Personal Practice

Infection in migrantsandrew riordan

Abstractchildren who present with fever after travelling to the tropics may have

a cosmopolitan infection (one commonly seen in the UK, e.g. Uti), an

imported infection (not normally seen in the UK, e.g. malaria) or both.

a treatable cause of fever was identified in 46% children presenting to

hospital with fever after returning from the tropics. Diarrhoea malaria

and respiratory infections were the commonest diagnoses. Febrile chil-

dren who have travelled to the tropics in the preceding year should

have; full blood count, blood film for malarial parasites, stool culture

and chest X-ray. For children who have travelled in the preceding month,

a blood culture should also be taken.

Keywords malaria; tropical infection

Introduction

Children can travel from the tropics within the incubation period for most infections. They may present with ‘tropical’ infections that their local paediatrician may not expect or recognise. This article will focus on infections in children presenting with fever after travelling from the tropics.

History

A detailed travel history should be taken from all children pre-senting with fever.

Where have you been?The likely infections vary with the destination visited.1 Malaria is one of the most common causes of fever among travellers from every tropical region. Dengue fever is a common cause in travel-lers from all regions, except Africa, whilst enteric fever occurs mostly in travellers from South Asia.1

Children mostly travel to visit friends and relatives in their parents’ country of origin. Most of the UK population born in tropical areas come from the Indian subcontinent or Africa. British children are thus likely to visit these tropical areas and are at risk of malaria and enteric fever.

When did you become ill?The timing of travel, together with the known incubation peri-ods of different illnesses, may help to identify or exclude spe-cific infections. Enteric fever mostly presents within 1 month of

Andrew Riordan MD FRCPCH DTM&H is Consultant in Paediatric

Immunology and Infectious Diseases, Royal Liverpool Children’s

Hospital, Liverpool, UK.

PaeDiatrics anD cHilD HealtH 18:11 51

arrival. Plasmodium falciparum malaria mostly presents within 1 month, whereas P. ovale and P. vivax infections can present up to 1 year after travel.2 Tuberculosis in children born abroad mostly occurs within 5 years of arrival in the UK.3

What have you been doing?Asking about dietary habits may be helpful, for example brucello-sis should be considered if the child has drunk unpasteurised milk in the Middle East or southern Europe. Hospital admission while overseas, especially transfusions, carries a risk of blood-borne infection including human immunodeficiency virus, hepatitis and malaria. Asking about exposure to local outbreaks of illness while abroad or recent illness in family/contacts may also be helpful.

What preventative measures did you take?Travel vaccines and malaria prophylaxisChildren travelling to, or who have recently arrived from, the tropics often do not take preventative measures. Malaria prophy-laxis is taken by only 3–15% of children with imported malaria4 and few children receive pre-travel vaccinations.5

Children visiting their parents’ home country rarely seek pre-travel advice. Parents may falsely assume that their children are protected from tropical diseases, because of previous time spent in endemic areas or because of their ethnic origin.6

Routine immunisationsMany children born abroad are likely to be immunised against diphtheria, tetanus, pertussis, polio and tuberculosis in the first year of life and measles in the second year of life. Increasing numbers are also receiving Haemophilus influenzae type b (Hib) vaccine. Some children will not have had Hib and none will have had measles-mumps-rubella (MMR), pneumococcal or meningo-coccal C vaccines.

Children arriving from areas of chronic conflict may not have been immunised and are, thus, at risk of vaccine preventable disease, such as measles or diphtheria.

Localising symptoms

DiarrhoeaDiarrhoea is one of the most common illnesses to affect people who travel to the tropics.7 Young children have the highest risk of getting diarrhoea and the clinical course in infants may be severe and protracted.8

However, other infections such as malaria, enteric fever or pneumonia can present with fever and diarrhoea and these should always be considered.

RashA maculopapular rash with fever may be due to dengue fever, but a non-blanching rash may indicate meningococcal disease, rickettsial infection or (rarely) viral haemorrhagic fever. Patients with African tick typhus and scrub typhus (Asia) often have an eschar (black scab) at the site of the infecting tick bite.

Periodicity of feverThe characteristic patterns of fever associated with malaria are seen in less than 25% of paediatric cases.4 This feature is, there-fore, unreliable for predicting imported malaria in children.

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Examination

Children should be examined for the features of ‘serious infec-tion’ described in the National Institute for Clinical Excellence (NICE) ‘Feverish illness in children’ guideline.9 Examination may reveal a focus of infection, although this is uncommon in most ‘tropical’ infections.

The most helpful clinical findings are hepatomegaly, sple-nomegaly and jaundice. These can be found in children with malaria, hepatitis and enteric fever.5 However, the absence of these features does not exclude malaria or other illnesses, since splenomegaly is found in only 48% of children with imported malaria and hepatomegaly in 56%.4

The combination of jaundice and fever is uncommon in chil-dren with acute viral hepatitis. Children with this combination should be investigated to exclude malaria, enteric fever, glandu-lar fever or leptospirosis. Children with enteric fever rarely have a relative bradycardia.10

Case series of febrile children admitted to hospital after returning from the tropics*

Cause of fever Birmingham5

(n = 153)

Birmingham13

(n = 45)

London14

(n = 31)

TropicalMalaria

P. vivax 19 10 1

P. falciparum 3 3 3

Diarrhoea

travellers 15 6 0

Bacterial 16 3 3

Giardiasis 5 1 0

cryptosporidium 2 1 0

Hepatitis 8 6 1

Dengue 0 0 2

enteric fever 5 1 2

tuberculosis 2

ricketsial infection 1

Cosmopolitanrespiratory infection

lower 18 7 2

Upper 5 6 1

Uti 6 1

cellulitis/lymphadenitis 3 2 1

Measles 1

Viral gastroenteritis 4

Meningococcal disease 2

no diagnosis 52 3 14

Other Kawasaki 1 sle 1 aMl 1

*some children had more than one infection. P. vivax, Plasmodium vivax; P. falciparum, Plasmodium falciparum; Uti, urinary tract infection; sle, systemic lupus erythematosus; aMl, acute myeloid leukaemia.

Table 1

PaeDiatrics anD cHilD HealtH 18:11 52

Investigations

Children should be investigated as described in the NICE guide-line.9 In addition, febrile children who have travelled to the tropics in the preceding year should have the following investi-gations: full blood count, blood film for malarial parasites, stool culture and chest x-ray.5 For children who have travelled in the preceding month, a blood culture for enteric fever should also be taken.11 Other investigations should be done as clinically indi-cated (e.g. liver function tests).

The diagnosis of malaria is made by examination of thick and thin blood films. Thick blood films are more sensitive, while thin films help to confirm the malaria species. Children with sus-pected malaria, who have a negative blood film, should have at least two repeat blood films, since the initial blood film may be negative in up to 7% of cases.12

Thrombocytopenia is often present in those with malaria. A platelet count above 190 × 109/l is a useful predictor of the absence of malaria in febrile children who have returned from a malaria endemic area (negative predictive value 97%).5 White cell count haemoglobin, neutrophil and eosinophil counts are not helpful.

Cosmopolitan infections

Cosmopolitan infections (such as respiratory or urinary tract infections) are as common as tropical infections in children admitted with fever after travel. About 20% of children have both cosmopolitan and tropical infections.13 Table 1 details the diagnoses of some case series of febrile children admitted to hospital after returning from the tropics.5,13,14 ◆

REfEREnCEs

1 Freedman Do, Weld lH, Kozarsky Pe, et al. Geosentinel surveillance

network. spectrum of disease and relation to place of exposure

among ill returned travelers. N Engl J Med 2006; 354: 119–130.

2 Brabin BJ, Ganley Y. imported malaria in children in the UK. Arch Dis

Child 1997; 77: 76–81.

3 teo sss, alfaham M, clark J, et al. British paediatric surveillance unit

childhood tuberculosis study. Arch Dis Child 2006; 91(suppl i): a2.

4 ladhani s, aibara rJ, riordan Fa, shingadia D. imported malaria

in children: a review of clinical studies. Lancet Infect Dis 2007; 7:

349–357.

5 West ns, riordan Fa. Fever in returned travellers: a prospective

review of hospital admissions for a 2 1/2 year period. Arch Dis Child

2003; 88: 432–434.

6 Bradley D, Warhurst D, Blaze M, smith V. Malaria imported into the

United Kingdom in 1992 and 1993. Commun Dis Rep CDR Rev 1994;

4: r169–172.

7 consensus conference. traveller’s diarrhea. JAMA 1985; 253: 2700–2704.

8 Pitzinger B, steffen r, tschopp a. incidence and clinical features of

traveller’s diarrhea in infants and children. Pediatr Infect Dis J 1991;

10: 719–723.

9 national institute for clinical excellence. Feverish illness in children.

london: nice, 2007.

10 Davis tM, Makepeace ae, Dallimore ea, choo Ke. relative

bradycardia is not a feature of enteric fever in children. Clin Infect

Dis 1999; 28: 582–586.

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Personal Practice

11 shingadia D, al-ansari H, novelli V. investigation and diagnosis of

fever in the returning traveller. Curr Paediatr 1996; 6: 108–113.

12 ansdell Ve, Boosey cM, Geddes aM, Morgan HV. Malaria in

Birmingham 1968–73. BMJ 1974; 2: 206–208.

13 riordan Fa. children should be investigated for malaria. BMJ 1998;

317: 1390.

14 Klein Jl, Millman Gc. Prospective, hospital based study of fever in

children in the United Kingdom who had recently spent time in the

tropics. BMJ 1998; 316: 1425–1426.

Practice points

• about 50% of all children returning from the tropics who present

to hospital with fever have a condition that needs treatment

PaeDiatrics anD cHilD HealtH 18:11 52

• common imported infections in children are: malaria,

diarrhoea, hepatitis and enteric fever

• cosmopolitan infections (such as respiratory or urinary tract

infections) are as common as tropical infections. about 20%

of children have both cosmopolitan and tropical infections

• Febrile children who have travelled to the tropics in the

preceding year should have: full blood count, blood film for

malarial parasites, stool culture and chest x-ray. For children

who have travelled in the preceding month, a blood culture

for enteric fever should also be taken

• Key questions to answer include:

- is it malaria (+/− another infection)?

- if not, is it ‘tropical’, ‘cosmopolitan’ or both?

- does it need treating?

1 © 2008 elsevier ltd. all rights reserved.