Week 2: Infectious disease (3)(ID summaries) Flashcards
malaria: demographic affected: Malaria
- Commonest imported infection in the UK
- 75% falciparum (90% of cases from Africa)
- 25% Ovale (90% of cases from India)
- Initially ALWAYS REAT AS FACIPARUM
o Mortality rate 10-20%
o More common in travellers
- Initially ALWAYS REAT AS FACIPARUM
pathogen: malaria
- 5 main species of Plasmodium
Falciparum
Vivax
Ovale
Malaria
Knowlesii - Vector= female anopheles mosquito
course of illness: malaria
o Incubation period
Minimum 7 days
• Falciparum- 4 weeks
• Vivax/ ovale up to a year (lay dormant in the liver)
Signs and symptoms: Malaria
- Fever/ chills and sweats
- Cycle every 3rd or 4th day
- Severe headache, malaise, myalgia, vague abdominal pain, nausea, vomiting
- Examination- few signs except fever +- splenomegaly
Diagnosis/investigations: Malaria
o X3 blood films to diagnose
o Bloods (FBC, U&E, LFTs, glucose, coagulation)
- Anaemia
- Thrombocytopenia
- Leukopenia
- Abnormal Liver test
o Rapid antigen test
o Head CT if CNS symptoms
o CXR
management: Malaria
Non-falciparum
- oral artemisinin combination therapy (ACT)
Falciparum
Admit all patients with falciparum
- uncomplicated
- artemisinin combination therapy (ACT).
- or quinine with doxycyline
- complicated
- IV artesunate
- or intravenous quinine (need to monitor for hypoglycaemia)
Prevention: Malaria
Nets, antimalarials (DEET), repellent
When diagnosing infectious disease via blood screens can use PCR or serology
- IgM= recent infection
- IgG= cant tell how recent
Life cycle of Plasmodium species
- Mosquito feeds on human and malaria sporozoites enter in blood and infect liver cells
- Parasite develops into mature schizonts creating many merozoites which burst out of the cell and enter blood cell and infect blood cells
- Causing RBC to burst and releasing more merozoites
- These go and infect other blood cells and can cause anaemia and microvascular occlusion of organs (very sticky cells)- end organ damage e.g. kidney
- Some merozoites develop into gametocytes which can be ingested by other mosquitos
Complex life-cycle makes malaria hard to create a vaccine
Malaria treatment depends on
species
P. falciparum (‘malignant’) treatment
o Artemisinin ( IV artesunate/PO Riamet) o Quinine plus doxycycline (7 days) o Plus supportive therapy/ ITU
P. vivax, ovale, malaria (‘benign’)
o Chloroquine (3-4 days)
o +primaquine (14 days)
Hypnozoites- liver stage
Can recur months-years later
Severe falciparum malaria
Untreated P.Falciparum infection can cause hypoglycaemia, renal failure, pulmonary oedema and neurologic deterioration leading to death.
- Impaired consciousness or seizures
- Renal impairment (oliguria <0.4ml/kg bodyweight per hour or creatinine >256umol/l)
- Acidosis <7.3)
- Hypoglycaemia <2.2mmol/l)
- Pulmonary oedema or ARDS
- Haemoglobin <80 g/l
- Spontaneous bleeding- IDC
- Shock (algid malaria <90/60 mmHg)
demographic affected: dengue fever
o Found throughout the world: Africa, Asia, India, S and C America
o ‘re-infection’ mainly affects those living in Dengue endemic areas
Children
Rare in travellers
Pathogen: dengue virus
o Arbovirus (arthropod born virus) 4 serotypes o Vector= mosquito
Course of illness: Dengue fever
o First infection ranges from asymptomatic to non-specific febrile illness (classic dengue)
Lasts 1-5 days
Improves 3-4 days after rash
Supportive treatment only
o Re-infection with different serotype is very dangerous
Antibody dependent enhancement (immune system overdrive)
• Dengue haemorrhagic fever (children)
• Dengue shock syndrome
signs and symptoms: dengue fever
- a high temperature, or feeling hot or shivery.
- a severe headache.
- pain behind the eyes.
- muscle and joint pain.
- feeling or being sick.
- a widespread red rash.
- tummy pain and loss of appetite.
diagnosis: dengue
-
PCR
- Serology e.g. IgM and IgG
diagnosis: dengue
- PCR
- Serology e.g. IgM and IgG
management of dengue fever
There is no specific treatment for dengue fever. Fever reducers and pain killers can be taken to control the symptoms of muscle aches and pains, and fever. The best options to treat these symptoms are acetaminophen or paracetamo
prevention : dengue
- Vaccine (only in people over certain age)
demographic affected: typhoid and paratyphoid fever
- Disease of poor sanitation
- Mainly Asia, Africa, S america
- Travel related in UK
pathogen: typhoid and para
- Salmonella typhi/paratyphi A,B, or C- Gram negative bacilli- Enterobacteriaceae
- Virulence= low infectious dose
- Survives gastric acid
- Fimbriae adhere to ileal lymphoid tissue (Peyers patches) RE system/blood
- Reside within macrophages (liver/spleen/ bone marrow)
- Faecal-oral from contaminated food/water
course of illness: typhoid
- Incubation period: 7-14 days
signs and symptoms: typhoid
- Systemic disease
- Fever, headache, abdominal discomfort, dry cough
- Relative bradycardia
- Complications
- Intestinal haemorrhage and perforation; seeding
- Paratyphoid is generally milder