Travel-Related Infections Flashcards
Why is considering travel history important?
- imported diseases which are rare/unknown in the UK
- different strains of pathogens (antigenically different, so impacts on protection/detection/antibiotic resistance)
- infection prevention (in wards & in lab)
note: patients with febrile illness + travel history should be isolated pending the diagnosis
What is febrile rigor?
Episode of shaking or exaggerated shivering which can occur with a high fever.
What are some important questions to consider regarding travel history?
- preventative measures taken?
- where? (country/region/water bodies)
- when? (timescale of infection)
- how? (direct or via another country)
- accommodation?
- how long? (timescale of infection exposure)
- specific risks e.g. sexual contact
What is the aetiology and transmission method of malaria?
Most common species is Plasmodium falciparum; others include P. vivax, P. ovale, P. malariae
Vector is the female Anopheles mosquito, which is present in the “malaria belt” (tropical regions including Africa, Asia, Middle East, South & Central America)
No case-case spread (excluding cryptic cases e.g. via baggage in airplane terminal, and iatrogenic cases e.g. IV saline cross-infection) therefore there is no need to isolate
What are the typical history and examination findings in malaria patients?
Incubation period = 1-3 weeks+ after bite
S&S:
- headache
- fatigue (mental or physical tiredness)
- malaise (general feeling or being unwell)
- arthralgia (joint pain without swelling or other signs of arthritis)
- myalgia (muscle pain)
- fever, chills, sweating cycling every 3rd (tertian) or 4th (quartan) day
Examination:
- +/- splenomegaly
- coma
- respiratory distress (metabolic acidosis, pulmonary oedema)
What are the investigations and treatment options for malaria?
Investigations:
- blood smear to detect parasites
- FBC, U&Es, LFTs, glucose
- head CT if CNS symptoms are present
Treatment depends on species :
- falciparum: quinine/ortemisinin
- other species: chloroquine +/- primaquine (when in liver)
Outline the life cycle of the malaria parasite.
Parasite in gut of anopheles mosquito enters salivary gland
Infects human host through mosquito bite
Parasite initially enter the liver (exo-erythrocytic phase) and subsequently enter RBCs (erythrocytic phase)
note: some species remain in liver, so malaria symptoms may occur long after infection by the parasite
How can malaria be prevented?
Assess risk = knowledge of areas at risk, especially by regular/returning travellers (including original natives)
Bite prevention = repellant, adequate clothing, nets, chemoprophylaxis
Chemoprophylaxis = specific to region (start before travel and continue after return to cover the incubation period)
What is the aetiology and transmission method of typhoid/paratyphoid?
Faecal-oral from contaminated water (poor sanitation)
Found in Asia, Africa, South America
Salmonella enterica serovar typhi/paratyphi A, B, or C (aerobic Gram-ve rod in the group Enterobacteriaceae)
This microbe can be differentiated from E.coli by plating on lactose (E.coli ferments lactose, S. enterica does not)
Endotoxin called invasin allows intracellular growth
Fimbriae adhere to epithelium over ileal lymphatic tissue (Peyer’s patches)
Also known as enteric fever.
What are the typical history and examination findings in typhoid/paratyphoid infection?
Incubation period = 7-14 days
S&S: (note: paratyphoid generally milder)
- fever
- headache
- abdominal discomfort
- constipation
- dry cough
- heaptosplenomegaly
- sometimes rash
- relative bradycardia
Complications: intestinal haemorrhage & perforation
Why is it significant that typhoid infection presents with fever and bradycardia?
Fever usually causes tachycardia
What are the investigations and treatment options for typhoid/paratyphoid infection?
Investigations:
- moderate anaemia
- relative lymphopenia (low lymphocytes)
- raised LFTs (transaminase & bilirubin)
- blood culture (?systemic infection)
- stool culture
Treatment: ceftriaxone or azithromycin (macrolide) for 7-14 days (as organism is intracellular)
note: bacterium has become resistant to previous antibiotics used for treatment
How can typhoid/paratyphoid infection be prevented?
- food & hygiene precautions
- typhoid vaccination (50%-75% effective, antigen or attenuated bacteria) available for high risk travel & lab personnel
What symptoms do non-typhoidal Salmonella species generally cause?
e.g. Salmonella typhimurium, Salmonella enteritidis
Food poisoning
S&S:
- diarrhoea
- fever
- vomiting
- abdominal pain
Treatment only required if bacteraemia/deep-seated infection occurs (infection is generally self-limiting)
What is the aetiology and transmission method of brucellosis?
Brucellus abortus (cattle) or Brucella melitensis (goats & sheep) (zoonosis)
Gram-ve coccobacillus
Southern Europe, Africa, Asia, Central & South America
Transmitted through skin breaks/GI tract (milk ingestion)
