MICRO: Fever in the returning traveller Flashcards
- PVI - presumed viral infection
- 70% of those returning from Africa had a tropical illness
- Risk of tropical infection higher among VFRs (visiting friends and relatives)
- Non-tropical were common among returnees from SE Asia (45%)
- but enteric fever (34%) and dengue (20%) remain important
Fever and Rash - Dengue, Chikungunya, rickettsial, enteric fever (rose spots), acute HIV, measles
Fever and abdominal pain - Enteric fever, amoebic liver abscess
Undifferentiated fever and normal/ low blood count - Dengue, malaria, rickettsial, enteric, Chikungunya
Fever and haemorrhage - Viral haemorrhagic fevers (dengue and others), meningococcaemia, letposiprosis, rickettsial
Fever and eosinophilia - Acute schistosomiasis, drug hypersensitivity, fascioliasis, other parasitic
Fever and pulmonary infiltrates - Bacterial/ viral pathogens, legionellosis, acute schistosomiasis, Q fever
Fever and altered mental status - Cerebral malaria, viral or bacterial meningoencephalitis, African trypanosomiasis
Mononucleosis syndrome - EBV, CMV, Toxoplasma, acute HIV
Fever persisting >2 weeks - Malaria, enteric fever, EBV, CMV, toxoplasmosis, acute HIV, acute schistosomiasis, brucellosis, TB, Q fever, visceral leishmaniasis (rare)
Fever with onset >6 weeks after travel - vivax malaria, acute hepatitis (B,C,E), TB, amoebic liver abscess
RDT = rapid diagnostic test
Malaria paracites look like “headphones”, there are two of them in the cell so it’s more likely falciparum
Case 1:
High prasitaemia - most helpful for guiding treatment
IV artesunate gives 30% reduction in mortality vs IV quinine in severe malaria
NB: 20% means that 20% of erythrocytes have been infected with malaria parasites
What % of African children deaths are caused by Malaria?
20%
African child may have 5 episodes of malaria per year affecting growth and development
How many cases of Malaria is seen in the UK per year?
~1500
What are the 5 types of Plasmodium species?
P. falciparum - MOST SEVERE - increased drug resistance, infects erythrocytes of all stages
P. vivax and P. ovale
P. malariae
P. knowlesi - behaves like falciparum
What is the life cycle of malaria?
NB: vivax and ovale have a hypnozoites stage in the liver (parasites are asleep in the liver) so targeted malarials need to be given for that
In humans: erythrocytic and exoerythrocytic stages
Describe techniques for prevention of malaria.
Repellants/nets
Prophylaxis - malorone/mefloquine/doxycycline
Take note of region (may recommend different medication by region), individual characteristics (e.g. pregnancy) etc
How does malaria present?
Fevers – cyclical or continuous with spikes
Malaria paroxysm – chills, high fever, sweats
Severe Malaria:
- High parasitaemia* or schizont
- Altered consciousness with/ without seizures
- Respiratory distress or ARDS
- Circulatory collapse
- Metabolic acidosis
- Renal failure, haemoglobinuria (blackwater fever)
- Hepatic failure
- Coagulopathy +/-DIC
- Severe anaemia or massive intravascular haemolysis
- Hypoglycemia
What is a schizont an indication of?
Even one schizont indicates a severe malaria
Schizont is a cell with multiple parasites which could burst and cause a rapid rise in parasitaemia
What is the % parasitaemia used in the UK for treatment cut-off?
2% is usually the cut-off used in guidelines to treat.
What laboratory tests are used for malaria?
Thick and thin blood smears x3
- Field’s or Giemsa* stain
- Thick: screen parasites (sensitive)
- Thin: identify species & quantify parasitaemia
Malaria antigen detection tests
- Paracheck-Pf® (detect plasmodial HRP-II)
- OptiMAL-IT (parasite LDH)
*Giemsa for better detection of species
Summarise the management of malaria.
- Decide whether falciparum or not
- If falciparum check if severe or mild
- If non-falciparum check for G6PD deficiency
Milf falciparum malaria:
Not vomiting, Parasitaemia <2%, Ambulant = Oral Malarone ™ (atovaquone and proguanil), 4 tablets daily with food for three days
ACT – artemisinin combination therapies =
- E.g Riamet/ Co-artem – Artemisinin & Lumefantrine,
- Oral quinine 600mg tds (salt)
- then doxycycline 100mg od for 1 week
Severe falciparum malaria:
- ABC
- Correct Hypoglycamia
- Cautious rehydration (avoid overload)
- Organ support as necessary
IV Artesunate in preference to IV Quinine
Daily parasitaemia then PO follow on eg with ACT
What is a side effect of IV quinine vs artesunate?
Artesunate side effects: delayed haemolysis
Quinine side effects: cinchonism, arrhythmias, hyperinsulinaemia
Case 2: Some conjunctival injection, travelled abroad to SE Asia, arthralgia, thrombocytopenia,, no anti-malarials but told not needed.
Dengue
Dengue
Aedes mosquito
What type of disease is Dengue caused by? How many serotypes?
Flavivirus
4 main serotypes - reinfection can occur and may be worse
Mostly URBAN
How common is Dengue in the UK?
Seen in ~340/year mostly from SE Asia
What is the presentation and onset of Dengue?
- Short incubation
- Fever, retro-orbital headache, myalgia, erythrodermic rash
- Severe - bleeding, hepatitis, encephalitis, myocarditis
- Rash in 50%
What is the spectrum of disease in Dengue?
Usually mild self-limited illness - mild febrile/ dengue haemorrhagic/ dengue shock.
DHF and shock syndromes rare in travellers - Occur in those previously infected with a different Dengue serotype
