Infections in the Returning Traveller Flashcards
What is the commonest cause of death among travellers in the tropics?
• Cardiovascular disease
•Drowning
•Influenza
•Malaria
•Road traffic accidents
->Cardiovascular disease
•Drowning
•Influenza
•Malaria
•Road traffic accidents
Fever in the returning traveller
Geographical summary of returning traveller conditions:
Malaria – predominantly …
Dengue – mainly …
Enteric fever – mainly …
Rickettsial diseases – mainly …
Malaria – predominantly Sub-Saharan Africa
Dengue – mainly SE Asia and Caribbean
Enteric fever – mainly SC Asia
Rickettsial diseases – mainly SS Africa
How do patients with fever present?
- New onset symptomatic pyrexia as primary presenting feature
- Hot, cold, drenching sweats, rigors, headache
NB ~50% self-limiting, no cause identified - Fever as a clinical sign accompanying another presenting complaint e.g. Diarrhoea, Dyspnoea, Abdominal pain
- PUO
- Overt or evolving sepsis (SIRS)
Key points in history for travellers
Travel Hx – within last 3 months
Where? Precisely.. rural vs urban
When? Incubation periods – Exposure Interval
What? Exposures
Prophylaxis?
Antimalarials
Vaccination
‘Prophylactics’
Key points in examination for returning travellers
Well or unwell
Localising or non-localising features
Rash
Pharyngitis
Jaundice
Lymphadenopathy
Hepatosplenomegaly
EXAMINE THE WHOLE PATIENT
The Differential Diagnosis – key questions and simple clues for the returning traveller
- 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?
Incubation periods for infectious diseases - short <10days
Malaria (P. falciparum)
Enteric bacteria
Pneumonia
Dengue and other arboviral infections
Rickettsial infections
Viral haem. fever
Plague
Influenza
Anthrax
Incubation periods for infectious diseases - medium 11-21 days
Malaria (P. falciparum)
Typhoid
Strongyloides
Leptospirosis
Rickettsial infections
Brucellosis
Lyme disease
Cutaneous myiasis
scrub typhus, spotted fevers and Q fever
Incubation periods for infectious diseases - long >21days
Malaria
Amoebic liver abscess
Viral hepatitis
Tuberculosis
Enteric protozoa
Enteric helminths
HIV
Schistosomiasis
Leishmaniasis
The Neutrophil Count – acute fevers
If platelet count is NORMAL, what infections are less likely? (2)
Malaria and Dengue unlikely with a normal platelet count
Low platelet counts common in what infections?
• Dengue
• Enteric fever
• HIV seroconversion
• Malaria
• Sepsis
• Other viral infections
Is CRP high or low in pyogenic infections?
High in Phoenician infections
Often elevated in malaria
Usually <70 in viral infections
Malaria is caused by …
Malaria is caused by protozoan parasites of the genus Plasmodium and is transmitted to humans through the bite of female Anopheles spp. mosquitoes.
Most common malaria parasite?
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
Malarial Species in Humans
Genus and Species
Genus species
Plasmodium falciparum *
vivax
ovale
malariae
knowlesi
P. falciparum malaria is the most common presenting in UKmost serious
Malaria - History
Prodromal aches and fatigue
Fever + rigors
Flu - like illness/myalgia
Cough
Diarrhoea
Jaundice
Falciparum malaria
80% have symptoms within a month
60% no prophylaxis
Only 20% fully compliant with recommended regimen
10% mortality
Uncomplicated malaria
Examination: Fever
Splenomegaly
No rash, pharyngitis or lymphadenopathy
•Investigations: Thrombocytopenia
Normal WBC (lymphopenia)
± Anaemia
Examination: Fever
Splenomegaly
No rash, pharyngitis or lymphadenopathy
•Investigations: Thrombocytopenia
Normal WBC (lymphopenia)
± Anaemia
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%.
In a patient with suspected malaria, consider 3 things
Has the patient got malaria?
Is it falciparum or one of the others?
Uncomplicated malaria or severe?
Enteric fever - Salmonella paratyphi A isolated from blood cultures
Treatment?
Treated with ceftriaxone iv 10-14 days
Notified to public health
Overview of enteric fever
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.
The incubation period of typhoid and paratyphoid infections is…
The incubation period of typhoid and paratyphoid infections is 6–30 days.
The clinical presentation of … is often confused with malaria
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
Diagnosing typhoid fever
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 !!
Enteric Fever
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
Symptoms of enteric fever
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%
Enteric fever examination signs
Fever
Patient appears unwell
Rose spots (30%)
Chest signs
Abdominal pain
Hepatosplenomegaly
Diagnosis of enteric fever
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
Treatment for enteric fever
General supportive
Fluids, antipyretic, analgesia
Resistance an increasing problem:
chloramphenicol->quinolones->ceftriaxone->may require meropenem
Compilations of enteric fever in weeks 3-4
Intestinal perforation
Intestinal haemorrhage
Cholecystitis
Rarely disseminated infection
Abscess, endocarditis, pericarditis
Key facts on Viral haemorrhagic fevers
(‘Rural Africa Risks’)
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
Key notes on arboviruses
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
‘Emerging’ new and old infections
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….
Summary of infectious diseases in returning traveller:
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
