Darwin Chronicles

March 2006

Inhalation anthrax exposure ruled accidental

Federal and state public health officials continue to investigate the case of a 44-year-old New York City man who was hospitalized in Pennsylvania after he fell ill from inhalation anthrax. It appears to be an isolated incident, they said, and was not due to an intentional exposure.

The last U.S. case of naturally occurring inhalation anthrax was in 1976, and was associated with a person who made wool rugs, according to Lisa Rotz, MD, medical epidemiologist at the CDC.

However, several anthrax cases occurred in 2001 that were related to an intentional spread of disease by letters mailed through the U.S. Postal Service. New York was one of the areas affected, so naturally, public health officials were concerned when the case was first reported. “The appearance of even an isolated case of anthrax understandably produces anxiety,” said Michael R. Bloomberg, mayor of New York, in a press conference. “There is no evidence that this is anything other than an accidental, isolated case that we are dealing with here.”

Public health officials interviewed the man, his wife and several colleagues and friends before concluding that the case was accidental. “We always go into these investigations with an open mind, but we have good health authorities in New York and Pennsylvania that have been diligent about tracking down additional information from the patient and from contacts with the patient,” said Rotz. “And right now we’re going with the information they have that leads us to believe that the gentleman that handled these animal hides that [they] could have been carrying spores, and that’s a leading hypothesis at that time.”

The patient had a history of contact with unprocessed animal hides, and he recently purchased unprocessed hides in Africa, which were then transported to New York, to make traditional African drums.

“He was doing a traditional form of artistic expression, with traditional African drums, traditionally made [for] traditional performances, and he got his anthrax in a traditional, but unfortunate, way,” explained Thomas R. Frieden, MD, commissioner of the New York City Department of Health and Mental Hygiene.

Caused by Bacillus anthracis, anthrax most commonly occurs in wild and domestic animals, such as cattle, sheep, goats, camels and antelopes. However, it can also occur in humans who are exposed to infected animals or untreated animal hides or wool. The disease used to be called woolsorter’s disease because it occurred in factories that processed wool.

“It’s my understanding that spores can reside within the hairs of hides of animals, especially in areas where anthrax is endemic in the soil,” Rotz said during a press conference. “My understanding — and I’m not a drum maker — from what I’ve been told, is that the process of drum making with these animal hides involves soaking the hide and then stretching it and doing a lot of scraping of the hide to remove the hair, which is potentially a scenario where he could aerosolize any spores that might have been on the hides.”

Environmental tests of the patient’s apartment in Greenwich Village, his storage and work facility in Brooklyn and a vehicle used by the patient indicated the presence of anthrax spores in all three locations, according to Bloomberg. In addition, the home of a colleague, who also made drums with unprocessed hides, was tested, but results were not yet available. Seven people, including the colleague and his family, received antibiotic prophylaxis, but did not show signs of being infected, according to Bloomberg. In addition, police raided the home of a third man who may have sold hides to the colleague.

The index patient was performing at Mansfield University in Tioga County, Pennsylvania, when he became ill and was hospitalized. The man poses no public health threat of transmitting anthrax to the community or the health care providers caring for him. Bloomberg said that the areas that tested positive are being cleaned by public health officials and officials from the Environmental Protection Agency.

The man performed in late February as part of Kotchegna, a dance company, which appeared in Pennsylvania. After leaving the performance, the man collapsed and was taken to a local hospital. On Feb. 17, blood tests were taken and by Feb. 20, the tests began to indicate the possible presence of anthrax. The hospital notified Pennsylvania DOH, and a sample was sent to the Pennsylvania DOH laboratory for further testing. On Feb. 21, the laboratory tests detected anthrax spores and a public health investigation began. Because the man is from New York, the DOH notified the New York City DOH, the CDC and the FBI. — Marie Rosenthal

WNV surveillance programs well developed in the U.S.

A federal survey found that West Nile virus (WNV) surveillance, prevention and control programs are well developed, but vary among state and city/county health departments because of differences in responsibilities.

“Survey findings also demonstrated that WNV surveillance, prevention and control programs in the six city/county health departments generally were well developed, with features including outreach to specialists, reporting of equine neurologic disease, tracking of dead-bird sightings, collection of mosquito infection rates, reporting of intervals from collection of human specimens to laboratory confirmation to surveillance program (median: 5.5 days) and testing for human infection. However, emphasis on different components of WNV surveillance, prevention and control programs varied between state health departments and city/county health departments because of differences in roles and responsibilities. For example, local agencies and contractors primarily conducted mosquito control; local health departments more frequently conducted larval (100% vs. 30%) and adult (100% vs. 48%) mosquito surveillance than state health departments. Local health departments also more frequently provided public notification of adulticiding activities (83% vs. 27%),” the CDC wrote in its report.

Since the first case was reported in August 1999 in New York, human WNV cases have been reported in all states except Alaska, Hawaii and Washington. From 1999 to 2005, the United States saw 19,525 cases of WNV human disease and 771 deaths. The virus is transmitted to humans by mosquito bites, blood transfusions, organ transplantation and breast-feeding; maternal to fetal transmission can also occur, according to the report, which appeared in the Morbidity and Mortality Weekly Report (2006;55[RR-6]:150-153).

The CDC created ArboNET for electronic surveillance, and eventually, surveillance was expanded to all 50 states, six cities/counties and Puerto Rico.

In 2005, the Council of State and Territorial Epidemiologists, with assistance from the Association of Public Health Laboratories and the CDC, surveyed these WNV programs to assess human, avian, equine and mosquito WNV infection; disease surveillance; laboratory capacity; and prevention activities. Forty-nine (98%) states and all six city/county health departments responded to the survey, which primarily asked questions about their 2004 programs.

The survey found:

• Forty (82%) of 49 states reported contact with infectious disease specialists to encourage disease reporting; 29 (60%) reported contacting neurologists; and 28 (57%) reported contacting critical care specialists;
• Thirty-one (63%) and 27 (55%) states, respectively, required reporting of encephalitis and meningitis cases of unknown etiology requiring hospitalization. Thirty-two (67%) states have a laboratory system to test cerebrospinal fluid specimens for arboviral infection;
• Forty-five states (92%) reported adequate access to wildlife biology experts and 40 (82%) had access to a designated state public health veterinarian;
• Forty-six (94%) reported that they either conducted mosquito surveillance themselves and/or collected information about mosquito surveillance conducted by other agencies in their areas;
• Nearly 62% of each state’s jurisdiction was reported covered by mosquito surveillance;
• Forty-one (84%) states had surveillance systems that included reporting of equine neurologic disease, 28 (57%) tracked dead-bird sightings and 36 (80%) collected information about mosquito infection rates by species; and
• Forty-one (87%) reported that their public health laboratories had biosafety level 3 capability in 2004.

“These findings illustrate the presence of well-developed WNV surveillance and control programs for human, avian, equine or mosquito populations within state and local health departments,” the CDC wrote.

Human antiviral being used to prevent canine influenza in dogs

Experts are concerned because of reports that veterinarians are using the human antiviral drug oseltamivir (Tamiflu, Roche) to prevent canine influenza in dogs.

“Tamiflu is very controversial to use in dogs because we just don’t know that much about it and if it even works in dogs,” said Cynda Crawford, DVM, veterinary immunologist at the University of Florida College of Veterinary Medicine, who was among the researchers who identified the canine influenza virus.

Crawford wanted to conduct studies on the drug to see if it would benefit dogs infected with canine influenza virus, but the project was postponed because of the growing demand to stockpile the drug for humans in case of an H5N1 avian influenza pandemic.

In addition to treating dogs for canine influenza, Crawford said that veterinarians have been known to use the drug as an ancillary treatment for puppies with parvovirus infection and distemper and for cats with calicivirus infections.

Canine influenza is an upper respiratory track disease first reported in racing greyhounds at a Florida racetrack. To date, antibodies have been detected in dogs in animal shelters, adoption groups, pet stories, boarding kennels and veterinary clinics in 19 states. The viral disease, which appears in mild or severe forms, is an H3N8 influenza that is closely related to equine influenza.

Treatment of canine influenza in dogs is largely supportive. In the mild form of the disease, a thick, green nasal discharge most likely represents a secondary bacterial infection that usually resolves quickly after treatment with a broad-spectrum antimicrobial. Pneumonia in more severely affected dogs responds best to a combination of broad-spectrum antimicrobials to combat secondary bacterial infections and maintenance of hydration from IV administration of fluids, according to the American Veterinary Medicine Association.

In other canine flu news, the University of California, Davis reported that a new test with a speedier, more accurate diagnosis of canine flu is now available to veterinarians throughout California.

The new test technology, based on polymerase chain reaction, provides results within 24 to 48 hours, according to researcher Christian Leutenegger, DVM, PhD, who created the test at the School of Veterinary Medicine.

“By analyzing the RNA collected on a swab from the dog’s throat, this test provides the quickest and most accurate test for canine influenza now available,” Leutenegger said in a release. “We have alerted veterinarians throughout California that the test is available.”

Swab samples should be taken within 72 hours after the dog exhibits symptoms of illness. Prior to this test, veterinarians used serum antibody tests to diagnose the disease, which relies on the production of sufficient antibodies to the virus to be detected, which delays diagnosis.

Because this is an emerging virus, dogs have no natural immunity to it. All dogs exposed will become infected and 80% will develop symptoms, similar to kennel cough, but may also have a thick nasal discharge. In severe cases, dogs may develop high fevers and pneumonia. The disease, which is transmitted by exposure to infectious droplets, kills 5% to 8% of infected dogs.

Equine herpes virus outbreak spreads to Kentucky

After unsuccessful attempts to stem outbreaks of equine herpes virus type 1 (EHV-1), Kentucky officials said that all horses coming onto a racetrack or training facility must have proof of recent vaccination for EHV-1.

Horses must have a valid Certificate of Veterinary Inspection, which records a horse’s health and condition, and that inspection certificate must be presented when a horse leaves the grounds. In addition, horses from affected barns can train on the grounds, but they must be segregated from other horses. Temperatures from all horses stabled on the tracks must be taken at lease twice daily with the results written in the certificate of inspection.

Horses from several tracks and stables in both Kentucky and Maryland have been euthanized or quarantined. “The bigger part of the risk is close contact of horses to each other and shared equipment, bridles and bits and things like that. And the people, somebody who handles the sick horse and then another horse, the high-risk activities,” Guy Hohenhaus, DVM, state veterinarian for the Maryland Department of Agriculture, explained at a press conference.

EHV-1 causes rhinopneumonitis, an upper respiratory disease, but it can also cause more serious neurological disease. Although vaccine is available, it requires frequent boosters to be effective.

“A good vaccine generally protects a large percentage of the people or animals that are vaccinated with it, but it [is] by no means 100%, and there are lots of reasons a vaccine fails. In this case, this is not an ideal vaccine. Most are helpful. Horses that are vaccinated every three to four months tend to have less disease. A horse that is five to six months away from its last vaccination is not much different than a horse that was never vaccinated,” Hohenhaus said.

Maryland recently lifted restrictions for Pimlico, when 43 horses in two barns finally tested negative for the EHV-1 by both PCR and virus isolation tests. As Infectious Disease News was going to press, however, restrictions were still in place for Laurel Park and Kent County Farm, according to Hohenhaus. — Marie Rosenthal

Scale insect attacks over 300 species of plants

One of the most menacing newcomers to Florida is the lobate lac scale (Paratachardina lobata), an insect native to India and Sri Lanka that attacks more than 300 types of woody plants, said Forrest Howard, PhD, associate professor of entomology at the University of Florida’s Institute of Food and Agricultural Sciences.

“No bigger than a pinhead, the insect could become the most difficult problem yet for trees and shrubs grown as ornamentals in urban areas and native plants in natural areas in South Florida,” he said in a release.

Howard said lobate lac scale probably arrived on a living plant. The scales are tiny and colored to blend with the plant, thereby escaping the eyes of agricultural inspectors at a port of entry.

“In 1999 when we first identified the insect in Broward County, we found it on about 10 different kinds of plants in a small area,” he said. “As it continued to spread across South Florida, we have now identified more than 300 species of woody plants that the lobate lac scale attacks.”

These include native species such as wax myrtle, cocoplum, red bay, wild coffee and strangler fig as well as commercial fruit trees such as mango, lychee and star fruit.

Howard and colleagues reported several highly effective insecticide treatments that protect plants from this scale. However, biological control offers the best long-term solution to the scale problem, but the host range of the beneficial predators must be determined to make sure they will attack nothing but the lobate lac scale, according to Howard. He along with other agencies is working to develop a biological control.