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11.2.5. Multiorgan dysfunction and shock
The extent to which multiorgan dysfunction and shock are attributable to
sepsis-like inflammatory responses to P. vivax , the gram-negative bacterial
co-infection known to occur during P. vivax infection ( Piyaphanee et al.,
2007 ; Sur et al., 2006 ), or both, requires further study. Negative blood cul-
tures reported in some series are limited by widespread pre-hospitalisation
use of antibiotics in the community, and the known insensitivity of pre-
antibiotic blood cultures in bacterial sepsis ( Davis et al., 2011 ), with con-
comitant sepsis not being excluded by negative blood cultures.
Nevertheless, plausible hypotheses have been advanced to explain septic
shock-like presentations in P. vivax infections, particularly in endemic set-
tings with a high prevalence of bacterial co-infections, including Plasmo-
dium -induced priming of host inflammatory responses to bacterial TLR
agonists ( Franklin et al., 2009 ; Leoratti et al., 2012 ) (Section 11.1.6 ).
11.2.6. Pregnancy-associated malaria and low birth weight
P. vivax does not appear to sequester in the placenta although published
reports are limited ( McGready et al., 2004 ). Placental histopathology shows
haemozoin deposition, but inflammatory and pathological changes are
otherwise modest ( McGready et al., 2004 ). Systemic and placental inflam-
matory responses and microvascular dysfunction from vivax malaria may
cause deleterious utero-placental haemodynamic effects and foetal growth
restriction ( McGready et al., 2004 ; Rogerson et al., 2007 ; Umbers et al.,
2011 ; Rijken et al., 2012b ). Maternal anaemia, common in vivax malaria
( Poespoprodjo et al., 2008 ; Rijken et al., 2012a ), is likely to be an additive
cause of low birth weight ( Rogerson et al., 2007 ).
It is clear that P. vivax is responsible for major morbidity and sig-
nificant mortality in vivax-endemic areas. A single infection causing febrile
illness in otherwise healthy individuals rarely progresses to severe disease,
particularly with early treatment and anti-relapse therapy. Nevertheless, it
has been long recognized that P. vivax can cause severe illness and fatal out-
come in the presence of acute and chronic co-morbidities. Such co-mor-
bidities, including malnutrition, anaemia, concurrent bacterial infections
and chronic renal, liver and lung disease, are common in vivax-endemic
regions. While some of these co-morbidities are alternative causes of severe
and fatal disease in co-incidentally parasitized patients, others are likely to
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