Defining travel-associated cases of enteric fever

Abstract

There is no internationally recognized case-definition for travel-associated enteric fever in non-endemic countries. This study describes the patterns of case reporting between 2007 and 2011 as travel-associated or not from the surveillance data in England, Wales and Northern Ireland (EWNI), before and after a change in the time component of the case-definition in January 2011. It examines in particular the role of a time frame based on the reported typical incubation period in defining a case of travel-associated enteric fever. The results showed no significant differences in the distribution of cases of enteric fever in regards to the interval between the onset and UK arrival in 2011 compared to 2007-2010 (p=0.98 for typhoid and paratyphoid A); the distribution for paratyphoid B was also similar in both time periods. During 2007-2010, 93% (1730/1853) of all of the cases were classified as travel-associated compared to 94% (448/477) in 2011. This difference was not statistically significant. Changing the time component of the definition of travel-associated enteric fever did not make a significant difference to the proportion of travel-associated cases reported by investigators. Our analysis suggests that time might be subordinate to other considerations when investigators classify a case as travel-associated.

Incubation period of typhoidal salmonellosis: a systematic review and meta-analysis of outbreaks and experimental studies occurring over the last century

“…However, we defined subgroups of similar studies and found their mean incubation period to range from 9.7 days to 21.2 days. These values are within the range quoted by international organisations reporting 3 to 60 days [ 3 ], 3 to 30 days [ 12 ] and also scientific literatures reporting 10 to 20 days [ 18 ]. Some literature report shorter incubation periods than we observed, like Raffatellu et al reporting a median of 5 to 9 days [ 19 ] or 8 to 14 days [ 18 ].…”

“…These values are within the range quoted by international organisations reporting 3 to 60 days [ 3 ], 3 to 30 days [ 12 ] and also scientific literatures reporting 10 to 20 days [ 18 ]. Some literature report shorter incubation periods than we observed, like Raffatellu et al reporting a median of 5 to 9 days [ 19 ] or 8 to 14 days [ 18 ]. We also identified attack rate and vaccination as possible factors that could affect the incubation period distribution.…”

Increasingly limited options for the treatment of enteric fever in travellers returning to England, 2014–2019: a cross-sectional analytical study

“…Where the antimicrobials used to treat the case could be determined, these data were obtained. While PHE's public health guidance recommends that cases be regarded as travel-associated where symptom onset occurs within 28 days of travel [20], for the purposes of this investigation, we regarded travel within 60 days as pertinent to ascertaining the likely geographical source of an isolate. Where cases had no direct travel history but had recent, close contact with a traveller, the case was regarded as associated with that region of travel as a propagated infection.…”

Why the development of effective typhoid control measures requires the use of human challenge studies

“…Prevention of S . Typhi infection among travelers through pre-travel vaccination is fundamental as international travel becomes more accessible and a significant cause of travel-associated illness (Freedman et al, 2014 ). Government and public health authorities are becoming more involved in promoting immunization, personal hygiene education as well as implementing GeoSentinal sites to collect surveillance data including patient demographic characteristics, detailed travel history, vaccination status, and specific typhoid fever disease diagnosis (Leder et al, 2013 ).…”