Malaria

Vivax, ovale and malariae malarias

• Incubation period for P. vivax is 12-17 days, for P. ovale it is 15-18 days, and for P. malariae it is 18-40 days.

• Prodromal symptoms are more severe with P. malariae infections.

• These "benign" malarias also present with paroxysmal feverish symptoms. In vivax and ovale malaria infections, the characteristic tertian interval (48 hours interval between fever spikes or fever on alternate days) may be seen. In P. malariae infections, the quartan interval (72 hours interval between spikes or fever every 3rd day) may be seen.

• Patients suffering from vivax malaria may become anaemic, thrombocytopenic and mildly jaundiced with tender hepatosplenomegaly. Splenic rupture is more common with vivax malaria.

• The acute symptoms of ovale and malariae malarias may be as severe as those of vivax infection, but anaemia is less severe and the risk of splenic rupture is lower.

• P. malariae infections are associated with gross splenomegaly, but splenic ruprure is less common. P. malariae causes glomerulonephritis and an immune-complex nephropathy resulting in nephrotic syndrome.

• Vivax and ovale malarias have a persistant hepatic cycle that may give rise to relapses. P. malariae does not relapse, but a persisting undetectable parasitaemia may cause repeated exacerbations.

• Occasionally, vivax malaria can produce complications similar to those of falciparum malaria.

Falciparum malaria (malignant tertian or subtertian malaria)

• The incubation period ranges from 7 to 14 days (means 12 days).

• Prodromal symptoms like malaise, headache, myalgia, anorexia and mild fever may last for several days before the onset of the classical "malarial paroxysms".

• In a classical malarial paroxysm suddenly the patient feels inexplicably cold and apprehensive. Mild shivering follows, which quickly turns into violent shaking with teeth rattling. There is intense peripheral vasoconstriction and goose flesh. The rapid increase in temperature may trigger febrile convulsions. The rigor lasts up to 1 hour. This is followed by a hot flush with throbbing headache, palpitations, tachypnoea, prostration, postural syncope and vomiting. The temperature reaches its peak. Finally, a drenching sweat breaks off and the fever defervesces over the next few hours. The exhausted patient sleeps off. The whole paroxysm lasts about 8-12 hours.

• A high irregular spiking unremitting fever or daily (quotidian) paroxysm is more commonly seen in falciparum malaria than the classically described tertian or subtertian periodicity (48 and 36 hours between fever spikes).

• The patient with falciparum malaria usually looks severely ill with "typhoid" facies.

• The patient is often anaemic and jaundiced with moderate tender enlargemetn of the spleen and liver.

• Neurological complications of falciparum malaria can manifest as acute headache, irritability, agitation, seizures, psychosis and impaired consiousness.

Dengue

Presently, WHO classifies dengue viral infections into non-severe dengue (with and without warning signs) and severe dengue.

Non-severe dengue without warning signs:

Probable dengue

• Live in/travel to endemic area

• Fever and two of the following criteria

1. Nausea and vomiting

2. Rash

3. Aches and pains

4. Tourniquet test positive

5. Leucopenia

6. No warning sign

Laboratory-confirmed dengues

Non-severe dengue with warning signs:

Presence of warning signs

• Abdominal pain or tenderness

• Persistent vomiting

• Clinical fluid accumulation

• Mucosal bleed

• Lethargy and restlessness

• Liver enlargement > 2cm

• Laboratory: Increase in haematocrit concurrent with rapid decrease in platelet count

Severe dengue

• Severe plasma leakage leading to

1. Shock (DSS)

2. Fluid accumulation with respiratory distress

• Severe bleeding

1. As evaluated by clinician

• Severe organ involvement

1. Liver: AST or ALT ≥ 1000

2. CNS: Impaired consiousness

3. Heart and other organs

Giardiasis

• Incubation period is 1-3 weeks (median 7-10 days).

• Starts as diarrhoea, nausea, vomiting, anorexia, weakness and abdominal pain. Fever and blood in stool are rare.

• Symptoms may persist from a few days to weeks or months to years.

• Individuals with chronic giardiasis may present with or without having experienced antecedent acute symptoms.

• Diarrhoea may not be a prominent symptom in these patients who often have increased flatus, loose stools, malabsorption, weight loss and growth retardation.