Repeated Stool Examinations Research Articles

What was the main factor in successful control of ascariasis in Korea?

In the l950s, under the legacy of traditional agriculture, Ascaris lumbricoides, spread epidemically in the war-bitten society of Korea. Consensus on the parasite control was drafted in the Parasite Disease Prevention Act, which passed a parliamentary agreement in 1966, and established safe disposal of feces and mass chemotherapy as control strategies. Biannual stool examinations and treating infected schoolchildren were basic scheme of the control activity through which revenue could be secured for organized business. In the 27 years following 1969, a maximum of 16 million stool examinations had been done every year. Cellophane thick smear enabled the task. The infection declined remarkably in the 1970s when industrialization and green revolution proceeded. A population study of A. lumbricoides in the late 1970s helped us better understand its epidemiology. The data also settled down the understandable protest of teachers against the repeated stool examinations. In the 9 years following 1987, the target population was gradually reduced when the egg positive rate was below 0.1%. An article in the Korean Law, stipulating obligatory stool examinations, was made optional. Although the long-term Korean effort of Ascaris control was a success, the effect of mass chemotherapy was not as succinct in terms of lowering reinfection. In the period of control, Korean agricultural technology changed, and the economy grew and supplied sanitary facilities by which the vicious cycle was disconnected. Reduction of morbidity was a benefit of mass chemotherapy, which is the only control method feasible in economically difficult countries. The most important hurdle of parasite control in the 1960s was poverty of general population and limited financial resources in Korea but the society formed a consensus on the priority of intestinal helminthiasis control during the ordeal period. The national consensus in the 1960s was the critical milestone for Ascaris control in Korea. Under the social agreement, application of timely technical and research advancements in parasitology achieved the success of ascariasis elimination. The successful experience of ascariasis elimination in Korea can be a benchmark for countries where neglected tropical diseases are endemically recycled.

Diarrhea associated with Pentatrichomonas hominis in an infant

Pentatrichomonas hominis is a flagellated protozoan parasite that resides in the digestive tract of humans and is generally nonpathogenic. Although parasites of diarrheal etiology are widespread, neonatal infection with P. hominis is an uncommon incident. This case report depicts an instance of active P. hominis in an 8-month-old child with complaints of fever, vomiting, and loose stools. Stool examination was done with saline and iodine wet mount that showed motile trophozoites of P. hominis with a jerky movement. Treatment with metronidazole was effective as no parasite was found on repeated stool examinations. Pentatrichomonas hominis should be recognized as a cause of diarrhea in neonates, despite being rare.

Acidic mammalian chitinase tuning after enteric helminths eradication in inflammatory respiratory disease patients.

This study aimed at investigating the presence of intestinal parasitic infections in inflammatory respiratory diseases patients during the disease attack, and measuring the acidic mammalian chitinase (AMCase) gene expression in blood before and after infection eradication. This case-control study included 123 inflammatory respiratory diseases patients and 120 apparently healthy individuals. Repeated stool examination was done, while total and specific IgE were measured. AMCase gene expression was analysed by real time-polymerase chain reaction (RT-PCR). Infection was detected in 32.5% of the diseased and 23.25% of the healthy individuals. Higher rate of the helminthic infection was detected (23.57) in comparison to the protozoal (12.19%) in the patients. A significantly higher rate of infection with the chitin-rich helminths "Enterobius vermicularis & Hymenolepis nana" and level of anti-Dermatophagoide-IgE were reported in the patients (14.63%, 6.5% and 23.57%, respectively). AMCase expression was significantly higher in helminths-infected patients than the noninfected, or protozoa infected. After infection eradication, AMCase expression significantly declined in the previously helminth-infected patients (mean ± SD=13.9±3.918 before and 4.515±1.93 after), but insignificantly affected in the protozoa infected (mean ± SD=2.095±.285 before and 2.675±1.181 after). Chitin-rich intestinal helminths are suspected to precipitate Th2-immune response in remote tissues by enhancing systemic AMCase expression through intestinal mucosa and macrophages irritation.

Answer to March 2017 Photo Quiz

Answer: Disseminated strongyloidiasis presenting with larva migrans or cutaneous strongyloidiasis. A repeated stool examination for ova and parasites revealed a few typical rhabditiform larvae (not shown); examination of a fresh sputum smear revealed no larvae. On hospital day 6, the patient

Strongyloides hyperinfection presenting as proteinlosing enteropathy

Abstract Strongyloides stercoralis, a soil-transmitted helminth, affects many people in tropical and subtropical countries. It is known to cause asymptomatic infection in immunocompetent and hyperinfection and disseminated Strongyloides infection in immunocompromised due to autoinfection. Here, we report a case of Strongyloides hyperinfection presenting with proteinlosing enteropathy. The diagnosis was made only with duodenal biopsy as the repeated stool examinations were negative. He was treated with ivermectin and his condition improved.

Four Thai Patients With Chronic Diarrhea, Malabsorption, and Weight Loss

Diagnosis: Capillariasis associated with tubular narrowing of multiple small-bowel loops with fold effacement. The clinical and radiographic presentations of these cases are representative of Capillaria philippinensis infection. Infection with C. philippinensis is primarily acquired by ingestion of raw, undercooked, small, fresh- or brackish-water fish [1]. Capillaria philippinensis, first discovered in the Philippines, has subsequently been detected in Thailand, Japan, Iran, Egypt, and Taiwan, with major outbreaks reported in Thailand and the Philippines [2]. Typically, patients present with signs and symptoms of malabsorption inclusive of chronic diarrhea, edema, muscle wasting, and abdominal pain; laboratory data reveal low serum albumin and potassium [3–4]. The diagnosis of C. philippinensis is usually based on the detection of eggs (Figure 1), larva, and/or adult worms with or without egg in stool specimens (Figure 1), although excretion can be sporadic, necessitating multiple repeated stool examinations, with small intestinal aspiration or biopsy to confirm the diagnosis in some cases [1–2]. Notably, mortality has been reported in patients with C. philippinensis who did not have capillaria eggs or larva recovered from stool specimens [2–3]. The detection of the parasite’s stichosome (the posterior glandular esophagus) and stichocytes (large glandular cells) by hematoxylin and eosin stain are not diagnostic, as these can also be identified in biopsies of patients with Trichinella spiralis and Trichuris trichiura infection. The clinical presentations and locations of lesions can readily help in the differentiation and case detection of these 3 parasitic infections [5]. Whereas patients with C. philippinensis typically present with clinical manifestations of chronic watery diarrhea and malabsorption, those with T. trichiura usually present with prolonged diarrhea, blood-streaked stool, anemia, colitis, proctitis, and rectal prolapse (in patients with heavy infestation). Cases with T. spiralis usually have biphasic presentations that begin with clinical manifestations of nausea, vomiting, and diarrhea (intestinal phase) followed by intense myalgias and periorbital edema (muscular phase) [5]. Additionally, C. philippinensis typically involves the distal jejunum and proximal ileum, T. trichiura tends to cause lesions limited to the large bowel, and T. spiralis is typically associated with encysted larva that migrated to specific organ tissues (eg, muscle, myocardium, and brain). In each of our 4 reported cases, the initial stool specimen was negative for C. philippinensis. Subsequent stool specimens were positive for C. philippinensis in 2 patients, and all 4 had small-bowel biopsies remarkable for severe villous blunting, inflammatory cell infiltration, and visualization of nematodes in longitudinal sections with the identification of stichocytes

Hookworm infestation, an old but not vanished disease

Hookworms, together with other helminthes infestations, were serious health problems in Taiwan before. With improvements in public health and medicine, the prevalence of parasite infestations drops significantly and current attention has been shifted to foreign laborers coming from the Southeast Asia. Herein we reported a case of hookworm infestation who presented as subacute diarrhea. Initially, only peripheral eosinophilia was revealed. Anti-helminth treatment, but not the immunosuppressant for eosinophilic gastroenteritis, was given when the hookworm ova were finally harvested after repeated stool examinations. Please remember the old diseases when you meet a patient with gastrointestinal complaints and peripheral eosinophilia, especially when there are intermittent skin atopic manifestations. Repeated parasite ova checks with concentration method are necessary in acute stage, especially when the worm burden is not heavy.

Intestinal schistosomiasis caused by both Schistosoma intercalatum and Schistosoma mansoni

A case is presented of intestinal schistosomiasis due to both Schistosoma intercalatum and Schistosoma mansoni in a 30-year-old man from Senegal with discussion of diagnostic approach, species identification and determination of the effect of treatment. The patient was admitted to hospital for investigation of renal failure, arterial hypertension and hypereosinophilia. Repeated stool examinations for ova and parasites were negative. Ultrasonography (US) and computed tomography (CT) of the abdomen showed no abnormalities. US of the urinary tract showed kidneys of borderline size with increased echogenicity. Cystoscopy and histopathological examination of bladder biopsy specimens were normal. Flexible colonoscopy revealed numerous nodular lesions in the rectosigmoid region and a few similar lesions in the transverse colon, the histopathological examination of which showed deposition of Schistosoma ova with granuloma formation. Examination of multiple crush biopsy specimens from the rectosigmoid region revealed numerous granulomas formed around Schistosoma eggs which had a terminal spine and were identified as S. intercalatum (longer than Schistosoma haematobium and with a slightly curved terminal spine) and a very few S. mansoni eggs. Crush biopsies from the lesions in the transverse colon showed only S. mansoni eggs. In conclusion, the examination of multiple crush biopsy specimens is a very sensitive and specific technique for species identification of Schistosoma, especially in mixed infections, and for defining the location and extent of the granulomas evoked by each species.

Eosinophilia in a Patient From South America

Asymptomatic eosinophilia is a common finding in returning travelers and immigrants from parasite-endemic areas. We present a 49-year-old man from Guyana who immigrated to the United States 4 years prior to examination. He had persistent asymptomatic eosinophilia, and multiple stool examinations were negative for ova and parasites. Although the list of parasitic diseases associated with eosinophilia is extensive, the differential diagnosis of asymptomatic eosinophilia with negative stool evaluations is rather limited. We discuss herein elements of the clinical history and examination essential for evaluating eosinophilia in patients at risk of parasitic diseases and present a simple algorithm to guide diagnostic testing. Despite the importance of repeated stool examinations for the presence of ova and parasites, in practice this test is not sensitive. Serologic testing for chronic parasitic infections is often necessary. Most cases without a definitive diagnosis can be conservatively managed with serial monitoring or empirically treated with antihelminthic therapy, but patients with an absolute eosinophil count of more than 3000/microL or more than 1500/microL for more than 6 months are at risk of end organ damage and should be referred for specialized parasitic and/or hematology consultation.

Increased Detection Rate of Strongyloides stercoralis by Repeated Stool Examinations Using the Agar Plate Culture Method

To clarify the efficacy of repeated stool examinations by the agar plate culture method for the detection of Strongyloides stercoralis infection, 4,071 stool samples collected from 2,406 patients > 50 years of age in Ryukyu University Hospital were examined. The cumulative detection rate of S. stercoralis infection was 4.7% (112/2,406). At the first, second, third, and beyond fourth examinations, the detection rates were 3.6% (86/2,406), 1.5% (12/786), 2.6% (10/392), and 2.0% (4/198), respectively. From these results, the cumulative detection rate was estimated to be 7.4% when three stool samples were examined for all patients. Our study showed that repeated stool examinations increase the sensitivity of detection of S. stercoralis infection.

Síndrome de malabsorción intestinal producido por Strongyloides stercoralis asociado con el síndrome de Loeffler en una mujer de 29 años de edad

We report a case of chronic infection by Strongyloides stercoralis in a 29-year-old Colombian woman who had been living in Spain for 2 years. The patient had recurrent abdominal pain and malabsorption syndrome. The diagnosis was made through intestinal biopsy in upper gastrointestinal endoscopy. Transport of the parasite through the lung parenchyma (Loeffler syndrome) was visible on simple chest X-ray. Bronchoalveolar lavage, bronchoalveolar aspirate and repeated stool examination were negative.

Severe strongyloidiasis in corticosteroid-treated patients: Case series and literature review

To describe the main features of severe strongyloidiasis in corticosteroid-treated patients We report on 3 cases of corticosteroid-treated patients with severe strongyloidiasis and review cases of severe strongyloidiasis in corticosteroid-treated patients reported in the literature. One hundred and fifty-one cases of severe strongyloidiasis complicated a therapy with corticosteroids were evaluated. The mean age of the patients was 48+/-17 years and 71% were men. Corticosteroids were given for hematological malignancies in 34 (23%), systemic lupus erythematosus or vasculitis in 27 (18%), and nephropathy or renal transplantation in 32 (21%). At time of infection, the mean daily dosage of prednisone-equivalent was 52+/-42 mg (median: 40 mg) and 84% of patients had received a cumulative dosage of prednisone-equivalent higher than 1000 mg. The total duration of treatment ranged from 4 days to 20 years (6 months or less: 69%). Non-specific gastro-intestinal symptoms were reported in 91% of these patients associated or not with pulmonary complaints. Low-grade fever was present in 54% of patients. Fifty-nine patients (39%) experienced severe bacterial or yeast infection during the course of severe strongyloidiasis. Peripheral eosinophilia was detected at presentation in 32% of patients. Strongyloidiasis was usually confirmed by repeated stool examinations. Thiabendazole was the treatment the more widely used. Eighty-nine patients (59%) deceased during the course of the disease. Severe strongyloidiasis is a risk in every corticosteroid-treated patient who has traveled to a soil-infested country, even if the contact was 30 years prior. This diagnosis should be suspected in patients who either experience unusual gastro-intestinal or pulmonary symptoms or suffer from unexplained Gram-negative bacilli sepsis.

A case of Ascaris suum visceral larva migrans diagnosed by using A. suum larval excretory-secretory (ES) antigen

A 42-y-old female presented with common cold-like symptoms. Laboratory data showed mild liver dysfunction together with peripheral blood eosinophilia. She was suspected of having a helminthic infection, however parasite eggs or larvae were not detected by repeated stool examinations. Eventually she transpired to have a high IgG antibody titer against excretory-secretary (ES) antigen of Ascaris suum larvae, but not of Toxocara canis larvae, suggesting that she had been suffering from visceral larva migrans (VLM) caused by A. suum. Her sickness improved without any treatment. Current results clearly highlight the usefulness of ES antigens derived from larvae of A. suum for the fine discrimination of VLM caused by A. suum and by T. canis. Application of A. suum derived ES antigens as a diagnostic tool may reveal the distinctive clinical features of VLM caused by A. suum.

Toward a complete immunity-inducing vaccine for schistosomiasis.

definitive mammalian host by penetrating intact skin. The cercariae adhere to the skin surface with the oral sucker and then penetrate the epidermis with the aid of muscular movement and lytic secretions discharged from the acetabular glands, losing their tail in the process and transforming into schistosomula. The schistosomula need 48-96 hr to negotiate the different layers of the stratified epidermis (Wilson, 1987; Sturrock, 1993, 2001). In this context, one wonders about the in vivo relevance of immunological data obtained with the in vitro-favored model of 3and 24-hr schistosomula because in vivo parasites of this age are still in the epidermis, well protected from the effect of blood components and cells. In the blood and lymphatic capillary-free, immunologically privileged environment of the epidermis, schistosomula shed the glycocalyx and undergo metabolic changes that end with replacement of the original, trilaminate tegumental membrane by a heptalaminate, double bilayer. Larvae merge into the dermis after acquiring resistance to the effect of complementand cell-mediated cytotoxicity (Dean, 1977; Samuelson et al., 1980; Dessein et al., 1981; Wilson, 1987). Focal inflammatory reactions elicited in the dermis may impede larval movement within the connective tissue, yet likely facilitate exit into the blood capillaries by increasing wall permeability. Until arrival in the liver, migrating larvae cannot feed as adults do because they lack a functional gut. They depend for their survival on energy obtained through the metabolism of reserve food and glucose and amino acids they obtain from the host via the apical tegument glucose and amino acid transporter, respectively (Skelly et al., 1994, 1999; Skelly and Shoemaker, 1996). Inflammatory cellular foci, induced by inflammatory mediators such as interferon-gamma (IFN-y) may delay or prevent the intravascular migration of larvae. Such impediment of movement is most significant in the lung capillaries, which have thin, unsupported walls that rupture easily, thus allowing extravasation of schistosomula into the air alveoli where they are trapped and die. The cellular foci are accumulations of lymphocytes and activated macrophages and their cytotoxic action is probably due to release of IFN-y, tumor necrosis factor-alpha, and nitric oxide (Crabtree and Wilson, 1986; Wilson et al., 1999). Indeed, IFN-y-dependent cellular immunity has been invoked as an important arm in defense against challenge infection with schistosomes in mice, immunized once or twice with radiation-attenuated larvae. Firm evidence supports the possibility of developing an effective vaccine against human schistosomiasis. Persons classed as endemic normals are continuously exposed to infective cercariae of S. mansoni and yet have no record of previous or current infection and appear uninfected as judged by repeated stool examination. There are numerous examples of lack of reinfection in adult humans that cannot be attributed solely to reduction in exposure to cercaria-infested water or to age-related factors. In such resistant humans, both T-helper 1 (IFN-y) and T-helper 2 (interleukin-4 and interleukin-5)-derived cytokines were found to be associated with the protective immune response to schistosomes (reviewed in McManus, 1999; Dunne and Mountford, 2001). Regarding the antibody arm of immunity, several studies have suggested that immunoglobulin E (IgE) is not required for the protective immune response in mice (Sher et al., 1990; El Ridi, Ragab et al., 2001). In contrast, a build up of IgE antibodies has been correlated with the development of resistance of humans to reinfection in some but not all studies (McManus, 1999; Dunne and Mountford, 2001; El Ridi, Shoemaker et al., 2001). The importance of IgE in protection against human schistosomiasis could be related to its ability to enhance the efficiency of the immune response (Mudde et al., 1990) rather than to its effector role. Indeed, IgE is thought to represent a major defense component against schistosomiasis, presumably by targeting effector cells against invading larvae in antibody-dependent cell-mediated cytotoxicity (ADCC) reactions. But there is limited evidence for ADCC efficacy in vivo because only the young schistosomula (epidermal stage) appear susceptible to the various killing mechanisms, whereas older parasites are almost impervious to ADCC-mediated immune attack. In support, the B-cell-dependent mechanism of protection in the radiation vaccine model, using mice that lack functional FcyRI, FcyRIII, and FceRI, did not appear to require FcR signaling (Jankovic et al., 1999). Yet, th absolute requirement for antibody response in protection against murin and human schistosomiasis has been amply documented (Hoffmann et al., 1999; Jankovic et al., 1999; McManus, 1999; Dunne and Mountford 2001; James and Colley, 2001). The mechanisms by which antibodies might function are unclear. It is worth noting that the antibody may impair larval viability and migration by interaction with critical sites in surface membrane-exposed molecules of importance for the parasite such as the glucose transporter, the amino acid permease and enzymes necessary for the generation of energy and membrane repair. Such neutralizing antibodies might even interfere with the welfare of adult worms in the liver.

Association between Schistosoma mansoni and hookworm infections among schoolchildren in Côte d'Ivoire

Infections with Schistosoma mansoni and hookworms are widespread in sub-Saharan Africa and the burden of disease associated with both parasites is enormous. Although there is a large overlap in their geographic distribution, little is known about the association between S. mansoni and hookworm infections and the underlying mechanisms. We explored this association among 325 schoolchildren from Côte d'Ivoire, by screening multiple stool specimens over consecutive days. We found a highly significant positive association between S. mansoni and hookworm infections with an adjusted odds ratio of 2.25 (95% confidence interval: 1.31–3.85; P=0.003). Increasing infection intensity of S. mansoni was significantly correlated with an increased likelihood of concomitant hookworm infections ( χ 2=20.72; P<0.001). Egg counts in stool specimens derived from a single day did not consistently reveal the positive association between the two parasites, which underlines the importance of repeated stool examinations. Several self-reported water contact patterns were significantly associated either with S. mansoni, hookworm or concomitant infections. Our findings are of considerable importance for tailoring effective health education messages that are readily adapted to the local epidemiological setting. Complemented with other control interventions, these measures might significantly reduce the burden caused by S. mansoni and hookworm infections.

Five-year impact of repeated praziquantel treatment on subclinical morbidity due to Schistosoma japonicum in China

We report the 5-year impact (1996–2001) of repeated praziquantel chemotherapy on subclinical morbidity related to Schistosoma japonicum infection. We repeated stool examinations and hepatosplenic ultrasonography in a cohort of 120 individuals living on an island with endemic infection in Dongting Lake, China. Prevalence of schistosome infection fell by 43% and intensity (geometric mean eggs per gram) declined by 80% over the 5 years. However, transmission persisted at a dangerously high rate of 13% per year for re-infection or new infection in the cohort. The prevalence of left-lobe enlargement and dilated portal vein fell significantly ( P < 0.01) to about half initial levels although a few patients progressed during the study period. At study endpoint, infection was nearly twice as common if the portal vein was dilated (23% versus 13%, respectively), but this association was not statistically significant ( P > 0.05). However, endpoint infection was even more strongly associated with left-lobe enlargement (57% versus 15%, P < 0.01). The proportions of subjects with improved parenchymal and periportal fibrosis were much higher than the proportions of subjects that progressed ( P < 0.05). Reduction of prevalence and intensity of infection, and improvement of subclinical morbidity, were benefits of repeated treatments. Further research is needed to understand why some patients developed fibrosis despite substantial reductions in egg counts and to evaluate the functional importance of residual subclinical morbidity after chemotherapy-based control in the lake and marshland area of China.

Diagnosing schistosomiasis.

The ideal diagnostic method for schistosomiasis detection seems to be still far from available. Paucity of egg output in low prevalence situations, low levels of circulating antigens in individuals with low intensity of infection and inadequate specificity of antibody detection systems outline pieces of a puzzle that challenges scientific efforts. Estimated prevalence, financial resources and operational reality must be taken into account when deciding the diagnostic method to be used. A combination of a screening step, using a fast strip test for antibody detection with a parasitological ratification step such as Kato-Katz repeated stool examination may serve as a diagnostic approach for a previously untreated low level endemic area. However, when eradication is the aim, and high financial investment is available, re-treatment may be based on the association between multiple stool examination and circulating antigen detection. Ethical aspects as well as cost-benefit rates between treatment and diagnosis approaches lead to the conclusion that in spite of the recent advances in simple administered and relatively safe drugs, treatment should only be performed when supported by appropriated diagnosis.

Case 17-1996

Presentation of CaseA 48-year-old man with the acquired immunodeficiency syndrome (AIDS) was admitted to the hospital because of bloody diarrhea and severe abdominal pain.Two years earlier, the patient had been found to have advanced AIDS and cytomegalovirus retinitis of the left eye. During the next two years, his CD4+ cell count was less than 10 per cubic millimeter, and he received ganciclovir as prophylaxis for the right eye. He had had diarrhea for many years; repeated stool examinations during the two years before admission yielded no diagnosis. Fatigue and intermittent fever were present for six months before admission. . . .

Eosinophilia caused by parasites.

Eosinophilia is defined as an absolute count of > 500 eosinophils per mm3 of peripheral blood. Eosinophilia is associated with many disorders, limiting its usefulness as a diagnostic tool in screening expatriates for parasite infections. In addition, only tissue-invasive helminthic parasites cause eosinophilia, which limits its general application as a screening tool for parasitic infections. Because eosinophilia may resolve spontaneously over time, the life cycle of parasites must be considered when evaluating eosinophilic patients, and repeated stool examinations or appropriate serology may be necessary to make the correct diagnosis. Future work on the risks associated with subclinical parasite infections would be helpful to place eosinophilia and other screening tests in proper perspective. Referral of difficult cases to specialists in travel medicine should be considered because detailed information about the geographic distribution and life cycle of helminthic parasites is often crucial to making the correct diagnosis.

Giardiasis

Giardiasis is one of the most common pathogenic intestinal protozoal infections worldwide. Giardia lamblia is the most frequently identified etiologic agent in outbreaks associated with the ingestion of surface water, often due to ineffective filtration or pretreatment. In addition to humans, other sources of infection include beavers, perhaps muskrats, and possibly domestic animals. A low infecting dose (10 to 25 cysts) is reported to be sufficient to produce human infection. Clinical manifestations range from asymptomatic to a transient or persistent acute stage, with steatorrhea, intermittent diarrhea, and weight loss, or to a subacute or chronic stage that can mimic gallbladder or peptic ulcer disease. Diagnosis is usually based on repeated stool examinations but examination of duodenal fluid or biopsy material may also be necessary. Enzyme immunoassay or indirect immunofluorescence methods for direct detection of antigen or whole organisms in clinical specimens have also been developed. These tests are reported to be more sensitive than routine stool examination. Demonstration of serum immunoglobulin M and G antibodies may help differentiate recent from past infection or help detect recurrence in individuals who have been treated previously. Serum immunoglobulin A levels may be a useful indicator of exposure in waterborne outbreaks of diarrhea. Drugs available for treatment within the United States include metronidazole, quinacrine hydrochloride, and furazolidone.