Research seminar 8.9.2009: Calf diarrhoea and cryptosporidiae
Senior Researcher Tiina Autio, Production Animal Health Research Unit, Kuopio
Evira/Helsinki Viikki, Mustialankatu 3, Auditorium C111 Kalevi
Tu 8.9.2009, 3:00 – 4:00 pm
Cryptosporidiae are common parasites among people, and domestic and wild animals.
Human cryptosporidiosis most frequently is self-limited watery diarrhoea. Other symptoms also may occur, e.g. abdominal pain, slight fever and nausea, and the disease may persist for weeks. To persons with immune deficiency it may be serious, even fatal.
Faeco-oral infection occurs via swimming water, drinking water or food contaminated by faeces from people or animals. Direct infections from other persons or animals also are known. In bovines cryptosporidiosis (caused by C. parvum) occurs as calf diarrhoea. Typical diarrhoea caused by cryptosporidiae has foul stench, is watery and rich, and seen in one to two-week old calves.
Research in several countries has demonstrated that cryptosporidiae generally are found in calves, and these are considered a major reservoir. Studies have shown cases being most frequent at the age of two weeks. In recent years research has concentrated on defining the extent of various species and their related subspecies. Bovine cryptosporidiae cannot with certainty be differentiated morphologically from each other, and to separate different species from each other, sequencing of the SSU rRNA region or a PCR-RFLP technique is being used.
Several studies have shown that zoonotic
C. parvum is most frequent in small calves younger than two months, while
C. bovis and
C. ryanae dominate in older calves. Also mixed infections are common and diagnostically challenging.
In Finland, cryptosporidiae have been analyzed in faecal samples from healthy claves that were collected during various projects, and in clinical samples of calf diarrhoea. In later years species definitions have been done on new as well as older existing samples (SSU rRNA PCR-RFLP).
Lesser amounts of cryptosporidiae generally were found in healthy calves at calf rearing units (in 2001-2007). Most frequent species are C. bovis and C. ryanae, while C. parvum was not found in 63 samples typed. Neither was C. parvum found in calves at large dairy farms (in 2002-2008) when seventeen faecal samples were analysed.
A study in 2009 on beef cow farms , six farms were sampled for the presence of cryptosporidiae. Two farms had calf diarrhoea from rotavirus. Cryptosporidiae also was found, but eighteen positive samples only revealed apathogenic species.
By analyses in Finland (Evira, Kuopio) for calf diarrhoea, all samples from calves younger than two months are analyzed for cryptosporidiae. Significant amounts of cryptosporidiae rarely are found. Preserved (from 2003-) ZN staining positive samples have been analyzed for species of cryptosporidiae. Most frequent were apathogenic species C. bovis and C. ryanae. C. parvum has been found at nine farms. Seven of these findings were made in the last two years. Most of the farms have other diarrhea causing agenst, e.g. rotavirus and Eimeria. Two of the farms were dairy farms and the rest beef cow farms.
C. parvum can be divided into several subtypes. The most common method of subtyping C. parvum is analyzing with the gp60 sequence, by which they can be divided into subfamilies (IIa, IIb, IIc etc.) and subtypes (e.g. IIaA16G1R1). C. parvum parasites isolated from bovines usually belong to subfamily IIa and lesser to IId and IIl. One subtype IIaA15G2R1 particularly is common and in several countries appears in bovines as well as people. Geographic variations in the presence of separate subtypes have been found.
A total of eight samples of C. parvum from six farms have been subtyped with the gp60 sequence. Four farms showed presence of types of the subfamily IIa (two different subtypes) and two farms had types of mutually different subfamilies IId. To date, the subtype IIaA15G2R1 existing in several countries has not been found. Subtypes found here in calves have been found in domestic animals and/or people in other countries.
Lecture is in Finnish.
Senior Researcher Tiina Autio, Production Animal Health Research Unit, Kuopio,
tel. 02077 24955, tiina.autio evira.fi