Communicable Disease Surveillance

Influenza

Influenza is a highly contagious viral respiratory illness that affects the health of large numbers of people every year. Most people recover within a week, but a cough and tiredness can last two weeks or longer. Some of the complications caused by influenza include bacterial pneumonia, dehydration, and worsening of chronic medical conditions, such as congestive heart failure, asthma, or diabetes. Children may get sinus problems and ear infections as complications from the flu. Those aged 65 years and older, children under age 2, and persons of any age with chronic medical conditions are at highest risk for serious complications of flu. The most common complication is pneumonia. In the United States, influenza and pneumonia combined is among the top 10 leading causes of death. On average, influenza is annually associated with more than 36,000 deaths and more than 200,000 hospitalizations. In Missouri, influenza and pneumonia are associated with approximately 1,500 – 3,000 deaths per year. The economic impact of influenza illness is staggering. Studies have shown that in an average year, direct and indirect medical costs in the U.S. are in the billions.

Studies have indicated that influenza vaccine efficiency is approximately 70%-90% effective in preventing illness among persons 65 years of age or less. It is 30%-40% effective among the frail elderly, 50%-60% effective in preventing hospitalization, and approximately 80% effective in preventing death. The degree of effectiveness is dependent on a good match between the circulating influenza strains and the components included in the influenza vaccine each year. It also depends on the ability of each person’s immune system to effectively produce an antibody against the virus.

Don’t forget to get your flu shot this season

Rabies Rabies is a viral disease of mammals and is transmitted primarily through bites. Annually, 7,000 to 8,000 rabid animals are detected in the United States, with more than 90 percent of the cases in wild animals. Rabies is found naturally in Missouri, occurring primarily in bats and skunks, although other animals are also found rabid each year, including domestic species such as dogs, cats, horses, and cattle. The annual number of rabid animals reported in Missouri during the ten-year period 1995 through 2004 ranged from 26 to 59 (average of 40 cases per year). Although rabies is transmitted to humans almost entirely through bites from rabid animals, contamination of open wounds or mucous membranes with saliva or nervous tissue from a rabid animal could potentially constitute an exposure. Rabies in humans is almost invariably fatal. Fortunately, human deaths in the United States have become relatively rare because: (1) effective vaccinations have been available for dogs and cats since the 1950s, (2) public health practices such as animal quarantine and testing are aggressively pursued, and (3) improved anti-rabies shots have been developed for persons exposed to rabies. The last human rabies fatality in Missouri was reported in 1959, although many Missourians receive the anti-rabies series of shots each year. The Centers for Disease Control and Prevention (CDC) estimates that 40,000 persons in the United States receive the anti-rabies series of shots annually. Rabies in both animals and humans in Missouri is reportable to the Missouri Department of Health and Senior Services¹. Rabies in Animals The incubation period (time from exposure to signs of illness) of rabies in domestic animals such as dogs and cats can be quite variable, but averages three to six weeks. The first sign of rabies in animals is often a change in temperament or behavior. For example, a friendly dog may become reclusive (or vice versa) and nocturnal wild animals such as skunks may become active during the daytime. In the next stage, classically referred to as “furious” rabies, the animal will attack and bite other animals, objects, or people. The final stage is referred to as “dumb” rabies, and at this point the animal is partially or completely paralyzed and close to death. Often, there is paralysis of the throat muscles, resulting in an inability to swallow and profuse salivation. The animal may want to drink water, but painful throat muscle spasms prevent this. Excess salivation may result in “frothing at the mouth,” but this characteristic is often observed in animals dying from other causes as well. An animal may go through all of these stages or only some of them. Death is virtually certain within ten days of onset of signs. A dog, cat, or ferret may be infectious (have rabies virus in its saliva) for several days before it develops any outward signs of disease. Whether this is true, and for what time period, is unknown for other animal species. Vaccination of Animals Effective rabies vaccines are available for dogs, cats, ferrets, sheep, cattle, and horses. Vaccination of cats and dogs is crucial, since vaccinated pets are a protective barrier between the people who own and interact with them and rabid wild animals with which the pets might have contact. Dogs and cats whose owners consider them to be “indoor animals” should also be vaccinated because these pets often have exposures to other animals, either by the dog or cat being unintentionally released to the outdoors, or by wild animals such as bats getting into the house. Vaccinations must be administered by a licensed veterinarian. Primary and booster vaccinations should be obtained in accordance with recommendations from licensed veterinarians and in accordance with local animal control ordinances. There is no post-exposure treatment available for animals as there is for humans. Information pertaining to animal rabies vaccines as well as the prevention and control of rabies in animals is available in the Compendium of Animal Rabies Prevention and Control, 2005². Actions Following a Potential Rabies Exposure The following actions should be taken if a person is bitten or otherwise possibly exposed to a rabid animal: Domestic animals: Identify and, if possible, confine the biting animal. Dogs, cats, and ferrets may be quarantined for ten days (if healthy and depending on other circumstances), or they may be euthanized and tested for rabies. Other domestic animals are handled on a case-by-case basis. Wild animals: Identify and, if possible, confine the biting animal for rabies testing. No quarantine period is recognized for wild animals. Wash the wound immediately and thoroughly with soap and water for 10 to 15 minutes. Consult with a physician to: (1) check the tetanus immunization status, (2) determine if antibiotic treatment is needed for bacterial infection, (3) determine if other medical procedures are necessary, such as sutures in the case of disfiguring wounds, and (4) have a rabies risk assessment accomplished, including determining if the anti-rabies series of shots is warranted. Tips for Children Children suffer a disproportionate number of bites from animals, often resulting in serious injury to the face, head, and neck. The following tips can help children avoid being bitten, and the resulting physical/mental trauma and potential exposure to rabies and other diseases that accompany bites: Never touch unfamiliar or wild animals. Enjoy wild animals from afar. Avoid direct contact with stray animals. Stray cats and dogs may not have been vaccinated against rabies. Never adopt wild animals or bring them into the home. Do not try to nurse sick animals to health. It is common to want to rescue and nurse a hurt wild animal, but that animal may have rabies. Ask an adult to call an animal control officer or animal rescue group for help with the sick animal. Make sure that trash cans and pet foods are secured so that they do not attract wild animals. Do not disturb a dog that is sleeping, eating, or caring for puppies. If bitten, report the bite to an adult immediately.