Communicable Diseases Flashcards
What are the initial symptoms of pertussis?
Cold-like symptoms
Runny nose
Watery eyes
Sneezing
Fever
Mild cough (that gets worse)
How is pertussis spread?
Droplets
What age group is in the most dangerous if they get pertussis?
Children <1yr
What is the incubation period of pertussis?
6-20 days
When are you infectious with pertussis?
From 6 days after exposure to 3 weeks after cough onset
How long are you ill with pertussis for?
2-3 months
What are the complications with pertussis?
Collapsed lung and/or pneumonia
Convulsions, permanent brain damage or death
Severe weight loss and dehydration due to vomiting
Sudden death (apnoeic attakcs)
How is polio transmitted?
Though contact with faeces or droplets of infected person
What is the incubation period of polio?
3-21 days
What proportion of polio will become paralytic?
<1%
How long after illness does paralytic polio develop?
1-10 days
Why was the live polio vaccine replaced by an inactivated one?
Virus sometimes (rarely) reverts back to wildtype
What are the symptoms of measles?
Runny nose
Cough
Red and watery eyes
Small white spots inside the cheeks
Slight raised rash
Loss of appetite and loose stools
What age group is measles most common in?
1-4 year olds
How is measles spread?
Droplets
What is the incubation period of measles?
7-18 days
When are you infectious with measles?
From beginning of first symptoms to four days after the appearance of the rash
What proportion of measles cases develop complications?
30%
What are the complications of measles?
Severe diarrhoea
Pneumonia
Otitis media
Convulsions
Encephalitis
Subacute sclerosing panencephalitis
Death
How is HIV spread?
Sexual
IV-drug use
Blood transfusion
Mother-child (birth or breast milk)
What are the families of arbovirus?
Mosquitobourne
Tickbourne
Licebourne
What is the main issue with arboviruses?
They’re routinely untreatable
What are the reasons for the emergence and re-emergence of arboviruses and other exotic viruses?
Global warming
New vector species
Introduction of new species
Human interference with ecosystems
Extensive and rapid human travel
What are some examples of ‘common’ arboviruses?
Rift valley fever
Crimean-Congo haemorrhagic fever
West Nile virus
Dengue
Zika
What infectious diseases have been eradicated?
Smallpox and yellow fever
What % of deaths were caused by infection in 2010?
3%
What are the 5 infectious diseases in LICs?
Lower respiratory tract infection
HIV/AIDS
Diarrhoea
Malaria
TB
Why is the geographic distribution of arboviruses so broad?
Transmitted by birds and other such things which travel big distances (and therefore spread disease large distances
What are some reasons why life expectancy has increased?
Childhood immunisations
Heart disease treatment
Antibiotics
What % of deaths were caused by infection in 1910 and 2010?
1910 - 46%
2010 - 3%
What are the biological reasons vaccines dont exist?
Mutations
Evolution of protective mechanisms
Integration into the host genome
Dormancy in immune privilege sites
Strain variation beyond immunological memory
What new and emerging infections cause vaccines to not exist?
Increasing zoonotic infections
Infections that only infect LMICs are of little commercial interest
What commercial reasons are there for vaccines not existing?
Vaccines are expensive and complicated to develop
LMIC problems are not commercially attractive
What logistical reasons prevent vaccines from existing?
Limited infrastructure in developing countries
The cold chain
Political/religious intervention
What are vaccine investment disincentives?
High development costs
Demand for new vaccines at lowest prices
What % of the worlds population depends on plants to treat illnesses?
75%
How many deaths/year are from 6 major vaccine preventable diseases?
4.25 million
What are the WHO priorities in terms of vaccines?
Reduce cost of vaccines and introduce more vaccines
Avoid needle use
Simplify immunisation regimes
Remove the need for a cold chain
What infections is post-exposure prophylaxis usually used for?
Rabies
Tetanus
HIV
Hep A, B and C
Ebola
What are the advantages of using passive immunisation?
Immediate protection
Effective in healthy and immunocompromised patients
More consistent response than vaccines
What are the disadvantages of passive immunisation?
Quality control and uniformity of product
Safety of production system
Repeated administration -> serum sickness
Cost and availability
Short-lived protection
Escape mutants
What are the two types of rabies?
Furious and paralytic
What happens in furious rabies?
Hyperactivity and excited behaviour
Fear of water and sometimes air movement
After a few days, death occured by cardio-respiratory arrest
What happens in paralytic rabies?
Gradual muscle paralysis starting at the site of the bite
A coma slowly develops and eventually death
What animal controls can be used to stop rabies?
Sterilisation
Euthanisation (doesnt work)
Vaccination
What human controls can be used in rabies control?
Education
Post-exposure prophylaxis
Vaccines
What are some issues with using rabies immunoglobulin?
Unaffordability
Limited availability
Batch-to-batch variation
Contamination with adventitious agents
Two tier system for product availability
Ethical issues
What are the two cycles of an arbovirus?
Man - arthropod - man
Animal - arthropod - man
Where is the reservoir in the man - arthropod - man cycle?
Either in man or arthropod vector
Where is the reservoir in the animal - arthropod - man cycle?
Animals
How long is the incubation for dengue?
2-7 days
Where is dengue found?
Generally in the 10 degree isotherms
What are the symptoms of classic dengue?
High fever
Severe muscle pains
Erythematosus rash
Generalised lymphadenopathy
Moderately enlarged liver
Profound leukopenia
When are you most likely to develop severe dengue?
Between 3-6 days
What are the symptoms of severe dengue?
Haemorrhagic fever/ dengue shock syndrome
Increased capillary permeability -> shock
Increased bleeding, petechia haemorrhages etc
How do you diagnose severe dengue?
Positive tourniquet test
Spontaneous haemorrhage
Thrombocytopenia
Increase in haematocrit
What are the two groups most at risk of developing severe dengue?
Infants with declining levels of maternal antibodies
Children with previous dengue infection
How do you treat dengue?
Supportive
Paracetamol
Tepid sponging for fever
Fluid replacement where necessary
How can you prevent/control dengue?
Vaccine
Vector control (insecticide spraying, mosquito nets/ screens, Wolbachia and GM mosquitos)
What is the incubation of chikungunya?
2-7 days
What are the symptoms of chikungunya?
Fever ->
Itchy maculopapular rash
Poly arthralgia
Is polyarthralgia found in all chikungunya cases?
No (30-90%)
Where does polyarthralgia affect in chikungunya?
Joints of wrist, ankles, fingers
What is the treatment for chikungunya?
Bed rest
Fluids
Paracetomol (NOT ASPIRIN)
Chloroquine for persistent joint pain
How long does chikungunya last?
</= week
How is Zika virus transmitted?
Via a vector (mainly aedes aegypti)
Direct human to human (in utero, perinatal- breastfeeding, transfusion, sexual)
What is the incubation period of zika?
<7 days
What proportion of Zika infection is asymptomatic?
80%
How long does zika illness last for?
7 days
What are the symptoms of Zika?
Headaches
Painful or red eyes
Fever
Joint pain
Microcephaly
Guillain-Barré syndrome
(Very rare = meningoencephalitis and acute myelitis)
How can you diagnose zika?
Specific RT-PCR for RNA
Specific IgM and IgG ELISAs
Neutralisation tests for 4-fold increase in titers
How do you treat zika?
Repellants/screens/residual spraying/breeding sites
Postpone travel to endemic areas
Postpone pregnancy
Safe sex
What is the incubation period of yellow fever?
3-6 days
What are the normal yellow fever symptoms?
Fever
Headaches
Chills
Back pain
Muscle pain
Nausea
Vomiting
What proportion of yellow fever patients go on to develop severe yellow fever?
15%
What are the symptoms of severe yellow fever?
Reoccurring fever
Jaundice and abdominal pain
Bleeding and vomiting blood
How to control yellow fever?
Vaccine - single dose
How can you control arboviruses?
Insecticides
Personal and household protection (clothes/repellants/nets/window and door screens/covering water sources)
Spraying
Vaccination
How many people died from Diarrhoeal disease globally in 2019?
1.5 million
What proportion of deaths from Diarrhoeal disease were children <5?
1/3
How much has the global <5 mortality rate for Diarrhoeal disease decreased?
56%
Where is mortality from Diarrhoeal disease generally?
Africa and SE Asia
How much has the global neonatal mortality rate for Diarrhoeal disease decreased?
49%
Which group of children are most at risk from dying from Diarrhoeal disease?
Malnourished
Impaired immunity
HIV+
What is a social demographic index?
Index of income/capita, educational achievement and fertility rates
How many individuals worldwide lack access to clean drinking water?
780 million
In LMICs, how many episodes of diarrhoea do children <3yrs experience per year?
3
How many people worldwide lack improved sanitation?
2.5 billion
What is the definition of diarrhoea?
Water or liquid stools with an increase in stool frequency and weight above 200g/day for more than two days
What are the clinical consequences of Diarrhoeal disease?
Severe dehydration
Excessive fluid and electrolyte loss
Hypovolemia
Hypokalaemia
Organ failure
Long term morbidity and reduced growth
What microorganisms cause watery diarrhoea?
Norovirus
Cholera
E.coli enteritis
What microorganisms cause dysentery?
Shigellosis
Amoebiasis
What causes persistent diarrhoea?
Usually unknown but associated with immunosuppression
What are complications of watery diarrhoea?
Dehydration
Electrolyte imbalances
Tetany
Convulsions
Hypoglycaemia
Renal failure
What are the complications of dysentery?
Electrolyte imbalances
Convulsions
Haemolytic uremia syndrome
Toxic mega colon
Protein losing enteropathy
Arthritis
Perforation
Can you get non-infectious causes of diarrhoea?
Yes
What are some infectious causes of diarrhoea?
Rotavirus (mainly)
Cholera
Shigella
Adenovirus
Campylobacter
Norovirus
Protists
How is diarrhoea transmitted?
Fecal-oral
Some viruses can be transmitted through air
Nosocomial is possible
Shigella mainly person-person
What age group is cholera most common in?
2 years and above
Uncommon in very young infants
What age group is shigellosis most common in?
Children <5 yrs
What age group is rotavirus most common in?
Young infants and children from 1-2yrs
What age group is E.coli most common in?
Can occur at any age
What age group is amoebiasis most common in?
Adults
Which Diarrhoeal microbes can be sexually transmitted?
Amoebiasis
Giardiasis
Shigellosis
E.coli
What is the epidemiology of giardiasis?
Distribution similar to global distribution of Diarrhoeal disease
Poor sanitation and water infrastructure increases risk
High prevalence in children in the developing world
What are the high risk groups in HICs of entamoeba histolytica?
Queer males
Travellers
Recent immigrants
Institutionalised populations
Where is there higher incidence of entamoeba histolytica?
Developing countries
Where is typhoid endemic?
Asia
Africa
Latin America
Where are the highest death rates of rotavirus?
Afghanistan, chad, Somalia, Burundi
How can you prevent diarrhoea?
Breast feeding
WASH
Vaccination
Zinc supplements
How can you treat diarrhoea?
Rehydration
Antibiotics (maybe)
Maintain breastfeeding
Protein (After shigellosis)
Restore trace elements
What is the aim of the integrated global action plan for the prevention and control of pneumonia and diarrhoea?
Integrated approach to decrease incidence of severe pneumonia and diarrhoea
End preventable childhood deaths from pneumonia and diarrhoea
What are the strategies used in the integrated global action plan for the prevention and control of pneumonia and diarrhoea?
Protect (vitamin A supplementation, breastfeeding promotion and support and adequate complementary feeding)
Prevent (vaccination, WASH, decreasing indoor pollution)
Treat (improved care seeking behaviour and referral, ORT, continued feeding, antibiotics for pneumonia, oxygen therapy)
