28 Vector-borne infections - protozoa Flashcards by B M

Which protozoa are transmitted by arthropods?

Malaria

Trypanosomiasis

Leishmaniasis

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Plasmodium transmitted by female anopheles mosquito. Can also be transmitted vertically, and via blood transfusion

Approx 200 million cases/ year.

What are the names of plasmodium species?

Falciparum

Vivax

Malariae

Ovale

Knowlesi

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What is geographic spread of these species of plasmodium?

Falciparum

Vivax

Malariae

Ovale

Knowlesi

Falciparum - tropics

Vivax - India/ SE Asia, SA, NE Africa

Malariae - tropics

Ovale - tropical Africa

Knowlesi - SE Asia

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Which plasmodium species have tertian/ quartan fever?

tertian fever - every 3rd day
quartan fever - every 4th day

Tertian -
falciparum
vivax
ovale

Quartan -
malariae

tertian have asexual reproduction every 48 hours
quartan have asexual reproduction every 72 hours

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Why is there a lack of P vivax in West Africa?

Plasmodium binds to red blood cell Duffy antigen

high prevalence of Duffy-negative people in West Africa

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What conditions provide some protection from malaria>

Duffy antigen negative
sickle cell
beta-thalassaemia
G6PD

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What is life cycle of plasmodium?

not in mosquito

Sporozoites from saliva injected into new host

Move from blood to liver. Two weeks later mature into pre-erythrocytic schizonts

hepatocyte ruptures, releasing merozoites. They enter RBC, where they undergo asexual reproduction. Some species (vivax/ ovale) can have latent hypnozoites

merozoite in RBC matures ring form, trophozoite, and schizont. Which ruptures and releases merozoites into bloodstream (completing cycle)

some merozoites undergo sexual stage, and produce gaemtocytes, which are taken up by new anopheles mosquito during feeding

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What is life cycle of plasmodium?

in mosquito

gametocytes taken up by anopheles mosquito during feeding

once inside mosquito gut, gametocytes fertilise to form zygoe, which invades gut mucosa, and forms oocyst

oocyst produces produces sporozoites which are released and migrate to salivary glands of insect

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What are symptoms of malaria?

Fever
headache
myalgia

can then develop multi-organ failure as parasatised red cells sequester in capillaries, causing endothelial dysfunction -

cerebral disease
jaundice
anaemia
hepatosplenomegaly

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What is incubation period of malaria?

Between 6-40 days
usually 9-14 days most common time to present

Can present up to 6 months after travel event

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What are clinical manifestations of severe malaria?

reduced GCS <11
convulsions
respiratory distress
prostration
shock
jaundice

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What are biochemical manifestations of severe malaria?

abnormal coagulation
anaemia
hypoglycaemia <2.2
metabolic acidosis
renal impairment
parasitaemia >10%

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People living in endemic plasmodium area, if they survive first infection, they develop immunity, and subsequent infections are not as severe.

If they move to UK, how long before they lose immunity?

approx 1 year out of endemic area will reduce immunity

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How to diagnose malaria?

Lateral flow test - rapid antigen test

thick/ thin blood film - 3x sets (admission/ 24 hours/ 48 hours). If from endemic country, having parasite in bloodstream, does not mean it is always causing disease. If blood film negative, and high suspicion, may need biopsy of tissue

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What is treatment of -

uncomplicated falciparum

complicated falciparum (>2% parasitaemia)

PO co-artem (Artemetherelumefantrine (Riamet) is the drug of choice for 3 days
dihydroartemisinin-piperaquine (Eurartesim) is an alternative for 3 days

Alternatives -

Quinine and doxycycline 5-7 days
atovaquone- proguanil (Malarone) 5-7 days

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What is treatment of -

vivax/ ovale/ knowlesi/ malariae

co-artem or chloroquine

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How to remove hypnozoites from liver? (vivax/ ovale)

Radical clearance

primaquine 14 days

contraindicate in G6PD deficiency

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How to prevent/ reduce malaria spread?

Mass chemotherapy

insecticide treated nets

indoor residual spraying

removal of stagnant water

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Suspected malaria. What details are important in travel history?

Must notify public health with positive cases

Country and area of travel.

Stopovers and other countries transited through.

Date of return.

Type of travel and activities while abroad — people returning from visiting friends and family in endemic areas are more at risk of malaria than tourists.

Prophylaxis taken

Vaccinations e.g YF

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What are important differential diagnoses of malaria?

VHF - ebola/ marburg/ lassa

dengue

typhoid

leptospirosis

babesiosis - anaemia

African Trypanosomiasis

Could be simple bacterial sepsis. But if high risk/ travel, do not miss malaria

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Which malaria patients need to be admitted?

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Is suspected of having severe or complicated malaria.
Is suspected of having falciparum malaria.
Is a pregnant woman.
Is a child.
Is older than 65 years of age.

Non-falciparum malaria can be managed as outpatient, if observed for 8 hours after starting treatment

What is treatment of -

complicated falciparum (severe)

> 2% parasitaemia indicates IV therapy required

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IV artesunate until manage oral/ parasite count reduced
if not available, start IV quinine until artesunate sourced
manage in HDU/ ITU

What is treatment of malaria in pregnancy?

Increases risk of miscarriage

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Co-artem 2nd/3rd trimester

Quinine + clindamicin all 3 trimesters

Where is resistance emerging in malaria treatment?

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SE Asia
SA

chloroquine resistance

What are options for malaria prophylaxis?

Doxycycline Mefloquine Atovaquone-proguanil (malarone) Chloroquine - widespread resistance

What are options for malaria prophylaxis in pregnancy?

Advise avoid travel to high risk area Mefloquine - can be used all trimesters, although less data in first trimester Atovaquone-proguanil - lack of data, avoid if possible Doxycycline - definitely avoid first trimester. Can use in 2nd/3rd if very high risk of malaria outweighs contraindications

What do these terms mean? causal prophylaxis suppressive prophylaxis

Causal prophylaxis - active against liver stage (not hyponozoites), preventing release and infection of RBC. Take for 7 days after returning. Atovaquone-proguanil Suppressive prophylaxis - active against red blood cell stages. Take for 28 days after returning. Chloroquine, mefloquine, doxycycline

What are contraindications to chloroquine? If on hydroxychloroquine for rheumatic disease, can continue hydroxychloroquine without swapping

If resistance present epilepsy psoriasis myasthenia gravis amiodarone interaction

What are contraindications to doxycycline?

pregnancy children <12 as acidic preparation, can cause severe oesophagitis/ gastritis

When is emergence malaria standby treatment provided for travellers? What are drug options? including pregnancy

If going to be >24 hours away from medical assistance Artemther-lumefatrine or atovaquone-proguanil or quinine + clindamicin (pregnancy)

Female on malaria prophylaxis, planning to become pregnant. How long should anti-malarials be stopped for? Mefloquine Doxycycline Atovaquone-proguanil

Mefloquine: 3 months Doxycycline: 1 week Atovaquone/proguanil: 2 weeks

Patient with epilepsy travelling to malaria country. What are options?

Doxycycline or atovaquone-proguanil mefloquine/ chloroquine unsuitable

Patient with G6PD deficiency travelling to malaria country. What are options?

Avoid choroquine doxycycline/ mefloquine/ atovaquone-proguanil

When must these malaria prophlaxis drugs be started prior to travel? Doxycycline atovaquno-proguanil chloroquine mefloquine

Doxycycline or atovaquone-proguanil - 2 days before Chloroquine - 1 week before mefloquine - 2-3 weeks before (to ensure tolerance).

What are three species of trypanosoma?

African trypanosomiasis - Trypanosoma brucei gambiense (West) - 97% African cases Trypanosoma brucei rhodesiense (East) South American trypanosomiasis - Trypanosoma cruzi

African trypanosomiasis what is vector?

tsetse fly reservoir of trypanosomes in wildlife and cattle flies feed during daylight hours

What is clinical presentation of african trypanosomiasis?

following insect bite, widespread lymphadenopathy occurs. Enlarged cervical lymph nodes is known as Winterbottom's sign ``` fever splenomegaly myocardial involvement headache behavioural change - sleeping sickness, which leads to death ``` Even after treatment, can be left with permanent neurological disability

How does african trypanosomiasis evade host immune system?

Antigenic variation - switches between 900 different antigens on surface

How to diagnose african trypanosomiasis?

microscopy of blood/ CSF/ lymph node for parasites antitrypanosomal antibody - mostly only useful for screening populations

What is treatment of african trypanosomiasis

Suramin IV followed by melarsoprol IV if CNS involvement West African - Pentamidine IV Nifurtimox orally + eflornithine IV if CNS involvement

What is vector of South American trypanosomiasis?

reduviid bug - feeds on host, and excretes faeces. Host rubs trypanosomes into wound/ mucosa inhabit poor housing in rural areas most mammals can act as reservoir for infection can also be transmitted via contaminated food, blood donors

What are symptoms of South American trypanosomiasis?

Nodular lesion at inoculation site Swelling eyelid - Romanas sign fever GI - megaoesophagus/ megacolon Cardiac - myocarditis

how to diagnose South American trypanosomiasis?

Blood film PCR serology can perform PCR on reduviid bug stool

What is treatment for South American trypanosomiasis?

benznidazole oral or | nifurtimox oral

What is vector of leishmaniasis? Leishmaniasis either multiplies in skin (cutaenous) or in spleen/ liver/ bone marrow (visceral leishmaniasis)

sandflies dogs can act as important reservoirs

Which species cause cutaneous leishmaniasis?

L major L tropica L mexicana L braziliensis

Which species cause visceral leishmaniasis? also known as kala-azar

L donovani L infantum L chagasi

Visceral leishmaniasis is fatal in 90% cases What are symptoms?

Develops slowly fever weight loss hepatosplenomegalt

What are symptoms of cutaneous leishmaniasis?

Small papule develops into large ulcer. Can then heal with considerable scarring

How to diagnose leishmaniasis?

Microscopy of splenic aspirate/ bone marrow/ skin PCR serology

What is treatment of cutaneous leishmaniasis?

local injection of sodium stibogluconate

What is treatment of visceral leishmaniasis?

amphotericin B IV or | sodium stibogluconate IV

28 Vector-borne infections - protozoa Flashcards

(52 cards)