Cluster of five children with acute encephalopathy associated with cat-scratch disease in south Florida.

Between August 12 and September 27, 1994, five children in South Florida were hospitalized at a single hospital because of encephalopathy, presenting as status epilepticus, associated with cat-scratch disease (CSD). Diagnoses were confirmed by using an indirect fluorescent antibody test to detect antibody to Bartonella henselae, the causative agent of CSD. These cases represent the first cluster of CSD encephalopathy cases to be recognized in the United States. The patients lived within 7 miles of each other and all reported contact with pet or stray cats before developing regional lymphadenopathy and encephalopathy. All recovered fully. A high proportion of 124 cats from the local area were seropositive (62%) or bacteremic (22%). This study suggests that B. henselae can be associated with geographically focal clusters of CSD encephalitis and should be considered in the evaluation of children with acute encephalopathy.

Biological warfare training. Infectious disease outbreak differentiation criteria.

The threat of biological terrorism and warfare may increase as the availability of weaponizable agents increase, the relative production costs of these agents decrease, and, most importantly, there exist terrorist groups willing to use them. Therefore, an important consideration during the current emphasis of heightened surveillance for emerging infectious diseases is the capability to differentiate between natural and intentional outbreaks. Certain attributes of a disease outbreak, while perhaps not pathognomic for a biological attack when considered singly, may in combination with other attributes provide convincing evidence for intentional causation. These potentially differentiating criteria include proportion of combatants at risk, temporal patterns of illness onset, number of cases, clinical presentation, strain/variant, economic impact, geographic location, morbidity/mortality, antimicrobial resistance patterns, seasonal distribution, zoonotic potential, residual infectivity/toxicity, prevention/therapeutic potential, route of exposure, weather/climate conditions, incubation period, and concurrence with belligerent activities of potential adversaries.

Agroterrorism, biological crimes, and biowarfare targeting animal agriculture. The clinical, pathologic, diagnostic, and epidemiologic features of some important animal diseases.

In the past 100 years, to our knowledge there have been approximately 12 events involving the intentional introduction of microbiologic agents into livestock and animal populations worldwide, of which three were World War I events in the United States. To the best of the authors' knowledge, there has been no recent intentional introduction of microbiologic agents (viruses or bacteria) into livestock and animal populations in the United States. The criminal or terrorist use of chemicals against animals and agriculture products have been more common. With the political, economic, and military new world order, however, the United States must maintain a vigilant posture. The framework for this vigilance must be an intelligence system sensitive to the needs of agriculture and a first-class animal disease diagnostic surveillance and response system.

Rabies surveillance in the United States during 1995.

In 1995, 49 states, the District of Columbia, and Puerto Rico reported 7,877 cases of rabies in nonhuman animals and 4 cases in human beings to the Centers for Disease Control and Prevention. Nearly 92% (7,247 cases) were wild animals, whereas 8% (630 cases) were domestic species. The total number of reported cases decreased 4.2% from that of 1994 (8,230 cases). Most of the decline was the result of 17.1% fewer reported cases of rabies in raccoons in areas of the Northeast, where rabies is now enzootic rather than epizootic. Exceptions to this decline were detected in states where the virus has only recently entered raccoon populations or where ongoing epizootics persist. States experiencing increasing epizootic activity associated with this variant include Maine (3 cases in 1993 to 101 cases in 1995), North Carolina (9 cases in 1990 to 466 cases in 1995), Rhode Island (1 case in 1993 to 324 cases in 1995), and Vermont (45 cases in 1993 to 179 cases in 1995). The raccoon variant of the rabies virus is now present in Alabama, Pennsylvania, Vermont, West Virginia, and all Atlantic Seaboard states from Florida to Maine. In Ohio, this variant, last detected in 1992 as a single case, was again detected in 1996. Epizootics of rabies in foxes in west central Texas and in dogs and coyotes in southern Texas attributable to canine variants continue, with this state reporting 137 rabid foxes, 55 rabid dogs, and 80 of the 83 cases in coyotes during 1995. The number of rabid bats (787) increased by almost 25%, with cases reported by 47 of the 48 contiguous states. Nationally, reported cases of rabies in cattle (136) and cats (288) increased by 22.5 and 7.9%, respectively, whereas cases in dogs (146) decreased by 4.6%. Cats continued to be the domestic animal most frequently reported rabid. The cases of rabies reported in human beings were all caused by viral variants associated with bats. Eighteen states and Puerto Rico reported decreases in rabies in animals in 1995, compared with 28 states and the District of Columbia in 1994. Hawaii was the only state that did not report a case of rabies in 1995.

Survey of veterinary professionals and other veterinary conference attendees for antibodies to Bartonella henselae and B quintana.

OBJECTIVE: To determine serologic and epidemiologic characteristics of an occupational group potentially at risk for Bartonella sp infection. DESIGN: Epidemiologic survey. SAMPLE POPULATION: 351 veterinarians, veterinary technicians, and other individuals attending a veterinary conference in Ohio. PROCEDURE: A serum sample was obtained from each individual and tested for antibodies to Bartonella henselae or B quintana. A 24-question survey also was administered regarding demographic, occupational, and exposure information. RESULTS: 25 (7.1%) individuals were seropositive for B henselae or B quintana. Forty-seven, of whom 5 were seropositive, reported a history of illness consistent with cat-scratch disease and 18, of whom 3 were seropositive, reported a previous diagnosis of cat-scratch disease. Of the variables analyzed, only years of experience with cats was correlated with seropositivity. CLINICAL IMPLICATIONS: The overall seroprevalence for 2 species of Bartonella in this occupational group was only slightly higher than that reported from other surveys. Seroprevalences among veterinarians, veterinary technicians, hospital staff, and others were essentially identical. Small sample groups, high percentage of cat ownership among participants, unknown duration of seropositivity, and unknown prevalence of infection among cats were potential confounders.

Biological warfare training: infectious disease outbreak differentiation criteria.

The threat of biological terrorism and warfare may increase as the availability of weaponizable agents increases, the relative production costs of these agents decrease, and, most importantly, there exist terrorist groups willing to use them. Therefore, an important consideration during the current period of heightened surveillance for emerging infectious diseases is the ability to differentiate between natural and intentional outbreaks. Certain attributes of a disease outbreak, although perhaps not pathognomonic for a biological attack when considered singly, may combine to provide convincing evidence of intentional causation. These potentially differentiating criteria include proportion of combatants at risk, temporal patterns of illness onset, number of cases, clinical presentation, strain/variant, economic impact, geographic location, morbidity/mortality, antimicrobial resistance patterns, seasonal distribution, zoonotic potential, residual infectivity/toxicity, prevention/therapeutic potential, route of exposure, weather/climate conditions, incubation period, and concurrence with belligerent activities of potential adversaries.

Meeting the challenge of emerging pathogens: the role of the United States Air Force in global influenza surveillance.

Influenza virus is one of the most ubiquitous organisms on the planet, causing illness in much of the population each year. The dynamic nature of the influenza virus requires similarly dynamic surveillance and prevention initiatives. The efforts of national surveillance programs, overseen by the World Health Organization and administered by institutions such as the U.S. Centers for Disease Control and Prevention, the U.S. armed forces, and 60 to 70 collaborating laboratories, annually culminate in the development of effective influenza vaccines. The U.S. Air Force's contribution is via Project Gargle, through which bases in various locations worldwide conduct active surveillance and submit throat swab specimens for virus isolation and characterization; the results of these laboratory analyses help determine the composition of the following year's influenza vaccine. These collaborative efforts have resulted in an identical or close antigenic match between vaccine and epidemic strains in 8 of the last 9 influenza seasons.

Interferon regulatory factor 3 is required for viral induction of beta interferon in primary cardiac myocyte cultures.

Viral myocarditis affects an estimated 5 to 20% of the human population. The antiviral cytokine beta interferon (IFN-beta) is critical for protection against viral myocarditis in mice. That is, nonmyocarditic reoviruses induce myocarditis in mice that lack IFN-alpha/beta, and nonmyocarditic reoviruses both induce more IFN-beta and are more sensitive to the antiviral effects of IFN-beta than myocarditic reoviruses in primary cardiac myocyte cultures. Induction of IFN-beta in certain cell types involves viral activation of the transcription factor interferon regulatory factor 3 (IRF-3). To address whether IRF-3 can induce IFN-beta in cardiac myocytes, primary cardiac myocyte cultures and control L929 cells were transfected with a plasmid constitutively expressing IRF-3. Overexpression of IRF-3 resulted in induction of IFN-beta in the absence of viral infection in both cell types. To address whether IRF-3 is required for viral induction of IFN-beta, cell cultures were transfected with a plasmid constitutively expressing a dominant negative IRF-3 protein. The dominant negative IRF-3 reduced reovirus induction of IFN-beta in control L929 cells and completely eliminated induction in primary cardiac myocyte cultures. This provides the first identification of a cardiac cellular factor required for viral induction of IFN-beta and the first report of any cell type requiring IRF-3 for this response.

The reovirus protein mu2, encoded by the M1 gene, is an RNA-binding protein.

The reovirus M1, L1, and L2 genes encode proteins found at each vertex of the viral core and are likely to form a structural unit involved in RNA synthesis. Genetic analyses have implicated the M1 gene in viral RNA synthesis and core nucleoside triphosphatase activity, but there have been no direct biochemical studies of mu2 function. Here, we expressed mu2 in vitro and assessed its RNA-binding activity. The expressed mu2 binds both poly(I-C)- and poly(U)-Sepharose, and binding activity is greater in Mn2+ than in Mg2+. Heterologous RNA competes for mu2 binding to reovirus RNA transcripts as effectively as homologous reovirus RNA does, providing no evidence for sequence-specific RNA binding by mu2. Protein mu2 is now the sixth reovirus protein demonstrated to have RNA-binding activity.

Efficient translation of mRNAs in influenza A virus-infected cells is independent of the viral 5' untranslated region.

We test the hypothesis that the translation machinery in cells infected by influenza A virus efficiently translates only mRNAs that possess the influenza viral 5' untranslated region (5'-UTR) by introducing mRNAs directly into the cytoplasm of infected cells. This strategy avoids effects due to the inhibition of the nuclear export of cellular mRNAs mediated by the viral NS1 protein. In one approach, we transfect in vitro synthesized mRNAs into infected cells and demonstrate that these mRNAs are efficiently translated whether or not they possess the influenza viral 5'-UTR. In the second approach, an mRNA is synthesized endogenously in the cytoplasm of influenza A virus infected cells by a constitutively expressed T7 RNA polymerase. Although this mRNA is uncapped and lacks the influenza viral 5'-UTR sequence, it is efficiently translated in infected cells via an internal ribosome entry site. We conclude that the translation machinery in influenza A virus infected cells is capable of efficiently translating all mRNAs and that the switch from cellular to virus-specific protein synthesis that occurs during infection results from other processes.

Mass human exposure to rabies in New Hampshire: exposures, treatment, and cost.

OBJECTIVES: This study assessed the rabies exposure and treatment that at least 665 persons in Concord, NH, received as a result of one proven rabid pet-store kitten in October 1994. METHODS: All treatment recipients were interviewed by person or phone. RESULTS: The median age of the treatment recipients was 14 years; 58% were female. The most common exposures were low risk (e.g., picking up, petting, nuzzling, or being scratched by a potentially rabid kitten). Local reactions to vaccine or immune globulin were reported by 76.5% of recipients, while 48.8% reported at least one systemic reaction. Cost for the biologicals was estimated at more than $1.1 million. CONCLUSIONS: Because of the inadequacy of pet store records, the inconsistent application of treatment guidelines, and other factors, many people received postexposure treatment as a result of contacts that were unlikely to transmit rabies. The rates of local and systemic adverse reactions experienced were consistent with previous reports.

Ebola hemorrhagic fever, Kikwit, Democratic Republic of the Congo, 1995: risk factors for patients without a reported exposure.

In 1995, 316 people became ill with Ebola hemorrhagic fever (EHF) in Kikwit, Democratic Republic of the Congo. The exposure source was not reported for 55 patients (17%) at the start of this investigation, and it remained unknown for 12 patients after extensive epidemiologic evaluation. Both admission to a hospital and visiting a person with fever and bleeding were risk factors associated with infection. Nineteen patients appeared to have been exposed while visiting someone with suspected EHF, although they did not provide care. Fourteen of the 19 reported touching the patient with suspected EHF; 5 reported that they had no physical contact. Although close contact while caring for an infected person was probably the major route of transmission in this and previous EHF outbreaks, the virus may have been transmitted by touch, droplet, airborne particle, or fomite; thus, expansion of the use of barrier techniques to include casual contacts might prevent or mitigate future epidemics.

Chronic multisymptom illness affecting Air Force veterans of the Gulf War.

CONTEXT: Gulf War (GW) veterans report nonspecific symptoms significantly more often than their nondeployed peers. However, no specific disorder has been identified, and the etiologic basis and clinical significance of their symptoms remain unclear. OBJECTIVES: To organize symptoms reported by US Air Force GW veterans into a case definition, to characterize clinical features, and to evaluate risk factors. DESIGN: Cross-sectional population survey of individual characteristics and symptoms and clinical evaluation (including a structured interview, the Medical Outcomes Study Short Form 36, psychiatric screening, physical examination, clinical laboratory tests, and serologic assays for antibodies against viruses, rickettsia, parasites, and bacteria) conducted in 1995. PARTICIPANTS AND SETTING: The cross-sectional questionnaire survey included 3723 currently active volunteers, irrespective of health status or GW participation, from 4 air force populations. The cross-sectional clinical evaluation included 158 GW veterans from one unit, irrespective of health status. MAIN OUTCOME MEASURES: Symptom-based case definition; case prevalence rate for GW veterans and nondeployed personnel; clinical and laboratory findings among veterans who met the case definition. RESULTS: We defined a case as having 1 or more chronic symptoms from at least 2 of 3 categories (fatigue, mood-cognition, and musculoskeletal). The prevalence of mild-to-moderate and severe cases was 39% and 6%, respectively, among 1155 GW veterans compared with 14% and 0.7% among 2520 nondeployed personnel. Illness was not associated with time or place of deployment or with duties during the war. Fifty-nine clinically evaluated GW veterans (37%) were noncases, 86 (54%) mild-to-moderate cases, and 13 (8%) severe cases. Although no physical examination, laboratory, or serologic findings identified cases, veterans who met the case definition had significantly diminished functioning and well-being. CONCLUSIONS: Among currently active members of 4 Air Force populations, a chronic multisymptom condition was significantly associated with deployment to the GW. The condition was not associated with specific GW exposures and also affected nondeployed personnel.

Epidemiology of human rabies in the United States, 1980 to 1996.

PURPOSE: To summarize the epidemiologic, diagnostic, and clinical features of the 32 laboratory-confirmed cases of human rabies diagnosed in the United States from 1980 to 1996. DATA SOURCES: Data were obtained from case reports of human rabies submitted to the Centers for Disease Control and Prevention by state or local health authorities. STUDY SELECTION: All cases of human rabies reported in the United States from 1980 to 1996 in which infection with rabies virus was confirmed by laboratory studies. DATA EXTRACTION: Patients were reviewed for demographic characteristics, exposure history, rabies prophylaxis, clinical presentation, treatment, clinical course, diagnostic laboratory tests, identification of rabies virus variants, and the number of medical personnel or family members who required postexposure prophylaxis after coming in contact with an exposed person. DATA SYNTHESIS: 32 cases of human rabies were reported from 20 states. Patients ranged in age from 4 to 82 years and were predominantly male (63%). Most patients (25 of 32) had no definite history of an animal bite or other event associated with rabies virus transmission. Of the 32 cases, 17 (53%) were associated with rabies virus variants found in insectivorous bats, 12 (38%) with variants found in domestic dogs outside the United States, 2 (6%) with variants found in indigenous domestic dogs, and 1 (3%) with a variant found in indigenous skunks. Among the 7 patients with a definite exposure history, 6 cases were attributable to dog bites received in foreign countries and 1 was attributable to a bat bite received in the United States. In 12 of the 32 patients (38%), rabies was not clinically suspected and was diagnosed after death. In the remaining 20 cases (63%), the diagnosis of rabies was considered before death and samples were obtained specifically for laboratory confirmation a median of 7 days (range, 3 to 17 days) after the onset of clinical signs. Of the clinical differences between patients in whom rabies was diagnosed before death and those in whom it was diagnosed after death, the presence of hydrophobia or aerophobia was significantly associated with antemortem diagnosis (odds ratio, 11.0 [95% CI, 1.05 to 273.34]). The median number of medical personnel or familial contacts of the patients who received postexposure prophylaxis was 54 per patient (range, 4 to 179). None of the 32 patients with rabies received postexposure prophylaxis before the onset of clinical disease. CONCLUSIONS: In the United States, human rabies is rare but probably underdiagnosed. Rabies should be included in the differential diagnosis of any case of acute, rapidly progressing encephalitis, even if the patient does not recall being bitten by an animal. In addition to situations involving an animal bite, a scratch from an animal, or contact of mucous membranes with infectious saliva, postexposure prophylaxis should be considered if the history indicates that a bat was physically present, even if the person is unable to reliably report contact that could have resulted in a bite. Such a situation may arise when a bat bite causes an insignificant wound or the circumstances do not allow recognition of contact, such as when a bat is found in the room of a sleeping person or near a previously unattended child.