This study took place in Brussels, a capital city with a population of 1,300,000 people, which it is home to residents from over 182 different national backgrounds [12], (Brussels Institute for Analysis and Statistics, 2018), and thirty percent of its habitants were born abroad (13). The University centres where our study was carried out, are two significant public institutions, known to treat particularly a large number of immigrant population compared to other local hospitals.
Although enteric fever is a rare occurrence in Belgium, in the era of globalisation and with the accessibility to long distance travel coupled with multicultural societies, the medical community should be more aware of the diagnostic challenges surrounding enteric fever, especially in a traveller returning from countries hyperendemic for enteric fever. It is important to note, that one fourth of our patients acquired enteric fever locally without a history of travel abroad. In addition, our study found that the majority of our patients were originally coming from areas highly endemic to enteric fever. This correlates also with other clinical studies[13], [14] as well as with a recent paediatric study from France[15]. In the city of Brussels, there are over seven travel clinics recognized as international vaccination centres by the WHO. They serve all the citizens intending to travel around the world. However, out of the whole cohort, only one patient had been immunized 18 months before he contracted the disease. None of the patients that had travelled recently was vaccinated, or had received prior education on enteric fever prevention measures. It is noteworthy that Belgium has a social health care system where all classes of the society have equal access and benefit. Based on the findings of our study, we believe that better education and prevention measures should be given to the future travellers particularly to those visiting relatives and friends[16].
Furthermore, the last WHO’s position[17] paper on typhoid, encourages heavily-burdened countries to add a new generation Typhoid Conjugated Vaccine (TCV) to their national vaccination program as more efficient in terms of immunogenicity and duration of protection. Based on these recommendations, younger children starting from the age of six months can benefit from typhoid immunization. Therefore, immunization, coupled with clear education measures on hygiene, safe water and food consumption can be effective on limiting the incidence of enteric fever.
We found that more than the half of our enteric fever affected patients were below 5 years of age (appendix 1), and this correlates with the findings of Sinha et al. [18] although the most recent global estimates [5] showed a peak in the incidence of enteric fever and the highest mortality rates in children aged 5 to 9 years. However, the authors note that in the heavy burdened countries children are the mostly affected compared to a broader age distribution in low incidence regions. Our study overviewed a 16-year period in a city with low incidence rates of enteric fever. Therefore, it is difficult to generalize these age-related findings in different socio-economic contexts.
All our patients fully recovered from their enteric fever episode and there were no fatalities similar to the outcome in other industrialised setting [4], [15], [19], but despite all these favourable elements, and the small sample cohort, we were able to identify serious complications .We found that the majority of our patients came to the emergency room or were examined by a physician in average two-three times before diagnosis or admission. They all were initially diagnosed with viral infection and despite sometimes repeated complementary blood exams, the findings were inconclusive and patients were sent home without an appropriate diagnosis. Similar findings on misdiagnosis were also described earlier [20], [21], and this confirms the diagnostic difficulties the clinician faces confronting enteric fever as one of the most challenging febrile systemic diseases, provided the few alarming clinical symptoms, the very low inflammatory markers and the low sensitivity of blood cultures[22]. A recent review by Mogasale et al. (18) showed that only 61% of true positive Salmonella ser. Typhi cases were detected through blood cultures meaning that even through blood cultures, two out of five enteric fever affected patients were not detected. Although scientific efforts have been done through the years to achieve better diagnostic tools of enteric fever with typhoid rapid tests, data from the last Cochrane review study[23] suggest that the diagnostic tools on better tests have not managed to replace blood cultures and cultures of bone marrow aspirates in the establishment of a diagnosis of enteric fever.
On analysing this cohort, we found that one of the most consistent hematologic features in our patients was the presence of eosinopenia. Thirty-one of our patients were eosinopenic with twenty-one of them having no eosinophils counted during their bacteriaemic phase.
Numerous studies have reached similar conclusions on the predominant presence of this hematologic parameter in patients affected by enteric fever [20], [24], [25] as well as in cases of sepsis[26] [27], as a positive discriminator of the enteric fever diagnosis. In this case series, among all the other hematologic and biochemical parameters analysed, eosinopenia, together with consistent clinical features, is suggestive of enteric fever. That is why, although enteric fever is not the only disease that causes eosinopenia [28], we believe that its presence must raise suspicion of enteric fever in case of prolonged fever. Importantly, we found low inflammatory markers (median CRP: 44 mg/L) for bacteriaemic children which it is an important finding for all the clinicians evaluating febrile children returning from the tropics[29].
We did not have any Multi Drug-Resistant (MDR) strains in this 33-case cohort. However, 20% of the strains were resistant to Ampicillin and Ciprofloxacin. In Belgium, results from the Centre National de Reference de Salmonella et Shigella (CNRSS) show a low resistance to ciprofloxacin of less than 3%. Furthermore, recent data[30], [31] testify to the emergence of Multi-Drug Resistant (MDR) strain which are found to be resistant to ampicillin, chloramphenicol and trimethoprim-sulfamethoxazole as well as the extremely drug-resistant strands (XDR); the Haplo 58 clone Salmonella ser. Typhi [31] known for expressing resistance to the five first line treatments of enteric fever ampicillin, chloramphenicol, trimethoprim-sulfamethoxazole, fluoroquinolones and third-generation cephalosporins. These data are a paradigm of the increasing difficulties in enteric fever treatment and a plea for the implementation of preventive measures.
We could identify from our cohort that all our patients had high grade fever of over 38.1°C; the majority of patients had gastro-intestinal symptoms as is the presentation in other parts of the world[16] albeit sometimes confounded with upper respiratory symptoms such as unproductive cough. We observed that the older patients presented with headaches. This complaint is one of the most commonly found in adults as described by the human challenge study [32]; possibly this symptom could also occur in infants, but would be difficult to identify given the lack of verbal communication at this age.
All our patients fully recovered from their enteric fever episode and there were no fatalities similarly with the outcome in other industrialized settings[33].
Our study may not have the necessary sample size to allow generalisation especially in low living standard countries, that face major health care challenges; i.e., eighty seven percent of our patients were living in a European setting, without confounders of malnutrition, with easy access to health care facilities, and almost all of them were admitted in average for 8 days and had numerous complications. Importantly, eighty percent of our patients had a delay in diagnosis and went unrecognized. We believe that our observations in this case series have a particular added value by demonstrating the clinical features in children with enteric fever, proving also that challenges remain high regardless if we are in Karachi, Kigali or Brussels.
Clinicians should be aware of the diagnosis of enteric fever and its huge potential of causing disease. We report that unspecific clinical and biological findings were misleading and enteric fever diagnosis was delayed in more than three quarters of our cohort patients, which constitutes an importantly high proportion of cases. Blood cultures should be drawn repeatedly at the ER and at the ward independently of their low sensitivity in patients with prolonged fever. Enteric fever should be high on the list of differential diagnoses, especially in the presence of eosinopenia both in the returning traveller as well as in the patient with a prolonged fever particularly in a multicultural society. Lastly, we found that 93% (31/33) of our patients originated from enteric fever endemic areas. It is therefore important to identify the origin of a patient as a risk factor for enteric fever occurrence and properly educate these patients before travelling to their home country.
Our case series has some limitations since, besides having a small sample size, some of the medical records on exposure and recent travel data of our patients were incomplete and we were fully dependent on physician’s records. Lastly, the laboratory data were not exhaustive and homogenous for all the patients.