Neuromelioidosis outbreak in Tamil Nadu, India: an investigation of transmission with genomic insights

Miraclin Thirugnanakumar, Angel, Rajkumar, Prabu, Gunasekaran, Karthik, Mannam, Pavithra, Ponnaiah, Manickam, Chethrapilly Purushothaman, Girish Kumar, Velmurugan, Aravind, Raj Neeravi, Ayyan, Jacob, Jobin John, Cruz, Solomon D., Singh, Bhagteshwar, Appaswamy Thirumal, Prabhakar, Jasper, Anitha, Mohan, Malu, Shanmugasundaram, Devika, Abraham, Ananth, Thangarajan, Senthil, Panicker, Tony, Nair, Bijesh, Selvakumar, Aravintharaj, Moorthy, Ranjith K., Joseph, Baylis Vivek, Prabhu, Krishna, Reddy Sirasanambati, Devarajulu, Nair, Shalini, Umapathy, Murali, Pitchamuthu, Kishore, Murugesan, Balusamy, Sathyendra, Sowmya, Hansdak, Samuel George, Paul, Hema, Isaiah, Rajesh, Paul P Abhilash, Kundavaram, Nair, Aditya V., Mathew, Vivek, Sivadasan, Ajith, Thomas, Maya Mary, Aaron, Sanjith, Jude Prakash, John Antony, Chacko, Geeta, Rupali, Priscilla, Solomon, Tom, Anavarathan, Somasundaram, Thirumalaichiry Sivaprakasam, Selvavinayagam, Veeraraghavan, Balaji and Murhekar, Manoj (2025) 'Neuromelioidosis outbreak in Tamil Nadu, India: an investigation of transmission with genomic insights'. The Lancet Regional Health - Southeast Asia, Vol 37, p. 100602.

Text 1-s2.0-S2772368225000733-main.pdf - Published Version Available under License Creative Commons Attribution Non-commercial. Download (1MB)

Abstract

Background
In May 2023, we investigated a cluster of neuromelioidosis notified from Tamil Nadu state in southern India to describe case characteristics and identify the infection source.

Methods
We searched for probable cases presenting with fever and brainstem syndrome, supported by radiological findings suggestive of neuromelioidosis. Cases were confirmed by isolation of Burkholderia pseudomallei from tissue, blood, or cerebrospinal fluid (CSF), or by PCR. The cases were described by time (epidemic curve), place (spot map), and person (clinical characteristics). Infection sources and virulence markers were identified by genome sequencing of the clinical and environmental isolates. Whole genome sequencing data were analysed to investigate the expression of Burkholderia mallei-like bimABm gene, and a phylogenetic tree was constructed to study sequence similarity to the global isolates.

Findings
We identified 21 probable cases between July 2022 and April 2023 (median age = 33 years; 11 females; five confirmed) across four districts in Northern Tamil Nadu. Seventeen cases were from a single district and 10 reported prior dental treatment at a clinic. Cases with dental exposure had higher fatality (8/10 vs. 1/11) and shorter time to death (median 17 days vs. 1 death at day 56) than sporadic cases. The bimABm gene, which is associated with neurotropism, was identified in all three clonal isolates (two from the cases and one from the environmental isolate from the in-use saline bottle). Whole genome sequencing identified the ST1553 strain as being associated with the current outbreak. Genetic analysis of 209 isolates available in the public database with metadata revealed that ST1553, the strain responsible for the outbreak, clustered with isolates from India and Australia that expressed the B. mallei-like bimABm allele.

Interpretation
We confirmed a large cluster of neuromelioidosis from South India, likely representing sporadic cases from environmental sources and cases linked to an iatrogenic source at a dental clinic. Rapid and high case fatality among dental cases supports the direct trans-neural spread of B. pseudomallei to the brainstem following inoculation via contaminated saline. Expression of B. mallei-like bimABm allele may have contributed to the increased neurological manifestations of melioidosis.

Item Type:	Article
Subjects:	QX Parasitology > Insects. Other Parasites > QX 650 Insect vectors
Faculty: Department:	Biological Sciences > Department of Tropical Disease Biology
Digital Object Identifer (DOI):	https://doi.org/10.1016/j.lansea.2025.100602
SWORD Depositor:	JISC Pubrouter
Depositing User:	JISC Pubrouter
Date Deposited:	17 Jun 2025 13:54
Last Modified:	17 Jun 2025 13:54
URI:	https://archive.lstmed.ac.uk/id/eprint/26823

Statistics

View details

Actions (login required)

Edit Item