Typhoid Conjugate Vaccine: An Urgent Tool to Combat Typhoid and Tackle Antimicrobial Resistance

Abstract

Typhoid is endemic in many countries in South Asia and sub-Saharan Africa. The high burden of this age-old, preventable disease exacerbates constraints on the health systems of these countries. Currently, most patients are treated effectively in the community or outpatient departments, however, with rising antimicrobial resistance and the dearth of novel antimicrobials in the horizon, we risk losing our primary defense against typhoid. Extensively drug-resistant Salmonella Typhi is spreading, and azithromycin is the last oral drug to continue treating typhoid in the community. With increasing azithromycin resistance, emergence of pan-oral drug resistant Salmonella Typhi is imminent. The high burden of typhoid is also an underlying cause of the unnecessary use of antimicrobials. In addition to implementing water sanitation and hygiene interventions to prevent typhoid, it is imperative to rapidly roll out typhoid conjugate vaccines in endemic countries. This will not only reduce the burden of typhoid, but also aid in interrupting the trend of increasing antimicrobial resistance.

Typhoid in Less Developed Countries: A Major Public Health Concern

“…This is especially true if the total public health benefits of a vaccine have been calculated [68]. In the case of typhoid vaccines, this would include indirect protection of those who have not received the vaccine, a reduction in antibiotic use, and a reduction in the development of antibiotic-resistant organisms [69]. Moreover, limiting health inequities and the moral capital the vaccines generate, decreasing outbreaks and the health care delivery distortions, and minimizing economic consequences from the loss of business or tourism when an outbreak occurs are all factors that will reduce the risk of household poverty as a result of the cost of treating typhoid [55,70].…”

Old tools, new applications: use of environmental bacteriophages for typhoid surveillance and evaluating vaccine impact

“…This pathogen is common in many low- and middle-income countries (LMICs) causing an estimated 135 000 deaths and 14 million infections globally (Stanaway et al, 2019). The World Health Organization (WHO) recommended the use of typhoid conjugate vaccines in settings with high burden of typhoid fever (Andrews et al, 2018; Saha et al, 2021). Countries have begun implementing these suggestions, and several countries have performed large-scale clinical trials to demonstrate that these vaccines exhibit 80-85% efficacy in preventing infections (Patel et al, 2021; Qadri et al, 2021; Shakya et al, 2019).…”

Trends in antimicrobial resistance amongstSalmonellaTyphi in Bangladesh: a 24-year retrospective observational study (1999–2022)

“…Multi-drug resistant (MDR, defined as the concurrent resistance to amoxicillin, chloramphenicol, and co-trimoxazole) Salmonella Typhi isolates emerged in the 1970s. 12, 13 This led to ciprofloxacin as the primary treatment choice by mid-1980s, but resistance followed. By mid-2010s, over 90% of Salmonella Typhi in South Asia showed non-susceptibility to ciprofloxacin.…”

“…21 This highlights the looming threat of AMR and related financial burden on patients and healthcare systems which is struggling to cope with high typhoid prevalence in LMICs. 13, 22…”

“…By mid-2010s, over 90% of Salmonella Typhi in South Asia showed non-susceptibility to ciprofloxacin. 14 The current treatments include azithromycin and third-generation cephalosporins such as ceftriaxone, 13 but, reports of resistance to both drugs are increasing. [15][16][17][18][19][20] The 2016 typhoid outbreak in Pakistan, caused by an extensively drug resistant (XDR; resistant to ceftriaxone, ciprofloxacin and firstline of antimicrobials) lineage, 19 sparked global concern.…”