Summary Chronic infections during pregnancy are highly prevalent in some parts of the world. Infections with helminths, Trypanosoma cruzi, Plasmodium spp, and HIV might affect the development of fetal immunity and susceptibility to postnatal infections independently of in-utero transmission of the pathogens. Fetal adaptive immune responses are common in neonates who have been exposed to maternal infection during pregnancy but not infected themselves. Such responses could affect the development of immunity to the homologous pathogens and their control during the first few years of life. Fetal innate and regulatory responses might also affect immunity to unrelated pathogens and responses to vaccines. Strategies to improve child health should integrate the possible clinical implications of in-utero exposure to chronic maternal infections.

https://www.thelancet.com/pdfs/journals/laninf/PIIS1473-3099(11)70341-3.pdf

Uninfected but not unaffected: chronic maternal infections during pregnancy, fetal immunity, and susceptibility to postnatal infections

On a global basis, both potent vaccine efficacy and high vaccine coverage are necessary to control and eliminate vaccine-preventable diseases. Emerging evidence from animal and human studies suggest that neglected tropical diseases (NTDs) significantly impair response to standard childhood immunizations. A review of efficacy and effectiveness studies of vaccination among individuals with chronic parasitic infections was conducted, using PUBMED database searches and analysis of data from the authors' published and unpublished studies. Both animal models and human studies suggest that chronic trematode, nematode, and protozoan infections can result in decreased vaccine efficacy. Among pregnant women, who in developing countries are often infected with multiple parasites, soluble parasite antigens have been shown to cross the placenta and prime or tolerize fetal immune responses. As a result, antenatal infections can have a significant impact on later vaccine responses. Acquired childhood parasitic infections, most commonly malaria, can also affect subsequent immune response to vaccination. Additional data suggest that antiparasite therapy can improve the effectiveness of several human vaccines. Emerging evidence demonstrates that both antenatal and childhood parasitic infections alter levels of protective immune response to routine vaccinations. Successful antiparasite treatment may prevent immunomodulation caused by parasitic antigens during pregnancy and early childhood and may improve vaccine efficacy. Future research should highlight the varied effects that different parasites (alone and in combination) can have on human vaccine-related immunity. To optimize vaccine effectiveness in developing countries, better control of chronic NTDs may prove imperative.

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Do antenatal parasite infections devalue childhood vaccination

Mansonella perstans filariasis in Africa.

Iconographies supplémentaires de l'article : Uninfected but not unaffected: chronic maternal infections during pregnancy, fetal immunity, and susceptibility to postnatal infections

Polyparasitism and its impact on the immune system.

Introduction
Helminth infections and malaria are widespread in the tropics. Recent studies suggest helminth infections may increase susceptibility to malaria. If confirmed, this could be particularly important during pregnancy-induced immunosuppression.

Stephen D. Hillier

Papers

Plasmodium falciparum and Helminth Coinfection in a Semiurban Population of Pregnant Women in Uganda