Is Plasmodium vivax a severe malaria?: a systematic review and meta-analysis

Background: Plasmodium vivax is one of the major species of malaria infecting humans. Although emphasis on P. falciparum is appropriate, the burden of vivax malaria should be given due attention. This study aimed to synthesize the evidence on severe malaria in P. vivax infection compared with that in P. falciparum infection. Methods/Principal Findings: We searched relevant studies in electronic databases. The main outcomes required for inclusion in the review were mortality, severe malaria (SM) and severe anaemia (SA). The methodological quality of the included studies was assessed using the Newcastle-Ottawa Scale. Overall, 26 studies were included. The main meta-analysis was restricted to the high quality studies. Eight studies (n = 27490) compared the incidence of SM between P. vivax infection and P. falciparum mono-infection; a comparable incidence was found in infants (OR: 0.45, 95% CI:0.04-5.68, I2:98%), under 5 year age group (OR: 2.06, 95% CI: 0.83-5.1, I2:83%), the 5-15 year-age group (OR: 0.6, 95% CI: 0.31-1.16, I2:81%) and adults (OR: 0.83, 95% CI: 0.67-1.03, I2:25%). Six studies reported the incidences of SA in P. vivax infection and P. falciparum mono-infection; a comparable incidence of SA was found among infants (OR: 3.47, 95%:0.64-18.94, I2: 92%), the 5-15 year-age group (OR:0.71, 95% CI: 0.06-8.57, I2:82%). This was significantly lower in adults (OR:0.75, 95% CI: 0.62-0.92, I2:0%). Five studies (n = 71079) compared the mortality rate between vivax malaria and falciparum malaria. A lower rate of mortality was found in infants with vivax malaria (OR:0.61, 95% CI:0.5-0.76, I2:0%), while this was comparable in the 5-15 year- age group (OR: 0.43, 95% CI:0.06-2.91, I2:84%) and the children of unspecified-age group (OR: 0.77, 95% CI:0.59-1.01, I2:0%). Conclusion: Overall, the present analysis identified that the incidence of SM in patients infected with P. vivax was considerable, indicating that P. vivax is a major cause of SM. Awareness of the clinical manifestations of vivax malaria should prompt early detection. Subsequent treatment and monitoring of complications can be life-saving

Malaria and soil-transmitted intestinal helminth co-infection and its effect on anemia: a meta-analysis

This study aimed to synthesize available evidence on the extent of malaria and soil-transmitted intestinal helminth (STH) co-infections in people living in endemic countries and to explore the effect of interactions between malaria and STHs on anemia. We searched relevant studies in electronic databases up to March 2013. Studies comparing malaria and STH co-infected patients with those not co-infected were included and the effect estimates were pooled using a random-effects model. We identified 30 studies for meta-analyses of which 17 were cross-sectional design. The majority of included studies (80%) were carried out in African countries. Among pregnant women, those infected with hookworm were found to have higher association with malaria infection compared with those without (summary OR: 1.36; 95% CI: 1.17-1.59; I2: 0%). Among non-pregnant adults, the summary OR of the association between anemia and the combined malaria and STH was 2.91 (1.38-6.14). The summary OR of the association between anemia and malaria alone was 1.53 (0.97-2.42), while the association between anemia and STH alone was 0.28 (0.04-1.95). There is no good evidence to support a different effect of malaria and STH on anemia. A subgroup analysis showed a higher risk of malaria infection in the primigravidae (summary OR: 1.61; 95% CI: 1.3-1.99; I2: 0%). In conclusion, the malaria-STH co-infection was variable with complex outcomes on anemi

Forest plot showing a comparison of mortality between <i>P. vivax</i> and <i>P. falciparum</i> mono-infections.

<p>Forest plot showing a comparison of mortality between <i>P. vivax</i> and <i>P. falciparum</i> mono-infections.</p

Forest plot showing a comparison of severe malaria between <i>P. vivax</i> and <i>P. falciparum</i> mono-infections.

<p>Forest plot showing a comparison of severe malaria between <i>P. vivax</i> and <i>P. falciparum</i> mono-infections.</p

Forest plot showing a comparison of severe anaemia between <i>P. vivax</i> and <i>P. falciparum</i> infections.

<p>Forest plot showing a comparison of severe anaemia between <i>P. vivax</i> and <i>P. falciparum</i> infections.</p

Funnel plot showing publication bias among studies on severe malaria.

<p>Funnel plot showing publication bias among studies on severe malaria.</p

Stratified analysis of severe malaria according to the chloroquine resistant status of the study sites.

<p>Stratified analysis of severe malaria according to the chloroquine resistant status of the study sites.</p

Flow diagram indicating the study selection.

<p>Flow diagram indicating the study selection.</p

Malaria and soil-transmitted intestinal helminth co-infection and its effect on anemia : a meta-analysis

This study aimed to synthesize available evidence on the extent of malaria and soil-transmitted intestinal helminth (STH) co-infections in people living in endemic countries and to explore the effect of interactions between malaria and STHs on anemia. We searched relevant studies in electronic databases up to March 2013. Studies comparing malaria and STH co-infected patients with those not co-infected were included and the effect estimates were pooled using a random-effects model. We identified 30 studies for meta-analyses of which 17 were cross-sectional design. The majority of included studies (80%) were carried out in African countries. Among pregnant women, those infected with hookworm were found to have higher association with malaria infection compared with those without (summary OR: 1.36; 95% CI: 1.17-1.59; I(2): 0%). Among non-pregnant adults, the summary OR of the association between anemia and the combined malaria and STH was 2.91 (1.38-6.14). The summary OR of the association between anemia and malaria alone was 1.53 (0.97-2.42), while the association between anemia and STH alone was 0.28 (0.04-1.95). There is no good evidence to support a different effect of malaria and STH on anemia. A subgroup analysis showed a higher risk of malaria infection in the primigravidae (summary OR: 1.61; 95% CI: 1.3-1.99; I(2): 0%). In conclusion, the malaria-STH co-infection was variable with complex outcomes on anemia