Focus of human trichinellosis in Papua New Guinea

Human trichinellosis and teniasis (Taenia solium) are meat-borne helminthic infections with a wide distribution throughout the world. However, there is little information on the prevalence of these infections in Papua New Guinea. In 1999, serum samples were collected from 97 people in 6 villages in the remote Bensbach area of Papua New Guinea. Enzyme-linked immunosorbent assay and Western blot analyses were used to detect anti-Trichinella immunoglobulin (Ig) G and anti-cysticercus IgG in this population. The prevalence of Trichinella antibodies among inhabitants of the Bensbach area was 28.9% (28 of 97; 67.8% in men), suggesting a high consumption of poorly cooked meat. The higher prevalence of infection for Trichinella in men compared with women may be explained by the inclination of men to eat undercooked pork while hunting. All serum samples were negative for cysticercus antibodies. This is to our knowledge the first serosurvey showing anti-Trichinella antibodies in a human population living in Papua New Guinea (Australian region).

Horse trichinellosis, an unresolved puzzle

In spite of routine controls to detect Trichinella larvae in horse-meat, human infections due to horse-meat consumption continue to occur in France and Italy. The epidemiology of horse trichinellosis since its discovery in 1975 is outlined, addressing the possible modes of natural transmission to horses, the need to develop more sensitive methods for detecting Trichinella larvae in horses, and the economic impact of horse trichinellosis. Investigations of human outbreaks due to horse-meat consumption have implicated single cases of inadequate veterinary controls on horses imported from non-European Union countries. In particular, most cases of human infection have been attributed to horses imported from Eastern Europe, where pig trichinellosis is re-emerging and the main source of infection in horses.

An expected outbreak of human trichinellosis for the consumption of horsemeat

In late February 1998, an outbreak of human trichinellosis occurred in the town of Piacenza (northern Italy) among 92 persons who had eaten raw horsemeat. The source of infection was a horse imported to the abattoir of Brescia one month previously. Although the horse had been found to be positive for trichinellosis upon routine examination, the head of an uninfected horse was exchanged with the head of the infected animal, which was mistakenly placed on the market.

Failure of mebendazole in the treatment of humans with Trichinella spiralis infection at the stage of encapsulating larvae

Trichinella spiralis larvae infective for laboratory mice were collected from muscle biopsies performed at different times (from 1 day to 16 months) following the end of treatment, indicating the failure of mebendazole to kill Trichinella parasites when they are encapsulating in muscles.

Trichinella pseudospiralis outbreak in France

Four persons became ill with trichinellosis after eating meat from a wild boar hunted in Camargue, France. Nonencapsulated larvae of Trichinella pseudospiralis were detected in meat and muscle biopsy specimens. The diagnoses were confirmed by molecular typing. Surveillance for the emerging T. pseudospiralis should be expanded.

Identification and characterisation of three antigenic proteins from Cryptosporidium parvum sporozoites using a DNA library expressing poly-histidine tagged peptides

To identify antigenic peptides of the parasite Cryptosporidium parvum, an expression library that allows for the production of chimeric proteins fused with a 6-histidine tag was made. The library was screened with C. parvum sporozoite rabbit anti-serum, and three positive clones (sa20, sa35, and sa40) were identified. The corresponding recombinant proteins (SA20, SA35, and SA40) were expressed in Escherichia coli and purified by metal-affinity chromatography. The sequence of sa20 and sa35 clones did not show any homology with known genes or proteins, whereas the 5' end of the sa40 clone showed homology with two previously identified C. parvum sequences. Hybridisations to intact chromosomes fractionated by pulsed-field gel electrophoresis revealed that the sa35 and sa40 sequences are localised on chromosome VII, whereas the sa20 sequence is localised on chromosome VI. Reverse transcriptase-PCR experiments showed the presence of mRNAs for sa35 and sa40 in the oocyst, whereas the sa20 mRNA was undetectable in this stage. The serological response to the three proteins was assayed in C. parvum-immunised rabbits and in immunocompetent individuals with cryptosporidiosis. The Western blot results indicated that rabbits, challenged with a sporozoite crude antigen or with an oocyst crude antigen, were highly responsive to these three antigens. Human serum samples showed a response to the three proteins, although the response to SA20 appeared to be unrelated to a recent C. parvum infection. These results suggest that the SA35 and the SA40 proteins may be useful in detecting C. parvum infections.

Long-term survival of Cryptosporidium parvum oocysts in seawater and in experimentally infected mussels (Mytilus galloprovincialis)

Transmission of infectious oocysts of Cryptosporidium parvum via surface- and drinking-water supplies has been reported and many surface waters flow into the sea, potentially causing runoff of animal-infected faeces. Eating raw mussels is a common practice in many countries, increasing the public's risk of acquiring enteric pathogens. The aims of the present study were to estimate how long C. parvum oocysts remain infectious in artificial seawater, to determine if the oocysts are retained in mussel tissues (Mytilus galloprovincialis), and how long they maintain their infectivity. Oocysts were incubated in artificial seawater at 6-8 degrees C under moderate oxygenation and the infectivity of oocysts was tested five times, over a 12 month period after incubation in seawater, in BALB/c mice. Each pup was inoculated per os with 10(5) oocysts and killed 5 days p.i. Oocysts remained infectious for 1 year. Forty mussels held in an aquarium containing artificial seawater filtered out more than 4 x 10(8) oocysts in a 24 h period. Oocysts were detected in the gill washing up to 3 days p.i., in the haemolymph up to 7 days p.i., and in the intestinal tract up to 14 days p.i. Oocysts collected from the gut of mussels 7 and 14 days p.i. were observed to have infected mice. These results suggest that C. parvum oocysts can survive in seawater for at least 1 year and can be filtered out by benthic mussels, retaining their infectivity up to 14 days, so seawater and molluscs are a potential source of C. parvum infection for humans.

Gastric involvement in AIDS associated cryptosporidiosis

BACKGROUND

Cryptosporidiosis has been shown to be a common cause of diarrhoea in both immunocompetent and immunosuppressed individuals. There are very few data on the distribution of Cryptosporidium parvum along the gastrointestinal tract.

AIMS

To evaluate the location of Cryptosporidium parasites in the digestive tract of patients with AIDS.

METHODS

Gastrointestinal localisation of C parvum was studied in 71 patients with AIDS who underwent upper and/or lower endoscopy with biopsy for chronic diarrhoeal illness and/or other gastrointestinal disorders of unexplained origin.

RESULTS

Twenty four individuals (33.8%) were positive for C parvum, of which 16 (88.9%) had parasites in the gastric epithelium. Most patients with gastric localisation of C parvum did not show specific symptoms indicating the presence of this parasite in the stomach.

CONCLUSIONS

Gastric involvement in AIDS related cryptosporidiosis is more frequent than expected, but no clear correlation between gastric location and related clinical and pathological features was observed.

Identification of a human isolate of Encephalitozoon cuniculi type I from Italy

A microsporidial strain, obtained from a person with AIDS living in Italy was isolated and cultivated on RK13 (rabbit kidney) cell monolayers. Identification at the species level was performed by immunological and molecular methods. Western blot analysis showed that the human isolate and the Encephalitozoon cuniculi reference strain had similar banding patterns. The small subunit rRNA sequence analysis confirmed the identification of the isolate as E. cuniculi, which is a widespread microsporidian species infecting a wide range of natural hosts, including humans. Moreover, based on the sequence of the rDNA internal transcribed spacer region, this isolate was classified as E. cuniculi type I (rabbit strain), previously reported in six persons with AIDS living in Switzerland. These results provide further information on the geographical distribution of E. cuniculi types.

Human outbreak of trichinellosis associated with the consumption of horsemeat in Italy

Trichinellosis is endemic among sylvatic mammals in Italy, though it causes only few infections in humans, usually due to the consumption of pork from pigs grazing in wild areas or from wild boars. Most cases of human trichinellosis in Italy are due to th

Distribution of Trichinella spiralis larvae in muscles from a naturally infected horse

Epidemiological investigations conducted during 10 trichinellosis outbreaks between 1975 and 1994 showed that horse-meat was the probable source of infection. Though hundreds of thousands of horses have been examined at abattoirs in America and Europe to detect Trichinella infection by artificial digestion or trichinelloscopy, an infected horse has never been detected during routine analysis, which consists of examining 1 g of tissue muscle from the diaphragm. In November 1996, a naturally infected horse imported from Romania was detected in Southern Italy. The parasite was identified as Trichinella spiralis by random amplified polymorphic DNA analysis. Artificial digestion of tissue samples from 60 different muscles from 13 different sites of the infected horse carcass showed that M. levator Labii maxillaris, M. hyoideus transversus, and M. buccinator were the 3 most infected muscles. Muscles from the tongue, the masseter, and the diaphragm, which have normally been considered the muscles of choice for diagnosis, were the 4th, 6th and 13th most infected muscles, respectively. When comparing body sites, muscle tissues from the head showed the highest level of infection, followed by muscles from the neck. This finding may explain the negative results that have been obtained in the past during routine examination of the diaphragm of horses.

First outbreak of human trichinellosis caused by Trichinella pseudospiralis

This is the first report of an epidemic of human infection with Trichinella pseudospiralis. An outbreak of trichinellosis affecting 59 individuals, of whom one died, occurred in southern Thailand during 1994-1995. The source of this epidemic was raw pork from a wild pig that was distributed to villagers by a local hunter. The most striking clinical features among 50 individuals who could be followed were muscular swelling, myalgia, and asthenia persisting for > 4 months. These were associated with significant elevations of creatine phosphokinase and lactate dehydrogenase levels. All patients had Trichinella-specific IgG antibodies in an enzyme-linked immunosorbent assay. Muscle biopsies, performed in six cases, showed nonencapsulated, actively migrating Trichinella larvae. Experimental infection of mice with larvae from human biopsies revealed nonencapsulated muscle larvae consistent with T. pseudospiralis. The identification of muscle larvae from a human specimen by random amplified polymorphic DNA analysis confirmed the causative agent to be T. pseudospiralis. Patients seemed to respond best to treatment with albendazole.

Detection of Trichinella spiralis in a horse during routine examination in Italy

Routine examination for Trichinella infection by artificial digestion of 5-g samples of muscle tissue revealed the presence of muscle larvae in one out of 28 horses imported from Romania to an abattoir in Italy. The parasite, identified as Trichinella spiralis by the polymerase chain reaction, showed a reproductive capacity index of 68 in Swiss mice. Light microscope examination of 200 nurse cell-larva complexes showed that 22% of them were calcified and that the capsules of the non-calcified nurse cells were 17.5-27.5 microns (s = 22.67 microns) thick and had very few cellular infiltrates. The serum samples from the parasitologically positive horse and from three other horses of the same stock, from which Trichinella larvae were not recovered by digestion, showed a low level of positivity as determined by ELISA and Western blot analyses using a crude antigen, whereas negative results were observed in both tests when an excretory-secretory antigen was used. The results, together with data from the literature, suggest that the horse had acquired the infection 8-10 months previously and confirm earlier observation obtained from experimental infections, which showed that muscle worm burden and specific circulating antibodies were lost several months after infection.

Clinical cryptosporidiosis and human immunodeficiency virus (HIV)-induced immunosuppression: findings from a longitudinal study of HIV-positive and HIV-negative former injection drug users

The natural history of cryptosporidiosis was investigated during a waterborne outbreak among 1731 members of a drug rehabilitation community in Italy; 19.6% of the members were positive for human immunodeficiency virus (HIV). Demographic and clinical information and pre-outbreak serum samples were available. Clinical data were analyzed, stratifying the study population by HIV serostatus and CD4 cell count. The attack rate of clinical cryptosporidiosis was 13.6% among HIV-negative individuals and 30.7% among HIV-positive individuals, although in the latter, it varied according to CD4 cell count. Clinical symptoms and their duration were also related to CD4 cell count. Chronic symptoms were observed in only 16 individuals (15.4%), who all had <150 CD4 cells at the onset of the illness. Among a systematic sample of 198 individuals, 14.1% already had anti-Cryptosporidium antibodies before the outbreak, and 51.2% developed specific antibodies during the outbreak. The development and clinical manifestations of cryptosporidiosis were strongly influenced by the level of HIV-induced immunosuppression.

[Development of an immunoenzyme test for the diagnosis of human cysticercosis using a heterologous antigen]

Serological tests for the immunodiagnosis of human cysticercosis (an indirect ELISA test) and for the detection of Taenia solium antigen(s) in liquor samples (a sandwich ELISA test) have been developed using a heterologous antigen from the cyst fluid of T. hydatigena. Antibodies to T. solium were detected in 20 Italian subjects out of 113 with cerebral lesions of unknown etiology, and T. solium antigen(s) were detected in three of them, from 1991 to 1994. Case history of the positive patients showed that 17 of them probably acquired the infection in Italy. These results point out that cysticercosis is still present in Italy, and physicians have to consider this helminthic infection in a differential diagnosis.