WEEK 10 - Tropical Diseases and Chemoprophylaxis Flashcards
Explain how factors like: Geography, Urbanisation, Social inequalities and Conflict influence tropical disease spread and contribute to NTD
NTD - Neglected tropical disease
Geography / Climate:
- Tropical disease thrive in high humidity, temp., and warmth
- esp. vector-borne disease
Acsess to Healthcare:
- Tropical disease are common in low-income countries
- Have limited access to healthcare, water and proper sanitation
Urbaninisation:
- Overcrowded living conditions
Poor sanitation:
- ↑ spread of tropical disease
- Inadequate sewage systems
- Contaminated water sources
Tropical disease affects tropical and subtropical areas
What are the 4 causes of tropical disease
- Vector-borne disease
- diseases transmitted by insects e.g. mosquitos, flies, ticks
- Protozal Infections
- disease caused by protoza
- Bacterial Disease
- Helminthic Infections
- caused by parasitic worm
List 5 examples of tropical diseases
ALL disease is included in PFP exam but NOT integrated
- Dengue
- Yellow fever
- Cholera
- Typhoid fever
- Malaria
NOTE:
- Hard to diagnose as they present like many other conditions = delayed treatment
= ↑ complication risk = ↑ mortality risk
How do we control + prevent the spread of tropical disease
- Vector control
- ↓ populations of disease-carrying insects
- use insecticides - Vaccinations
- Improved sanitation
- access to clean water, imrpoved hygiene - Surveillance and early detectiion
- monitor disease outbreak, notify GOV
- provide quick treatment to prevent spread - Health education
- health campaigns for prevention + seeking help
What is the cause of Malaria
INTEGRATED focues ONLY on Malaria
Plasmodium (a protazoan parasite)
5 Plasmodium Species:
1. Plasmodium falciparum – most deadliest
- most commonly seen
- causes many complications
2. Plasmodium vivax – recurring malaria, Asia and Latin America
3. Plasmodium ovale – milder, recurring malaria
4. Plasmodium malariae –chronic often asymptomatic malaria
5. Plasmodium knowlesi –primarily Southeast Asia, can cause severe illness
Describe the transmission of Malaria
Plasmodium infects liver cells and RBC
ROUTE: Vector to Human
- also be transmitted via shared needles, blood transfusion or vertically
- Plasmodium parasite targets anopheles mosquitos
- malaria reproduces, producing sporozites
- virus is transmitted to humans as mosquitos feed on human blood - Infected mosquito bites human + injects parasitic sporozites into bloodstream
- Within 30 min. sporozites travel to liver + are absorbed into hepatocytes
- where they mature + replicate
- hepatocyte bursts - Mature sporozites (merozites) leave liver, enter bloodstream + invade RBC
- further replicate + differentiate = gametes formed - Invasion causes RBC to burst
- causes symtpoms e.g. fever - Infection cycle continues:
- An un-infected mosquito bites an infected human and uptakes the parasite (gamate) from blood
- Parasite develops in mosquito
- Mosquito becomes infected + infects another human host
- An un-infected mosquito bites an infected human and uptakes the parasite (gamate) from blood
Explain the Malaria life cycle
Life cycle requires BOTH humans and mosquitos
1st phase = in humans
- Asexual reproduction phase (sporozites replicates in hepatocytes)
2nd phase = in mosquitos
- Sexual reproduction phase
- plasmodium parasite has a sexual phase in the anopheles mosquito
- Mosquito takes up gametes from human blood = allows sexual reproduction
- Malaria reproduces in mosquito, producing sporozites
- Mosquito host insect-borne phase
What are the symptoms of Malaria and how is it diagnosed
SYMPTOMS:
- High fever, severe chills, sweating
- Headache
- Fatigue
- Anaemia
- due to liver being affected
- Muscle aches
- Abdominal discomfort
- GI issues e.g. diarrhoea, constipation
- N&V
- Seizures, coma
- Jaundice
- Respiratory distress
- Pulmonary oedema
DIAGNOSIS:
- Blood tests
- hypoglycaemia, acidsosis, severe anaemia
- reveal presence of parasite + RBC destruction
What are the challenges with Malaria treatment
- Early stages of the human infected-parasitic stage can remain dormant in hepatocytes for years
- Dormant hepatocytes cane be reactivated without having to be bitten again by mosquito
- Dormant cells make it difficult to eradicate malaria completely
What is the treatment for Malaria
inc. Severe infection in pregnancy
UncomplicatedP. falciparum:
(asymptomatic, not a child / pregnant, have impairment)
1. Artemether with lumefantrine
- if unavailable oral quinine or atovaquone with proguanil
2. Quinine
- highly effective but poorly tolerated (bad SE)
- in combination with one other drug [oral doxycycline or clindamycin]
Severe or complicated P. falciparum:
(child, pregnant, symptoms)
1. HDU or ICU management
2. Immediate treatment
- IV Artesunate (min 24 hours) and step down to oral combination artemisinin when improved
- Alternative: oral quinine + doxy
3. Anti-emetics (for N&V)
Infection by P.falciparum in pregnancy:
- A MEDICAL EMERGENCY + requires HOSPITAL ADMISSION
List the 3 chemoprophylaxis / prevention options for malaria
- Atovaquone-proguanil (Malarone)
- Start 1-2 days before travel
- Taken once daily, before travel, during stay and for 7 days after leaving
- ADRs: GU upset, headache
- Most commonly used, has least SE - Doxycycline
- Start 1-2 days before travel
- Taken once daily, before travel, during and for 4 wees after leaving
- NOT SUITABLE: child and pregnancy
- ADRs: GI upset, sun sensitivity - Mefloquinine (Larim)
- Start 1-2 weeks before travel
- Taken once weekly, before travel and 4 weeks after leavinf
- NOT SUITABLE: pregancy
- ADRs: anxiety, depression, vivid dreams, nightmares
NOTE:
- Not 100% effective = BITE PREVENTION is KEY
Malaria: Special Patient Groups
What risks are associated with malaria in children + pregnancy
Children:
- Severe anaemia
- Enlarged liver and spleen
- Hypoglycaemia (low sugar levels)
- Recurrent infections
Pregnant Women:
(have an ↑ risk of being bit as their blood is more attractive to mosquitos)
- Premature labour
- Still birth / infant mortality
- Low birth weight (malaria causes restrictions to growth)
- Congenital malaria, foetal distress
- Maternal anaemia, haemorrhage
- Hypoglycaemia
- Acute pulmonary oedema
- ↑ risk of severe infection
- ↑ risk of recurrence (P.falciparum can remain in placenta)
What advice is given to individuals going to high-risk areas
- Take chemoprophylaxis
- Bite prevention
- as chemoprophylaxis is not 100% effecive
- use 20-50% deet repellent on exposed skin
- use mosquito nets covered in insecticides
- spray houses with insecticide
- wear longer clothing (esp. at night)
- avoid times of day mosquitos are most active
Malaria Vaccine INFO
Has been developed + trialled
- Only given to children (given in 4 doses)
- R21 = most effective vaccine
- Vaccine ↓ malaria cases + prevents seasonal malaria
- HOWEVER vaccine does NOT give life-long immunity
- may need boosters or annual vaccines
- doesnt completely eradicate disease
MoA:
- Causes synthesis of malarial antigen, elicits rapid immune system response
- Given in combinaion with adjuvant = stimulates stronger response
Describe the cause, transmission, signs and symptoms of Dengue
CAUSE: Viral
TRANSMISSION: Mosquito bite
SYMPTOMS:
Majority cases are asymptomatic or mild
- Fever
- Severe headache
- Severe abdominal pain
- Eye pain, swollen glands, muscle and joint pain, weakness
- Nausea and vomitting (N&V)
- Rash
- Breathing problems
- Cold skin
- Blood in vomit / stool
- Bleeding gums / nose
Appear 4-10 days after infection
Last 2-7 days
