Patterns of Cryptosporidium antigen and oocyst excretion in calves studied by reverse passive haemagglutination and light microscopy

Cryptosporidiosis in people: it's not just about the cows

Cryptosporidiosis is one of the most common causes of infectious diarrhea in people. Although dairy calves are high-risk hosts, the role of other livestock, pets, and humans in the disease should not be underestimated. Some Cryptosporidium species and strains are specific to people, others are specific to animals while some are zoonotic pathogens. Cryptosporidium hominis is the species responsible for the majority of human cases in the United States, Sub-Saharan Africa, and Asia, while Cryptosporidium parvum accounts for more human cases in Europe and particularly in the United Kingdom. A deeper understanding of Cryptosporidium host range, reservoirs, and transmission is needed to develop preventive strategies to protect the general public.

In vivo encystation of Blastocystis hominis

Blastocystis from infected stools of a person who showed chronic symptoms of abdominal discomfort and diarrhea were examined over a 6-month period, using transmission electron microscopy, for the ultrastructural changes from vacuolar to cystic stage. The study confirms the irregular shedding phenomenon of the organism previously reported, and for the first time, records sequential changes in encystation in stools collected over a time period. The study also confirms the existence of a precystic stage which has an immature cell wall consisting of a layer of a homogenous electron-dense mass surrounding the cell which acts as a intermediatory stage between the vacuolar and cystic stage.

Herd-level risk factors for Cryptosporidium infection in dairy-goat kids in western France

We conducted a cross-sectional study of risk factors for herd-level kid positivity for Cryptosporidium parvum oocysts in dairy-goat farms (Deux-Sèvres, western France). From January to March 2003, faeces from a convenient sample of 879 5- to 30-day-old goat kids from 60 herds were examined microscopically after staining with carbol fuschin. Oocyst shedding was scored semi-quantitatively (0 to 4+) allowing us to obtain a cumulative score per herd. Standardized questionnaires with information about management practices were collected in each farm. We found positive kids in 32 of 60 herds (53.3%) and in 142 animals out of 879 (16.2%). We used logistic regression for two risk-factor model: (1) simple positive (case: herd score > or = 1+, at least one positive kid in the herd, versus control: herd score=0), (2) strongly positive (case: overall herd score > or = 3+ versus control: herd score <3+). Risk factors associated with simple positive herds were period of sampling compared to the peak of births (After versus Before, OR=4.2, 95% CI 1.2, 15.3) and practice of kid grouping by age or weight (Yes versus No, OR=4.4, 95% CI 1.0, 19.1). Risk factors associated with strongly positive herds were period of investigation (February/March versus January, OR=12.7, 95% CI 2.1, 76.6), exposure to graminaceous plants in forage (OR=11.6, 95% CI 1.7, 81.0) and type of ventilation in the goat premises (Vertical versus Wind effect, OR=14.7, 95% CI 2.1, 106.1). No important association was found between kid-management practices and herd positivity. These results suggest a major role of the environment of kids during their first hours of life in the adult-goat premises regarding the transmission of C. parvum infection.

Prevalence of Cryptosporidium infection in calves in France

Two multicentre surveys were conducted in France to estimate the prevalence of Cryptosporidium infection in calves using qualitative ELISA for detection of Cryptosporidium coproantigens and oocysts. The first survey involved 4-12-day-old calves in six dairy-calf distribution centres, collecting calves from seven Administrative Regions (Aquitaine, Bretagne, Franche-Comté, Lorraine, Normandie, Nord, Pays de Loire). For each region, 20 calves were selected every month for 12 consecutive months (October 1995-September 1996). Prevalence of Cryptosporidium infection was 17.9% (Confidence Intervals (C.I.) 95%=[16.1%; 19.8%]) among the 1628 selected calves, of which only 5.3% had diarrhoea. The second survey conducted between November 1995 and May 1996 involved 4-21-day-old calves examined by veterinary practitioners who selected 189 livestock farms of dairy- or suckler-type in ten Administrative Departments (Allier, Cantal, Creuse, Doubs, Ille-et-Vilaine, Maine-et-Loire, Manche, Pas-de-Calais, Saône-et-Loire, Vendée). Cryptosporidia were detected in 105 (55.6%) of the farms. Among the 440 calves examined, of which 398 (90.5%) presented diarrhoea, cryptosporidia were found in 191 animals, i.e. a prevalence of 43.4% (C.I. 95%=[38. 8%; 48.0%]). Breed of calves and type of housing had very little impact on prevalence in this survey. Some regional variations could be noticed, even if cryptosporidia infection is widespread. Monthly variations could be related to seasonal peaks in calving with a lower infection rate during summer.