After human infection with Giardia, those without clinical symptoms are called carriers. The main symptoms of this disease include abdominal pain, diarrhea, abdominal distension and fullness, vomiting, fever, and anorexia. Typical patients present with a malabsorption syndrome primarily characterized by diarrhea, with watery stools that are large in volume, foul-smelling, and free of pus or blood. Pediatric patients may experience malnutrition such as anemia due to diarrhea, leading to growth retardation. If treatment is deficient, the condition often progresses to a chronic stage, manifesting as periodic loose stools, recurrent episodes, extremely foul-smelling stools, and a course that can last for several years.

bubble_chart Epidemiology

The distribution is global, with particularly severe cases in the former Soviet Union and near-epidemic levels in the United States. Developing countries have approximately 250 million infected individuals. In China, the distribution is also widespread, with infection rates ranging from 0.48% to 10% across regions, higher among children than adults, and incidence peaking during summer and autumn.

bubble_chart Pathological Changes

When the parasite Chinese Taxillus Herb is present in the biliary system, it may cause cholecystitis or cholangitis. Symptoms such as upper abdominal pain, loss of appetite, hepatomegaly, and fat metabolism disorders may occur. The pathogenic mechanism of Giardia is not yet fully understood, but it is generally believed that the patient's condition is related to multiple factors such as parasite virulence, host response, and symbiotic internal environment. Mechanical obstruction by the parasites, competition for nutrients, stimulation and injury caused by trophozoites attaching to the intestinal membrane via suckers, and the synergistic effects of intestinal bacteria can all contribute to varying degrees of intestinal dysfunction. The host's immune status is particularly crucial in determining the severity of clinical symptoms. For example, patients with hypogammaglobulinemia, immunodeficiency, or Acquired Immune Deficiency Syndrome are more prone to severe infections.

The main symptoms of this disease include abdominal pain, diarrhea, abdominal distension and fullness, vomiting, fever, and anorexia. Typical patients present with a malabsorption syndrome primarily characterized by diarrhea, with watery stools that are voluminous, foul-smelling, and free of pus or blood. In pediatric patients, diarrhea can lead to malnutrition such as anemia, resulting in growth retardation.

bubble_chart Auxiliary Examination

1. Pathogen Diagnosis

(1) Stool Examination Trophozoites are examined using the saline smear method, while cysts are examined via iodine-stained smears. Formalin-ether sedimentation or zinc sulfate flotation can also be used to detect cysts. Typically, cysts are examined in formed stools, whereas trophozoites are sought in watery or loose stools. Due to the intermittent nature of cyst formation, stool examinations should be repeated every other day for at least three consecutive times.

(2) Duodenal Fluid or Bile Examination This method is used for cases with repeatedly negative stool tests to improve the positive detection rate.

(3) Entero-Test Capsule Method The subject swallows a capsule containing a nylon string, with the free end left outside the mouth. After the capsule dissolves, the nylon string loosens and extends, reaching the duodenum and jejunum within 3–4 hours. Trophozoites adhere to the nylon string, which is then slowly withdrawn, and the attached material is scraped off for microscopic examination.

2. Immunological Diagnosis

As an auxiliary diagnostic method, it primarily includes enzyme-linked immunosorbent assay (ELISA), indirect fluorescent antibody test (IFA), and counterimmunoelectrophoresis (CIE). Among these, ELISA is simple, easy to perform, and has a high detection rate (92%–98.7%), making it suitable for epidemiological surveys.

Examination of duodenal drainage fluid for trophozoites is of significant importance in the diagnosis of this disease.

bubble_chart Treatment Measures

Commonly used drugs for treatment include metronidazole, albendazole, and tinidazole. In recent years, reports indicate that praziquantel at 60mg/kg for two consecutive days is also effective. Important preventive measures include completely curing patients and carriers, maintaining food hygiene, and strengthening water source protection. Travelers should boil their drinking water before consumption.

bubble_chart Cure Criteria

After thorough treatment, the absence of clinical symptoms or signs, as well as no cysts found in stool examinations, indicates a cure.

bubble_chart Prognosis

The prognosis of this disease is good, with no sequelae.

bubble_chart Prevention

To completely cure patients and carriers, maintaining food hygiene and strengthening water source protection are important measures to prevent this disease. Travelers should boil their drinking water before consumption.