A case of human rabies in Kansas: epidemiologic, clinical, and laboratory considerations

Vital Signs: Trends in Human Rabies Deaths and Exposures - United States, 1938-2018

Introduction

Each year, rabies causes approximately 59,000 deaths worldwide, including approximately two deaths in the United States. Before 1960, dogs were a common reservoir of rabies in the United States; however, increasingly, species of wildlife (e.g., bats, raccoons) are the main reservoirs. This report characterizes human rabies deaths, summarizes trends in rabies mortality, and highlights current rabies risks in the United States.

Methods

Rabies trends in the United States during 1938–2018 were analyzed using national rabies surveillance data. Data from the Healthcare Cost and Utilization Project for 2006–2014 were used to estimate the number of postexposure prophylaxis (PEP) visits per 100,000 persons during 2017–2018. The Centers for Medicare & Medicaid Services’ average sales price data were used to estimate PEP costs.

Results

From 1960 to 2018, a total of 125 human rabies cases were reported in the United States; 36 (28%) were attributed to dog bites during international travel. Among the 89 infections acquired in the United States, 62 (70%) were attributed to bats. In 2018, approximately 55,000 persons sought PEP after contact with a potentially rabid animal.

Conclusions and Comments

In the United States, wildlife rabies, especially in bats, continues to pose a risk to humans. Travelers also might be exposed to canine rabies in countries where the disease is still present; increased awareness of rabies while traveling abroad is needed. Vaccinating pets, avoiding contact with wildlife, and seeking medical care if one is bitten or scratched by an animal are the most effective ways to prevent rabies. Understanding the need for timely administration of PEP to prevent death is critical.

Virology, immunology and pathology of human rabies during treatment

BACKGROUND

Rabies is an acute fatal encephalitis caused by all members of the Lyssavirus genus. The first human rabies survivor without benefit of prior vaccination was reported from Milwaukee in 2005. We report a second unvaccinated patient who showed early recovery from rabies and then died accidentally during convalescence, providing an unparalleled opportunity to examine the histopathology as well as immune and virological correlates of early recovery from human rabies.

METHODS

Case report, rapid fluorescent focus inhibition test, enzyme-linked immunosorbent assay, indirect and direct fluorescent antibody assays, reverse-transcriptase polymerase chain reaction, phylogenetic reconstruction, isolation in tissue culture, pathology and immunohistochemistry.

RESULTS

The 9 year old died 76 days after presenting with rabies of vampire bat phylogeny transmitted by cat bite. Antibody response in serum and cerebrospinal fluid was robust and associated with severe cerebral edema. No rabies virus was cultured at autopsy. Rabies virus antigen was atypical in size and distribution. Rabies virus genome was present in neocortex but absent in brainstem.

CONCLUSIONS

Clinical recovery was associated with detection of neutralizing antibody and clearance of infectious rabies virus in the central nervous system by 76 days but not clearance of detectable viral subcomponents such as nucleoprotein antigen or RNA in brain.

Diagnosis, management and post-mortem findings of a human case of rabies imported into the United Kingdom from India: a case report

BACKGROUND

Human rabies infection continues to be a significant public health burden globally, and is occasionally imported to high income settings where the Milwaukee Protocol for intensive care management has recently been employed, with limited success in improving survival. Access to molecular diagnostics, pre- and post-mortem, and documentation of pathophysiological responses while using the Milwaukee protocol, can add useful insights for the future of rabies management.

CASE PRESENTATION

A 58-year-old British Asian woman was referred to a regional general hospital in the UK with hydrophobia, anxiety and confusion nine weeks after receiving a dog bite in North West India. Nuchal skin biopsy, saliva, and a skin biopsy from the site of the dog bite wound, taken on the day of admission, all demonstrated the presence of rabies virus RNA. Within 48 hours sequence analysis of viral RNA confirmed the diagnosis and demonstrated that the virus was a strain closely related to canine rabies viruses circulating in South Asia. Her condition deteriorated rapidly with increased agitation and autonomic dysfunction. She was heavily sedated and intubated on the day after admission, treated according to a modified Milwaukee protocol, and remained stable until she developed heart block and profound acidosis and died on the eighth day. Analysis of autopsy samples showed a complete absence of rabies neutralizing antibody in cerebrospinal fluid and serum, and corresponding high levels of virus antigen and nucleic acid in brain and cerebrospinal fluid. Quantitative PCR showed virus was also distributed widely in peripheral tissues despite mild or undetectable histopathological changes. Vagus nerve branches in the heart showed neuritis, a probable Negri body but no demonstrable rabies antigen.

CONCLUSION

Rapid molecular diagnosis and strain typing is helpful in the management of human rabies infection. Post-mortem findings such as vagal neuritis highlight clinically important effects on the cardiovascular system which are typical for the clinical course of rabies in humans. Management guided by the Milwaukee protocol is feasible within well-resourced intensive care units, but its role in improving outcome for canine-derived rabies remains theoretical.

Diagnosis, management and post-mortem findings of a human case of rabies imported into the United Kingdom from India: a case report

BACKGROUND

Human rabies infection continues to be a significant public health burden globally, and is occasionally imported to high income settings where the Milwaukee Protocol for intensive care management has recently been employed, with limited success in improving survival. Access to molecular diagnostics, pre- and post-mortem, and documentation of pathophysiological responses while using the Milwaukee protocol, can add useful insights for the future of rabies management.

CASE PRESENTATION

A 58-year-old British Asian woman was referred to a regional general hospital in the UK with hydrophobia, anxiety and confusion nine weeks after receiving a dog bite in North West India. Nuchal skin biopsy, saliva, and a skin biopsy from the site of the dog bite wound, taken on the day of admission, all demonstrated the presence of rabies virus RNA. Within 48 hours sequence analysis of viral RNA confirmed the diagnosis and demonstrated that the virus was a strain closely related to canine rabies viruses circulating in South Asia. Her condition deteriorated rapidly with increased agitation and autonomic dysfunction. She was heavily sedated and intubated on the day after admission, treated according to a modified Milwaukee protocol, and remained stable until she developed heart block and profound acidosis and died on the eighth day. Analysis of autopsy samples showed a complete absence of rabies neutralizing antibody in cerebrospinal fluid and serum, and corresponding high levels of virus antigen and nucleic acid in brain and cerebrospinal fluid. Quantitative PCR showed virus was also distributed widely in peripheral tissues despite mild or undetectable histopathological changes. Vagus nerve branches in the heart showed neuritis, a probable Negri body but no demonstrable rabies antigen.

CONCLUSION

Rapid molecular diagnosis and strain typing is helpful in the management of human rabies infection. Post-mortem findings such as vagal neuritis highlight clinically important effects on the cardiovascular system which are typical for the clinical course of rabies in humans. Management guided by the Milwaukee protocol is feasible within well-resourced intensive care units, but its role in improving outcome for canine-derived rabies remains theoretical.

Current and future trends in the prevention, treatment and control of rabies

Rabies remains a global zoonosis of major public health, agricultural and economic significance. Dogs are the major animal reservoirs in developing regions, wildlife maintain cycles of infection even in developed countries and new viral etiological agents continue to emerge. Nearly all human rabies cases are related directly to animal bite and thus, primary disease prevention requires minimization of suspected exposures. Once exposure occurs, modern prophylaxis entails immediate wound care, local infiltration of rabies immune globulin and parenteral administration of modern cell culture vaccines in multiple doses. Pre-exposure vaccination should occur in selected population groups at risk of occupational exposure. Historically, survival from fatal rabies by at least five human patients, vaccinated prior to the onset of clinical signs, signaled initial optimism as to the theoretical utility of medical intervention. Recently, the heroic recovery of an unvaccinated teenager from clinical rabies offers hope of future specific therapy. Canine rabies elimination is the key towards ultimate reduction of the disease burden, as first illustrated in developed countries. Implementation of oral vaccination in free-ranging carnivore hosts demonstrates the feasibility of disease abatement in particular wildlife populations, such as demonstrated in Europe and North America, with an enhanced need for application to developing countries in the Americas, Africa and Eurasia.

Rabies: still a uniformly fatal disease? Historical occurrence, epidemiological trends, and paradigm shifts

Rabies has the highest case fatality of any infectious disease. Pathobiological and clinical insights have questioned the assertion that death is inevitable after onset of acute encephalomyelitis. Relying upon national laboratory-based surveillance, we reviewed records of human rabies acquired in the United States during 1960-2009. Changes in the epidemiology of human rabies were notable, due to improved animal management, safer and more efficacious biologics, and revisions in prevention guidelines. Historically, domestic animals were the most important source of infection. Since the 1990s, more human cases were associated with rabid bats. Prior to 1980, postexposure prophylaxis failures were reported. After development of modern rabies immune globulin and vaccines, none occurred. Of 75 human cases identified, only four patients survived. Rabies remains an extremely high consequence zoonosis, but the disease is not uniformly fatal, per se. Rabies is essentially preventable when primary exposures are averted, or appropriate prophylaxis occurs before illness.

Immunovirological correlates in human rabies treated with therapeutic coma

A 37-year-old woman was admitted to hospital and over the next 5 days developed a progressive encephalitis. Nuchal skin biopsy, analyzed using a Rabies TaqMan(c) PCR, demonstrated rabies virus RNA. She had a history in keeping with exposure to rabies whilst in South Africa, but had not received pre- or post-exposure prophylaxis. She was treated with a therapeutic coma according to the "Milwaukee protocol," which failed to prevent the death of the patient. Rabies virus was isolated from CSF and saliva, and rabies antibody was demonstrated in serum (from day 11 onwards) and cerebrospinal fluid (day 13 onwards). She died on day-35 of hospitalization. Autopsy specimens demonstrated the presence of rabies antigen, viral RNA, and viable rabies virus in the central nervous system.

Survival after treatment of rabies with induction of coma

We report the survival of a 15-year-old girl in whom clinical rabies developed one month after she was bitten by a bat. Treatment included induction of coma while a native immune response matured; rabies vaccine was not administered. The patient was treated with ketamine, midazolam, ribavirin, and amantadine. Probable drug-related toxic effects included hemolysis, pancreatitis, acidosis, and hepatotoxicity. Lumbar puncture after eight days showed an increased level of rabies antibody, and sedation was tapered. Paresis and sensory denervation then resolved. The patient was removed from isolation after 31 days and discharged to her home after 76 days. At nearly five months after her initial hospitalization, she was alert and communicative, but with choreoathetosis, dysarthria, and an unsteady gait.

Human rabies in India: epidemiological features, management and current methods of prevention

In most endemic countries stray dogs are the main source of rabies infection in humans. In India 95-97% of rabies patients are infected by dogs. Most pet dogs do not regularly receive booster doses of vaccine. In Thailand, most rabies patients develop the disease within 1 month of exposure. Rabies immunoglobulin is costly and usually not available. So in India nervous tissue vaccine is commonly used--it is inexpensive and freely available despite frequent neurological complications. The cost of immunization by tissue culture vaccines may be reduced by nearly 60% by intradermal vaccination.

Rabies: the disease and the value of intensive care treatment

Rabies remains an incurable disease which is endemic in many parts of the world, particularly the Indian sub-continent. Strict muzzling orders in the latter part of the 19th century and today's modern quarantine laws have ensured the disease has remained eradicated from Britain. Isolated imported cases of human rabies do still occur and present a variety of problems for both nursing and medical staff. This article looks at the clinical features of the disease, the success in developing a potent yet safe vaccine and questions the value and justification in using an intensive care environment for rabid patients who are essentially suffering from a terminal illness.

Failure of interferon alfa and tribavirin in rabies encephalitis

OBJECTIVE

To test the effect of interferon alfa and tribavirin (ribavirin) in patients with rabies encephalitis.

DESIGN

An open trial of chemotherapy and intensive care in patients with early rabies.

SETTING

The intensive care unit of a Bangkok hospital.

PATIENTS

Four conscious men with clinical rabies encephalitis.

INTERVENTIONS

Rapid virological diagnosis of rabies. Treatment with intravenous and intraventricular injections of high doses of lymphoblastoid interferon alfa in three patients and tribavirin in one patient. Intensive care was given throughout.

MAIN OUTCOME MEASURES

Rabies infection confirmed by antigen detection and virus isolation. Rabies neutralising antibody and specific IgM sought in serum and cerebrospinal fluid. Interferon concentrations monitored before and during treatment in three patients.

RESULTS

Interferon alfa treatment produced high concentrations in serum and cerebrospinal fluid. All four patients died after 5 1/2 to 12 1/2 days of treatment with no evidence of virostatic or clinically beneficial effects from either treatment.

CONCLUSION

Interferon alfa treatment is not effective in rabies encephalitis. The use of tribavirin warrants further study, possibly combined with new therapeutic methods.

Massive necrosis of the brain in rabies

A young man developed virologically proved hydrophobic rabies three months after being scratched on the cheek by a bat in Northern Alberta. He became comatose after 8 days and died 5 weeks after vigorous therapy with immune globulin, interferon and Vidarabine, and excellent maintenance of oxygenation. Electroencephalographic deterioration was gradual. At postmortem examination, the brain showed widespread loss of nerve cells, mild diffuse inflammatory changes and no Negri bodies. The lesions of massive laminar necrosis of the cerebral cortex, total loss of Purkinje cells with preservation of the granule cell layer, and severe softening of the amygdala are attributed to direct viral action rather than to anoxia or brain swelling with respirator brain.

Cardiac involvement in human rabies. Case report

A case of human rabies with cardiac involvement and viral inclusion bodies in the heart is presented. The Negri bodies were found in the Schwann cells of the right epicardial atrium, with secondary mononuclear cells inflammation. In the myocardium, an interstitial edema, proliferation of Anitschkov and rare mononuclear inflammatory cells were seen. There was no relevant cardiovascular signs or symptoms. The rarity of histological descriptions of Negri bodies in the heart is stressed, as well as the importance of cardiac involvement as a potential complication for cases with life prolonged by intensive care units, or in the end-stages of the disease.

Pathology of rabies: a light- and electron-microscopical study with particular reference to the changes in cases with prolonged survival

Light- and electron-microscopical studies were conducted on necropsy material from six cases of rabies encephalitis including three with the unusual feature of surviving for over 14 days as a result of intensive medical care. This included administration of antiviral agents and interferon inducers and prevention of hypoxia by intermittent positive pressure ventilation. In all these cases, typical Negri bodies were demonstrated. Inflammatory reaction was absent or minimal. Unlike the cases with short survival where Negri bodies were infrequently seen and restricted mostly to the hippocampus, in cases with prolonged survival, they were present in large number, widely distributed throughout the grey matter of the brain. The associated inflammatory reaction in these cases, however, did not keep pace with the increase in number of inclusion bodies. Peripheral neuritis was observed in two of these cases, which also showed myelitis involving the cervical region and inflammation of dorsal root ganglia. One of them showed necrosis and severe inflammation of the lower cervical sympathetic ganglion. An electron-microscopical study conducted in four cases showed three forms of the inclusion body in the cytoplasm of neurons.

Epidemology and clinical aspects of human rabies in Minas Gerais, Brasil: misdiagnosis and misunderstandings on the psychopathological disturbances

This paper reports 40 cases of human rabies studied at the Carlos Chagas Hospital of UFMC, State of Minas Gerais, Brazil, from 1963 through 1976. From the epidemioiogical point of view it is concluded that the magnitude of the problem of human rabies in underdeveioped countries remains quite unknown. Speciai emphasis is given to the lack of apropriate knowledge of the recommended preventive measures, and to the influence of health education and socio-economic-cultural structure of the communities. The classic clinical picture of human rabies is briefiy described, particular attention being drawn to psychopathologic features of rabies encephalomyeiitis. it is pointed out that in some cases the mental symptoms may predominate from the onset of the illness, adding difficuity to the diagnosis. According to the Authors, human rabies must be differentiated from several psychopathologic syndromes and also from encephalomyelitis due to other central nervous system infections. It is discussed whether the fataiistic concept of human rabies would be somehow contributing to delay a better understanding of the natural history of the disease.

Recovery of immune responsiveness to rabies vaccine after treatment of mice with cyclophosphamide

Mice treated with cyclophosphamide (Cy) recovered the ability to mount delayed type hypersensitivity reactions within 3 days. By contrast, antibody production to a T cell independent antigen (E. coli lipopolysaccharide) and to human diploid cell strain rabies vaccine did not occur unless the immunization of Cy-treated mice was delayed for 7-10 days. No significant resistance to rabies infection was recorded at 10 days but was demonstrable if 14 days had elapsed between Cy treatment and vaccination.

Human rabies encephalomyelitis

Seven weeks after he was bitten on the lip by a puppy in the Gambia a patient showed symptons of rabies. Passive and active immunisation was begun three days after the onset of symptons. The evidence indicated that death was a direct consequence of the central nervous system disease rather than any associated complication. Our inability to alter the course of the illness appreciably emphasises the importance of immediate postexposure immunisation in rabies and draws attention to the present lack of effective means of preventing virus replication within the central nervous system.

A case of rabies in man: some problems in diagnosis and management

A patient who returned from India with a gastrointestinal disturbance subsequently developed the clinical features of rabies. The diagnosis was confirmed by isolation of rabies virus from saliva and the demonstration of rising titres of rabies antibody. He was treated in an intensive care unit, ventilated mechanically, and given rabies antiserum, but cerebral activity ceased and he died after 22 days. His course was marked by numerous bouts of cardiac arrhythmia including complete heart block. This case indicates the need for vaccination against rabies to be carried out immediately after exposure to a possibly rabid dog since encephalitis develops a fatal outcome may not be prevented even with intensive medical treatment.

Pathophysiologic studies in human rabies

Six patients with proved rabies were studied with a combination of clinical, physiologic and pathologic technics. Three were given a type of intensive care but died with evidence of respiratory failure. Although circulatory failure did not develop in any of the six patients, three had supraventricular arrhythmias: interstitial myocarditis was found in one of these and rabies virus was isolated from the myocardium of another. Inspiratory muscle spasm was the dominant clinical feature in all cases. This occurred as part of the hydrophobic response and followed stimulation of the upper respiratory tract and skin. Hydrophobia may represent an exaggerated respiratory tract irritant reflex with associated arousal. Later in the course of the disease, various patterns of periodic and ataxic breathing were observed. Widespread brain stem encephalitis was discovered at autopsy, with particular involvement of the neighborhood of the nucleus ambiguous in two of three patients examined. In one patient cerebral metabolism was grossly abnormal, with greatly reduced cerebral oxygen consumption suggesting irreversible brain damage. Respiratory and circulatory disturbances may well be immediate causes of death in patients with rabies, but the present studies reemphasize the severity of the encephalitis which remains the ultimate barrier to survival. In the developing countries in which rabies is still a major problem and in which the cost precludes intensive care, the clinical management of rabies can aim only to reduce suffering by heavy sedation.

The clinical picture of rabies in man

After an incubation period of one to two months rabies presents with non-specific prodromal symptoms and often with paraesthesiae of the bitten area. As in canine rabies there are furious and dumb forms of the disease. In man, furious rabies is characterised by hydrophobia: terror and excitation with spasms of inspiratory muscles, larynx and pharynx precipitated by attempts to drink and by a variety of other stimuli. Hydrophobia may represent an exaggerated respiratory tract irritant reflex with associated arousal potentiated by the selective destruction of brain stem inhibitory systmes. Also typical of furious rabies are intermittent episodes of excitement, hallucinations and maniacal behaviour. Focal neurological abnormalities are surprisingly uncommon. Other signs include hypersalivation, tachycardia and hyperpyrexia. Paralysis and coma supervene after a few days: survival rarely exceeds seven days. Dumb or paralytic rabies is an ascending flaccid paralysis with sphincter involvement and sensory disturbances. Death from respiratory and bulbar paralysis occurs after a longer illness than furious rabies. In a minority of cases hydrophobia develops before the terminal coma. Complications include respiratory arrest, pneumonitis, cardiac arrhythmias and interstitial myocarditis, posterior pituitary disorders, and gastrointestinal bleeding. Differential diagnoses of furious rabies include hysterical pseudo hydrophobia, tetanus, other encephalitides, delirium tremens and various other intoxications. Paralytic rabies may have to be distinguished from postvaccinal encephalomyelitis, poliomyelitis and other causes of Landry-type ascending paralysis. Intensive care has produced some promising results: life-threatening complications can be prevented but there is some evidence that the severity of the encephalitis is the ultimate barrier to survival.

Evaluation of the corneal test as a laboratory method for rabies diagnosis

The corneal test (CT) for rabies diagnosis was evaluated in samples from 313 subjects of different species. Some of the subjects were inoculated experimentally and others were naturally infected. When the CT was compared with immunofluorescence staining and mouse inoculation tests on brains of the same subjects, a sensitivity of 41.7% and a specificity of 100% were found. The authors conclude that a positive CT result would confirm the diagnosis of rabies, but a negative one would not exclude the possibility of disease.