The global burden of neglected zoonotic diseases: current state of evidence

 

The majority of emerging infectious diseases are zoonoses, most of which are classified as “neglected”. By affecting both humans and animals, zoonoses pose a dual burden. The disability-adjusted life year (DALY) metric quantifies human health burden using mortality and morbidity. This review aims to describe and analyze the current state of evidence on the burden of neglected zoonotic diseases (NZDs) and start a discussion on the current understanding of the global burden of NZDs. We identified 26 priority NZDs through consulting the CDC One Health Zoonotic Disease Prioritization Exercise, the Joint External Evaluation reports, and the WHO roadmap for NTDs. A systematic review of global and national burden of disease (BoD) studies for these priority NZDs was conducted using pre-selected databases. Data on diseases, location and DALYs were extracted for each eligible study. A total of 1887 records were screened, resulting in 72 eligible studies (58 national or sub-national, 12 global, and 2 regional studies). The highest number of BoD studies was found for non-typhoidal salmonellosis (23), whereas no estimates were found for West Nile, Marburg and Lassa fever. Geographically, the highest number of studies were found in the Netherlands (11), China (5) and Iran (4). The number of BoD studies retrieved mismatched the perceived importance in national prioritization exercises. For example, anthrax was considered a priority NZD in 73 countries, but only one national estimate was retrieved. By summing the available global estimates, these diseases would cause at least 10 million DALYs in total. The burden of NZDs at the global level remains scattered, and trends were challenging to identify. There are several priority NZDs for which no burden estimates exist, and the number of BoD studies does not reflect national disease priorities. To have complete and consistent estimates of the global burden of NZDs, these diseases should be integrated into larger global BoD initiatives.

Key messages

• There is a mismatched between the estimated retrieved in the search and the perception of the importance of these disease. This amplify the need for a comprehensive program.

• No complete list of zoonoses exist, and the definition used is vague. A stricter definition of zoonoses and what defines them will help provide a clear view of dealing with and controlling them.

Methodological choices in brucellosis burden of disease assessments: A systematic review

Background

Foodborne and zoonotic diseases such as brucellosis present many challenges to public health and economic welfare. Increasingly, researchers and public health institutes use disability-adjusted life years (DALYs) to generate a comprehensive comparison of the population health impact of these conditions. DALY calculations entail several methodological choices and assumptions, with data gaps and uncertainties to accommodate. The following review identifies existing brucellosis burden studies and analyses their methodological choices and assumptions.

Methods/Findings

A systematic search for brucellosis burden calculations was conducted in pre-selected international and grey literature databases. Using a standardized reporting framework, we evaluated each estimate on a variety of key methodological assumptions necessary to compute a DALY. One study reported estimates at the global level, the rest (13) at national or subnational. Most studies retrieved brucellosis epidemiological data from administrative registries. Incidence data were often estimated based on laboratory-confirmed tests. Not all studies included mortality estimates (YLLs) in their assessments due to the lack of data or the assumption that brucellosis is not a fatal disease. Only two studies used a model with variable health states and corresponding disability weights. The rest used a simplified singular health state approach. Wide variation was seen in the duration chosen for brucellosis, ranging from 2 weeks to 4.5 years, irrespective of whether a chronic state was included.

Conclusions

Available brucellosis burden assessments vary widely in their methodology and assumptions. Further research is needed to characterize better the total clinical course of brucellosis and estimate case-fatality rate. In addition, reporting of methodological choices should be improved to enhance transparency and comparability of estimates. These steps will increase the value of these estimates for policymakers.

Key messages

• Inconsistencies in reporting methods and assumptions are found, which hinder transparency and understanding of the methodological choices and the reuse of estimates for prioritization purposes.

• Thus, there is a need for a more standardized reporting system for DALY estimates, which could resemble a checklist that reports the methodological choices and assumptions.

Global Burden of Animal Diseases: a novel approach to understanding and managing disease in livestock and aquaculture

Investments in animal health and Veterinary Services can have a measurable impact on the health of people and the environment. These investments require a baseline metric that describes the burden of animal health and welfare in order to justify and prioritise resource allocation and from which to measure the impact of interventions. This paper is part of a process of scientific enquiry in which problems are identified and solutions sought in an inclusive way. It poses the broad question: what should a system to measure the animal disease burden on society look like and what value would it add? Moreover, it aims to do this in such a way as to be accessible by a wide audience, who are encouraged to engage in this debate. Given that farmed animals, including those raised by poor smallholders, are an economic entity, this system should be based on economic principles. These poor farmers are negatively impacted by disparities in animal health technology, which can be addressed through a mixture of supply-led and demand-driven interventions, reinforcing the relevance of targeted financial support from government and non-governmental organisations. The Global Burden of Animal Diseases (GBADs) Programme will glean existing data to measure animal health losses within carefully characterised production systems. Consistent and transparent attribution of animal health losses will enable meaningful comparisons of the animal disease burden to be made between diseases, production systems and countries, and will show how it is apportioned by people's socio-economic status and gender. The GBADs Programme will produce a cloud-based knowledge engine and data portal, through which users will access burden metrics and associated visualisations, support for decisionmaking in the form of future animal health scenarios, and the outputs of wider economic modelling. The vision of GBADs, strengthening the food system for the benefit of society and the environment, is an example of One Health thinking in action.

Redistribution of halothane and sevoflurane under simulated conditions of acute airway obstruction

Forty patients having surgery requiring muscle paralysis and tracheal intubation were randomly allocated to receive either halothane (n = 20) or sevoflurane (n = 20). Following intravenous anaesthesia and tracheal intubation, inhalation induction of anaesthesia was simulated. After attaining an end-tidal anaesthetic concentration of 2 MAC for the respective agent, the airway was obstructed for 3 min. The end-tidal anaesthetic concentration was measured for the first three breaths following the period of airway obstruction. The decrease in alveolar concentration of sevoflurane following 3 min of airway obstruction was found to be significantly greater than that of halothane. We conclude that even if the airway obstructs completely during inhalational induction of general anaesthesia, awakening would be faster with sevoflurane than with halothane.

Mechanical bridge to recovery in fulminant myocarditis

A patient with acute fulminant lymphocytic myocarditis and cardiogenic shock was successfully treated by mechanical off loading of the left ventricle. A nonpulsatile left-heart bypass was undertaken with an implantable centrifugal blood pump. Careful weaning resulted in device removal on the seventh day. Left and right ventricular function is sustained at 7 months. Widespread application of this method depends on the availability of an inexpensive user friendly blood pump, appropriate weaning protocols and emerging strategies to promote sustainable myocardial recovery.

Jarvik 2000 heart: potential for bridge to myocyte recovery

BACKGROUND

Mechanical bridge to left ventricular recovery is an emerging strategy for the treatment of heart failure. We sought to validate the use of a new intracardiac axial flow impeller pump for this purpose.

METHODS AND RESULTS

The Jarvik 2000 Heart was implanted into 30 sheep to ascertain mechanical reliability, biocompatibility, and hemodynamic function. We attempted but failed to anticoagulate with warfarin. Elective explants with survival were performed in 3 animals to simulate bridge to recovery. Extensive autopsy studies were performed in all other animals. At speeds between 8000 and 12 000 rpm the device pumped up to 8 L/min, captured all mitral flow, and augmented cardiac output with elevation of mean arterial pressure. The pump was silent and hemolysis negligible. Nonpulsatile flow did not adversely affect neurological or renal function. Device removal proved straightforward and safe. A fractured inflow bearing occurred in 1 early model. There were no other pump failures, but power interruption occurred when the sheep chewed the cables or head-butted the percutaneous pedestal. At autopsy, there was no thromboembolism or primary thrombus formation in any device. Pump occlusion occurred in 2 sheep with bacterial endocarditis. One electively explanted pump, previously switched off for 5 months, had no thrombus in the device or vascular graft.

CONCLUSIONS

The Jarvik 2000 Heart is a major advance in blood-pump technology and increases the scope of mechanical circulatory support. Reliability and ease of removal favor its use for bridge to myocyte recovery, as well as for bridge to transplantation or long-term support.

Cardiovascular effects of concomitant administration of isoflurane and nicorandil in dogs

Nicorandil, a new KATP channel opener, is used in clinical practice for anti-anginal therapy. It exhibits vasodilator properties as does the halogenated anaesthetic isoflurane. We have examined the cardiovascular effects of increasing concentrations of isoflurane after administration of nicorandil in 10 adult beagle dogs anaesthetized with thiopental and whose lungs were ventilated mechanically. During surgery, anaesthesia was maintained with 1.0-1.5% isoflurane. A left thoracotomy was performed and the heart suspended in a pericardial cradle. Monitoring included: ECG; aortic, left ventricular, arterial, central venous and pulmonary artery pressures; cardiac output; coronary flow; and segmental length in the apical region. After surgery, isoflurane anaesthesia was set at an end-tidal concentration of 1.05% (1 MAC) and measurements obtained; these were repeated with 1.4%, 1.75%, 2.1% and 1.05% isoflurane concentrations after appropriate stabilization periods. Nicorandil (100 micrograms kg-1 bolus, 25 micrograms kg-1 min-1 infusion) was begun and a second dose-response study of isoflurane was obtained as before. Blood samples were obtained for measurement of concentrations of nicorandil. Systolic ventricular function was assessed by systolic shortening (%SS) and preload recruitable stroke work (PRSW). Increasing isoflurane concentration produced decreases in heart rate, systolic pressure, cardiac output, %SS and PRSW. Nicorandil produced a slight decrease in systolic arterial pressure (10 and 15 mm Hg after 1.05% and 2.05% isoflurane) and a slight increase in heart rate (10 and 5 beat min-1 after 1.05% and 2.05% isoflurane). Preload, assessed by end-diastolic length, decreased. Coronary blood flow increased with infusion of nicorandil. Left ventricular function was not affected by infusion of nicorandil. We conclude that nicorandil has only minor vaso/venodilatory effects in the presence of isoflurane. Ventricular function was not altered by infusion of nicorandil.

LVAD power delivery: a percutaneous approach to avoid infection

BACKGROUND

Driveline infection limits the event-free survival of patients with a left ventricular assist device. With the evolving prospect of improved left ventricular assist devices in the bridge-to-transplantation or recovery setting, we sought to reduce the risk of driveline complications.

METHODS

As part of the Oxford Jarvik 2000 research program, we developed a carbon and then titanium pedestal to transmit the electric wires through the skin. In a sheep model, the pedestal was brought out through the skin of the shoulder (n = 10) or the scalp (n = 9) with underlying fixation to the skull. Exit wounds were carefully inspected for healing and infection. Power cable durability tests were performed in 6 additional animals without an implanted pump.

RESULTS

The cumulative observation period was 1,491 days (mean time, 78 days; range, 14 days to 198 days). There was no difference in observation period between the two groups. Infection (n = 2) and impaired healing (n = 5) occurred in the mobile tissues at the shoulder. Skull-mounted pedestals were free from infection or healing problems. The electric cables were not interrupted by repeated neck flexion (cumulative observation period, 588 days). The carbon pedestal was replaced by a titanium pedestal when the head butting of the sheep fractured the carbon.

CONCLUSIONS

The combination of rigid fixation and highly vascular scalp skin reduces the risk of percutaneous driveline infection and may solve an important outstanding problem in use of left ventricular assist devices.

The Jarvik 2000 Oxford system: increasing the scope of mechanical circulatory support

METHODS

We developed a system for mechanical circulatory support based on the Jarvik 2000 intraventricular axial flow impeller pump (Jarvik Research, Inc., New York, N.Y.) and percutaneous electric power. The adult pump provides flow at a rate up to 10 L/min with an energy requirement of 7 to 10 watts. The device was implanted into the apex of the left ventricle through a left thoracotomy without cardiopulmonary bypass. A Dacron graft conveyed blood to the descending thoracic aorta. In patients, we will use a skull-mounted carbon pedestal to transmit fine electric wires through the scalp skin. Being highly vascular, the scalp skin is resistant to infection.

RESULTS

We tested 16 adult systems and one pediatric system in 17 adult ewes weighing between 60 and 90 kg. Five died of perioperative complications. Twelve survived between 3 and 198 days (mean 44 days) with a functioning device. None of the sheep could receive adequate anticoagulation with warfarin (INR 1.0 to 1.5). Acute thrombotic occlusion occurred after a 3-hour power loss in one device (46 days) but was cleared with streptokinase. In a second animal with endocarditis, the pump inflow became occluded with vegetations. No other device-related problems or important hemolysis developed despite pump speeds between 10,000 and 18,000 rpm. Renal function remained normal in all animals. Autopsy studies showed no pannus ingrowth at the device inflow despite the restrictive left ventricular cavity size. No sign of thromboembolism could be detected in the brains or kidneys.

CONCLUSION

Our findings indicate the Jarvik 2000 Oxford System to be a safe and effective circulatory assist device. Potential uses include permanent circulatory support, bridge to transplantation, or bridge to myocardial recovery in acute or chronic left ventricular failure.

Beneficial effect of concomitant administration of isoflurane and nicorandil

In common with halogenated anaesthetics, nicorandil, a new KATP channel opener, has been shown to have cardioprotective and vasodilator effects. Recent studies have also suggested that the vasodilator and protective effects of halogenated anaesthetics are mediated partly via KATP channel opening. This study examined the effects of concurrent administration of nicorandil and isoflurane on haemodynamic state and ventricular function before, during and after 15 min of ischaemia. We studied left ventricular function in 40 anaesthetized rabbits using ultrasonomicrometry. Measurements were obtained before, during and after 15 min of regional ischaemia. Regional ventricular function was assessed in terms of systolic shortening (SS%) and preload recruitable work area (PRWA, the area beneath the regional stroke work vs end-diastolic length relationship) during reperfusion. Four groups were studied: group F (n = 10) received a bolus dose of fentanyl 100 micrograms kg-1 and then 400 micrograms kg-1 h-1 throughout; group 1 (n = 10) received 2.05% end-tidal concentration of isoflurane (1 MAC); group FN (n = 10) received fentanyl, a bolus does of nicorandil 100 micrograms kg-1 and then 25 micrograms kg-1 min-1, 15 min before occlusion; and group IN (n = 10) received isoflurane and nicorandil. Isoflurane decreased left ventricular systolic pressure and ventricular contractility (+dP/dtmax, slope of preload recruitable stroke work, and SS%). Nicorandil increased -dP/dtmax in group FN. Post-ischaemic regional left ventricular contractility in group I did not differ from that in group F, however, groups receiving nicorandil recovered to a greater extent. Group IN showed better recovery compared with all other groups when ventricular contractility was assessed by PRWA normalized to pre-occlusion values (mean 99.3 (SEM 10.5)% vs 73.4 (7.5)%, 50.2 (5.8)% and 52.4 (3.7)% at 120 min reperfusion in groups FN, I and F, respectively). Tissue ATP and lactate contents did not differ between groups. We conclude that concurrent administration of nicorandil and isoflurane enhanced post-ischaemic recovery compared with isoflurane anaesthesia or nicorandil and fentanyl administration.

Characterization of a mutated p53 exhibiting a cell cycle-related nuclear translocation

We studied the p53 expression in the F4NW0 cell line. We found that this mutated p53 has a deletion of eight amino acids, between the conserved domains IV and V. Only one of the two alleles is expressed. It contains a single base mutation, which seems to promote the use of a cryptic splicing acceptor site, resulting in the observed deletion. The protein shows a cell cycle-dependent nuclear translocation: in G(1), it is exclusively cytoplasmic, and during the G(1)/S transition, it translocates into the nucleus. Nevertheless, different antibodies assayed revealed different patterns of localization.

Transactivation of the p53 oncogene by E1a gene products

Infection of quiescent rat kidney cells with human adenovirus is shown to transcriptionally stimulate (transactivate) the p53 oncogene. The increased transcription results in an accumulation of p53-specific mRNA in parallel with an increase in p53 protein levels, although there is a considerable delay between transcriptional activation and the detection of stable p53 mRNA and protein. The induction of p53 is detectable with two monoclonal antibodies recognizing different epitopes. The induction of p53 by adenovirus is delayed compared to induction by serum, and it occurs after the onset of adenovirus-induced cellular DNA replication. Thus, adenovirus-induced DNA replication bypasses a G0/G1 control point. Experiments with hydroxyurea show that p53 activation does not require continued cell cycling and thus is likely to be a direct consequence of viral gene expression. Finally, the induction of p53 is shown to be dependent on expression of the 289-residue product encoded by the viral E1a gene.

Simultaneous isolation of DNA, RNA, and antigenic protein exhibiting kinase activity from small tumor samples using guanidine isothiocyanate

Correlative studies of genes and their expression in human tumors are often hampered by the small sample size and the need to use differing and incompatible techniques to obtain DNA, RNA, and protein. We describe an extension of the established guanidine isothiocyanate method for isolation of DNA and RNA which allows the simultaneous isolation of total cellular protein. The protein obtained by this method (from solid tumors and cell lines) was comparable to protein extracted by a standard detergent solubilization method. Antigenicity was retained as demonstrated by Western blotting for epidermal growth factor receptor and actin and by immunoprecipitation of p53. Kinase activity was similar in proteins extracted by the two methods. It seems probable that most monomeric proteins can be obtained in a form suitable for Western analysis and immunoprecipitation and that these may also retain some functional activity.

Hydrocortisone stimulation of human mammary epithelial cells

Rapid proliferation of mammary epithelial cells derived from biopsy specimens of human fibroadenomas was observed when medium was supplemented with ten percent fetal bovine serum and hydrocortisone (5 microgram per ml-1). Hydrocortisone in combination with FBS also led to a 2.5-fold increase in cell cluster attachment and subsequent colony formation. A similar effect was not observed with human serum. In contrast to fibroblast cell systems, insulin did not significantly alter cell growth. The results show that a mitogenic response to glucocorticoids by mammary epithelium may depend on the presence of factors in sera.

Effect of serum on cells cultured from human mammary tumors

Clusters of cells derived from biopsy specimens of human mammary ductal carcinomas form two morphologically distinct epithelial colonies in culture, designated as E and E'. The proportion of E' cell clusters that attached and formed colonies ranged from 0.3 to 13.0% with different tumors. Attachment was independent of tumor grade. Microscopic observations revealed that the survival of E' cell colonies was limited to approximately 10 days with rapid cell degeneration commencing about 7 days. A comparison of sera showed that colony formation by cells from malignant tumors during the 1st week of culture was maximum in the presence of fetal bovine serum. Human serum alone was 70 to 100% less effective in promoting E' colonies. The most significant finding was that human serum from normal donors inhibited E' colony development in the presence of FBS. Although human serum was less effective than FBS in promoting colony formation by clusters of E cells, an inhibition was not observed. Inhibitory activity could not be attributed to either antagonistic hormones or the source of human serum. These results demonstrate that normal human serum contains a factor(s) that exhibits an inhibitory activity specific for human epithelial cells (E') derived from malignant tumors.