Disease Biomarkers of Giardiasis

Table 2

Diagnostic strength of the identified biomarkers.

Type of test	Biomarker detected	Diagnostic strength	Strength/limitation in study	Reference
Enzyme-linked immunosorbent assay (ELISA)	Hsp70	The concentration of Hsp70 in fecal samples of patients with giardiasis was sevenfold higher than that in the control group	This study is the first to reveal the presence of Hsp70 in fecal matter of patients infected with Giardia parasites	[35]
	GSA 65	ELISA-GSA65 can detect giardiasis in at least 30% more cases than microscopy examination, with sensitivity and specificity ranging from 95% to 100%	Due to the lower level of antigen in the trophozoites that appear in the feces of infected patients, a very potent antiserum against the trophozoites that can detect such antigens was needed	[41]
	P-selectin	The level of P-selectin in male and female was , respectively, compared to that in the control group (), respectively	—	[55]
	Calprotectin	The concentration of calprotectin in male (0.13907 ng/mL) and female patients (0.20530 ng/mL) infected with G. lamblia was significantly increased compared to that in the control group	—	[58]
	Trefoil factor 3 (TFF3)	The concentration of TFF3 in male (0.13907 ng/mL) and female patients (0.20530 ng/mL) infected with G. lamblia was significantly increased as compared to that in male (0.078864 ng/mL) and female (0.082629 ng/mL) patients in the control group	—	[58]
	Immunoglobulin G (IgG)	81% of 59 symptomatic giardiasis patients and 12% of 17 uninfected control subjects had circulating IgG antibodies to G. lamblia	The application of ELISA to screen large populations has been proven to be feasible and more sensitive than stool examination	[43]
	Immunoglobulin M; (IgM)	Both sensitivity and specificity were 96%	Useful in identifying patients with current infection	[44]
	Secretory IgA (SIgA) in saliva	Levels of secretory anti-Giardia IgA showed better specificity (95%) than sensitivity (77%)	The advantage of assays from saliva is that it is simple and noninvasive, suitable for sampling especially in children	[45]
		Levels of secretory anti-Giardia IgA showed better specificity (94%) than sensitivity (74%)	The noninvasive nature of collecting samples of saliva represents a clear advantage for studies in children	[46]
	Secretory IgA (SIgA) in milk	Most milk and saliva samples contained anti-Giardia antibodies (59% and 52%, respectively), with a mean sIgA content 50 times higher in milk than in saliva	Since the function of antibodies in breast milk can bind to and inactivate secreted enzymes, further experiments are needed to show if this is important during infection	[48]
	Ghrelin	Serum ghrelin concentration in giardiasis patients (33.245 ng/mL) was significantly lower than that in healthy group (50.102 ng/mL)	The study included a relatively small number of male patients only. A larger number of patients and a more comprehensive study are recommended	[55]
	Melatonin	Serum melatonin concentration was higher in the giardiasis patients (22.876 pg/mL) than in the healthy group (9.213 pg/mL)	The study included a relatively small number of male patients only. A larger number of patients and a more comprehensive study are recommended	[55]
Gas chromatography - mass spectrometry	1. 2,2,4,4- tetramethyloctane, acetic acid and 2,2,4,6,6pentamethylheptane	These 3 VOCs had a significantly greater prevalence amongst Giardia cases (). AUROC analysis demonstrated a value of 0.902	A study needs to be performed on a larger patient population so that severity of the infection can be better assessed and compared	[71]
	Acetic acid, 1,4-dimethoxy-2,3-butanediol and 1,3-dimethoxy-2-propanol,	The volatile alcohols 1,3-dimethoxy-2-propanol and 1,4-dimethoxy-2,3-butanediol and acetic acid have important weights in the separation of patients with giardiasis, showing high loadings of 0.809, 0.781, and 0.682	Analysis of volatile substances has sufficient sensitivity to detect differences in volatile profiles in the feces of patients with and without G. duodenalis infection	[72]
Polymerase chain reaction (PCR)	miR5 and miR6	The likelihood ratios for miR5 based on 100% sensitivity and specificity have a threshold cycle while the likelihood ratios for miR6, based on 66.6% sensitivity and 90% specificity, have a threshold cycle average of 30.0	Relatively small numbers in both the experimental and control groups as well as assessment were limited to only two miRNA molecules	[66]
Flow cytometry	Recombinant VSP3 and recombinant VSP5	The sensitivity and specificity value of VSP5 and VSP3 on cumulative assays of IgG/IgM were 100% while the sensitivity and specificity value of IgA-VSP5 and VSP3 cumulative assays were 80% and 100%, respectively	The samples represent many Giardia strains as it examines the humoral immune response in giardiasis patients in nonendemic areas	[12]
	VSP 5G8	GS-5G8 (+) strain infection induced an antibody response that recognized more than 50% of the GS-5G8 (+) trophozoite population and (<90%) of GS-5G8 (+) during reinfection	Lack of knowledge for the variant shift of G. lamblia GS-5G8 (+) in culture or whether it has lost its ability to change to another VSP	[20]