Prevalence of parasitic infections
Our search of published literature relevant to the aetiology and epidemiology of maternal parasitic infections in the developing world provided detailed epidemiological information on 6 maternal infections. These 6 parasitical maternal infections were most extensively studied, suggesting that these infections have a high burden on pregnancy outcomes in the developing world. These infections also have potential adverse effects on neonates.
Malaria in its own right is a major contributing factor towards maternal deaths worldwide. It causes severe anaemia and can affect newborn‘s birth-weight and long-term survival (119). For this reason, it is recommended that research conducted in South and Central America, especially Brazil where the prevalence of P. vivax was so high (78.69%) to be expanded (28). Further research should also be concentrated on regions classified as high risk but with a current lack of data like Democratic Republic of Congo, Angola and Zambia, from where no evidence of research was found. Finally, prevention strategies should be encouraged in the maternal populations from the countries with evidence of very high malaria prevalence, namely Gabon, India, Cameroon, Yemen, Nigeria and Ghana (26,29,39,46,47,49,51).
Hookworm infections were found to be well studied, which is very promising as these parasites cause anaemia during pregnancy and have been noted to increase the maternal and child mortality rates (120). However more studies looking at Schistosoma would definitely be recommended as there were only 4 studies in pregnant women, despite WHO’s statement that Schistosoma is “second only to malaria in public health importance” and pregnant women are one of the important at risk groups (121). Specific countries of note for further investigation and preventative measures would be Nepal for hookworm (78.8%) and A. lumbricoides (56.2%) (19); Tanzania for hookworms (56.3%) and Schistosoma mansoni (63.5%) (24); Kenya for hookworms (39.5%) and A. lumbricoides (52.3%); the Gabon for A. lumbricoides (45.5%) and Trichuris trichuria (31%); and finally for S. mansoni (50%) (10,11,18).
Chagas disease is important because of its potential to cause mortality in all age-groups. It can be transmitted vertically so that the knowledge of maternal prevalence is important (122). Although this review has shown studies in South America, the disease is no longer confined to just South America, as with Latino American emigration there has been a movement of the disease across the world. Therefore global research in areas of high Latino American immigration would be recommended to assess the extent this emigration has had (123). More funding in Bolivia would be recommended to assess the nature of the 26.3% prevalence of maternal infection and its effects on maternal and neonatal health (9).
There is a need for more studies on Leishmania would also be recommended from the results. Although not much evidence can be taken from the single study from Brazil (124), pregnant woman tended to have more severe Leishmania than the non-pregnant infected subjects and there was a possible link with increased problems with pregnancy (124).
Strengths and limitations
To our knowledge, this is the first review that summarises the epidemiology of maternal parasitic infections in the developing world. The search strategy devised was sensitive and specific, which allowed for a comprehensive review of available literature on this topic. The information generated in this review can be used to guide public health policy and the allocation of resources within local governments and by the international community towards improving maternal health. Although the search did not exclude non-English papers, we did not search some of the databases where we would have expected a higher concentration of foreign language papers (e.g. LILACS). Although the databases used were very extensive, especially in the case of EMBASE and Medline there is a high chance that important papers could have been recovered from smaller, more specialist databases.
This study could be further improved by analysing non-English studies conducted in francophone parts of Africa (in French), South America (in Spanish) and in China (in Chinese), which could be accessed from appropriate databases. Reviewing non-English articles may assist in defining the epidemiology of pathogens for which we managed to identify few (<5) studies, as well as providing more robust data on the pathogens presented in this review. In addition, searching grey (unpublished) literature or contacting health officials and researchers in the field may also yield more country specific data on the subject, thus enabling more targeted and context-specific public health measures.
Recommendations and future work
This systematic review highlights the quantity of maternal parasitic infection research and, to a lesser extent, quality of research that has been achieved over the last 30 years. This paper would therefore be useful to decision makers, especially in light of the US$ 40 billion (€ 30 billion) pledged at the last UN’s MDG summit, to help them assess where best to implement resources for research. It could also be a useful tool to measure how good the data are for each individual parasite and in assessing what areas of the world have been neglected in terms of research. With a full picture where different maternal infections occur, it could be used as a tool to target research and could ultimately lead to big leap forward maternal infections knowledge, therefore helping in the fight towards cutting down maternal infections.
No mother should die during childbirth and every step should be taken to stop this happening. This review is a first step, in a long chain of events, trying to prevent maternal mortality. If research and knowledge is channelled into the right areas and decision makers have accurate knowledge regarding maternal infections then resources can be allocated to those areas that need it most.
Researchers have a responsibility to reflect on which part of the world current knowledge is stemming from and should look retrospectively to see how much research has been done in the past. By doing this, the public health community can positively expand research into areas of the world and into diseases where that information is lacking. And with this information, informed and important decision can be made about the factors that affect maternal mortality most and maybe, just maybe, Millennium Development Goal 5 can be achieved.