Travel Related Infections & COVID19 *on IMs

Question 1

• why is travel history important in infection?
• give rough incubation times & modes of transmission in different areas of the world.
• give 4 risk factors and infections gained from them eg animal bite=rabies

Answer 1

-different strains of pathogen that are antigenically different, impacts on protection and antibiotic resistance, infection prevention.
-sub Saharan Africa=less than 10 days, via food/water, usually respiratory, SE Asia=10-20 days, insect/tick bite, GI, S/C America = 10-21 days, sexual contact, jaundice
-mosquito/insect=malaria, dengue
Freshwater=schistosomiasis
Undercooked meat=Salmonella

Question 2

• give some investigations you may order for an unwell patient with malaria
• name 3 species of malaria, which is most common, what is the vector, incubation period and give signs and symptoms
• what treatment would you give for a P. Falciparum infection vs p. Vivax/ovale/malariae?

Answer 2

• FBC, U&Es, glucose, LFTs-ALT,ALP, CRP, coagulation, Blood film on which you can see malaria parasites, head CT if any neurological symptoms.
• falciparum (most common), vivax, ovale, vector is female mosquitos, incubates for min 6 days, (falciparum is malignant ie more deadly, by 4 weeks, vivax/ovale are benign so less severe, up to 1yr in body). Signs=fever, sometimes splenomegaly, symptoms=fever, chills, sweats, headache, dry cough.
• falciparum=artesunate, quinine & doxycycline
• vivax, ovale=chloroquine

Question 3

• give ABC steps for preventing malaria.
• what is enteric fever? Where does it mainly come from?what’s the mechanism of infection?
• what organism does it come from, describe its virulence.
• what is its incubation period? Give symptoms, investigations you’d find and treatment.
• how can you prevent this disease?

Answer 3

• Assess risk= for returning travellers, Bite prevention=repellent adequate clothing, nets, Chemoprophylaxis=use of drugs to prevent disease.
• also known as typhoid and paratyphoid fever, from Asia mainly, faeco oral from contaminated food or water, a systemic disease
• salmonella typhi (bacteria, gram neg bacillus), low infectious dose ie very virulent, survives gastric acid, enters blood, resides in macrophages.
• incubates for 7-14 days, fever headache abdo pain, dry cough and relative bradycardia, investigations=moderate anaemia, raised LFTs,lymphopaenia, blood culture. Treat=multi drug resistant so treated w IV ceftriaxone (cephalosporin) for 7 to 14 days.
• food and water hygiene precaution, typhoid vaccine.

Question 4

• how would you investigate a fever and rash? What could it be?
• what is dengue fever, where is it found in the world, how does a first infection differ from re infection?
• what is another name for viral haemorrhagic fever? Describe its symptoms and mode of spread
• what type of virus is the zika virus?what can it cause, how’s it spread, and treatment.

Answer 4

• could be measles, mumps, rubella, infectious mononucleosis (EBV), acute HIV, dengue fever. Do malaria screening, stool and urine cultures, FBCs, CXR, serology tests.
• most common arbovirus, found mainly in sub and tropical regions, Africa Asia, India etc. First infection can be asymptomatic or classic dengue fever(lasts a few days, supportive treatments), second w a diff subtype can cause dengue shock or dengue haemorrhagic fever in kids
• Ebola, a filovirus, flu w vomiting diarrhoea rashes internal/external bleeding after 5-7 days, treatment is antivirals
• an arbovirus, from mosquitos, spread via sex, causes congenital microcephaly and foetal loss, no treatment or vaccine.

Question 5

• outline COVID 19. What is the structure of coronavirus?
• name some of the family member of coronavirus.
• how is it transmitted? What are some barriers to this?
• so how does it manage to enter cells?

Answer 5

• an acute viral infection of resp tract, highly infectious. Large enveloped pleomorphic particles w distinctive spikes on their surface, have ssRNA , spike S glycoprotein as its antigen, 0.1 micrometers diameter
• SARS COV-2 ie COVID 19, MERS from Middle East, sars cov 1= from Asia, all from bats.
• small droplets, large droplets inhaled via resp route, reps epithelial cells covered in mucus to trap, cilia sweep it up to be swallowed
• virus binds to host receptor(normally ACE2 found in gut kidney lung etc), it invaginate it via receptor mediated endocytosis, then releases spike protein into cytoplasm.

Question 6

• what is thought to be the jncubation period of covid19?
• why are there new variants of this virus appearing?
• what treatments are there for this?

Answer 6

• approx 7 days
• because it’s constantly replicating, life cycle is only around 10 hrs, genetic variation and resistance.
• vaccines eg AstraZeneca, Pfizer.