Malaria Flashcards by Derrick Obeng

What is the most common tropical parasitical infection

Malaria

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What are the four species of the genus plasmodium

Ovale
Falciparum
Knowlesi
Vivax

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Plasmodium parasite originated from which kind of monkeys

Macaque monkeys

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What are the two distinct patterns of malarial transmission

Stable malaria transmission
Unstable malaria transmission

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What is the incubation period of malaria

7 days or longer

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Incubation period for P. falciparum

7-14 days

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Incubation period for P. vivax

12-17 days

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Incubation period for P. ovale

15-18 days

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Incubation period for P. malariae

18-40 days

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Incubation period for P. knowlesi

9-12 days

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Which two species of plasmodium can remain dormant in the liver (hypnozoites) and relapse (caused by these persistent liver forms may appear months and rarely several years after exposure)

Vivax and ovale

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……… is unable to infect red cells lacking the Duffy blood-group antigen as the antigen is the receptor for its merozoites.

P. vivax

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What are some innate immunity mechanisms against malaria

Lack of Duffy antigen
G6PD deficiency
Alpha and beta thalassemia
Genotype AS

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In malaria, if reinfection of the disease does not occur, the immunity wanes after …….. years

Five

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Neonates are usually protected by maternal antibodies for how many months

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What are some features of severe malaria

Severe anaemia (Hb<5g/dL)
Hypotension and shock (algid malaria) BP < 90/60 mmHg
Noncardiogenic pulmonary edema and acute respiratory distress syndrome
Hyperpyrexia (temperature 38.5°C)
Inability to take oral fluids/feeds, Repeated profuse vomiting
Prostration, i.e. generalized weakness so that the patient cannot walk or sit
Acute kidney injury due to acute tubular necrosis
Severe hemolysis with jaundice
Blackwater fever (Intravascular haemolysis and haemoglobinuria (without G6PD deficiency), increased bilirubin, acute tubular necrosis, haemoglobin casts)

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What are some syndromes resulting from disorders from immunological responses to repeated

Nephrotic syndrome
Hyper-reactive malarial splenomegaly syndrome (HMS)

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What is the pathophysiology of nephrotic syndrome, a complication of malaria normally in children

Antigen-antibody complex binds to the glomerular basement membrane immune complex glomerulopathy causing an intractable nephrotic syndrome which is not responsive to corticosteroids nor eradication of the malaria

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It is a massive enlargement of the spleen due to an abnormal exaggerated immune response to repeated exposure to malaria parasites
It is characterized by massive splenomegaly (at least 10cm), hepatomegaly, polyclonal hypergammaglobulinemia, raised serum immunoglobulin M (IgM) levels and positive malaria antibody test
Hepatic sinusoidal lymphocytosis is also seen
Patient may have features of secondary hypersplenism
It responds clinically and immunologically to malaria prophylaxis with regression of splenomegaly by 40% by 6 months after start of therapy
Is a massive enlargement of the spleen due to an abnormal exaggerated immune response to repeated exposure to malaria parasites
•Is characterized by massive splenomegaly (at least 10cm), hepatomegaly, polyclonal hypergammaglobulinemia, raised serum immunoglobulin M (IgM) levels and positive malaria antibody test
Hepatic sinusoidal lymphocytosis is also seen
Patient may have features of secondary hypersplenism
It responds clinically and immunologically to malaria prophylaxis with regression of splenomegaly by 40% by 6 months after start of therapy
What syndrome is this

HMS

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What is the major criteria for case definition in the Bates and Bedu-Addo diagnostic criteria for HMS

Gross splenomegaly 10 cm or more below the costal margin in adults for which no other cause can be found
Elevated serum IgM level 2 SDs or more above the local mean
Clinical and immunologic responses to antimalarial therapy
Regression of splenomegaly by 40% by 6 months after start of therapy
High IgG antibody levels to plasmodium species (≥1:800)

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What is the minor criteria for case definition in the Bates and Bedu-Addo diagnostic criteria for HMS

Hepatic sinusoidal lymphocytosis
Normal cellular and humoral responses to antigenic challenge, including a normal phytohemagglutination response
Hypersplenism
Lymphocytic proliferation
Familial occurrence

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The differential diagnosis of malaria include every condition that causes ……………………

Acute febrile illness

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What are some differential diagnosis of malaria

Enteric fever, UTI, Pyelonephritis
COVID-19, Viral hemorrhagic fevers, HIV infection, Acute viral hepatitis and other viral illness
Pharyngitis, Sinusitis, Otitis media, Pneumonia, Tuberculosis
Gastroenteritis, Giardiasis, Amebiasis and amebic liver abscess
Pelvic inflammatory disease
Lymphoma
Meningitis, Encephalitis

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What blood smear remains the mainstay of malaria

Giemsa stain

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Which smear is useful for quantification discrimination of parasite species

Thin smear

Which smear is most sensitive for determining if malaria infection is present

Thick smears

A single negative blood film does not rule out falciparum malaria True or false

True

The choice of RDT will depend on ……….

The species prevalent in that area. In most circumstances, the detection of P. falciparum is most important

Tests using ……….. are more sensitive for detecting P. falciparum than RDTs using pan-malarial antigens

HRP2

RDTs using pLDH are more suitable determining response to treatment and not HRP-2 tests. Why

RDTs may remain positive several days or weeks following effective treatment. HRP-2 antigen persists in the blood circulation 2–3 weeks after treatment and so is not useful for determining response to treatment; RDTs using pLDH are more suitable for this purpo

In immune populations, highly sensitive molecular tests, such as ………, have limited value because subclinical infections, which are not routinely treated, are common

PCR

What condition is the most common cause of fever in the tropics

Malaria

Symptomatic malaria is caused only by the ………… stage of infection

Erythrocytic

Available antimalarial drugs act against the erythrocytic stage, except for ……….., which acts principally against hepatic parasites

Primaquine

What is amodiaquine used to treat

Treatment of P. falciparum, optimally in fixed dose combination with artesunate

What is sulfadoxine-pyrimethamine used to treat

Treatment of P. falciparum, optimally in combination with artesunate, intermittent preventive therapy

What are the artemisinins (artesunate, artemether, dihydroartemisinin) used to treat

Treatment of P. falciparum, in oral combination regimens for uncomplicated disease and parenterally for severe malaria

WHO recommends 6 artemisinin-based combination therapies (ACTs) as first-line therapies for falciparum malaria in nearly all endemic countries. What are these ACTs

Artemether + Lumefantrine Artesunate + Amodiaquine Artesunate + Mefloquine Artesunate + Pyronaridine Artesunate + Sulfadoxine –pyrimethamine

Severe malaria is a medical emergency True or false

True

………….. treatment is indicated for all patients with severe malaria

Parenteral

The standard of care for severe malaria is ……………….

Intravenous artesunate

Intravenous artesunate has been shown to be superior to ………. for the treatment of severe malaria in adults and WHO recommends that IV artesunate be used in preference to quinine for severe falciparum malaria

Quinine

What is the dose of administration for IV artesunate

Intravenous artesunate is administered in four doses of 2.4 mg/kg over 3 days, every 12 hours on day 1, and then daily

Parenteral therapy should be given for at least …… hours with step down to a full course of an oral ……. or oral………. plus ……… once the patient improves

24, ACT, quinine, doxycycline

What is the first line drug for non-falciparum malaria from most areas

Chloroquine

For P vivax or P ovale, eradication of erythrocytic parasites with chloroquine should be accompanied by treatment with ………….. or ………….. (R/O G6PD deficiency) to eradicate hypnozoites, which may lead to relapses with recurrent erythrocytic infection and malaria symptoms after weeks to months if left untreated

Primaquine, Tafenoquine

What are P. malariae infections treated with

Chloroquine

What are some supportive treatments for malaria

Oral or rectal paracetamol and tepid sponging Rehydration with IV fluids for hypovolaemia, electrolyte disorders and acidosis Monitoring renal function and initiating dialysis if indicated Blood transfusion when there are strong clinical indications; e.g., when the haemoglobin concentration is < 5 g/dL or at higher levels if accompanied by hyperparasitaemia Anticonvulsants if indicated Monitoring of blood glucose and correction of hypoglycaemia where necessary Treating DIC if severe enough to cause bleeding; fresh whole blood and fresh frozen plasma may be given

What are some prognosis for malaria

When treated appropriately, uncomplicated malaria generally responds well, with resolution of fevers within 1–2 days Prompt effective treatment reduces the risk of progression to severe disease Severe malaria can progress to death, but many children respond well to therapy With effective treatment most children with cerebral malaria will recover with a minority (5–10%) left with a neurological deficit, such as hemiparesis, cerebellar ataxia or epilepsy Pregnant women are at particular risk during their first pregnancy Malaria in pregnancy also increases the likelihood of poor pregnancy outcomes, with increased prematurity, low birth weight, and mortality

Which part of Asia is considered as the birthplace of antimalarial resistance

South-East Asia and in particular, the Thai-Cambodian border area *This refers to the observation that parasite drug resistance to CQ, SP and mefloquine was first observed in this area, before spreading to other parts of Asia and onto Africa*

Which four countries has been documented to show decreased sensitivity of P. falciparum to artemisinins

Cambodia Myanmar Thailand Vietnam

There is also evidence of a decline in the efficacy of Quinine in parts of …………

South-East Asia

What is recrudescence in malaria

Recrudescence means that the infection has recurred from persistent blood stages of the malaria parasite. Symptoms return after a symptom-free period, and it is caused by parasites surviving in the blood as a result of inadequate or ineffective treatment

What is relapse in malaria

Relapse is when symptoms reappear after the parasites have been eliminated from blood but persist as dormant hypnozoites in liver cells

Episodes of illness may recur after the primary infection due to recrudescence of small numbers of blood stage parasites. Which species of plasmodium are responsible for this

P. falciparum P. malariae

Recurrent fever may occur due to relapse from liver hypnozoites. What plasmodium species are responsible for these

P. vivax and P. ovale

Relapses occur despite drug treatment to eliminate the red cell parasite stages in primary infection and can only be prevented by specific therapy to achieve a ‘radical’ cure with the eradication of the hypnozoites True or false

True

Chemoprophylactic regimen are fully protective True or false

False. No chemoprophylactic regimen is fully protective

List some vulnerable groups chemoprophylactic measures are recommended for

Pregnant women Non-immune travelers

Mention some chemoprophylaxis for malaria

Atovaquone-proguanil (Malarone) Doxycycline Mefloquine Chloroquine-sensitive parasites, Primaquine Tafenoquine Sulfadoxine-pyrimethamine (SP)

What is the dose range for artemether and lumefantrine

Artemether - 1.4-4 mg/kg Lumefantrine - 10-16mg/kg

There is a fixed-dose formulation with dispersible or standard tablets of artemether and lumefantrine. What is the mass (in mg) of artemether and lumefantrine in the drug

20g of artemether and 120g of lumefantrine and 80mg of artemether and 480mg of lumefantrine

What is the dosing regimen time for artemether-lumefantrine

0, 8hours, then 12hourly for a total of 3 days

What is the dose of artesunate-amodiaquine

A dose of 4 mg/kg/day artesunate and 10 mg/kg/day amodiaquine is given once or twice a day for 3 days

What is the dosing for dihydroartemisinin-piperaquine

A dose of 4 mg/kg/day dihydroartemisinin and 18 mg/kg/day piperaquine once a day for 3 days

In order of preference, what are the available options for anti-malarial medication for severe malaria

IV/IM Artesunate IM Artemether IV/IM Quinine

In what form should quinine be given

Quinine should be given either by IV in dextrose infusion or IM until patient can swallow, then treatment shall be continued with oral quinine *Blood glucose should be monitored every 4–6 hours, and 5–10% dextrose may be co-administered to decrease the likelihood of hypoglycemia*

Quinine should always be given by slow rate-controlled infusion, never by bolus intravenous injection True or false

True

Quinine causes QTc prolongation and ideally patients receiving intravenous quinine should receive continuous cardiac monitoring; if QTc prolongation exceeds 25% of baseline, the infusion rate should be reduced True or false

True

What is the dosing of IM quinine

IM Quinine: 10 mg/Kg body weight given 8 hourly by deep IM injection, to a maximum dose of 600 mg

What is the dosing for IV Quinine

IV Quinine: 10mg per kg body weight of Quinine Hydrochloride salt

What is the dosing of IV/IM artesunate

IV / IM Artesunate: 2.4 mg/kg body weight given IV/IM on admission (time =0 hour), then at 12 hours and 24 hours then every 24 hours daily till the patient can tolerate oral therapy or up a maximum of seven days

What is the dosing of IM artemether

IM Artemether: 3.2mg per kg body weight as a loading dose, then 1.6mg/kg body weight daily till the patient can tolerate oral therapy or up to a maximum

Give an example of a molecular diagnostic test that is highly sensitive but not available for routine diagnosis of the malaria parasite

Loop-mediated isothermal amplification (LAMP)