Lecture 15 - Travel Related Infections And NTDs Flashcards
What is a NTD (Neglected Tropical Disease)?
Diseases that are almost absent from the global health agenda
They get little funding, have stigma and associated social exclusion
What is the goal of the NTD Road Map?
To eliminate as many Neglected Tropical Diseases as possible
Why is a good history important when it comes to Neglected Tropical Diseases?
There are lots of travel related infections
Certain disease are specific to certain areas
Different strains of pathogen from different areas may be resistant to certain drugs
What information are you trying to establish where asking a patient:
“Where have you been/travelled to?”
What potential diseases are in that area
What information are you trying to establish where asking a patient:
“When were you last in that place?”
Evaluating the incubation time
What needs to be considered when you think a patient may have an NTD?
Where have they been?
When were they there?
How may they have acquired the infection
Any prophylaxis or vaccinations?
Anyone else in their group unwell?
What are the steps of the infection model?
Pathogen + Patient + Mechanism of infection = Infection
Management
Outcome
What must be considered about a patient ini the infection model?
Age group
Immune status
Drug use
Where have the been
Timeline
What are some potential mechanisms of infection of a NTD?
Food/water
Insect/tick bite
Swimming
Sexual contact
Animal contact
Recreational activities
What is carried out in the management phase of the infection model?
History taken
Examinations done
Investigations carried out
Treatment given (Specific and/or supportive treatment)
What is a common infection acquired via an animal bite?
Rabies
What is a common infection acquired via rodents?
Leptospirosis
What are 2 common infections acquired via a mosquito or insect bite?
Malaria
Dengue
What is a common infection acquired via a Tick bite?
Rickettsia
What are 2 common infections acquired from freshwater?
Schistosomiasis
Leptospirosis
What is a common infection acquired via undercooked meat/fish?
Salmonella
E. Coli
What is a Rickettsia/spirochaete?
Small non motile gram negative bacteria usually spread by ticks
What are the 5 species of malaria that affect humans?
Plasmodium falciparum
Plasmodium vivax
Plasmodium ovale
Plasmodium malariae
Plasmodium knowlesi
Which is the most common and most severe species of malaria?
Plasmodium falciparum
What are the 2 less severe and relapsing species of malaria compared to plasmodium falciparum?
Plasmodium vivax
Plasmodium ovale
What is special about the transmission of Plasmodium knowlesi?
From macaque monkeys (ZOONOTIC Transfer)
What is the general life cycle of Plasmodium Falciparum?
Female mosquito bites
Sporozites travel to liver cells
Form schizont
Liver cells burst releasing Merozoites
Merozoites infect red blood cells
Form schizonts
Then burst RBCs releasing more Merozoites (cycle continues
What can happen to a Plasmodium Falciparums Merozoite once its burst form a RBC?
Renter cycle by infecting another RBC
Or
Form Gametocyte which gets picked up by mosquito and forms more sporozoites
What is the vector for Malaria?
Female Anopheles mosquito
What are the signs and symptoms of Malaria?
Fever
Chills
Headache
Confusion
Seizures
Jaundice
Haemoglobinuria
What investigations would be done for suspected malaria?
FBC
U + E
Liver function test (AST + ALT)
CXR (Chest X-ray)
CT head
What can be done to manage malaria?
Remove the mosquito (Bed nets, avoid still lakes and sanitation facilities)
Drugs: Artesunate, Quinine and Doxycylcine
What drug is given for liver related Malaria?
Primaquine
Why may you not be able to administer Primaquine to a patient? (What condition might they have)
May have Glucose-6-Phosphate-Dehydrogenase Deficiency
Why can you not give Primaquine or Chloroquine to a patient with G6PDH deficiency?
Primaquine is an exogenous oxidant
People with G6PDH deficiency are vulnerable to oxidative stress
G6DPH needed in the Pentose phosphate pathway
No G6DPH means no NADPH made which is needed to regenerate GSH from GSSG
GSH = Important defence against oxidising damage
Why can G6PD deficiency lead to Haemolytic Anaemia?
RBCs wont have the protection from GSH so will likely be broken down
What is the mechanism of infection of Enteric Fever/Typhoid fever?
Faecal oral from contaminated food/water
What are some virulence factors of enteric/typhoid fever?
Low infectious dose
Survives gastric acid
Resides within macrophages
Fimbriae adhere to epithelium over ideal lymphoid tissue
Who is susceptible to enteric fever/typhoid fever?
Children
Travellers from Asian countries
What are the signs and symptoms of Enteric/Typhoid fever?
Systemic manifestation:
-Fever
-Headache
-Abdominal discomfort
-Dry cough
-Bradycardia
How can Typhoid/enteric fever be diagnosed?
Blood cultures
What are the treatment options for typhoid/enteric fever?
IV Ceftriaxone
Azithromycin
Ciprofloxacin
What are some preventative methods for typhoid/enteric fever?
Vaccination
Good food + water hygiene
What might an individual with malaria present with?
Tachycardia
Low BP
Low O2 sats
Mild confusion
Bite/puncture marks
Hepatosplenomegaly
Vomiting and nausea
When does a person experience the symptoms of malaria?
When merozoites are destroying the red blood cells
What May Malaria go onto cause in an infected individual?
Haemolytic anaemia
What are the signs and symptoms of Haemolytic anaemia?
Pallor
Jaundice
Dark coloured urine (Hb in the Urine)
Weakness
Dizziness and confusion
Why can malaria lead to jaundice?
RBC destroyed by the malaria
Hb builds up so bilirubin builds up as the Hb gets broken down
When a blood test and blood film is taken, what will be seen with malaria?
Normocytic and normochromic anaemia
Thrombocytopenia
Elevated lactate dehydrogenase
As well as destroying RBCs how does Plasmodium falciparum cause damage?
Produces sticky protein
Coats surface of erythrocytes causing them to clump together
Occludes blood vessels leading to organ ischaemia
Why is Chloroquine not used for Plasmodium falciparum?
Widespread resistance to it
What does a doctor treat for if they cannot confirm the species of plasmodium in malaria?
Chloroquine-resistant plasmodium falciparum
What is Recrudescence? (Malaria)
The treatment didn’t kill of all the parasite so they have it again
What is relapse in terms of patients being cured from malaria?
All merozoites cleared
But dormant malaria in the liver
What is reinfection in terms of patients being cured from malaria?
A completely new case of the same disease so in this case malaria again
What causes Legionnaires disease?
Gram negative Legionella bacteria
How is Legionella pneumophilia transmitted?
Inhaling contaminated water droplets from the environment
What is the pathophysiology of Legionella pneumophilia infection (Legionnaires disease)?
Legionella pneumophilia invades macrophages in lungs and replicates inside them
What are the initial symptoms of Legionnaires disease?
Headaches
Muscle/chest pain
Chills
Fever (can be 40º or higher)
What could be some progressive symptoms of Legionnaires disease?
Cough (mucus maybe blood)
Shortness of breath
GI symptoms (nausea, vomitting and diarrhoea)
Mental changes
What is used to treat Legionnaires disease?
Carithromycin
What causes schistosomiasis?
Flatworm common in tropical areas
How is schistosomiasis contracted?
Unprotected skin contact from freshwater contaminated with the helminths released from snails
What are the symptoms of schistosomiasis?
Fever
Diarrhoea
Coughs
Rashes
Abdominal pain
Muscle and joint pain
Causes Chronic Inflammation
How is schistosomiasis diagnosed?
Egg found in a urine or stool sample
Blood test for antibodies
How is Acute Schistosomiasis treated?
Steroids = reduce inflammation
Praziquantel (Most effective once the worms have matured)
What is the causative organism for Typhoid fever (enteric fever)?
Salmonella typhi
What type of organism is Salmonella typhi?
Rod-shaped Gram negative bacteria
What type of organism causes Dengue?
Virus (4 different strains)
What transmits the Dengue virus?
Mosquitos
What may an individual present with if they have Dengue?
Intense headache
Fever
Muscle/joint pain
Widespread red rash
What is the treatment for Dengue?
NO TREATMENT
Usually self resolves
Can only treat symptoms (supportive treatment)
What are some supportive treatments for Dengue?
Paracetamol (analgesic + anti pyretic)
Plenty of water
What is the danger of re infection of Dengue?
Can progress to severe dengue or Dengue Haemorrhagic fever
What supportive treatments can be give to someone with Dengue haemorrhagic fever?
IV fluids
Oxygen therapy
Blood and platelet transfusions
What are the symptoms of Dengue Haemorrhagic fever?
Restlessness
Acute/sudden fever
Severe abdominal pain
Bleeding or bruising under the skin (petechiae)
Nosebleeds
Large drop in BP (shock)
What is a characteristic feature of the blood in Dengue Haemorrhagic fever?
Thrombocytopenia (low levels of platelets)
If giving painkillers to help with Dengue haemorrhagic fever what must you NEVER GIVE?
Why?
Aspirin
It’s an Anti platelet drug which will make the bleeding worse
