Angeles University Foundation College of Allied Medical
ProfessionsMedical Technology Department
Dengue and Dengue Hemorrhagic Fever
Submitted by:Gamboa, Lois Danielle L.Paule, Diosshane V.Cruz,
Steffy Mae W.Banjal, Ryan Ali Y.Castro, Ronelyn Joy C.Submitted
to:Mendoza, Regina Carmela S.Dr. Estelita D. Cayabyab
Contents
Origin and History of Dengue and DHF (Paule)Causative Organism
(Cruz)Factors Contributing to the Re-emergence of DHF
(Banjal)Transmission (Castro)Symptoms (Castro)Laboratory Diagnosis
(Gamboa)Treatment (Mendoza)Prevention and Control (Gamboa)
Origin and History (Diosshane Paule)The origins of the word
dengue are not clear, but one theory is that it is derived from the
Swahili phrase "Ka-dinga pepo", meaning "cramp-like seizure caused
by an evil spirit". The Swahili word "dinga" may possibly have its
origin in the Spanish word "dengue" meaning fastidious or careful,
which would describe the gait of a person suffering the bone pain
of dengue fever. Alternatively, the use of the Spanish word may
derive from the similar-sounding Swahili. Slaves in the West Indies
who contracted dengue were said to have the posture and gait of a
dandy, and the disease was known as "Dandy Fever".The first record
of a case of probable dengue fever is in a Chinese medical
encyclopedia from the Jin Dynasty (265420 AD) which referred to a
water poison associated with flying insects. The first recognized
Dengueepidemicsoccurred almost simultaneously in Asia, Africa, and
North America in the 1780s, shortly after the identification and
naming of the disease in 1779. The first confirmed case report
dates from 1789 and is by Benjamin Rush, who coined the
term"breakbone fever"because of the symptoms of myalgia and
arthralgia.Dengue fever is a disease caused by a family of viruses
that are transmitted by mosquitoes. It is an acute illness of
sudden onset that usually follows a benign course with symptoms
such as headache, fever, exhaustion, severe muscle and joint pain,
swollen glands (lymphadenopathy), and rash. The presence (the
"dengue triad") of fever, rash, and headache (and other pains) is
particularly characteristic of dengue. Other signs of dengue fever
include bleeding gums, severe pain behind the eyes, and red palms
and soles.Dengue can affect anyone but tends to be more severe in
people with compromised immune systems. Because it is caused by one
of four serotypes of virus, it is possible to get dengue fever
multiple times. However, an attack of dengue produces immunity for
a lifetime to that particular serotype to which the patient was
exposed.Severe dengue (previously known as Dengue Hemorrhagic
Fever) was first recognized in the 1950s during dengue epidemics in
the Philippines and Thailand. Today, severe dengue affects most
Asian and Latin American countries and has become a leading cause
of hospitalization and death among children in these regions.
Dengue hemorrhagic fever is a more severe form of the viral
illness. Symptoms include headache, fever, rash, and evidence of
hemorrhage in the body. Petechiae (small red or purple splotches or
blisters under the skin), bleeding in the nose or gums, black
stools, or easy bruising are all possible signs of hemorrhage. This
form of dengue fever can be life-threatening and can progress to
the most severe form of the illness, dengue shock syndromeThe viral
etiology and thetransmissionby mosquitoes were only deciphered in
the 20th century. The socioeconomic impact of World War II resulted
in increased spread globally. Nowadays, about 2.5 billion people,
or 40% of the worlds population, live in areas where there is a
risk of dengue transmission. Dengue spread to more than 100
countries in Asia, the Pacific, the Americas, Africa, and the
Caribbean.Dengue is a mosquito-borne infection found in tropical
and sub-tropical regions around the world. In recent years,
transmission has increased predominantly in urban and semi-urban
areas and has become a major international public health concern.
Outbreaks have occurred recently in the Caribbean, including Puerto
Rico, the U.S. Virgin Islands, Cuba, and Central America. Cases
have also been imported via tourists returning from areas with
widespread dengue, including Tahiti, Singapore, the South Pacific,
Southeast Asia, the West Indies, India, and the Middle East
(similar in distribution to the areas of the world that harbor
malaria and yellow fever). Dengue is now the leading cause of acute
febrile illness in U.S. travelers returning from the Caribbean,
South America, and Asia.In 2011, Bolivia, Brazil, Columbia, Costa
Rica, El Salvador, Honduras, Mexico, Peru, Puerto Rico, and
Venezuela reported a large number of dengue cases. Paraguay
reported a dengue fever outbreak in 2011, the worst since 2007.
Hospitals were overcrowded, and patients had elective surgeries
canceled due to the outbreak.Dengue fever is common, in at least
100 countries in Asia, the Pacific, the Americas, Africa, and the
Caribbean. Thailand, Vietnam, Singapore, and Malaysia have all
reported an increase in cases.According to the CDC, there are an
estimated 100 million cases of dengue fever with several hundred
thousand cases of dengue hemorrhagic fever requiring
hospitalization each year. Nearly 40% of the world's population
lives in an area endemic with dengue. The World Health Organization
(WHO) estimates that 22,000 deaths occur yearly, mostly among
children.
Causative Organism (Steffy Cruz)Dengue Fever (DF) is a viral
infectious disease transmitted by mosquito (AEDES) bite. The virus
attack blood cell, liver, and spleen and leads to low white blood
cell and decreases platelets (Blood Clotting component). There are
four distinct, but closely related, serotypes of the virus that
cause dengue (DEN-1, DEN-2, DEN-3 and DEN-4). Recovery from
infection by one provides lifelong immunity against that particular
serotype. However, cross-immunity to the other serotypes after
recovery is only partial and temporary. Subsequent infections by
other serotypes increase the risk of developing severe dengue.The
Aedes aegypti mosquito is the primary vector of dengue. The virus
is transmitted to humans through the bites of infected female
mosquitoes. After virus incubation for 410 days, an infected
mosquito is capable of transmitting the virus for the rest of its
life.Infected humans are the main carriers and multipliers of the
virus, serving as a source of the virus for uninfected mosquitoes.
Patients who are already infected with the dengue virus can
transmit the infection (for 45 days; maximum 12) via Aedes
mosquitoes after their first symptoms appear.The Aedes aegypti
mosquito lives in urban habitats and breeds mostly in man-made
containers. Unlike other mosquitoes Ae. aegypti is a daytime
feeder; its peak biting periods are early in the morning and in the
evening before dusk. FemaleAe. aegypti bites multiple people during
each feeding period.Aedes albopictus, a secondary dengue vector in
Asia, has spread to North America and Europe largely due to the
international trade in used tires (a breeding habitat) and other
goods (e.g. lucky bamboo). Ae. albopictus is highly adaptive and
therefore can survive in cooler temperate regions of Europe. Its
spread is due to its tolerance to temperatures below freezing,
hibernation, and ability to shelter in microhabitats.
Factors Contributing to the Re-emergence of DHF (Ryan Banjal)The
disease pattern associated with dengue-like illness from 1780 to
1940 was characterized by relatively infrequent but often large
epidemics. However, it is likely that dengue viruses became endemic
in many tropical urban centers during this time because during
inter-epidemic periods, when there was no apparent disease
transmission, non-immune visitors invariably contracted a
dengue-like illness within months of their arrival.The ecologic
disruption in the Southeast Asia and Pacific theaters during and
following World War II created ideal conditions for increased
transmission of mosquito-borne diseases, and it was in this setting
that a global pandemic of dengue began. With increased epidemic
transmission, hyperendemicity (the cocirculation of multiple dengue
virus serotypes) developed in Southeast Asian cities and epidemic
dengue hemorrhagic fever (DHF), a newly described disease, emerged.
The first known epidemic of DHF occurred in Manila, Philippines, in
1953 to 1954, but within 20 years the disease in epidemic form had
spread throughout Southeast Asia; by the mid-1970s, DHF had become
a leading cause of hospitalization and death among children in the
region. In the 1970s, dengue was reintroduced to the Pacific
Islands and epidemic activity increased there and in the Americas.
During the 1980s and 1990s, epidemic dengue transmission
intensified, and there is now a global resurgence of dengue fever,
with expanding geographic distribution of both the mosquito vectors
and the viruses, increased incidence of disease caused by an
increased frequency of epidemic transmission, and the emergence of
DHF in many new countries.In Asia, epidemic DHF has expanded
geographically from Southeast Asian countries west to India, Sri
Lanka, the Maldives, and Pakistan and east to China. Several island
countries of the South and Central Pacific (Niue, Palau, Yap, Cook
Islands, Tahiti, New Caledonia, and Vanuatu) have experienced major
or minor DHF epidemics. Epidemiologic changes in the Americas,
however, have been the most dramatic. In the 1950s, 1960s, and most
of the 1970s, epidemic dengue was rare in the American region
because the principal mosquito vector, Aedes aegypti, had been
eradicated from most of Central and South America. The eradication
program was discontinued in the early 1970s, and this species then
began to reinvade the countries from which it had been eradicated.
By the 1990s, A. aegyptihad nearly regained the geographic
distribution it held before eradication was initiated. Epidemic
dengue invariably followed reinfestation of a country byA. aegypti.
By the 1980s, the American region was experiencing major epidemics
of dengue in countries that had been free of the disease for 35 to
130 years. New dengue virus strains and serotypes were introduced
(DEN-1 in 1977, a new strain of DEN-2 in 1981, DEN-4 in 1981, and a
new strain of DEN-3 in 1994). Moreover, many countries of the
region evolved from nonendemicity (no endemic disease) or
hypoendemicity (one serotype present) to hyperendemicity (multiple
serotypes present), and epidemic DHF emerged, much as it had in
Southeast Asia 25 years earlier. From 1981 to 1997, 24 American
countries reported laboratory-confirmed DHF.The factors responsible
for the dramatic resurgence and emergence of epidemic dengue and
DHF, respectively, as a global public health problem in the past 17
years are complex and not fully understood. However, the resurgence
appears to be closely associated with demographic and societal
changes over the past 50 years. Two major factors have been the
unprecedented global population growth and the associated unplanned
and uncontrolled urbanization, especially in tropical developing
countries. The substandard housing, crowding, and deterioration in
water, sewer, and waste management systems associated with
unplanned urbanization have created ideal conditions for increased
transmission of mosquito-borne diseases in tropical urban centers.A
third major factor has been the lack of effective mosquito control
in areas where dengue is endemic. The emphasis during the past 25
years has been on space spraying with insecticides to kill adult
mosquitoes; this has not been effective and, in fact, has been
detrimental to prevention and control efforts by giving citizens of
the community and government officials a false sense of security
(38). Additionally, the geographic distribution and population
densities of A. aegypti have increased, especially in urban areas
of the tropics, because of increased numbers of mosquito larval
habitats in the domestic environment. The latter include
nonbiodegradable plastics and used automobile tires, both of which
have increased dramatically in prevalence during this period.A
fourth factor responsible for the global emergence of dengue and
DHF is increased air travel, which provides the ideal mechanism for
the transport of dengue and other urban pathogens between
population centers of the world. For instance, in 1994, an
estimated 40 million persons departed the United States by air,
over 50% of who traveled for business or holiday to tropical
countries where dengue is endemic. Many travelers become infected
while visiting tropical areas but become ill only after returning
home, resulting in a constant movement of dengue viruses in
infected humans to all areas of the world and ensuring repeated
introductions of new dengue virus strains and serotypes into areas
where the mosquito vectors occur.A fifth factor that has
contributed to the resurgence of epidemic dengue has been the decay
in public health infrastructures in most countries in the past 30
years. Lack of resources has led to a critical shortage of trained
specialists who understand and can develop effective prevention and
control programs for vector-borne diseases. Coincident with this
has been a change in public health policy that placed emphasis on
emergency response to epidemics by using high-technology mosquito
control methods rather than on preventing those epidemics by using
larval source reduction through environmental hygiene, the only
method that has been shown to be effective.In summary, demographic
and societal changes, decreasing resources for vector-borne
infectious disease prevention and control, and changes in public
health policy have all contributed to increased epidemic dengue
activity, the development of hyperendemicity, and the emergence of
epidemic DHF. Tropical country Mosquitos are mostly in tropic
countries. No effective mosquito control efforts are underway in
most countries with dengue. Precautionary measures should always be
followed.- Application of mosquito repellant.- Removal of stagnant
water- Tires should be disposed properly Public health systems to
detect and control epidemics are deteriorating around the world.-
It is for reason that the community would be aware on how to
prevent dengue and to know whats happening. Rapid growth of cities
in tropical countries has led to overcrowding urban decay, and
substandard sanitation, allowing more mosquitoes to live closer to
more people. The increase in non-biodegradable plastic packaging
and discarded tires is creating new breeding sites for mosquitoes
Increased jet air travel is helping people infected with dengue
viruses to move easily from city to city.
Transmission (Ronelyn Castro)Dengue viruses are transmitted to
humans (host) through the bites of the female striped Aedes aegypti
mosquito (vector). This variety of mosquito breeds easily during
the rainy seasons. The dengue virus is transmitted to its host
during probing and blood feeding. The mosquito may carry the virus
from one host to another host and the mosquito is most active in
the early morning and later afternoon. Incubation period occurs
when the viruses has been transmitted to the human host. The period
ranges from 3 to 15 days before the characteristics of dengue
appear. During incubation time, the dengue viruses multiply.The
dengue virus is spread through a human-to-mosquito-to-human cycle
of transmission. Typically, four days after being bit by an
infected Aedes aegypti mosquito, a person will develop viremia, a
condition in which there is a high level of the dengue virus in the
blood. Viremia lasts for approximately five days, but can last as
long as twelve days. On the first day of viremia, the person
generally shows no symptoms of dengue. Five days after being bit by
the infected mosquito, the person develops symptoms of dengue
fever, which can last for a week or longer.
How does an Aedes aegypti mosquito become a dengue vector? After
a mosquito feeds on the blood of someone infected with the dengue
virus, that mosquito becomes a dengue vector. The mosquito must
take its blood meal during the period of viremia, when the infected
person has high levels of the dengue virus in the blood. Once the
virus enters the mosquito's system in the blood meal, the virus
spreads through the mosquito's body over a period of eight to
twelve days. After this period, the infected mosquito can transmit
the dengue virus to another person while feeding. Does a mosquito
infected with the dengue virus only transmit the virus to the next
person it feeds on? No, once infected with dengue, the mosquito
will remain infected with the virus for its entire life. Infected
mosquitoes can continue transmitting the dengue virus to healthy
people for the rest of their life spans, generally a three- to
four-week period.Both male and female mosquitoes feed on plant
nectars, fruit juices, and other plants sugars as their main energy
source. Why, then, do mosquitoes bite humans? Female mosquitoes
require blood to produce eggs, so they bite humans. Each female
mosquito can lay multiple batches of eggs during its lifetime, and
often Aedes aegypti take several blood meals before laying a batch
of eggs. When a female mosquito is infected with the dengue virus,
the virus is present in its salivary glands. How does the virus
travel from the mosquito's salivary glands into a human? When
taking a blood meal, an infected female mosquito injects its saliva
into the human host to prevent the host's blood from clotting and
to ease feeding. This injection of saliva infects the host with the
dengue virus.Are mosquito bites the only way the dengue virus can
be transmitted to humans? In rare events, dengue can be transmitted
during organ transplantations or blood transfusions from infected
donors. There is also evidence that an infected pregnant mother can
transmit the dengue virus to her fetus. Despite these rare events,
the majority of dengue infections are transmitted by mosquito
bites.Because of the approximately 7-day viremia in humans,
bloodborne transmission is possible through exposure to infected
blood, organs, or other tissues (such as bone marrow). In addition,
perinatal DENV transmission occurs, and the highest risk appears to
be among infants whose mothers are acutely ill around the time of
delivery. It is not known if DENV is transmitted through breast
milk.
Symptoms (Ronelyn Castro)The signs and symptoms of Dengue fever
are as follows:- High fever (104 F, 40C)- Chills- Headache- Red
eyes, pain in the eyes- Enlarged lymph nodes- Deep muscle and joint
pains (during first hours of illness)- Loss of appetite- Nausea and
vomiting- Low blood pressure and heart rate- Extreme
fatigueBasically, dengue commences with high fever and other signs
as listed above for 2 to 4 days. Then, the temperature drops
rapidly and intense sweating takes place. After about a day with
normal temperature and a feeling of well-being, the temperature
rises abruptly again. Rashes (small red bumps) show up on the arms,
legs and the entire body simultaneously along with fever. However,
rashes rarely occur on the face. The palms of the hands and soles
of the feet may be swollen and bright red. Although the patient may
feel exhausted for several weeks, most cases of dengue take
approximately one week to recover. Once a person recovers from
dengue, he or she will have antibodies in their bloodstream which
will prevent them from having a relapse for about a
year.Characteristics of the stages of Dengue Fever: Stage I: Acute
fever stage. (~Day 1-5). At this phase the patients have high fever
(39-40 degree Celsius) with aching, abdominal pain, nausea,
vomiting. Anti-pyritic such as paracetamol is important to lower
body temperature in order to provide the body minimizes fluid loss.
REHYDRATION by food and electrolyte fluid, will replace the fluid
in the circulation for the patients. If the patient, especially
children do not eat/drink enough and look weak, seek medical
attention urgently.
Stage II: Critical stage. (~Day 5-7), at this stage when the
body temperature drops, normally within 24 hours, the plasma (Fluid
part of blood component) leaks and the blood pressure will drop.
Patients will be restless, weak, have cold clammy skin, fast pulse,
in severe case with very low platelets they could vomit up blood,
have internal hemorrhage and die with circulatory failure or
respiratory failure due to internal bleeding/ fluid retention. It
is very important to provide appropriate intravenous fluid to the
patients in this stage to prevent poor blood perfusion to the vital
organ and not to overload the fluid in term of third space leakage
prevention.
Stage III: Recovery phase. It takes a couple days for the
patients to get back to normal. At this phase the patients will
gain back appetite (A), have slower pulse rate (Bradycardia=B),
have convalescent rash at legs and arms (C) and pass more water
(Diuresis=D). You may recognize these steps by A-B-C-D.
Stage 4: Shock and death (10% of all cases reach this stage)
Typical dengue is fatal in less than 1% of cases. The acute
phase of the illness with fever and myalgias lasts about one to two
weeks. Convalescence is accompanied by a feeling of weakness
(asthenia), and full recovery often takes several weeks.
Laboratory Diagnosis (Lois Gamboa)Clinicians should consider
dengue in a patient who was in an endemic area within 2 weeks
before symptom onset. All suspected cases should be reported to the
local health department, because dengue is a nationally reportable
disease. Laboratory confirmation can be made from a single
acute-phase serum specimen obtained early (5 days after fever
onset) in the illness by detecting DENV genomic sequences with
RT-PCR or DENV nonstructural protein 1 (NS1) antigen by
immunoassay. Later in the illness (4 days after fever onset), IgM
anti-DENV can be detected with ELISA. For patients presenting
during the first week after fever onset, diagnostic testing should
include a test for DENV (PCR or NS1) and IgM anti-DENV. For
patients presenting >1 week after fever onset, IgM anti-DENV is
most useful, although NS1 has been reported positive up to 12 days
after fever onset.Presence of DENV by PCR or NS1 antigen in a
single diagnostic specimen is considered laboratory confirmation in
patients with a compatible clinical and travel history. IgM
anti-DENV in a single serum sample suggests a probable, recent DENV
infection. IgM anti-DENV seroconversion in acute- and
convalescent-phase serum specimens is considered laboratory
confirmation of dengue.IgG anti-DENV by ELISA in a single serum
sample is not useful for diagnostic testing, because it remains
elevated for life after any DENV infection and can be falsely
positive in people with antibodies to other flaviviruses (such as
West Nile, yellow fever, Japanese encephalitis).Diagnosis of dengue
involves isolation of the virus through serological tests, or by
molecular methods. Diagnosis of acute or recent dengue infection
can be established by testing serum samples during the first 5 days
of symptoms and/or early convalescent phase.Tests may include:
Arterial blood gases Antibody titer for dengue virus types Complete
blood count (CBC) Polymerase chain reaction (PCR) test for dengue
virus types Coagulation studies Electrolytes Hematocrit Liver
enzymes Platelet count Serum studies from samples taken during
acute illness and convalescence (increase in titer to
Dengueantigen) Tourniquet test (causes petechiae to form below the
tourniquet) X-ray of the chest (may demonstrate pleural
effusion)
Laboratory diagnosis of dengue virus infection can be made by
the detection of specific virus, viral antigen, genomic sequence,
and/or antibodies. At present, the three basic methods used by most
laboratories for the diagnosis of dengue virus infection are viral
isolation and characterization, detection of the genomic sequence
by a nucleic acid amplification technology assay, and detection of
dengue virus-specific antibodies. After the onset of illness, the
virus is found in serum or plasma, circulating blood cells, and
selected tissues, especially those of the immune system, for
approximately 2 to 7 days, roughly corresponding to the period of
fever. Molecular diagnosis based on reverse transcription (RT)-PCR,
such as one-step or nested RT-PCR, nucleic acid sequence-based
amplification (NASBA), or real-time RT-PCR, has gradually replaced
the virus isolation method as the new standard for the detection of
dengue virus in acute-phase serum samples.Laboratory findings
commonly include leucopenia, thrombocytopenia, hyponatremia,
elevated aspartate aminotransferase and alanine aminotransferase,
and a normal erythrocyte sedimentation rate.Data are limited on
health outcomes of dengue in pregnancy and effects of maternal DENV
infection on the developing fetus. Perinatal DENV transmission can
occur, and peripartum maternal infection may increase the
likelihood of symptomatic disease in the newborn. Of the 34
perinatal transmission cases described in the literature, all
developed thrombocytopenia and all but 1 had fever in the first 2
weeks after birth. Nearly 40% had a hemorrhagic manifestation, and
one-fourth had hypotension. Transplacental transfer of maternal IgG
anti-DENV (from a previous maternal infection) may increase risk
for severe dengue among infants infected at 612 months of age.
Treatment (Regina Mendoza)There is no specific treatment for
dengue fever. No specific antiviral agents exist for dengue.
Patients should be advised to stay well hydrated and to avoid
aspirin (acetylsalicylic acid), aspirin-containing drugs, and other
non-steroidal anti-inflammatory drugs (such as ibuprofen) because
of their anticoagulant properties. Fever should be controlled with
acetaminophen and tepid sponge baths. Febrile patients should avoid
mosquito bites to reduce risk of further transmission. For those
who develop severe dengue, close observation and frequent
monitoring in an intensive care unit setting may be required.
Prophylactic platelet transfusions in dengue patients are not
beneficial and may contribute to fluid overload.For severe dengue,
medical care by physicians and nurses experienced with the effects
and progression of the disease can save lives decreasing mortality
rates from more than 20% to less than 1%. Maintenance of the
patient's body fluid volume is critical to severe dengue care. A
transfusion of fresh blood or platelets can correct bleeding
problems Intravenous (IV) fluids and electrolytes are also used to
correct electrolyte imbalances Aspirin and non-steroidal
anti-inflammatory drugs should only be taken under a doctor's
supervision because of the possibility of worsening bleeding
complications. Acetaminophen (Tylenol) and codeine may be given for
severe headache and for joint and muscle pain (myalgia). Oxygen
therapy may be needed to treat abnormally low blood oxygen
Rehydration with intravenous (IV) fluids is often necessary to
treat dehydration Supportive care in an intensive care
unit/environment
There is no vaccine to protect against dengue. Developing a
vaccine against dengue/severe dengue has been challenging although
there has been recent progress in vaccine development. The WHO
provides technical advice and guidance to countries and private
partners to support vaccine research and evaluation. Several
candidate vaccines are in various phases of trials.Note:
Researchers have found that the juice obtained from the papaya
leaves helps in the dengue fever treatment. The extract obtained
from the papaya leaf increases the platelet count also known as
thrombocytes in patients with dengue fever.
Prevention and Control (Lois Gamboa)At present, the only method
to control or prevent the transmission of dengue virus is to combat
vector mosquitoes through: Preventing mosquitoes from accessing
egg-laying habitats by environmental management and modification;
Disposing of solid waste properly and removing artificial man-made
habitats; Covering, emptying and cleaning of domestic water storage
containers on a weekly basis; Applying appropriate insecticides to
water storage outdoor containers; Using of personal household
protection such as window screens, long-sleeved clothes,
insecticide treated materials, coils and vaporizers; Improving
community participation and mobilization for sustained vector
control; Applying insecticides as space spraying during outbreaks
as one of the emergency vector control measures; Active monitoring
and surveillance of vectors should be carried out to determine
effectiveness of control interventions.
Since no vaccine is currently available, although several are in
clinical trials; no chemoprophylaxis is available to prevent
dengue. Travelers to dengue-endemic areas are at risk of getting
dengue; risk increases with longer duration of travel and disease
incidence in the travel destination (such as during dengue season
and during epidemics). Travelers should be advised to avoid
mosquito bites by taking the following preventive measures: Select
accommodations with well-screened windows and doors or air
conditioning when possible. Aedes mosquitoes typically live indoors
and are often found in dark, cool places, such as in closets, under
beds, behind curtains, and in bathrooms. Travelers should be
advised to use insecticides to get rid of mosquitoes in these
areas. Wear clothing that adequately covers the arms and legs,
especially during the early morning and late afternoon, when risk
of being bitten is the highest. Use insect repellants. For
long-term travelers, empty and clean or cover any standing water
that can be mosquito-breeding sites in the local residence (such as
water storage tanks or flowerpot trays).
Dengue Fever EpidemicWhile research is underway on developing a
vaccine to protect against dengue, this presents a challenge
because any effective vaccine would have to offer immunization
against all four types to be effective - and there is still a
limited understanding of how the disease typically behaves and how
the virus interacts with the immune system.There are also few
laboratory animal models available to test immune responses to
potential vaccines - but nevertheless two vaccine candidates have
already advanced to evaluation in human subjects in countries with
endemic disease, and several potential vaccines are in the earlier
stages of development - however an effective dengue vaccine for
public use will not be available for 5 to 10 years.There are
several reasons for the dramatic global emergence of Dengue fever
and Dengue hemorrhagic fever as a major public health problem but
they are complex and not well understood.Several important factors
have been identified - major global demographic changes have
occurred resulting in uncontrolled urbanization and concurrent
population growth, often accompanied by substandard housing and
inadequate water, sewer, and waste management systems, all of which
increase mosquito populations and facilitates the transmission of
mosquito-borne diseases.Also in most countries public health
infrastructures have deteriorated and limited financial and human
resources and competing priorities have resulted in a "crisis
mentality" with an emphasis on implementing so-called emergency
control methods in response to epidemics, rather than developing
programs to prevent epidemic transmission.This approach has been
particularly detrimental to dengue control because, in most
countries, surveillance is, as in the U.S., is passive and the
systems used to detect increased transmission normally relies on
reports by local doctors who often do not consider Dengue in their
differential diagnoses and as a result, an epidemic has often
reached or passed its peak before it is recognized.Increased travel
by airplane also provides the ideal mechanism for infected human
transport of Dengue viruses between population centers of the
tropics, resulting in a frequent exchange of Dengue viruses and
other pathogens.In addition effective mosquito control is virtually
nonexistent in most Dengue-endemic countries and the outlook for
reversing the recent trend of increased epidemic activity and
geographic expansion of dengue, is not promising.Experts say new
Dengue virus strains and serotypes are likely to continue to be
introduced into many areas where the mosquito population is high
and no new mosquito control technology available.
Despite public health authorities in many countries emphasizing
disease prevention and mosquito control through community efforts
to reduce larval breeding sources, this approach will probably only
be effective in the long term and is unlikely to impact disease
transmission in the near future.Disease experts believe improved,
proactive, laboratory-based surveillance systems must be developed
to provide early warning of an impending Dengue epidemic to allow
the public to take action and doctors to diagnose and properly
treat Dengue and Dengue haemorrhagic fever cases.The threat to
public health posed by Dengue, has been recognized by the National
Institute of Allergy and Infectious diseases (NIAID) which is
funding nearly 60 Dengue research projects, including studies on
Dengue haemorrhagic fever and Dengue shock syndrome, the most
severe forms of the disease.According to the WHO the Aedes
albopictus mosquito, a secondary Dengue vector in Asia, has now
become established in the United States, several Latin American and
Caribbean countries, parts of Europe and Africa, largely attributed
to the international trade in used tires, a known breeding
habitat.References
Harrisons Principles of Internal Medicine, 18th Edition Volume
1: McGraw Hill, 2012
Mandell, Douglas, and Burrets Principles and Practices of
Infectious Diseases, 6th Edition Volume 1: 2005 Ellen M. Slaven,
Susan C. Stone, Fred A. Lopez, Infectious Diseases: Emergency
Department Diagnosis and Management, 2007
Deanna E. Grimes, RN, DrPh, Infectious Diseases, 1991
Shirley Ooi, Guide to the Essentials in Emergency Medicine,
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Management of the Child with a Serious Infection or Severe
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http://www.nlm.nih.gov/medlineplus/ency/article/001373.htm
http://www.healthcaremedicalclinic.com/news-view.php?view=66
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC440621/
http://www.wtsp.com/news/science/article/324070/67/5-reasons-why-mosquitoes-love-you
http://www.denguevirusnet.com/history-of-dengue.html
http://www.medindia.net/patients/patientinfo/dengue-treatment.html
http://www.who.int/csr/disease/dengue/en/
http://www.who.int/mediacentre/factsheets/fs117/en/
http://www.medicinenet.com/dengue_fever/page3.htm
