Lecture 15

Question 1

Mechanisms of CNS infection

Answer 1

• bloodborne spread
• head trauma
• neurosurgical procedures
• medical devices
• congenital malformations
• mastoid or ear infections

Question 2

Meningitis pathogens

Answer 2

• bacteria: s pneumoniae, n meningitidis, group B strep, e coli
• viruses: enterovirus, arbovirus, herpes simplex

Question 3

Encephalitis pathogens

Answer 3

• viruses: herpes simplex, arboviruses

Question 4

Brain abscess

Answer 4

• bacteria: s pneumoniae, group A strep, anaerobes, h influenzae

Question 5

bacterial meningitis surveillance in the netherlands: 1988-2019

Answer 5

• nationwide surveillance in the netherlands
• impact of conjugate vaccines on incidence

Question 6

Netherlands meningitis surveillance findings

Answer 6

• H influenzae and N meningitidis most common in preschool children
• P meningitis in older adults
• Group B strep and E coli in infants
• incidence highest in infants and preschoolers in the pre-vaccination period

Question 7

Netherlands meningitis surveillance trends

Answer 7

• Introduction of Hib and men C vaccine lead to decrease in H influenzae, N meningitidis (1996, 2009)
• S pneunomiae not affected by vaccine

Question 8

Neisseria meningitidis in the US

Answer 8

• 2005: MCV4 vaccine reduced cases of serogroups A, C, Y, and W-135
• Serogroup B now the leading cause of invasive disease in rich countries
• MenB vaccine recommended for certain risk groups/during outbreaks

Question 9

Haemophilus influenzae in the US

Answer 9

• Hib related meningitis declined 95% between 1987 to 1993
• introduction of vaccine

Question 10

Streptococcus pneumoniae in the US

Answer 10

• 2000: PCV7 reduced disease by 95%
• non-vaccine serotypes replaced after vaccine, reduction plateued

Question 11

global case fatality rates - bacterial meningitis

Answer 11

• 371 studies in 108 countries from 1935-2019
• before 1961, pathogen identified in only 79% of cases
• CFR decreased from 32% in 1961 to 15% in 2010
• higher CFR in LMICs across age groups

Question 12

Aseptic meningitis

Answer 12

• self limited CNS syndrome with acute onset of fever, meningeal irritation, sterile cerebrospinal fluid
• highest incidence in children
• most common cause is enteroviruses

Question 13

Aseptic meningitis seasonality

Answer 13

• enteroviruses transmitted from April/May to August/September - summer
• many different serotypes, changes by year

Question 14

Non viral causes of aseptic meningitis

Answer 14

• less than half of cases
• Bacteria: borrelia, mycoplasma pneumoniae
• parasite: naegleria fowleri
• fungal: cryptococcus neoformans in HIV
• non-infectious: autoimmune conditions (lupus, vasculitis)

Question 15

Acute encephalitis

Answer 15

• cause is unknown in half of cases
• all age groups, no seasonality, geographic patternA

Question 16

Acute encephalitis causes

Answer 16

• herpes simplex: 50-75%, adults
• arboviruses: fastest growing, ecology of arboviral transmission
• enteroviruses

Question 17

Acute encephalitis arboviruses

Answer 17

• birds/small mammals act as reservoirs
• transmission from mosquito/tick
• drivers are land use changes, international travel and commerce, urbanization, climate change
• increase in incidence and distribution of viruses/vectors

Question 18

West Nile

Answer 18

• culex
• encephalitis

Question 19

Yellow Fever

Answer 19

• aedes aegypti
• febrile illness with jaundice

Question 20

Dengue

Answer 20

• a aegypti, a albopictus
• dengue hemorrhagic fever with shock

Question 21

Zika

Answer 21

• a aegypti
• congenital infection: severe microcephaly

Question 22

Arboviruses in the US

Answer 22

• West Nile, chikungunya, dengue, zika