April 27, 2023 Author : Saraiva da Cunha Giardiasis is an intestinal infection caused by a protozoan parasite , Giardia duodenalis , also known as Giardia lamblia or Giardia intestinalis : This parasite is not visible to the naked eye; It affects people, particularly children under age 5, and some animals, including companion and livestock species. Giardia exists all over the world but is more frequent in regions with poor basic sanitation conditions. It is estimated that more than 300 million cases occur worldwide each year. In Europe, in 2019, 18004 cases of giardiasis were confirmed; Globally, Giardia is the third most important cause of diarrhea in children under 5 years old. Giardiasis is a mandatory reporting disease in Portugal . In 2018, the last year for which records are published in Portugal, 37 cases were notified, almost 50% of which in the metropolitan regions of Lisbon and Porto, and 43% in children under 14 years of age. How does the infection occur and how is it transmitted In infected people (and animals), the parasite lives and multiplies in the intestines, in the form of trophozoites, and is excreted in the feces, in the form of cysts. Outside the body, Giardia cysts are infectious and very resistant, surviving for months in water or soil, especially in low temperature and high humidity conditions. The infection happens when cysts of the parasite are ingested , which can happen in 3 main ways: With contaminated water, which is the most common; With raw food or food that has been contaminated after cooking; By fecal-oral transmission, that is, when you have contact with someone, something or some surface contaminated by residues of infected feces, even if not visibly, and then you bring your hands to your mouth, inadvertently, ingesting the parasite. A higher risk of infection exists in: Children, especially those who have daily contact with other children and still wear diapers or are in the process of leaving diapers; People who do not have access to clean water, as the most common source of infection is contaminated water; People with immune compromise, whether due to illness or immunosuppressive treatment; Travelers to regions with high risk; People who have unprotected anal or oral-anal sex. Transmission of Giardia from companion animals to people is not common. Giardia has 8 different strains, two infect people and animals, but the remaining six only infect animals; Even so, it is very important to always maintain good hygiene and cleaning practices for the facilities, beds and toys for pets. Symptoms of giardiasis In some people, the infection has no symptoms. However, they are carriers of the parasite and eliminate it in their feces, that are a source of infection for others. More often, symptoms of giardiasis begin 1-2 weeks after the infection , and include: Diarrhea, often with a greasy appearance and a very unpleasant odor; Stomach and abdominal pain, cramps and gas; Malaise, discomfort and tiredness; Nausea and vomiting; Weight loss. Giardiasis also has a chronic form , in which crises of symptoms can follow, and which in children can cause growth problems associated with poor absorption of different nutrients. Diagnosis and treatment In addition to the symptoms, the reported history is very important for the diagnosis of giardiasis, for example: When it comes to a child, if there is daily contact with other children, as contagion among these is facilitated by playing and sharing objects; If the patient works with children or there are children in the family; If there have been recent trips to regions where the infection is more common; If untreated water was used to drink. The infection can be confirmed by analyzing feces for the parasite . However, the elimination of the parasite in the feces may not be constant, so, as a rule, it is necessary to collect several samples to be sure of a conclusive result. In some cases, an upper digestive endoscopy may also be required. Treatment of giardiasis is done with antiparasitic drugs , usually with a complete recovery. In children, if they are dehydrated, treatment with fluids and electrolytes may also be required. Since asymptomatic carriers can be a source of infection, when a case of giardiasis is diagnosed, cohabitants and people in close contact should also undergo treatment if any of the following circumstances occur: Outbreak control, for example in kindergartens; Cohabitation with pregnant women; Cohabitation with immunosuppressed people. Even after successfully treated giardiasis, some people may continue to experience digestive problems over the years, including complications such as lactose intolerance and irritable bowel syndrome. Prevention of giardiasis There are no vaccines or medications to prevent giardiasis. Prevention is based on measures that reduce the risk of becoming infected , for example: Washing hands frequently , and always after using the bathroom or changing diapers, before preparing food and eating or drinking, after handling or caring for animals; Do not use untreated water (for example, from wells, fountains) for drinking or for washing fruit or vegetables without first boiling it for at least 10 minutes or treating it with specific disinfectant products; Try not to drink water when bathing or swimming in pools, ponds or other places. In high-risk countries do not eat unpeeled fruit or raw vegetables, do not drink non-bottled water, do not use ice in drinks, use bottled water to brush your teeth, do not eat undercooked food. Avoid unprotected sex . Sources Centers for Disease Control and Prevention. Giardia and pets . Leder K, Weller PF. Giardiasis: epidemiology, clinical manifestations and diagnosis. www.uptodate.com Serviço Nacional de Saúde. Doenças de Declaração Obrigatória . Meet the infeccious diseases clinical team from Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
