Overview of Waterborne Pathogens - Waterborne Pathogens: Detection Methods and Applications - page 18

public health viewpoint. There are seven groups incorporating additional
subgroups. For information on progress toward a rotavirus vaccine, see the
2007 review in Nature Reviews Microbiology by Angel et al. 17
Patients typically shed 10 11 virus particles per gram of feces for a period
of eight days. Therefore, it is unsurprising that rotavirus has been found in
large numbers in sewage and both source and treated waters.
2.1.7. Sapovirus
Like NoV, this is a member of the caliciviruses and causes acute gastro-
enteritis in all age groups. Sapovirus usually displays the typical calicivirus
morphology. Little is known about its prevalence worldwide.
2.2. BACTERIA
Bacteria are prokaryotic microorganisms of typically a few microns
in size. They are bigger than most viruses but smaller than most protozoa
and helminths. There is extraordinary diversity in the bacterial kingdom,
with a wide range of morphologies exhibited by different bacterial species
( Fig. 2.5 ). There are typically a million bacteria in every milliliter of water,
and the majority of these are not pathogenic. Bacteria can be categorized as
Gram negative and Gram positive.
A selection of waterborne bacterial pathogens, as identified by the
WHO, is summarized in Table 2.2 . We will concentrate our more detailed
descriptions of each pathogen on those transmitted by ingestion of water
as opposed to inhalation or skin contact. Where available, information
is presented regarding the disease caused by each of these pathogens in
terms of symptoms, prevalence and treatment. Additionally, information is
given on the number of different species of each pathogen, their size and
appearance, with the reader being referred to original scientific articles
for more in-depth information on aspects such as cell biology, pathogen
life cycle, etc.
2.2.1. Campylobacter
There are several species of this type of bacteria. Campylobacter jejuni is the
one most commonly isolated from infected patients, although Campylobacter
coli , Campylobacter laridis and Campylobacter fetus have also all been found.
These bacteria are microaerophilic (require reduced oxygen) and capno-
philic (require increased carbon dioxide). They are Gram negative curved
spiral rods with a single unsheathed polar flagellum.