neurosyphilis patients with primary sporozoite-induced P. vivax infections.
They showed that haemoglobin fell rapidly during the first 4-5 weeks of
untreated infection and subsequently climbed gradually as immunity was
acquired. Premorbid haemoglobin concentrations had still not been reached
by week 11 of infection ( Collins et al., 2003 ).
Anaemia associated with P. vivax infection is amongst the commonest
manifestations of severe vivax disease and is more strongly skewed towards
young children than the anaemia caused by P. falciparum infection ( Tjitra
et al., 2008 ; Poespoprodjo et al., 2009 ; Michon et al., 2007 ; Lin et al., 2010 ;
Ladeia-Andrade et al., 2009 ; Douglas et al., 2012). Even in adults, severe
anaemia can be a common manifestation of severe disease as highlighted
in two series from Papua, Indonesia. In Timika, southern Papua, 10% of
all adults hospitalised with P. vivax infections between 2005 and 2007 had
severe anaemia (haemoglobin <5 g/dl) ( Tjitra et al., 2008 ). In Jayapura,
northern Papua, 6% of adults hospitalised with P. vivax malaria had a hae-
moglobin concentration of <6 g/dl ( Barcus et al., 2007 ). In other series
from India and Brazil, severe anaemia accounted for almost one-third of all
cases of severe adult vivax malaria ( Kochar et al., 2009 ; Andrade et al., 2010 ).
Conversely, in a hypoendemic region of north western Thailand, none of
the 1978 adults and children of age >5 year diagnosed with acute vivax
malaria over a 3-year period required hospitalisation for severe anaemia or
blood transfusion, though haemoglobin was not routinely quantitated in the
community ( Luxemburger et al., 1997 ).
Post-pubescent females are at greater risk than young males of being
admitted to hospital with P. vivax malaria in Southern Papua ( Tjitra et al.,
2008 ) and in one large analysis from the same region, had more severe anae-
mia than males (unpublished data). This is likely to relate at least partially
to lower premorbid haemoglobin concentrations. In addition, pregnant
women with vivax malaria have at least a twofold higher risk of moderate
anaemia than pregnant women without vivax infection (Section 8.3 ), a risk
that has been demonstrated in several different geographical locations ( Nos-
ten et al., 1999 ; Poespoprodjo et al., 2008 ; Rodriguez-Morales et al., 2006 ).
As mentioned above, the anaemia of vivax malaria may be modulated
by myriad co-morbidities including gastrointestinal helminth infections
and malnutrition (Section 8.2.1 ), haemoglobin and red cell abnormalities,
chronic inflammatory or myelosuppressive diseases and acute bacterial
infections (Douglas et al., 2012). Population-based studies of the hae-
matological morbidity associated with vivax malaria have yet to address
adequately all of these co-factors.