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Variable virulence of isolates of Giardia lamblia in mice
Abstract:
Groups of inbred mice were inoculated intraoesophageally with Giardia lamblia cysts isolated from the stools of 15 patients with various clinical conditions: symptomatic diarrhoeic, symptomatic non-diarrhoeic and asymptomatic cyst carriers. The virulence of these isolates was studied in terms of two-hour cyst excretion rate and trophozoite counts in the duodenum. The basic pattern of the cyst excretion was similar in all the groups: cysts appeared in the stools by Day 3 +/- 1, reaching a maximum by Day 11 +/- 2. There was then a gradual decline until Day 23 +/- 2, with a low output until Day 31 post-inoculation. However, statistically significantly higher numbers of cysts were excreted by animals which had received cysts isolated from symptomatic diarrhoeic patients than by mice which received cysts from symptomatic non-diarrhoeic or asymptomatic cases. Identical results were obtained with the trophozoite counts. Haemagglutinating (HA) antibodies appeared after Day 11 post-inoculation in each group regardless of different cyst isolates, and the HA titre increased until Day 31 post-inoculation. The results indicate that variable symptomatology in patients could be due to variation in the virulence of the parasite.
Insights
Virulence of Giardia lamblia varies among isolates, impacting human infections. Cysts from symptomatic diarrheal patients showed higher excretion and duodenal counts in mice, suggesting parasite virulence drives varied clinical outcomes.
Area of Science:
- * Infectious Diseases
- * Parasitology
- * Microbiology
Background:
- * Giardia lamblia is a significant cause of diarrheal disease worldwide.
- * The clinical presentation of giardiasis varies widely among infected individuals.
- * Understanding the factors contributing to this variability is crucial for effective treatment and prevention.
Purpose of the Study:
- * To investigate the virulence of Giardia lamblia isolates from patients with different clinical conditions.
- * To correlate parasite excretion and duodenal load with patient symptomatology.
- * To assess the host immune response to different parasite isolates.
Main Methods:
- * Inbred mice were intraesophageally inoculated with Giardia lamblia cysts from symptomatic diarrheic, symptomatic non-diarrheic, and asymptomatic patients.
- * Cyst excretion rates in stools and trophozoite counts in the duodenum were monitored.
- * Haemagglutinating (HA) antibody responses were measured post-inoculation.
Main Results:
- * Mice inoculated with cysts from symptomatic diarrheic patients exhibited significantly higher cyst excretion and duodenal trophozoite counts.
- * A consistent pattern of cyst excretion was observed across all groups, peaking around Day 11 post-inoculation.
- * Haemagglutinating antibodies appeared by Day 11 and increased through Day 31, irrespective of the isolate's origin.
Conclusions:
- * The virulence of Giardia lamblia isolates varies, directly influencing the severity of infection.
- * Differences in parasite virulence are a key factor contributing to the diverse clinical manifestations of giardiasis.
- * Further research into parasite factors influencing virulence is warranted.