A Safety and Tolerability Study of Nitazoxanide in HIV-HCV Treatment Failures

* ELIGIBILITY CRITERIA: To be eligible for participation on this protocol, a participant must satisfy all of the following conditions: Be greater than or equal to 18 years old and have an identifiable Primary Care Provider. Have either documentation of HIV-1 infection by licensed enzyme-linked immunosorbent assay (ELISA) and confirmed by a Western Blot or HIV RNA of 1,000 copies/mLor greater. Have documentation of chronic HCV (CHC) infection by demonstration of a positive test for hepatitis C antibocy and HCV RNA of 2,000 IU/mL or greater Have histopathologic features consisten with CHC at the time of enrollment. A liver biopsy done for a participant with 36 months prior to his or her participant may be used as the baseline biopsy. Participants can opt out of a biopsy if they had one or more than 36 months prior and have a contraindication, sucha as receiving chronic anticoagulation therapy. Participants with decompensated liver disease are excluded from study. Are co-infected infected with HCV genotype 1 and HIV viruses. 1. Relapsers: Participants who had an undetectable HCV RNA (\< 10 IU/mL) at the end of prior treatment (ETR) but have detectable HCV RNA by Week 72 or thereafter. 2. Non-responders: Participants who have received at least 12 weeks of treatment with any IFN alfa 2a or 2b with ribavirin and have not achieved either a 2 log (10) drop in HCV viral levels at week 12 (null responder) nor has not achieved a HCV RNA below the level of detection by Week 24 (\< 10 IU/mL). 3. Washout period from prior treatment of at least 3 months. Participants with CD(4) cell counts greater than or equal to 100 cells/mm(3) Capacity to understand and sign or thumbprint the Informed Consent document, as well as willingness to comply with the study requirements and clinic policies. Absolute neutrophil count \> 1,000 cells/mm3. Platelets \> 50,000/mm3. Hemoglobin \> 10.5 mg/dL. Not pregnant or breast-feeding. Serum pregnancy test must be negative 2 weeks prior to Day -28 and to Day 0 prior to dosing with study medications for female participants. If the participant is able to become pregnant, then she must use 2 effective methods of contraception during the study. Effective contraceptive methods include abstinence, surgical sterilization of either partner, barrier methods such as diaphragm, condom, cap, or sponge, or use of hormonal contraception with an anti-HIV regimen that will not alter metabolism of hormonal contraception. This is advised on the basis of using ribavirin, which may have a potential teratogenic effect on the fetus in pregnant women. NTZ had not been studied during lactation. Be willing to not become pregnant until 6 months after completion of ribavirin therapy. Male participants who are not documented to be sterile agree to either abstain from intercourse or consistently and correctly use a condom while their female partner (if applicable) agrees to use one of the appropriate medically accepted methods of birth control listed above from the date of screening until 6 months after their last dose of ribavirin. Participants with documented illicit drug use must demonstrate ability to adhere to HIV medication (with an undetectable or stable HIV viral load) and their prior primary care provider appointments (more than 80% as scheduled). Be willing to abstain from alcohol use during the trial and enter treatment program if necessary. Be able to learn to safely inject medication, be able to find another person or a clinic to inject the medication for him/her, or is willing to come to the clinic for weekly injections. Be willing to allow stored blood or tissue samples to be used in the future. EXCLUSION CRITERIA A participant will be ineligible to participate on this study if any of the following criteria are met: A participant cannot be on other experimental therapies (including expanded access/compassionate use of antiretrovirals) for 28 days prior to Day -28 and during his/her participation in this protocol. Mixed genotypes (e.g., 1 \& 2, 1 \& 3,1 \& 4). Mixed genotype 1a/1b will be enrolled. Has any other known, or clinically suspected, cause of liver disease, including active hepatitis B. For participants with cirrhosis, a Child Turcotte Pugh score \> 7, or Child's B or C cirrhosis. Has a prothrombin time International Normalized Ratio (PT-INR) \> 2 and is not on chronic anti-coagulation medications, or has a history of hemophilia. Has had an organ transplantation other than cornea or hair. Has an estimated creatinine clearance (estimated glomerular flow rate) \< 50 mL/min. For a participant with higher than 20 ng/mL of alpha-fetoprotein, a negative ultrasound or computerized tomography scan to rule out hepatoma is required for enrollment. Has any neoplastic disease EXCEPT for (1) Kaposi's sarcoma not requiring systemic chemotherapy, (2) any non-metastatic skin cancer that has been resected or (3) non-metastatic cervical or anal cancer that has been resected. Has evidence of severe cardiac disease (greater than or equal to Grade 3 congestive cardiac failure, symptomatic coronary artery disease, significant arrhythmias, or uncontrolled hypertension) despite intervention or medical therapy. Has evidence of severe chronic pulmonary disease with functional impairment or a DLCO (diffusing capacity of the lung for carbon monoxide) less than or equal to 70% at baseline. Has a severe psychiatric disorder that would interfere with the adherence to protocol requirements, and that is not stably treated with risk of decompensation. Has evidence of autoimmune disorders including inflammatory bowel diseases, psoriasis, and optic neuritis. Has evidence of an uncontrolled seizure disorder defined as more than 1 episode of generalized seizure within the past year. Has chronic pancreatitis. Has severe retinopathy, as determined by the ophthalmologist. Has any hemoglobinopathy (e.g., Thalassemia, sickle cell disease). Is currently taking didanosine or d4T as part of antiretroviral regimen. If total bilirubin is greater than 1.5 mg/dL then direct bilirubin can be no more than 70% of the total, up to a direct bilirubin of 2.0 mg/dL. Concurrent use of any immunosuppressive therapy, including systemic steroids (prednisone equivalent of \> 10 mg/day) for a duration of 6 weeks or more within 6 months prior to enrollment. Inhaled steroids will be allowed, even with ritonavir. Has active systemic infections other than HCV and HIV. Has a hepatic mass suggestive of hepatocellular carcinoma as detected by ultrasound scan, dual-phase computerized tomography, or magnetic resonance imaging. Has evidence of moderate or heavy alcohol use (\> 50 grams/day), or substance abuse, within the past 6 months that potentially could interfere with participant compliance. (Urine toxicology will be completed at screening.) Currently uses warfarin, ganciclovir, isoniazid, pyrazinamide, rifabutin, rifampin/rifampicin, thalidomide, or theophylline. Has a history of esophageal or gastric varices. Has any systemic illness that will make it unlikely that the participant will be able to return for the required study visits. Has evidence of gastrointestinal malabsorption, chronic nausea, or vomiting. The participant is the male partner of a pregnant woman and does not always use a condom during intercourse. Women who are pregnant. Women who are breast-feeding. Has a hypersensitivity to NTZ, interferon products, or ribavirin. Has ingested silymarin (milk thistle), s-adenosylmethionine (SAM-e), glycyrrhizin, Sho-saiko-to (SST), or other herbal supplements that may be either liver beneficial or toxic, within 28 days prior to Day -28.