Mebendazole in parasitic infections other than those caused by soil-transmitted helminths

Albendazole and Mebendazole as Anti-Parasitic and Anti-Cancer Agents: an Update

The use of albendazole and mebendazole, i.e., benzimidazole broad-spectrum anthelmintics, in treatment of parasitic infections, as well as cancers, is briefly reviewed. These drugs are known to block the microtubule systems of parasites and mammalian cells leading to inhibition of glucose uptake and transport and finally cell death. Eventually they exhibit ovicidal, larvicidal, and vermicidal effects on parasites, and tumoricidal effects on hosts. Albendazole and mebendazole are most frequently prescribed for treatment of intestinal nematode infections (ascariasis, hookworm infections, trichuriasis, strongyloidiasis, and enterobiasis) and can also be used for intestinal tapeworm infections (taeniases and hymenolepiasis). However, these drugs also exhibit considerable therapeutic effects against tissue nematode/cestode infections (visceral, ocular, neural, and cutaneous larva migrans, anisakiasis, trichinosis, hepatic and intestinal capillariasis, angiostrongyliasis, gnathostomiasis, gongylonemiasis, thelaziasis, dracunculiasis, cerebral and subcutaneous cysticercosis, and echinococcosis). Albendazole is also used for treatment of filarial infections (lymphatic filariasis, onchocerciasis, loiasis, mansonellosis, and dirofilariasis) alone or in combination with other drugs, such as ivermectin or diethylcarbamazine. Albendazole was tried even for treatment of trematode (fascioliasis, clonorchiasis, opisthorchiasis, and intestinal fluke infections) and protozoan infections (giardiasis, vaginal trichomoniasis, cryptosporidiosis, and microsporidiosis). These drugs are generally safe with few side effects; however, when they are used for prolonged time (>14-28 days) or even only 1 time, liver toxicity and other side reactions may occur. In hookworms, Trichuris trichiura, possibly Ascaris lumbricoides, Wuchereria bancrofti, and Giardia sp., there are emerging issues of drug resistance. It is of particular note that albendazole and mebendazole have been repositioned as promising anti-cancer drugs. These drugs have been shown to be active in vitro and in vivo (animals) against liver, lung, ovary, prostate, colorectal, breast, head and neck cancers, and melanoma. Two clinical reports for albendazole and 2 case reports for mebendazole have revealed promising effects of these drugs in human patients having variable types of cancers. However, because of the toxicity of albendazole, for example, neutropenia due to myelosuppression, if high doses are used for a prolonged time, mebendazole is currently more popularly used than albendazole in anti-cancer clinical trials.

Cysticidal activity of praziquantel-mebendazole combination: In vitro and in vivo studies

The current pharmacological treatment of neurocysticercosis is based on two drugs, praziquantel (PZQ) and albendazole; however, suboptimal efficacy has been documented. Previous studies, have documented the activity of mebendazole (MBZ) against Taenia sp, and its capability to cross the blood-brain barrier. Considering this information and in an effort to search other options for neurocysticercosis treatment, the present study was designed to assess the in vitro and in vivo activity of the PZQ-MBZ combination against Taenia crassiceps metacestodes. For the in vitro studies T. crassiceps cysticerci (ORF strain) were used and the analysis of the combinations was performed using the Surface of Synergistic Interaction (SSI). For the in vivo evaluation the experimental infection model of T. crassiceps ORF in Balb-C mice was used. In vitro results showed that the combination of PZQ 121.6 nM-MBZ 5.1 nM exhibited the highest synergic cysticidal effect. In vivo, the PZQ-MBZ combination (25 mg/kg - 50 mg/kg, respectively) was more effective than each drug alone. The findings indicate that PZQ in combination with MBZ could be a promising alternative for the treatment of neurocysticercosis. Complementary studies are required to confirm its clinical applicability.

5-Nitroimidazole refractory giardiasis is common in Matanzas, Cuba and effectively treated by secnidazole plus high-dose mebendazole or quinacrine: a prospective observational cohort study

OBJECTIVE

To evaluate the effectiveness and tolerability of secnidazole combined with high-dose mebendazole for treatment of 5-nitroimidazole-resistant giardiasis.

METHOD

Adults with microscopically verified Giardia intestinalis monoinfection attending a secondary level hospital in Matanzas City, Cuba were prospectively included in a cohort. A recently introduced treatment ladder consisting of metronidazole as first-line treatment, followed by secnidazole, tinidazole, secnidazole plus mebendazole and quinacrine as second-to fifth-line treatments, respectively, was used. Adverse events and treatment success were determined by questioning and microscopy on concentrated stool samples, respectively on days 3, 5 and 7 after the end of treatment. If G. intestinalis was detected on day 3, 5 or 7, then the infection was classified as refractory and no further microscopy was performed.

RESULTS

A total of 456 individuals were included. Metronidazole, 500 mg three times daily for 5 days, cured 248/456 (54%) patients. A single 2-g secnidazole dose as second-line treatment cured 50/208 (24%) patients. A single 2-g tinidazole dose as third-line treatment cured 43/158 (27%) patients. Three rounds of 5-nitroimidazole therapy therefore cured 341/456 (75%) patients. Secnidazole plus mebendazole (200 mg every 8 hours for 3 days) cured 100/115 (87%) of nitroimidazole refractory infections. Quinacrine cured the remaining 15 patients. All treatments were well tolerated.

CONCLUSIONS

5-Nitroimidazole refractory giardiasis was common, indicating that an alternative first-line treatment may be needed. Retreatment of metronidazole refractory giardiasis with an alternative 5-nitroimidazole was suboptimal, indicating cross-resistance. Mebendazole plus secnidazole were well tolerated and effective for the treatment of 5-nitroimidazole refractory G. intestinalis infection in this setting.

Increased Prevalence of Cestode Infection Associated with History of Deworming among Primary School Children in Ethiopia

Mass deworming of school-aged children with anthelmintics has been recognized as an effective approach for reducing the burden of soil-transmitted helminth (STH) infections. However, the consequences of this intervention on nontargeted parasite populations sharing the same gastrointestinal niche are unclear. We conducted a cross-sectional survey among three primary schools in Sululta town, Ethiopia, to examine the association between students' histories of deworming treatment in the past 6 months and the prevalence of cestode and protozoan infections. An interviewer-led questionnaire administered to parents provided information on sociodemographic factors, and deworming status was ascertained from school records. Stool samples were collected from 525 children for microscopic examination. The independent associations of "any cestode" (positive either for Hymenolepis nana or Taenia spp. eggs) and "any protozoan" (positive either for Giardia lamblia or Entamoeba histolytica/Entamoeba dispar) with history of deworming were examined using logistic regression. Overall, 25.9% of children were infected with at least one intestinal parasite of which H. nana was the most common. In multivariate analyses, deworming in the past 6 months was positively associated with increased odds of both "any protozoan" and "any cestode" infections; the latter reached statistical significance (AOR = 1.83, 95% CI: 0.69-4.86, P = 0.220, AOR = 3.82, 95% CI: 1.17-12.73, P = 0.029, respectively). If this observed association is causal, a greater understanding of interspecies interactions within the gastrointestinal niche may elucidate possible consequences of mass deworming treatments against STHs on coexisting nontargeted parasites.

Efficacy of mebendazole in paediatric patients with giardiasis: A systematic review and meta-analysis

Mebendazole (MBZ), a benzimidazole compound, has received attention in treating patients with giardiasis because it has shown beneficial effects both in vitro and in vivo. The aim of this study was to assess with a systematic review and meta-analysis of randomized controlled trials (RCTs) the efficacy of MBZ compared to other antigiardial agents in children. We searched RCTs of MBZ for the treatment of Giardia infections published in PubMed and EBSCOhost. Application of inclusion and exclusion criteria, data extraction, and assessment of methodological quality were independently performed in duplicate. The primary outcome was the parasitological cure. We included 7 RCTs in the systematic review (639 patients). There was no clinical difference in the parasitological cure between MBZ and metronidazole (MTZ). The relative risk (RR) was 0.81 [95% Confidence Interval 0.61-1.09], with high heterogeneity (4 trials, I² = 81%). The prediction interval expected to cover the results of a new trial was wide enough (0.22-2.96) to support both a clinically relevant difference favouring either MBZ or MTZ. The decision to support any treatment should be based not only on efficacy but also safety and cost. Although our results suggest that MBZ may be an effective treatment option for children with Giardia infection, they should also be interpreted and translated into clinical practice with caution, as the evidence is based on a limited number of RCTs presenting high heterogeneity.

Effectiveness and Tolerability of 3-Day Mebendazole Treatment of Giardia duodenalis Infection in Adults and Children: Two Prospective, Open-Label Phase IV Trials

BACKGROUND

Giardia duodenalis is the most common intestinal pathogenic protozoan infection reported in humans. Both in vitro studies and 4 separate, sequential, comparative clinical trials conducted by our group in Cuba demonstrated mebendazole activity against G. duodenalis infection in both children and adults.

OBJECTIVE

The 2 additional, prospective, open-label, Phase IV follow-up studies reported here were performed to further assess the effectiveness and safety profile of mebendazole in the outpatient treatment of G. duodenalis infection.

METHODS

Assenting children (n = 522) whose guardians gave permission and consenting adults (n = 423) diagnosed with G. duodenalis infection were given mebendazole (200 mg 3 times daily for 3 days). Medical histories and stool samples were obtained and physical/laboratory examinations were performed pretreatment then repeated on days 3, 5, and 7 after treatment completion. The evaluation of efficacy (ie, cure) was based on parasitologic response to therapy. Participants were considered cured, if no Giardia trophozoites or cysts were found in any of the 3 posttreatment fecal specimens evaluated by direct wet mounts and/or after Ritchie concentration techniques.

RESULTS

No participant refused to be enrolled and all returned for follow-up examinations. At the end of the treatment, stool samples were negative in 450 out of 522 children (86.2%) and 392 of 423 adults (92.7%). Treatment was well tolerated. In adults, the only adverse effect reported was abdominal pain (6.2%). Side effects reported in children included abdominal pain (5.6%), nausea (2.9%), and vomiting (2.3%). Reported side effects were all mild, transient, and self-limited and did not require discontinuation of treatment or additional medication.

CONCLUSIONS

Mebendazole may be an effective alternative treatment of G. duodenalis infections in both children and adults.

Chronic schistosomiasis suppresses HIV-specific responses to DNA-MVA and MVA-gp140 Env vaccine regimens despite antihelminthic treatment and increases helminth-associated pathology in a mouse model

Future HIV vaccines are expected to induce effective Th1 cell-mediated and Env-specific antibody responses that are necessary to offer protective immunity to HIV infection. However, HIV infections are highly prevalent in helminth endemic areas. Helminth infections induce polarised Th2 responses that may impair HIV vaccine-generated Th1 responses. In this study, we tested if Schistosoma mansoni (Sm) infection altered immune responses to SAAVI candidate HIV vaccines (DNA and MVA) and an HIV-1 gp140 Env protein vaccine (gp140) and whether parasite elimination by chemotherapy or the presence of Sm eggs (SmE) in the absence of active infection influenced the immunogenicity of these vaccines. In addition, we evaluated helminth-associated pathology in DNA and MVA vaccination groups. Mice were chronically infected with Sm and vaccinated with DNA+MVA in a prime+boost combination or MVA+gp140 in concurrent combination regimens. Some Sm-infected mice were treated with praziquantel (PZQ) prior to vaccinations. Other mice were inoculated with SmE before receiving vaccinations. Unvaccinated mice without Sm infection or SmE inoculation served as controls. HIV responses were evaluated in the blood and spleen while Sm-associated pathology was evaluated in the livers. Sm-infected mice had significantly lower magnitudes of HIV-specific cellular responses after vaccination with DNA+MVA or MVA+gp140 compared to uninfected control mice. Similarly, gp140 Env-specific antibody responses were significantly lower in vaccinated Sm-infected mice compared to controls. Treatment with PZQ partially restored cellular but not humoral immune responses in vaccinated Sm-infected mice. Gp140 Env-specific antibody responses were attenuated in mice that were inoculated with SmE compared to controls. Lastly, Sm-infected mice that were vaccinated with DNA+MVA displayed exacerbated liver pathology as indicated by larger granulomas and increased hepatosplenomegaly when compared with unvaccinated Sm-infected mice. This study shows that chronic schistosomiasis attenuates both HIV-specific T-cell and antibody responses and parasite elimination by chemotherapy may partially restore cellular but not antibody immunity, with additional data suggesting that the presence of SmE retained in the tissues after antihelminthic therapy contributes to lack of full immune restoration. Our data further suggest that helminthiasis may compromise HIV vaccine safety. Overall, these findings suggested a potential negative impact on future HIV vaccinations by helminthiasis in endemic areas.

Chronic parasitic worm infections are thought to reduce the efficacy of vaccines. Given that HIV and worm infections are common in sub-Saharan Africa (SSA) and their geographical distribution vastly overlaps, it is likely that future HIV vaccines in SSA will be administered to a large proportion of people with chronic worm infections. This study examined the impact of S. mansoni worm infections on the immunogenicity of candidate HIV vaccines in a mouse model. S. mansoni worm-infected animals had lower magnitudes of HIV vaccine responses compared with uninfected animals and elimination of worms by praziquantel treatment prior to vaccination conferred only partial restoration of normal immune responses to vaccination. The presence of S. mansoni eggs trapped in the tissues in the absence of live infection was associated with poor vaccine responses. In addition, this study found that effective immunization with some HIV vaccine regimens could potentially worsen worm-associated pathology when given to infected individuals. These novel findings suggest further research in HIV vaccines and future vaccination policies regarding the current clinical vaccines and future HIV vaccination with respect to parasitic worm infections especially in SSA.

Epidemiology of intestinal parasitic infections in school children in Ghazni Province, eastern Afghanistan

OBJECTIVE

To estimate the prevalence of intestinal parasites and their species in Afghan school children and to establish appropriate treatment methods for detected pathogens.

METHODS

Parasitological examination of stool samples collected from 1369 children aged 8-18, students of the Jahan Malika High School in Ghazni Province in eastern Afghanistan, was conducted in the period November 2013-April 2014. Three stool samples were collected from each patient every second day; the samples were fixed in 10% formalin and tested by light microscopy using the methods of direct smear in Lugol's solution, decantation in distilled water, and Fülleborn's flotation.

RESULTS

Of 535 examined children (39.1% of the study group) were infected with nematodes (n=324), cestodes (n=118), trematodes (n=12), and protozoa (n=228), 132 were diagnosed with co-infections (mainly ascariasis+giardiasis, ascariasis+hymenolepiasis) and received single or combined therapy.

CONCLUSIONS

The Afghan community is an example of population characterized by a high rate of parasitic infections. Owing to high prevalence of multiple infections among inhabitants of Afghanistan, it seems that a mass deworming campaign with a single-dose chemotherapy may prove ineffective in eradicating intestinal parasites in the local population.

In vivo anthelmintic efficacy of Aloe ferox, Agave sisalana, and Gunnera perpensa in village chickens naturally infected with Heterakis gallinarum

The study was conducted to determine the anthelmintic efficacy of Aloe ferox, Agave sisalana, and Gunnera perpensa against Heterakis gallinarum in village chickens. The chickens naturally infected with H. gallinarum were randomly divided into 14 groups of eight chickens and orally administered distilled water (negative control), mebendazole (positive control), and graded levels (50-, 100-, 200-, and 400-mg/kg doses) of the three plant extracts. At days 0, 7, and 14, the floatation technique was used to determine fecal egg counts and H. gallinarum worms from chicken ceca were counted at days 0 and 14. Egg count reduction percentage (ECR%) was high at day 7 for all the test materials except for A. sisalana (100 mg/kg) that had 33%. At day 14, ECR% was high for all the other test materials save for A. ferox (200 mg/kg), mebendazole, and distilled water which was 50, 32, and 50%, respectively. A. ferox (200 mg/kg), G. perpensa (200 and 400 mg/kg), and A. sisalana (50 and 100 mg/kg) had the highest (85, 78, 74, 86, and 73%, respectively) worm count reduction percentage. The plants had anthelmintic properties. Advocacy and utilization of these plants in improving the health of village chickens could lead to increased productivity, boosting profits for the poultry industry thereby enabling it to meet the supply of animal protein and enhance livelihoods. It is imperative to determine compounds in the crude extracts of these medicinal plants which are responsible for the anthelmintic activities and their mechanism of action.

Drug repurposing and human parasitic protozoan diseases

Parasitic diseases have an enormous health, social and economic impact and are a particular problem in tropical regions of the world. Diseases caused by protozoa and helminths, such as malaria and schistosomiasis, are the cause of most parasite related morbidity and mortality, with an estimated 1.1 million combined deaths annually. The global burden of these diseases is exacerbated by the lack of licensed vaccines, making safe and effective drugs vital to their prevention and treatment. Unfortunately, where drugs are available, their usefulness is being increasingly threatened by parasite drug resistance. The need for new drugs drives antiparasitic drug discovery research globally and requires a range of innovative strategies to ensure a sustainable pipeline of lead compounds. In this review we discuss one of these approaches, drug repurposing or repositioning, with a focus on major human parasitic protozoan diseases such as malaria, trypanosomiasis, toxoplasmosis, cryptosporidiosis and leishmaniasis.

Mebendazole reduces vascular smooth muscle cell proliferation and neointimal formation following vascular injury in mice

Mebendazole is an antihelminthic drug that exerts its effects via interference with microtubule function in parasites. To determine the utility of mebendazole as a potential treatment for vascular diseases involving proliferation of vascular smooth muscle cells, the effects of mebendazole on vascular smooth muscle cell proliferation were tested in vitro and in a mouse model of arterial injury. In vitro, mebendazole inhibited proliferation and migration of murine vascular smooth muscle cells and this was associated with altered intracellular microtubule organization. To determine in vivo effects of mebendazole following vascular injury, femoral arterial wire injury was induced in wild-type mice treated with either mebendazole or placebo control. Compared with placebo-treated mice, mebendazole-treated mice formed less neointima at the site of injury. Mebendazole is effective at inhibiting vascular smooth muscle cell proliferation and migration, and neointimal formation following arterial injury in mice.

Albendazole versus metronidazole in the treatment of adult giardiasis: a randomized, double-blind, clinical trial

BACKGROUND

Albendazole (ABZ) is a benzimidazole carbamate compound currently in use for human medical practice against enterobiasis and soil-transmitted helminthiasis (STH); However, its spectrum of activity is broad and goes beyond these infections.

OBJECTIVE

This study compares the efficacy and safety of ABZ versus metronidazole (MTZ) in human giardiasis.

RESEARCH DESIGN AND METHODS

A randomized, double-blind, clinical trial was carried out at the Centre of Hygiene, Epidemiology and Microbiology in Matanzas City, Cuba. Adult patients with confirmed symptomatic G. duodenalis mono-infection were randomly assigned to receive either ABZ [400 mg daily (n = 75)] or MTZ [250 mg t.i.d. (n = 75)], both for 5 days. Follow-up fecal samples were obtained at 3, 5, 7 days after treatment end.

RESULTS

The efficacy was similar for both treatment groups: ABZ (82.6%) and MTZ (85.3%); p > 0.05. Side-effects including bitter taste, headache, vomiting and dizziness were significantly higher in the MTZ group. Abdominal pain was significantly higher in ABZ group.

CONCLUSION

ABZ was found as effective as MTZ in the treatment of G. duodenalis infections in adult patients from Cuba and could be a useful drug in areas where co-infection with STH infections is common.