From the Guidelines
Reinfection and relapse in enteric fever are distinct clinical scenarios, with reinfection occurring when a patient acquires a new infection from an external source, and relapse happening when the same infection returns after apparent recovery, typically within 2-3 weeks of completing treatment. The key difference between the two lies in their underlying causes and implications for management. Reinfection is often associated with exposure to contaminated food or water sources, whereas relapse may indicate inadequate initial treatment or deep-seated foci of infection 1.
Clinical Presentation and Diagnosis
To distinguish between reinfection and relapse, consider the following factors:
- Timing: Relapses tend to occur sooner after treatment, usually within 2-3 weeks 1.
- Strain typing: If available, this can help determine whether the infection is a new strain (reinfection) or the same strain (relapse) 1.
- Epidemiological context: Exposure to new sources of infection suggests reinfection, while the absence of such exposure may indicate relapse 1.
Treatment Approaches
For relapse, it is recommended to use a different antibiotic than the initial regimen, such as:
- Azithromycin 1g on day 1 followed by 500mg daily for 6 days 1.
- Ceftriaxone 2g IV daily for 10-14 days 1. For reinfection, standard first-line therapy is appropriate, including fluoroquinolones like ciprofloxacin 500mg twice daily for 10 days, if susceptibility is confirmed 1.
Management Considerations
Both conditions require:
- Blood cultures before starting antibiotics 1.
- Adequate hydration and fever management 1.
- Monitoring for complications, such as gastrointestinal bleeding, intestinal perforation, and typhoid encephalopathy 1. The distinction between reinfection and relapse matters because it informs the approach to treatment and public health intervention, with relapse suggesting a need to review initial treatment strategies and reinfection highlighting the importance of addressing ongoing exposure to contaminated sources 1.
From the Research
Definition of Reinfection and Relapse
- Reinfection refers to a new infection with a different strain of the bacteria, whereas relapse refers to the recurrence of the same infection [ 2 ].
- Relapse can occur due to various factors such as incomplete treatment, antibiotic resistance, or re-exposure to the bacteria [ 2 ].
Factors Contributing to Relapse
- Delayed treatment initiation and longer time to defervescence after treatment initiation can increase the risk of relapse [ 2 ].
- The use of certain antibiotics, such as ceftriaxone, may also contribute to a higher risk of relapse if not used for an adequate duration [ 2 ].
Treatment and Relapse
- The choice of antibiotic and treatment duration can impact the risk of relapse [ 3, 4, 2 ].
- Some studies suggest that combination therapy, such as ceftriaxone and levofloxacin, may be effective in reducing the risk of relapse [ 5 ].