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stroke and congestive heart failure ( Lacerda et al., 2012 ). Similarly, a USA
series reported two malaria deaths due to P. vivax , both of which were in
patients with pre-existing cardiac disease ( Stoppacher and Adams, 2003 ).
Among the 24 Brazilian children with severe P. vivax infection requiring
intensive care admission, 25% had concomitant acute gastroenteritis, and
in total, 58% had a concurrent acute or chronic co-morbidity potentially
contributing to severe illness ( Lanca et al., 2012 ). All the co-morbidities
above are common in malaria-endemic regions, and it is likely that their
importance in contributing to severe and fatal outcomes in P. vivax infec-
tions is underestimated (see Price et al., 2009 ; Anstey et al., 2009 for
8.1. Severe Malaria in Adults
A broad range of severe vivax syndromes has been described in adult series
similar to that described in adult falciparum malaria. This spectrum could
reflect the application of criteria for severity, which were developed explic-
itly for defining patients with P. falciparum infection at risk of dying ( World
Health Organization, 2010 ). However, two recent series from Brazil suggest
that the criteria in current WHO guidelines for severe falciparum malaria
are sensitive in identifying children requiring intensive care admission
( Lanca et al., 2012 ) and identifying patients at risk of death ( Lacerda et al.,
2012 ). The latter report suggested adding splenic rupture as a severe malaria
criterion, but it was not clear from this study whether antemortem appli-
cation of the current severe malaria criterion of shock would have already
identified patients subsequently dying of splenic rupture.
8.1.1. Severe anaemia
There is a continuum of anaemia associated with P. vivax malaria ranging
from minor to profound. Severe anaemia secondary to P. vivax infection is
typically defined as a haemoglobin concentration of <5 g/dl ( World Health
Organization, 2010 ) though forthcoming WHO guidelines will define a
cut off of 7 g/dl in adults. The degree of anaemia in an individual is influ-
enced by a wide range of factors including (but not limited to) premorbid
haemoglobin concentration, level of immunity, duration of infection before
treatment, the number of prior episodes of malaria, as well as the pres-
ence of comorbid conditions. Collins et al. (2003) analysed data from adult
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