Diagnosis of Human Giardiasis by Coprological Sandwich ELISA using Paramagnetic Nanoparticles

Abstract

Giardiasis is a global public health problem, with 300 million people infected each year. Giardia lamblia, a flagellated protozoan, is among the most common intestinal protozoa and is the most frequent parasitic agent of gastroenteritis worldwide. It is considered to be one of the most common nonviral nonbacterial cause of diarrhea worldwide. The world health organization (WHO) considers diarrheal disease the second most common cause of morbidity and mortality in children in the developing world. Giardiasis is endemic in all regions of the world with a prevalence range from 2-7% in developed countries to 20-30% in most developing countries.It constitutes a significant public health problem in Egypt especially in rural areas. Giardia has a simple life cycle that comprises a resistant infectious cyst stage and a mobile disease-causing trophozoite, both forms are found in faeces. Giardia cyst can be transmitted directly, through the faecal-oral route, or indirectly, by ingestion of contaminated water or food. The clinical features of giardiasis range from acute or chronic diarrhea, abdominal pain, vomiting,flatulence,nausea, weight loss, to absence of symptoms and signs. Because of the increased risk of side effects and the possible emergence of antibiotic-resistant organisms, the most beneficial way in treating giardiasis naturally may be through a combination of both nutritional interventions and phytotherapeutic agents. Microscopic examination of stool specimens is generally accepted as the gold standard for the diagnosis of parasitic diseases, in comparison with new tests, and it has the advantage of being inexpensive compared to antigen detection tests. Although microscopy has the advantage of low cost and ability to simultaneously detect other gastrointestinal parasite, the disadvantages of this method is that G. lamblia cysts are small and similar in appearance to many pseudoparasites such as yeast. Also, the trophozoites break up rapidly in the stool, so cannot be used to measure the severity of infection and the sensitivity of microscopy is quite low due to the intermittent excretion of Giardia cystsso two or three specimens collected on different days should be analyzed. Recently, ELISA has been considered as cost effective diagnostic method that can detect small quantities of coproantigens of parasite, even in mild infection, and diagnosed even if the live parasite is absent in the feacal sample. It can also detect soluble antigens in the faecesand can detect Giardia