Diseases giardiasis

Problems of recent years involving listeriosis, salmonellosis, giardiasis and Legionnaire s disease have received attention, as have the re-emergence of tuberculosis and the importance of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). 

Space constraints do not allow detailed discussions of the world of parasites, and clinicians and students are directed to some excellent resources for further details on parasites and parasitic diseases.1,2 Discussion in this chapter will include those parasitic diseases that are more likely to be seen in the United States and will include gastrointestinal parasites (primarily giardiasis and amebiasis), protozoan infections (malaria and South American trypanosomiasis), some common helminthic... 

Giardiasis For the treatment of giardiasis caused by Giardia duodenalis (also termed Giardia lamblia) in adults and pediatric patients older than 3 years of age. Trichomoniasis For the treatment of trichomoniasis caused by Trichomonas vaginalis in female and male patients. Because trichomoniasis is a sexually transmitted disease with potentially serious sequelae, partners of infected patients should be treated simultaneously in order to prevent reinfection. 

Antibiotic therapy is justified where there is suspicion of giardiasis (metronidazole) and bismuth subsalicylate is effective in acute travellers diarrhoea, as are agents such as ciprofloxacin. In tropical areas where there is suspicion of amoebic disease metronidazole should be given early. 

Stool culture for pathogens, notably salmonel-lae and shigellae, and examination for the exotoxin of Clostridium difficile in pseudo-membranous colitis, are important considerations in acute disease. C. difficile requires oral vancomycin or metronidazole treatment, and giardiasis generally responds to metronidazole. 

Waterborne microorganisms are largely responsible for the transmission of diseases such as cholera, typhoid, dysentery, muscular paralysis (e.g., poliomyelitis), infectious hepatitis, gastroenteritis, giardiasis, cryptosporidiosis, and so forth. In a drinking-water potabilization procedure not all the microorganisms present in water need to be killed (sterilization), but only those disease-related (disinfection). Water disinfection can be achieved by chemical, physical, or mechanical action. Agents that provide chemical action for such purposes include ... 

Potential waterborne diseases that follow tsunamis include cholera diarrheal or fecal-oral diseases, such as amebiasis, cryptosporidiosis, cyclosporiasis, giardiasis, hepatitis A and E, leptospirosis, parasitic infections, rotavirus, shigellosis, and typhoid fever animal- or mosquito-borne illness, such as plague, rabies, malaria, Japanese encephalitis, and dengue fever (and the potentially fatal complication dengue hemorrhagic shock syndrome) and wound-associated infections and diseases, such as tetanus. Mental health concerns are another consequence of tsunami events. 

As Figure 2.13 shows, the cysts are excreted in feces that may survive in moist environments, which then, again, become available to infect another individual. Thus, the disease is contracted in practically the same way as giardiasis and cryptosporidiosis... 

Metronidazole is effective in the treatment of many protozoal diseases, notably trichomoniasis, amebiasis, schistosomiasis, strongyloidiasis, and giardiasis, and has been in use for over 20 years. 

Secondary lactose intolerance may occur as a result of reduced enzyme activity following diffuse intestinal damage from infections (giardiasis, bacterial overgrowth, or viral gastroenteritis), ulcerative colitis, celiac disease, and tropical sprue. This deficiency is usually reversible following recovery from the disorder. 

This is pathogenic flagellate which usually inhabits the duodenum and upper jejunum but may also be found in the gall bladder. The parasite occurs both in the trophozoite and encysted forms. The infection is acquired by consuming food or drink contaminated with cysts and, therefore, it is more prevalent in children than the adults. The clinical manifestations of the disease may include epigastric pain, nausea, flatulence and diarrhea. Acute giardiasis may be associated with steatorrhea and weight loss [49]. 

Wright SG. Giardiasis. In Strickland GT, ed. Tropical Medicine and Emerging Infectious Diseases, 8th ed. Philadelphia, Saunders, 2000 589-593. 

For several other protozoan diseases there is adequate chemotherapy the 5-nitroimidazoles (for example, metronidazole) for the treatment of amoebiasis, giardiasis and trichomoniasis, the hydroxy-naphthoquinone bupravaquone for theileriosis in cattle and other ungulates, and the polyene ionophores (for example monensin, lasalocid, narasin and salinomycin) for the prophylaxis of avian coccidiosis. However, improved therapies are required for some opportunistic parasites that cause disease in immunocompromised humans. Paromomycin and nitazoxanide have some effect in the treatment of cryptosporidiosis and albendazole appears to be effective for microsporidiosis caused by Encephalitizoon intestinalis. 

Clinical use Metronidazole is the drug of choice in severe intestinal wall disease and in hepatic abscess and other extraintestinal amebic disease. Metronidazole is commonly used with a luminal amebicide. Other important clinical uses of metronidazole include treatment of trichomoniasis, giardiasis, and infections caused by Gardnerella vaginalis and anaerobic bacteria (Bfragilis, C difficile). 

---