EH203 INFECTIOUS & LIFESTYLE DISEASES

PLAGUE

By: Joshua Seli

CONTENT

Introduction/summary Identify the types of plague Signs and Symptoms Diagnosis Transmission Incubation period & Period of

communicability Occurrence and distribution Control and prevention Treatment Surveillance

WHAT IS PLAGUE?/SUMMURY Plague is a deadly epidemic or

pestilence infectious disease and potentially lethal, causing high mortality and serious historic events.

The causative organism is a bacterium called Yersinia Pestis.

Generally rats are the carrying agents of the fleas. These fleas carry the bacteria with them. Once bitten by the infected flea, the infection gets transmitted.

But rat and fleas are not only the major transmitting agent, the bacteria survives in many other species and quickly spreads. And it’s known to cause major pandemics

Today plague is uncommon, due to better living conditions and antibiotics.

BRIEF HISTORY

The plague has been considered as a cause of the few really major historic pandemics or the epidemic spread over large and multiple regions worldwide.

Plague killed millions in the 14th century and was called the Black Death and in 1900, there was an outbreak of plague in San Francisco caused by infected rats brought by a ship.

In the mid-1800s, it killed 12 million people in China. Today, thanks to better living conditions, antibiotics, and improved sanitation, current World Health Organization statistics show there were only 2,118 cases in 2003 worldwide.

TYPES OF PLAGUE

Here are the three form of plague

EPIDEOLOGY Papua New Guinea doesn’t

experience this but in other parts of the world they do, in particularly in the United State witness’s approximately 18 cases every year. Outside the United States, there are average reported 1,666 cases from 1967-1993. And here are average few countries that have shown highest cases of plague, Tanzania, Zaire, Peru, Vietnam, Madagascar, Burma, Uganda, China, etc.

CAUSES

Rodents such as rats carry a flea Known as Oriental rat flea which as the infectious bacterium Yersinia pestis. As the flea bites the humans or animals the bacteria is transmitted.

SIGNS & SYMPTOMS Plague symptoms depend on how

the patient was exposed to the plague bacteria. Plague can take different clinical forms, but the most common are bubonic, pneumonic and septicemic. Following are the various signs and symptoms noted in the various types of plagues:

Enlarged lymph nodes. Sore throat, Cough (may contain

blood), Shortness of breath. Body aches, General feeling of

illness, Blackish skin tissue Headache, Fever, Weakness, Stiff

neck ,Confusion, seizures Nausea, vomiting, abdominal pain,

Constipation, diarrhea, and black or tarry stools

DIAGNOSIS Plague is a plausible diagnosis for people who

are sick and live in, or have recently traveled to plague-endemic area.

Diagnosis is made by taking samples from the patient, especially blood or part of a swollen lymph gland, and submitting them for laboratory testing. Once plague has been identified as a possible cause of the illness, appropriate treatment should begin immediately. Below are some ways to test;

Blood culture and Sputum culture: These are advised to look for the presence of the bacterium Yersinia pestis.

Serologic tests: These aid to arrive at the diagnosis. Serum tested for fraction 1 envelope antigen and antibody. A single positive test in a patient who neither had plague before nor received plague vaccine is suggestive of an infection.

X-ray Chest: An x-ray of the chest tells about the lung infection and its severity

TRANSMISSION The plague bacteria can

be transmitted to human in many ways, through;

A flea bite Contact with

contaminated fluid Infectious droplets, like

for example if someone is infected and when sneezing or coughing the uninfected person breathing air contaminated with the bacteria is likely to get pneumonic plague.

PREVENTION & RICKS FACTORS Rat control and watching for the

disease in the wild rodent population are the main measures used to control the risk of epidemics.

A vaccination is available for high-risk workers, but its effectiveness is not clearly established.

There are many ways to prevent this disease and here below are some preventative measures to avoid plague. Avoid;

Contact with the infected animals or rodents.

Living in endemic area i.e. place where plague is common.

Exposure to flea bites, Working in the farm and Travel through rural areas

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. Today we have variety antibiotics which are effective against the disease. These include doxycycline, gentamicin and aminoglycosides streptomycin. If the disease is identified soon after infection, the Plague is almost always treatable and patients make full recoveries

INCUBATION PERIOD & PERIOD OF COMMUNICABILITY Signs & Symptoms starts

2 – 6 days after exposure to bubonic plague.

2 – 4 days after exposure to pneumonic plague (since severe and occur very rapidly).

Not really clear for Septicemic plague because the disease normally present in blood stream where it proceed into lungs. But generally 2-6 days.

An unblocked infected flea can remain alive for several months that able to transmit infection.

Blocked infected fleas contained bacteria that multiply inside, sticking together and form a plug that blocks its stomach and cause it to starve.

In the process of feeding by force, it vomits infected blood back into the bite wound; infect the area and die, that infection is not transmitted to new host.

Pneumonic plague can be spread rapidly (they are highly infectious) within a large number of people although infected individuals will remain alive for only a few days.

SURVEILLANCE Regular trapping of rodents should be maintained to

check for infection and their flea populations. Notification of any confirmed or suspect case of plague must be made known to WHO and any person travelling from an area where there have been cases of plague must be placed under surveillance for 6 days.

SUMMARY Plague is an infectious disease caused by the Yersinia

pestis bacteria, which is primarily found in rodents the fleas that feed off of them.

The bacteria are passed to humans through flea or rodent bites.

There are three forms of plague: bubonic, septicemic, and pneumonic.

The symptoms and method of transmission vary with each form of plague.

Plague can be treated with antibiotics.

REFERRENCES

Dennis DT, Mead PS, Yersinia species, including plague. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009: chap 229.

http://health.utah.gov/epi/factsheets/plague.pdf

Webber, R. (1919 – 1993), Communicable Epidemiology and Control (2nd ed.). UK: London School of Hygiene and Tropical Medicine

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