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Cryptosporidium: Evading the Nemesis
Airplanes, Cruise ships. College dorms, recreational
pools. People, public places, and the organisms that inhabit them sometimes cry
mutiny against a healthy system wreaking havoc and ultimately causing distress.
Cryptosporidiom muris, or ‘Crypto’ in
short, is a single celled parasite most commonly known for causing Cryptosporidiosis,
a diarrheal disease.
The
causal agent of Cryptosporidiosis is a protozoan, a parasitic oocyst. Route of
infection most commonly includes contaminated drinking water (such as in
third-world countries with poor water supplies), extensive and unprotected
contact with livestock, especially bovines, and the occasional inhalation of an
oocyte through the respiratory route. Once ingested, the oocyst becomes a
sporozoite (spore releasing) and cycles between asexual (trophozooite or type I
meronts) or sexual (merozooite or type II) reproduction in the gastrointestinal
tract. In this tract, the parasite reproduces asexually (schizogony). Sexual
reproduction for the parasite differs from asexual in that gametogony produces
micro and macrogamonts (male and female, respectively). The results of this cycle are two different
oocysts, thick and thin-walled. The former is often excreted while the latter
preoccupies itself with further infectious duties. Because excretion is the end
of a cycle, the oocysts allows for infection directly after excretion
(Parasites).
Risk
factors and sources of infection are important measures in infection
prevention. Common sources of the parasite include food, water, or fomites
(door knobs, tables, tools etc.) which have been contaminated by feces from
infected sources. Risks range from direct contact (caring for an infected
individual, contact with infected animals, changing diapers) to swimming in community
pools, attending playgrounds, travelling, and many others. Public pools are
especially dangerous if children are defecating or voiding within the pool, and
recent outbreaks have been traced to this cause (Rettner). Sources of infection
include but are in no way limited to handling livestock without proper
protective measures (donning of gloves and boots, hand hygiene), campers or travelers
drinking questionable water, working with children, and even self- infection
(fecal oral route) if an individual is not taking care to wash their hands
frequently (Parasites).
Though
symptom intensity does vary between individuals (especially those with
immunosuppression and HIV/AIDS), the common symptoms are watery stool followed
by dehydration, nausea, vomiting, fever, and weight loss. Most often, the small
intestine is affected by the parasite, but the respiratory tract can be
subjected to infection if an oocyst is inhaled. Symptoms typically last a
fortnight (Parasites). Crypto can be cured by auto-recovery, that is, most
healthy immune systems will regain composure after infection; it is simply a
case of letting the parasite run its course, per se. A supporting measure is to
constantly drink fluids to replace water loss. For pregnant women, the fluid
loss can be extremely detrimental, while for babies it can prove to be fatal.
Additionally, those with HIV/AIDS should take even more measures to care for
their health because most Crypto symptoms will not be visible because of the
already compromised immune system.
It
was the beginning of the 2015 spring semester for veterinary medicine students
in Philadelphia, Pennsylvania when the school’s health center was alerted to
five cases of students with some type of gastrointestinal issue. Twenty-two
students had been present at a bovine obstetrics training session, and five of
these same twenty-two reported symptoms of cramps, nausea, vomiting, fever, and
diarrhea (the nausea and vomiting, like intermittent symptoms of malaria are
caused by release of merozooites after oocyte reproduction) CITE . After
further interviews and research, a total of sixteen students (including the
original five) had reported the said symptoms. With this factor in the
equation, specimens from the calves the students worked with were collected and
tested, and results of an acid-fast stain performed with a calf intestine smear
tested positive for oocysts of Cryptosporidium. Though the protocol for PPE (personal protective
equipment) was in place and all twenty-two students wore gloves, it is not
known how many of the students were vigilant about their outerwear and hand
hygiene.
Concerning the
student demographic, thirteen of the twenty-two were female, sixteen
symptomatic cases were reported. Of the sixteen reported cases, four
symptomatic students submitted specimen samples for case confirmation.
Interestingly, most cases were able to be classified as strict Crypto, just
because of the basis of definitions provided by the Centers for Disease Control
and Prevention. These cases were very obvious. Other testing used was direct
fluorescent antibody testing in which a dye stains the antigen making it
visible using microscopy. This testing determined the obstetrics lab as the
source of the outbreak.
This
outbreak was undoubtedly dangerous, and it could have been avoided providing
the students had followed the PPE protocol. Unfortunately, many people think
that washing hands after using the bathroom or touching animals is enough;
there is a reason why gloves and even coveralls paired with boots were called
for in this obstetrics laboratory. I think it important that students in any
science field follow protective measures implicitly. This does not mean no one
should ever play in public pools, have a garden, or raise calves - my family
does all of these and they are very rewarding. It does, however, mean increased
attentiveness to hygiene. I have had family members go through this horrible
infectious experience and it is something that could have been avoided; because
of this, I advocate attentive precautions.
Most often, ‘Crypto’
appears paired with a decreased vigilance in proper hygiene and or improper
handling of either specimens or animals. The oocyst or the Cryptosporidium
parasite “survives various environmental pressures, as low as -7.6 [degrees]F
(-22[degrees]C) for >700 hours”(Drinkard). This is fascinating, the way
these parasites seem to conquer their environment in order to survive. The
survival of these parasites in such variant temperatures, however, should be a
signal to those dealing with animals, whether in livestock or in veterinary
science, that proper protection is never not effective, Just because we do not
see a parasite does not indicate that it is not there. Such gastrointestinal
distress can be avoided if the correct protective and preventative measures are
applied.
Bibliography:
Drinkard, L., et al.
Outbreak of cryptosporidiosis among veterinary students – Philadeplphia,
Pennsylvania. Morbidity and Mortality Weekly Report,
64(28). 773.
Parasites,
Cryptosporidium: Diagnosis, risk factors, illness, symptoms, and treatment. Centers
for Disease Control and Prevention. (2015, April 2).
Retrieved Sept. 21, 2015.
Rettner, R. (2015).
Crypto parasite outbreaks increasing pools across the US. LiveScience.
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