Estimating the global burden of foodborne disease by kcx20576



                                                   Estimating the global burden of foodborne disease
                    For more on FERG see http://   Later this spring, WHO will publish the   Pharmaceuticals, formerly Ministry of           The Enteric Diseases Taskforce has a
                  annual report of the Foodborne Disease    Health, Amman, Jordan), Chair of the          priority listing of 21 enteric pathogens
                                                   Burden Epidemiology Reference Group       FERG parasitic diseases taskforce.            for early review. “Foodborne diseases
                      For more on FERG’s second
                                                   (FERG), summarising the outcome of          FERG’s three current thematic               such as cholera, dysentery, brucellosis,
                      annual meeting see http://   the second FERG meeting held Nov          taskforces are now doing thorough             and typhoid are major concerns due
                  17–21, 2008, in Geneva, Switzerland.      reviews to assess the burden of different      to their severity and their impact on
                                                   Declared a “resounding success”, the      diseases that may be transmitted by           developing countries”, commented
                                                   event brought together world experts      food, evaluating what proportion              Martyn Kirk, Senior Epidemiologist
                    For more on surveillance of
               foodborne diseases in Australia     and stakeholders committed to the         of each disease is foodborne. Tools           of OzFoodNet (Canberra, Australia)—
                 see     WHO initiative to provide reliable        are also being developed to enable            Australia’s national system of sur-
                                                   and accurate estimates of the global      individual countries to accurately assess     veillance of foodborne diseases—and
                   For more on surveillance of
                                                   burden caused by all foodborne            their own burden of foodborne disease.        Chair of the FERG enteric diseases
               foodborne disease in the US see
               diseases. “The FERG initiative is now     Some developed countries have done            taskforce. Others, such as non-typhoidal
                                                   looking forward to another year of        assessments showing that the burden           salmonellosis, campylobacteriosis, and
                                                   fruitful collaboration between the        of foodborne illness is considerable,         norovirus infections, are also important
                                                   many experts in this field and we          but most lack data on problems caused         causes of illness in developed countries.
                                                   anticipate the launch of the new          by chemicals or parasites. “These             “In many cases these pathogens cause
                                                   country studies taskforce later in        studies estimate incidence of illness         mild, self-limiting illness but the sheer
                                                   2009”, commented Claudia Stein who        but do not use burden of disease              number of cases of enteric disease
                                                   leads the initiative at WHO (Geneva,      methodologies using standard metrics,         makes the social and economic costs
                                                   Switzerland) .                            such as disability-adjusted life years        significant”, said Kirk. He stresses that
                                                     Arie Havelaar (RIVM, Bilthoven, and     (DALY). These metrics are needed to           clearer statements and appropriate
                                                   Utrecht University, Netherlands), Chair   compare the burden of diseases with           priorities will only be possible once
                                                   of FERG, regards the aims of the group    different severities and mortality rates”,     the FERG has completed its work
                                                   as “ambitious” but says that every        explained Havelaar.                           and looked at all enteric diseases
                                                   effort will be made to meet the target       Jorgen Schlundt, Director of the            comprehensively, predicting that “we
                                                   of estimating the global burden of        Department of Safety, Zoonoses and            may see some surprising results from
                                                   foodborne illness caused by chemicals,    Foodborne Diseases at WHO points              the country studies”.
                                                   parasites, and enteric infections by      out that the FERG initiative will               Gargouri says that the mildness of
                                                   2012. “Where possible, this includes      provide an important baseline against         many foodborne diseases is, in her
                                                   estimating the disease burden that is     which to compare future changes in            experience, one of the major factors
                                                   attributable to specific commodities,      foodborne disease incidence. “We              that makes accurate surveillance
                                                   such as meats of animal origin, fish,      know that the problem of foodborne            difficult, and under-reporting con-
                                                   fresh produce, and so on”, he said.       disease has increased during the past         siderable. “Cases of diarrhoea, for
                                                   “This is a particular challenge for       few decades, but measuring the rate           example, that do not require medical
                                                   pathogens commonly spread by food         of future decreases as a function of          attention are generally not detected
                                                   but that are also transmitted by water,   efficient interventions is impossible           by the health-care system”, she said.
                                                   animals, or through person to person      without this all-important baseline—          One of the major projects of the enteric
                                                   contact”, added Neyla Gargouri (Hakim     which means we really will not know           diseases taskforce is a systematic review
                                                                                             which interventions succeed and               of the incidence and mortality due
                                                                                             which fail”, he told TLID. This will be a     to diarrhoeal diseases in people over
                                                                                             particularly important part of the work       5 years old. “Led by Robert Black (Johns
                                                                                             of the chemical and toxins taskforce,         Hopkins University, Baltimore, USA),
                                                                                             since very little data on the global          this review is gathering data on the
                                                                                             burden of illness caused by chemical          incidence and specific microbiological
                                                                                             contamination of food exist anywhere          causes of diarrhoeal disease to allow
                                                                                             in the world, despite well-publicised         attribution of diarrhoea to different
                                                                                             occurrences that are “the tip of the          pathogens in the priority list”,
                                                                                             iceberg” according to Herman Gibb             explained Kirk. He points out that this
AP/PA Photos

                                                                                             (Tetra Tech Sciences, Washington DC,          review is different from many others
                                                                                             USA, formerly of the Environmental            already published since it focuses
               A food market in Beijing, China                                               Protection Agency).                           on diarrhoeal diseases affecting age

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groups other than small children. At              of the morbidity, mortality, and             protocols”, said Stein. Pilot studies will
the recent meeting of FERG, the enteric           disability, by age and sex of all these      be completed in a range of different
diseases taskforce recommended                    parasitic diseases for all regions of the    countries, in order to develop selection
that WHO commission further work                  world, discovering what proportion           criteria for suitable country sites
to examine the global incidence of                is foodborne. By the end of the first         and identify the sites of the key pilot
invasive foodborne illnesses, brucellosis         5 years, interactive maps will be created    projects. “Strengthening the capacity
and listeriosis, along with toxin-based           using geographic information system          to monitor foodborne diseases at a
illness, such as food poisoning due to            (GIS)-type technologies to show the          country level is a key aim of FERG and
Clostridium botulinum, C perfingens, and           available literature and the distribution    will contribute to the initial estimates
Staphylococcus aureus.                            by country, along with the potential         of foodborne disease burden obtained
   The parasitic diseases taskforce has           sources of infection where applicable.       by 2012”, said Stein. Beyond that, an
identified several major foodborne                 “Mapping the parasitic diseases data         online global foodborne diseases atlas
parasites worthy of study, including              will contribute to identifying the gaps      will provide morbidity, disability, and
Entamoeba         histolytica,     Giardia        in the literature and ultimately to          mortality data to a wide audience,
intestinalis, Toxoplasma gondii, Fasciola         advising WHO on research priorities at       including scientists in the developing
spp, Echinococcus spp, and Taenia solium.         the country level”, said Gargouri.           world. “Our main goal is to eventually
“The prioritisation criteria included the           The country studies taskforce that         enable countries to monitor their
severity and magnitude of the parasitic           will be launched later this year will        own disease burden for the purpose
disease, its geographical distribution,           do the groundwork that will lead to          of informing policy makers and
the propensity of the parasite to                 the development of new methods to            assisting them in the evaluation and
cause point-source outbreaks, and the             consistently monitor the burden of           development of food safety standards
availability of existing data”, explained         foodborne disease at an individual           and policies”, she concluded.
Gargouri. In the next 3 years, the                country level. “One of the major
parasitic diseases taskforce intends              objectives will be to provide countries      Kathryn Senior
to conduct epidemiological reviews                with relevant and validated tools and

Substantial progress made in malaria research, say experts
Two phase II studies in Tanzania and              alongside routine vaccinations”, says        promising work, we need to continue           For more on the RTS,S/AS
Kenya make “a strong case” for moving             David Schellenberg of LSHTM, and             other research efforts, including those        malaria vaccine studies see
                                                                                                                                             N Engl J Med 2008; 359: 2521–32,
forward to phase III trials of the most           their efficacy was not compromised.            on treatments“, says Drakeley.                2533–44, 2599; DOI:10.1056/
advanced malaria vaccine candidate,               The WHO Expanded Program on                    In the first trial of its kind to evaluate   NEJMoa0807381, DOI:10.1056/
GlaxoSmithKline Biologicals’ RTS,S/AS,            Immunization could therefore provide         the use of artemisinin combination            NEJMoa0807773, DOI:10.1056/
say researchers. This broader evaluation          an optimal delivery platform. Drakeley,      therapy (ACT) in 253 pregnant women,
                                                                                                                                             For more on malaria treatment
is now essential to ascertain long-term           who was part of the LSHTM team that          published in December, the current            in pregnancy see PloS Medicine
efficacy, says Chris Drakeley (London               collaborated with Tanzanian researchers      standard six-dose ACT used in Thailand        2008; 5: e253; DOI:10.1371/
School of Hygiene and Tropical Medicine           on the infant study, suggests that           (artemether-lumefantrine) was found           journal.pmed.0050253
[LSHTM], UK). However, continued                  proposed phase III studies are likely to     to be safe to use to treat pregnant
development of new medications and                take about 5 years to complete. If these     women. However its efficacy was
vector control, needs to maintained.              studies are successful, the licensing        inferior to the 7-day artesunate mono-
“We have several approaches to malaria            application will take a further 2–3 years.   therapy because drug concentrations
control“, he says, “but we need to                   Although both studies found               were reduced during pregnancy.
know which combinations of available              strong immune responses, a previous          Neither course of treatment achieved
options are most cost effective, in the            version of the vaccine, with a different      the 95% cure rate recommended by
different malaria regions“.                        adjuvant, found that protection in           WHO. The researchers conclude that
   The studies, coordinated by the PATH           adults required a booster dose beyond        a higher-dose ACT regimen should
Malaria Vaccine Initiative (MVI), show            6 months, and that protection in             now be evaluated for the treatment of
that RTS,S/AS reduced malaria episodes            children was around 30–40%, Drakeley         pregnant women with uncomplicated
by 53% in children aged 5–17 months,              explains. “The results of these latest       falciparum malaria. These findings
and in 65% of infants (aged less than             trials are very encouraging, but we still    have sparked “renewed optimism over
12 months), with a favourable safety              need more data on how this vaccine is        eradication of malaria”, says Drakeley.
profile. The latter study was “the                 working and how this new adjuvant
first time the vaccine has been given              has enhanced its effect. Despite this         Kelly Morris Vol 9 February 2009                                                                                                                          81

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