Biology Reference
In-Depth Information
6. RISK OF SEVERE DISEASE AND DEATH
Plasmodium vivax
infection in healthy travellers from non-endemic
countries and healthy residents of low-endemicity temperate regions of
Asia rarely causes severe disease (see
Price et al., 2009
for review). These
populations are predominantly adults without co-morbidities, with ready
access to early diagnosis and effective treatment, and usually associated with
infrequent recurrence due to low risk of reinfection and better anti-relapse
therapy (
Price et al., 2009
). Deaths in travellers have been reported, but
are generally associated with co-morbidities which may have contributed
substantially to pathology (
Stoppacher and Adams, 2003
). In other endemic
areas, the risk of severe disease rises with increasing transmission intensity
of early and frequent relapse. Such regions often contain poorly resourced
communities with less access to early diagnosis and treatment and greater
prevalence of co-morbidities such as malnutrition and co-infections (
Price
et al., 2009
).
Few studies have identified population-based risk of severe disease from
P. vivax
in endemic settings. In one series from Indonesian Papua, the risk
of severe disease and death associated with
P. vivax
was estimated at one in
270 and one in 3959 clinical infections, respectively (
Tjitra et al., 2008
).
This compared to estimates for
P. falciparum
of one in 185 and one in 1742,
respectively (
Tjitra et al., 2008
). In Indonesian Papua, the hospital mortal-
ity rates in those hospitalised with
P. vivax
confirmed by microscopy were
reported as 0.8-1.6%, similar to that of
P. falciparum
infection (1.6-2.2%)
(
Price et al., 2009
;
Barcus et al., 2007
;
Tjitra et al., 2008
). Similarly, case-
fatality rates in Indian children hospitalised with PCR-confirmed
P. vivax
monoinfection (3.9%) were comparable to that seen in PCR-confirmed
P.
falciparum
infection (3.2%) (
Kochar et al., 2010
). A higher mortality (8.3%)
was observed in a Brazilian study of 24 children admitted to an intensive
care unit with severe disease associated with microscopy-diagnosed
P. vivax
(
Lanca et al., 2012
). In other settings, case-fatality rates are lower, and in
children hospitalised in Thailand, were lower with
P. vivax
infection (0.22%)
than with
P. falciparum
(1.2%) (
Wattanagoon et al., 1994
). The risk of death
varies significantly between syndromes. For infants hospitalised with severe
anaemia without respiratory distress, mortality was 0.4%, but increased to
10.2% in whom respiratory distress was also present (
Tjitra et al., 2008
).
Over the past few years, increasing reports of severe vivax has raised
awareness of the potential adverse consequences of
P. vivax
, however, almost
all have been limited by incomplete systematic investigation of concurrent
