Dengue Fever : Clinical Presentation, Pathogenesis, Diagnostic Methods, Treatment & Management
Dengue fever is the most common and important arthropod borne
viral disease in human that is transmitted by the mosquitoes of genesis. two
species of ed's mosquitoes have been identified as vectors of dengue virus
beads,egypt and ed's alphabetics. these mosquitoes are widely distributed in
tropical and subtropical areas and most recently,in more temperate areas.
dengue is a serious disease,which affects more than one
hundred twenty countries in the world in twenty nineteen.it is named as one of
the top ten threats to human health by the world health organization. disease
spectrum can range from a mild flu like illness,which is usually seen in
classic dengue fever to a severe ,life threatening disease called severe
dengue, which is previously known as dengue hemorrhagic fever.
And it is characterized by coagulopathy increased vascular
fragility,and permeability has not closely monitored and managed hemorrhagic
fever is more likely to progress into a state of hypovolemic show. which is
known as dengue shock syndrome,or d s s. dengue virus belongs to the group of
flavour viruses,which contain a single stranded,non segmented rna
molecules,genetic material.there are four zero types of dengue virus have been
identified.
And several zero types can be in circulation during an
epidemic infection with one zero type gives a lifelong immunity against that
particular zero type.however,secondary infection with another zero. can cause
severe dengue and dengue shock syndrome within the same person.ultimately an
individual could be infected by all four zero types of virus. first,let's see. what
are the signs and symptoms of a dengue infection incubation period of the virus
is about four to ten days on average,following onset.
Symptoms usually last for about two to seven days,many
patients with dengue virus infection are asymptomatic. approximately one in
four people with dengue infection become symptomatic. symptomatic infection
commonly presents as a mile to moderate,non specific acute february
illness,about one in twenty patients with symptomatic disease develop severe
dengue.
Most of the time, these patients have a history of a prior
dengue infection. there are three phases of the clinical course of a dengue
viral infection. february phase. critical phase and convalescent or recovery
phase.let's discuss about them in detail in the following sections. first,let's
discuss about the february phase.high grade fever is the predominant symptom in
this period.in addition,patient may complain of severe headaches, along with
retro orbital.
Severe arthritis or joint pains,severe mild geez or muscle
pain,bone pain and some people may present with a macula,or macula,popular
rash. predominantly seen on flexed services. in addition,patient may present
with nausea and vomiting and mild hemorrhagic manifestations like pitti ki
purpura,bleeding gums. episodes or bleeding from nose, hematuria or blood and
urine. and attorney case test is positive in most patients. let's see what is
attorney test in the next slide.
The tourniquet test is performed by inflating a blood
pressure cuff around the upper arm to a midway between systolic and diastolic
blood pressure for five minutes after removing the cut. the number of petit key
per square inch is calculated that it is more than twenty than it is a positive
turn. a gay test,in addition to above signs and symptoms, patient may have
anorexia.
Or loss of appetite,sore throat,altered taste,sensation and
limb,fat and apathy as patient reaches the late days of february,face fever starts
to drop. this is known as death,or vessels,and it is due to the cessation of
the remedia.however,some patients may show some warning signs of progression
into severe dengue around the time of death.
Now let's see,what are those warning signs?as i told
before,these signs begin to appear around the time of death or vessels.these
include persistent vomiting. severe abdominal pain,fluid accumulation in spaces
like plural and paratonia,cavity mucus or bleeding,difficulty in
breathing,restlessness mhm. postural hypotension happen immediately,and
progressive increase in humanitarian due to him a concentration.the clinicians
should always monitor the patience with dengue for these warning signs.
And must provide,with appropriate supportive care to reduce
the risk of developing hypothermic shock. now let's come to the critical
phase.it begins after depressants and usually lasts for about twenty four to
forty eight hours,most patients clinically improved during this period. however,some
patients with a considerable plasma leakage can develop severe dengue within a
few hours during this phase.and in these patience,fever starts to reappear. this
pattern of fever is known as saddleback fever,or by basic fever.this graph
shows the reappearance of fever during the critical phase increased vascular
permeability is the cause of extensive plasma leakage in these patients.
Due to the plasma leakage,blood volume starts to drop,which
ultimately results in hypo olympic shock due to the plasma leakage,patient may
have conditions like plural effusion. and s i t s and due to the reduced blood
volume,patient may have hypotension,tactical cardia to kidney,reduced level of
consciousness.and him,a. in addition,these patients will show severe
hemorrhagic manifestations,including hematomas,or vomiting of blood,g eye
bleeding.
And hematuria,which also reduced the blood volume and
ultimately result in shock,some uncommon manifestations of severe dengue during
this phase include hepatitis. mio carditis,pancreatitis.and in satellite's. during
the convalescent or recovery phase,blood volume tends to stabilize by
reabsorbing extra vacated fluid into the bloodstream.hemodynamics status
stabilizes. h.y.m.medical stabilizes or may fall in some patients due to the
dialogue of reabsorbed fluid.white blood cell count starts to rise,as well as
the platelet count.
Now let's discuss about the pathogenesis of dengue
infection.it starts when an infected female leads mosquito bites a person for a
blood male. during mosquito feeding,the virus is inoculated into the
blood.female leads,mosquito requires blood for their egg maturation.unlike
other mosquitoes,they are daytime feature. they usually bite on the back of the
neck and ankle area primary reservoir of the virus as human when an infected
person is bitten by a non infected ed's mosquito.the virus is transmitted into
mosquito.
transmission.patients who are hospitalized for suspected
dengue infection. are advised to stay within bed nets to avoid transmission
during an outbreak,because an individual with dengue infection can transmit the
disease for about four to five days.a. cell and tissue trophism of the virus
plays a major role in pathogenesis of dengue infection.three major organ
systems are affected by the virus.the immune system.
Liver and the endothelial lining of blood vessels during a
mosquito bite virus enters through the skin and infects him.mature dendritic
cells,which are located in the skin.and the. then these infected dendritic
cells will reach the lymph nodes at the lymph nodes.monocytes and macrophages
recruit to halt the infection.however,these cells also get infected by the
virus. when these cells become infected,they secrete large amounts of cytokines
into the bloodstream,which mediate the early nonspecific symptoms of the
infection.
Not only that,when the monocytes and macrophages get
infected,they are unable to hold viral replication.and this will result in
increased viral load,while the host monocytes and macrophages undergo death by
appetites. increased viral load will result in dissemination of the virus via
bloodstream and reach the vital organs,including bone marrow and the liver.direct
destructive action of the virus on bone marrow,precursor cells,will cause drump
acid opinion.
and look,opinion,and due to the cellular destruction,patient
gets a severe bone pain.and because of its severity,this pain is also called
break bone pain.hypnotized damage will give rise to elevated transaminases in
blood. and due to anti thereal cell damage and thrombus it opinion patient will
have minor hemorrhagic manifestations.we discussed. as we discussed
before,secondary infection with another serotype will give rise to a more
severe clinical presentation than the primary infection.immunology behind this
condition is not well understood.in the. currently accepted theory as as
follows,almost all the patients with severe dengue have a previous history of
dengue infection with one or more zero types during a secondary infection.
T cells produce small amounts of non neutralizing
antibodies,which are directed to the surface proteins of dengue virus.when
these antibodies bind to the surface proteins,macro phages and monocytes. get
attached to the fc portion of the antibodies in order to neutralize the virus
and halt the infection.however,as the serotype is different from the previous
infection,macrophages and monocytes are unable to hold the infection. instead,they
formatted in antibody complexes,and the virus continues to proliferate
unchecked.this will result in the production of large amounts of cytokines and
complement system activation and which are the main causes of extensive
vascular effects in severe dengue?and this whole process is called antibody
dependent enhancement.also,the nonstructural protein one.
Or n s one antigen of the virus can directly activate the
complement system,which also contributes to the vascular effects. Early
detection of dengue infection is extremely important to prevent the patient
from developing hypothermic shock,therefore dengue should be suspected in a
patient with compatible signs and symptoms.in. who lives or travel to a dengue
endemic area,recently,patients with dengue infection typically present with
acute onset of fever,headache,body aches a nd sometimes rash.
Nucleic acid amplification tests are the preferred method of
diagnosis.real time reverse transcript as polymers.chain reaction is the
technique used to detect viral genomic material in this method. it has to be
done within the first week of symptom onset because with cessation of
berrima,the virus will no longer available in the bloodstream. detection of
viral n s one antigen by immunoassays,is another reliable method of
diagnosis.and it also has to be done within the first week of illness,even
though the n s one antigen presence within blood for about twelve days after
symptom.
onset,in addition,serologic tests can detect the antibodies
produced against a virus.i g m antibodies against a virus present in the blood
from four days after symptom onset. for the patients who present within the
first week after symptom onset,both i g m and n s one or nucleic acid
amplification test should be done for the patients who present more than after
a week of symptom onset.
I g m tests should be done,however serologic tests may give
false positive results due to their cross reactivity between other flavour
viruses like zika virus and japanese and safaris. Clinicians should be able to
rule out those other causes of the same clinical presentation and come to a
precise diagnosis testing for igg antibodies is not useful in diagnosing a
present infectious. Because they present during life after a dengue infection
enzyme linked to muno,sorbent assay,or alisa is the technique used to detect
antibodies against dengue virus.
Some common laboratory findings of dengue infection include
the following trump acid opinion,lucca pina,and mild to moderate increase in
serum transaminases. and severe infection patient may have increased him
adequate hypo protonema prolonged p t and a p t t and decreased for british
levels. finally,let's come to the treatment of dengue fever.unfortunately,there
is no specific anti viral drug available to treat this disease.supportive care
is advised to reduce signs and symptoms.
Patients are advised to stay well hydrated to prevent
dehydration caused by vomiting and high fever,aspirin and other types of non
steroidal anti-inflammatory drugs like ibuprofen. should not be used to reduce
fever because they have anticoagulin properties to control fever. a settlement
off a named tepid sponging or indicated and patients should be advised to avoid
mosquito bites to prevent transmission.
For severe dengue,closed monitoring and observation is required to prevent the patient from developing hypothermic shock for dehydration. iv fluid administration may be required. for patients with coagulopathy,fresh,frozen plasma is given,prophylactic platelet infusion is not beneficial. in these patients,can cause fluid,overloaded. See you again Thank you.
