malaria

References:

1. Global Infectious Diseases and Epidemiology Online Network: Infectious Diseases of the Philippines, 2013 eBook Edition, ISBN 978-1-61755-582-4, by Stephen Berger. Accessed here.

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Agent	PARASITE - Protozoa. Sporozoa, Coccidea, Haemosporida: Plasmodium spp.
Reservoir	Human Primate (Plasmodium knowlesi)
Vector	Mosquito (Anopheles)
Vehicle	Blood
Incubation Period	12 to 30 days
Diagnostic Tests	Examination of blood smear Serology, antigen, and microscopic techniques Nucleic acid amplification
Typical Adult Therapy	Resistant falcip: Lumefantrine/Artemether OR Quinine + Doxycycline or Clindamycin OR Atovaquone/proguanil OR Artesunate IV if severe malaria If sens., Chloroquine 1g, then 500 mg at 6, 24 & 48 hrs. If P. ovale or P. vivax - follow with Primaquine
Typical Pediatric Therapy	Resistant falcip: Lumefantrine/Artemether OR Quinine + Clindamycin OR Atovaquone/proguanil OR Artesunate (>age 8) IV (severe malaria) If sens, Chloroquine 10 mg/kg, then 5 mg/kg at 6, 24, & 48 hrs. If P. ovale or P. vivax - follow with Primaquine
Clinical Hints	Fever, headache, rigors (“shaking chills”), vomiting, myalgia, diaphoresis and hemolytic anemia; fever pattern (every other or every third day) and splenomegaly may be present; clinical disease may relapse after 7 (ovale and vivax) to 40 (malariae) years.
Synonyms	Ague, Bilious remittent fever, Chagres fever, Estiautumnal fever, March fever, Marsh fever, Paludism, Paludismo, Plasmodium falciparum, Plasmodium knowlesi, Plasmodium malariae, Plasmodium ovale, Plasmodium vivax.

WHO Case Definition for Surveillance

(For use in endemic areas and people exposed to malaria, e.g., a history of visit to endemic area)

• Malaria must be defined in association with clinical disease symptoms.
• The case definition for malaria cannot be uniform: it will vary according to how malaria is perceived in a given country, local patterns of transmission, and disease consequences.
• The suggested definitions are deliberately broad.
• Each national malaria control program must adapt the definition and introduce additional indicators to make it more applicable to local epidemiology and control targets.

Clinical description

• Signs and symptoms vary; most patients experience fever.
• Splenomegaly and anemia are commonly associated signs.
• Common but non-specific symptoms include otherwise unexplained headache, back pain, chills, sweating, myalgia, nausea, vomiting.
• Untreated Plasmodium falciparum infection can lead to coma, generalized convulsions, hyperparasitemia, normocytic anemia, disturbances of fluid, electrolyte, and acid-base balance, renal failure, hypoglycemia, hyperpyrexia, hemoglobinuria, circulatory collapse / shock, spontaneous bleeding (disseminated intravascular coagulation), pulmonary edema, and death.

Laboratory criteria for diagnosis: Demonstration of malaria parasites in blood films (mainly asexual forms).

Case classification

1. In areas without access to laboratory-based diagnosis.
   • Probable uncomplicated malaria: A person with symptoms and/or signs of malaria who receives anti-malarial treatment.
   • Probable severe malaria: A patient who requires hospitalization for symptoms and signs of severe malaria and receives anti-malarial treatment.
   • Probable malaria death: death of a patient diagnosed with probable severe malaria.
2. In areas with access to laboratory-based diagnosis.
   • Asymptomatic malaria: A person with no recent history of symptoms and/or signs of malaria who shows laboratory confirmation of parasitemia.
   • Confirmed uncomplicated malaria: A patient with symptoms and/or signs of malaria who received anti-malarial treatment, with laboratory confirmation of diagnosis.

Acute Infection

Most cases present with non-specific signs suggestive of ‘sepsis,’ such as fever, rigors, headache and myalgia.

• Clinical findings include cough, fatigue, malaise, arthralgia, myalgia, headache, and diaphoresis.
• In Africa, tickborne relapsing fever and rabies are often mis-diagnosed as malaria.

The typical malarial paroxysm begins with rigors lasting 1 to 2 hours, followed by high fever.

• This is followed by marked diaphoresis and a fall in temperature.
• Tertian (fever every other day) fever may occur in infection by P. falciparum, P. vivax and P. ovale; quartan (every third day) fever with P. malariae infection; and daily fever with P. knowlesi infection.
• P. knowlesi malaria appears to be more severe than P. malariae malaria, with higher rates of parasitemia and fatality.
• ‘Classical’ fever patterns are rarely helpful, and anemia and splenomegaly develop only after several attacks.
• Less common findings include anorexia, vomiting, diarrhea and hypotension.
• In some cases, malaria may present as fever accompanied by an urticarial rash.

Complications

Complications include pulmonary disease (ARDS), encephalopathy (cerebral malaria), nephropathy, retinopathy, cranial nerve palsy, cerebellar ataxia, acute disseminated encephalomyelitis, hypocalcemia with tetany, shock (‘algid malaria’), purpura fulminans, massive diarrhea, pancreatitis, myocarditis and dysfunction of other organs.

• Patients with falciparum malaria are at increased risk for bacteremia.
• Occasionally, patients experience Post-malaria Neurological Syndrome: acute confusion, cerebellar ataxia, diffuse cerebral demyelination, seizures, hearing loss, cognitive dysfunction or other neuropsychiatric findings several days to weeks following successful treatment of falciparum malaria.
• Plasmodium falciparum infection accounts for most complications and deaths from malaria; however, severe disease may occasionally complicate infection by other species.
• The presence of malarial retinopathy is associated with a poor prognosis.
• P. falciparum is also responsible for most malarial drug resistance.
• Maternal infection is associated with vertical transmission to the newborn, fetal loss and low birth weight in infants.
• 5% of African children with severe malaria were found to have concomitant bacteremia
• Severe and fatal disease associated with Plasmodium vivax infection is increasingly reported in recent years. Instances of acute glomerulonephritis, IgA nephropathy, renal cortical necrosis, acalculous cholecystitis, jaundice, pancreatitis, thrombocytopenia, shock, peripheral gangrene, cerebral malaria, hypoglycemia and acute respiratory distress syndrome have been reported with Plasmodium vivax infections.
• Plasmodium malariae infection is rarely associated with severe illness; and may lead to renal glomerular damage and nephrotic syndrome.
• Pericarditis and acute respiratory distress syndrome have been reported in Plasmodium ovale infection.

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Relapse

Relapse may occur months to years following the initial episode.

• Relapses of P. vivax and P. ovale infection result from release of parasites which had remained dormant in the liver.
• As such, treatment of infection by either of these two species should include a drug (e.g., primaquine) active against intrahepatic parasites.
• Although infections caused by P. falciparum and P. knowelsi do not relapse, reinfection may occur.

Plasmodium malariae persists without symptoms in the blood, rather than the liver.

• Relapse has been reported as long as 40 to 50 years following exit from an endemic area.