Canada Communicable Disease Report
Volume: 23 (ACS-1)
1 April 1997

An Advisory Committee Statement (ACS)
Committee to Advise on Tropical Medicine and Travel (CATMAT)

FEVER IN THE INTERNATIONAL TRAVELLER INITIAL ASSESSMENT GUIDELINES

Introduction

1. Initial approach to the diagnosis in the acutely febrile, returning traveller

2. Public-health and quarantine services, and documents related tonternational disease control

Appendix

References

Introduction

Fever is a cardinal sign of disease ^(1,2) , but it is sufficiently non-specific to be of little etiologic or diagnostic assistance on its own. A detailed history, including a complete travel history, and an appropriate physical examination are essential starting points. The judicious use of laboratory testing should follow. These steps are essential in defining the cause of fever in international travellers. It must be emphasized that diagnoses of the tropical causes of fever are likely to be missed, with serious consequences to the patient, if febrile patients are not asked about their travel exposures ^(3,4) . All febrile patients must be asked if they have travelled. If exposed to malaria, they must be assumed to have it, until proven otherwise.

This article addresses two features of fever in the international traveller:

1. the initial approach to the diagnosis in the acutely febrile, returning traveller; and

2. public-health and quarantine services, and documents related to international disease control.

* Members: Dr. W. Bowie; Dr. L.S. Gagnon; Dr. S. Houston; Dr. K. Kain; Dr. D. MacPherson (Chairman); Dr. V. Marchessault; Dr. H. Onyett; Dr. R. Saginur; Dr. D. Scheifele (NACI); Dr. F. Stratton; Mrs. R. Wilson (CUSO).

Ex-Officio Members: LCdr. D. Carpenter (DND); Dr. E. Gadd (HPB); Dr. B. Gushulak (Secretary); Dr. H. Lobel (CDC); Dr. A McCarthy (LCDC and DND); Dr. S. Mohanna (MSB); Dr. M. Tipple (CDC).

1. Initial approach to the diagnosis in the acutely febrile, returning traveller

Although travel raises the possibility of an unusual imported disease in the returning ill traveller, non-tropical diseases such as viral infections, pneumonia, and urinary tract infections remain common. Table 1 presents two lists of causes of fever in returning travellers as diagnosed by tropical medicine clinics. It is important to note that malaria is by far the most frequent tropical cause of fever, accounting for 30% to 40% of causes of fever in returning travellers. Immediate diagnosis must be made and immediate action taken to preserve the health of the individual as well as to protect the community in cases of malaria, meningitis, and the viral causes of hemorrhagic fever. The interested reader is directed to more detailed discussions of the returning ill traveller for additional information ^{( 5-8)} .

Table 1 Reported causes of fever in returning travellers

The approach to fever in the traveller must begin with a detailed travel history, which includes departure and arrival dates, countries visited, nature of exposure abroad, pre-exposure vaccinations, and the use of antimalarial drugs and other antimicrobials. A knowledge of incubation periods, and global distribution and mode of transmission of tropical diseases will assist in forming a differential diagnosis. There are several published resources which detail the global distribution of diseases ^(9-11) . In addition, there are frequently updated epidemiologic reports on specific diseases, such as malaria ^(12-16) , polio^(17-19) , and tuberculosis ^(20-21) . Table 2 presents typical incubation periods for common tropical diseases.

In a recent prospective survey of fever in 1,572 volunteer travellers, 123 of 1,187 (10.4%) travellers who returned their surveys reported having had fever ⁽²²⁾ . In the majority of patients, malaria was not considered as a possible diagnosis by travellers themselves. Only six of these 123 travellers treated themselves for presumptive malaria. An extensive evaluation of the cause of fever in these six travellers resulted in the following diagnoses: three viral infections (one dengue), one gastritis, one amebiasis, and one malaria (species not stated). An additional 14.2% of travellers were ill or had an accident, but had no fever. The remaining 73.5% reported no illness at all during their travels or during the 1 month following return. Fevers are common in travellers but are rarely acted upon as potentially serious illnesses. Improved pre-travel counselling on the implications of fever during or following international travel is needed to reduce delays in seeking medical assistance and to increase the awareness of tropical diseases in travellers.

Table 2 Incubation periods for selected tropical infections ⁽³³⁾

The physical examination must address two questions.

1. Is there an obvious source or cause for the fever?

2. Are there any manifestations of sepsis, shock or hemorrhage?

Clinical findings may assist in defining the most probable cause of fever in the international traveller, although laboratory testing is usually required to confirm the diagnosis. For example, the presence of a tick eschar points to typhus, rose spots to typhoid fever, and jaundice to hepatitis.

The initial laboratory investigations (Table 3) should be directed toward the most probable cause of fever. Malaria films must be performed and competently examined as a matter of urgency, if the patient has travelled through a malarious zone. If blood films can not be examined quickly and competently, the films or the patient should be referred as quickly as possible to a centre where this can be done ⁽²³⁾ . The urgency in examining blood films is independent of whether the patient has used antimalarial chemosuppressive therapy or not. The greatest risk period for clinical presentation of Plasmodium falciparum infections is in the 12 weeks following the last, potential, infected-mosquito exposure. Blood films may need to be repeated even if the first ones are negative.

Table 3 List of initial laboratory investigations for fever in the returning traveller

Features of sepsis, shock or hemorrhage raise concerns of bacterial sepsis (e.g. enteric fever, meningococcemia), severe and complicated malaria, and viral hemorrhagic fevers (e.g. severe dengue, Ebola, Lassa, etc.). Cultures of blood, urine, and possibly cerebral spinal fluid must be performed. Presumptive therapy should be considered for severe or life-threatening infections. If diagnostic or treatment difficulties arise, consultation with an expert in tropical medicine or infectious diseases should be sought as soon as possible.

Practice Point
Diagnosis must begin with a detailed travel history. The febrile traveller, who was exposed to malaria, has malaria until proven otherwise.

Recommendation 1
All assessments of febrile patients should include a travel and exposure history. Once a history of travel is obtained, a complete assessment of its relevance to the febrile event is required.

Category A⁽²⁴⁾
Good evidence to support a recommendation for use.

Grade III
Evidence from opinions of respected authorities on the basis of clinical experience, descriptive studies, or reports of expert committees.

2. Public-health and quarantine services, and documents related to international disease control

Local, provincial, and federal public-health and quarantine services are responsible for surveillance, detection, and interventions to protect Canadians against communicable diseases. Recent events, such as international outbreaks of plague in India ⁽²⁵⁾ , Ebola virus in Zaire ⁽²⁶⁾ , and dengue throughout the tropics ⁽²⁷⁾ , have raised the profile of these services.

Questions related to international health and the potential scenario of an unusual, imported, dangerous disease are now addressed in detailed documents. These documents on the management of suspected cases of virulent infectious diseases recognize that surveillance is the weakest link in the defence against the importation of emerging and re-emerging infectious diseases ^(28-30) . Rapid international travel can permit even communicable infectious diseases with short incubation periods to bypass several international borders before their clinical manifestation. By the time patients present to medical attention, they may be far from the epicentre of disease activity and an early correct diagnosis may be problematic. The new frontier for presentation of imported communicable diseases is likely to be the emergency room or a primary caregiver's office, and it could be anywhere in the country.

The use of policy documents to control the importation of virulent communicable diseases is likely to have very limited success unless accompanied by the ability to:

• put practical practice guidelines into the hands of primary caregivers throughout the country, and

• communicate when a new potentially "importable" disease has appeared.

This has implications for international disease surveillance and management as well as for local emerging diseases, such as those caused by hantaviruses, multiple-drug resistant organisms (e.g. Mycobacterium tuberculosis, Streptococcus pneumoniae, vancomycin-resistant Enterococcus), and virulent disease syndromes (e.g. Group A streptococcal disease, toxic-shock syndrome, Lyme disease), which may have significant public-health impacts as well. Accurate and timely reporting to the health-care delivery site will be the challenge for the foreseeable future. The appendix contains the addresses of the provincial and federal contacts for questions related to public- and quarantine-health issues.

Practice Point
Rapid international travel has allowed the possibility of exotic and emerging infectious diseases to be acquired in one locality and then to present clinically thousands of miles away. A high degree of suspicion must be maintained and contact made with a tropical medicine or infectious disease expert, medical officer of health, or the federal health department when clinical questions arise.

Recommendation 2

1. Practical practice guidelines should be made available to primary health-care givers to assist in the assessment of emerging and re-emerging communicable infectious diseases.

2. Communications systems should be developed that will permit notification of these diseases and other relevant information to be rapidly and accurately conveyed throughout the health-care system.

Category A
Good evidence to support a recommendation for use.

Grade III
Evidence from opinions of respected authorities on the basis of clinical experience, descriptive studies, or reports of expert committees.

Appendix

Provincial and Federal Contacts for Questions Related to Public- and Quarantine-Health Issues

References

1. Wunderlich CA. On the temperature in diseases: a manual of medical thermometry. London: the New Syndenham Society, 1871.

2. Rodbard D. The role of regional body temperature in the pathogenesis of disease. N Engl J Med 1981;305:808-14.

3. Wittes RC, Constantinidis P, McLean JD et al. Recent Canadian deaths from malaria acquired in Africa. CDWR 1989;40:199-204.

4. Sharma S, Humar A, Kain KC et al. Fatal falciparum malaria in Canadian travellers. CCDR 1996;22:165-68.

5. Wise M, Walter A. Fever in the returning traveller. Diagnosis 1986 (May);8:30-41.

6. Hill DH. Evaluation of the returned traveller. Yale J Biol Med 1992;65:343-56.

7. Strickland GT. Fever in the returned traveller. Med Clin North Am 1992;76:1375-92.

8. Humar A, Keystone J. Evaluating fever in travellers returning from tropical countries. BMJ 1996;312:953-56.

9. Wilson ME. A world guide to infections. Oxford: Oxford University Press, 1991.

10. Stuerchler D. Endemic areas of tropical infections. Kirkland, WA: Hogrefe & Huber, Publishers, 1988.

11. Lambert G. Guide d'intervention santé-voyage. Situation épidémiologique et recommandations 1994. Montréal, QC : Gouvernement du Québec, Ministère de la Santé et des Services sociaux, 1995.

12. World Health Organization. World malaria situation in 1993. WHO Wkly Epidemiol Rec 1996;71:17-22.

13. Ibid:25-9.

14. Ibid:37-9.

15. Ibid:41-8.

16. Committee to Advise on Tropical Medicine and Travel. Canadian recommendations for the prevention and treatment of malaria among international travellers. CCDR 1995;21S3:1-18.

17. World Health Organization. Expanded programme on immunization - progress towards the global elimination of poliomyelitis. WHO Wkly Epidemiol Rec 1996;71:189-94.

18. Idem. Expanded programme on immunization - certification of poliomyelitis eradication - the Americas. WHO Wkly Epidemiol Rec 1994;69:293-95.

19. Committee to Advise on Tropical Medicine and Travel. Polio immunization for international travel. CCDR 1995;21:145-48.

20. Idem. Tuberculosis screening and the international traveller. CCDR 1996;22:149-55.

21. World Health Organization. Tuberculosis. WHO Wkly Epidemiol Rec 1996;71:65-69.

22. Schlagenhauf P, Steffen R, Tschopp A et al. Behavioural aspects of travellers in their use of malaria presumptive treatment. Bull World Health Organization 1995;73:215-21.

23. Palmer J, Thomson S. Parasitology. Broadsheet #13: recommendations for examination of blood films for malaria parasites. Laboratory Proficiency Testing Program 1996 July;3(4.3):8-11.

24. MacPherson DW. Evidence-based medicine. CCDR 1994;20:145-47.

25. World Health Organization. Plague, India. WHO Wkly Epidemiol Rec 1994;69:289-91.

26. Idem. Ebola haemorrhagic fever, Zaire. Ibid:137.

27. Idem. Dengue and dengue haemorrhagic fever, 1990-1994, Singapore. Ibid:334-35.

28. Idem. Viral haemorrhagic fever - management of suspected cases. Ibid:249-56.

29. LCDC. Canadian contigency plan for viral hemorrhagic fevers and other related diseases. CCDR 1997;23S1:1-13.

30. United States National Science and Technology Council. Committee on International Science, Engineering, and Technology. Working Group on Emerging and Re-emerging Infectious Diseases. Infectious disease - a global threat. Washington, D.C.: United States National Science and Technology Council, 1995.

31. MacLean JD, Lalonde RG, Ward B. Fever from the tropics. Travel Med Advisor 1994 (May):27.1-27.14.

32. Doherty JR, Grant AD, Bryceson ADM. Fever as the presenting complaint in travellers returning from the tropics. Q J Med 1995;88:277-81.

33. Benenson AS, ed. Control of Communicable Diseases Manual. 16^th ed. Washington, D.C.: American Public Health Association, 1995.

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