Pediatric emergency medicine trisk 581

GASTROINTESTINAL/GENITOURINARY Amebiasis Amebiasis, caused by the parasite E histolytica, is responsible for approximately 55,000 deaths/yr globally; it is the third most frequently isolated pathogen among returning travelers with infectious diarrhea Amebiasis is transmitted via fecal–oral contact with amebic cysts; humans are the only reservoir High-risk groups include foreign travelers, migrant workers, immunocompromised individuals, children in daycare centers, and prisoners Less than 20% of persons who consume infected cysts develop symptoms The spectrum of infection ranges from asymptomatic carriers to intestinal amebiasis, hepatic abscesses, or amebomas Intestinal amebiasis typically has an insidious onset consisting of weight loss, abdominal pain, and initially nonbloody progressing to dysentery Fever is rare Complications include intestinal ulcers, fulminant colitis, and perforation Hepatic amebic abscesses present clinically as fever, cough, tachypnea, hepatomegaly, and right upper quadrant pain with referred shoulder pain (the latter is more common in adults) Liver abscesses are the most common extraintestinal form of amebiasis Rupture of the abscess with peritoneal seeding can be fatal While drainage may be adjunctive to medical therapy, percutaneous drainage under controlled circumstances is optimal to prevent peritoneal seeding Other extraintestinal manifestations are rare, but may include pericardial, pleuropulmonary, cerebral, genitourinary, and cutaneous amebiasis Amebomas are annular lesions of cecum or colon that can mimic cancer or pyogenic abscesses These usually can be managed medically Diagnosis is made via visualization of cysts or trophozoites in stool (for colitis) or serum enzyme immunoassay (EIA) testing (for extraintestinal disease) PCR can differentiate E histolytica from related, nonpathogenic species CT can help identify extraintestinal manifestations Ancillary testing may reveal leukocytosis, anemia, or transaminitis Treatment of asymptomatic carriers is with paromomycin (25 to 35 mg/kg/day in three divided doses for days) or diloxanide furoate (20 mg/kg/day in three divided doses [maximum: 500 mg/dose] for 10 days) Treatment of colitis is with metronidazole (35 to 50 mg/kg/day divided into three doses for to 10 days; maximum: 750 mg/dose) Treatment of liver abscesses, ameboma, or moderate/severe intestinal amebiasis is with metronidazole and paromomycin Surgical intervention may be needed for patients with hepatic abscesses unresponsive to medical management or those with toxic megacolon Contact precautions are recommended Giardia Giardiasis is caused by Giardia intestinalis, a protozoan spread by fecal–oral transmission While humans are the primary reservoir, domesticated and wild animals can also be infected Most U.S outbreaks have been associated with contaminated drinking water, daycare facilities, and food handlers One-half to three-quarters of infections are asymptomatic Symptoms include malodorous watery, nonbloody diarrhea, flatulence, abdominal pain, and weight loss Anemia may be noted Children with humoral immunodeficiencies can develop chronic symptomatic infection The diagnosis is based on EIA or direct fluorescent antibody (DFA) assays, which have sensitivity and specificity far superior to identification of organisms in the stool Treatment is not needed for self-limited infections in normal hosts, and treatment of asymptomatic carriers is not recommended unless they live in the home with an immunocompromised person For patients requiring treatment, metronidazole (5 mg/kg every hours [maximum: 250 mg/dose for to days]), tinidazole (single dose, licensed for children years of age and older: 50 mg/kg [maximum: g]), or nitazoxanide (3-day course for children year of age and older: to years: 100 mg twice daily, to 11 years: 200 mg twice daily, ≥12 years: 500 mg twice daily) are options Standard and contact precautions should be used for the incontinent child Cryptosporidium Cryptosporidiosis is caused by C parvum and C hominis, protozoal species spread by fecal–oral transmission Humans, cattle, and other animals are reservoir species In the United States, almost 8,000 cases occur annually, so a travel history is not a prerequisite for infection Risk factors include swallowing contaminated water (including at hotel swimming pools), hiking and drinking unfiltered water, daycare attendees, workers, and the families of children who attend day care, and travelers Asymptomatic infection can be seen Most patients will develop low-grade fever, watery, nonbloody diarrhea with crampy abdominal pain, vomiting, and weight loss Symptoms last to weeks, although more severe and chronic symptoms can be seen in HIV-infected patients and other immunocompromised hosts In addition, immunocompromised children can develop extraintestinal manifestations: biliary tract and pneumonitis DFA and EIAs are more sensitive than detection of oocytes in stool Self-limited illness in immunocompetent hosts usually does not require treatment Nitazoxanide is approved for children year of age and older (3-day course for children year of age and older: to years: 100 mg twice daily, to 11 years: 200 mg twice daily, ≥12 years: 500 mg twice daily) Longer treatment courses may be needed in HIV-infected children and other immunocompromised hosts Standard and contact precautions should be used for the incontinent child Gram-negative Enterics: Vibrio, E coli, Campylobacter, Shigella Several gram-negative enteric pathogens are more common in developing nations than in industrialized countries These include Vibrio cholera, enterotoxigenic, enteropathic, enteroinvasive, and enteroaggregative E coli, and Campylobacter ( e-Table 94.22 ) Cholera is characterized by painless watery diarrhea, and persons most at risk are those with low gastric acidity It can be easily spread in congregate settings, and is a major cause of diarrhea in camps for displaced persons The character of diarrhea varies based on E coli type, and some types produce a Shiga-like toxin Campylobacter is also a cause of dysentery (bloody stools with fecal leukocytes) in the United States, but is more common internationally The most at-risk group for Shigella domestically is the child in daycare In addition to the acute symptoms (which are more severe in immunocompromised hosts), patients with Campylobacter can also have postinfectious sequelae with Guillain–Barré syndrome, including the Miller Fisher variant (ataxia out of proportion to sensory loss, areflexia, and ophthalmoplegia) All three pathogens can be cultured on routine stool culture media The mainstay of therapy is rehydration Adjunctive antibiotic treatment is recommended to decrease symptom duration, decrease fecal shedding, and decrease secondary transmission Standard and contact precautions are recommended Schistosomiasis Schistosomiasis is caused by mammalian blood trematodes (flukes) in the Schistosoma genus Freshwater snails transmit the infection through penetration of intact skin Schistosomiasis is endemic in more than 75 countries worldwide including in Africa, the Middle East, China, Southeast Asia, Brazil, Venezuela, and the Caribbean Adult worms can live as long as 30 years, causing disease decades after patients have left an endemic area The clinical manifestations of the most common syndromes caused by schistosomes are summarized in eTable 94.23 The severity of chronic illness is associated with worm burden Those with low to moderate burden may never develop significant illness, while those with significant worm burden may develop mucoid bloody diarrhea and tender hepatomegaly Severe infection with the intestinal form of the disease may result in development of portal hypertension, ascites, esophageal varices, and hematemesis The drug of choice is praziquantel (dosing varies depending on the species) and the treatment must be repeated approximately to months later due to failure of the medication to kill developing worms Schistosomal dermatitis (swimmer’s itch) does not require therapy Paradoxical inflammation after antiparasitic therapy is common and can be treated with systemic corticosteroids Standard precautions exist for isolation of infected patients Soil Helminthic Infections A number of helminthic infections cause human disease Most are transmitted through the fecal–oral route, though in some cases helminths can penetrate intact skin The most common helminthic infections are Enterobius vermicularis (pinworms), Trichuris trichiura (whipworm), Ascaris lumbricoides (roundworm), Ancylostoma (hookworm), cutaneous larva migrans (CLM) (sandworm), and Strongyloides Most infected individuals are asymptomatic Clinical manifestations are strongly related to the intensity of the infection and worm burden Some infections result in anemia or impaired growth and cognition Diagnosis is usually made via visualization of larvae in the stool The clinical manifestations, diagnosis, and treatment are summarized in e-Table 94.24 Most can be treated with either albendazole or mebendazole; albendazole is typically more tolerable for patients in terms of taste and side effects The albendazole dose is 400 mg for both children and adults A single-dose regimen is the recommended treatment for Ancylostoma, Ascaris, and Enterobius, whereas Trichuris requires a 3-day course and Strongyloides a 7-day course with twice-daily dosing SKIN/SOFT TISSUE INFECTIONS Dermatologic conditions are common among persons who have recently traveled ( Table 94.21 ) Urticaria is common, and can be caused by Strongyloides stercoralis, scabies, schistosomiasis, onchocerciasis, or insect bites Insect bites (such as bedbugs and fleas) are the most common cutaneous finding in the returning traveler The most common cause of ulcers is pyoderma, caused by streptococci and staphylococci, but can also be caused by cutaneous leishmaniasis Eschars may be seen in rickettsial disorders such as Mediterranean spotted fever, scrub typhus, and African tick typhus Burrowing lesions can be caused by botflies (myiasis) and fleas (tungiasis) Leishmaniasis