Darwin Chronicles

August 2006

Military reorganization needed for malaria vaccine, IOM says

Current efforts spread between the Army and the Navy to develop a malaria vaccine for the military need to be combined to be successful, according to a report from the Institute of Medicine.

Myron Levine, MD, director of the Center for Vaccine Development at the University of Maryland School of Medicine, said the military need to shift its focus to a business philosophy. Levine chaired the report committee and was one of the co-editors of Battling Malaria: Strengthening the U.S. Military Vaccine Program.

“They need to have a very specific broad goal and they need to be given more. They need to have a focus,” Levine said in an interview. “They currently have many, many potatoes in the fire, and no company or government unit working on vaccines would be able to support so many parallel projects at the same time.

“It’s very hard to kill your baby on a science project, but if you don’t then you effectively ensure that there’s a withering of all the projects because there’s not enough water, sun and fertilizer for all of them,” he said.

The United States Military had asked the Institute of Medicine to develop a plan for the delivery of a working vaccine by 2015, but Levine said that was an unrealistic goal.

“No approach other than attenuated sporozoites could have a licensed vaccine by 2015,” Levine said. “However, with the changes in the organization we recommend, a significant input in resources, and a lot of luck, a workable vaccine could be in place by 2020. In the world of vaccine development, that is not a long time.”

Malaria risk

According to the report, malaria has affected almost all military deployments since the American Civil War. Current prevention methods for malaria, such as repellents or mosquito nets, are inadequate.

In Liberia in 2003, 80 marines (28%) who spent a brief period ashore were affected by malaria and half of them had to be evacuated by air to Germany. This costly development prompted the military to step up its effort toward developing a vaccine, according to the report.

Malaria vaccine research and development is currently being carried out at the Walter Reed Army Institute of Research, the Naval Medical Research Center and at Department of Defense overseas laboratories in Kenya, Thailand, Indonesia, Peru and Egypt.

In addition to the recommendation that these efforts be consolidated, the report recommends that the Department of Defense continue its three-pronged research approach. Specifically, researchers should continue their work in gene-based, protein-based and attenuated sporozoite approaches. “However, as research progresses, the number of candidate products must be limited by dropping those that perform less well,” the researchers wrote in the report.

Levine said that research leaders should recognize that vaccine development research is a long-term process. – Jeremy Moore

Spreading disease from pets to people

Animals can spread a wide range of bacterial, viral, fungal and parasitic diseases to people, including Salmonella, West Nile Virus, Hantavirus, severe acute respiratory syndrome (SARS), rabies and avian flu.

According to Terry Yamauchi, MD, who spoke at the Association for Professionals in Infection Control and Epidemiology (APIC) meeting, this is a worldwide problem with worldwide consequences. “Arkansas has a large poultry industry and is also home to Wal-Mart Corporation, which lands three flights a day directly from China carrying imported goods and people, many of which come from the regions that have experienced avian flu outbreaks,” he noted.

“In China, officials are attempting to immunize 5 billion birds to cover the birds that are sold commercially. Farmers are feeding their birds Tamiflu, and a new strain of avian flu is emerging,” said Yamauchi, who is professor of pediatrics at the University of Arkansas for Medical Sciences in Little Rock.

He also said that in China, people other than farmers keep chickens as pets. “Many of these people are part of a subculture that raises fighting chickens. Trainers revive their chickens during or after a fight by sucking their wounds, and these people are at high risk for contracting avian flu,” he explained.

In the United States, approximately 58% of the population owns a pet. The pet population includes 62 million dogs, 69 million cats, 10 million birds and 3 million reptiles, with iguanas as the most popular reptilian pet.

Yamauchi became interested in the spread of disease from animals to humans nearly 30 years ago. A corporation that offered to donate tennis shoes to Arkansas Children’s Hospital asked if it could bring its kangaroo mascot to the hospital as part of the donation presentation. This request made him realize that there was not enough information available about potential spread of disease to humans from animals. Later, the local zoo received two new tiger cubs and wanted to bring them into the hospital for the sick children to see. Again, he wondered what diseases the tigers could carry and if they were transmittable to people.

As a result of these requests, Yamauchi began to evaluate the benefits of therapy using animals in a hospital setting. It was difficult to measure objectively the benefits of having sick patients interact with animals as Arkansas state law prohibited animals other than service animals in the hospital.

Risks vs. benefits

Although it has been shown that elderly adults experience a decrease in blood pressure when interacting with animals, the safety of all patients needs to be taken into consideration. For example, some patients may be allergic to animal dander, and in these patients the psychological benefits may not outweigh the physical consequences.

To determine objectively which diseases may be present in animals, Yamauchi conducted a study on animals at a local zoo. “A variety of bacteria types were found on all of the animals, except for the tarantula, and this may have been due to the tarantula’s dry, hot environment. In the literature, studies have shown that keratoconjunctivitis can be contracted from the hairs a tarantula sheds. Additionally, when the animals’ cages and water tanks were tested, bacteria were found to be present. Interestingly, the animals that were negative for Salmonella at the zoo were found to be positive for Salmonella after being transported to the hospital. Veterinarians suggest this is caused by stress,” he said.

He also cultured dogs and cats and found that 3% of dogs and cats had methicillin-resistant Staphylococcus aureus (MRSA). In addition, 10% of dogs and cats were carrying group A streptococcus. These tests were conducted approximately 15 years ago and were received with skepticism by the medical community, he added.

During the past decade, however, there has been an increased incidence of MRSA, so Yamauchi repeated his study of dogs and cats and found that 16% of dogs and cats had MRSA. “This is a rate that is similar to the rate in the human community. However, the link between these statistics has not been determined,” he noted.

Reports in the community

Yamauchi discussed the case of a 2-year-old child who was sent home after surgery with no complications. He returned to his physician with an MRSA infection. This child had a dog in the home. The dog was cultured and it had the same MRSA as the child. Yamauchi noted that this could be a coincidence and that it is unknown whether the child contracted MRSA from the dog or vice versa.

In a second case, a mother, her child and her dog were all positive for MRSA.

Because of the risk of transmission of disease from animal to human, questions about animal contact or animals in the home should be included as part of the patient’s history. Additionally, if a patient tests positive for one of the above conditions, animal contact should be determined. – Michelle Stephenson