2. • organism, usually single-celled and heterotrophic (using organic carbon as a source
of energy)
• All protozoans are eukaryotes and therefore possess a “true,” or membrane-bound,
nucleus.
• They also are nonfilamentous (in contrast to organisms such as molds, a group of
fungi, which have filaments called hyphae) and are confined to moist or aquatic
habitats.
• many protists are mixotrophs i.e capable of both heterotrophy (secondary energy
derivation through the consumption of other organisms) and autotrophy (primary
energy derivation, such as through the capture of sunlight or metabolism of
chemicals in the environment).
• Protozoans are motile
• Protozoans are also strictly non-multicellular and exist as either solitary cells or cell
colonies.
3. Cryptosporidium is a protozoan enteric parasite of humans and other vertebrates
The species C. parvum is of medical and economic relevance as it affects both
humans and cattle with its primary site of infection being the gastrointestinal tract
It affects the epithelial lining of the ileum, resulting in self-limiting diarrhoea
Belonging to the phylum of apicomplexan parasites
Cryptosporidium parvum is although not normally associated with foodborne out-
breaks of disease but pose potential problems for food and drink manufacturers.
Food or water are vehicle of transmission, and this pathogen is of greater
concern to manufacturers in developed countries as a consequence of the increase in
globalisation of food supplies.
CRYPTOSPORIDIUM
4. HABITAT
• Small intestine
• Appendix
• Colon
• Rectum
• Pulmonary tree
Source of infection
• Putting something in your mouth or accidentally swallowing something that
has come in contact with the stool of a person or animal infected with Crypto.
• Swallowing recreational water contaminated with Crypto. Recreational water
can be contaminated with sewage or feces from humans or animals.
• Swallowing water or beverages contaminated by stool from infected humans or
animals.
5. • Eating uncooked food contaminated with Crypto. All fruits and vegetables you plan
to eat raw should be thoroughly washed with uncontaminated water.
• Touching your mouth with contaminated hands. Hands can become contaminated
through a variety of activities, such as:
– touching surfaces (e.g., toys, bathroom fixtures, changing tables, diaper pails)
that have been contaminated by stool from an infected person,
– changing diapers,
– caring for an infected person, and
– handling an infected animal such as a cow or calf.
People with greater exposure to contaminated materials are more at risk for infection
such as:
• Children who attend childcare centers, including diaper-aged children
• Childcare workers
• Parents of infected children
• Older adults (ages 75 years and older)
• People who take care of other people with cryptosporidiosis
6. • International travelers
• Backpackers, hikers, and campers who drink
unfiltered, untreated water
• People who drink from untreated shallow,
unprotected wells
• People, including swimmers, who swallow
water from contaminated sources
• People who handle infected cattle
7. LIFE CYCLE
Oocysts of C. parvum can be ingested in food or drink, or transferred from hand to mouth.
Enters into GT tract of human and releases infective sprozoites
Attatch to the apical membrane of host epithelial cells and release mature merozoites
The merozoites infect other epithelial cells and mature into gametocytes
Releases oocytes which are excreted in faeces into enviromnent to start a new life cycle
8. Morphology of oocytes
Oocytes are sperical, oval and 5µm in size
Dose not stain with iodine and in acid fast staining
Resistant upto 60°c
Sequential application of ozone and chlorine eliminates cyst
Two types of oocyst are produced
Thinwalled oocysts that cause further (auto-) infection of the host and
Thick-walled oocysts that can survive in the environment after being shed in the
faeces.
The faeces of infected animal and human contain large numbers of oocysts
C. parvum oocysts are widespread in the environment and are often found in
surface waters.
9. Oocysts survive well in cool, damp conditions
Because of its chlorine resistance C. parvum has been a particular threat to
drinking water supplies
10.
11. Occurrence of Cryptosporidium in the agricultural environment
Oocysts may be present in faeces of infected wild and domestic animals.
Infected calves and lambs can excrete up to 1010 oocysts daily for 14 d. Infected
calves may shed 107 oocysts per gram of faeces.
The high output of oocysts together with the broad host range ensures a high
level of contamination in the environment and favours waterborne transmission of
the disease.
Oocysts may remain viable for months in moist soil or clean water although they
are prone to dessication.
The faecal material prevents oocysts from dessicating and viable oocysts are
therefore found in effluent discharges, agricultural runoff and muck in a watershed,
thus facilitating waterborne transmission of cryptosporidiosi
12. Sources of Human Infection and Routes of Transmission
The source of Cryptosporidium may be either animal or human faecal
material containing oocysts.
The relative importance of the primary source of oocysts, i.e. from
livestock, wildlife and sewage of septic systems is largely undetermined.
Studies have indicated that oocysts isolated from humans generally
exhibit characteristics specific to human strains rather than animal strains
Direct contact with faeces from an infected person or animal can result in
transmission of Cryptosporidium, but some cases involve indirect
transmission via faecal contamination of environmental surfaces, foodstuffs
or potable water supplies.
13. Water Treatment Processes
chlorine dioxide appears to be more effective the doses required were inappropriate
for water treatment.
Ozone appears to be the most effective disinfectant tested to date although the doses
required for treatment of cold water are beyond the levels normally applied for other
treatment purposes
Effective flocculation and filtration during conventional water treatment may remove
oocysts, but at present potable water that is constantly free of oocysts cannot be
guaranteed.
In the future, active oxygen species may be more usefully exploited for the
elimination of Cryptosporidium using techniques incorporating the use of ultrasound,
ultraviolet light and ozone
14. Heat treatment
Work by Fayer on the effect of high temperatures on the infectivity of oocysts
concluded that when water containing oocysts was heated to > 72.4 °C or higher
within 1 min, or when the temperature was held at > 64.2 °C for 2 min of a 5 min
heating cycle, infectivity was lost, indicating that C. parvum oocysts in water can
be rendered noninfectious when held for a relatively short time at these
temperatures.
15. Identification and Enumeration of Oocysts in Water and Foods
Methodology
For water supplies, current routine methodology involves the use of concentration
followed by immunofluorescence microscopy
i) sample collection
ii) elution, clarification and concentration
iii) microscopic identification using fluorescent labelled monoclonal
antibodies followed by confirmation using Nomarski optics
For any object to be regarded as an oocyst using the fluorescein isothiocyanate–
monoclonal antibody conjugate, certain criteria must be met regarding fluorescence,
size and shape.(Oocysts are almost spherical in shape and 4–6 µm diameter)
16. Cyclospora
Cyclospora is an apicomplexan, cyst-forming coccidian protozoan that belongs to
subphylum Apicomplexa, subclass Coccidiasina, and family Eimeriidae
Currently, nineteen Cyclospora species have been reported to be causative agents of
disease in various animal species and only one species, C. cayetanensis, is known to be
associated with syndromes of acute and chronic diarrhea in humans.
It is endemic in tropical and subtropical areas, but it has been identified as the
causative agent of several outbreaks worldwide in the last two decades and it is also
considered as a significant contributor to global gastroenteritis spread .
17. INFECTION
Cyclospora is a fecal-oral pathogen with spherical oocysts that measure 8 to 10 µm
in diameter
Its oocysts are unsporulated when excreted and require a few days or weeks to
become sporulated and infectious, depending upon the environmental conditions
Human infection occurs via produce consumption or contact with fecally
contaminated water, sewage, and soil
18.
19. STRUCTURE
Oocysts are typically between 8 and 10 mm in diameter and are spherical in shape
with an outer fibrillar (63 nm) coat that covers a thick cell wall (50 nm). As a
comparison, Cryptosporidium parvum oocysts are approximately half the size (45.5
mm) and slightly ovoid in shape. Each C. cayetanensis oocyst holds two sporocysts
and each sporocyst contains two sporozoites
21. DETECTION
• The methodology for the detection of any protozoan from any substrate can be
divided into four basic steps
1. Collection and concentration
2. purification
3. detection
4. viability
23. VIABILITY
40 ,6-diamidino-2-phenylindole and through reverse transcriptase (RT)-PCR .
Cyclospora cayetanensis oocysts can be induced to sporulate in vitro; typically
between 8 and 14 days after shedding in either distilled water or potassium
dichromate at temperatures ranging from 22 to 30°C . Those oocysts that have
sporulated are then treated with bile salts, sodium taurocholate and subjected to
mechanical pressure using a glass tube mortar and pestle to release sporocysts and
the subsequent freeing sporozoites through excystation .
A recently described means of determining viability is electro-rotation. This
technique detects changes in the physiochemical properties and morphology of an
oocyst. The oocyst is subjected to a uniform rotating electric field generated by four
gold-plated electrodes (voltages in the range of 100 Hz–10 mHz). The oocyst
rotates dependent upon its conductivity and permittivity. The oocyst’s rotation is
observed under phase-contrast (400 × ) and a video recording is made of its
movement. Rotation characteristics of the oocyst are used to determine whether or
not it is viable
24. CONTROL
• Improving general sanitary conditions is likely to help to reduce exposure to feces,
and contamination of water and food.
25. NEMATODES
Anisakis allergy
Anisakids are parasitic nematodes belonging to the Phylum Nemathelmintes, Class
Nematoda, Ascarida order, suborder Ascaridina, Anisakidae family .
Anisakiasis is the zoonotic disease triggered by the third stage larvae of nematodes,
Anisakis
This parasite habitually parasitises adult marine mammals. Intermediate and/or
paratenic hosts of the larvae are crustaceans, cephalopods and Humans are
accidentally infected when hosts are ingested either as raw or inadequately cooked
or treated fish/shellfish meals.
The L3 larvae of the genus Anisakis have been found in several economically
important fish species.
27. ANISAKIS BIOLOGY
The L3 stage larvae displays a coiled shape, which when uncoiled, is about 2 cm
long
Two main mechanisms are reported to be responsible for anisakiasis: allergic
reactions and direct tissue damage as a result of the penetration of the infective
larvae into the target organ site
29. PREVENTION OF ANISAKIASIS
Anisakids are known to survive and be resistant to different treatment conditions such
as freezing, microwaving, heating, salting, as well as use of drugs and condiments
Storage, after-harvest handling and fish preparation are the focus of preventive
measures.
Migration of larvae into the muscle might be prevented by immediate evisceration
of fish after being caught
. The US Food and Drug Administration (FDA) recommended that fish be cooked
to a temperature of at least 63 °C–74 °C before consumption
The FDA has recommended that fish be kept frozen at −20 °C for at least 168 h or
blast-frozen at −35 °C for at least 15 h
