Cynopteri (7.5 %) were identified, indicating a unique epidemiological pattern in Assam. High seroprevalence was observed in districts like Bongaigaon (66.7 %), Kamrup Metropolitan (50.0 %), and Nalbari (40.0 %), emphasizing the need for targeted intervention strategies. The presence of these uncommon serogroups, typically found in neighbouring countries and other regions, suggests potential transboundary transmission from these countries. This study provides valuable insights into the seroprevalence and serogroup distribution of leptospirosis in Assam's livestock, highlighting the need for region-specific surveillance and control measures. These findings underscore the importance of understanding the local epidemiological landscape to develop effective disease management and prevention strategies, ultimately reducing the impact of leptospirosis in the NER of India.