TABLE IV-114 Risk Factors for Active Tuberculosis Among Persons Who Have Been Infected With Tubercle Bacilli 6 page

multidrug-resistant malaria.

IV-222. The answer is E. (Chap. 210) Thick and thin smears are a critical part of the evaluation of fever in a person with recent time spent in a Plasmodium-endemic region. Thick smears take a longer time to process but increase sensitivity in the setting of low parasitemia. Thin smears are more likely to allow for precise morphologic evaluation to differentiate among the four different types of Plasmodium infection and to allow for prognostic calculation of parasitemia. If clinical suspicion is high, repeat smears should be performed if the results are initially negative. If personnel are not available to rapidly interpret a smear, empirical therapy should be strongly considered to ward off the most severe manifestation of Plasmodium falciparum infection. Antibody-based diagnostic tests that are sensitive and specific for P. falciparum infection have been introduced. The results will remain positive for weeks after infection and do not allow quantification of parasitemia.

IV-223. The answer is C. (Chap. 211) The patient is seen in an endemic area for Babesia microti, which includes Nantucket, Martha’s Vineyard, Block Island, Shelter Island, Long Island, southeastern coastal Massachusetts, Connecticut, and Rhode Island. Her flulike symptoms and tick bite make this disease very likely. Patients generally present with these symptoms or occasionally neck stiffness, sore, throat abdominal pain, and weight loss. Physical examination findings are typically normal with the exception of fever. The presence of erythema chronicum migrans suggests concurrent Lyme disease because a rash is not a feature of babesiosis. Although thick or thin preparation typically demonstrates the ring form of this protozoan, if these are negative, the 18S rRNA may be demonstrated by polymerase chain reaction. The ring forms are distinguished from Plasmodium falciparum by the absence of central brownish deposit seen in malarial disease. Babesia duncani is typically found on the West Coast of the United States, and Babesia divergens have been reported sporadically in Washington state, Missouri, and Kentucky. Therapy for severe Babesia microti disease in adults is clindamycin with additional quinine. Red blood cell exchange transfusion may be considered for B. microti but is not recommended as it is with B. divergens.

IV-224. The answer is C. (Chap. 212) Most cases of leishmaniasis occur on the Indian subcontinent and Sudan. The most commonly used technique for diagnosis of visceral leishmaniasis (kala azar) is a rapid immunochromatographic test for recombinant antigen rK39 from Leishmania infantum. This is widely available, rapid, and safe, requiring only a fingerprick of blood with results available in approximately 15 minutes. Although splenic aspiration with demonstration of amastigotes in tissue smear is the gold standard for the diagnosis of visceral leishmaniasis and culture may increase the sensitivity, the test is invasive and may be dangerous in inexperienced hands. Polymerase chain reaction for the leishmaniasis nucleic acid is only available at specialized laboratories and is not routinely used clinically. Leishmaniasis is not diagnosed via stool analysis.

IV-225. The answer is C. (Chap. 213) Trypanosoma cruzi is the causative agent of Chagas disease or American trypanosomiasis, which only occurs in the Americas. The protozoa is transmitted to mammalian hosts by the reduviid bugs, which become infected by sucking blood from animals or humans with circulating protozoa. The infective form of T. cruzi is excreted in the feces and infects humans through contact with breaks in the skin, mucous membranes, or conjunctiva. Infection has also been transmitted from blood transfusion, organ transplant, and ingestion of contaminated food or drink. Acute Chagas disease is typically a mild febrile illness followed by a chronic phase characterized by subpatent parasitemia, antibodies to T. cruzi, and no symptoms. About 10% to 30% of patients with

chronic Chagas disease develop symptoms, usually related to cardiac or gastrointestinal lesions. Deer flies are the transmission vector of Loa loa (filariasis).

IV-226. The answer is D. (Chap. 213) This patient most likely has chronic Chagas disease with cardiac involvement and biventricular systolic dysfunction. Chagas disease is a health problem in rural Mexico, Central America, and South America. Most acute cases occur in children, but the epidemiology is uncertain because most cases go undiagnosed. The heart is the organ most often involved in chronic Chagas disease with biventricular systolic dysfunction and conduction abnormalities [right bundle branch block and left anterior hemiblock (LAH)]. Apical aneurysms and mural thrombi may occur. Chronic Chagas disease is diagnosed by demonstration of specific immunoglobulin G antibodies to Trypanosoma cruzi antigens. False-positive results may occur in patients with other parasitic infections or autoimmune disease. The World Health Organization recommends a positive test be confirmed with a separate assay. Polymerase chain reaction (PCR) to detect T. cruzi DNA in chronically infected patients has not been shown to be superior to serology, and no commercially available PCR tests are available. Given the patient’s demographics, lack of coronary artery disease risk factors, and indolent symptoms, acute myocardial infarction, ischemic cardiomyopathy, and hypertensive cardiomyopathy are less likely diagnoses. Right heart catheterization with placement of a Swan-Ganz catheter could quantify left and right heart pressures and cardiac output. Constrictive pericarditis could also be evaluated, but this diagnosis is less likely with the presence of signs of left heart failure.

IV-227. The answer is A. (Chap. 213) Current consensus is that all Trypanosoma cruzi–infected patients up to 18 years old and all newly infected adults be treated for acute Chagas disease. Unfortunately, the only available drugs, benznidazole and nifurtimox, lack efficacy and have notable side effects. In acute Chagas disease, nifurtimox reduces the duration of symptoms and parasitemia and decreases the acute mortality Rate. However, only approximately 70% of acute infections are cured by a full course of treatment. Benznidazole is at least as effective as nifurtimox and is generally the treatment of choice in Latin America. The role of therapy in patient with indeterminate or chronic asymptomatic Chagas disease is controversial. Some experts recommend that therapy be offered. In contrast, randomized studies have shown benefit of treatment in children. The current antifungal azoles, including voriconazole, do not have adequate efficacy against T. cruzi, although newer agents in this class show promise in animal studies. Serologic confirmation with T. cruzi immunoglobulin G testing is used to diagnose chronic, not acute, Chagas disease. Malaria is endemic to Honduras below 1000 m elevation, and primaquine is effective therapy in those cases. Thin and thick smears evaluated by experts should not confuse Plasmodium spp. with T. cruzi.

IV-228. The answer is A. (Chap. 213) Human African trypanosomiasis (HAT) or sleeping sickness is caused by the protozoan Trypanosoma brucei complex. HAT remains a major public health problem in Africa despite its near-eradication in the 1960s. Although HAT only occurs in sub-Saharan Africa, it is important to distinguish between the West African ( T.b. gambiense) and East African (T.b. rhodesiense) forms. Tsetse flies are the transmission vector for both forms. Humans are the major reservoir of West African trypanosomiasis, and it occurs in rural areas, rarely affecting tourists. Antelope and cattle are the reservoirs for T.b. rhodesiense, and infection has been reported in safari tourists. A primary lesion (trypanosomal chancre) typically appears 1 week after the bite of an infected tsetse fly. This is followed by a systemic illness with fever and lymphadenopathy (stage 1 disease). Myocarditis may occur, which can be fatal. Central nervous system (CNS) involvement follows (stage

2 disease) with cerebrospinal fluid (CSF) pleocytosis, elevated protein, and elevated pressure. During this stage, trypanosomes may be found in CSF. T.b. rhodesiense tends to be more aggressive with CNS disease developing earlier than T.b. gambiense. Symptoms during stage 2 disease include progressive somnolence and indifference sometimes alternating with insomnia and nighttime restlessness. If untreated, symptoms progress to coma and death. Diagnosis requires demonstration of the protozoa from blood, CSF, lymph node material, bone marrow, or chancre fluid. There are serologic tests for T.b. gambiense, but they lack the sensitivity or specificity for treatment decisions. There are not yet commercially available polymerase chain reaction tests. All patients with HAT should have a lumbar puncture to evaluate for CNS involvement, which will determine therapy. Suramin is effective for stage 1 East African HAT ( T.b. rhodesiense). Pentamidine is first-line treatment for stage 1 West African HAT. When the CSF is involved, eflornithine is used for West African HAT and melarsoprol for East African HAT. Melarsoprol is an arsenical that is highly toxic, with a risk of encephalopathy.

IV-229. The answer is C. (Chap. 214) The magnetic resonance imaging (MRI) scan shows the classic lesions of encephalitis caused by Toxoplasma gondii in a patient with advanced immunosuppression caused by HIV infection. Cats are the definitive host for the sexual phase of Toxoplasma, and oocysts are shed in their feces. In the United States, up to 30% of 19-year-old young adults and up to 67% of adults older than 50 years of age have serologic evidence of Toxoplasma exposure. Patients with HIV infection are at risk of reactivation of latent toxoplasmosis with resultant encephalitis when the CD4 T-cell count falls below 100/μL. Patients receiving immunosuppressive medication for lymphoproliferative disease or solid organ transplant are also at risk for reactivation of latent disease. Although the central nervous system (CNS) is the most common site of symptomatic reactivation disease, the lymph nodes, lung, heart, eyes, and gastrointestinal tract may be involved. Toxoplasma usually causes encephalitis, not meningitis; therefore, cerebrospinal fluid (CSF) findings may be unremarkable or have modest elevations of cell count and protein (with normal glucose). The treatment of choice for CNS toxoplasmosis is pyrimethamine plus sulfadiazine. Trimethoprim–sulfamethoxazole is an acceptable alternative. The differential diagnosis of encephalitis in patients with AIDS includes lymphoma, metastatic tumor, brain abscess, progressive multifocal leukoencephalopathy, fungal infection, and mycobacterial infection. In this case, given the classic MRI findings, toxoplasmosis is most likely.

IV-230. The answer is C. (Chap. 215) Of the listed protozoa, only Giardia infection can be diagnosed with stool ova and parasite examination. Stool antigen immunoassay can be used to diagnose Giardia and Cryptosporidium spp. Fecal acid-fast testing may be used to diagnose Cryptosporidium, Isospora, and Cyclospora spp. Microsporidia require special fecal stains or tissue biopsy for diagnosis.

IV-231. The answer is D. (Chap. 215) Trichomoniasis is transmitted via sexual contact with an infected partner. Many men are asymptomatic but may have symptoms of urethritis, epididymitis, or prostatitis. Most women have symptoms of infection that include vaginal itching, dyspareunia, and malodorous discharge. These symptoms do not distinguish Trichomonas infection from other forms of vaginitis, such as bacterial vaginosis. Trichomoniasis is not a self-limited infection and should be treated for symptomatic and public health reasons. Wet-mount examination for motile trichomonads has a sensitivity of 50% to 60% in routine examination. Direct immunofluorescent antibody staining of secretions is more sensitive and can also be performed immediately. Culture is not widely available and takes 3 to 7 days. Treatment should consist of metronidazole either as a single 2-g dose or 500-mg

doses twice daily for 7 days; all sexual partners should be treated. Trichomoniasis resistant to metronidazole has been reported and is managed with increased doses of metronidazole or with tinidazole.

ГУ-232. The answer is E.(Chap. 215) Giardiasis is diagnosed by detection of parasite antigens in the feces or by visualizing cysts or trophozoites in feces or small intestine. There is no reliable serum test for this disease. Because a wide variety of pathogens are responsible for diarrheal illness, some degree of diagnostic testing beyond the history and physical examination is required for definitive diagnosis. Colonoscopy does not have a role in diagnosing Giardia infection. Giardiasis can persist in symptomatic patients and should be treated. Severe symptoms such as malabsorption, weight loss, growth retardation, and dehydration may occur in prolonged cases. Additionally, extraintestinal manifestations such as urticarial, anterior uveitis, and arthritis have been associated with potential giardiasis. A single oral 2-g dose of tinidazole is reportedly more effective than a 5-day course of metronidazole with cure rates above 90% for both. Paromomycin, an oral poorly absorbed aminoglycoside, can be used for symptomatic patients during pregnancy, but its efficacy for eradicating infection is not known. Clindamycin and albendazole do not have a role in treatment of giardiasis. Refractory disease with persistent infection can be treated with a longer duration of metronidazole.

ГУ-233. The answer is D.(Chap. 215) Cryptosporidium typically causes a self-limited diarrheal illness in immunocompetent patients but may cause severe debilitating disease in patients with severe immunodeficiency, such as advanced HIV infection. Outbreaks in immunocompetent hosts are caused by ingestion of oocysts. Infectious oocysts are excreted in human feces, causing human-to-human transmission. Waterborne transmission of oocysts accounts for disease in travelers and common-source outbreaks. Oocysts resist killing by routine chlorination of drinking and recreational water sources. Infection may be asymptomatic in immunocompetent and immunosuppressed hosts. Diarrhea is typically watery and nonbloody and may be associated with abdominal pain, nausea, fever, and anorexia. In immunocompetent hosts, symptoms usually subside in 1 to 2 weeks without therapy. In advanced AIDS with CD4 counts below 100/uL, severe symptoms may develop, leading to significant electrolyte and volume loss. Nitazoxanide is approved for treatment of Cryptosporidium but to date has not been shown to be effective in HIV-infected patients. The best available therapy for these patients is antiretroviral therapy to reduce immune suppression. Tinidazole and metronidazole are used to treat giardiasis and trichomoniasis, not cryptosporidiosis.

ГУ-234. The answer is D.(Chap. 216) There are roughly 12 cases of trichinellosis reported each year in the United States. Because most infections are asymptomatic, this may be an underestimate. Recent outbreaks in North American have been related to ingestion of wild game, particularly bear. Heavy infections can cause enteritis; periorbital edema; myositis; and, infrequently, death. This infection, caused by ingesting Trichinella cysts, occurs when infected meat from pigs or other carnivorous animals is eaten. Laws that prevent feeding pigs uncooked garbage have been an important public health measure in reducing Trichinella infection in this country. Person-to-person spread has not been described. The majority of infections are mild and resolve spontaneously.

ГУ-235. The answer is E.(Chap. 216) Trichinellosis occurs when infected meat products are eaten, most frequently pork. The organism can also be transmitted through the ingestion of meat from dogs, horses, and bears. Recent outbreaks in the United States and Canada have been related to consumption of wild game, particularly bear meat. During the first week of infection, diarrhea, nausea, and vomiting

are prominent features. As the parasites migrate from the gastrointestinal (GI) tract, fever and eosinophilia are often present. Larvae encyst after 2 to 3 weeks in muscle tissue, leading to myositis and weakness. Myocarditis and maculopapular rash are less common features of this illness. In pork, larvae are killed by cooking until the meat is no longer pink or by freezing at -15°C for 3 weeks. However, arctic Trichinella nativa larvae in walrus or bear meat are resistant to freezing. Giardia and Campylobacter are organisms that are frequently acquired by drinking contaminated water; neither produces this pattern of disease. Although both cause GI symptoms (and Campylobacter causes fever), neither causes eosinophilia or myositis. Taenia solium, or pork tapeworm, shares a similar pathogenesis to Trichinella spp. but does not cause myositis. Cytomegalovirus has varied presentations but none that lead to this presentation.

IV-236 and IV-237. The answers are D and B, respectively.(Chap. 216) Visceral larva mi grans, caused in this case by the canine roundworm Toxocara canis, most commonly affects young children who are exposed to canine stool. Toxocara eggs are ingested and begin their life cycle in the small intestine. They migrate to many tissues in the body. Particularly characteristic of this illness are hepatosplenomegaly and profound eosinophilia, at times close to 90% of the total white blood cell count. Staphylococci will not typically cause eosinophilia. Trichinellosis, caused by ingesting meat from carnivorous animals that has been infected with Trichinella cysts, does not cause hepatosplenomegaly and is uncommon without eating a suspicious meal. Giardiasis is characterized by profuse diarrhea and abdominal pain without systemic features or eosinophilia. Cysticercosis typically causes myalgias and can spread to the brain, where it is often asymptomatic but can lead to seizures. The vast majority of Toxocara infections are self-limited and resolve without therapy. Rarely, severe symptoms may develop with deaths caused by central nervous system, myocardial, or respiratory disease. Severe myocardial involvement manifests as acute myocarditis. In these patients, glucocorticoids are administered to reduce the inflammatory complications. Antihelminthic drugs such as albendazole, mebendazole, or praziquantel have not been shown conclusively to alter the course of visceral larval migrans. Metronidazole is used for infections caused by Trichomonas, not tissue nematodes.

ГУ-238. The answer is A.(Chap. 216) Angiostrongylus cantonensis, the rat lungworm, is the most common cause of human eosinophilic meningitis. The infection principally occurs in Southeast Asia and the Pacific Basin, although cases have also been described in Cuba, Australia, Japan, and China. Infective larvae are excreted in rat feces and ingested by land snails and slugs. Humans acquire infection by ingesting the mollusks, vegetables contaminated by mollusk slime, or seafood (crabs, freshwater shrimp) that consumed the mollusks. The larvae migrate to the brain, where they initiate a marked eosinophilic inflammatory response with hemorrhage. Clinical symptoms develop 2 to 35 days after ingestion of larvae, and the initial presentation typically includes headache (indolent or acute), fever, nausea, vomiting, and meningismus. The cerebrospinal fluid (CSF) findings are as in this case with an eosinophil percentage greater than 20%. A. cantonensis larvae are only rarely demonstrated in the CSF. The diagnosis usually relies on the presence of eosinophilic meningitis and compatible epidemiology. There is no specific chemotherapy for A. cantonensis meningitis. Supportive care includes repeat removal of CSF to control intracranial pressure. Glucocorticoids may reduce inflammation. In most cases, cerebral angiostrongyliasis has a self-limited course with complete recovery. Gnathostoma spinigerum is a less common cause of eosinophilic meningoencephalitis. It also causes migratory cutaneous swellings or eye infections. It is also endemic in Southeast Asia and

China and is usually transmitted by eating undercooked fish or poultry (som fak in Thailand and sashimi in Japan). Trichinella murrelli and Trichinella nativa cause trichinosis in North America and the Arctic, respectively. Trichinella cara is the cause of larval migrans.

IV-239. The answer is B.(Chap. 217) Strongyloides is the only helminth that can replicate in the human host, allowing autoinfection. Humans acquire Strongyloides when larvae in fecally contaminated soil penetrate the skin or mucous membranes. The larvae migrate to the lungs via the bloodstream; break through the alveolar spaces; ascend the respiratory airways; and are swallowed to reach the small intestine, where they mature into adult worms. Adult worms may penetrate the mucosa of the small intestine. Strongyloides is endemic in Southeast Asia, sub-Saharan Africa, Brazil, and the Southern United States. Many patients with Strongyloides are asymptomatic or have mild gastrointestinal symptoms or the characteristic cutaneous eruption, larval currens, as described in this case. Small bowel obstruction may occur with early heavy infection. Eosinophilia is common with all clinical manifestations. In patients with impaired immunity, particularly glucocorticoid therapy, hyperinfection or dissemination may occur. This may lead to colitis, enteritis, meningitis, peritonitis, and acute renal failure. Bacteremia or gram-negative sepsis may develop because of bacterial translocation through disrupted enteric mucosa. Because of the risk of hyperinfection, all patients with Strongyloides infection, even asymptomatic carriers, should be treated with ivermectin, which is more effective than albendazole. Fluconazole is used to treat candidal infections. Mebendazole is used to treat trichuriasis, enterobiasis (pinworm), ascariasis, and hookworm. Mefloquine is used for malaria prophylaxis.

ГУ-240. The answer is B.(Chap. 217) Ascaris lumbricoides is the longest nematode (15-40 cm) parasite of humans. It resides in tropical and subtropical regions. In the United States, it is found mostly in the rural Southeast. Transmission is through fecally contaminated soil. Most commonly, the worm burden is low, and it causes no symptoms. Clinical disease is related to larval migration to the lungs or to adult worms in the gastrointestinal tract. The most common complications occur because of a high gastrointestinal adult worm burden, leading to small bowel obstruction (most often in children with a narrow-caliber small bowel lumen) or migration leading to obstructive complications such as cholangitis, pancreatitis, or appendicitis. Rarely, adult worms can migrate to the esophagus and be orally expelled. During the lung phase of larval migration (9-12 days after egg ingestion), patients may develop a nonproductive cough, fever, eosinophilia, and pleuritic chest pain. Eosinophilic pneumonia syndrome (Loftier's syndrome) is characterized by symptoms and lung infiltrates. Meningitis is not a known complication of ascariasis but can occur with disseminated strongyloidiasis in an immunocompromised host.

ГУ-241. The answer is A.(Chap. 217) Ascariasis should always be treated, even in asymptomatic cases, to prevent serious intestinal complications. Albendazole, mebendazole, and ivermectin are effective. These agents should not be administered to pregnant women. Pyrantel is safe in pregnancy. Metronidazole is used for anaerobic bacterial and Trichomonas infections. Fluconazole is mostly used to treat Candida infections. Diethyl-carbamazine (DEC) is first-line therapy for active lymphatic filariasis. Vancomycin has no effect onnematodes.

IV-242. The answer is E.(Chap. 217) This patient's most likely diagnosis is anisakiasis. This is a nematode infection in which humans are an accidental host. It occurs hours to days after ingesting eggs that previously settled into the muscles of fish. The main risk factor for infection is eating raw fish. Presentation mimics an acute abdomen. History is critical because upper endoscopy is both diagnostic

and curative. The implicated nematodes burrow into the mucosa of the stomach, causing intense pain, and must be manually removed by endoscope or, on rare occasion, surgery. There is no medical agent known to cure anisakiasis.

ГУ-243. The answer is E.(Chap. 218) This patient likely has filariasis with acute lymphadenitis caused b у Wuchereria bancrofti. It is endemic throughout the tropics and subtropics, including Asia, the Pacific Islands, Africa, parts of South America, and the Caribbean. W. bancrofti is the most widely distributed human filarial parasite and is transmitted by infected mosquitoes. Lymphatic infection is common and may be acute or chronic. Chronic lower extremity lymphatic infection causes elephantiasis. Definitive diagnosis requires demonstration of the parasite. Microfilariae maybe found in blood, hydrocele, or other body fluid collections by direct microscopic examination. Enzyme-linked immunosorbent assays for circulating antigens are available commercially and have sensitivity of greater than 93% with excellent specificity. Polymerase chain reaction-based assays have been developed that may be as effective. In cases of acute lymphadenitis, ultrasound examination with Doppler may actually reveal motile worms in dilated lymphatics. Live worms have a distinctive movement pattern (filarial dance sign). Worms may be visualized in the spermatic cords of up to 80% of men infected with W. bancrofti. Stool ova and parasite examination is not useful for demonstration of W. bancrofti.

ГУ-244. The answer is B.(Chap. 218) Diethylcarbamazine (DEC), which has macro- and microfilaricidal properties, is the first-line treatment for acute filarial lymphadenitis. Albendazole, doxycycline, and ivermectin are also used to treat microfilarial infections (not macrofilarial). There is growing consensus that virtually all patients with Wuchereria bancrofti infection should be treated, even if asymptomatic, to prevent lymphatic damage. Many of these patients have microfilarial infection with subclinical hematuria, proteinuria, and so on. Albendazole and doxycycline have demonstrated macrofilaricidal efficacy. Combinations of DEC with albendazole, ivermectin, and doxycycline have efficacy in eradication programs. The World Health Organization established a global program to eliminate lymphatic filariasis in 1997 using a single annual dose of DEC plus either albendazole (non-African regions) or ivermectin (Africa). Praziquantel is used for treatment of schistosomiasis.

ГУ-245. The answer is B.(Chap. 218) This patient has loiasis caused by the African eye worm Loa loa. It is endemic to the rain forests of Central and West Africa. Microfilaria circulate periodically in blood with macrofilaria living in subcutaneous tissues including the subconjunctiva. Loiasis is often asymptomatic in indigenous regions with recognition, as in this case, only with visualized macrofilarial migration. Angioedema and swelling may occur in affected areas. Diethylcarbamazine (DEC) is effective treatment for the macrofilarial and microfilarial stages of disease. Multiple courses may be necessary. Albendazole and ivermectin are effective in reducing microfilarial loads but are not approved by the U.S. Food and Drug Administration. There are reports of deaths in patients with heavy loads of microfilaria receiving ivermectin. Terbinafine is the treatment for ringworm, Voriconazole is an antifungal with no activity against worms.

ГУ-246. The answer is A.(Chap. 219) Human schistosomiasis is caused by five species of parasitic trematodes. Whereas Schistosoma mansoni, Schistosoma japonicum, Schistosoma mekongi, and Schistosoma intercalatum are intestinal species, Schistosoma haematobium is a uni-nary species. There are reportedly up to 300 million individuals infected with Schistosoma. Figure IV-246 shows the

global distribution. S. haematobium is not seen in South America. All forms of schistosomiasis are initiated by penetration of infective cercariae released from infected snails into fresh water. After entering the skin, the schistosome migrates via venous or lymphatic vessels to either the intestinal or urinary venous system, depending on the species. Acute skin infection causes dermatitis (swimmer's itch) within 2 to 3 days. Katayama fever, acute schistosomal serum sickness-related to migration, may develop in 4 to 8 weeks. Eosinophilia is common in acute infection. This has become a more common global health problem because travelers are exposed while swimming or boating in infected fresh water bodies. Chronic schistosomiasis depends on the species and the location of infection. The intestinal species are responsible for portal hypertension. S. haematobium causes urinary symptoms and a higher risk of urinary tract carcinoma. Immunologic tests are available to diagnose schistosomiasis, and in some cases, stool or urine examination results may be positive.

Date: 2016-04-22; view: 766