infectious diseases Flashcards
(54 cards)
what is a viral exanthem set the scene girlie
An exanthem is a widespread rash often accompanied by systemic symptoms of infection. While common in childhood, exanthems can also occur in adults.
viral exanthema common causes
chickenpox, measles, rubella, roseola, and parvovirus B19, among others.
important differential diagnosis to rule out in children with exanthema presentation
An important differential diagnosis in children is meningococcal sepsis.
general signs and symptoms of viral exanthema
A prodromal phase of systemic symptoms typically occurs before rash onset.
These include fever, malaise, headache, abdominal pain, irritability, generalised aching and loss of appetite.
The presentation of exanthematous rashes are variable.
The rash is widespread but may be more noticeable on the trunk, and may present as spots or blotches, with or without pruritis.
pruritic papules, vesicles and pustules which later crust over virus
chickenpox
5-10mm macules beginning on the face/neck and spreading to the trunk and limbs within days. Classically associated with Koplick spots and conjunctivitis.
measles
pale pink rash beginning on the face and spreading within hours to the trunk and limbs
rubella
typically associated with a prodromal high fever which may cause feibrile convulsions. As this subsides a mild erythematous rash appears on the face and trunk for 1-3 days.
roseola infantum
‘slapped cheek syndrome’ causes a red rash on the cheeks, followed by a lace-like pattern of erythema on the rest of the body. It is associated with arthralgia and aplastic crises in those at higher risk, and can cause foetal hydrops in pregnancy.
parvovirus B19
usually affects young adults. Begins with an oval-shaped ‘herald patch’ before developing into a ‘Christmas tree’ pattern of plaques on the trunk. It is typically self-limiting and lasts 6-12 weeks.
PYTERIASIS ROSEA
investigations done for viral exanthema
Common childhood exanthema can usually be diagnosed clinically, unless there are signs of complications or confirmatory tests are needed.
Some tests for an undifferentiated exanethem may include:
Viral swab: culture, immunofluorescence & PCR
Blood tests: serology, PCR, ANA, specific antibodies
HIV testing
management of exanthema oresentation
If a patient is very systemically unwell, they may need admission to hospital. Adopt an A-E approach, seek senior help early and initiate the sepsis six if sepsis is suspected.
Otherwise, management of exanthems have two aims:
Treatment specific to the underlying cause, or giving patient information about the likely course of self-limiting illnesses. Please see the relevant pages for management of specific conditions.
Supportive management and self-care, involving antipyretics for fever, emollients to reduce itch, ensuring patients stay hydrated and are safety netted to return for new, worsening or unresolved symptoms.
coplications of viral exanthemas
Febrile convulsion
Recurrence
Complications during pregnancy
Specific complications to illness
Measles: otitis media, pneumonia
Chickenpox: secondary infection, pneumonia
Rubella: complications during pregnancy
Parvovirus: aplastic crisis, hydrops fetalis
what is Primary HIV infection
HIV seroconversion illness, is the phase that commences immediately after the initial exposure to the Human Immunodeficiency Virus (HIV).
This phase is characterised by a surge in viral replication and often coincides with the onset of clinical symptoms.
what characteristics is AIDS defined by
defined as very low CD4 cell levels and the development of opportunistic infections or malignancies also known as AIDS-defining illnesses.
can HIV be transmitted from mother to child?
yes during CHILDBIRTH or BREASTFEEDING
stages of HIV INFECTION
Primary HIV infection, which is associated with symptoms and high infectivity along with immune activation.
Latent phase: usually asymptomatic phase, associated with a low transmission risk. As viral diversity increases, the virus befins to evade the immune response.
Advanced HIV disease (AIDS) whereby the immune system is compromised giving rise to opportunistic infections and malignancies
The most important prognostic factor in HIV
early diagnosis and management, which can prevent progression to advanced disease.
signs and symptoms of primary HIV infection
a mild flu-like illness 2-6 weeks post-exposure. The range of clinical manifestations can span from a mild glandular fever-like syndrome to an evolving encephalopathy. Classic presentations include:
Fever
Lymphadenopathy
Maculopapular rash (commonly found on the upper chest)
Mucosal ulcers
Myalgia
Arthralgia
Fatigue
some may also be asymptomatic
what does the test window period mean in HIV testing
During this period, someone may test negative even though they are infected and can still transmit the virus.
diagnostic investigations of HIV
Laboratory tests:
BLOOD TEST
Third-generation tests detect IgM and IgG antibodies, with highest sensitivity during the initial seroconversion period.
The window period for third-generation tests is 60 days.
Fourth-generation tests also detect serology as well as the p24 antigen, with a window period of 45 days.
Point of care tests: these are similar to third-generation laboratory tests but can be performed in the community with a fingerprick testing kit.
The window period for these is 90 days.
A confirmatory laboratory test is required for diagnosis.
tests performed to facilitate treatment decisions for HIV These may include:
FBC, U&E, LFT’s, liver, bone profile, lipids, HbA1c, TB testing, CXR, ECG, toxoplasma serology
Sexual health screen
Viral load, genotype testing, tropism tests, HLA testing, CD4 count and CD4:8 ratio
MANAGEMENT PRINCIPLES OF HIV
If patients are systemically unwell, they should be admitted to hospital as a matter of urgency.
All patients diagnosed with primary HIV infection should be offered combination antiretroviral therapy (cART), regardless of their CD4 count.
Contact tracing is necessary to identify and notify individuals who may have been exposed to the virus.
Pre- or post- exposure prophylaxis can be offered to those who may be/have been exposed to reduce transmission risk.
It is important to manage any complications in conjunction with specialist teams,
When prescribing any medication for a patient with HIV, seek specialist pharmacy advice as the number of drug interactions is extensive.
A typical HIV cART regime
two nucleoside reverse transcriptase inhibitors and one additional drug.
Nucleoside (NRTIs) e.g. Tenofovir, Abacavir, Emtricitabine, Lamivudine, Zidovudine
(other drugs for reference:
Reverse transcriptase inhibitors
Non-nucleoside (NNRTIs) e.g. Efavirenz, Nevirapine, Rilpivirine
Protease inhibitors e.g. Darunavir, Lopinavir/ritonavir, Saquinavir
Integrase inhibitors e.g. Dolutegravir, Raltegravir
CCR5 antagonist e.g. Maraviroc
Fusion inhibitors e.g. Enfuvirtide)
