Infections in the Returning Traveller

Question 1

What is the commonest cause of death among travellers in the tropics?

• Cardiovascular disease
•Drowning
•Influenza
•Malaria
•Road traffic accidents

Answer 1

->Cardiovascular disease
•Drowning
•Influenza
•Malaria
•Road traffic accidents

Question 2

Fever in the returning traveller

Answer 2

Question 3

Geographical summary of returning traveller conditions:

Malaria – predominantly …
Dengue – mainly …
Enteric fever – mainly …
Rickettsial diseases – mainly …

Answer 3

Malaria – predominantly Sub-Saharan Africa
Dengue – mainly SE Asia and Caribbean
Enteric fever – mainly SC Asia
Rickettsial diseases – mainly SS Africa

Question 4

How do patients with fever present?

Answer 4

1. New onset symptomatic pyrexia as primary presenting feature
   - Hot, cold, drenching sweats, rigors, headache
   NB ~50% self-limiting, no cause identified
2. Fever as a clinical sign accompanying another presenting complaint e.g. Diarrhoea, Dyspnoea, Abdominal pain
3. PUO
4. Overt or evolving sepsis (SIRS)

Question 5

Key points in history for travellers

Answer 5

Travel Hx – within last 3 months

Where? Precisely.. rural vs urban
When? Incubation periods – Exposure Interval
What? Exposures
Prophylaxis?
Antimalarials
Vaccination
‘Prophylactics’

Question 6

Key points in examination for returning travellers

Answer 6

Well or unwell
Localising or non-localising features
Rash
Pharyngitis
Jaundice
Lymphadenopathy
Hepatosplenomegaly
EXAMINE THE WHOLE PATIENT

Question 7

The Differential Diagnosis – key questions and simple clues for the returning traveller

Answer 7

• Geography
  •Time of onset in relation to exposure – is this compatible with the incubation period?
  •Duration of fever (acute vs chronic)
  •What is the WBC?
  •What is the PLT count?
  •What is the CRP?

Question 8

Incubation periods for infectious diseases - short <10days

Answer 8

Malaria (P. falciparum)
Enteric bacteria
Pneumonia
Dengue and other arboviral infections
Rickettsial infections
Viral haem. fever
Plague
Influenza
Anthrax

Question 9

Incubation periods for infectious diseases - medium 11-21 days

Answer 9

Malaria (P. falciparum)
Typhoid
Strongyloides
Leptospirosis
Rickettsial infections
Brucellosis
Lyme disease
Cutaneous myiasis
scrub typhus, spotted fevers and Q fever

Question 10

Incubation periods for infectious diseases - long >21days

Answer 10

Malaria
Amoebic liver abscess
Viral hepatitis
Tuberculosis
Enteric protozoa
Enteric helminths
HIV
Schistosomiasis
Leishmaniasis

Question 11

The Neutrophil Count – acute fevers

Answer 11

Question 12

If platelet count is NORMAL, what infections are less likely? (2)

Answer 12

Malaria and Dengue unlikely with a normal platelet count

Question 13

Low platelet counts common in what infections?

Answer 13

• Dengue
• Enteric fever
• HIV seroconversion
• Malaria
• Sepsis
• Other viral infections

Question 14

Is CRP high or low in pyogenic infections?

Answer 14

High in Phoenician infections
Often elevated in malaria
Usually <70 in viral infections

Question 15

Malaria is caused by …

Answer 15

Malaria is caused by protozoan parasites of the genus Plasmodium and is transmitted to humans through the bite of female Anopheles spp. mosquitoes.

Question 16

Most common malaria parasite?

Answer 16

There are five species of Plasmodium that regularly cause disease in humans: P. falciparum, P. vivax, P. malariae, P. ovale and P. knowlesi. P. falciparum is the most common malaria parasite on the African continent and in the World Health Organization (WHO) regions of South East Asia, the eastern Mediterranean and Western Pacific [1,2]. This parasite is responsible for the most severe form of malaria and the most deaths

Question 17

Malarial Species in Humans
Genus and Species

Answer 17

Genus species
Plasmodium falciparum *
vivax
ovale
malariae
knowlesi

P. falciparum malaria is the most common presenting in UKmost serious

Question 18

Malaria - History

Answer 18

Prodromal aches and fatigue
Fever + rigors
Flu - like illness/myalgia
Cough
Diarrhoea
Jaundice

Question 19

Falciparum malaria

Answer 19

80% have symptoms within a month
60% no prophylaxis
Only 20% fully compliant with recommended regimen
10% mortality

Question 20

Uncomplicated malaria

Answer 20

Examination: Fever
Splenomegaly

No rash, pharyngitis or lymphadenopathy

•Investigations: Thrombocytopenia
Normal WBC (lymphopenia)
± Anaemia

Question 21

Examination: Fever
Splenomegaly

No rash, pharyngitis or lymphadenopathy

•Investigations: Thrombocytopenia
Normal WBC (lymphopenia)
± Anaemia

Answer 21

Impaired consciousness or seizures.
● Renal impairment
●Acidosis (pH < 7.3).
● Hypoglycemia
●Pulmonary oedema or acute respiratory distress syndrome (ARDS).
● Haemoglobin 80 g/L.
● Spontaneous bleeding/disseminated intravascular coagulation.
● Shock (BP < 90/60 mmHg).
● Haemoglobinuria (without G6PD deficiency).
● Parasitaemia >10%.

Question 22

In a patient with suspected malaria, consider 3 things

Answer 22

Has the patient got malaria?
Is it falciparum or one of the others?
Uncomplicated malaria or severe?

Question 23

Enteric fever - Salmonella paratyphi A isolated from blood cultures

Treatment?

Answer 23

Treated with ceftriaxone iv 10-14 days
Notified to public health

Question 24

Overview of enteric fever

Answer 24

Salmonella enterica serotypes Typhi and Paratyphi A, Paratyphi B, and Paratyphi C cause potentially severe and occasionally life-threatening bacteremic illnesses referred to respectively as typhoid and paratyphoid fever, and collectively as enteric fever

Humans are the only source of these bacteria; no animal or environmental reservoirs have been identified. Typhoid and paratyphoid fever are acquired through consumption of water or food contaminated by feces of an acutely infected or convalescent person or a chronic, asymptomatic carrier.

Transmission through sexual contact, especially among men who have sex with men, has been documented rarely.

Question 25

The incubation period of typhoid and paratyphoid infections is…

Answer 25

The incubation period of typhoid and paratyphoid infections is 6–30 days.

Question 26

The clinical presentation of … is often confused with malaria

Answer 26

The clinical presentation is often confused with malaria, and typhoid fever should be suspected in a person with a history of travel to an endemic area who is not responding to antimalarial medication

Question 27

Diagnosing typhoid fever

Answer 27

Patients with typhoid or paratyphoid fever have bacteremia. Blood culture is the mainstay of diagnosis in typhoid and paratyphoid fever; however, a single culture is positive in only approximately 50% of cases. Multiple cultures increase the sensitivity and may be required to make the diagnosis. Bone marrow culture increases the diagnostic yield to approximately 80% of cases and is relatively unaffected by previous or concurrent antibiotic use. Stool culture is not usually positive during the first week of illness, so blood culture is preferred. Urine culture has a lower diagnostic yield than stool culture for acute cases. Clinical diagnosis !!

Question 28

Enteric Fever

Answer 28

Clinical syndrome caused by Salmonella Typhi (typhoid fever) Or S. Paratyphi (paratyphoid fever) Faeco-oral spread through contaminated water or food Incubations period 5-21 days (intracellular pathogen) Humans only reservoir

Question 29

Symptoms of enteric fever

Answer 29

Diarrhoea initially (NB not always) Fever Abdominal symptoms Constipation (up to 40%) , pain (20-40%) Non-specific symptoms Headache, lethargy, cough, anorexia, dizziness, myalgia Neuropsychiatric Confusion, delirium 5-10%

Question 30

Enteric fever examination signs

Answer 30

Fever Patient appears unwell Rose spots (30%) Chest signs Abdominal pain Hepatosplenomegaly

Question 31

Diagnosis of enteric fever

Answer 31

Lymphopenia Thrombocytopenia occasionally Mildly deranged LFTs Definitive diagnosis involves culture: Blood, urine, rose spots, faeces, bone marrow Blood cultures only 50-70% sensitivity - repeat For some people it is a clinical diagnosis due to difficulty in diagnosing

Question 32

Treatment for enteric fever

Answer 32

General supportive Fluids, antipyretic, analgesia Resistance an increasing problem: chloramphenicol->quinolones->ceftriaxone->may require meropenem

Question 33

Compilations of enteric fever in weeks 3-4

Answer 33

Intestinal perforation Intestinal haemorrhage Cholecystitis Rarely disseminated infection Abscess, endocarditis, pericarditis

Question 34

Key facts on Viral haemorrhagic fevers (‘Rural Africa Risks’)

Answer 34

Lassa Fever Ebola Marburg Haemorrhagic fever Crimean Congo Haemorrhagic fever Esp. rural W. Africa Exposure to rats, bats, funerals, healthcare facilities Incubation period up to 3/52 Infection control / sample handling implications (patient isolation –universal precautions, alert lab, minimum samples, double bag, deliver by hand rather than vacuum

Question 35

Key notes on arboviruses

Answer 35

Viruses transmitted by mosquitoes, ticks or other arthropods Collection of disparate viruses; examples include Dengue, Zika, yellow fever and Chikungunya Most circulate within animal or bird reservoirs Commonly: Short incubation period Fever Low plateletsSyndrome may be fever + Rash Neurological disease Arthritis /arthralgia For interest: Zika complications in pregnancy – microcephaly; dengue Antibody-dependent enhancement of infection; yellow fever vaccine adverse effects

Question 36

‘Emerging’ new and old infections

Answer 36

COVID-19 – China then the rest of the world Ebola outbreaks in W. Africa – 2014 and 2018 Wildtype polio outbreaks -2014 Zika virus – S.America, French Polynesia, SE Asia… 2015/16 Novel Coronavirus (MERSCoV) – Saudi Arabia, Qatar since 2012 2009 Swine ’flu’ Chikungunya virus – Caribbean, Indian Ocean, Italy, SE Asia Autochthonous P.vivax transmission in Greece Sandfly fevers (Phlebovirus) – Italy, Middle east….

Question 37

Summary of infectious diseases in returning traveller:

Answer 37

Geographical factors constrain likely diagnoses Detailed travel history is of key importance Knowledge of incubation periods and exposure interval help to define differential diagnosis A febrile returning traveller from a malaria-endemic area has malaria until proven otherwise A normal platelet count means that Malaria or Dengue fever are less likely diagnoses Viruses and intracellular bacteria are often associated with low/normal WBC counts Don’t forget: Acute EBV, Acute HIV seroconversion, ‘Rural Africa Risks’ i.e. VHFs