Brucellosis, meloidosis, whooping cough, legionnairres Flashcards

Question

Pertussis • Pertussis is a very contagious respiratory infection commonly known as ‘———-’. • It is caused by the bacterium-——— • It was one of the most common ——— disease world wide before vaccines became widely available • In developing countries, the average case fatality rate (CFR) for pertussis has been estimated at almost —% in infants aged <— year and at —% in children aged — to —years • Large scale ——— programmes were associated with a steep decline in the number of pertussis cases and deaths in children • Despite high vaccination coverage (in the year—-, —% coverage with — doses of a pertussis containing vaccine), pertussis remains ——— in all countries and continues to be a public health concern

Answer 1

Pertussis (whooping cough) • Pertussis is a very contagious respiratory infection commonly known as ‘whooping cough’. • It is caused by the bacterium- Bordetella pertussis • It was one of the most common childhood disease world wide before vaccines became widely available • In developing countries, the average case fatality rate (CFR) for pertussis has been estimated at almost 4% in infants aged <1 year and at 1% in children aged 1–4 years • Large scale vaccination programmes were associated with a steep decline in the number of pertussis cases and deaths in children • Despite high vaccination coverage (in 2014, 86% coverage with 3 doses of a pertussis containing vaccine), pertussis remains endemic in all countries and continues to be a public health concern

Answer 2

Epidemiology of Pertussis Mode of transmission ■ Person to person via – Aerosolized droplets from cough or sneeze – Direct contact with secretions from respiratory tract of infectious person ■ 80% - secondary attack rate ■ Older children and adults are important sources of disease for infants and young children ■ Infants <12 months of age greatest risk for complications and death

Answer 3

Spread • Close person to person contact via aerosolized droplets from respiratory secretions of patients with disease • 90% of nonimmune household contacts acquire the disease • Adolescents and adults (27% of reported cases in 2004) are the major source of infection in unvaccinated children • Infants and young children are infected by older siblings who have mild to asymptomatic disease (43% of reported cases)

Answer 4

Clinical presentation • Mostly childhood disease • Incubation period of 9–10 day • Patients develop catarrhal symptoms, including cough with characteristic “whoop” • Cough is particularly severe at night and frequently followed by vomiting • In very young infants, pertussis may initially present as apnea and cyanosis • In previously immunized adolescents and adults, a persistent cough may be the only manifestation, without the characteristic “whoop”

Answer 5

Clinical presentation • Pertussis is a 6-week disease divided into catarrhal, paroxysmal, and convalescent stages, each lasting from 1-2 weeks. • Older children, adolescents, and adults may not exhibit distinct stages. Symptoms in these patients include uninterrupted coughing, feelings of suffocation or strangulation, and headaches • The cough can last for 6-10 weeks. It has been called the “100 day cough.” • How long a person is ill depends on age, other health conditions, and whether antibiotic treatment is given in the early stage of illness.

Answer 6

Pertussis Laboratory Testing 1.) Culture Specimen: NP Swabs or aspirates Advantages:•Gold standard •100% Specific Disadvantages:•Relativelv insensitive •Difficult to isolate •Most successful during the catarrhal stage •Takes 7-10 days to get the result 2.) PCR Specimen: NP Swabs or aspirates Advantages: Results available quickly Disadvantages:- Sensitivity & specificity Varies -•Calcium alginate swabs cannot be used to collect NP swabs for PCR Comments: Use with culture 3.) DFA Specimen: NP Swab Advantages: Rapid results Disadvantages: •Not confirmatory No use for surveillance Comment: Use with culture and/or PCR 4.) serology Specimen: blood Advantages: Disadvantages: -No standardized test available -No use for Surveillance Comment: Use with culture and/or PCR

Answer 7

Laboratory Criteria for Diagnosis ■ Isolation of Bordetella pertussis from a clinical specimen (Culture) ■ Positive polymerase chain reaction (PCR) assay for B. pertussis DNA

Answer 8

Pertussis Complications ■ Syncope (temporary loss of consciousness/faint) ■ Sleep disturbance ■ Incontinence ■ Rib fractures ■ Complications among infants – Pneumonia (22%) – Seizures (2%) – Encephalopathy (<0.5%) ■ Death – Infants, particularly those who have not received a primary vaccination series, are at risk for complications and mortality.

Answer 9

– Pneumonia (22%) – Seizures (2%) – Encephalopathy (<0.5%)

Answer 10

■ Complications among infants – Pneumonia (22%) – Seizures (2%) – Encephalopathy (<0.5%)

Answer 11

Treatment • Aim is to eradicate nasopharyngeal carriage • Treatment duration usually 14 days with erythromycin sulfate (EES), newer Macrolides 5-7 days

Answer 12

Treatment • Macrolides-erythromycin, azithromycin, and clarithromycin • Azithromycin eradicates naso-pharyngeal carriage the fastest • Hypertrophic pyloric stenosis has been reported with oral EES in infants younger than 6 weeks • Trimethoprim-sulfamethoxazole is an alternative to erythromycin-resistant strain, or for intolerance to macrolides F • Penicillins, first and second generation cephalosporins are not effective

Answer 13

Immunisation • Two types of pertussis vaccines are available: – Whole-cell (wP) vaccines based on killed B. pertussis organisms – Acellular (aP) vaccines based on one or more highly purified individual pertussis antigens

Answer 14

Immunisation • Two types of pertussis vaccines are available: – Whole-cell (wP) vaccines based on killed B. pertussis organisms – Acellular (aP) vaccines based on one or more highly purified individual pertussis antigens • The wP vaccines were introduced in mid-20th century and included in the Expanded Programme on Immunization since 1974 • Many high-income countries have replaced wP with aP vaccines as a means of decreasing the reactogenicity of the vaccine • Pertussis vaccines are produced as combinations with other antigens;; F- no stand-alone pertussis vaccines are currently available

Answer 15

WHO recommendations • WHO recommends a 3-dose primary series, with the first dose administered at 6 weeks of age;; subsequent doses should be given 4–8 weeks apart • The series should be completed by 6 months of age;; for those who have not completed the schedule, vaccine may be given later than 6 months of age, at the earliest opportunity • For children whose vaccination series has been interrupted, the series should be resumed without repeating previous doses • National programmes using alternate primary vaccination schedules with adequate surveillance should continue using these schedules and continue to monitor disease trends • A booster dose is recommended for children aged 1–6 years, preferably during the second year of life

Answer 16

Legionella pneumophila • Small, gram-negative bacillus • Beta-lactamase producer • Enters and replicates inside macrophages • Causative agent of “Legionnaire’s disease” • Fulminant pneumonia syndrome • Historically associated with contaminated water in air-conditioning systems • Urinary antigen test for diagnosis

Answer 17

Key facts- WHO • The bacterium L. pneumophila was first identified in 1977, as the cause of an outbreak of severe pneumonia in a convention centre in the USA in 1976. • The most common form of transmission of Legionella is inhalation of contaminated aerosols produced in conjunction with water sprays, jets or mists • Infection can also occur by aspiration of contaminated water or ice, particularly in susceptible hospital patients.

Answer 18

Key facts - WHO • Legionnaires’ disease has an incubation period of 2 to 10 days (but up to 16 days has been recorded in some outbreaks). • Death occurs through progressive pneumonia with respiratory failure and/or shock and multi-organ failure. • Untreated Legionnaires’ disease usually worsens during the first week. • Of the reported cases 75–80% are over 50 years and 60–70% are male.

Answer 19

• • • • • • Legionellosis varies in severity from a mild febrile illness to a serious and sometimes fatal form of pneumonia and is caused by exposure to Legionella species found in water, and soil It is often categorized as being community, travel or hospital acquired based on the type of exposure Waterborne Legionella pneumophila is the most common cause of cases including outbreaks Legionella pneumophila and related species are commonly found in lakes, rivers, creeks, hot springs and other bodies of water Other species including L. longbeachae can be found in soil Legionella can survive and grow as parasites within free-living protozoa and within biofilms which develop in water systems

Answer 20

Risk factors For community-acquired and travel-associated legionellosis include: smoking, heavy drinking pulmonary-related illness immuno-suppression chronic respiratory or renal illnesses. For hospital-acquired pneumonia are: recent surgery intubation mechanical ventilation aspiration presence of nasogastric tubes use of respiratory therapy equipment The most susceptible hosts are immuno-compromised patients, including organ transplant recipients and cancer patients and those receiving corticosteroid treatment. Delay in diagnosis and administration of appropriate antibiotic treatment, increasing age and presence of co-existing diseases are predictors of death from Legionnaires’ disease

Answer 21

Symptons • The non-pneumonic form (Pontiac disease) is an acute, self-limiting influenza-like illness usually lasting 2–5 days. The incubation period is from a few and up to 48 hours • fever, chills, headache, malaise and muscle pain (myalgia) • Legionnaires’ disease, the pneumonic form, has an incubation period of 2 to 10 days symptoms are fever, loss of appetite, headache, malaise and lethargy • Some patients may also have mild cough, muscle pain, diarrhoea and confusion. Blood-streaked phlegm or hemoptysis occurs in about one-third of the patients • The severity of disease ranges from a mild cough to a rapidly fatal pneumonia. Death occurs through progressive pneumonia with respiratory failure and/or shock and multi-organ failure

Answer 22

Laboratory diagnosis • culture of lower respiratory secretions (e.g., sputum, bronchoalveolar lavage) on selective media and the Legionellaurinary antigen test • Buffered Charcoal Yeast Extract [BCYE] agar) is confirmatory and an important method for diagnosis • Isolation of Legionella can come from lower respiratory secretions, lung tissue, pleural fluid, or a normally sterile site • Culturing specimens can detect Legionella species and serogroups that the urinary antigen test does not. • The urinary antigen test can detect Legionella infections in some cases for days to weeks after treatment

Answer 23

Test 1.) Culture Sensitivity: 20-80 Specificity: 100 2.) Urinary antigen for L. pneumophila serogroup' (Lp1) Sensitivity: 70-100 Specificity: 95-100 3.) Polymerase Chain Reaction (PCR) Sensitivity: 95-99 Specificity: >99 4.) Direct Fluorescent Antibody (DA) Stain Sensitivity: 25-75 Specificity: >95 5.) Paired serology Sensitivity: 80-90 Specificity: >99

Answer 24

Prevention • Implementing water safety plans • Good maintenance of devices, including regular cleaning and disinfection and applying other physical (temperature) or chemical measures (biocide) to minimize growth

Brucellosis, meloidosis, whooping cough, legionnairres Flashcards

(48 cards)