Abstract

Of 1346 faecal samples from the Chikwawa and Thyolo districts of Malawi, analysed for the presence of Cryptosporidium oocysts between October 2001 and May 2003, 61.3% were from cattle (29.8% of these were from calves <6 months old). Cryptosporidium oocysts were detected during all three seasons studied in Chikwawa and Thyolo. In Chikwawa, 13.6% of adult cattle and 11.7% of calves were infected, compared to 28.9% of adult cattle and 36.7% of calves in Thyolo. Dependent on season, between 7.8% and 37.7% (Chikwawa) and 16.7% and 39.3% (Thyolo) of cattle samples contained oocysts. In Chikwawa, the highest percentage of infections occurred in the cool season, whereas in Thyolo, the highest percentage of infections occurred in the dry season. Faecal samples from goats [n=225], pigs [n=92], sheep [n=6]), rabbits, guinea pigs, chickens, ducks, turkeys, doves and guinea fowls were also analysed. Up to 5.6% of goat samples contained oocysts in Chikwawa, compared to between 16.7% and 39.3% in Thyolo. Again, in Chikwawa, the highest percentage of infections occurred in the cool season and the lowest in the rainy season, whereas, in Thyolo, the highest percentage of infections occurred in the dry season and the lowest in the cool season. In pigs, more infections were detected in the dry season in Chikwawa, but infections in the cool season were similar (17.7%), whereas in Thyolo, infections occurred in all three seasons (17.9% in the rainy season, 25% in the cool season and 60% in the dry season). Of ten diarrhoeic, oocyst positive cattle faecal samples collected from Chikwawa and subjected to PCR-RFLP, four oocyst positive samples (two from heifers, one from a cow and one unknown) were amplified at an 18S rRNA and Cryptosporidium oocyst wall protein (COWP) loci. RFLP of the 18S rRNA locus indicated that Cryptosporidium parvum, Cryptosporidium hominis, Cryptosporidium bovis and/or Cryptosporidium ryanae DNA, or a mixture of them was present. Cryptosporidium parvum DNA was identified in one sample that amplified at the COWP locus, indicating the presence of the major zoonotic Cryptosporidium species in Malawi.

Highlights

  • IntroductionIn humans in­ habiting many regions of the world, Cryptosporidium constitutes part of the complex group of parasitic, bacterial and viral diseases that impair the ability to achieve full potential and impair development and socio-economic improvements

  • The apicomplexan parasite, Cryptosporidium, is re­ sponsible for many outbreaks of human diseaseDepartment of Environmental Health, University of Malawi, Polytechnic, Private Bag 303, Chichiri, Blantyre 3, MalawiScottish Parasite Diagnostic Laboratory, Stobhill Hospital, Glasg­ ow G21 3UW, Scotland, United KingdomEnvironmental Health, Department of Civil Engineering, Glas­ gow G4 ONG, Scotland, United KingdomAccepted for publication 6 April 2009—Editor affect­ing both immunocompetent and immunocom­ promised individuals (Cacciò, Thompson, McLauch­ lin & Smith 2005)

  • 905 were from Chikwawa consisting of 559 samples collected in the dry season, 189 in the rainy season and 157 in the cool season, and 441 sam­ ples were from Thyolo consisting of 219 samples collected in the dry season, 114 in the rainy season and 108 in the cool season

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Summary

Introduction

In humans in­ habiting many regions of the world, Cryptosporidium constitutes part of the complex group of parasitic, bacterial and viral diseases that impair the ability to achieve full potential and impair development and socio-economic improvements. Of the 21 recognised Cryptosporidium species, hu­ mans can be infected with Cryptosporidium parvum, Cryptosporidium hominis, Cryptosporidium melea­ gridis, Cryptosporidium felis, Cryptosporidium muris, Cryptosporidium canis, Cryptosporidium suis and the Cryptosporidium cervine, monkey, skunk and rabb­ it genotypes (Caccio et al 2005; Nichols, Chal­ m­ers, Sopwith, Regan, Hunter, Grenfell, Har­rison & Lane 2006), but two species, C. parvum and C. ho­ minis, cause the majority of human disease (Caccio et al 2005). Cryp­tos­ poridium par­vum cryptosporidiosis is a cause of scours in young, unweaned livestock, and is the species rec­ ognized for having the greatest zoonotic potential

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