Epidemiology and Management of Typhoidal Salmonella Infections

Typhoidal Salmonella, comprising Salmonella enterica serovars Typhi and Paratyphi A, remains a major cause of enteric fever in low- and middle-income regions. Transmission occurs primarily via ingestion of contaminated food or water in settings with inadequate sanitation and water treatment. Incidence is highest among children and young adults, with sporadic outbreaks linked to population displacement and mass gatherings. The global burden has declined in recent decades but remains substantial, with millions of cases annually and persistent hotspots in South Asia and sub-Saharan Africa. Antimicrobial resistance has progressively undermined treatment, evolving from multidrug resistance to extensive drug resistance (XDR) in some settings, narrowing therapeutic options and heightening the risk of complications. Management strategies combine improved water, sanitation and hygiene (WASH) infrastructure, rational antibiotic use guided by susceptibility testing, and vaccination. Typhoid conjugate vaccines (TCVs) targeting the Vi capsular polysaccharide have demonstrated durable efficacy in infants and older children, supporting their introduction into routine immunisation schedules. Concurrently, enhanced surveillance through blood culture networks and molecular methods—including whole-genome sequencing—enables real-time tracking of strain emergence and transmission pathways, informing targeted public health interventions.

Research from Nature Portfolio

Recent large-scale phylogeographic analysis has quantified the global risk of XDR Salmonella Typhi importation by integrating air-travel data with estimates of regional disease incidence. These findings highlight countries with strong travel links to endemic foci as priorities for enhanced surveillance and pre-emptive vaccine campaigns. In parallel, an extended genotyping framework based on whole-genome sequence data has refined the classification of S. Typhi into phylogenetically informative subclades. This scheme supports rapid identification of outbreak sources, geographical tracking of H58 and other lineages, and delineation of local versus imported strains, thereby guiding containment efforts and resource allocation.

Epidemiology and Management of Typhoidal Salmonella Infections publication trend

The graph below shows the total number of articles in epidemiology and management of typhoidal salmonella infections across all publications each year (not limited to Nature Index journals).

Technical terms

Typhoid conjugate vaccine (TCV): A vaccine in which the Vi capsular polysaccharide of S. Typhi is chemically linked to a protein carrier, eliciting strong, long-lasting immunity even in infants.

Extensively drug resistant (XDR): Describes bacterial strains resistant to multiple first-line antibiotics as well as key second-line agents, limiting effective treatment options.

Phylogeography: The study of the historical processes governing the geographic distribution of genetic lineages, often using genome sequence data to infer transmission routes.

Haplotype: A combination of alleles or sequence variants at adjacent positions on a chromosome that are inherited together, used to track related pathogen strains.

Antimicrobial resistance (AMR): The ability of microorganisms to survive or proliferate in the presence of drugs that would normally inhibit or kill them, complicating infection management.

References

1. The global burden of typhoid and paratyphoid fevers: a systematic analysis for the Global Burden of Disease Study 2017. The Lancet Infectious Diseases (2019).
2. Emergence of an Extensively Drug-Resistant Salmonella enterica Serovar Typhi Clone Harboring a Promiscuous Plasmid Encoding Resistance to Fluoroquinolones and Third-Generation Cephalosporins. mBio (2018).
3. Efficacy of typhoid conjugate vaccine: final analysis of a 4-year, phase 3, randomised controlled trial in Malawian children. The Lancet (2024).
4. Incidence of typhoid fever in Burkina Faso, Democratic Republic of the Congo, Ethiopia, Ghana, Madagascar, and Nigeria (the Severe Typhoid in Africa programme): a population-based study. The Lancet Global Health (2024).
5. Pathogen diversity and antimicrobial resistance transmission of Salmonella enterica serovars Typhi and Paratyphi A in Bangladesh, Nepal, and Malawi: a genomic epidemiological study. The Lancet Microbe (2024).
6. Assessing the global risk of typhoid outbreaks caused by extensively drug resistant Salmonella Typhi. Nature Communications (2023).
7. An extended genotyping framework for Salmonella enterica serovar Typhi, the cause of human typhoid. Nature Communications (2016).