Question

Now that you have completed you investigation of the Plague, you want to inform the public of the risk, vector, how to prevent the spread and how to protect families in your area. You need to design a means of disseminating the information you believe is most pertinent and responsible. Remember the year and what media of dissemination are available to you.

Answer 1

ANSWER

This information could be disseminated to the public in the form of an information Booklet

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PLAGUE

Introduction:

Plague is infamous for killing millions of people in Europe during the Middle Ages. Causative bacteria are found mainly in rodents, particularly rats, and in the fleas that feed on them. Today, modern antibiotics are effective in treating plague. Without prompt treatment, the disease can cause serious illness or death. Presently, human plague infections continue to occur in rural areas in the western United States, but significantly more cases occur in parts of Africa and Asia.

Meaning

• Plague is a disease that affects humans and other mammals. It is caused by the bacterium, Yersinia pestis.
• Humans usually get plague after being bitten by a rodent flea that is carrying the plague bacterium or by handling an animal infected with plague.

Vector

In rural plague foci, the black rat, Rattus rattus is admitted as the main reservoir of plague, and associated flea species are known as the plague vectors . Xenopsylla cheopis, the rat flea is accepted as the main vector, mainly found inside the human habitations.

How Plague is caused?

• Plague is an infectious disease caused by bacteria called Yersinia pestis.
• These bacteria are found mainly in rodents, particularly rats, and in the fleas that feed on them. Other animals and humans usually contract the bacteria from rodent or flea bites.
• About 1 in 7 of those infected die from the disease.

Ecology and Transmission

• The bacteria that cause plague, Yersinia pestis, maintain their existence in a cycle involving rodents and their fleas.
• Plague occurs in rural and semi-rural areas of the western United States, primarily in semi-arid upland forests and grasslands where many types of rodent species can be involved.
• Many types of animals, such as rock squirrels, wood rats, ground squirrels, prairie dogs, chipmunks, mice, voles, and rabbits can be affected by plague.
• Wild carnivores can become infected by eating other infected animals.
• These infected animals and their fleas serve as long-term reservoirs for the bacteria. This is called the enzootic cycle.
• Occasionally, other species become infected, causing an outbreak among animals, called an epizootic.
• Humans are usually more at risk during, or shortly after, a plague epizootic.
• Epizootics are most likely in areas with multiple types of rodents living in high densities and in diverse habitats.

Mode of Transmission

The plague bacteria can be transmitted to humans in the following ways:

Flea bites. Plague bacteria are most often transmitted by the bite of an infected flea.

• · . People and animals that visit places where rodents have recently died from plague are at risk of being infected from flea bites.
• · Dogs and cats may also bring plague-infected fleas into the home.
• Flea bite exposure may result in primary bubonic or septicemic plague.

Contact with contaminated fluid or tissue.

• · Humans can become infected when handling tissue or body fluids of a plague-infected animal.
• · For example, a hunter skinning a rabbit or other infected animal without using proper precautions could become infected with plague bacteria.
• · This form of exposure most commonly results in bubonic plague.

Infectious droplets.

• When a person has plague pneumonia, they may cough droplets containing the plague bacteria into air.
• If these bacteria-containing droplets are breathed in by another person they can cause pneumonic plague.
• Typically this requires direct and close contact with the person with pneumonic plague.

Symptoms

Plague can take different clinical forms, but the most common are bubonic, pneumonic, and septicemic.

Forms of plague.

Bubonic plague:

• · Patients develop sudden onset of fever, headache, chills, and weakness and one or more swollen, tender and painful lymph nodes (called buboes).
• · This form usually results from the bite of an infected flea.
• · The bacteria multiply in the lymph node closest to where the bacteria entered the human body and the bacteria can spread to other parts of the body.

Septicemic plague:

• · Patients develop fever, chills, extreme weakness, abdominal pain, shock, and possibly bleeding into the skin and other organs.
• · Skin and other tissues may turn black and die, especially on fingers, toes, and the nose.
• · Septicemic plague can occur as the first symptom of plague, or may develop from untreated bubonic plague.
• · This form results from bites of infected fleas or from handling an infected animal.

Pneumonic plague:

• · Patients develop fever, headache, weakness, and a rapidly developing pneumonia with shortness of breath, chest pain, cough, and sometimes bloody or watery mucous.
• · Develop from inhaling infectious droplets or may develop from untreated bubonic or septicemic plague after the bacteria spread to the lungs.
• · The pneumonia may cause respiratory failure and shock.
• · Pneumonic plague is the most serious form of the disease and is the only form of plague that can be spread from person to person (by infectious droplets).

Diagnosis

Diagnosis is made by

• Taking samples from the patient, especially
• · Lymph node aspirate
• · Blood cultures
• · Sputum
• Bronchial/tracheal washing may be taken from suspected pneumonic plague patients;

· In cases where live organisms are unculturable (such as postmortem), lymphoid, spleen, lung, and liver tissue or bone marrow samples may yield evidence of plague infection by direct detection methods such as direct fluorescent antibody (DFA) or PCR.

Treatment

• · Plague is a very serious illness, but is treatable with commonly available antibiotics.
• · The earlier a patient seeks medical care and receives treatment that is appropriate for plague, the better their chances are of a full recovery.
• · People in close contact with very sick pneumonic plague patients may be placed under observation.
• · Preventive antibiotic therapy may also be given, depending on the type and timing of personal contact.

Avoiding occupational risks

• Veterinary staff is at risk of plague if there is contact with infectious exudates, respiratory droplets, oral secretions, tissues or fleas.
• Any material used in examination of plague-suspect cats should be disinfected, autoclaved, or incinerated.
• Masks and gloves should be worn when examining and treating cats suspected of having plague.
• Veterinarians should use appropriate personal protective equipment (PPE) before beginning a necropsy on a plague-suspect animal. PPE should include gloves, an N95 respirator or the equivalent, and protective eye equipment.
• If any veterinary staff is exposed to infectious material, they should watch their health closely for 2 weeks following the exposure and discuss post-exposure prophylaxis or fever watch with a health care provider and public health officials.

Prevention and control

It is important that public health officials be notified promptly when plague is suspected in a cat.

• Public health officials will assist with follow-up investigations and implementation of preventive measures at sites where cats might have been exposed to minimize future risk.
• Follow-up will help identify persons who might have been exposed to the infected animal so that appropriate preventive measures, including prophylactic antibiotic therapy if indicated, can be implemented.
• Owners of plague–positive animals frequently ask veterinarians about their own risk of contracting plague. They should be advised:
  • That their risk of plague depends on the type of contact with the infected animal (casual contact versus inhalation of infectious coughed material).
  • To see their health care provider and watch their health closely for 2 weeks following the last possible contact with the infected animal.
  • That post-exposure antibiotic therapy may be warranted, depending on the type and duration of the contact. Health department personnel should be placed in touch with owners of plague-positive animals to ensure no animal–to–human transmission occurs.

General plague prevention messages can be disseminated by veterinarians to animal owners. These include:

• All ill animals, especially cats, should be seen by a veterinarian.
• Treat pet dogs and cats for flea control regularly and do not allow these animals to roam freely.
• Eliminate sources of food and nesting places for rodents around homes, work places, and recreation areas; remove brush, rock piles, junk, cluttered firewood, and potential food supplies, such as pet and wild animal food. Make your home rodent-proof.
• Pet owners should be encouraged to not pick up or touch dead animals.

General measures of Prevention

1. Reduce rodent habitat around your home, work place, and recreational areas. Remove brush, rock piles, junk, cluttered firewood, and possible rodent food supplies, such as pet and wild animal food. Make your home and outbuildings rodent-proof.
2. Wear gloves if you are handling or skinning potentially infected animals to prevent contact between your skin and the plague bacteria. Contact your local health department if you have questions about disposal of dead animals.
3. Use repellent if you think you could be exposed to rodent fleas during activities such as camping, hiking, or working outdoors. Products containing DEET can be applied to the skin as well as clothing and products containing permethrin can be applied to clothing (always follow instructions on the label).
4. Keep fleas off of your pets by applying flea control products. Animals that roam freely are more likely to come in contact with plague infected animals or fleas and could bring them into homes. If your pet becomes sick, seek care from a veterinarian as soon as possible.
5. Do not allow dogs or cats that roam free in endemic areas to sleep on your bed.

Managing plague outbreaks

• Find and stop the source of infection.
• Ø Identify the most likely source of infection in the area where the human case(s) was exposed.
• Ø Institute appropriate infection, prevention and control procedures.
• Ø Institute vector control, then rodent control. Killing rodents before vectors will cause the fleas to jump to new hosts, this is to be avoided.
• Protect health workers.
• Ø Inform and train them on infection prevention and control.
• Ø Workers in direct contact with pneumonic plague patients must wear standard precautions and receive a chemoprophylaxis with antibiotics for the duration of seven days or at least as long as they are exposed to infected patients.
• Ensure correct treatment: Verify that patients are being given appropriate antibiotic treatment and that local supplies of antibiotics are adequate.
• Isolate patients with pneumonic plague. Patients should be isolated so as not to infect others via air droplets. Providing masks for pneumonic patients can reduce spread.
• Surveillance:
• Ø Identify and monitor close contacts of pneumonic plague patients and give them a seven-day chemoprophylaxis.
• Ø Chemoprophylaxis should also be given to household members of bubonic plague patients.
• Obtain specimens

Which should be carefully collected using appropriate infection, prevention and control procedures and sent to labs for testing.

• Disinfection.

Routine hand-washing is recommended with soap and water or use of alcohol hand rub. Larger areas can be disinfected using 10% of diluted household bleach (made fresh daily).

• Ensure safe burial practices.
• Ø Spraying of face/chest area of suspected pneumonic plague deaths should be discouraged. The area should be covered with a disinfectant-soaked cloth or absorbent material.

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