Cyclospora

Essentials of Diagnosis • Patients present with watery diarrhea, which is usually self-limited in immunocompetent patients but may be prolonged in the immunocompromised patient. •A history of travel to areas such as Nepal, Haiti, and Peru, a history of berry consumption, or community outbreak of diarrhea may increase suspicion of diagnosis. • Acid-fast stain of stool specimens reveals abundant oocysts. General Considerations Cyclospora is a coccidian that had been described as a “large cryptosporidium” or “cyanobacterium-like body” before being confirmed as a member of the phylum Apicomplexa in 1993. The life cycle in humans has not been fully detailed. The organism has been shown to infect jejunal enterocytes. Similar to Isospora, …

Continue Reading...

Cryptosporidium: Clinical Syndromes

Enteric cryptosporidiosis is the most common clinical presentation in patient populations. In addition, immunocompromised patients may present with cholecystitis or respiratory infections attributed to C parvum (Box 1). Asymptomatic infection has also been reported. 1. ENTERIC CRYPTOSPORIDIOSIS Clinical Findings A. Signs and Symptoms. An average of 5-7 days passes from oocyst ingestion to symptom onset. Symptoms are similar in both immunocompetent and immunocompromised patients but are prolonged and considerably more severe in compromised patients. Patients complain of watery diarrhea in variable quantities of = 25 L/day leading to significant dehydration. Abdominal cramps, malaise, low-grade fever, and anorexia are frequently reported. Nausea, vomiting, myalgia, headache, and weight loss may also occur. Symptoms …

Continue Reading...

Pathogenic Amebas

ENTAMOEBA HISTOLYTICA & ENTAMOEBA DISPAR Essentials of Diagnosis • Patient living in or having traveled to endemic area increases risk. • Frequent loose stools with blood and mucus. • Demonstration of cyst or trophozoite on stool wet mount or in biopsy specimen. • Serology positive within 7-10 days of infection, may remain positive for years after infection resolved. • Monoclonal antibodies and polymerase chain reaction emerging; may help differentiate E histolytica and E dispar. General Considerations A. Epidemiology. There are numerous distinct species of ameba within the genus Entamoeba, and the majority of these do not cause disease in humans. E histolytica is a pathogenic species that is capable of causing …

Continue Reading...

Amebic Liver Abscess

Clinical Findings A. Signs and Symptoms. Amebic liver abscess is the most common extraintestinal manifestation of amebiasis. Patients may note right-upper-quadrant pain that is either dull or pleuritic in nature. Often pain is referred to the right shoulder. Less than 50% of patients have an enlarged liver. In the acute setting, patients typically manifest fever. If symptoms have been present for > 2 weeks, fever is present in less than half of patients. Respiratory symptoms, such as cough, can occur even in the absence of pulmonary disease and may be the only complaint. In the subacute setting, weight loss is common. Diarrhea is found in less than one-third of patients with …

Continue Reading...

Intestinal Disease

Clinical Findings A. Signs and Symptoms. Of patients infected with E histolytica, > 90% are asymptomatic carriers who are colonized with the organism and pass cysts in the stool. This carrier state often resolves without treatment, although relapses and reinfection are common. Acute amebic colitis usually presents with several weeks of lower abdominal pain and diarrhea with frequent loose to watery stools containing blood and mucus. Most patients are afebrile. Significant volume depletion is uncommon. Chronic amebic colitis is characterized by low-grade inflammation resulting in intermittent bloody diarrhea and abdominal pain over a period of months to years. It is often difficult to distinguish chronic disease from inflammatory bowel disease, and …

Continue Reading...

Toxoplasma Gondii

General Considerations A. Epidemiology. Toxoplasma gondii infection, or toxoplasmosis, is a zoonosis (the definitive hosts are members of the cat family). The two most common routes of infection in humans are by oral ingestion of the parasite and by transplacental (congenital) transmission to the fetus. Ingestion of undercooked or raw meat that contains cysts or of water or food contaminated with oocysts results in acute infection. In humans, the prevalence of toxoplasmosis increases with age. There are also considerable geographic differences in prevalence rates (eg, 10% in Palo Alto, CA; 15% in Boston, MA; 30% in Birmingham, AL; 70% in France; = 90% in El Salvador). Differences in the epidemiology of …

Continue Reading...

Toxoplasma Gondii: Treatment

A. Infection in Immunocompetent Adults and Children. Immunocompetent adults and children with toxoplasmic lymphadenitis do not require treatment unless symptoms are severe or persistent. Infections acquired by laboratory accident or transfusion of blood products are potentially more severe, and these patients should always be treated. The combination of pyrimethamine, sulfadiazine, and folinic acid for 4-6 weeks is the most commonly used and recommended drug regimen (Box 2). Treatment should be administered for 2-4 weeks, followed by reassessment of the patient’s condition. The decision to treat active toxoplasmic chorioretinitis should be based on the results of an examination performed by an ophthalmologist. Pyrimethamine and sulfadiazine plus folinic acid are commonly used for …

Continue Reading...

Toxoplasma Gondii: Clinical Findings

Primary infection in any host often goes unrecognized. In ~ 10% of immunocompetent individuals, it causes a self-limited and nonspecific illness that rarely requires treatment. The most frequently observed clinical manifestation in this setting is lymphadenopathy and fatigue without fever; other manifestations include chorioretinitis, myocarditis, and polymyositis (Box 1). Reinfection occurs but does not appear to result in clinically apparent disease. In contrast to the usually benign course of the initial infection in immunologically intact hosts, the congenitally infected fetus and newborn and immunocompromised patients are at high risk for severe or life-threatening disease caused by this parasite. Congenital toxoplasmosis is the result of maternal infection acquired during gestation. Among immunologically …

Continue Reading...

Malaria and Babesia

PLASMODIUM SPP. • Exposure history, such as travel, recent transfusion, or living in close proximity to an international airport. • Nonfalciparum malaria: chills and fever spikes, followed by defervescence and fatigue; symptoms may be cyclic every 48-72 h. • Falciparum malaria: fever spikes and chills, often noncyclic and associated with rapidly progressive systemic symptoms. • Detection and identification of a Plasmodium species in a thick and thin blood smear, respectively. • Molecular detection of P falciparum’s histidine-rich protein by enzyme-linked immunosorbent assay (ELISA) or Plasmodium DNA by polymerase chain reaction (PCR) followed speciation by probe hybridization or DNA sequencing. General Considerations A. Epidemiology. Malaria, a disease of antiquity, was recognized by …

Continue Reading...

Babesia SPP.

Essentials of Diagnosis • Nonspecific clinical manifestations. • Exposure: tick exposure, blood transfusion, or both. • Morphologic, serologic, or molecular evidence of infection. General Considerations The members of the genera Babesia and Theileria are protozoan parasites. These organisms are of medical, veterinary, and economic importance. Babesia species cause disease in humans and animals. The genus Theileria is the etiologic agent of cattle fever in Eurasia and Africa; it has also been implicated in human disease. Common to both genera is an intra-erythrocytic phase. These organisms develop pear-shaped intra-erythrocytic ring forms and are therefore referred to as piroplasms. An exo-erythrocytic schizont stage has been demonstrated only for Theileria species. Babesia species were …

Continue Reading...
CLOSE
CLOSE