Hello everybody my name is Zohir Chowdhury, and today's topic is about global burden of
vector-borne zoonotic diseases this is very important for us to understand some of these
very important terms so endemic refers to the constant presence and/or usual prevalence of
a disease or infectious agent in a population within a geographic area an infection is set to
be endemic in a population when that infection is maintained a steady state in a population without
the need for external input this is also the based on level of the disease this level is not
necessarily the desired level which may in fact be zero but rather is the observed level in the
absence of intervention and assuming that the level is not high enough to deplete the pool of
susceptible persons the disease may continue to occur at this level indefinitely thus the
base-10 level is often regarded as that expected level of the disease and in here we are seeing a
region where one disease is endemic occasionally the amount of disease in a community rises above
the expected level of expert epidemic refers to an to an increase often sudden in the number
of cases of a disease above what is normal it's normal expected in that population in that area
outbreak carries the same definition of epidemic but is often used for a more limited geographic
area pandemic on the other hand refers to an epidemic that has spread over several countries
or continents usually affecting a large number of population in here you can see a disease that
is quite high number seasonal but this is endemic because you're not seeing any sharp rises whereas
in here you have a disease that is much in lower number that is in steady state on the bottom but
you have an epidemic in here a rise in number of cases and then another rise in number of case in
here so the first epidemic and then the epidemic the major vector-borne diseases together account
for around 17% of all infectious diseases around the globe the burden of these diseases
is highest in tropical and subtropical areas and they disproportionately affect the poorest
population in the world as shown in this global map mosquito-borne diseases such as dengue malaria
chikungunya yellow fever and Zika by far take a very large toll on humans as seen in the table
below especially malaria takes approximately 1 million people's lives every year on the other
hand are bricks of new diseases such as SARS in 2002 swine flu in 2009 ebola in 2014 MERS between
2012 and 15 and Zika in 2000 2015 have claimed lives and overwhelmed health systems in many
many countries in this graph you can see temporal patterns of reported cases for selected introduced
vector borne diseases shown in red an endemic or long-established diseases shown in blue introduce
pathogens can cause can cause notable epidemics as seen in the u.s. from West Nile virus as well
as in India in due to chikungunya virus in here in 1999 the New York City Department of Health
reported a cluster of patients with Menninger encephalitis associated with muscle weakness
epidemiological evidence suggested that Ann Arbor virus was a probable cause clinicians
and veteran veterinarians collaborated to identify their agents as West Nile virus but
unfortunately identification and initial control efforts did not prevent the virus spreading from
east to west coast of North America within only 4 years causing national epidemics in 2002 and
and three similarly in the Indian Ocean island of réunion in 2005 hundreds of patients had painful
and disabling Polly etre a portal Jia and a subset presented with neurological science or fulminant
hepatitis a second wave of such symptoms in 2006 exceeded all expectations eventually affecting
more than 1/3 of the entire population of close to a 1 million people the causative agent was
identified as chikungunya virus which is also causing continuing epidemics in India with
several million cases so far other introduction of vector borne diseases have cost smaller outbreaks
but have been important in the expansion of the range of human populations at risk for example
dengue virus has spread to Hawaii Zika virus to the Micronesian island of Yap and she can
cunha virus to Europe whether the outbreak of chikungunya in Europe died out naturally
because of the arrival of the temperate autumn or was interrupted by mosquito control efforts
is still unclear a key challenge arises when the non specificity and similarity of symptoms caused
by many of these viruses especially Zika virus dengue and chikungunya virus that all present
with acute fever similar to many diseases endemic in the tropics such as malaria in here we can see
the transmission map of malaria and as you can see most of the transmission is within the tropical
areas and a lot of them is in sub-saharan Africa and South in South and South Asia here is a drink
dengue transmission maps again very similar is within the tropical areas between the tropical
areas of Central America sub-saharan Africa and South Asia in in the u.s. southern Texas and
southeastern states are a theoretical risk for transmission of dengue and sporadic outbreaks
the virus may be imported into the United States by travelers who are turning for endemic tropical
areas and that's how we have seen some cases of dengue viral disease in the US on the other hand
Western virus in the US as I mentioned earlier has been spreading since 1999 and going all the
way up until 2006 as you can see the cases has been spreading all over the United States and
in multiple and in multiple states here you can see the introduction and then within a few years
it becomes a huge epidemic there has been lasting since present on the other hand Zika transmission
it's another new disease and you can see in here that in 2018 there's been as well since were six
in have been a huge scare and better than 18 has been spreading in many many countries around the
globe on the other hand Lyme disease it's mostly isolated in north eastern US each dot in here
represent one case of Lyme disease and is placed randomly in the patients country of residence the
presence of a dot in a state does not necessarily mean that Lyme disease was acquired in that state
because people do travel between states and the place of residence is sometimes different from
the place where the patient's become infected by Lyme disease but you can definitely see that
the predominant places where Lyme disease is present is in the Northeast us on the other
hand plague also is a very important disease affecting many many countries including the
u.s. mostly Western us in the western US they're beans quite a few cases human cases but most of
the cases that we see in the in the u.s. are in the in the wildlife Ebola virus is another very
new disease that have been outbreak in recently especially in Africa and the Democratic Democratic
Republic of Congo as well as in western Africa of Guinea Sierra Leone and Liberia
in this figure we are saying rabies among wildlife in the United States by year and species from 1966
to 2014 the map on the other hand is showing major rabies virus variants among wildlife in the United
States and Puerto Rico from 2008 to 2015 black diagonal lines represent fox rabies variants
such as the Arizona gray fox and Texas gray fox quick concept checks true and false in the United
States southern Texas and southeastern states are a theoretical risk for transmission of dengue and
sporadic outbreaks true true and false multiple cases of Lyme disease as well as West Nile virus
have been confirmed in the United States true between 1976 and 2018 the largest outbreak of
Ebola was in Asia false it was in Africa in the US which of the falling wild animal has not been
diagnosed of rabies deed all of these animals have been diagnosed with rabies that's all thank you