Evaluation of the U.S. Food and Drug Administration validated molecular method for detection of Cyclospora cayetanensis oocysts on fresh and frozen berries.

Outbreaks and sporadic cases of Cyclospora cayetanensis have been linked to consumption of berries. The efficacy of the U.S. Food and Drug Administration (FDA) method for detection of C. cayetanensis was evaluated in fresh berries (blackberries, strawberries, blueberries and mixed berries) and in frozen mixed berries. The protocol included seeding with C. cayetanensis oocysts, produce washing, DNA extraction and a dual TaqMan assay. As few as five oocysts were detected in every type of fresh berry analyzed. All berry samples seeded with 200 oocysts were positive and all unseeded berry samples were negative. No significant differences were observed among any of the berry types analyzed in detection rates, CT values and estimated oocyst recovery percentages. Mixed berries were seeded and frozen for up to seven weeks. As few as five oocysts were also detected. No significant differences were observed in C. cayetanensis CT values between fresh and frozen mixed berries at any seeding level. In conclusion, the FDA BAM Chapter 19B method for the detection of Cyclospora was robust, consistent, and showed high sensitivity in all types of berries analyzed. Evaluation of the FDA detection method in berries will provide reliable laboratory support for surveillance programs and for outbreak investigations.

The epidemiology of trichinellosis in the Arctic territories of a Far Eastern District of the Russian Federation.

Trichinellosis, a zoonotic disease caused by nematodes of the genus Trichinella, is still a public health concern in the Arctic. The aims of this study were to investigate the seroprevalence of anti-Trichinella IgG in aboriginal peoples of two settlements in the Chukotka Autonomous Okrug (Russian Federation) on the Arctic coast of the Bering Sea, and to evaluate the survival of Trichinella nativa larvae in local fermented and frozen meat products. A seroprevalence of 24.3% was detected in 259 people tested by an enzyme-linked immunosorbent assay (ELISA). The highest prevalence was detected among people who consumed traditional local foods made from the meat of marine mammals. Trichinella nativa larvae were found to survive for up to 24 months in a fermented and frozen marine mammal meat product called kopalkhen. Since the T. nativa life cycle can be completed in the absence of humans, it can be expected to persist in the environment and therefore remain a cause of morbidity in the human populations living in Arctic regions.

Myxosporean infection in frozen blocks of Patagonian hakes.

Numerous pseudocysts of the myxosporean genus Kudoa were found infecting the body musculature of commercial frozen blocks of Patagonian hakes of the species Macruronus magellanicus, Merluccius australis, and Merluccius hubbsi. Pseudocysts consisted of numerous diminutive quadrate spores with four polar capsules. The small subunit ribosomal DNA was amplified, cloned, and sequenced for phylogenetic study. Minimum evolution and maximum parsimony analyses placed the resulting sequences in a clade with Kudoa species of Patagonian hakes, K. rosenbuschi and K. alliaria, with bootstrap values of 99%. Molecular and morphological results indicated that the above species were the same, with some differences based on host-related factors. Minor muscular damage appeared as a focal distortion of host fiber architecture to accommodate the parasite. The mild host response consisted of different stages of encapsulation. In cases of concurrent heavy infections, these fish are unappealing as food, due to the parasite's potential effect on the market's perception of macroscopic, unsightly cysts in fish musculature.

Human trichinellosis due to Trichinella britovi in southern France after consumption of frozen wild boar meat.

Six patients were infected with Trichinella britovi in southern France following consumption of frozen wild boar meat, which had been frozen at -35 degrees C for 7 days. Microscopic examination of a sample of frozen wild boar muscle revealed the presence of rare encapsulated Trichinella larvae, identified as T. britovi. People eating wild boar must follow individual prophylactic rules such as efficient cooking of meat (at least 65 degrees C at the core for 1 minute) as recommended by the International Commission on Trichinellosis, or freezing exceeding four weeks at -20 degrees C.

Protozoal contamination of water used in Thai frozen food industry.

This study evaluated the prevalence of contamination of water that was used for food preparation. Since protozoal cysts can be found in small numbers in water, 1,000 liters of either untreated or treated water were filtered through activated carbon block filters (1 microm nominal porosity). Identification of protozoa was performed using specific monoclonal antibodies against Giardia and Cryptosporidium parasites followed by fluorescence microscopy. Twelve of 20 untreated water samples (60%) were found to be contaminated by Giardia cysts, with an average of 53.33 cysts/1,000 liters (geometric mean 39.43), whilst 7 samples (35%) were contaminated by Cryptosporidium oocysts, with an average of 28.57 oocysts/1,000 liters (geometric mean 26.92). Three samples of untreated water (15%) were positive for both organisms. In contrast, none of the treated water samples were contaminated.

Viability of metacercariae of Clonorchis sinensis in frozen or salted freshwater fish.

Metacercariae of Clonorchis sinensis were collected from freshwater fish (Pseudorasbora parva) after storage in a freezer at -12 degrees C for 10-20 days, in a freezer at -20 degrees for 3-7 days, or treating with heavy salt (fish/salt = 10 gm/3 gm) at 26 degrees for 5-15 days. The metacercariae from the frozen fish were inoculated into 30 rats and eight rabbits, and those from the salted fish into 33 rats. Metacercariae from freshwater fish stored at -12 degrees for 10-18 days or -20 degrees for 3-7 remained viable and infective. Moreover, those kept at the heavy salt concentration for 5-7 days remained viable and infective. These findings indicate that freezing or storing infected freshwater fish in heavy salt may not be effective in the prevention of clonorchiasis. However, it appears that refrigeration, or keeping the fish in salt for longer periods, may be suitable for prevention of the infection.