Vaccine Preventable Diseases - SP Flashcards
(38 cards)
1
Q
Infectious Disease in Global Health
A
- Single most important contributors to human morbidity and mortality throughout history
- Mortality has declined over past 150 years in high-income countries
- In low- and middle-income countries they remain issues of significance
2
Q
Role of poverty
A
- Malnutrition and micronutrient deficiencies associated with increased risk of sever morbidity and mortality
- Lack of education
- Poor access to clean drinking water
- Inability to dispose properly of human waste
- Household crowding
- Lack of access to health care
3
Q
Strategies to control infectious diseases
A
- Vector control (malaria, dengue, yellow fever, and onchocerciasis)
- Vaccinations (smallpox, measles, polio, neonatal tetanus, diphtheria, pertussis, tetanus, hepatitis B, meningococcal meningitis and yellow fever, human papilloma virus)
- Mass chemotherapy (some parasites)
- Improved sanitation and access to clean water(diarrheal diseases)
4
Q
Control
A
- Reduction of disease incidence, prevalence, morbidity or mortality to a locally acceptable level as a result of deliberate efforts;
- Continued intervention measures are required to maintain the reduction
- Malaria
- Neonatal tetanus
- Cholera
- TB
- Schistosomiasis
- Diarrheal disease
- ARI
- AIDS
- STIs
- Leprosy
5
Q
Elimination of disease
A
- Reduction to zero of the incidence of a specified disease in a defined geographic area as a result of deliberate efforts;
- Continued intervention measures are required
- Rabies
- Trachoma
6
Q
Elimination of infection
A
- Reduction to zero of the incidence of infection caused by a specific agent in a defined geographic area as a result of deliberate efforts;
- Continued measures to prevent reestablishment of transmission are required
- River blindness
7
Q
Eradication
A
- Permanent reduction to zero of a worldwide incidence of infection caused by a specific agent as a result of deliberate efforts;
- Intervention measures are no longer needed
- Polio
- Measles
- Guinea worm
8
Q
Extinction
A
- The specific infectious agent no longer exists in nature or in the laboratory
- Extinction of smallpox is possible, although concerns about use in bioterrorism prevent destruction of the last known stocks of the virus
- Smallpox
9
Q
Poliomyelitis
A
- 3 known serotypes (1, 2, and 3)
- Fecal-oral transmission
- Ingestion of virus leads to asymptomatic or mild, self-limiting infection and shedding of virus from throat to GI tract in most persons
- 1/100 to 1/850 develop symptomatic polio with or without paralysis
10
Q
Symptomatic Poliomyelitis
A
-Primarily affects 1 or both legs
-Of those developing paralysis:
~10% die acutely
~10%-15% permanently unable to walk
~10%-15% unable to walk normally
11
Q
Poliomyelitis: Initial symptoms
A
- Fever
- Fatigue
- Headache
- Vomiting
- Stiffness in neck
- Pain in limbs
- Paralysis (can cause total paralysis in a matter of hours)
- 5%-10% die due to respiratory paralysis
12
Q
Poliomyelitis: Epidemiology
A
- Mainly affects children under 5 years of age
- One in 200 infections leads to irreversible paralysis
- Cases decreased by over 99% since 1988
- 223 cases globally in 2012
- 2013 only 3 countries polio endemic: Afghanistan, Nigeria, Pakistan
13
Q
Poliomyelitis: Tx
A
- No cure
- Treatment entirely supportive
- Can only be prevented through multiple vaccination (series of 3) providing life-time protection
14
Q
Polio Immunizations
A
Killed injectable polio vaccine (IPV)
Live oral polio vaccine (OPV)
- Available since 1960s
- Extremely low cost ($0.02- $0.11/dose)
- Ease of administration
- Intestinal induced immunity prevents oral-fecal transmission
- Lower immunity in low- and middle-income countries
15
Q
Measles
A
- Caused by virus in the paramyxovirus family
- Grows in the cells that line back of throat and lungs
- Virus spread via respiratory route
- Easily transmitted and highly infectious
- In the absence of vaccine-induced immunity, virtually every child can be expected to develop measles if the virus is circulating in the community
16
Q
Measles: Transmission
A
- Spread by coughing and sneezing
- Close personal contact
- Direct contact with infected nasal or throat secretions
- Virus remains active and contagious in the air or on infected surfaces for up to 2 hours
- Can be transmitted by an infected person from 4 days prior to onset of rash to 4 days after rash erupts
17
Q
Measles: Symptoms
A
- Fever – begins ~ 10-12 days after exposure and last 4-7 days
- Cough
- Runny noes
- Red and watery eyes
- Malaise
- Small white spots inside the cheeks
- Early phase indistinguishable from other viral respiratory infections (first several days when most contagious)
- Characteristic rash appears after 7 to 14 days and spreads over 3 days, eventually to hands and feet
- Rash lasts 5-6 days, then fades
18
Q
Measles: Complication
A
Common: pneumonia, diarrhea, ear infection
Less Common: encephalitis, blindness
Measles in pregnancy: Higher risk for severe complication, Pregnancy may end in miscarriage or preterm delivery
Risk Factors: Younger age, Malnutrition (particularly vitamin A deficiency), HIV infection
Measles frequently leaves a child weakened and at increased risk of illness and death from other causes for a year or more after the acute episode
19
Q
Measles: Treatment
A
- Supportive care to avoid complications
- Good nutrition
- Adequate fluid intake
- Treatment of dehydration
- Antibiotics for secondary infections
- 2 doses of vitamin A supplements, given 24 hours apart (shown to reduce deaths by 50%)
20
Q
Measles: Epidemiology
A
-One of the leading causes of death among young children even though a safe and cost-effective vaccine is available
-Most mortality in children < 5
> 95% of measles deaths occur in low-income countries with weak health infrastructures
-Measles vaccination resulted in a 71% drop in measles deaths 200 – 2011 worldwide
-2011 about 84% of the world’s children received one dose of measles vaccine by their first birthday through routine health services
-Unvaccinated children are at highest risk
-Unvaccinated pregnant women also at risk
-Any non-immune person can become infected
-Still common in many developing countries, especially Africa and Asia
> 20 million affected each year
21
Q
Measles deaths in 2011
A
158,000 globally
~ 430 deaths every day
~18 deaths every hour
-Over 95% in countries with low per capita incomes and weal health infrastructures
-Outbreaks particularly deadly in countries experiencing or recovering from natural disaster or conflict due to:
-Damaged health infrastructure/interrupted immunization programs
-Overcrowding in residential camps
22
Q
Measles: Prevention
A
- Routine vaccination of children
- Mass immunization campaigns in countries with high case and death rates
- Often incorporated with rubella and/or mumps vaccines
-Barriers to eradication: Widespread disease, Often occurs in infants prior to age of first vaccination
23
Q
Diphtheria
A
- Caused by bacterium Coryne-bacterium diphtheriae
- Spread via respiratory route
- Toxin mediated
- In low- and middle-income countries can also cause (and be spread via) ulcerative skin lesions
- Complications: Infection of the nasopharynx that may cause breathing difficulties and death
24
Q
Diphtheria: Treatment
A
- Antibiotics: Erythromycin or penicillin for 14 days and post treatment cultures to confirm eradication
- Diphtheria antitoxin (rarely available in low- and middle-income countries
- Treatment recommended for patients with active disease and all close contacts
- Mortality rate 5-10% , > 20% in children under 5 and adults over 40
25
Diphtheria: Epidemiology
- Primarily a disease of childhood (< 12 years old)
- Infants become susceptible at age 6-12 months after transplacentally derived immunity wanes
- Recently shifted into adolescent and adult population (> 40) primarily due to incomplete immunization status
26
Diphtheria: 2011 global figures
- 4,887 reported cases
- Likely under diagnosed
- 83% estimated DTP3 coverage
- 24% of countries reached > 80% DTP3 coverage in all districts
- Because vaccination does not lead to elimination of carriage of C. diphtheriae from the nasopharynx, ongoing control requires high levels of vaccine coverage
27
Pertussis (Whooping Cough)
- Caused by bacterium Bordetella pertussis
- Spread via respiratory route
- Highly contagious
- Significant cause of morbidity and mortality in absence of high levels of coverage with vaccine
- Difficulty to distinguish from other respiratory infections
28
Pertussis (Whooping Cough): symptoms
- Incubation period of 6-20 days (usually 9-10)
- Followed by URI symptoms with cough
- After 1-2 weeks coughing paroxysms ending in characteristic whoop may develop
- Treatment may not be effective once symptoms develop
29
Tetanus
- Caused by anaerobic bacterium Clostridium tetanus
- Commonly found in GI tract of many domesticated animals (cows, sheep, and goats)
- Spores can remain viable for years-decades when deposited in soil
- When spores introduced into wound or other suitable environment they produce highly toxic neurotoxins as they grow
30
Tetanus: symptoms 7 treatments
- Painful stiffening and spasms of muscles (including jaw)
- Results in inability to suck or otherwise feed (particularly in newborn infants)
Tx: Supportive: -Muscle relaxants -IV fluids
Fatality rate very high: 80% to 90% in infants and newborns
31
Tetanus: Epidemiology
- In 1970s and 1980s 60/1,000 (6%) were developing neonatal tetanus in some low-income countries
- Primarily due to contamination of the umbilical stump
- Virtually all died
- Deaths due to neonatal tetanus accounted for ¼ - ¾ of all neonatal deaths and as much as ¼ of all infant mortality in these countries
32
Cholera
- Acute diarrheal disease that can kill within hours if left untreated
- Caused by ingestion of food or water contaminated with the bacterium Vibrio cholerae
- Incubation period – 2 hours to 5 days
- Extremely virulent in both children and adults
- Bacteria present in feces for 7-14 days after infection (even if asymptomatic)
33
Vibro Cholerae strains
- 01 and 0139 cause outbreaks
- 01 causes majority of outbreaks
- 0139 confined to South-East Asia
- Non-01 and non-0139 can cause mild diarrhea but do not generate epidemics
- New variant strains have been detected in parts of Asia and Africa
- New strains may cause more severe disease with higher fatality rates
34
Cholera: symptoms
~75% have no symptoms
-Among people with symptoms, 80% have mild or moderate symptoms
~20% develop acute watery diarrhea with severe dehydration
35
Cholera: Risk factors
- Low immunity
- Malnutrition
- Inadequate environmental management
- Peri-urban slums where basic infrastructure is not available
- Camps for internally displace people or refugees
- Consequence of disaster with disruption of water and sanitation systems
36
Cholera: Epidemiology
- Pandemics during 19th century killed millions of people across all continents
- Current pandemic started in South Asia in 1961
- Reached Africa in 1971
- Reached the Americas in 1991
- Now endemic in many countries
37
Cholera: Prevention and control
- Easily treatable
- Up to 80% can be treated successfully through prompt oral rehydration salts
- IV fluids for severe dehydration
- Appropriate antibiotics to diminish duration of diarrhea in severe cases
- Mass administration of antibiotics not recommended
- Important to ensure prompt access to treatment
- Safe water
- Proper sanitation
- Health education for improved hygiene
- Safe food handling
38
Oral cholera vaccines
- Two types of safe and effective oral cholera vaccines currently available
- Both have sustained protection of over 50% lasting for 2 years in endemic settings
- Both administered in 2 doses given between 7 days and 6 weeks apart
- WHO recommends vaccines in conjunction with control measures in endemic areas as well as areas at risk of outbreaks
