Fundamental Food Microbiology, Third Edition - Fuad Fathir

412 FUNDAMENTAL FOOD MICROBIOLOGY
A. Trichinosis by Trichinella spiralis
Trichinella spiralis is a roundworm and can be present in high frequencies in pigs
feeding on garbage. It is also found quite frequently among game animals. A person
gets infected by consuming raw or insufficiently cooked meat of infected animals.
The infected meat contains encysted larvae. Once the meat is consumed, the cysts
dissolve in the GI tract, releasing the larvae, which then infect the GI tract epithelium.
Here, the parasites mate and deposit larvae in the lymphatic system. Through lymphatic
circulation, the larvae infect other body tissues. In the U.S., between 1973
and 1987, 128 incidents of trichinosis infecting 843 people were recorded. Although
many types of foods were involved, the highest incidence (55) was from pork. Almost
all incidences were due to improper cooking.
The symptoms of trichinosis appear in 2 to 28 d following ingestion. Initial
symptoms are nausea, vomiting, and diarrhea, followed by fever, swelling of eyes,
muscular pain, and respiratory difficulties. In extreme cases of infection, toxemia
and death may result.
The prevention methods consist of not raising pigs on garbage and cooking meat
thoroughly [140�F (60�C) and above]. Microwave cooking may not be effective in
killing all the larvae. Freezing meat for 20 d at –20�C (home freezer) or in liquid
nitrogen for several seconds also kills the parasite. 9,11
B. Anisakiasis by Anisakis simplex
The nematode Anisakiasis simplex is a parasite in many fish, particularly of marine
origin. Human infection results from the consumption of raw infected fish. Inadequately
cooked, brined, or smoked fish has also been implicated in some cases.
Symptoms appear after a few days and generally include irritation of throat and
digestive tract. Anisakiasis is predominant in countries where raw fish is consumed.
Proper cooking, salting, or freezing at –20�C for 3 d can be used as a preventative
measure. 12
C. Taeniasis by Taenia spp.
Taeniasis is a tapeworm disease caused by Taenia solium from pork and by Tae.
saginata from beef. The illness results from the ingestion of raw or improperly
cooked meat contaminated with larvae of the tapeworms. Symptoms appear within
a few weeks and are digestive disorders. If an organ is infected by the larvae,
especially a vital organ, the consequences can be severe. 13
D. Toxoplasmosis by Toxoplasma gondii
Toxoplasmosis is a tissue protozoan disease transmitted to humans from the consumption
of undercooked and raw meat and raw milk contaminated with oocysts of
Toxoplasma gondii. Contamination of food with feces, especially from cats, can also
be involved. In many people, it does not cause any problems. However, in individuals