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Notes Unit 19
Soilborne Diseases
Important Diseases
1. Anthrax
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
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Bacillus anthracis
Bacteria; Gram positive bacillus with endospore
Has endospores, which allow it to live for long periods of time.
The symptoms (warning signs) of anthrax are different depending on the type of
the disease. There are three types:
Cutaneous: The first symptom is a small sore that develops into a blister. The blister then
develops into a skin ulcer with a black area in the center. The sore, blister and ulcer do not hurt.
Gastrointestinal: The first symptoms are nausea, loss of appetite, bloody diarrhea, and fever,
followed by bad stomach pain.
Inhalation: The first symptoms of inhalation anthrax are like cold or flu symptoms and can
include a sore throat, mild fever and muscle aches. Later symptoms include cough, chest
discomfort, shortness of breath, tiredness and muscle aches.
Hallmark:
Varies depending on type.
Transmission:
From Animals: Humans can become infected with anthrax by handling products
from infected animals or by breathing in anthrax spores from infected animal
products (like wool, for example). People can also become infected with
gastrointestinal anthrax by eating undercooked meat from infected animals.
As A Weapon: Anthrax also can be used as a weapon. This happened in the
United States in 2001. Anthrax was deliberately spread through the postal system
by sending letters with powder containing anthrax. This caused 22 cases of
anthrax infection.
Antibiotics and a vaccine available.
Treatment:
2. Tetanus
Causative Organism:
Type of Organism:
Pathogenicity:
Hallmark:
Transmission:
Treatment:
Clostridium tetani
Bacteria: Gram positive bacillus with an endospore
Produces a neurotoxin, tetanospasmin, that is released upon death of the bacteria.
It enters the CNS through peripheral nerves and blood. Causes muscle spasms.
Symptoms: Early symptoms: lockjaw, stiffness in the neck and abdomen, and
difficulty swallowing. Later symptoms: severe muscle spasms, generalized
seizure-like activity, severe nervous system disorders.
Obtained through dirty puncture wound. Also called “Lockjaw.”
Contaminated soil, especially in soils contaminated with animal feces. Enters the
body through a break in the skin
Tetanus antitoxin; best to prevent with vaccination
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3. Leptospirosis (Swamp Fever)
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Transmission:
Treatment:
Leptospira interrogans
Bacteria, spirochete
Frequently confused with other diseases
Wide range of symptoms, and some infected persons may have no symptoms at
all. Symptoms include high fever, severe headache, chills, muscle aches, and
vomiting, and may include jaundice (yellow skin and eyes), red eyes, abdominal
pain, diarrhea, or a rash. If the disease is not treated, the patient could develop
kidney damage, meningitis (inflammation of the membrane around the brain and
spinal cord), liver failure, and respiratory distress. In rare cases death occurs.
Usually caused by exposure to water contaminated with the urine of infected
animals. Many different kinds of animals carry the bacterium; they may become
sick but sometimes have no symptoms. Leptospira organisms have been found in
cattle, pigs, horses, dogs, rodents, and wild animals. Humans become infected
through contact with water, food, or soil containing urine from these infected
animals. This may happen by swallowing contaminated food or water or through
skin contact, especially with mucosal surfaces, such as the eyes or nose, or with
broken skin. The disease is not known to be spread from person to person.
Antibiotics
4. Psittacosis
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Hallmark:
Transmission:
Treatment:
Chlamydia psittaci
Bacteria; Gram negative, intracellular bacteria
Tiny, elementary bodies are part of life cycle which are resistant to environmental
stress
Form of pneumonia where you have fever, headache, muscle aches, chills, and a
dry cough. Heart, liver, and neurological damage may also occur.
Pneumonia from infected bird droppings.
Infection is acquired by inhaling dried secretions from infected birds. Although
all birds are susceptible, pet birds (parrots, parakeets, macaws, and cockatiels) and
poultry (turkeys and ducks) are most frequently involved in transmission to
humans.
Antibiotics.
5. Histoplasmosis
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Hallmark:
Transmission:
Histoplasma capsulatum
Fungus
Affects mainly people that live in states adjoining the Mississippi and Ohio Rivers
Most infected persons have no apparent ill effects. The acute respiratory disease is
characterized by respiratory symptoms, a general ill feeling, fever, chest pains,
and a dry or nonproductive cough. Distinct patterns may be seen on a chest x-ray.
Get from bats and birds, causes pneumonia-like symptoms.
Grows in soil and material contaminated with bat or bird droppings. Spores
become airborne when contaminated soil is disturbed. Breathing the spores causes
infection. The disease is not transmitted from an infected person to someone else.
The fungus has been found in poultry house litter, caves, areas harboring bats, and
in bird roosts.
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Treatment:
Antifungal medication
6. Coccidioidomycosis (San Joaquin Fever)
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Hallmark:
Transmission:
Treatment:
Coccidioides immitis
Fungus
Usually found in the dry, alkaline soils of South America and North Mexico.
Also found in the San Joaquin valley in California.
Symptomatic infection (40% of cases) usually presents as flu-like illness with
fever, cough, headaches, rash, and muscle aches. Some patients fail to recover and
develop chronic pulmonary infection or widespread disseminated infection
(affecting meninges, soft tissues, joints, and bone). Severe pulmonary disease may
develop in HIV-infected persons.
Flu-like illness from breathing in dirty air in Southwest
Inhalation of airborne spores after disturbance of contaminated soil by humans or
natural disasters (e.g., dust storms and earthquakes).
Antifungal medication
7. Ascariasis
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Hallmark:
Transmission:
Treatment:
Ascaris lumbricoides
parasitic helminth
Can block intestines; deplete nutrients
Most people have no symptoms that are noticeable, but infection may cause
slower growth and slower weight gain. If you are heavily infected, you may have
abdominal pain. Sometimes, while the immature worms migrate through the
lungs, you may cough and have difficulty breathing. If you have a very heavy
worm infection, your intestines may become blocked.
Worm infection in the gut.
You or your children can become infected after touching your mouth with your
hands that have become contaminated with eggs from soil or other contaminated
surfaces or by ingesting contaminated food. Ascaris eggs are found in human
feces. After feces contaminate the soil, the eggs become infectious after a few
weeks. Infection occurs when a person accidentally ingests (swallows) infectious
Ascaris eggs. Once in the small intestines, immature worms hatch from the eggs.
The larvae are carried through the lungs and then to the throat where they are
swallowed. Once swallowed, they reach the intestines and develop into adult
worms. Adult female worms lay eggs that are then passed in feces; this cycle will
take between 2-3 months. Worms can get to be 1 foot long or longer!
Anti-helminth medication.
8. Fungal Skin Infections
Causative Organism:
Type of Organism:
Pathogenicity:
Tinea sp.
Fungus
None.
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Diseases Caused:
Transmission:
Treatment:
Below are 4 of the most common diseases caused by fungi:
a. Tinea capitis – Ringworm of the scalp – can lead to bald patches.
b. Tinea cruris – “Jock Itch” – ringworm of the groin
c. Tinea pedis – “Athlete’s Foot” – ringworm of the feet
d. Tinea unguium – fungal finger and toe nail infection
Person to person contact, or contact with fomites. Fungus prefers moist
conditions. Fungus thrives in moist conditions and in soil.
Antifungal medications.
9. Hookworm
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Transmission:
Treatment:
Ancylostoma duodenale (found in Europe, Africa, Asia, South America)
Necator americanus (found is United States)
Helminth (worm)
Can cause anemia
An itchy, slightly raised rash called "ground itch" may appear around the area
where the larvae first bored through the skin. The skin in this area may become
red and swollen. This lasts for several days and commonly occurs between the
toes. The larvae are then pumped into the lungs. There, they bore into the tiny
airsacs (alveoli) of the lungs. Their presence within the lungs usually causes
enough irritation to produce coughing, fever, and wheezing. However, some
people have none of these symptoms. The larvae are coughed up into the throat
and mouth, and are then swallowed and passed into the small intestine. Within the
intestine they develop into the adult worm. Hookworms cause trouble for their
human host when they attach their mouths to the lining of the small intestine and
suck the person's blood. Once established within the intestine, the adult worms
can cause pain, decreased appetite, diarrhea, and weight loss. The worms suck
between 0.03-0.2 ml of blood per day. When a worm moves from one area of the
intestine to another, it detaches its mouth from the intestinal lining, leaving an
irritated area that may continue to bleed for some time. This results in even
further blood loss. A single adult worm can live for up to 14 years in a patient's
intestine. Over time, the patient's blood loss may be significant. Anemia is the
most serious complication of hookworm disease, progressing over months or
years. Children are particularly harmed by such anemia and can suffer from heart
problems, mental retardation, slowed growth, and delayed sexual development. In
infants, hookworm disease can be deadly.
Eggs are passed out of the host's body in feces. The eggs enter the soil, where
they incubate. After about 48 hours, the immature larval form hatches out of the
eggs. These larvae take about six weeks to develop into the mature larval form
that is capable of causing human infection. If exposed to human skin at this point
(usually bare feet walking in the dirt or bare hands digging in the dirt), the larvae
will bore through the skin and ride through the lymph circulation to the right side
of the heart.
Anti-helminth medication.
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10. Strongyloidiasis
Causative Organism:
Type of Organism:
Pathogenicity:
Symptoms:
Transmission:
Treatment:
Strongyloides stercoralis (threadworm)
Helminth (worm)
None
Frequently asymptomatic. Gastrointestinal symptoms include abdominal pain and
diarrhea. Pulmonary symptoms (including Loeffler’s syndrome) can occur during
pulmonary (lung) migration of the larvae. Skin problems include itchy rashes in
the buttocks and waist areas. In immunocompromised people, can move
throughout the whole body and can present with abdominal pain and swelling,
shock, pulmonary and neurologic complications and infection of blood, and is
potentially fatal.
From contaminated soil, penetrate human skin and migrate to lungs, and then are
coughed up and swallowed. Mostly in places with poor sanitation.
Anti-helminth medication.
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