Global socioeconomic impact of cystic echinococcosis

Echinococcus granulosus: in vitro effectiveness of warm water on protoscolices

Hydatid disease is one of the most important helminthic diseases worldwide. Hydatid cysts may be found anywhere in the body. The most effective treatment of hydatid cyst is surgical operation. Spillage of live protoscolices during the operation is the major cause of recurrence. Instillation of scolicidal agent into hydatid cyst is the most commonly employed measure to prevent this complication. To date, many scolicidal agents have been used for inactivation of the hydatid cyst content, however, most common scolicidal agents may cause unacceptable side-effects, limiting their use. In this study the scolicidal effect of warm water (45, 50, 55, and 60 °C) at different exposure times (1, 2, 3, 4, 5, 6, 8, 10, 12, and 15 min) is investigated. Protoscolices were collected aseptically from sheep livers containing hydatid cyst. Viability of protoscolices was determined by 0.1% eosin staining. Even though the highest scolicidal activity of warm water at 45 °C was 40.4% at the end of 15 min, the best scolicidal effect (100%) of warm water at 50, 55, and 60 °C was obtained after 5, 2, and 1 min, respectively. The results of this in vitro study showed that warm water at 50-60 °C can be regarded as an effective scolicidal agent. Warm water is commonly available, easily prepared, and inexpensive. In vivo scolicidal activity of warm water and also the possible side effects need further investigation.

Echinococcus canadensis G7 (pig strain): an underestimated cause of cystic echinococcosis in Austria

Anamnesis data of 104 patients with Cystic Echinococcosis were correlated retrospectively with the detected species/strain of Echinococcus. Ninety-two percent (N = 23) of autochthonous Austrian and 33% (N = 9) of patients with former Yugoslavian (YU) origin were infected with E. canadensis G7, the pig strain. All patients originating from Turkey harbored E. granulosus G1, the sheep strain. All E. canadensis G7-infected patients showed small liver cysts (ø 5.9 cm), only one of them an additional lung cyst. The median age at the time of operation of the Austrian patients was 55 years, of the Turkish patients 30 years, and of the former YU patients 23 years in the E. canadensis and 42 years in the E. granulosus-infected patients, respectively. The unexpected high number of E. canadensis G7-infected patients and the immigrants' young age show the importance of E. canadensis as a cause of human Cystic Echinococcosis in Central Europe and accordingly this new species has to be included into future echinococcosis control programs.

Expert consensus for the diagnosis and treatment of cystic and alveolar echinococcosis in humans

The earlier recommendations of the WHO-Informal Working Group on Echinococcosis (WHO-IWGE) for the treatment of human echinococcosis have had considerable impact in different settings worldwide, but the last major revision was published more than 10 years ago. Advances in classification and treatment of echinococcosis prompted experts from different continents to review the current literature, discuss recent achievements and provide a consensus on diagnosis, treatment and follow-up. Among the recognized species, two are of medical importance -Echinococcus granulosus and Echinococcus multilocularis - causing cystic echinococcosis (CE) and alveolar echinococcosis (AE), respectively. For CE, consensus has been obtained on an image-based, stage-specific approach, which is helpful for choosing one of the following options: (1) percutaneous treatment, (2) surgery, (3) anti-infective drug treatment or (4) watch and wait. Clinical decision-making depends also on setting-specific aspects. The usage of an imaging-based classification system is highly recommended. For AE, early diagnosis and radical (tumour-like) surgery followed by anti-infective prophylaxis with albendazole remains one of the key elements. However, most patients with AE are diagnosed at a later stage, when radical surgery (distance of larval to liver tissue of >2cm) cannot be achieved. The backbone of AE treatment remains the continuous medical treatment with albendazole, and if necessary, individualized interventional measures. With this approach, the prognosis can be improved for the majority of patients with AE. The consensus of experts under the aegis of the WHO-IWGE will help promote studies that provide missing evidence to be included in the next update.

Widespread co-endemicity of human cystic and alveolar echinococcosis on the eastern Tibetan Plateau, northwest Sichuan/southeast Qinghai, China

Cystic echinococcosis (CE) or hydatid disease is known to be cosmopolitan in its global distribution, while alveolar echinococcosis (AE) is a much rarer though more pathogenic hepatic parasitic disease restricted to the northern hemisphere. Both forms of human echinococcosis are known to occur on the Tibetan Plateau, but the epidemiological characteristics remain poorly understood. In our current study, abdominal ultrasound screening programs for echinococcosis were conducted in 31 Tibetan townships in Ganze and Aba Tibetan Autonomous Prefectures of northwest Sichuan Province during 2001-2008. Hospital records (1992-2006) in a major regional treatment centre for echinococcosis in Sichuan Province were also reviewed. Of 10,186 local residents examined by portable ultrasound scan, 645 (6.3%) were diagnosed with echinococcosis: a prevalence of 3.2% for CE, 3.1% for AE and 0.04% for dual infection (both CE and AE). Human cystic and alveolar echinococcosis in pastoral areas was highly co-endemic, in comparison to much lower prevalences in semi-pastoral or farming regions. The high ultrasound prevalence in these co-endemic areas in northwest Sichuan Province was also reflected in the hospital study, and hospital records furthermore indicated another possible highly co-endemic focus in Guoluo Prefecture of Qinghai Province, located at the border of northwest Sichuan. These chronic cestode zoonoses constitute an unparalleled major public health problem for pastoral Tibetan communities, and pose great difficulties for adequate treatment access and effective transmission control in such remote regions.

Primary hydatid cyst of the gallbladder: a case report

Introduction

Echinococcosis, or hydatid disease, is endemic in some regions of the world, and has been a common pathology of surgical wards in Kosovo. Primary hydatid cyst of the gallbladder is an unusual and very rare localization of hydatid disease. So far, only five cases that fulfill the criteria of primary gallbladder hydatidosis have been published in the English medical literature.

Case presentation

We report a case of a 39-year-old Kosovan Albanian woman referred to the Abdominal Surgery Division of the University Clinical Center of Kosovo for "a calcified hydatid cyst of the liver with gallbladder involvement". Her history was significant for chronic right upper quadrant pain, characterized as intermittently colicky pain, accompanied by nausea. The patient underwent right subcostal laparotomy. Intra-operatively, a calcified primary hydatid cyst of the gallbladder was found. Its pericyst was tightly attached to the liver. Complete pericystectomy with cholecystectomy followed. The histopathology confirmed the presence of calcified hydatid cyst of the gallbladder, and that the cyst had developed entirely extra-mucosally. Five year follow-up showed no recurrence of disease.

Conclusion

Primary hydatid cyst of the gallbladder is a very rare clinical entity. Accurate preoperative diagnostic localization is not always easy, particularly in centers with limited diagnostic tools.

In vitro effectiveness of acidic and alkline solutions on scolices of hydatid cyst

The most confident way for treatment of hydatid cyst is surgical operation. Spillage of the cyst contents during the operation is the major cause of recurrence after hydatid cyst surgery. Instillation of scolicidal agent into hydatid cyst is the most commonly employed measure to prevent this complication. In the present study, the scolicidal effect of highly acidic and alkaline solutions is investigated. Protoscoleces were collected aseptically from sheep livers containing hydatid cyst. Acidic solutions with pH 1, 2, 3, and 4 and alkaline solutions with pH 11, 12, 13, and 14 were used for 5,10, and 15 min in the experiments. Viability of protoscoleces was assessed by 0.1% eosin staining. Scolicidal effect of acidic solution with pH 1 after 5 min and with pH 2 and 3 after 10 min was 100%. Scolicidal effect of acidic solution with pH 2 and 3 after 5 min was 99.6% and 98.7%, respectively. Acidic solution with pH 4 after 5, 10, and 15 min killed 15.5%, 21.5%, and 22.6% of protoscoleces, respectively. Alkaline solution with pH 14 after 5 min and with pH 13 after 15 min killed all protoscoleces. The scolicidal effect of alkaline solution with pH 13 after 5 and 10 min was also 97.5% and 99.7%, respectively. These values for alkaline solution with pH 12 were 29.33%, 33.44% and 37.09%, respectively. The scolicidal effect of solution with pH 11 was 24.5%, 30.5%, and 31.3%, respectively. Although the in vitro scolicidal effect of highly acidic or alkaline solutions was satisfactory in our study, in vivo efficacy of these solutions and also possible side effects, remain to be more investigated.

Application of an in vitro drug screening assay based on the release of phosphoglucose isomerase to determine the structure-activity relationship of thiazolides against Echinococcus multilocularis metacestodes

OBJECTIVES

The disease alveolar echinococcosis (AE), caused by the larval stage of the cestode Echinococcus multilocularis, is fatal if treatment is unsuccessful. Current treatment options are, at best, parasitostatic, and involve taking benzimidazoles (albendazole, mebendazole) for the whole of a patient's life. In conjunction with the recent development of optimized procedures for E. multilocularis metacestode cultivation, we aimed to develop a rapid and reliable drug screening test, which enables efficient screening of a large number of compounds in a relatively short time frame.

METHODS

Metacestodes were treated in vitro with albendazole, the nitro-thiazole nitazoxanide and 29 nitazoxanide derivatives. The resulting leakage of phosphoglucose isomerase (PGI) activity into the medium supernatant was measured and provided an indication of compound efficacy.

RESULTS

We show that upon in vitro culture of E. multilocularis metacestodes in the presence of active drugs such as albendazole, the nitro-thiazole nitazoxanide and 30 different nitazoxanide derivatives, the activity of PGI in culture supernatants increased. The increase in PGI activity correlated with the progressive degeneration and destruction of metacestode tissue in a time- and concentration-dependent manner, which allowed us to perform a structure-activity relationship analysis on the thiazolide compounds used in this study.

CONCLUSIONS

The assay presented here is inexpensive, rapid, can be used in 24- and 96-well formats and will serve as an ideal tool for first-round in vitro tests on the efficacy of large numbers of antiparasitic compounds.

Population medicine and control of epidemics

Population medicine is an important component of veterinary care in livestock (farm animals) and companion animals (pets). This chapter covers some of the chemotherapeutic approaches undertaken at population level to control infectious diseases in domestic animals. Optimisation of health, productivity and welfare in livestock commonly entails implementation of whole-herd or whole-flock strategies to effectively counter the negative impact of infectious diseases. Gastro-intestinal and liver parasites of grazing cattle and sheep are endemic in most parts of the world and can result in significant production losses. Strategically timed anthelmintic treatments are instituted with the double objective of reducing worm burdens in infected animals and ensuring reduction of pasture contamination with infective larvae. Mastitis is another major endemic problem, particularly in cattle, which causes significant economic losses to dairy farmers globally. As a painful inflammatory condition of the cow's udder, clinical mastitis also raises animal welfare concerns. Prevention of clinical mastitis requires rigorous post-milking hygiene, identification and culling of chronically infected cows, attention to the cow's environment and therapeutic management of udder health during the dry period. A third condition that can cause high levels of morbidity and mortality is bacterial respiratory disease. Pneumonia in young livestock is often exacerbated by stressful transportation and co-mingling of animals from different herds. The welfare consequences and production losses can be significant. Antimicrobial treatment of pneumonic animals and, when appropriate, of in-contact animals living in the same air-space is an integral part of whole-herd respiratory disease management. The role of the veterinary profession is to also ensure that principles of population medicine are understood and adhered to by pet owners. The increase in pet ownership and the importance of the human-animal bond in modern developed societies give rise to zoonotic risks, which require vigilance and intervention. Regular internal parasite control in dogs and cats, particularly in endemic areas, contributes to animal welfare and minimises public health hazards.

Update on cystic hydatid disease

PURPOSE OF REVIEW

Cystic echinococcosis, or cystic hydatidosis, is a complex, chronic disease with a cosmopolitan distribution. In humans, its clinical spectrum ranges from asymptomatic infection to severe, rarely even fatal disease. Four approaches in clinical management exist: surgery, percutaneous techniques and drug treatment for active cysts, and the so-called watch and wait approach for inactive cysts. Allocation of patients to these treatments should be based on cyst stage, size and location, available clinical expertise and comorbidities. However, clinical decision algorithms, efficacy, relapse rates, and costs have never been properly evaluated.We review the currently available evidence for clinical decision-making and discuss ways to improve standards of care of one of the most neglected infectious diseases.

RECENT FINDINGS

Data are mostly derived from case series and small clinical trials, and treatment guidelines remain at the level of expert opinion. No single high-quality comparative clinical trial of the four treatment options is available to resolve important questions such as stage-specific allocation of treatments, adverse events and long-term relapse rates. Recent work is beginning to acknowledge this problem.

SUMMARY

Currently, four treatment modalities are available for cystic echinococcosis. The level of evidence on which clinicians have to rely is low. For the time being patients should thus be treated in referral centres. Proper comparative clinical trials are urgently needed.

Neglected and endemic zoonoses

Endemic zoonoses are found throughout the developing world, wherever people live in close proximity to their animals, affecting not only the health of poor people but often also their livelihoods through the health of their livestock. Unlike newly emerging zoonoses that attract the attention of the developed world, these endemic zoonoses are by comparison neglected. This is, in part, a consequence of under-reporting, resulting in underestimation of their global burden, which in turn artificially downgrades their importance in the eyes of administrators and funding agencies. The development of cheap and effective vaccines is no guarantee that these endemic diseases will be eliminated in the near future. However, simply increasing awareness about their causes and how they may be prevented-often with very simple technologies-could reduce the incidence of many endemic zoonoses. Sustainable control of zoonoses is reliant on surveillance, but, as with other public-sector animal health services, this is rarely implemented in the developing world, not least because of the lack of sufficiently cheap diagnostics. Public-private partnerships have already provided advocacy for human disease control and could be equally effective in addressing endemic zoonoses.

The impacts of livestock diseases and their control on growth and development processes that are pro-poor

Poverty is now at the heart of development discourse; we discuss how it is measured and understood. We next consider the negative and positive impacts of livestock on pro-poor development. Taking a value-chain approach that includes keepers, users and eaters of livestock, we identify diseases that are road blocks on the 'three livestock pathways out of poverty'. We discuss livestock impacts on poverty reduction and review attempts to prioritize the livestock diseases relevant to the poor. We make suggestions for metrics that better measure disease impact and show the benefits of more rigorous evaluation before reviewing recent attempts to measure the importance of disease to the poor. High impact of a disease does not guarantee high benefits from its control; other factors must be taken into consideration, including technical feasibility and political desirability. We conclude by considering how we might better understand and exploit the roles of livestock and improved animal health by posing three speculative questions on the impact of livestock diseases and their control on global poverty: how can understanding livestock and poverty links help disease control?; if global poverty reduction was the aim of livestock disease control, how would it differ from the current model?; and how much of the impact of livestock disease on poverty is due to disease control policy rather than disease itself?

Echinococcus metacestodes as laboratory models for the screening of drugs against cestodes and trematodes

Among the cestodes, Echinococcus granulosus, Echinococcus multilocularis and Taenia solium represent the most dangerous parasites. Their larval stages cause the diseases cystic echinococcosis (CE), alveolar echinococcosis (AE) and cysticercosis, respectively, which exhibit considerable medical and veterinary health concerns with a profound economic impact. Others caused by other cestodes, such as species of the genera Mesocestoides and Hymenolepis, are relatively rare in humans. In this review, we will focus on E. granulosus and E. multilocularis metacestode laboratory models and will review the use of these models in the search for novel drugs that could be employed for chemotherapeutic treatment of echinococcosis. Clearly, improved therapeutic drugs are needed for the treatment of AE and CE, and this can only be achieved through the development of medium-to-high throughput screening approaches. The most recent achievements in the in vitro culture and genetic manipulation of E. multilocularis cells and metacestodes, and the accessability of the E. multilocularis genome and EST sequence information, have rendered the E. multilocularis model uniquely suited for studies on drug-efficacy and drug target identification. This could lead to the development of novel compounds for the use in chemotherapy against echinococcosis, and possibly against diseases caused by other cestodes, and potentially also trematodes.

Flubendazole in cystic echinococcosis therapy: pharmaco-parasitological evaluation in mice

Cystic echinococcosis (CE) caused by the parasite Echinococcus granulosus is an important public health problem worldwide. Flubendazole has shown poor in vivo efficacy against CE in humans and mice. However, flubendazole causes marked in vitro damage on E. granulosus protoscoleces. The goals of the current work were: a) to compare the plasma pharmacokinetic behaviour of flubendazole formulated as a hydroxipropyl-beta-cyclodextrin aqueous solution or as a carboxymethyl celullose suspension, both given by the oral route to mice, b) to compare flubendazole clinical efficacy in secondary CE in mice after its administration as both formulations, c) to evaluate the flubendazole-induced morphological changes in hydatid cysts recovered from infected mice treated with both drug formulations. Flubendazole administration as a solution resulted in significantly higher plasma maximum concentration (C(max)) and area under the concentration-time curve (AUC) values compared to those obtained after the flubendazole-suspension treatment. This enhanced drug availability correlated with an increased efficacy against secondary CE in mice observed for the flubendazole-solution formulation, while the suspension formulation did not reach differences with the untreated control group. Similar ultrastructural changes were observed in cysts recovered from flubendazole (both formulations) treated mice after 3, 6 and 9months of infection, although the damage extension was greater after treatment with the flubendazole-solution formulation.

Echinococcosis: diagnosis and diagnostic interpretation in population studies

Diagnosis is a basic component of population studies on echinococcosis. Other than careful necropsy in animals, there is no perfect gold standard. In the definitive host, techniques for direct parasite identification include copro-antigen and copro-DNA detection. In intermediate hosts, necropsy is typically used. In humans, diagnostic imaging and serology are both widely employed. The use of multiple parallel testing or an additional confirmatory test (or tests) in a diagnostic strategy can overcome the lack of a perfect gold standard. This will yield valuable information at population and individual levels, providing the study is well designed and any shortcomings of the tests are incorporated into the analysis. Here, we discuss analytical approaches to population studies of echinococcosis.

A retrospective survey of hydatidosis in livestock in Arusha, Tanzania, based on abattoir data during 2005-2007

A 3-year (2005-2007) retrospective study was carried out to investigate the occurrence of cystic echinococcosis (CE) in cattle and shoats (sheep and goats) slaughtered at Arusha municipal abattoir, Tanzania. A total of 115,186 cattle and 99,401 shoats were slaughtered. Cattle liver, lungs, spleen and heart condemnation rate was 16.35%, 13.04%, 2.09% and 3.06% respectively while 17.63%, 7.63%, 0.38% and 0.04% of shoats' liver, lungs, spleen and heart respectively were condemned. A highly significant (p < 0.001) cystic echinococcosis (CE) infection rate was recorded in shoats (6.02%) than in cattle (4.2%) probably because of differences in grazing patterns. Cattle lungs were more affected by CE (22.5%) than liver (19.7%) while shoats liver were found to be more affected (21%) than the lungs (19.3). A significant (p < 0.001) higher CE infection rate was observed in cattle spleen (15.5%) than shoats (9.7%). There was no significant (p > 0.05) difference between condemnation rates due to hydatidosis during rain and dry seasons probably because of chronicity of the disease. The study have established that CE is prevalent in animals slaughtered at Arusha abattoir and causes higher condemnation rates of edible offals. This merit for more extensive epidemiological investigations to better determine the prevalence, economic impact and public health importance of the disease in the region.

Isolation of antibodies specific to a single conformation-dependant antigenic determinant on the EG95 hydatid vaccine

EG95 is a recombinant vaccine protein that elicits protection against hydatid disease in sheep. Previous studies have shown that the host-protective epitopes on EG95 depend on correct conformation and cannot be represented by simple “linear” peptides. By screening random peptide phage display libraries with polyclonal antibodies directed against conformation-dependant epitopes of EG95, we have selected a number of peptides that mimic these epitopes. The selected peptides did not show sequence homology to EG95. Antigen binding assays involving these peptides have provided evidence of at least four conformationally-dependant epitope regions on EG95. One of the selected peptides, E100, has been used to purify antibodies from anti-sera raised in sheep vaccinated with EG95. This yielded monospecific antibodies capable of recognizing recombinant EG95 in ELISA and native EG95 in Western blot assays. This antibody was demonstrated to be effective in antibody-dependant complement-mediated in vitro killing of Echinococcus granulosus oncospheres. Peptide E100 may represent the basis for a quality control assay for EG95 production, and has the potential to become a component of a synthetic peptide-based vaccine against E. granulosus.

Vaccination of dogs against Echinococcus granulosus: a means to control hydatid disease?

Hydatid disease continues to be a substantial cause of morbidity and mortality worldwide. Elimination is difficult with current control options, but reducing egg production by Echinococcus granulosus (Eg) in canines might help to reduce transmission in areas where the parasite is endemic. Recently obtained data using recombinant protein-based and live attenuated Salmonella vaccines are preliminary but encouraging and auger well for the future development of an effective dog vaccine against Eg, although much additional work is required before this becomes a reality. New approaches to control and for the prevention of hydatidosis have been described recently, and important additional gains should be expected if the efficacy of the dog vaccines is confirmed and leads to their incorporation into future control options.

DNA damage, RAD9 and fertility/infertility of Echinococcus granulosus hydatid cysts

Hydatidosis, caused by the larval stage of the platyhelminth parasite Echinococcus granulosus, affects human and animal health. Hydatid fertile cysts are formed in intermediate hosts (human and herbivores) producing protoscoleces, the infective form to canines, at their germinal layers. Infertile cysts are also formed, but they are unable to produce protoscoleces. The molecular mechanisms involved in hydatid cysts fertility/infertility are unknown. Nevertheless, previous work from our laboratory has suggested that apoptosis is involved in hydatid cyst infertility and death. On the other hand, fertile hydatid cysts can resist oxidative damage due to reactive oxygen and nitrogen species. On these foundations, we have postulated that when oxidative damage of DNA in the germinal layers exceeds the capability of DNA repair mechanisms, apoptosis is triggered and hydatid cysts infertility occurs. We describe a much higher percentage of nuclei with oxidative DNA damage in dead protoscoleces and in the germinal layer of infertile cysts than in fertile cysts, suggesting that DNA repair mechanisms are active in fertile cysts. rad9, a conserved gene, plays a key role in cell cycle checkpoint modulation and DNA repair. We found that RAD9 of E. granulosus (EgRAD9) is expressed at the mRNA and protein levels. As it was found in other eukaryotes, EgRAD9 is hyperphosphorylated in response to DNA damage. Our results suggest that molecules involved in DNA repair in the germinal layer of fertile hydatid cysts and in protoscoleces, such as EgRAD9, may allow preserving the fertility of hydatid cysts in the presence of ROS and RNS.

Alveolar echinococcosis: from a deadly disease to a well-controlled infection. Relative survival and economic analysis in Switzerland over the last 35 years

BACKGROUND/AIMS

Alveolar echinococcosis (AE) is a serious liver disease. The aim of this study was to explore the long-term prognosis of AE patients, the burden of this disease in Switzerland and the cost-effectiveness of treatment.

METHODS

Relative survival analysis was undertaken using a national database with 329 patient records. 155 representative cases had sufficient details regarding treatment costs and patient outcome to estimate the financial implications and treatment costs of AE.

RESULTS

For an average 54-year-old patient diagnosed with AE in 1970 the life expectancy was estimated to be reduced by 18.2 and 21.3 years for men and women, respectively. By 2005 this was reduced to approximately 3.5 and 2.6 years, respectively. Patients undergoing radical surgery had a better outcome, whereas the older patients had a poorer prognosis than the younger patients. Costs amount to approximately Euro108,762 per patient. Assuming the improved life expectancy of AE patients is due to modern treatment the cost per disability-adjusted life years (DALY) saved is approximately Euro6,032.

CONCLUSIONS

Current treatments have substantially improved the prognosis of AE patients compared to the 1970s. The cost per DALY saved is low compared to the average national annual income. Hence, AE treatment is highly cost-effective in Switzerland.

Infectivity of Echinococcus granulosus protoscolices under different conditions of temperature and humidity

The aim of this study was to examine the effect of different temperatures and humidities on the infectivity of Echinococcus granulosus protoscolices. Eighteen dogs (6 groups, n = 3 each) were fed with offal mince harbouring approximately 20,000 protoscolices of E. granulosus of different viabilities. Dogs were infected with E. granulosus protoscolices of: (1) 5% viability at -10 degrees C and 50% relative humidity (RH); (2) 30% viability at 0 degrees C and 60% RH; (3) 20% viability at +10 degrees C and 65% RH; (4) 15% viability at +30 degrees C and 75% RH; (5) 11% viability at +40 degrees C and 80% RH; (6) 68% viability (control group). Dogs in each group were necropsied at 29-49 days post-infection. Mean intensities of E. granulosus recovered from dogs were 256.7 +/- 60.3 in the second group; 32.7 +/- 7.1 in the third group; 40.3 +/- 15.5 in the fourth group and 1533 +/- 513 in the control group. However, no parasites were recovered from the first and fifth groups. Results obtained in the present study show that larval stages could be infective for 1 to 4 weeks during spring, autumn or winter months when maximal temperatures are approximately 0-10 degrees C. In conclusion, cold-storage depots in slaughterhouses and abattoirs where sheep carcasses might be discarded should be kept at -20 degrees C for 2-3 days, dogs should be properly controlled and adequate control programmes must be established in areas where the disease is endemic.

Diagnosis of cystic echinococcosis, central Peruvian Highlands

High prevalence was confirmed by ultrasonography, radiography, and 2 serologic tests, although usefulness of serologic testing in the field was limited.

We evaluated prevalence of cystic echinococcosis (CE) in a central Peruvian Highland district by using 4 diagnostic methods: ultrasonography for 949 persons, radiography for 829, and 2 serologic tests for 929 (2 immunoblot formats using bovine hydatid cyst fluid [IBCF] and recombinant EpC1 glutathione S-transferase [rEpC1-GST] antigens). For the IBCF and rEpC1-GST testing, prevalence of liver and pulmonary CE was 4.7% and 1.1% and seropositivity was 8.9% and 19.7%, respectively. Frequency of seropositive results for IBCF and rEpC1-GST testing was 35.7% and 16.7% (all hepatic cysts), 47.1% and 29.4% (hepatic calcifications excluded), and 22.2% and 33.3% (lung cysts), respectively. Weak immune response against lung cysts, calcified cysts, small cysts, and cysts in sites other than lung and liver might explain the poor performance of the serodiagnostic tests. We confirm that CE is highly endemic to Peru and emphasize the limited performance of available serologic assays in the field.

Estimating the burden of rhodesiense sleeping sickness during an outbreak in Serere, eastern Uganda

BACKGROUND

Zoonotic sleeping sickness, or HAT (Human African Trypanosomiasis), caused by infection with Trypanosoma brucei rhodesiense, is an under-reported and neglected tropical disease. Previous assessments of the disease burden expressed as Disability-Adjusted Life Years (DALYs) for this infection have not distinguished T.b. rhodesiense from infection with the related, but clinically distinct Trypanosoma brucei gambiense form. T.b. rhodesiense occurs focally, and it is important to assess the burden at the scale at which resource-allocation decisions are made.

METHODS

The burden of T.b. rhodesiense was estimated during an outbreak of HAT in Serere, Uganda. We identified the unique characteristics affecting the burden of rhodesiense HAT such as age, severity, level of under-reporting and duration of hospitalisation, and use field data and empirical estimates of these to model the burden imposed by this and other important diseases in this study population. While we modelled DALYs using standard methods, we also modelled uncertainty of our parameter estimates through a simulation approach. We distinguish between early and late stage HAT morbidity, and used disability weightings appropriate for the T.b. rhodesiense form of HAT. We also use a model of under-reporting of HAT to estimate the contribution of un-reported mortality to the overall disease burden in this community, and estimate the cost-effectiveness of hospital-based HAT control.

RESULTS

Under-reporting accounts for 93% of the DALY estimate of rhodesiense HAT. The ratio of reported malaria cases to reported HAT cases in the same health unit was 133:1, however, the ratio of DALYs was 3:1. The age productive function curve had a close correspondence with the HAT case distribution, and HAT cases occupied more patient admission time in Serere during 1999 than all other infectious diseases other than malaria. The DALY estimate for HAT in Serere shows that the burden is much greater than might be expected from its relative incidence. Hospital based control in this setting appears to be highly cost-effective, highlighting the value of increasing coverage of therapy and reducing under-reporting.

CONCLUSION

We show the utility of calculating DALYs for neglected diseases at the local decision making level, and emphasise the importance of improved reporting systems for acquiring a better understanding of the burden of neglected zoonotic diseases.

An oral recombinant vaccine in dogs against Echinococcus granulosus, the causative agent of human hydatid disease: a pilot study

Dogs are the main source of human cystic echinococcosis. An oral vaccine would be an important contribution to control programs in endemic countries. We conducted two parallel experimental trials in Morocco and Tunisia of a new oral vaccine candidate against Echinococcus granulosus in 28 dogs. The vaccine was prepared using two recombinant proteins from adult worms, a tropomyosin (EgTrp) and a fibrillar protein similar to paramyosin (EgA31), cloned and expressed in a live attenuated strain of Salmonella enterica serovar typhimurium.

In each country, five dogs were vaccinated with the associated EgA31 and EgTrp; three dogs received only the vector Salmonella; and six dogs were used as different controls. The vaccinated dogs received two oral doses of the vaccine 21 d apart, and were challenged 20 d later with 75,000 living protoscoleces. The controls were challenged under the same conditions. All dogs were sacrificed 26–29 d postchallenge, before the appearance of eggs, for safety reasons.

We studied the histological responses to both the vaccine and control at the level of the duodenum, the natural localization of the cestode. Here we show a significant decrease of parasite burden in vaccinated dogs (70% to 80%) and a slower development rate in all remaining worms. The Salmonella vaccine EgA31-EgTrp demonstrated a high efficacy against E. granulosus promoting its potential role in reducing transmission to humans and animals.

In many countries in the world, livestock and humans are affected with hydatid disease, which is caused by the development, in the viscera, of the larval stage of the cestode Echinococcus granulosus. They become infected by ingesting the eggs of this parasite, which are passed in the feces of the dog—the host of the adult worm. Domestic dogs are key in the transmission to livestock and humans.

This disease remains a major economic and public health problem in affected countries. Because dogs are quickly reinfected, control programs in these locations include monthly anthelmintic deworming. These control measures, however, are burdensome for the owner, so they often fail. In contrast, vaccination can take place in control programs at different stages of the parasite life cycle. For example, currently an effective recombinant vaccine for sheep has been developed that should work indirectly to reduce infection in dogs, which tend to eat sheep offal. However, we propose that a recombinant oral vaccine given to the small number of dogs keeping the herd would decrease the number of Echinococcus granulosus adult worms and, consequently, the number of infective eggs. This measure would help reduce the contamination risk factors for humans and livestock, and would be cost-effective for the owners of the dogs.

The Global Burden of Disease assessments--WHO is responsible?

The Global Burden of Disease (GBD) concept has been used by the World Health Organization (WHO) for its reporting on health information for nearly 10 years. The GBD approach results in a single summary measure of morbidity, disability, and mortality, the so-called disability-adjusted life year (DALY). To ensure transparency and objectivity in the derivation of health information, WHO has been urged to use reference groups of external experts to estimate burden of disease. Under the leadership and coordination of WHO, expert groups have been appraising and abstracting burden of disease information. Examples include the Child Health Epidemiology Reference Group (CHERG), the Malaria Monitoring and Evaluation Reference Group (MERG), and the recently established Foodborne Disease Burden Epidemiology Reference Group (FERG). The structure and functioning of and lessons learnt by these groups are described in this paper. External WHO expert groups have provided independent scientific health information while operating under considerable differences in structure and functioning. Although it is not appropriate to devise a single "best practice" model, the common thread described by all groups is the necessity of WHO's leadership and coordination to ensure the provision and dissemination of health information that is to be globally accepted and valued.

Research approaches for improved pro-poor control of zoonoses

BACKGROUND

Developing countries face difficulties in sustainably utilizing tools to effectively implement control measures for zoonoses. This is mainly due to dispersed and heterogeneous smallholder livestock systems, predominance of informal markets, poor infrastructure and lack of resources to deliver information, interventions, and regulations. In addition, developing countries lack an evidence base for planning and targeting control efforts. Zoonotic infections are receiving more and more international attention as diseases of neglected and impoverished communities, at the intersection between livestock production, human health, and poverty.

OBJECTIVE

To review research innovations and trends that can help identify and test targeted control strategies for zoonoses tailored to poor communities, focusing particularly on Africa.

METHODS

Review of recommendations of relevant working groups and scientific literature.

RESULTS

New and innovative research approaches promise to better capture the impact of zoonoses from a societal perspective and the perspective of poor livestock owners through more comprehensive frameworks that consider benefits of the control of zoonoses to the public health, livestock, and private sectors. It is challenging to better assure food safety in informal markets. Risk-based approaches with participatory elements provide a framework in which stakeholders can decide an appropriate level of protection to balance the needs for safe food, cheap food, and pro-poor economic growth. Appropriate information for all stakeholders and capacity-building of national and regional authorities is an important element of this process. New diagnostic tools that are accurate and easily used in developing-country health centers and markets can assist in reporting of cases, detection of patients, and testing of control strategies.

CONCLUSIONS

A research agenda on zoonoses of the livestock sector should be interdisciplinary and participatory and include intersectoral collaborations, notably between the livestock and public health sectors.

Prevention and control of cystic echinococcosis

Human cystic echinococcosis (hydatid disease) continues to be a substantial cause of morbidity and mortality in many parts of the world. Elimination is difficult to obtain and it is estimated that, using current control options, achieving such a goal will take around 20 years of sustained efforts. Since the introduction of current (and past) hydatid control campaigns, there have been clear technological improvements made in the diagnosis and treatment of human and animal cystic echinococcosis, the diagnosis of canine echinococcosis, and the genetic characterisation of strains and vaccination against Echinococcus granulosus in animals. Incorporation of these new measures could increase the efficiency of hydatid control programmes, potentially reducing the time required to achieve effective prevention of disease transmission to as little as 5-10 years.

Ultrasonographic screening for cystic echinococcosis in sheep in Tunisia

Sheep from the areas of Fondouk-Jeddid, Bir Mchergua and El Fahs, located in the Northeast of Tunisia, were examined by ultrasonography between 2001 and 2004 in order to assess their infection with Echinococcus granulosus, the agent of hydatid disease, and to evaluate this method as an efficient aire for hydatid cysts. A total of 1039 sheep, aged between 1 and 14 years was examined. The highest prevalence was found in sheep aged more than 8 years. The least infected animals were aged between 1 and 2 years. All hydatid cysts detected by ultrasound were located in the liver. In all age-groups, the dead cysts were more numerous than viable cysts. Eighteen positive sheep were autopsied and a comparison between ultrasound and autopsy results was performed. The results showed a prevalence of about 40% for the three areas. Ultrasonography allowed the cysts, deep or superficial to localize in the central or left part in relation to the caudal vena cava of the animals. Consequently, all the cysts were not detected with this technique. This work shows that ultrasonography confirms the importance of ovine hydatid cyst in Tunisia and that its use as a mass screening approach for cystic echinococcosis in sheep could be helpful for the monitoring of this disease in a hydatid control program without great stress for the animals.

Reconsidering the underestimated burden caused by neglected tropical diseases

It is generally acknowledged that the burden caused by neglected tropical diseases needs to be reassessed. Not only are there several important diseases unaccounted for, but new information suggests they have a more substantial impact on health than initially thought. Looking at the tropical diseases as a group makes sense: they tend to cluster in the same poor populations and, to make progress with their control, they will have to be dealt with in an integrated manner. Measuring the effect of such integrated control is likely to reveal the real impact of tropical diseases on human health and wellbeing.