Spread of adenovirus to geographically dispersed military installations, May-October 2007.

In mid-May 2007, a respiratory disease outbreak associated with adenovirus, serotype B14 (Ad14), was recognized at a large military basic training facility in Texas. The affected population was highly mobile; after the 6-week basic training course, trainees immediately dispersed to advanced training sites worldwide. Accordingly, enhanced surveillance and control efforts were instituted at sites receiving the most trainees. Specimens from patients with pneumonia or febrile respiratory illness were tested for respiratory pathogens by using cultures and reverse transcription-PCR. During May through October 2007, a total of 959 specimens were collected from 21 sites; 43.1% were adenovirus positive; the Ad14 serotype accounted for 95.3% of adenovirus isolates. Ad14 was identified at 8 sites in California, Florida, Mississippi, Texas, and South Korea. Ad14 spread readily to secondary sites after the initial outbreak. Military and civilian planners must consider how best to control the spread of infectious respiratory diseases in highly mobile populations traveling between diverse geographic locations.

Health care transmission of a newly emergent adenovirus serotype in health care personnel at a military hospital in Texas, 2007.

BACKGROUND: Adenoviruses can cause outbreaks of febrile respiratory illness in military trainees, but until 2007, adenovirus serotype 14 (Ad14) was never associated with such outbreaks. From April through June 2007, 15 trainees at one base were hospitalized for pneumonia due to Ad14. Subsequent reports of febrile respiratory illness among health care personnel suggested nosocomial transmission. METHODS: Health care personnel participants completed a questionnaire and provided blood and nasal wash specimens for Ad14 diagnostic testing. We defined a confirmed case of Ad14 infection as one with titers > or = 1:80 or nasal wash specimens positive for Ad14 by polymerase chain reaction, whereas a possible case was defined by titers of 1:20 or 1:40. We also collected environmental samples. RESULTS: Among 218 tested health care personnel, 35 (16%) had titers > or = 1:20; of these, 7 had possible cases and 28 had confirmed cases of infection. Confirmed case patients were more likely to report febrile respiratory illness (57% vs 11%; P< .001) and to have had direct contact with patients with Ad14 infection (82% vs 62%; P.04 ). Of the 23 confirmed case patients with direct contact with Ad14-infected patients, 52% reported that patients were not in contact and droplet precautions at the time of exposure. Ad14 was recovered from several hospital surfaces. CONCLUSION: Our findings of possible nosocomial transmission of Ad14 highlight the need to reinforce infection control guidelines.

Nipah virus infection in dogs, Malaysia, 1999.

The 1999 outbreak of Nipah virus encephalitis in humans and pigs in Peninsular Malaysia ended with the evacuation of humans and culling of pigs in the epidemic area. Serologic screening showed that, in the absence of infected pigs, dogs were not a secondary reservoir for Nipah virus.

Outbreak of severe respiratory disease associated with emergent human adenovirus serotype 14 at a US air force training facility in 2007.

BACKGROUND: In 2007, a US Air Force training facility reported a cluster of severe respiratory illnesses associated with a rare human adenovirus (Ad) serotype, Ad14. We investigated this outbreak to better understand its epidemiology, clinical spectrum, and associated risk factors. METHODS: Data were collected from ongoing febrile respiratory illness (FRI) surveillance and from a retrospective cohort investigation. Because an Ad7 vaccine is in development, Ad7 antibody titers in pretraining serum samples from trainees with mild and those with severe Ad14 illness were compared. RESULTS: During 2007, an estimated 551 (48%) of 1147 trainees with FRI were infected with Ad14; 23 were hospitalized with pneumonia, 4 required admission to an intensive care unit, and 1 died. Among cohort members (n = 173), the Ad14 infection rate was high (50%). Of those infected, 40% experienced FRI. No cohort members were hospitalized. Male sex (risk ratio [RR], 4.7 [95% confidence interval {CI}, 2.2-10.1]) and an ill close contact (RR, 1.6 [95% CI, 1.2-2.2]) were associated with infection. Preexisting Ad7 neutralizing antibodies were found in 7 (37%) of 19 Ad14-positive trainees with mild illness but in 0 of 16 trainees with Ad14 pneumonia (P = .007). CONCLUSIONS: Emergence of Ad14, a rare Ad serotype, caused a protracted outbreak of respiratory illness among military recruits. Most infected recruits experienced FRI or milder illnesses. Some required hospitalization, and 1 died. Natural Ad7 infection may protect against severe Ad14 illness.

DNA vaccination of the American crow (Corvus brachyrhynchos) provides partial protection against lethal challenge with West Nile virus.

The New York 1999 strain of West Nile virus (WNV) is nearly 100% fatal in the American crow (Corvus brachyrhynchos). We evaluated four WNV vaccine formulations in American crows, including intramuscular (i.m.) DNA vaccine, i.m. DNA vaccine with adjuvant, orally administered microencapsulated DNA vaccine, and i.m. killed vaccine. Neutralizing antibodies developed in approximately 80% of crows that received the DNA vaccine i.m. (with or without adjuvant), and in 44% that received the killed vaccine. However, no crows that received the oral microencapsulated DNA vaccine or the placebo developed WNV antibodies. All crows were challenged 10 wk after initial vaccination. No unvaccinated crows survived challenge, and survival rates were 44% (i.m. DNA vaccine), 60% (i.m. DNA vaccine with adjuvant), 0% (oral microencapsulated DNA vaccine), and 11% (killed vaccine). Peak viremia titers in the birds that survived were significantly lower as compared to titers in birds that died. Parenteral administration of a WNV DNA vaccine was associated with reduced mortality but did not provide sterile immunity.

West Nile virus quantification in feces of experimentally infected American and fish crows.

To better understand the potential environmental health risk presented by West Nile virus (WNV)-contaminated feces, we quantified the amount of WNV present in the feces of experimentally infected American crows (Corvus brachyrhynchos) and fish crows (Corvus ossifragus). Peak fecal titers ranged from 10(3.5) to 10(8.8) plaque-forming units (PFU)/g for 10 American crows and from 10(2.3) to 10(6.4) PFU/g for 10 fish crows. The presence of infectious WNV in bird feces indicates a potential for direct transmission of WNV. Thus, handlers of sick or dead birds should take appropriate precautions to avoid exposure to fecal material.

Serologic survey of cats and dogs during an epidemic of West Nile virus infection in humans.

OBJECTIVE: To estimate West Nile virus (WNV) infection rates, assess environmental variables that correlated with seropositivity in dogs and cats, and assess whether pets should be considered as possible sentinels for WNV and therefore of potential human exposure. DESIGN: Cross-sectional serosurvey. ANIMALS: 442 dogs and 138 cats. PROCEDURE: Serum samples were screened for seropositivity against WNV by use of the plaque reduction neutralization test. RESULTS: 116 (26%) dogs and 13 (9%) cats yielded positive results. The odds of seropositivity against WNV for outdoor-only family dogs were almost 19 times as great as those for indoor-only family dogs and almost twice as great for stray dogs as for family dogs. Family dogs not receiving heartworm medication were 2.5 times as likely to yield positive results for antibodies against WNV as family dogs receiving heartworm medication. CONCLUSIONS AND CLINICAL RELEVANCE: Seropositivity was greater for outdoor family dogs than for indoor family dogs. Further investigation of the potential use of stray dogs as sentinel indicators for WNV infection and the potential risk of human exposure is warranted.

Experimental infection of cats and dogs with West Nile virus.

Domestic dogs and cats were infected by mosquito bite and evaluated as hosts for West Nile virus (WNV). Viremia of low magnitude and short duration developed in four dogs but they did not display signs of disease. Four cats became viremic, with peak titers ranging from 10(3.0) to 10(4.0) PFU/mL. Three of the cats showed mild, non-neurologic signs of disease. WNV was not isolated from saliva of either dogs or cats during the period of viremia. An additional group of four cats were exposed to WNV orally, through ingestion of infected mice. Two cats consumed an infected mouse on three consecutive days, and two cats ate a single infected mouse. Viremia developed in all of these cats with a magnitude and duration similar to that seen in cats infected by mosquito bite, but none of the four showed clinical signs. These results suggest that dogs and cats are readily infected by WNV. The high efficiency of oral transmission observed with cats suggests that infected prey animals may serve as an important source of infection to carnivores. Neither species is likely to function as an epidemiologically important amplifying host, although the peak viremia observed in cats may be high enough to infect mosquitoes at low efficiency.

Isolated case of bioterrorism-related inhalational anthrax, New York City, 2001.

On October 31, 2001, in New York City, a 61-year-old female hospital employee who had acquired inhalational anthrax died after a 6-day illness. To determine sources of exposure and identify additional persons at risk, the New York City Department of Health, Centers for Disease Control and Prevention, and law enforcement authorities conducted an extensive investigation, which included interviewing contacts, examining personal effects, summarizing patient's use of mass transit, conducting active case finding and surveillance near her residence and at her workplace, and collecting samples from co-workers and the environment. We cultured all specimens for Bacillus anthracis. We found no additional cases of cutaneous or inhalational anthrax. The route of exposure remains unknown. All environmental samples were negative for B. anthracis. This first case of inhalational anthrax during the 2001 outbreak with no apparent direct link to contaminated mail emphasizes the need for close coordination between public health and law enforcement agencies during bioterrorism-related investigations.

Epitope-blocking enzyme-linked immunosorbent assays for detection of west nile virus antibodies in domestic mammals.

We evaluated the ability of epitope-blocking enzyme-linked immunosorbent assays (ELISAs) to detect West Nile virus (WNV) antibodies in domestic mammals. Sera were collected from experimentally infected horses, cats, and pigs at regular intervals and screened in ELISAs and plaque reduction neutralization tests. The diagnostic efficacies of these techniques were similar.

Laboratory response to anthrax bioterrorism, New York City, 2001.

In October 2001, the greater New York City Metropolitan Area was the scene of a bioterrorism attack. The scale of the public response to this attack was not foreseen and threatened to overwhelm the Bioterrorism Response Laboratory's (BTRL) ability to process and test environmental samples. In a joint effort with the Centers for Disease Control and Prevention and the cooperation of the Department of Defense, a massive effort was launched to maintain and sustain the laboratory response and return test results in a timely fashion. This effort was largely successful. The development and expansion of the facility are described, as are the special needs of a BTRL. The establishment of a Laboratory Bioterrorism Command Center and protocols for sample intake, processing, reporting, security, testing, staffing, and and quality control are also described.

Experimental infection of horses with West Nile virus.

A total of 12 horses of different breeds and ages were infected with West Nile virus (WNV) via the bites of infected Aedes albopictus mosquitoes. Half the horses were infected with a viral isolate from the brain of a horse (BC787), and half were infected with an isolate from crow brain (NY99-6625); both were NY99 isolates. Postinfection, uninfected female Ae. albopictus fed on eight of the infected horses. In the first trial, Nt antibody titers reached >1:320, 1:20, 1:160, and 1:80 for horses 1 to 4, respectively. In the second trial, the seven horses with subclinical infections developed Nt antibody titers >1:10 between days 7 and 11 post infection. The highest viremia level in horses fed upon by the recipient mosquitoes was approximately 460 Vero cell PFU/mL. All mosquitoes that fed upon viremic horses were negative for the virus. Horses infected with the NY99 strain of WNV develop low viremia levels of short duration; therefore, infected horses are unlikely to serve as important amplifying hosts for WNV in nature.