More accurate insight into the incidence of human rabies in developing countries through validated laboratory techniques

Recent updates on laboratory diagnosis of rabies

Rabies is a lethal viral disease transmitted through the bite of rabid animals. India has a high burden of rabies, contributing to a significant proportion of the global deaths. However, under-reporting of the disease is prevalent due to lack of laboratory confirmation. Laboratory diagnosis of rabies plays a crucial role in differentiating the disease from clinical mimics, initiation of appropriate care, implementing infection control measures and informing disease surveillance. This review provides an overview of the recent advancements in laboratory diagnosis of rabies, aimed at updating physicians involved in diagnosis and management of rabies cases in India.

Case of human rabies despite post-exposure prophylaxis (PEP) and complete recovery after intrathecal rabies immunoglobulin (RIG)

Rabies, a fatal viral zoonotic disease, has become a public health concern in Sarawak, Malaysia. Despite pre-exposure and post-exposure prophylaxis being available, there has been limited progress in developing treatments for rabies, emphasising the pressing need for productive solutions. We present a laboratory-confirmed human rabies case in which the patient survived without neurological sequelae after receiving intrathecal rabies immunoglobulin.

Soares Magalhães R, Weese JS, Ahmed NO, Rupprecht CE, Clark NJ. Modelling modifiable factors associated with the probability of human rabies deaths among self-reported victims of dog bites in Abuja, Nigeria

Canine-mediated rabies kills tens of thousands of people annually in lesser-developed communities of Asia, Africa, and the Americas, primarily through bites from infected dogs. Multiple rabies outbreaks have been associated with human deaths in Nigeria. However, the lack of quality data on human rabies hinders advocacy and resource allocation for effective prevention and control. We obtained 20 years of dog bite surveillance data across 19 major hospitals in Abuja, incorporating modifiable and environmental covariates. To overcome the challenge of missing information, we used a Bayesian approach with expert-solicited prior information to jointly model missing covariate data and the additive effects of the covariates on the predicted probability of human death after rabies virus exposure. Only 1155 cases of dog bites were recorded throughout the study period, out of which 4.2% (N = 49) died of rabies. The odds for risk of human death were predicted to decrease among individuals who were bitten by owned dogs compared to those bitten by free-roaming dogs. Similarly, there was a predicted decrease in the probability of human death among victims bitten by vaccinated dogs compared to those bitten by unvaccinated dogs. The odds for the risk of human death after bitten individuals received rabies prophylaxis were predicted to decrease compared to no prophylaxis. We demonstrate the practical application of a regularised Bayesian approach to model sparse dog bite surveillance data to uncover risk factors for human rabies, with broader applications in other endemic rabies settings with similar profiles. The low reporting observed in this study underscores the need for community engagement and investment in surveillance to increase data availability. Better data on bite cases will help to estimate the burden of rabies in Nigeria and would be important to plan effective prevention and control of this disease.

From Field Tests to Molecular Tools-Evaluating Diagnostic Tests to Improve Rabies Surveillance in Namibia

Rabies is endemic in Namibia and is present both in wildlife carnivores and domestic free-roaming dogs. The disease thus represents a challenge for public human and veterinary disease control. Namibia has implemented a national strategic plan to control rabies and the country's activities are supported by international organizations. To this end, rabies diagnosis at the Central Veterinary Laboratory (CVL) was improved in the frame of a World Organization for Animal Health (WOAH) laboratory twinning program: from practical sampling techniques and the use of lateral flow devices to a novel universal and discriminatory quantitative real-time Reverse transcription polymerase chain reaction (RT-qPCR), which easily identify dog-associated rabies viruses. The procedures applied and the results can be used as a template to improve rabies laboratory diagnosis.

Dual-Mode Immunosensor for Electrochemiluminescence Resonance Energy Transfer and Electrochemical Detection of Rabies Virus Glycoprotein Based on Ru(bpy)32+-Loaded Dendritic Mesoporous Silica Nanoparticles

Rabies is a serious zoonotic disease in almost all warm-blooded animals and causes fatal encephalitis. The detection of rabies virus (RABV) is critical and remains a significant challenge. Herein, an electrochemiluminescence resonance energy transfer (ECL-RET) and electrochemical (EC) dual-mode immunosensor was developed for highly sensitive detection of RABV glycoprotein. Dendritic mesoporous silica nanoparticles (DMSNs) were employed to load Ru(bpy)₃²⁺ and to obtain ECL probes (Ru@DMSNs). Ru@DMSNs were decorated on the electrode surface, followed by the modification of the RABV antibody (Ab₁). RABV was specifically recognized and captured by Ab₁, causing the decline of the ECL signal due to the obstruction of electron transfer. Additionally, manganese oxide nanoparticles (MnO_x) modified with Ab₂ can further quench the ECL signal of Ru@DMSNs via the RET between Ru@DMSNs and MnO_x. Meanwhile, MnO_x can catalyze the oxidation of o-phenylenediamine (o-PD), generating a significant differential pulse voltammetry (DPV) signal as a second signal to monitor RABV glycoprotein concentration. Consequently, an immunosensor was developed to achieve dual-signal detection of RABV and improve reliability. Under the optimal conditions, detection ranges of 0.10 pg·mL^-1 to 10 ng·mL^-1 for ECL (with an 88 fg·mL^-1 detection limit) and 1 pg·mL^-1 to 2 ng·mL^-1 for EC (with a 0.1 pg·mL^-1 detection limit) were obtained for RABV detection. The reliability of this immunoassay was validated by eight brain tissue samples. The results were found to be compatible with the results of the real-time reverse transcription-polymerase chain reaction (RT-PCR) assay, indicating the potential applicability of this method for RABV diagnosis.

Dog rabies control in West and Central Africa: A review

Rabies is a neglected but preventable zoonotic disease that predominantly affects the most vulnerable populations living in remote rural areas of resource-limited countries. To date, every country on the African mainland is considered endemic for dog-mediated rabies with an estimated 21'500 human rabies deaths occurring each year. In 2018, the United Against Rabies collaboration launched the Global Strategic Plan to end human deaths from dog-mediated rabies by 2030. The epidemiology of rabies from most Western and Central African countries remains poorly defined, making it difficult to assess the overall rabies situation and progress towards the 2030 goal. In this review, we attempt to provide an overview of the current rabies situation in 22 West and Central African countries based on published scientific literature and information obtained from rabies focal points. To this end, information was collected on i) established surveillance, ii) diagnostic capacity, iii) post-exposure prophylaxis (PEP) availability and coverage, iv) dog population estimates, v) dog vaccination campaigns, vi) animal and human health communication (One Health), vii) molecular studies, viii) Knowledge, Attitude and Practices (KAP), ix) cost estimates and x) national control strategies. Although rabies is a notifiable disease in the majority of the studied countries, national surveillance systems do not adequately capture the disease. A general lack of rabies diagnostic capacity has an additional negative impact on rabies surveillance and attempts to estimate rabies burden. Recurrent shortages of human rabies vaccine are reported by all of the countries, with vaccine availability usually limited to major urban centers but no country has yet adopted the new WHO-recommended 1-week intradermal vaccination regimen. Most countries carry out subsidized mass dog vaccination campaigns on World Rabies Day. Such activities are indispensable to keep rabies in the public consciousness but are not of the scale and intensity that is required to eliminate rabies from the dog population. Countries will need to scale up the intensity of their campaigns, if they are to progress towards the 2030 goal. But more than half of the countries do not yet have reliable figures on their dog populations. Only two countries reached stage 2 on the Stepwise Approach towards Rabies Elimination ladder - indicating that their national governments have truly prioritized rabies elimination and are thus providing the necessary support and political buy-in required to achieve success. In summary, the sub-region of West and Central Africa seems to be divided into countries which have accepted the challenge to eliminate rabies with governments committed to pushing forward rabies elimination, while other countries have achieved some progress, but elimination efforts remain stuck due to lacking government commitment and financial constraints. The possibility to meet the 2030 goal without international solidarity is low, because more than two-thirds of the countries rank in the low human development group (HDI ≤ 152). Leading countries should act as role models, sharing their experiences and capacities so that no country is left behind. Unified and with international support it is possible to reach the common goal of zero human rabies deaths by 2030.

Increasing rabies data availability: The example of a One Health research project in Chad, Côte d'Ivoire and Mali

Rabies is a fatal but preventable disease that remains notoriously underreported. Weak data availability hampers advocacy, constitutes a barrier to resource allocation and inhibits effective prevention and control. To gain better insight into the global rabies burden and human vaccine demand several studies were funded through the Vaccine Alliance (GAVI) learning agenda. With the help of this funding, Swiss TPH and local in country partner organizations implemented a One Health research project in Chad, Côte d'Ivoire and Mali to collect data at household, public health facility and veterinary level. This paper describes the implementation of this research project and evaluates its success on amount of information gained, achieved capacity building, impact on knowledge creation and influence on national and international policies. The project was based on the One Health concept and guided by the principles of transboundary research partnerships formulated by the Swiss Academy of Sciences. Data was collected on bite incidents and health seeking from over 24'000 households, on access to treatment of over 8'800 bite cases registered in public health facilities and on the status of over 1'800 rabies suspect animals. Selected country specific datasets have contributed to more than 10 scientific articles so far. On the international level, the multi-level data collection provided a unique set of indicators to inform, along with results from other studies, new WHO rabies immunization recommendations and a vaccine investment case scenario to prevent human rabies. New rabies burden estimates based on the data gathered are published for Mali and will be modelled for the whole West and Central African region. On the national level, the project facilitated communication between animal health and human health workers catalyzing creation of local and national committees and formulation of national action plans for Mali and Côte D'Ivoire. Major challenges arose from lack of data collection and documentation experience of human health and veterinary workers and weak infrastructural capacities of the veterinary and human health systems of the project countries. Through adherence to the principles of transboundary research partnerships, project team members acquired valuable research and networking skills despite language barriers, enabling them to play key roles in the future agenda towards national, regional and global canine rabies elimination. Project external collaborations with local public institutions was facilitated through long-term local partnerships. Both factors enabled success in project implementation and outcomes by identifying and mitigating risks in advance, resolving challenges amiably and enabling mutual knowledge creation as a fructuous ground for sustained commitment. Lack of immediate follow-up funding did not allow to maintain activities beyond the project timeframe. However, the national and international policy changes triggered, as well as the strengthened local disease control and research capacities provides sustainable basis for the elimination of dog transmitted human rabies.

Multi-annual performance evaluation of laboratories in post-mortem diagnosis of animal rabies: Which techniques lead to the most reliable results in practice?

Rabies diagnosis proficiency tests on animal specimens using four techniques (FAT, RTCIT, conventional RT-PCR and real-time RT-PCR) were organised over 10 years (2009–2019). Seventy-three laboratories, of which 59% were from Europe, took part. As the panels were prepared with experimentally-infected samples, the error rate of laboratories on positive and negative samples was accurately estimated. Based on fitted values produced by mixed modelling including the variable “laboratory” as a random variable to take into account the longitudinal design of our dataset, the technique that provided the most concordant results was conventional RT-PCR (99.3%; 95% CI 99.0–99.6), closely followed by FAT (99.1%; 95% CI 98.7–99.4), real-time RT-PCR (98.7%; 95% CI 98.1–99.3) and then RTCIT (96.8%; 95% CI 95.8–97.7). We also found that conventional RT-PCR provided a better diagnostic sensitivity level (99.3% ±4.4%) than FAT (98.7% ±1.6%), real-time RT-PCR (97.9% ±0.8%) and RTCIT (95.3% ±5.1%). Regarding diagnostic specificity, RTCIT was the most specific technique (96.4% ±3.9%) followed closely by FAT (95.6% ±3.8%), real-time RT-PCR (95.0% ±1.8%) and conventional RT-PCR (92.9% ±0.5%). Due to multiple testing of the samples with different techniques, the overall diagnostic conclusion was also evaluated, and found to reach an inter-laboratory concordance level of 99.3%. The concordance for diagnostic sensitivity was 99.6% ±2.0% and for diagnostic specificity, 98.0% ±8.5%. Molecular biology techniques were, however, found to be less specific than expected. The potential reasons for such findings are discussed herein. The regular organisation of performance tests has contributed to an increase in the performance of participating laboratories over time, demonstrating the benefits of such testing. Maintaining a high-quality rabies diagnosis capability on a global scale is key to achieving the goal of eliminating dog-mediated human rabies deaths. The regular organisation of exercises on each continent using selected local strains to be tested according to the local epidemiological situation is one factor that could help increase reliable diagnosis worldwide. Rabies diagnosis capabilities could indeed be enhanced by providing adequate and sustainable proficiency testing on a large scale and in the long term

This study shares the rabies diagnosis proficiency test results of 73 laboratories on animal specimens using four techniques (FAT, RTCIT, conventional RT-PCR and real-time RT-PCR) organised over a 10-year period. This long-term exercise allowed us to compute accurate sensitivity and specificity values for the rabies diagnosis test for a large panel of laboratories. Conventional RT-PCR provided a better diagnostic sensitivity level than FAT, real-time RT-PCR and RTCIT. Regarding diagnostic specificity, RTCIT was the most specific technique followed closely by FAT, real-time RT-PCR and conventional RT-PCR. The specificity of molecular biology techniques was found to be lower than expected. The potential reasons for such findings are discussed herein. The regular organisation of performance tests has contributed to an increase in the performance of participating laboratories over time, demonstrating the likely benefits of such testing.

A recombinase polymerase amplification assay for rapid detection of rabies virus

Rabies is a generally fatal encephalitis caused by a negative-sense single-stranded RNA lyssavirus transmitted to humans mainly from dog bite. Despite the recommendation by WHO and OIE to use the direct immunofluorescence test as standard method, molecular diagnostic assays like reverse transcription quantitative polymerase chain reaction (RT-qPCR) are increasing as a confirmatory method. However, both technologies are inaccessible in resource-limited settings. Moreover, the available point-of-need molecular assay is of poor detection limit for African strains. Herein, we developed a reverse transcription recombinase polymerase amplification (RT-RPA) assay as potential point-of-need diagnostic tool for rapid detection of various strains of rabies virus including locally isolated African strains. The sensitivity and specificity of the method was evaluated using a molecular RNA standard and different Rabies-related viruses belonging to the Rhabdoviridea family, respectively. The RABV-RPA performances were evaluated on isolates representative of the existing diversity and viral dilutions spiked in non-neural clinical specimen. The results were compared with RT-qPCR as a gold standard. The RABV-RPA detected down to 4 RNA molecules per reaction in 95% of the cases in less than 10 min. The RABV-RPA assay is highly specific as various RABV isolates were identified, but no amplification was observed for other member of the Rhabdoviridea family. The sample background did not affect the performance of the RABV-RPA as down to 11 RNA molecules were identified, which is similar to the RT-qPCR results. Our developed assay is suitable for use in low-resource settings as a promising alternative tool for ante-mortem rabies diagnosis in humans for facilitating timely control decisions.

Human rabies in China: evidence-based suggestions for improved case detection and data gathering

Background

China still suffers heavily from rabies, although reported human cases continue to decrease year over year. There are far fewer laboratory-confirmed human cases than clinically diagnosed cases, which is a big problem that needs to be addressed. In this report, we summarize analyses of all specimens from human cases tested in our laboratory over the past 15 years, in order to promote laboratory diagnosis of rabies.

Methods

From 2005 to 2019, a total of 271 samples from 164 suspected rabies cases were collected from local hospitals by the local Centers for Disease Control and Prevention (CDCs) in China. Saliva, cerebrospinal fluid (CSF), serum (blood) and urine were collected for ante-mortem diagnosis, and brain tissue, neck skin tissue and cornea were collected for post-mortem diagnosis. All of the specimens were tested by reverse transcription-polymerase chain reaction (RT-PCR), and brain tissues were also tested using fluorescent antibody test (FAT). The number of positive test results obtained using different fluids or tissues, and at different stages of the disease, were compared using a chi-square test and a more effective sampling program is recommended.

Results

As the national reference laboratory for rabies surveillance in China, our laboratory has tested 271 samples from 164 suspected rabies cases collected by local CDCs since 2005. We found that saliva gave the highest number of positive test results (32%), compared with CSF and other fluids. We also found that serum or blood specimens collected in the last 3 days of life can test positive by RT-PCR.

Conclusions

Serum or blood samples collected in the last 3 days of a patient’s life can be used to measure viral RNA, which means that serum samples, as well as saliva and CSF, can be used to detect viral RNA for anti-mortem diagnosis of rabies. Because of our findings, we have modified our “National Surveillance Project for Human Rabies”, by adding the collection and testing of serum samples from the end of the survival period. This will improve our national surveillance and laboratory diagnosis of human rabies.

Dried blood spot cards: A reliable sampling method to detect human antibodies against rabies virus

Background

Although preventable by vaccination for more than a century, rabies virus still causes numerous fatalities every year. To determine antibody levels in humans, blood collected with a finger prick and applied on dried blood spot (DBS) cards is an alternative for venipuncture. The use of DBS is specifically valuable in remote areas, as it is easy to perform, store and transport. Therefore, the technique is frequently used for epidemiological studies of tropical diseases. Up to present, determination of rabies virus antibody levels on human DBS has not been validated.

Methodology/Principal findings

We evaluated the use of human DBS for rabies serology and analyzed 99 pre- or post-vaccination serum and DBS samples with a fluorescent antibody virus neutralization test (FAVNt), which is the gold standard to detect protective antibody levels, and a Bio-Rad Platelia Rabies II ELISA. Sensitivity and specificity of DBS eluates tested with the FAVNt were 97% and 92%, respectively and 87% and 96% when tested with the Platelia-II ELISA. Antibody levels measured in serum with the FAVNt, correlated best with antibody levels measured in DBS with the FAVNt (R = 0.88).

Conclusions/Significance

This is the first study that applies DBS for reliable detection of human antibodies against rabies virus. Both the FAVNt and Platelia-II ELISA demonstrate an acceptable performance on DBS, providing opportunities for rabies serology in remote areas. This technique could drastically ease studies evaluating (novel) rabies vaccination strategies and monitoring persisting immunity in humans at risk, living in rabies endemic regions.

Rabies is a nearly 100% fatal disease in humans. However, available vaccines are effective in preventing rabies infection. To investigate if a person is protected against rabies, rabies virus neutralizing antibody levels in the blood are determined. The World Health Organization defines protective immunity as a rabies virus antibody concentration of at least 0.5 IU/ml detected in serum using a virus neutralization test. Yet, in remote areas serum may be rather difficult to collect, process and transport. Whole blood collected with a finger prick and applied on filter paper cards, also known as dried blood spots (DBS), are an easier alternative. This collection method is frequently used for serology of several tropical infectious diseases, but never studied for rabies serology in humans. Therefore, we compared antibody levels measured in serum with those measured in DBS eluates, using the gold standard FAVNt and related it to another commonly used test for human rabies serology, the Platelia-II ELISA. We found that both assays had a good performance on DBS eluates. The reported high specificities provide confidence that unprotected individuals will rarely be missed. Therefore, the DBS is a promising sampling technique for evaluations of vaccination strategies and monitoring persisting immunity after vaccination in populations at risk for rabies.

Burden of rabies in Mali

Rabies is the most dreaded neglected zoonosis worldwide. It affects mostly developing countries with limited access to post-exposure prophylaxis and a low coverage of dog vaccination.

OBJECTIVE

This study estimates the burden of human rabies in Mali from the extrapolation of animal bite surveillance, mostly dogs, in the region of Sikasso and the District of Bamako in 2016 and 2017.

MATERIAL AND METHODS

Monte Carlo simulations of a series of interconnected probabilities were used to estimate the burden of rabies. The data was collected from cross-sectional surveys of 8775 households of which 4172 were in the District of Bamako and 4603 in the region of Sikasso. Further data was collected in health centres and from the respective veterinary services.

RESULTS

We estimate that in the year 2016 133 [95% Confidence Interval (95%CI) 87-186] people died and that 5'366 [95%CI 3'510-7'504] years of life (YLL) were lost and in 2017 et 136 [95%CI 96-181] people died and that 5530 [IC 95% 3'913-7'377] YLLs were lost. The loss of income was estimated at 3.2 million USD [95%CI 2,1-4,5] en 2016, and 3,3 million USD [95%CI 2,3-4,4] in 2017. This represents the highest financial loss from rabies, followed by the cost of postexposure prophylaxis (PEP) of 86'848 $USD and 89'371 $ USD respectively. From the whole cost of rabies in Mali, 92% of the cost in 2016 and 94% of those in 2017 were attributable to premature mortality and the cost of help seeking. The proportion of cost of PEP was 3% in 2016 and 2017 of the total cost of disease. The cost related to dog vaccination changed from 3% to 1% in the same time period.

CONCLUSION

This study shows that despite the possibility of preventing human rabies by PEP, its burden remains important in Malian communities. Rabies control by mass vaccination of dogs is hardly done and access to PEP is difficult. However, Rabies elimination by mass vaccination of dogs has been demonstrated to be feasible. Hence a coordinated regional effort between countries by funding dog mass vaccination and full access to PEP can eliminate rabies in West Africa.

Rabies surveillance-response in Mali in the past 18 years and requirements for the future

CONTEXT

Rabies is endemic in Mali, but little is known about the distribution of rabies and its surveillance across the country. Documenting the evolution of rabies and the problems related to surveillance is useful to facilitate elimination of human rabies by 2030.

METHOD

Data collected at the Central Veterinary Laboratory (LCV) from 1999 to 2017 and through the surveillance system functioning at household, health and veterinary structure levels, as established by the Global Vaccine Alliance funded project on the burden of rabies, between 2016 and 2017 in Bamako and the Sikasso region were used in this study. All data on animals examined for rabies by the direct fluorescence antibody test (DFA) during the specified time period were summarized, and the proportion of rabies positive tested among animals suspected of rabies was estimated. From the number of dogs tested positive for rabies, a cumulative incidence was estimated for the total canine population. The number of positive tested samples was divided by the product of the estimated canine population and number of years (18). In addition, the number of human rabies cases was analyzed to estimate a cumulative incidence.

RESULTS

Among all animal samples suspected for rabies, 93.2% [95% CI 90.6-95.3] were positive by the DFA test. From the 486 included animal samples, 94.7% [95% CI 92.3-96.5] were domestic dogs with 90.9% [95% CI 87.9-93.3] positive, which stands out as the main reservoir of rabies in Mali. Cats, cattle, sheep and donkeys also tested positive using the DFA test. The cumulative incidence of canine rabies was estimated at 0.371 [95% CI: 0.336-0.408] / 10'000 dogs. The highest incidence was observed in Bamako, the capital of Mali, with a cumulative incidence of 2.242 [95% CI: 2.001-2.504] / 10'000 dogs, followed by Koulikoro with 0.335 [95% CI: 0.258-0.429] / 10'000 dogs. For other areas far from LCV, the cumulative incidence was low, with zero in Kidal. Nationally reported cases of human rabies declined in recent years with an average of 12.6 [95% CI: 8.7-16.5] deaths per year. This result gives an annual incidence of 0.1047 [0.0742-0.1352] / 100'000 inhabitants.

CONCLUSION

Over the past 18 years, rabies is endemically stable in Mali despite the decrease in reported human cases. The disparity among regions in number of samples tested indicates a low level of clinical and laboratory surveillance and likely a high level of underreporting. Dogs play the main role in rabies transmission in Mali. Monitoring of and decisions for post-exposure prophylaxis (PEP) includes other animals (cats, cattle, and monkeys) involved in transmission. Mali should develop a national rabies strategy to include better communication between the public health and animal health sectors, strengthening of laboratory surveillance capacity, mass vaccination of dogs and guaranteed access to PEP.

Utility of rabies neutralizing antibody detection in cerebrospinal fluid and serum for ante-mortem diagnosis of human rabies

Background

Early ante-mortem laboratory confirmation of human rabies is essential to aid patient management and institute public health measures. Few studies have highlighted the diagnostic value of antibody detection in CSF/serum in rabies, and its utility is usually undermined owing to the late seroconversion and short survival in infected patients. This study was undertaken to examine the ante-mortem diagnostic utility and prognostic value of antibody detection by rapid fluorescent focus inhibition test (RFFIT) in cerebrospinal fluid (CSF)/serum samples received from clinically suspected human rabies cases from January 2015 to December 2017.

Methodology/Principal findings

Samples collected ante-mortem and post-mortem from 130 and 6 patients with clinically suspected rabies respectively, were received in the laboratory during the study period. Ante-mortem laboratory confirmation was achieved in 55/130 (42.3%) cases. Real time PCR for detection of viral nucleic acid performed on saliva, nuchal skin, brain tissue and CSF samples could confirm the diagnosis in 15 (27.2%) of the 55 laboratory confirmed cases. Ante-mortem diagnosis could be achieved by RFFIT (in CSF and/or serum) in 45 (34.6%) of the 130 clinically suspected cases, accounting for 81.8% of the total 55 laboratory confirmed cases. The sensitivity of CSF RFFIT increased with the day of sample collection (post-onset of symptoms) and was found to be 100% after 12 days of illness. Patients who had received prior vaccination had an increased probability of a positive RFFIT and negative PCR result. Patients who were positive by RFFIT alone at initial diagnosis had longer survival (albeit with neurological sequelae) than patients who were positive by PCR alone or both RFFIT and PCR.

Conclusions/Significance

Detection of antibodies in the CSF/serum is a valuable ante-mortem diagnostic tool in human rabies, especially in patients who survive beyond a week. It was also found to have a limited role as a prognostic marker to predict outcomes in patients.

Ante-mortem diagnosis of human rabies is essential for patient management and public health measures. The detection of virus specific antibodies in the CSF/serum of patients with suspected rabies is thought to have a limited diagnostic role owing to late seroconversion and short survival in rabies. We examined the diagnostic and prognostic utility of antibody detection by rapid fluorescent focus inhibition test (RFFIT) in CSF/serum samples received from clinically suspected human rabies cases (2015–2017). RFFIT (in CSF and/or serum) could confirm ante-mortem diagnosis in 45 (34.6%) of the 130 clinically suspected cases, accounting for 81.8% of the total 55 laboratory confirmed cases. The sensitivity of CSF RFFIT increased with the day of sample collection (post-onset of symptoms) and was found to be 100% after 12 days of illness. Patients who had received prior vaccination had an increased likelihood of a positive RFFIT and negative PCR result. Patients who were positive by RFFIT alone at initial diagnosis had longer duration of survival, although with poor functional outcomes. Antibody detection by RFFIT in CSF/serum was found to have a diagnostic utility especially in patients who survived beyond a week and a limited prognostic role in human rabies.

Diagnostic approach to encephalitis and meningoencephalitis in adult returning travellers

BACKGROUND

Encephalitis and meningoencephalitis are severe, sometime life-threatening infections of the central nervous system. Travellers may be exposed to a variety of neurotropic pathogens.

AIMS

We propose to review known infectious causes of encephalitis in adults acquired outside Europe, and how to identify them.

SOURCES

We used Pubmed and Embase, to search the most relevant publications over the last years.

CONTENT

Microbiologic tests and radiological tools to best identify the causative pathogen in travellers presenting with encephalitis and ME are presented in this narrative review, as well as a diagnostic approach tailored to the visited area and types of exposures.

IMPLICATIONS

This review highlights the diagnostic difficulties inherent to exotic causes of central nervous system infections, and attempts to guide clinicians with respect to which microbiological tests to consider, in addition to brain MRI, when approaching a returning traveller presenting with encephalitis.

Syndrome Evaluation System for Simultaneous Detection of Pathogens Causing Acute Encephalitic Syndrome in India, Part-2: Validation Using Well Characterized Clinical Samples

Diagnosis of the aetiological agent in case of acute encephalitic syndrome (AES) continues to pose a challenge in clinical practice as a variety of pathogens are known to cause AES. Here, we report the validation of a Syndrome Evaluation System (SES) developed for simultaneous detection of multiple AES pathogens using a well characterized set of Cerebrospinal fluid (CSF) samples. The validation of the SES was carried out in two phases. In the first phase, the SES was validated using 51 CSF samples obtained from autopsy proven cases and 50 samples obtained from apparently healthy individuals undergoing spinal anesthesia for minor surgeries served as "controls." The SES detected etilogical agent in 48/51 (94.11 %) samples obtained from autopsy proven AES cases while all the 50 CSF samples obtained from "controls" were negative. In the second phase, the SES was validated using well characterized CSF samples obtained from AES patients fulfilling the WHO case definition of AES (Group I; n = 207) and samples that were collected from patients with non-infectious neurological disorder (Group II; n = 90). All the samples were tested using multiple conventional/serological assays and categorized into various groups. Amongst the AES cases fulfilling WHO case definition, the SES detected AES pathogens in 160/207 (77.29%) cases while conventional serological/molecular assays were able to detect AES pathogens only in 77/207 (37.1%) of cases. Further, in 12/83 CSF samples that were positive by SES and negative by conventional serological/molecular tests, the results were additionally confirmed by sequencing the PCR products to rule out non-specific amplification in the SES. In patients with non-infectious neurological disorders the SES detected latent viruses 12/90 CSF samples. These results indicate that the SES, apart being a rapid, sensitive, specific, and cost-effective method provides the major advantage of simultaneous detection of multiple pathogens using as single specimen of CSF.

Improving systematic rabies surveillance in Cameroon: A pilot initiative and results for 2014-2016

Canine rabies is endemic in Cameroon, but human rabies exposures and cases are likely underreported because of inadequate surveillance. In 2014, the surveillance network in the West region of Cameroon was reinforced by introducing a new anti-rabies center, a framework for data collection and evaluation, provisions for sample collecting and laboratory confirmation, and training for health professionals. The objective of this observational cohort study was to describe the incidence and characteristics of reported exposures and human and animal rabies cases following this reinforcement of the existing rabies surveillance system. The surveillance network consisted of local, regional, and national health and veterinary authorities in 11 of the 20 West region districts, and was completely integrated within the existing national rabies surveillance network. Animal exposures and suspected rabies exposures, the suspected rabid animals involved, and laboratory confirmation of human and animal rabies cases were recorded in a centralized information database. Between January 2014 and June 2016, the network recorded 1340 animal exposure cases for an overall incidence rate of 38.2 animal exposures per 100,000 people, four confirmed rabies-positive animals, and one confirmed human rabies case out of four clinically suspected cases. In contrast, 62 animal exposures and an overall incidence rate of 6.1 exposures per 100,000 people were reported for the West region districts not participating in the reinforced surveillance. Of the 925 animal exposure victims for whom a detailed case report form was completed, 703 were considered to be at risk of rabies and only 428 (61%) of these received any post-exposure prophylaxis in the form of rabies vaccine. Obstacles encountered within the network included low rates of animal sample submission and animal follow-up by veterinarians. Reinforced rabies surveillance in the West region of Cameroon has provided the most accurate estimate of the region's disease and exposure burdens to date, and indicates that animal exposures are substantially underreported. The reinforced network also signaled that greater access to post-exposure prophylaxis is needed. Integration of regions not covered by the surveillance network and efforts to improve engagement of veterinary services will be needed to reveal the true burden of rabies in Cameroon.

Evaluation of Enzyme Linked Immuno-Sorbent Assay and Rapid Immuno-Diagnostic Test for Rabies Antigen Detection in Archived Dog Brain Tissues

Rabies urgently requires strengthening of new and existing diagnostic methodology in order to overcome the threat it poses. We evaluated the Enzyme Linked Immuno-Sorbent Assay (ELISA) and the Rapid Immunodiagnostic Test (RIDT) in detecting rabies viral antigens, comparing both tests with the Direct Fluorescent Antibody Test (DFAT) which is the gold standard in rabies diagnosis. Fifty dog brain tissues collected from the archives of the Central Diagnostic Laboratory, National Veterinary Research Institute, Vom, Nigeria, were utilized for this study. ELISA performed better than RIDT and recorded equivalent result with DFAT as compared with RIDT. There was a 96 % agreement between ELISA and DFAT for rabies antigen detection (concordance coefficient 78 % : 95 % C. I. 0.6366 to 0.8654) while there was a 54 % agreement between RIDT and DFAT (concordance coefficient 17 % : 95 % C. I. 0.05138—0.2752). Compared to DFAT, the sensitivities of ELISA and RIDT were 95.5 % and 47.6 %, respectively, and the specificities of ELISA and RIDT were 100 % and 87.5 % respectively. The simple Cohen’s kappa coefficient for ELISA related to the DFAT was found to be 0.834 (95 % C. I. 0.613—1.0). For RIDT, the Kappa value was 0.170 (95 % C. I. 0.003—0.337). The ELISA is as reliable a diagnostic method as the DFAT which is the gold standard for rabies diagnosis. It has an advantage of being able to analyse large number of samples at the same time, making it more suitable for epidemiological studies and for laboratories that cannot perform the DFAT. The unsatisfactory result of RIDT in this study reiterates the need to perform an adequate test validation before it can be used in the laboratory for rabies diagnosis.

Application and Comparative Evaluation of Fluorescent Antibody, Immunohistochemistry and Reverse Transcription Polymerase Chain Reaction Tests for the Detection of Rabies Virus Antigen or Nucleic Acid in Brain Samples of Animals Suspected of Rabies in India

Accurate and early diagnosis of animal rabies is critical for undertaking public health measures. Whereas the direct fluorescent antibody (DFA) technique is the recommended test, the more convenient, direct rapid immunochemistry test (dRIT), as well as the more sensitive, reverse transcription polymerase chain reaction (RT-PCR), have recently been employed for the laboratory diagnosis of rabies. We compared the three methods on brain samples from domestic (dog, cat, cattle, buffalo, horse, pig and goat) and wild (leopard, wolf and jackal) animals from various parts of India. Of the 257 samples tested, 167 were positive by all the three tests; in addition, 35 of the 36 decomposed samples were positive by RT-PCR. This is the first study in which such large number of animal samples have been subjected to the three tests simultaneously. The results confirm 100% corroboration between DFA and dRIT, buttress the applicability of dRIT in the simple and rapid diagnosis of rabies in animals, and reaffirm the suitability of RT-PCR for samples unfit for testing either by DFA or dRIT.

The Imperative of Palliation in the Management of Rabies Encephalomyelitis

The aim of this review is to guide clinicians in the practical management of patients suffering from rabies encephalomyelitis. This condition is eminently preventable by modern post-exposure vaccination, but is virtually always fatal in unvaccinated people. In the absence of any proven effective antiviral or other treatment, palliative care is an imperative to minimise suffering. Suspicion of rabies encephalomyelitis depends on recognising the classic symptomatology and eliciting a history of exposure to a possibly rabid mammal. Potentially treatable differential diagnoses must be eliminated, notably other infective encephalopathies. Laboratory confirmation of suspected rabies is not usually possible in many endemic areas, but is essential for public health surveillance. In a disease as agonising and terrifying as rabies encephalomyelitis, alleviation of distressing symptoms is the primary concern and overriding responsibility of medical staff. Calm, quiet conditions should be created, allowing relatives to communicate with the dying patient in safety and privacy. Palliative management must address thirst and dehydration, fever, anxiety, fear, restlessness, agitation, seizures, hypersecretion, and pain. As the infection progresses, coma and respiratory, cardiovascular, neurological, endocrine, or gastrointestinal complications will eventually ensue. When the facilities exist, the possibility of intensive care may arise, but although some patients may survive, they will be left with severe neurological sequelae. Recovery from rabies is extremely rare, and heroic measures with intensive care should be considered only in patients who have been previously vaccinated, develop rabies antibody within the first week of illness, or were infected by an American bat rabies virus. However, in most cases, clinicians must have the courage to offer compassionate palliation whenever the diagnosis of rabies encephalomyelitis is inescapable.

Development of molecular confirmation tools for swift and easy rabies diagnostics

BACKGROUND

As rabies still represents a major public threat with tens of thousands of deaths per year, particularly in developing countries, adequate surveillance based on rapid and reliable rabies diagnosis for both humans and animals is essential. Rabies diagnosis relies on highly sensitive and specific laboratory tests for detection of viral antigens. Among those tests, at present the immunofluorescence antibody test is the "gold standard test" for rabies diagnosis, followed by virus isolation in either mice or cell culture. Because of the advantages of molecular assays in terms of sensitivity and applicability their approval as confirmatory diagnostic test by international organizations (OIE, WHO) is envisaged. Therefore, the objective was to develop and validate novel molecular assays and RNA extraction methods for rabies that reduce the turnaround time but remain highly sensitive and specific.

METHODS

Here, novel assays, i.e. HighSpeed RT-qPCR and isothermal recombinase polymerase amplification (RPA) were designed and tested. Furthermore, three magnetic bead-based rapid extraction methods for manual or automated extraction were validated and combined with the new downstream assays.

RESULTS

While the conventional column based RNA extraction method showed the highest intra-run variations, all magnetic bead-based rapid extraction methods delivered nearly comparable sensitivity and efficiency of RNA recovery. All newly developed molecular tests were able to detect different rabies virus strains in a markedly reduced timeframe in comparison to the standard diagnostic assays. The observed detection limit for the HighSpeed RT-qPCR was 10 genome copies per reaction, and 1000 genome copies per reaction for the RPA assay.

CONCLUSION

Magnetic bead-based rapid RNA extraction methods are highly sensitive and show a high level of reproducibility and therefore, are particularly suitable for molecular diagnostic assays including rabies. In addition, with a detection limit of 10 genome copies per reaction, the HighSpeed RT-qPCR is suitable for rapid ante mortem rabies diagnosis in humans as well as confirmatory test in integrated bite management and subsequent post-exposure prophylaxis.

Bites from the same dog, different outcomes for two patients: a case report

BACKGROUND

Rabies is a serious reemerging zoonosis in China. At present human rabies cases are primarily diagnosed based on clinical presentation.

CASE PRESENTATION

In August 2012, a woman and her son were attacked by a stray dog in Henan, China. The son received rabies postexposure prophylaxis (wound treatment followed by vaccine, no immunoglobulin), however, the mother did not. Rabies infection was subsequently laboratory confirmed in the mother and she died in December; her son is alive and healthy after 2 years of follow-up.

CONCLUSION

This report documents that the timely utilization of postexposure prophylaxis is a required measure in preventing rabies after exposure to an animal bite.

Re-emerging of rabies in Shaanxi province, China, from 2009 to 2015

To explore the epidemiological, phylogeographic, and migration characteristics of human rabies in Shaanxi province, China from 2009 to 2015. The collected data were described and the sequenced glycoprotein (G) and nucleoprotein (N) genes were implemented to estimate the evolutionary rates and phylogeographic patterns using BEAST v.1.8.2. A total of 269 rabies cases were reported and 70.26% of the cases were male and 61.71% were between the ages of 19-59. The majority of the cases were farmers (83.27%). The estimated evolutionary rate of the N genes was 2.4 × 10^-4 substitutions/site/year and the G genes was 3.4 × 10^-4 . The time of the most recent common ancestor (TMRCA) was estimated around 1990. We detected viral migration paths from Sichuan, Guizhou, and Hunan to Hanzhong prefecture of Shaanxi and then spreaded to Xi'an and other prefectures. The main population affected by rabies virus was male adult farmers. The evolution rate of rabies viruses in Shaanxi was similar with the prior results reported by others and the ancestor virus should be circulating in neighboring province Sichuan around 1990 and then transmitted to Shaanxi. Promptly standard wound treatment and timely post-exposure prophylaxis should be compulsory for the dog-bitten victims.

Development and validation of sensitive real-time RT-PCR assay for broad detection of rabies virus

Rabies virus (RABV) remains one of the most important global zoonotic pathogens. RABV causes rabies, an acute encephalomyelitis associated with a high rate of mortality in humans and animals and affecting different parts of the world, particularly in Asia and Africa. Confirmation of rabies diagnosis relies on laboratory diagnosis, in which molecular techniques such as detection of viral RNA by reverse transcription polymerase chain reaction (RT-PCR) are increasingly being used. In this study, two real-time quantitative RT-PCR assays were developed for large-spectrum detection of RABV, with a focus on African isolates. The primer and probe sets were targeted highly conserved regions of the nucleoprotein (N) and polymerase (L) genes. The results indicated the absence of non-specific amplification and cross-reaction with a range of other viruses belonging to the same taxonomic family, i.e. Rhabdoviridae, as well as negative brain tissues from various host species. Analytical sensitivity ranged between 100 to 10 standard RNA copies detected per reaction for N-gene and L-gene assays, respectively. Effective detection and high sensitivity of these assays on African isolates showed that they can be successfully applied in general research and used in diagnostic process and epizootic surveillance in Africa using a double-check strategy.

The Recently Discovered Bokeloh Bat Lyssavirus: Insights Into Its Genetic Heterogeneity and Spatial Distribution in Europe and the Population Genetics of Its Primary Host

In 2010, a novel lyssavirus named Bokeloh bat lyssavirus (BBLV) was isolated from a Natterer's bat (Myotis nattereri) in Germany. Two further viruses were isolated in the same country and in France in recent years, all from the same bat species and all found in moribund or dead bats. Here we report the description and the full-length genome sequence of five additional BBLV isolates from Germany (n=4) and France (n=1). Interestingly, all of them were isolated from the Natterer's bat, except one from Germany, which was found in a common Pipistrelle bat (Pipistrellus pipistrellus), a widespread and abundant bat species in Europe. The latter represents the first case of transmission of BBLV to another bat species. Phylogenetic analysis clearly demonstrated the presence of two different lineages among this lyssavirus species: lineages A and B. The spatial distribution of these two lineages remains puzzling, as both of them comprised isolates from France and Germany; although clustering of isolates was observed on a regional scale, especially in Germany. Phylogenetic analysis based on the mitochondrial cytochrome b (CYTB) gene from positive Natterer's bat did not suggest a circulation of the respective BBLV sublineages in specific Natterer's bat subspecies, as all of them were shown to belong to the M. nattereri sensu stricto clade/subspecies and were closely related (German and French positive bats). At the bat host level, we demonstrated that the distribution of BBLV at the late stage of the disease seems large and massive, as viral RNA was detected in many different organs.

Dual Combined Real-Time Reverse Transcription Polymerase Chain Reaction Assay for the Diagnosis of Lyssavirus Infection

The definitive diagnosis of lyssavirus infection (including rabies) in animals and humans is based on laboratory confirmation. The reference techniques for post-mortem rabies diagnosis are still based on direct immunofluorescence and virus isolation, but molecular techniques, such as polymerase chain reaction (PCR) based methods, are increasingly being used and now constitute the principal tools for diagnosing rabies in humans and for epidemiological analyses. However, it remains a key challenge to obtain relevant specificity and sensitivity with these techniques while ensuring that the genetic diversity of lyssaviruses does not compromise detection. We developed a dual combined real-time reverse transcription polymerase chain reaction (combo RT-qPCR) method for pan-lyssavirus detection. This method is based on two complementary technologies: a probe-based (TaqMan) RT-qPCR for detecting the RABV species (pan-RABV RT-qPCR) and a second reaction using an intercalating dye (SYBR Green) to detect other lyssavirus species (pan-lyssa RT-qPCR). The performance parameters of this combined assay were evaluated with a large panel of primary animal samples covering almost all the genetic variability encountered at the viral species level, and they extended to almost all lyssavirus species characterized to date. This method was also evaluated for the diagnosis of human rabies on 211 biological samples (positive n = 76 and negative n = 135) including saliva, skin and brain biopsies. It detected all 41 human cases of rabies tested and confirmed the sensitivity and the interest of skin biopsy (91.5%) and saliva (54%) samples for intra-vitam diagnosis of human rabies. Finally, this method was successfully implemented in two rabies reference laboratories in enzootic countries (Cambodia and Morocco). This combined RT-qPCR method constitutes a relevant, useful, validated tool for the diagnosis of rabies in both humans and animals, and represents a promising tool for lyssavirus surveillance.

Evaluation of Six Commercially Available Rapid Immunochromatographic Tests for the Diagnosis of Rabies in Brain Material

Rabies is a neglected zoonotic disease that causes an estimated 60,000 human deaths annually. The main burden lies on developing countries in Asia and Africa, where surveillance and disease detection is hampered by absence of adequate laboratory facilities and/or the difficulties of submitting samples from remote areas to laboratories. Under these conditions, easy-to-use tests such as immunochromatographic assays, i.e. lateral flow devices (LFD), may increase surveillance and improve control efforts. Several LFDs for rabies diagnosis are available but, except for one, there are no data regarding their performance. Therefore, we compared six commercially available LFDs for diagnostic and analytical sensitivity, as well as their specificity and their diagnostic agreement with standard rabies diagnostic techniques using different sample sets, including experimentally infected animals and several sets of field samples. Using field samples the sensitivities ranged between 0% up to 100% depending on the LFD and the samples, while for experimentally infected animals the maximum sensitivity was 32%. Positive results in LFD could be further validated using RT-qPCR and sequencing. In summary, in our study none of the tests investigated proved to be satisfactory, although the results somewhat contradict previous studies, indicating batch to batch variation. The high number of false negative results reiterates the necessity to perform a proper test validation before being marketed and used in the field. In this respect, marketing authorization and batch release control could secure a sufficient quality for these alternative tests, which could then fulfil their potential.

Despite being preventable with adequate biologicals, rabies still causes an estimated 60,000 human deaths annually. The main burden lies on developing countries in Asia and Africa, where dog rabies surveillance is hampered by laboratory confirmation of disease due to a number of reasons, including laboratory infrastructure and logistics. Lateral flow devices (LFD) may increase surveillance and improve control efforts. Several LFDs for rabies diagnosis are available but, except for one, there are no data available regarding their performance. Therefore, we compared six commercially available LFDs for diagnostic and analytical sensitivity. With sensitivities ranging from 0% up to 100% depending on the LFD and the samples, none of the tests investigated proved to be satisfactory, and the results somewhat contradict previous studies, indicating batch to batch variation. The high number of false negative results reiterates the necessity to perform a proper test validation before being marketed and used in the field. Only when sufficient quality is assured for these alternative tests, then they can fulfil their potential. In this respect, we demonstrated that positive results in LFD can be further validated and characterized using RT-qPCR and sequencing.

Severe ketoalkalosis as initial presentation of imported human rabies in France

We report a patient with an unusual initial metabolic presentation of imported human rabies who became symptomatic within 2 weeks of returning from Mali to France. This is the single case of imported human rabies identified in France within the past 11 years and the first report of viral RNA in bronchial secretions.

Molecular double-check strategy for the identification and characterization of European Lyssaviruses

The "gold standard" for post-mortem rabies diagnosis is the direct fluorescent antibody test (FAT). However, in the case of ante-mortem non-neural sample material or decomposed tissues, the FAT reaches its limit, and the use of molecular techniques can be advantageous. In this study, we developed and validated a reverse transcription PCR cascade protocol feasible for the classification of samples, even those for which there is no epidemiological background knowledge. This study emphasises on the most relevant European lyssaviruses. In a first step, two independent N- and L-gene based pan-lyssavirus intercalating dye assays are performed in a double-check application to increase the method's diagnostic safety. For the second step, characterization of the lyssavirus positive samples via two independent multiplex PCR-systems was performed. Both assays were probe-based, species-specific multiplex PCR-systems for Rabies virus, European bat lyssavirus type 1 and 2 as well as Bokeloh bat lyssavirus. All assays were validated successfully with a comprehensive panel of lyssavirus positive samples, as well as negative material from various host species. This double-check strategy allows for both safe and sensitive screening, detection and characterization of all lyssavirus species of humans and animals, as well as the rapid identification of currently unknown lyssaviruses in bats in Europe.

Recent emergence and spread of an Arctic-related phylogenetic lineage of rabies virus in Nepal

Rabies is a zoonotic disease that is endemic in many parts of the developing world, especially in Africa and Asia. However its epidemiology remains largely unappreciated in much of these regions, such as in Nepal, where limited information is available about the spatiotemporal dynamics of the main etiological agent, the rabies virus (RABV). In this study, we describe for the first time the phylogenetic diversity and evolution of RABV circulating in Nepal, as well as their geographical relationships within the broader region. A total of 24 new isolates obtained from Nepal and collected from 2003 to 2011 were full-length sequenced for both the nucleoprotein and the glycoprotein genes, and analysed using neighbour-joining and maximum-likelihood phylogenetic methods with representative viruses from all over the world, including new related RABV strains from neighbouring or more distant countries (Afghanistan, Greenland, Iran, Russia and USA). Despite Nepal's limited land surface and its particular geographical position within the Indian subcontinent, our study revealed the presence of a surprising wide genetic diversity of RABV, with the co-existence of three different phylogenetic groups: an Indian subcontinent clade and two different Arctic-like sub-clades within the Arctic-related clade. This observation suggests at least two independent episodes of rabies introduction from neighbouring countries. In addition, specific phylogenetic and temporal evolution analysis of viruses within the Arctic-related clade has identified a new recently emerged RABV lineage we named as the Arctic-like 3 (AL-3) sub-clade that is already widely spread in Nepal.

Rabies is endemic in most Asian countries and represents a serious public health issue, with an estimated 31,000 people dying each year of this disease. The majority of human cases are transmitted by domestic dogs, which act as the principal reservoir host and vector. However, molecular epidemiology and evolutionary dynamics of the main etiological agent, the rabies virus (RABV), remains largely unappreciated in some regions such as in Nepal. Based on a subset of 24 new Nepalese isolates collected from 2003 to 2011 and representative RABV strains at a global scale, phylogenetic analysis based on the complete nucleoprotein and glycoprotein genes sequences revealed the presence of a surprising wide genetic diversity of RABV circulating in this country. The presence of three different co-existing phylogenetic groups was identified: an Indian subcontinent clade and two different Arctic-like sub-clades within the Arctic-related clade, namely Arctic-like (AL)-1, lineage a (AL-1a), and AL-3. Among these clusters, the AL-3 sub-clade appears as the major Nepalese phylogroup which emerged relatively recently in this country, within the last 30 years. These data has raised some concerns about the exchange of RABV between different countries, and provided key elements for implementation of effective control measures of rabies in Nepal.

Surveillance and control of rabies in La Reunion, Mayotte, and Madagascar

Mayotte and La Reunion islands are currently free of animal rabies and surveillance is performed by the French Human and Veterinary Public Health Services. However, dog rabies is still enzootic in Madagascar with 4 to 10 confirmed human cases each year. The number of antirabies medical centres in Madagascar is still scarce to provide easy access to the local population for post-exposure rabies prophylaxis. Furthermore, stray dog populations are considerable and attempts to control rabies by mass campaigns of dog vaccination have not received sufficient attention from the national health authorities. To address these challenges, an expanded program to control rabies needs to be initiated by the Malagasy authorities.

Imported human rabies cases worldwide, 1990-2012

Sixty cases of human rabies in international travelers were reviewed from 1990-2012. A significant proportion of the cases were observed in migrants or their descendants when emigrating from their country of origin or after a trip to visit friends and relatives or for other reasons (43.3%). The cases were not necessarily associated with long-term travel or expatriation to endemic countries; moreover, cases were observed in travelers after short trips of two weeks or less. A predominance of male patients was observed (75.0%). The proportion of children was low (11.7%). Cases from India and Philippines were frequent (16 cases/60). In a significant proportion of cases (51.1%), diagnosis was challenging, with multiple missed diagnoses and transfers from ward to ward before the final diagnosis of rabies. Among the 28 patients whose confirmed diagnosis was obtained ante-mortem, the mean time between hospitalization and diagnosis was 7.7 days (median time: 6.0 days, range 2-30) including four cases with a diagnosis delayed by 15 or more days. In five cases, a patient traveled through one or more countries before ultimately being hospitalized. Three factors played a role in delaying the diagnosis of rabies in a number of cases: (i) a low index of suspicion for rabies in countries where the disease has been eradicated for a long time or is now rare, (ii) a negative history of animal bites or exposure to rabies, and (iii) atypical clinical presentation of the disease. Clinical symptomatology of rabies is complex and commonly confuses physicians. Furthermore, failure in diagnosing imported cases in more developed countries is most likely related to the lack of medical familiarity with even the typical clinical features of the disease.

A step forward in molecular diagnostics of lyssaviruses--results of a ring trial among European laboratories

Rabies is a lethal and notifiable zoonotic disease for which diagnostics have to meet the highest standards. In recent years, an evolution was especially seen in molecular diagnostics with a wide variety of different detection methods published. Therefore, a first international ring trial specifically designed on the use of reverse transcription polymerase chain reaction (RT-PCR) for detection of lyssavirus genomic RNA was organized. The trial focussed on assessment and comparison of the performance of conventional and real-time assays. In total, 16 European laboratories participated. All participants were asked to investigate a panel of defined lyssavirus RNAs, consisting of Rabies virus (RABV) and European bat lyssavirus 1 and 2 (EBLV-1 and -2) RNA samples, with systems available in their laboratory.

The ring trial allowed the important conclusion that conventional RT-PCR assays were really robust assays tested with a high concordance between different laboratories and assays. The real-time RT-PCR system by Wakeley et al. (2005) in combination with an intercalating dye, and the combined version by Hoffmann and co-workers (2010) showed good sensitivity for the detection of all RABV samples included in this test panel. Furthermore, all used EBLV-specific assays, real-time RT-PCRs as well as conventional RT-PCR systems, were shown to be suitable for a reliable detection of EBLVs. It has to be mentioned that differences were seen in the performance between both the individual RT-PCR systems and the laboratories. Laboratories which used more than one molecular assay for testing the sample panel always concluded a correct sample result.

Due to the markedly high genetic diversity of lyssaviruses, the application of different assays in diagnostics is needed to achieve a maximum of diagnostic accuracy. To improve the knowledge about the diagnostic performance proficiency testing at an international level is recommended before using lyssavirus molecular diagnostics e.g. for confirmatory testing.

Six fatal cases of classical rabies virus without biting incidents, Iran 1990-2010

BACKGROUND

Rabies is an endemic fatal zoonotic disease, commonly transmitted to humans through contact (bites and scratches) with infected animals.

OBJECTIVES

During the years 1990-2010, six patients with the clinical symptoms of rabies (fever, tinnitus, buzzing, delirium and hydrophobia), with no history of a bite, were diagnosed by physicians in Iran. To obtain laboratory confirmation of rabies infection, different clinical specimens from each patient were sent to the World Health Organisation (WHO) Collaborating Center for Reference and Research on Rabies, Pasteur Institute of Iran. The first case was a 39-year-old male veterinary technician who entered his uncovered scratched hand into the mouth of a rabid bovine and became infected. Two years later, a herd of sheep being tended by a shepherd and his two sons were attacked by a rabid wolf. All three individuals were infected when they applied burnt thorny wool to the sheep's wounds as a bandage. Their hands were scratched and then infected through contact with the remaining saliva of the rabid wolf on the sheep's wounds. In 1994, two other human cases occurred through corneal transplantation from the same donor who had died with the clinical signs of food poisoning (according to his hospital record), which probably was a misdiagnosis of rabies infection.

STUDY DESIGN

This is a case series study that describes human rabies cases without biting incidents. According to the WHO recommendation, human rabies cases are notifiable, therefore, in Iran, a rabies surveillance system has been established to follow these cases. During the last decade, six patients with no 'history of a bite' were hospitalised with growing symptoms of rabies. The data were collected from each patient by the physicians and transferred to the Ministry of Health and Medical Education of Iran, and to the WHO Collaborating Center for Reference and Research on Rabies, Pasteur Institute of Iran as the only testing laboratory. Thus, they came to the attention of the surveillance system. Ante-mortem diagnosis was performed on saliva, cerebrospinal fluid and blood samples that were collected from the first patient by the physicians. Fresh brain specimens from all patients were kept in a mixture of 50% glycerol in phosphate-buffered saline and transported on ice to the WHO Collaborating Center for Reference and Research on Rabies.

RESULTS

For the first patient, rabies virus was investigated in saliva using the rapid tissue cell inoculation test (RTCIT) and the mouse inoculation test (MIT). Anti-rabies antibodies in this patient's serum and cerebrospinal fluid (CSF) were examined using the mouse neutralisation test (MNT). Fresh brain specimens from all patients were examined using the fluorescence antibody test (FAT) as recommended by the WHO laboratory manual in rabies as the post-mortem diagnostic test for rabies. Rabies infection was confirmed in all of the deceased patients. Anti-rabies antibodies were identified only in one patient's serum specimen. Testing also showed that the rabies virus isolated was the classic rabies virus (serotype 1), which is widespread in Iran.

CONCLUSIONS

Prevention and control of this fatal disease require a sensitive surveillance system to follow 'suspected' animal and human rabies cases thoroughly through the improved reporting system, which contains the history of exposure, clinical examinations, symptoms and laboratory results. This study describes some notable human rabies infections and their transmission modes to prevent occupational accidents.

Evaluation of a monoclonal antibody-based rapid immunochromatographic test for direct detection of rabies virus in the brain of humans and animals

Rabies diagnosis uses a direct fluorescent antibody test (FAT) that is difficult, costly, and time-consuming, and requires trained personnel. We developed a rapid immunochromatographic test (RICT) for the diagnosis of rabies. The efficacy of the RICT was compared with that of the FAT. Brain samples were collected from humans, dogs, cats, and other animals in Sri Lanka (n = 248), Bhutan (n = 27), and Thailand (n = 228). The sensitivity (0.74-0.95), specificity (0.98-1.0), positive predictive value (0.98-1.0), negative predictive value (0.75-0.97), accuracy (0.91-0.98), and kappa measure of agreement (0.79-0.93) were all satisfactory for animal samples and samples preserved in 50% glycerol saline solution. Because the RICT showed high sensitivity but low specificity with human brain samples, it is unsuitable for confirming rabies in humans. No amino acid substitutions were found in the antibody attachment sites of the nucleoprotein gene with FAT-positive, RICT-negative samples. The RICT is reliable, user friendly, rapid, robust, and can be used in laboratories with a modest infrastructure.

First human rabies case in French Guiana, 2008: epidemiological investigation and control

BACKGROUND

Until 2008, human rabies had never been reported in French Guiana. On 28 May 2008, the French National Reference Center for Rabies (Institut Pasteur, Paris) confirmed the rabies diagnosis, based on hemi-nested polymerase chain reaction on skin biopsy and saliva specimens from a Guianan, who had never travelled overseas and died in Cayenne after presenting clinically typical meningoencephalitis.

METHODOLOGY/PRINCIPAL FINDINGS

Molecular typing of the virus identified a Lyssavirus (Rabies virus species), closely related to those circulating in hematophagous bats (mainly Desmodus rotundus) in Latin America. A multidisciplinary Crisis Unit was activated. Its objectives were to implement an epidemiological investigation and a veterinary survey, to provide control measures and establish a communications program. The origin of the contamination was not formally established, but was probably linked to a bat bite based on the virus type isolated. After confirming exposure of 90 persons, they were vaccinated against rabies: 42 from the case's entourage and 48 healthcare workers. To handle that emergence and the local population's increased demand to be vaccinated, a specific communications program was established using several media: television, newspaper, radio.

CONCLUSION/SIGNIFICANCE

This episode, occurring in the context of a Department far from continental France, strongly affected the local population, healthcare workers and authorities, and the management team faced intense pressure. This observation confirms that the risk of contracting rabies in French Guiana is real, with consequences for population educational program, control measures, medical diagnosis and post-exposure prophylaxis.

Lyssavirus detection and typing using pyrosequencing

Rabies is a fatal zoonosis caused by a nonsegmented negative-strand RNA virus, namely, rabies virus (RABV). Apart from RABV, at least 10 additional species are known as rabies-related lyssaviruses (RRVs), and some of them are responsible for occasional spillovers into humans. More lyssaviruses have also been detected recently in different bat ecosystems, thanks to the application of molecular diagnostic methods. Due to the variety of the members of the genus Lyssavirus, there is the necessity to develop a reliable molecular assay for rabies diagnosis able to detect and differentiate among the existing rabies and rabies-related viruses. In the present study, a pyrosequencing protocol targeting the 3' terminus of the nucleoprotein (N) gene was applied for the rapid characterization of lyssaviruses. Correct identification of species was achieved for each sample tested. Results from the pyrosequencing assay were also confirmed by those obtained using the Sanger sequencing method. A pan-lyssavirus one-step reverse transcription (RT)-PCR was developed within the framework of the pyrosequencing procedure. The sensitivity (Se) of the one-step RT-PCR assay was determined by using in vitro-transcribed RNA and serial dilutions of titrated viruses. The assay demonstrated high analytical and relative specificity (Sp) (98.94%) and sensitivity (99.71%). To date, this is the first case in which pyrosequencing has been applied for lyssavirus identification using a cheaper diagnostic approach than the one for all the other protocols for rapid typing that we are acquainted with. Results from this study indicate that this procedure is suitable for lyssavirus detection in samples of both human and animal origin.