Protozoan co-infections and parasite influence on the efficacy of vaccines against bacterial and viral pathogens

Abstract

A wide range of protozoan pathogens either transmitted by vectors (Plasmodium, Babesia, Leishmania and Trypanosoma), by contaminated food or water (Entamoeba and Giardia), or by sexual contact (Trichomonas) invade various organs in the body and cause prominent human diseases, such as malaria, babesiosis, leishmaniasis, trypanosomiasis, diarrhea, and trichomoniasis. Humans are frequently exposed to multiple pathogens simultaneously, or sequentially in the high-incidence regions to result in co-infections. Consequently, synergistic or antagonistic pathogenic effects could occur between microbes that also influences overall host responses and severity of diseases. The co-infecting organisms can also follow independent trajectory. In either case, co-infections change host and pathogen metabolic microenvironments, compromise the host immune status, and affect microbial pathogenicity to influence tissue colonization. Immunomodulation by protozoa often adversely affects cellular and humoral immune responses against co-infecting bacterial pathogens and promotes bacterial persistence, and result in more severe disease symptoms. Although co-infections by protozoa and viruses also occur in humans, extensive studies are not yet conducted probably because of limited animal model systems available that can be used for both groups of pathogens. Immunosuppressive effects of protozoan infections can also attenuate vaccines efficacy, weaken immunological memory development, and thus attenuate protection against co-infecting pathogens. Due to increasing occurrence of parasitic infections, roles of acute to chronic protozoan infection on immunological changes need extensive investigations to improve understanding of the mechanistic details of specific immune responses alteration. In fact, this phenomenon should be seriously considered as one cause of breakthrough infections after vaccination against both bacterial and viral pathogens, and for the emergence of drug-resistant bacterial strains. Such studies would facilitate development and implementation of effective vaccination and treatment regimens to prevent or significantly reduce breakthrough infections.

The importance, benefits, and future of nanobiosensors for infectious diseases

“…Infectious agent research is crucial for understanding the spread of diseases through microorganisms like bacteria, viruses, fungi, protozoa, and parasites. 17 Recognizing and categorizing these agents help identify health hazards and develop effective prevention strategies. Tracing transmission variables and paths can help diagnose diseases, reducing the risk of major consequences or death.…”

Uncovering the diversity of pathogenic invaders: insights into protozoa, fungi, and worm infections

“…These pathogenic strains have evolved complex mechanisms for invasion and survival in the host. Protozoa frequently go through several sequential stages, that provide them the flexibility to take advantage of various tissues or hosts as they make their way through the challenging transition from existence to transmission, and the sickness often results in tissue damage and subsequent illness ( Zheng et al, 2020 ; Akoolo et al, 2022 ). An assortment of symptoms, from fever and anaemia to cognitive dysfunction and organ failure, can result from the chronic infectious disorders caused by infectious protozoan species that impact the blood, gastrointestinal system, liver, and brain ( Seed, 1996 ).…”

COVID-19 and Diarylamidines: The Parasitic Connection

“…However, exceptions do occur; for example, Plasmodium spp. infection prior to SARS-CoV-2 infection was reported to contribute to the disease’s poor prognosis and was seen to reduce the incidence of malaria in endemic regions [ 33 , 34 , 35 ]. Furthermore, additional investigations suggested that high exposure to malaria compared to low exposure prior to SARS-CoV-2 infection offered better protection against severe or critical COVID-19 [ 36 ].…”

“…Moreover, the authors proposed that vaccine memory was partially destroyed or the accessibility to those memories was prohibited by infection, further highlighting the need for malaria vaccine trials in areas where trypanosomiasis is prevalent. The influence of protozoan infection on bacterial and viral vaccination efficacy and the adaptive immune response is summarized in Figure 4 [ 34 ].…”

“…(C) Protozoan modulated vaccine antibody response against different viral pathogens; impact on breakthrough infections inconclusive. Adapted from Akoolo et al [ 34 ].…”