Do Antenatal Parasite Infections Devalue Childhood Vaccination?

Abstract

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parasitic infections was conducted, using PUBMED database searches and analysis of data from the authors' published and unpublished studies.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.

Antagonism between two intestinal parasites in humans: the importance of co-infection for infection risk and recovery dynamics

“…multiple species of helminth [2]), relatively little is known about the interactions between many common parasites and pathogens. Investigation of co-infection is important, since co-infection may alter both treatment and susceptibility to infection [3,4].…”

Malaria Modifies Neonatal and Early-Life Toll-Like Receptor Cytokine Responses

“…hronic infections during pregnancy, including those of parasitic origin, are a frequent occurrence in low-income areas of the world in general and in sub-Saharan African countries in particular, and they affect fetal immunity such that infants' responses to vaccination are diminished and their susceptibility to infection is increased (1,2). Maternal infection with Trypanosoma cruzi, for example, without vertical transmission, stimulates fetal innate and adaptive immune responses such that exposed but uninfected neonates produce higher concentrations of proinflammatory and anti-inflammatory cytokines than their unexposed counterparts (3,4).…”

Make New Friends and Keep the Old? Parasite Coinfection and Comorbidity in Homo sapiens

“…Multiple STH infections are often associated with increased infection intensity, egg output, and morbidity (Booth et al 1998 ;Brooker et al 2000 ;Ellis et al 2007 ;Pullan and Brooker 2008 ). It is also increasingly documented that helminth infection and helminth-typical immune biasing may diminish immune responses to vaccines, viruses, and bacteria, resulting in increased susceptibility to other infectious diseases (e.g., HIV/AIDS (Bentwich et al 1995 ); BCG, typhoid, measles, and polio vaccines (Labeaud et al 2009 ); tuberculosis (Lienhardt et al 2002 )). In sum, helminths may interact with human immune function and other host factors in a myriad of complex ways that have varying implications for human health.…”