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Infectious Disease > Infections in the Returning Traveller > Flashcards

Infections in the Returning Traveller Flashcards

1
Q

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

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

A

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

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2
Q

Fever in the returning traveller

A
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3
Q

Geographical summary of returning traveller conditions:

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

A

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

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4
Q

How do patients with fever present?

A
  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)
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5
Q

Key points in history for travellers

A

Travel Hx – within last 3 months

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

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6
Q

Key points in examination for returning travellers

A

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

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7
Q

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

A
  • 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?
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8
Q

Incubation periods for infectious diseases - short <10days

A

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

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9
Q

Incubation periods for infectious diseases - medium 11-21 days

A

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

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10
Q

Incubation periods for infectious diseases - long >21days

A

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

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11
Q

The Neutrophil Count – acute fevers

A
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12
Q

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

A

Malaria and Dengue unlikely with a normal platelet count

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13
Q

Low platelet counts common in what infections?

A

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

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14
Q

Is CRP high or low in pyogenic infections?

A

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

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15
Q

Malaria is caused by …

A

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

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16
Q

Most common malaria parasite?

A

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

17
Q

Malarial Species in Humans
Genus and Species

A

Genus species
Plasmodium falciparum *
vivax
ovale
malariae
knowlesi

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

18
Q

Malaria - History

A

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

19
Q

Falciparum malaria

A

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

20
Q

Uncomplicated malaria

A

Examination: Fever
Splenomegaly

No rash, pharyngitis or lymphadenopathy

•Investigations: Thrombocytopenia
Normal WBC (lymphopenia)
± Anaemia

21
Q

Examination: Fever
Splenomegaly

No rash, pharyngitis or lymphadenopathy

•Investigations: Thrombocytopenia
Normal WBC (lymphopenia)
± Anaemia

A

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%.

22
Q

In a patient with suspected malaria, consider 3 things

A

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

23
Q

Enteric fever - Salmonella paratyphi A isolated from blood cultures

Treatment?

A

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

24
Q

Overview of enteric fever

A

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.

25
Q

The incubation period of typhoid and paratyphoid infections is…

A

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

26
Q

The clinical presentation of … is often confused with malaria

A

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

27
Q

Diagnosing typhoid fever

A

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 !!

28
Q

Enteric Fever

A

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

29
Q

Symptoms of enteric fever

A

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%

30
Q

Enteric fever examination signs

A

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

31
Q

Diagnosis of enteric fever

A

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

32
Q

Treatment for enteric fever

A

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

33
Q

Compilations of enteric fever in weeks 3-4

A

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

34
Q

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

A

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

35
Q

Key notes on arboviruses

A

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

36
Q

‘Emerging’ new and old infections

A

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….

37
Q

Summary of infectious diseases in returning traveller:

A

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

Infectious Disease (21 decks)

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