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a)
The first approach is not really a disinfection technique, but can be a feasible method for ensuring the safety of uncooked meat and fish. It includes improvements in the sterility of food-processing equipment combined with polymerase chain reaction (PCR) screening for all expected pathogens (Table 7 below). The proposed screening procedure can be the following: food samples are lysed and the DNA isolated and analyzed by several multiplex PCR reactions using primers specific to genomic DNA of the expected pathogens (
Table 1
) [
540
,
541
]. To reduce the number of simultaneous tests in a multiplex PCR reaction, it may be possible to use universal primers for some groups of pathogens. For example, one pair of universal primers for bacteria [
542
] can replace twelve tests for bacterial pathogens listed in Table 7 below. The screening may also include testing for prions [
543
]. In order to obtain the most representative samples for testing, fine grinding and thorough mixing may be necessary prior to sampling [
541
]. In addition, a single freeze-thaw cycle can be incorporated into this approach because it can kill some multicellular and single-celled parasites [
563
-
565
] (but not others [
566
,
567
]). Doctors use a similar method for ensuring the safety of donor blood: they screen it thoroughly for all expected pathogens, instead of active sterilization by autoclaving or addition of antibiotics [
568
].
b)
Another possible disinfection method can be preparation of soluble extracts that can be sterilized by ultrafiltration. A water extract from finely ground animal products can be prepared using a method such as sonication followed by centrifugation. The extract can then be sterilized by passing it through a series of filters ending with a filter of 0.2-micron pore size. Most yeast cells will be removed by a 0.5-micron filter and virtually all bacteria will be removed by a 0.2-micron filter [
245
].
If any of these approaches (or other relevant ideas) are implemented and receive regulatory approval, the resulting food products may turn out to be expensive. The cost should come down with further technological improvements, provided that there is a demand in the marketplace.
Current treatment guidelines for relevant infectious diseases.
Currently available clinical evidence suggests that most of the infections that can result from consumption of uncooked animal products can be treated effectively by antibiotics or antiparasitic agents combined with supportive therapy, i.e. alleviation of symptoms of an infectious illness. For example, analgesics and antipyretics can reduce pain and fever, while rehydration can help to compensate for water loss with diarrhea. For some infections, the use of antibiotics is not effective. Some parasites, such as pork tapeworm, may cause damage to the central nervous system (neurocysticercosis) which can result in seizures or a fatal outcome. Infection with some pathogens may be asymptomatic or may result in a mild illness in healthy people, but can cause a serious illness in immunocompromised patients. Table 7 below summarizes treatments currently used in clinical practice. You can read about other interventions that may also be useful in food-borne infections in the section that follows the table.
Table 7.
Current treatment guidelines for common infectious diseases that may result from consumption of raw animal products [
544
]. Symptoms of infection and source foods are listed in
Table 1
.
----------------------------------
Infection
:
Angiostrongylus cantonensis
(parasitic worm)
Treatment
:
Albendazole, corticosteroids, supportive care.
References for PCR primers for food testing
:
[
545
]
Infection
:
Campylobacter jejuni
(bacterium)
Treatment
:
Supportive care; in severe cases, antibiotics erythromycin and quinolones may be indicated at the early stages of the diarrheal disease.
References for PCR primers for food testing
:
[
546
,
547
]
Infection
:
Clostridium botulinum
(bacterium)
Treatment
:
Supportive care; botulinum antitoxin is helpful if given early in the course of the illness; anti-botulism immunoglobulin instead of botulinum antitoxin is recommended for infants.
References for PCR primers for food testing
:
[
548
]
Infection
:
Clostridium perfringens
(bacterium)
Treatment
:
Supportive care; do not use antibiotics.
References for PCR primers for food testing
:
[
549
]
Infection
:
Cryptosporidium parvum
(single-celled parasite)
Treatment
:
Supportive care; in severe cases, paromomycin for 7 days may be considered. For children under 11, nitazoxanide for 3 days may be considered.
References for PCR primers for food testing
:
[
550
]
Infection
:
Escherichia coli
, strain O157:H7 (bacterium)
Treatment
:
Supportive care with close monitoring of renal function, hemoglobin, and platelets; antibiotics may be harmful.
E. coli
0157:H7 infection is associated with hemolytic uremic syndrome; studies suggest that antibiotics may promote the development of hemolytic uremic syndrome.
References for PCR primers for food testing
:
[
547
,
551
]
Infection
:
Giardia duodenalis
(single-celled parasite)
Treatment
:
Metronidazole
References for PCR primers for food testing
:
[
552
,
553
]
Infection
:
Listeria monocytogenes
(bacterium)
Treatment
:
Supportive care and antibiotics; intravenous ampicillin, penicillin, or trimethoprim/sulfamethoxazole are recommended if the disease is invasive (bacteremia or meningitis).
References for PCR primers for food testing
:
[
551
]
Infection
:
Norwalk virus
and
norovirus
(Norwalk-like virus)
Treatment
:
Supportive care, including rehydration; good hygiene.
References for PCR primers for food testing
:
[
554
,
555
]
Infection
:
Opisthorchis felineus
and
Opisthorchis viverrini
(flatworms)
Treatment
:
Praziquantel
References for PCR primers for food testing
:
[
556
,
557
]
Infection
:
Salmonella
(bacterium)
Treatment
:
Supportive care; except for
Salmonella typhi
, do not use antibiotics unless there is extra-intestinal spread of infection or the risk thereof. When applicable, ampicillin, gentamicin, trimethoprim/sulfamethoxazole, or quinolones can be indicated. A vaccine for
Salmonella typhi
is available.
References for PCR primers for food testing
:
[
547
,
551
]
Infection
:
Shigella
(bacterium)
Treatment
:
Supportive care; trimethoprim/sulfamethoxazole is indicated in the United States if the bacterium is susceptible; nalidixic acid or other quinolones are recommended if the bacterial species is resistant, which may be the case in developing countries.
References for PCR primers for food testing
:
[
547
]
Infection
:
Staphylococcus aureus
(bacterium)
Treatment
:
Supportive care
References for PCR primers for food testing
:
[
551
]
Infection
:
Taenia saginata
(beef tapeworm)
Treatment
:
Niclosamide or praziquantel
References for PCR primers for food testing
:
[
558
,
559
]
Infection
:
Taenia solium
(pork tapeworm)
Treatment
:
Niclosamide or praziquantel; infection of the central nervous system (brain) may require surgery.
References for PCR primers for food testing
:
[
559
]
Infection
:
Toxoplasma gondii
(single-celled parasite)
Treatment
:
Asymptomatic people do not need treatment. Spiramycin or pyrimethamine plus sulfadiazine may be used for immunocompromised persons. Pyrimethamine combined with sulfadiazine (with or without steroids) may be indicated for ocular disease. Folinic acid is recommended with sulfadiazine plus pyrimethamine to counteract suppression of bone marrow.
References for PCR primers for food testing
:
[
560
]
Infection
:
Trichinella spiralis
(intestinal roundworm, larvae can form cysts in various muscles of the body)
Treatment
:
Supportive care combined with albendazole or mebendazole.
References for PCR primers for food testing
:
[
541
]
Infection
:
Vibrio cholerae
(bacterium)
Treatment
:
Supportive care with copious oral and intravenous rehydration; if cholera is confirmed, tetracycline or doxycycline is indicated for adults and trimethoprim/sulfamethoxazole for children under 8.
References for PCR primers for food testing
:
[
547
,
561
]
Infection
:
Vibrio parahaemolyticus
(bacterium)
