**Author details**

treated with mercury, carbon tetrachloride, arsenicals, and bismuth; at present, an important number of agents have shown to be efficacious against *Giardia* in vitro and clinically. Nevertheless, current investigations try to establish an appropriate treatment regimen in giardiasis, but none of them appear to fulfill most of the criteria for an ideal drug. In fact, giardiasis is regularly considered an easily treated infection, but at times, due to treatment failure, re-infection or postinfection syndromes can have a huge impact on quality of life of the patient, which is why it is important to know at least six different classes of drugs, with

The 5-nitroimidazole (5-NI) derivatives remain the most frequently prescribed drugs, as well as metronidazole, tinidazole, and secnidazole. In spite of their efficacy, the treatment with these drugs is associated with several adverse effects, which are not always tolerable such as headache, metallic or bitter taste in mouth, nausea, vomiting, diarrhea, dizziness, general body discomfort, loss of appetite, etc. Whereas medical opposition may limit the use of some of them in singular cases, as in pediatrics, where their dose requirements make difficult the administration of tablet formulations to children. Finally, in the follow-up of some patients after treatment to evaluate the response to antigiardial drugs, a therapeutic failure is identi-

Nitazoxanide is a new very broad spectrum 5-nitrothiazolyl derivative with a potentially useful activity against a range of biological agents. The effect of nitazoxanide in *Giardia* trophozoite includes ultrastructural changes in the cell morphology, swelling, and the formation of large empty areas in the cytoplasm and the disruption of the plasma membrane. An overall response rate of 75–94%, usually well tolerated, and a few adverse effects are the reason to

Some patients, who are being treated with the standard treatment that cures other patients, can continue with symptoms. In these cases, there are possibilities of different situations, including drug resistance, cure followed by reinfection, and also noncompliance and post*-Giardia* lactose intolerance, because when a drug-resistant giardiasis is identified, the stage changes and it is necessary to use another antigiardial compound with a different mechanism

When there is a resistant *Giardia*, some therapeutic strategies could be used, since increasing the alternative dose and/or duration of the same one, changing another antigiardial, or using a drug combination might exert the synergistic effects. For this reason, the combination of the therapy should be reserved when single primary agents have failed to clear the infection. However, it also should be considered that administration of two or three drugs may have more profound physiological consequences, alter the intestinal microbiota, and increase the

The interest in *Giardia* infection studies have been raising since its inclusion in the World Health Organization (WHO) in the Neglected Diseases Initiative in 2004 [9, 19]. In the same

different mechanisms, indication, and contraindications [1, 2, 21].

fied [4, 7, 21, 22].

8 Current Topics in Giardiasis

choose this medicament [1, 22].

of action or a drug combination [1, 2, 4].

**8. Control and prevention**

drug-related adverse events and health care costs [8, 9, 22].

Alfonso J. Rodríguez-Morales1,2,3,4\*, Adriana M. Trujillo1 , Jorge A. Sánchez-Duque1 and Ángel A. Escobedo3,4,5

\*Address all correspondence to: arodriguezm@utp.edu.co

1 Public Health and Infection Research Group, School of Medicine and School of Veterinary Medicine and Zootechnics, Faculty of Health Sciences, Universidad Tecnológica de Pereira, Pereira, Risaralda, Colombia

2 Committee on Zoonoses and Haemorrhagic Fevers, Asociación Colombiana de Infectología, Bogotá, DC, Colombia

3 Working Group on Zoonoses, International Society for Chemotherapy, Aberdeen, United Kingdom

4 Committee on Clinical Parasitology, Pan-American Association of Infectious Diseases, Panama City, Panama

5 Department of Parasitology, Academic Paediatric Hospital "Pedro Borrás," La Habana, Cuba
