Infection Flashcards
What microorganisms cause malaria and what is the vector?
- Plasmodium species:
- Plasmodium falciparum, vivax, ovale, malariae
- Female Anopheles mosquito
Describe the infectious cycle of malaria and how it develops in the body
- Female anopheles sucks up infected blood. The malaria in the blood of the gut of the mosquito reproduces to created thousands of sporozoites
- Human gets bitten and the sporozoites enter the bloodstream.
- Sporozoites go to the liver. They can lie dormant for several years as hypnozoites if they’re vivax or ovale.
- Mature in the liver into merozoites. They enter the blood and infect RBCs. In the RBCs they reproduce over 48 hours after which the RBCs rupture releasing loads more merozoites into the blood and causing a haemolytic anaemia.
How does malaria present and what are the signs on examination.
- fever, sweats and rigors
- malaise
- myalgia
- headache
- vomiting
- pallor
- hepatosplenomegaly
- jaundice
How is malaria diagnosed?
- malaria blood film sent using an EDTA bottle
- blood film shows parasites,
- 3 samples sent over 3 consecutive days due to 48 hour cycle of malaria
Management of malaria
Falciparum malaria patient should be admitted as it can be quite severe
- Complicated malaria = artesunate and quinine dihydrochloride
- Uncomplicated = artemether with lumefantrine, proguanil and atovaquone, quinine sulphate, doxycycline
What are the possible complications of falciparum infection
- cerebral malaria
- seizures
- reduced consciousness
- AKI
- pulmonary oedema
- DIC
- severe haemolytic anaemia
- multi-organ failure and death
How can we prevent malaria?
- aware of high risk locations
- mosquito spray
- mosquito nets
- antimalarials
- Proguanil and atavaquone (malarone) = best antimalarial
- Mefloquine
- Doxycycline
Which populations have innate immunity against malaria?
- sickle cell
- G6PD deficiency
- pyruvate kinase deficiency
- thalassaemia
What is the most common cause of meningitis? What type of bacteria is it?
- Neisseria meningitidis
- gram negative diplococcus
What is meningococcal septicaemia?
- meningococcal bacterial infection in bloodstream
- causes the classic ‘non-blanching rash’
Most common cause of meningitis in neonates
- group B streptococcus
How does meningitis present?
- neck stiffness
- fever
- vomiting
- headache
- photophobia
- altered consciousness
- seizures
- non-blanching rash (if meningococcal septicaemia)
- neonates = hypotonia, poor feeding, lethargy, hypothermia, bulging fontanelle
Indication for LP in babies
- under 1 month old + fever
- 1-3 months olds + fever + unwell
- Under 1 year with unexplained fever and other features of serious illness
What are the 2 special tests to look for meningeal irritation?
- Kernig’s = lie on back, flex one hip and knee and slowly straighten the knee, causes spinal pain
- Brudzinski’s = lie on back, use hands to lift their head and neck and flex their chin, flexion of hip and knees is positive
How should bacterial meningitis be managed?
- Urgent stat injection of benzylpenicillin prior to transfer to hospital
- LP for CSF should be performed
- Blood tests for meningococcal PCR
- Less than 3 months = cefotaxime + amoxicillin, over 3 months = ceftriaxone
- Vancomycin if penicillin resistant pneumococcal infection
- Dexamethasone
