A Perspective on Cryptosporidium and Giardia, with an Emphasis on Bovines and Recent Epidemiological Findings

Abstract

Cryptosporidium and Giardia are two common aetiological agents of infectious enteritis in humans and animals worldwide. These parasitic protists are usually transmitted by the faecal-oral route, following the ingestion of infective stages (oocysts or cysts). An essential component of the control of these parasitic infections, from a public health perspective, is an understanding of the sources and routes of transmission in different geographical regions. Bovines are considered potential sources of infection for humans, because species and genotypes of Cryptosporidium and Giardia infecting humans have also been isolated from cattle in molecular parasitological studies. However, species and genotypes of Cryptosporidium and Giardia of bovids, and the extent of zoonotic transmission in different geographical regions in the world, are still relatively poorly understood. The purpose of this article is to (1) provide a brief background on Cryptosporidium and Giardia, (2) review some key aspects of the molecular epidemiology of cryptosporidiosis and giardiasis in animals, with an emphasis on bovines, (3) summarize research of Cryptosporidium and Giardia from cattle and water buffaloes in parts of Australasia and Sri Lanka, considering public health aspects and (4) provide a perspective on future avenues of study. Recent studies reinforce that bovines harbour Cryptosporidium and Giardia that likely pose a human health risk and highlight the need for future investigations of the biology, population genetics and transmission dynamics of Cryptosporidium and Giardia in cattle, water buffaloes and other ruminants in different geographical regions, the fate and transport of infective stages following their release into the environment, as well as for improved strategies for the control and prevention of cryptosporidiosis and giardiasis, guided by molecular epidemiological studies.

Prevalence and Determinants of Cryptosporidium Infection in an Underdeveloped Rural Region of Southwestern China

“…11,20,21 The high prevalence of Cryptosporidium infection documented in our study may be due to poor sanitation, poverty, and lack of diagnostic tools. 3,22 Since our study was performed in late summer and early autumn, these results might also reflect the seasonality of Cryptosporidium transmission. [23][24][25] We noted that the prevalence of Cryptosporidium was different among the towns and therefore carried out a stratified analysis.…”

“…Previous studies also found that raising cattle, especially calve, was a risk factor for human Cryptosporidium infection. 3,31 In this area, cattle usually graze on the nearby hills away from human settlements, thus human-cattle contacting is less frequent. Horses, cats, and dogs are primarily infected with host-specific Cryptosporidium species or genotypes, and therefore, the actual risk of zoonotic transmission of these animals may be low.…”

Comparative evaluation of conventional staining method and enzyme linked immunosorbent assay kits for the detection of bovine cryptosporidiosis

“…Cryptosporidiosis is an important insidious disease of wide variety of animals, including humans, caused by apicomplexan protozoa of the genus Cryptosporidium (Abeywardena et al, 2015). Till date, 26 Cryptosporidium species and more than 70 genotypes have been recognized (Qi et al, 2015) and among them the most important species infecting bovines are C. parvum, C. andersoni and C. bovis (bovine genotype B) (Mirhashemi et al, 2016).…”

Detection of zoonotic and livestock-specific assemblages of Giardia duodenalis in free-living wild lizards

“…Most Giardia infections naturally occurring in wildlife are caused by zoonotic species, which are considered to have been introduced into wildlife habitats and, once established, maintained by direct contact or environmental routes (THOMPSON, 2013;ABEYWARDENA et al, 2015). The study region (Galicia, northwest Spain) is characterized by an important livestock sector and extensive rural areas, where farmers usually applied slurry as manure in the grasslands.…”