Background The
yellow fever vaccine is regarded as one of the safest attenuated
virus vaccines , with few side-effects or adverse events. We
report the occurrence of two fatal cases of haemorrhagic
fever associated with
yellow fever 17DD substrain
vaccine in
Brazil .
Methods We obtained epidemiological, serological, virological, pathological, immunocytochemical, and molecular
biological data on the two cases to determine the cause of the illnesses. Findings The first case, in a 5-year-old
white girl , was characterised by sudden onset of
fever accompanied by
headache , malaise, and
vomiting 3 days after receiving
yellow fever and
measles -
mumps -
rubella vaccines . Afterwards she decompensated with
icterus and haemorrhagic signs and died after a 5-day illness. The second
patient a 22-year-old black
woman developed a
sore throat and
fever accompanied by
headache ,
myalgia ,
nausea , and
vomiting 4 days after
yellow fever vaccination . She then developed
icterus ,
renal failure , and haemorrhagic
diathesis , and died after 6 days of illness.
Yellow fever virus was recovered in suckling
mice and C6/36
cells from
blood in both cases, as well as from fragments of
liver ,
spleen ,
skin , and
heart from the first case and from these and other
viscera fragments in case 2.
RNA of
yellow fever virus was identical to that previously described for 17D genomic sequences.
IgM ELISA tests for
yellow fever virus were negative in case 1 and positive in case 2;
similar tests for
dengue , hantaviruses,
arenaviruses ,
Leptospira , and
hepatitis viruses AD were negative.
Tissue injuries from both
patients were typical of wild-type
yellow fever . Interpretation These serious and hitherto unknown
complications of
yellow fever vaccination are extremely rare, but the
safety of
yellow fever 17DD
vaccine needs to be reviewed. Host factors, probably idiosyncratic reactions, might have had a substantial contributed to the unexpected outcome.