PregVax Project
Project Summary
Approximately 25 million pregnant women exposed yearly to malaria live in areas where Plasmodium vivax is endemic (Menéndez, et al., 2007). While the effects of falciparum
malaria in pregnancy have been well characterised and are responsible
for considerable maternal and infant morbidity and mortality (Desai, et
al., 2007), surprisingly little is known about the impact of P. vivax infection during gestation.
Malaria in pregnancy has been recently prioritised by the 7th Framework Program of the European Commission. To fill the knowledge gaps of vivax malaria in pregnancy, the PregVax study will carry out a cohort observational study in pregnant women in five P. vivax endemic countries, Brazil, Colombia, Guatemala, India, and Papua New Guinea, broadly representing most of the world's P. vivax infections (Mendis, et al., 2001; Müeller, et al., 2004; Valecha, et al., 2006; Martinez-Espinosa, et al., 2004).
Two thousand pregnant women will be enrolled in each site at the time of routine antenatal care visits and followed-up at the health facility until delivery or end of pregnancy. Clinical-epidemiological studies and immunological analysis will be performed in order to:
- assess Plasmodium vivax malaria parasitemia,
- determine the prevalence of infection at each site,
- assess the impact of Plasmodium vivax malaria on birth weight, and
- unveil whether there are pregnancy-specific immune responses.
Problem
Recently, there have been reports from Latin America (Rodriguez-Morales, et al., 2006), Thailand (Nosten, et al., 1999) and India (Kochar, et al., 2005) suggesting that Plasmodium vivax infection may be associated with poor pregnancy outcomes, mainly maternal anaemia, low birth weight and miscarriage. These studies, mostly based on very small numbers, provide inconsistent information about P. vivax in pregnancy. Additionally, they provide only partial information on the epidemiological and clinical aspects of the infection in pregnancy.
Main Objectives
The main objective of the PregVax study is to describe the epidemiological and clinical features of Plasmodium vivax malaria in pregnancy. The PregVax study will also determine if there are pregnancy-specific immune responses and characterize, genotypically and phenotypically, parasites of the placenta.
Specific Objectives
- To describe the epidemiology of Plasmodium vivax infection in pregnancy in different endemic areas
- To estimate the prevalence of infection at the time of first attendance to routine antenatal clinics and at time of delivery
- To estimate the incidence of infection
- To assess the clinical impact of Plasmodium vivax infection during pregnancy on maternal outcomes (e.g. anaemia, severe complications) and foetal outcomes (e.g. low birth weight, prematurity, and congenital infection)
Expected Results
Compiling information in a methodologically standardized way will allow a precise assessment of the prevalence of Plasmodium vivax infection during gestation at each study site and provide a description of Plasmodium vivax infection impact during pregnancy. Phenotypic and genotypic analyses of parasites from the placenta should reveal, respectively, their adhesive properties and whether the accumulation of Plasmodium vivax-infected erythrocytes in the placenta selects unique parasite populations.
Potential Applications
A more precise description of the impact of vivax malaria during gestation will help improve its clinical management. Accurate data on the prevalence and incidence of the infection is essential to guide control policies. Furthermore, elucidating the mechanisms involved in the pathology of P. vivax in pregnancy will help to develop specific control tools such as more effective drugs and vaccines.
Finally, understanding the mechanism involved in Plasmodium vivax malaria may also help to elucidate important gaps in the knowledge of Plasmodium facilparum infection in pregnancy.
Progress of the Study
The PregVax study is currently in its final straight. Recruitment and follow up of the cohort finished in December 2011. Figures are shown in the table below.
|
Brazil |
Colombia |
Guatemala |
India |
PNG |
Total |
||
|
ANC Scheduled Visits |
1st ANC Visit (Enrolment) |
1696 |
2039 |
2009 |
2050 |
1679 |
9473 |
|
2nd & 3rd ANC Visit (Follow up visits) |
1537 |
1754 |
1324 |
604 |
2358 |
7577 |
|
|
Non-Scheduled Visits |
Through Passive Case Detection |
118 |
202 |
63 |
53 |
838 |
1274 |
|
Deliveries |
905 |
783 |
1025 |
1332 |
935 |
4980 |
|
|
Questionnaires in the database |
~17000 |
~18000 |
~20000 |
~22000 |
~21000 |
> 98000 |
Currently, few more samples are being analysed to get more accurate data on molecular diagnosis. As well, few last experiments on immunology are on-going. Preliminary results are already available and have been presented at several international congresses. Once all data has been gathered together will be published. Findings about Placental infection with P.vivax have been published (doi: 10.1093/infdis/jis614). During the study, a P.vivax congenital case was found. Insights have been published as a case report (doi: 10.1186/1475-2875-11-411).
See a brief overview on PregVax
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Watch this video “Facing an underestimated malaria” for a better understanding on malaria impact on pregnant women and newborns