Malaria is still a health problem in the world. Five species can infect humans, namely Plasmodium falciparum, Plasmodium vivax, Plasmodium malaria, Plasmodium ovale, and Plasmodium knowlesi.Four species are considered true parasites of humans, while P. knowlesi is still considered a zoonotic malaria. Among these species, P. falciparum and P. vivax are the most prevalent worldwide, in which the most common complications of severe malaria occur in P. falciparum infection. 1 The most frequent clinical manifestation of malaria is fever or recent history of fever. However, because many diseases also have fever as primary clinical manifestation even in the endemic area, accurate laboratory parameter is crucial. False-positive will lead to improper use of antimalarial therapy, and obviously, underdiagnosed cases cause an increase in morbidity, mortality, and antimalaria resistance. 2 The most frequently used method for early detection of malaria infection and remains the gold standard for laboratory confirmation of malaria is microscopic because it is easy to use and cheap. However, there are still many weaknesses in its application. 3

Intestinal protozoan infection is a persisting public health problem affecting the populations of developing countries in the tropical and subtropical regions. The diagnosis of intestinal protozoa remains a challenge especially in developing countries due to a shortage of laboratory facilities, limited health funding, and the remoteness of communities. Despite still being widely used, conventional diagnoses using microscopy and staining methods pose important limitations, particularly due to their low sensitivities and specificities. The selection of diagnostic methods needs to be carefully considered based on the objective of examination, availability of resources, and the expected parasite to be found. In this review, we describe various immunodiagnosis and molecular diagnostic methods for intestinal protozoa infection, including their advantages, disadvantages, and suitability for different settings, with a focus on Entamoeba histolytica, Giardia duodenalis, and Cryptosporidium spp.

The mucosal immune system contributes for the largest component of the tissue immune system due to its massive surface area and constant exposure to the microbiota. The gut microbiota comprises a complex micro‐ecosystem in the intestine and plays a major role in regulating innate and adaptive immunity. Several studies revealed that infectious diseases involve bidirectional interactions in the gut microenvironment, including changes in the gut microbiota composition. During Plasmodium infection, an increase of pro‐inflammatory cells in the lamina propria and a shift in the composition of the gut microbiota contribute to intestinal ecosystem dysbiosis. Although the mechanisms of this dysbiosis is still uncertain, it is thought to be associated with the sequestration of infected red blood cells in the intestinal microvascular system, leading to endothelial villous disruption, and thus activating effector immune cells scattered in the intestinal epithelium and lamina propria. This review provides information on this conjoint interaction which will be beneficial to modulate the host immune response in malaria through manipulation of the gut microbiota composition.

During Plasmodium berghei (P. berghei) infection, infected erythrocytes are sequestered in gut tissues through microvascular circulation, leading to dysbiosis. This study aimed to investigate the effect of Lactobacillus casei (L. casei) and Bifidobacterium longum (B. longum) administration on the parasitemia level, gut microbiota composition, expression of cluster of differentiation 103 (CD103) in intestinal dendritic and T regulatory cells (T reg), plasma interferon gamma (IFN-γ) and tumor necrosis factor (TNF-α) levels in P. berghei infected mice. Methods: P. berghei was inoculated intraperitoneally. Infected mice were randomly divided into 5 groups and treated with either L. casei, B. longum, or the combination of both for 5 days before up to 6 days post-infection (p.i). The control group was treated with phosphate-buffered saline (PBS), while uninfected mice were used as negative control. Levels of CD103 and forkhead box P3 (FoxP3) expression were measured by direct immunofluorescense, while plasma IFN-γ and TNF-α level were determined using enzyme-linked immunosorbent assay (ELISA). Results: All treated groups showed an increase in parasitemia from day 2 to day 6 p.i, which was significant at day 2 p.i (p = 0.001), with the group receiving B. longum displaying the lowest degree of parasitemia. Significant reduction in plasma IFN-γ and TNF-α levels was observed in the group receiving B. longum (p = 0.022 and p = 0.026, respectively). The CD103 and FoxP3 expression was highest in the group receiving B. longum (p = 0.01 and p = 0.02, respectively). Conclusion: B. longum showed the best protective effect against Plasmodium infection by reducing the degree of parasitemia and modulating the gut immunity. This provides a basis for further research involving probiotic supplementation in immunity modulation of infectious diseases.

The colonic microbiome has been recognized as a potential source of next-generation of probiotics to prevent and treat human disease, including inflammatory bowel disease (IBD). The aim of this study was to evaluate the anti-inflammatory potential of a large strain collection of human colonic anaerobic bacteria isolated from healthy human donors. We used human peripheral blood mononuclear cells (PBMCs) from different donors as a model for evaluating the immunomodulatory effects of the strains and measured the balance between pro-and anti-inflammatory cytokine secretion. Additionally, we devised an assay to test the potential of the strains to modulate cytokine responses by co-stimulation with heat-inactivated bacteria (HIB). We also assessed the capacity of bacterial strains to induce nuclear factor-kappaB (NF-κB) signalling via specific Toll-like receptors (TLRs) reporter cell assays. Moreover, murine macrophage RAW 264.7 cells were used to assess nitric oxide release caused by stimulation with these colonic bacteria. We found that the immune profile of colonic anaerobic bacteria is mostly strain specific and there appear to be no general trends associated with a specific species, although some species may show similar immune profiles. The bacterial strains could be categorised into one of three main immune profiles, namely immunostimulatory, immunomodulatory and immunosuppressive or 'silent' profiles. This research identified new immune phenotypes/profiles of gut bacteria that warrant further study in vivo.