Giardiasis: An Overview

BACKGROUND

Giardiasis is an important cause of waterborne and foodborne diarrhea, daycare center outbreaks, and traveler's diarrhea.

OBJECTIVE

The study aimed to provide an update on the evaluation, diagnosis, and treatment of giardiasis.

METHODS

A PubMed search was completed in Clinical Queries using the key terms "giardiasis", "Giardia lamblia", "Giardia duodenalis" and "Giardia intestinalis". The search strategy included metaanalyses, randomized controlled trials, clinical trials, observational studies, and reviews. The search was restricted to the English literature. Patents were searched using the key term "giardiasis" from www.freepatentsonline.com.

RESULTS

Giardiasis is caused by the protozoan parasite Giardia lamblia. The parasite is transmitted by the fecal-oral route, frequently through ingestion of contaminated water and food or person-to person transmission. Risk factors for infection include children in day-care settings, child-care workers, institutionalized individuals, travelers in endemic areas, ingestion of contaminated or recreational water, immunodeficiency, cystic fibrosis, and oral-anal sex. Approximately 50 to 75% of infected children are asymptomatic. Other children present acute or chronic diarrhea. Direct fluorescent antibody tests that detect intact organisms, enzyme immunoassays that detect soluble antigens, and multiplex real-time polymerase chain reaction assays that detect specific genes of the parasite in stool samples have improved sensitivity and specificity compared with microscopic examination of stool specimens for the detection of Giardia trophozoites or cysts. Drugs used in the treatment of symptomatic giardiasis are reviewed in this study. Moreover, recent patents related to the management of giardiasis are also discussed.

CONCLUSION

Metronidazole, tinidazole, and nitazoxanide are drugs of choice. Resistance to common antigiardial drugs has increased in recent years, therefore, the search for new molecular targets for antigiardial drugs is urgently needed. In general, treatment of asymptomatic carriers is not recommended. Purification of water supply is an important preventive measure.

High mortality in adults hospitalized for active tuberculosis in a low HIV prevalence setting

BACKGROUND

This study aims to evaluate the outcomes of adults hospitalized for tuberculosis in a higher-income region with low HIV prevalence.

METHODS

A retrospective cohort study was conducted on all adults hospitalized for pulmonary and/or extrapulmonary tuberculosis in an acute-care hospital in Hong Kong during a two-year period. Microscopy and solid-medium culture were routinely performed. The diagnosis of tuberculosis was made by: (1) positive culture of M. tuberculosis, (2) positive M. tuberculosis PCR result, (3) histology findings of tuberculosis infection, and/or (4) typical clinico-radiological manifestations of tuberculosis which resolved after anti-TB treatment, in the absence of alternative diagnoses. Time to treatment ('early', started during initial admission; 'late', subsequent periods), reasons for delay, and short- and long-term survival were analyzed.

RESULTS

Altogether 349 patients were studied [median(IQR) age 62(48-77) years; non-HIV immunocompromised conditions 36.7%; HIV/AIDS 2.0%]. 57.9%, 16.3%, and 25.8% had pulmonary, extrapulmonary, and pulmonary-extrapulmonary tuberculosis respectively. 58.2% was smear-negative; 0.6% multidrug-resistant. 43.4% developed hypoxemia. Crude 90-day and 1-year all-cause mortality was 13.8% and 24.1% respectively. 57.6% and 35.8% received 'early' and 'late' treatment respectively, latter mostly culture-guided [median(IQR) intervals, 5(3-9) vs. 43(25-61) days]. Diagnosis was unknown before death in 6.6%. Smear-negativity, malignancy, chronic lung diseases, and prior exposure to fluoroquinolones (adjusted-OR 10.6, 95%CI 1.3-85.2) delayed diagnosis of tuberculosis. Failure to receive 'early' treatment independently predicted higher mortality (Cox-model, adjusted-HR 1.8, 95%CI 1.1-3.0).

CONCLUSIONS

Mortality of hospitalized tuberculosis patients is high. Newer approaches incorporating methods for rapid diagnosis and initiation of anti-tuberculous treatment are urgently required to improve outcomes.