Potential risks associated with the proposed widespread use of Tamiflu

Removal of oseltamivir (Tamiflu) and other selected pharmaceuticals from wastewater using a granular bioplastic formulation entrapping propagules of Phanerochaete chrysosporium

The capacity of the ligninolytic fungus Phanerochaete chrysosporium to degrade a wide variety of environmentally persistent xenobiotics has been largely reported in the literature. Beside other factors, one barrier to a wider use of this bioremediation fungus is the availability of effective formulations that ensure easy preparation, handling and application. In this series of laboratory experiments, we evaluated the efficiency of a granular bioplastic formulation entrapping propagules of P. chrysosporium for removal of four selected pharmaceuticals from wastewater samples. Addition of inoculated granules to samples of the wastewater treatment plant of Bologna significantly increased the removal of the antiviral drug oseltamivir (Tamiflu), and the antibiotics, erythromycin, sulfamethoxazol, and ciprofloxacin. Similar effects were also observed in effluent water. Oseltamivir was the most persistent of the four active substances. After 30d of incubation, approximately two times more oseltamivir was removed in bioremediated wastewater than controls. The highest removal efficiency of the bioplastic formulation was observed with the antibiotic ciprofloxacin. Microbiological DNA-based analysis showed that the bioplastic matrix supported the growth of P. chrysosporium, thus facilitating its adaptation to unusual environment such as wastewater.

Features of the new pandemic influenza A/H1N1/2009 virus: virology, epidemiology, clinical and public health aspects

PURPOSE OF REVIEW

The emergence of the pandemic A/H1N1/2009 influenza virus has enabled preexisting pandemic influenza plans to be put into action. This review examines the clinical and public health impact of this new virus.

RECENT FINDINGS

Although early figures suggested that this pandemic virus was causing higher morbidity and mortality than seasonal influenza viruses, subsequent studies have found it to cause milder disease in most cases. Yet, there are some groups with increased risk of serious disease from this new pathogen. The widespread use of antiviral agents, prophylactically and therapeutically, has led to the sporadic emergence of drug resistance, though this is still rare. Nonpharmacological public health interventions for containment and mitigation have been relatively ineffective in limiting the rapid, global spread of this pathogen. Recently, the focus has been on the manufacture and distribution of various specific vaccines against this new virus, and the care of severely ill patients admitted to intensive care.

SUMMARY

As this virus continues to infect new members of the global population, it may eventually become just one of the annual circulating seasonal influenza viruses. Until then, it will be prudent to continue to monitor it closely for any signs of enhanced transmissibility and virulence.

Antiviral drugs in wastewater and surface waters: a new pharmaceutical class of environmental relevance?

An analytical method was developed for the determination of nine antiviral drugs (acyclovir, abacavir, lamivudine, nevirapine oseltamivir, penciclovir, ribavirin, stavudine, zidovudine) and one active metabolite (oseltamivir carboxylate) in raw and treated wastewater as well as in surface water using LC/ESI tandem MS detection. Relative recoveries exceeded 80% and limits of quantification ranged between 0.2 and 10 ng L(-1). Matrix effects were compensated by the use of stable isotope labeled surrogate standards and optimized chromatographic separation on a Hydro-RP column. All antiviral drugs, except ribavirin, were detected in raw wastewater. A significant reduction in concentrations was observed for acyclovir, lamivudine, and abacavir in treated wastewater indicating a substantial removal, while nevirapine, zidovudine and oseltamivir were found in similar concentrations in raw and treated wastewater. Concentrations in river waters were in the lower ng L(-1)-range, with a maximum of 190 and 170 ng L(-1) for acyclovir and zidovudine, respectively in the Hessian Ried. Estimated total compound loads in the Ruhr river ranged between <0.1 and 16.5 g d(-1) while for the Rhine river values between 370 and 1800 g d(-1) were determined. The ratios of oseltamivir to oseltamivir carboxylate were approximately a factor of 10 higher for the Rhine than for the other rivers and streams indicating a significant contribution from other sources such as discharges from manufacturing facilities.

Oseltamivir carboxylate, the active metabolite of oseltamivir phosphate (Tamiflu), detected in sewage discharge and river water in Japan

BACKGROUND

Oseltamivir phosphate (OP; Tamiflu) is a prodrug of the anti-influenza neuraminidase inhibitor oseltamivir carboxylate (OC) and has been developed for the treatment and prevention of both A and B strains of influenza. The recent increase in OP resistance in influenza A virus (H1N1; commonly called "swine flu") has raised questions about the widespread use of Tamiflu in seasonal epidemics and the potential ecotoxicologic risk associated with its use in the event of a pandemic.

OBJECTIVES

The objectives of this study were to develop an analytical method for quantitative determination of OC in sewage treatment plant (STP) effluent and receiving river water, and to investigate the occurrence of OC in STP effluent and river water in Japan during a seasonal flu outbreak.

METHODS

We developed an analytical method based on solid-phase extraction followed by liquid chromatography-tandem mass spectrometry. Using this method, we analyzed samples from three sampling campaigns conducted during the 2008-2009 flu season in Kyoto City, Japan.

RESULTS

The highest concentration of OC detected in STP discharge was 293.3 ng/L from a conventional activated-sludge-based STP; however, we detected only 37.9 ng/L from an advanced STP with ozonation as a tertiary treatment. In the receiving river water samples, we detected 6.6-190.2 ng/L OC, during the peak of the flu season.

CONCLUSION

OC is present in STP effluent and river water only during the flu season. Ozonation as tertiary treatment in STP will substantially reduce the OC load in STP effluent during an influenza epidemic or pandemic.

Evaluation of a rapid molecular algorithm for detection of pandemic influenza A (H1N1) 2009 virus and screening for a key oseltamivir resistance (H275Y) substitution in neuraminidase

BACKGROUND

Rapid and specific molecular tests for identification of the recently identified pandemic influenza A/H1N1 2009 virus as well as rapid molecular tests to identify antiviral resistant strains are urgently needed.

OBJECTIVES

We have evaluated the performance of two novel reverse transcriptase polymerase chain reactions (RT-PCRs) targeting specifically hemagglutinin and neuraminidase of pandemic influenza A/H1N1 virus in combination with a conserved matrix PCR. In addition, we investigated the performance of a novel discrimination RT-PCR for detection of the H275Y resistance mutation in the neuraminidase gene.

STUDY DESIGN

Clinical performance of both subtype specific RT-PCR assays was evaluated through analysis of 684 throat swaps collected from individuals meeting the WHO case definition for the novel pandemic influenza virus. Analytical performance was analyzed through testing of 10-fold serial dilutions of RNA derived from the first Dutch sequenced and cultured confirmed case of novel pandemic influenza infection. Specificity and discriminative capacities of the H275Y discrimination assay were performed by testing wild type and recombinant H275Y pandemic influenza.

RESULTS

121 throat swaps collected from April 2009 to July 2009 were positive by at least two out of three RT-PCRs, and negative for the seasonal H3/H1 subtype specific RT-PCR assays. 117 of these were tested positive for all three (Ct-values from 15.1 to 36.8). No oseltamivir resistance was detected.

CONCLUSIONS

We present a sensitive and specific approach for detection of pandemic influenza A/H1N1 2009 and a rapid RT-PCR assay detecting a primary oseltamivir resistance mutation which can be incorporated easily into clinical virology algorithms.

Fate and removal of pharmaceuticals and illicit drugs in conventional and membrane bioreactor wastewater treatment plants and by riverbank filtration

Pharmaceutically active compounds (PhACs) and drugs of abuse (DAs) are two important groups of emerging environmental contaminants that have raised an increasing interest in the scientific community. A number of studies revealed their presence in the environment. This is mainly due to the fact that some compounds are not efficiently removed during wastewater treatment processes, being able to reach surface and groundwater and subsequently, drinking waters. This paper reviews the data regarding the levels of pharmaceuticals and illicit drugs detected in wastewaters and gives an overview of their removal by conventional treatment technologies (applying activated sludge) as well as advanced treatments such as membrane bioreactor. The paper also gives an overview of bank filtration practices at managed aquifer recharge sites and discusses the potential of this approach to mitigate the contamination by PhACs and DAs.

An environmental risk assessment for oseltamivir (Tamiflu) for sewage works and surface waters under seasonal-influenza- and pandemic-use conditions

In the event of an influenza pandemic, anti-viral medications such as oseltamivir (Tamiflu) are expected to be used in high amounts over a duration of several weeks. Oseltamivir has been predicted to reach high concentrations in surface waters and sewage works. New oseltamivir environmental fate and toxicity studies permit an environmental risk assessment (ERA) under seasonal- and pandemic-use scenarios. The environmental fate data for sewage works (no removal), surface waters (no significant degradation), and water/sediment systems (>50% primary degradation in 100 days) were used for the derivation of new predicted environmental concentrations (PECs) for western Europe and the River Lee catchment in the UK. Existing worst-case PECs for western Europe, the River Lee catchment in the UK and the Lower Colorado basin in the USA under pandemic conditions (< or =98.1 microg/L for surface waters, < or =348 microg/L for sewage works) were also considered for the ERA. PECs were compared with predicted no-effect concentrations (PNECs) based on new chronic ecotoxicity data (no observed effect concentration for algae, daphnia, and fish > or =1 mg/L). Based on all PEC/PNEC risk ratios, no significant risk is evident to surface waters or sewage works during both regular seasonal-use and high pandemic-use of oseltamivir.

Detection of the antiviral drug oseltamivir in aquatic environments

Oseltamivir (Tamiflu®) is the most important antiviral drug available and a cornerstone in the defence against a future influenza pandemic. Recent publications have shown that the active metabolite, oseltamivir carboxylate (OC), is not degraded in sewage treatment plants and is also persistent in aquatic environments. This implies that OC will be present in aquatic environments in areas where oseltamivir is prescribed to patients for therapeutic use. The country where oseltamivir is used most is Japan, where it is used to treat seasonal flu. We measured the levels of OC in water samples from the Yodo River system in the Kyoto and Osaka prefectures, Japan, taken before and during the flu-season 2007/8. No OC was detected before the flu-season but 2–58 ng L⁻¹ was detected in the samples taken during the flu season. This study shows, for the first time, that low levels of oseltamivir can be found in the aquatic environment. Therefore the natural reservoir of influenza virus, dabbling ducks, is exposed to oseltamivir, which could promote the evolution of viral resistance.

Use of oseltamivir after influenza infection is associated with reduced incidence of recurrent adverse cardiovascular outcomes among military health system beneficiaries with prior cardiovascular diseases

BACKGROUND

Influenza infection has been associated with increased risk of adverse cardiac and cerebral vascular outcomes. Oseltamivir, a treatment for influenza, has been shown to decrease the severity of an influenza episode, but few data exist regarding its potentially protective effect against recurrent vascular outcomes among influenza patients with a history of vascular disease.

METHODS AND RESULTS

Electronic healthcare service and pharmacy records for 37,482 TRICARE beneficiaries, aged 18 and older, with a coded history of cardiovascular (CV) disease and a subsequent diagnosis of influenza from October 1, 2003, through September 30, 2007, were examined. Subjects were grouped according to whether they had filled a prescription for oseltamivir within 2 days of their influenza diagnosis. The incidence of recurrent CV events within 30 days after the influenza diagnosis among oseltavmivir-treated and untreated subjects was 8.5% and 21.2%, respectively (P<0.005). Subject age was a persistent and significant contributor to the likelihood of recurrent CV outcomes. After controlling for the differences in demographics among treated and untreated cohorts using a propensity-scored logistic regression model, a statistically significant protective effect was associated with oseltamivir treatment (odds ratio, 0.417; 95% CI, 0.349 to 0.498).

CONCLUSIONS

Our findings suggests that oseltamivir treatment for influenza is associated with significant decrease in the risk of recurrent CV events in subjects with a history of CV disease. These findings merit confirmation in further prospective and controlled studies. Meanwhile, in patients with CV disease, strict adherence with current practice guidelines for prevention and treatment of influenza is recommended.

Environmental risk and toxicology of human and veterinary waste pharmaceutical exposure to wild aquatic host-parasite relationships

Pollution of the aquatic environment by human and veterinary waste pharmaceuticals is an increasing area of concern but little is known about their ecotoxicological effects on wildlife. In particular the interactions between pharmaceuticals and natural stressors of aquatic communities remains to be elucidated. A common natural stressor of freshwater and marine organisms are protozoan and metazoan parasites, which can have significant effects on host physiology and population structure, especially under the influence of many traditional kinds of toxic pollutants. However, little is known about the effects of waste pharmaceuticals to host-parasite dynamics. In order to assess the risk waste pharmaceuticals pose to aquatic wildlife it has been suggested the use of toxicological data derived from mammals during the product development of pharmaceuticals may be useful for predicting toxic effects. An additional similar source of information is the extensive clinical studies undertaken with numerous classes of drugs against parasites of human and veterinary importance. These studies may form the basis of preliminary risk assessments to aquatic populations and their interactions with parasitic diseases in pharmaceutical-exposed habitats. The present article reviews the effects of the most common classes of pharmaceutical medicines to host-parasite relationships and assesses the risk they may pose to wild aquatic organisms. In addition the effects of pharmaceutical mixtures, the importance of sewage treatment, and the risk of developing resistant strains of parasites are also assessed.

Environmental fate of the antiviral drug Tamiflu in two aquatic ecosystems

The antiviral drug Tamiflu (Oseltamivir Phosphate, OP), has been indicated by the World Health Organization as a first-line defense in case of an avian influenza pandemic. Recent studies have demonstrated that Oseltamivir Carboxylate (OC), the active metabolite of the prodrug OP, has the potential to be released into water bodies. The present laboratory study focused on basic processes governing the environmental fate of OC in surface water from two contrasting aquatic ecosystems of northern Italy, the River Po and the Venice lagoon. Results of this study confirmed the potential of OC to persist in surface water. However, addition of 5% of sediments resulted in rapid OC degradation. Estimated half-life of OC in water/sediment of the River Po was 15 days. After three weeks of incubation at 20 degrees C, more than 8% of (14)C-OC evolved as (14)CO(2) from water/sediment samples of the River Po and Venice lagoon. At the end of the 21-day incubation period, more than 65% of the (14)C-residues were recovered from the liquid phase of both Po and Venice water/sediment samples. OC was moderately retained onto coarse sediments from the two sites. In water/sediment samples of the River Po and Venice lagoon treated with (14)C-OC, more than 30% of the (14)C-residues remained water-extractable after three weeks of incubation. The low affinity of OC to sediments suggests that presence of sediments would not reduce its bioavailability to microbial degradation.

Risk perceptions related to SARS and avian influenza: theoretical foundations of current empirical research

BACKGROUND

The outbreak of severe acute respiratory syndrome in 2003 and the subsequent emergence of the H5N1 virus have highlighted the threat of a global pandemic influenza outbreak. Planning effective public health control measures for such a case will be highly dependent on sound theory-based research on how people perceive the risks involved in such an event.

PURPOSE

The present article aims to review theoretical models and concepts underlying current empirical research on pandemic influenza risk perception.

METHOD

A review was conducted based on 28 empirical studies from 30 articles which were published between 2003 and 2007.

RESULTS

Concepts of risk perception mostly seemed more pragmatic than theory-based and were highly heterogeneous, for instance, in terms of conceptualizing risk perception as an exclusively cognitive or as a cognitive and emotional phenomenon or whether the concept was dominated by expectancy or expectancy and value components. Similarly, the majority of studies investigating risk perceptions and protective behaviors were not model-based.

CONCLUSIONS

The current body of knowledge can only provide preliminary insights. Unlike the reviewed studies, which were mostly launched as a rapid response to outbreak situations, future research will have to invest more strongly into theoretical work to provide sounder evidence.

The environmental fate of the antiviral drug oseltamivir carboxylate in different waters

Since the efficacy of oseltamivir carboxylate (OC) as the active metabolite of Tamiflu has been demonstrated against influenza viruses and even against the avian influenza virus (H5N1), millions of Tamiflu treatment courses are stockpiled worldwide. This was done not at least to follow the recommendations of the World Health Organization (WHO) to cope with a viral influenza pandemic. Concentrations up to 26-32 microg l(-1) OC in river catchment areas in the United States and in the United Kingdom had been predicted recently for a pandemic case, assuming an apparent persistence of the Tamiflu metabolite. Such concentrations may involve the risk of generation of antiviral resistance. But there is still a lack of data concerning the stability of OC in a surface water environment. Under this aspect these predictions have to be validated with concrete facts about the environmental fate of OC. In this article we summarized the results of three different daylight exposure experiments with OC in different waters under sterile and non-sterile conditions simulating shallow water processes at the latitude of approximately 52 degrees N. Using a river water solution containing 50 microg l(-1) OC under non-sterile conditions a half-life time of 17.8 days was observed. Direct photolysis plays no or only a negligible role for the decomposition of OC. Degradation of OC seems to occur as a combination of microbial metabolism and indirect photolysis.

Meeting report: risk assessment of tamiflu use under pandemic conditions

On 3 October 2007, 40 participants with diverse expertise attended the workshop Tamiflu and the Environment: Implications of Use under Pandemic Conditions to assess the potential human health impact and environmental hazards associated with use of Tamiflu during an influenza pandemic. Based on the identification and risk-ranking of knowledge gaps, the consensus was that oseltamivir ethylester-phosphate (OE-P) and oseltamivir carboxylate (OC) were unlikely to pose an ecotoxicologic hazard to freshwater organisms. OC in river water might hasten the generation of OC-resistance in wildfowl, but this possibility seems less likely than the potential disruption that could be posed by OC and other pharmaceuticals to the operation of sewage treatment plants. The work-group members agreed on the following research priorities: a) available data on the ecotoxicology of OE-P and OC should be published; b) risk should be assessed for OC-contaminated river water generating OC-resistant viruses in wildfowl; c) sewage treatment plant functioning due to microbial inhibition by neuraminidase inhibitors and other antimicrobials used during a pandemic should be investigated; and d) realistic worst-case exposure scenarios should be developed. Additional modeling would be useful to identify localized areas within river catchments that might be prone to high pharmaceutical concentrations in sewage treatment plant effluent. Ongoing seasonal use of Tamiflu in Japan offers opportunities for researchers to assess how much OC enters and persists in the aquatic environment.

Evolution of drug resistance in multiple distinct lineages of H5N1 avian influenza

Some predict that influenza A H5N1 will be the cause of a pandemic among humans. In preparation for such an event, many governments and organizations have stockpiled antiviral drugs such as oseltamivir (Tamiflu). However, it is known that multiple lineages of H5N1 are already resistant to another class of drugs, adamantane derivatives, and a few lineages are resistant to oseltamivir. What is less well understood is the evolutionary history of the mutations that confer drug resistance in the H5N1 population. In order to address this gap, we conducted phylogenetic analyses of 676 genomic sequences of H5N1 and used the resulting hypotheses as a basis for asking 3 molecular evolutionary questions: (1) Have drug-resistant genotypes arisen in distinct lineages of H5N1 through point mutation or through reassortment? (2) Is there evidence for positive selection on the codons that lead to drug resistance? (3) Is there evidence for covariation between positions in the genome that confer resistance to drugs and other positions, unrelated to drug resistance, that may be under selection for other phenotypes? We also examine how drug-resistant lineages proliferate across the landscape by projecting or phylogenetic analysis onto a virtual globe. Our results for H5N1 show that in most cases drug resistance has arisen by independent point mutations rather than reassortment or covariation. Furthermore, we found that some codons that mediate resistance to adamantane derivatives are under positive selection, but did not find positive selection on codons that mediate resistance to oseltamivir. Together, our phylogenetic methods, molecular evolutionary analyses, and geographic visualization provide a framework for analysis of globally distributed genomic data that can be used to monitor the evolution of drug resistance.

Adherence with oseltamivir chemoprophylaxis among workers exposed to poultry during avian influenza outbreaks in southern Israel

OBJECTIVES

To determine adherence with recommended pre- and post-exposure oseltamivir prophylaxis (OP) among workers exposed to poultry during five simultaneous avian influenza (AI) H5N1 outbreaks in poultry farms in southern Israel in March 2006, as well as the efficiency of the distribution system of oseltamivir in the community.

DESIGN

Epidemiological investigation identified 201 workers exposed to poultry during AI outbreaks. They were interviewed by a public health nurse regarding adherence with recommended OP, symptoms, and possible side effects. Data were collected on type of exposure, age, sex, rate of adherence with OP, and reasons for non-adherence. For eight workers, paired sera were drawn for the determination of antibodies to H5. Data were collected on the efficiency of the distribution of oseltamivir tablets to workers in the community.

RESULTS

High adherence with OP (87.6%) was found among poultry workers during outbreaks of AI, with no difference by type of exposure, age, or sex. There was a low rate of side effects of OP (1.5%). No exposed workers developed AI and none of the eight who had paired sera drawn showed seroconversion. The distribution of OP in the community was inefficient, with 27.7% of the tablets 'lost' or returned unusable.

CONCLUSIONS

These data emphasize the importance of developing efficient targeted distribution systems in the community for OP, in order to prevent human infection during AI outbreaks.

Defeating pathogen drug resistance: guidance from evolutionary theory

Many of the greatest challenges in medicine and public health involve the evolution of drug resistance by pathogens. Recent advances in the theory of natural selection suggest that there are two broad classes of pathogen traits that can be targeted by drugs or vaccines. The first class, consisting of traits that benefit the individual organisms bearing them, causes a strong evolutionary response and the rapid emergence of drug resistance. The second class, consisting of traits that benefit groups of pathogen organisms including the individual provider, causes a weaker evolutionary response and less drug resistance. Although most previous drug development has targeted the first class, it would be advantageous to focus on the second class as targets for drug and vaccine development. Specific examples and test cases are discussed.

Antiviral oseltamivir is not removed or degraded in normal sewage water treatment: implications for development of resistance by influenza A virus

Oseltamivir is the main antiviral for treatment and prevention of pandemic influenza. The increase in oseltamivir resistance reported recently has therefore sparked a debate on how to use oseltamivir in non pandemic influenza and the risks associated with wide spread use during a pandemic. Several questions have been asked about the fate of oseltamivir in the sewage treatment plants and in the environment. We have assessed the fate of oseltamivir and discuss the implications of environmental residues of oseltamivir regarding the occurrence of resistance. A series of batch experiments that simulated normal sewage treatment with oseltamivir present was conducted and the UV-spectra of oseltamivir were recorded. Findings: Our experiments show that the active moiety of oseltamivir is not removed in normal sewage water treatments and is not degraded substantially by UV light radiation, and that the active substance is released in waste water leaving the plant. Our conclusion is that a ubiquitous use of oseltamivir may result in selection pressures in the environment that favor development of drug-resistance.