Giardiasis

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Last reviewed: 4 May 2025

Last updated: 03 Jan 2025

Giardiasis symptoms vary from asymptomatic passage of cysts to acute self-limiting diarrhoea or chronic diarrhoea. It is associated with growth restriction in children.

Diagnosis is by detection of cysts or trophozoites in a stool sample or by molecular-based detection of antigens or parasite-specific nucleic acids.

Microscopy with direct fluorescent antibody testing is the gold standard for diagnosing giardiasis.

Tinidazole, metronidazole, or nitazoxanide is recommended as first-line treatment.

Transmission is via the faecal-oral route. Personal hygiene is key to prevention.

Definition

Giardiasis is an enteric infection caused by a eukaryotic, flagellated, binucleated protozoan parasite called Giardia duodenalis (formerly known as Giardia lamblia or Giardia intestinalis).[1] First described in 1681, it is a major cause of diarrhoeal disease in human beings and other mammals.[2][3] Children and immunocompromised people may present with weight loss and faltering growth, or other developmental impairments, due to gut dysfunction and nutritional deficiencies.[4]

História e exame físico

Principais fatores diagnósticos

diarrhoea
frequent belching

Detalhes completos

Outros fatores diagnósticos

abdominal bloating and discomfort
malaise
weight loss
nausea and vomiting

Detalhes completos

Fatores de risco

contaminated water/food
domestic animals living in or around the house
hypogammaglobulinaemia
young age
male sex
day-care centre attendance
oral-anal sexual contact
recent antibiotic use

Detalhes completos

Investigações diagnósticas

Primeiras investigações a serem solicitadas

direct fluorescence antibody (DFA) test
enzyme-linked immunosorbent assay
nucleic acid amplification test, polymerase chain reaction of stool sample
stool microscopy
FBC

Detalhes completos

Investigações a serem consideradas

Lateral flow immunoassay (e.g., ImmunoCard STAT!)
duodenal aspirates and biopsies
string test (EnteroTest)

Detalhes completos

Algoritmo de tratamento

AGUDA

non-pregnant adult or child

pregnant; first trimester

pregnant; second or third trimester

CONTÍNUA

treatment failure or resistance

Colaboradores

Autores

Luther A. Bartelt, MD

Assistant Professor of Medicine

University of North Carolina School of Medicine

Division of Infectious Diseases

Chapel Hill

Declarações

LAB is reimbursed by UpToDate for authorship. LAB has received funding from the National Institutes of Health. LAB is the author of two articles cited in this topic.

Agradecimentos

Dr Luther Bartelt would like to gratefully acknowledge Dr Fida Khan and Dr Musaddiq Waheed, previous contributors to this topic.

Declarações

FK and MW declared that they had no competing interests.

Revisores

Zana Nikolla, MD

Faculty of Medicine

University of Tirana

Tirana

Albania

Declarações

ZN declares that she has no competing interests.

Rodney Adam, MD

Professor of Medicine and Immunobiology

University of Arizona

Tucson

Declarações

RA declares that he has no competing interests.

Referências

Nossas equipes internas de editoria e de evidências trabalham em conjunto com colaboradores internacionais especializados e pares revisores para garantir que forneçamos acesso às informações o mais clinicamente relevantes possível.

Principais artigos

Center for Disease Control and Prevention. CDC Yellow Book 2024: health information for international travel. Section 5: travel-associated infections & diseases - giardiasis. May 2023 [internet publication].Texto completo

Centers for Disease Control and Prevention. Giardia: about Giardia infections. May 2024 [internet publication].Texto completo

Shane AL, Mody RK, Crump JA, et al. 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea. Clin Infect Dis. 2017 Nov 29;65(12):e45-80.Texto completo Resumo

Artigos de referência

Uma lista completa das fontes referenciadas neste tópico está disponível para os usuários com acesso total ao BMJ Best Practice.

Diagnósticos diferenciais
- Rotavirus or other viral gastroenteritis
- Functional diarrhoea
- Coeliac disease
Mais Diagnósticos diferenciais
Diretrizes
- CDC Yellow Book: health information for international travel - giardiasis
- Infectious diarrhea: guideline for investigation
Mais Diretrizes
Folhetos informativos para os pacientes
Diarrhoea in adults
Mais Folhetos informativos para os pacientes
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Giardiasis

Summary

Definition

História e exame físico

Principais fatores diagnósticos

Outros fatores diagnósticos

Fatores de risco

Investigações diagnósticas

Primeiras investigações a serem solicitadas

Investigações a serem consideradas

Algoritmo de tratamento

non-pregnant adult or child

pregnant; first trimester

pregnant; second or third trimester

treatment failure or resistance

Colaboradores

Autores

Luther A. Bartelt, MD

Declarações

Agradecimentos

Declarações

Revisores

Zana Nikolla, MD

Declarações

Rodney Adam, MD

Declarações

Referências

Principais artigos

Artigos de referência

Uma lista completa das fontes referenciadas neste tópico está disponível para os usuários com acesso total ao BMJ Best Practice.

Diagnósticos diferenciais

Diretrizes

Folhetos informativos para os pacientes

Conectar-se ou assinar para acessar todo o BMJ Best Practice

Conectar-se ou assinar para acessar todo o BMJ Best Practice

Conectar-se para acessar todo o BMJ Best Practice