Malaria Dengue Fever Typhoid Fever Hepatitis A

Definition Protozoa parasite injected by Anopheles mosquitoes multiply in RBCs causing haemolysis, sequestration and cytokine release.

RNA flavivirus (4 types) causing sudden fever, extreme myalgias and arthralgias.

Bacterial infection with salmonella typhi (G- bacillus), causnig severe diarrhoea

Hepatits A virus (HAV), that is not chronic or pregressive and has no permament effect on liver, acutely causes liver damage using body’s own immune response rather than viral cytotoxicity.

Mode of Transmission Mosquito vector, transfusion, vertical, needlestick

‘Aedes’ mosquitoes Faecal-oral route, complicated by asymptomatic typhoid (unknowing carriers)

Faecal-oral route,

Incubation period (link to case) Millsy

Signs and symptoms Millsy

Ix and Common Findings

Basic principles:Parasite = microscopyBacteria = cultureVirus = serology

Diagnosis confirmed by: Thick and Thin Blood filmsOther Common Findings: FBE (anaemia, thrombocytopenia, rarely leukocytosis), LFT derangement, parameters suggestive of haemolysis (haptoglobin, LDH, reticulocyte count), hypoglycemia, ABG (lactic acidosis), UEC (renal failure), Urinalysis (hemoglobinuria, proteinuria, casts).Note: Rapid ward serology tests e.g. ParaSight F, can be performed to identify P. Falciparum, however they are not as sensitive as microscopy, nor do they provide a parasite count (required for management).

Diagnosis confirmed by: Serology (e.g. arbovirus serology) and PCR studiesOther Common Findings: FBE (thrombocytopenia, leukopenia, hematocrit increased due to plasma leakage), LFT (AST elevated, decreased albumin), deranged coag profile (prolonged PT, APTT and decreased fibrinogen), UEC (electrolyte imbalances-hyponatremia, elevated BUN), ABG (acidosis if dengue shock syndrome), positive tourniquet test (determines capillary fragility/hemorrhagic tendency, by applying blood pressure cuff and inflating it to a point between systolic and diastolic BPs for 5 mins. The test is positive if there are 10 or more petechiae per square inch). CXR may reveal pleural effusions.

Diagnosis confirmed by: Cultures - blood, stool, urine - bone marrow culture has highest yield Other Common Findings: FBE (anaemia, thrombocytopenia, relative lymphopenia), elevated ESR, coag profile deranged (elevated PT and APTT, decreased fibrinogen), LFT (raised ALT and serum bilirubin), UEC (hyponatremia, hypokalemia), serum ALT:LDH ratio of less than 9:1 helps to distinguish typhoid from viral hepatitis (viral hep has >9:1). PCR studies, and other serologic tests (e.g. Widal test) can also be performed to diagnose typhoid, but they are not widely available.

Diagnosis confirmed by: Serology for anti HepA IgMOther Common Findings: serum transaminases/ALT rise 22-40d after exposure, IgM rises from approx. day 25 and signifies recent infection. IgG remains detectable for life and appears soon after IgM - IgG means immunity has been acquired and appears normally in immunized patients. LFT (raised ALT, AST and raised ALP in the acute stages of infection, raised bilirubin, decreased serum albumin), Coag derangement (raised PT = very bad - may indicate hepatic failure, particularly in the setting of encephalopathy), FBE (lymphocytosis, rarely pancytopenia)

Treatment Dobbo

Jenny’s Ix Findings• FBE

• HB 11, WCC 7.0, Plt 110

• HB 10, WCC 7.3, Plt 90

• HB 9, WCC 7.2, Plt 96

• HB 9.5, WCC 7.2, Plt 115

• UECs

• Na 140, K 4.0, Ur 7.0, Cr 110

• LFTs

• Mildly elevated ALT and bilirubin, otherwise normal

• Atypical pneumonia - Legionella, Chlamydia species, Mycoplasma pneumoniae, Pneumocystis jiroveci serology - pending

• CXR - clear

• Malarial Thick and Thin Film

• Negative

• Positive for plasmodium falciparum, parasite count 0.2%

• parasite count 0.1%

• parasite count 0%

• Hep A serology - Total Ab positive, IgM pending

• Hep B serology - Surface Antibody positive, surface pending

• Arbovirus (dengue) serology - pending

• HIV serology - negative

• Pregnancy Test - pending

Malarial Thick and Thin Blood Films

• 3 thick and thin smears 12-24hrs apart should be obtained

• Highest yield of peripheral parasites occurs during or soon after a fever spike; however smears should not be delayed to await a fever spike.

• Thin Films - qualitative (speciation)

• Drop of blood on specimen slide

• Clean spreader slide held at an angle of 45 degrees over droplet of blood

• Spread the blood along the specimen slide evenly and thinly

• Wait until blood sample is dry before you fix the sample using methanol, then stain.

• Thick Films - quantitative (parasite count)

• Drop of blood on specimen slide

• Use another clean slide to spread the droplet of blood in a circle approx. 1-2cm in diameter

• Wait until blood sample is dry before staining (should not be fixed)

Findings P falciparum P vivax P ovale P malariae

Only early forms present in peripheral blood

Yes No No No

Multiply-infected RBCs

Often Occasionally Rare Rare

Age of infected RBCs

RBCs of all ages Young RBCs Young RBCs Old RBCs

Schüffner dots No Yes Yes No

Other features Cells have thin cytoplasm, 1 or 2 chromatin dots, and applique forms.

Late trophozoites develop pleomorphic cytoplasm.

Infected RBCs become oval with tufted edges.

Bandlike trophozoites are distinctive.

Slides

• Plasmodium falciparum

• P vivax

• P ovale

• P malariae

• Normal

Malaria Dengue Fever Typhoid Fever Hepatitis A

Definition Protozoa parasite injected by Anopheles mosquitoes multiply in RBCs causing haemolysis, sequestration and cytokine release.

RNA flavivirus (4 types) causing sudden fever, extreme myalgias and arthralgias.

Bacterial infection with salmonella typhi (G- bacillus), causnig severe diarrhoea

Hepatits A virus (HAV), that is not chronic or pregressive and has no permament effect on liver, acutely causes liver damage using body’s own immune response rather than viral cytotoxicity.

Mode of Transmission Mosquito vector, transfusion, vertical, needlestick

‘Aedes’ mosquitoes Faecal-oral route, complicated by asymptomatic typhoid (unknowing carriers)

Faecal-oral route,

Incubation period (link to case) Millsy

Signs and symptoms Millsy

Ix and Common Findings

Basic principles:Parasite = microscopyBacteria = cultureVirus = serology

Diagnosis confirmed by: Thick and Thin Blood filmsOther Common Findings: FBE (anaemia, thrombocytopenia, rarely leukocytosis), LFT derangement, parameters suggestive of haemolysis (haptoglobin, LDH, reticulocyte count), hypoglycemia, ABG (lactic acidosis), UEC (renal failure), Urinalysis (hemoglobinuria, proteinuria, casts).Note: Rapid ward serology tests e.g. ParaSight F, can be performed to identify P. Falciparum, however they are not as sensitive as microscopy, nor do they provide a parasite count (required for management).

Diagnosis confirmed by: Serology (e.g. arbovirus serology) and PCR studiesOther Common Findings: FBE (thrombocytopenia, leukopenia, hematocrit increased due to plasma leakage), LFT (AST elevated, decreased albumin), deranged coag profile (prolonged PT, APTT and decreased fibrinogen), UEC (electrolyte imbalances-hyponatremia, elevated BUN), ABG (acidosis if dengue shock syndrome), positive tourniquet test (determines capillary fragility/hemorrhagic tendency, by applying blood pressure cuff and inflating it to a point between systolic and diastolic BPs for 5 mins. The test is positive if there are 10 or more petechiae per square inch). CXR may reveal pleural effusions.

Diagnosis confirmed by: Cultures - bone marrow, blood, stool, urine - bone marrow culture has highest yield Other Common Findings: FBE (anaemia, thrombocytopenia, relative lymphopenia), elevated ESR, coag profile deranged (elevated PT and APTT, decreased fibrinogen), LFT (raised ALT and serum bilirubin), UEC (hyponatremia, hypokalemia), serum ALT:LDH ratio of less than 9:1 helps to distinguish typhoid from viral hepatitis (viral hep has >9:1). PCR studies, and other serologic tests (e.g. Widal test) can also be performed to diagnose typhoid, but they are not widely available.

Diagnosis confirmed by: Serology for anti HepA IgMOther Common Findings: serum transaminases/ALT rise 22-40d after exposure, IgM rises from approx. day 25 and signifies recent infection. IgG remains detectable for life and appears soon after IgM - IgG means immunity has been acquired and appears normally in immunized patients. LFT (raised ALT, AST and raised ALP in the acute stages of infection, raised bilirubin, decreased serum albumin), Coag derangement (raised PT = very bad - may indicate hepatic failure, particularly in the setting of encephalopathy), FBE (lymphocytosis, rarely pancytopenia)

Dx supported by findings in thick and thin film, anemia + thrombocytopenia, raised urea & clinical findings (cyclical fever, myalgia, rigors)

clinical findings un-suggestive (no rash, haemorrhagic signs or arthralgia) and AST is normal.

clinical findings un-suggestive (no rash, diarrhea, constant rising fever, or organomegally)

unlikely due to immunization (hence the positive Ab’s), also clinical findings don’t coincide (no clinical signs of hepatic damage or generalized GI upset)

Treatment Dobbo

References

• http://emedicine.medscape.com/article/221134-diagnosis - malaria

• http://emedicine.medscape.com/article/177484-diagnosis - hep a

• http://emedicine.medscape.com/article/215840-diagnosis - dengue

• http://emedicine.medscape.com/article/231135-diagnosis - typhoid

• Oxford Clinical Handbook 7th edn, pp. 382-385, 394, 414, 421

• PBL book case 14 p 41-43

• http://www.rph.wa.gov.au/malaria/diagnosis.html - pics