Dengue febrility and dandy fever hemorrhagic febrility were foremost identified in the 1950s, during the dandy fever epidemics in Philippines and Thailand and by 1975 it had become a prima cause of hospitalization and decease among kids in many states found in that part ( Lloyd, 2003 ) . In the twelvemonth 1779 Egypt and Java had dengue-like epidemics, but it is thought that they were caused by the chikungunya virus ( Carey, 1971 ) .
Dengue virus belongs to the genus Flavivirus, Family Flavivaridae and there are four serotypes of the virus ( DEN-1, DEN-2, DEN-3 and DEN – 4 ) . All the four serotypes can do dandy fever febrility, dandy fever hemorrhagic febrility and even dengue daze syndrome ( Ramchurn et al, 2009 ) . The four viruses are closely related but are distinguishable. Millions of people shacking in tropical countries of the universe are affected by epidemics of dandy fever febrility. Dengue febrility is associated with the terrible signifier dandy fever hemorrhagic fever/ dandy fever daze syndrome ( DHF/DSS ) that is seen largely in kids and nevertheless grownups besides are attained by the disease.
In the 19th and early twentieth centuries dengue or dengue-like epidemics were reported in the Middle East, Southern Europe, Asia, North Africa, the Americas, and Australia and on assorted islands found in the Indian Ocean, South and Central Pacific and the Caribbean ( Ehrenkranz et al, 1971 ) . Generally these epidemics consisted of nonfatal hectic unwellnesss, frequently coupled with roseola and either musculus or joint strivings ( Carey, 1971 ) . In 1897 during dandy fever epidemics in Australia and in Greece in 1928, over 1000 deceases were reported ( Halstead, 1980 ) . Hemorrhagic presentations, including GI hemorrhage, were seen during epidemics of dandy fever in Texas and Louisiana in the twelvemonth 1922 ( Scott, 1923 ) . Nonetheless through the earliest half of the twentieth century, dandy fever was by and large thought to be a self-limited, nonfatal febrile unwellness, with occasional haemorrhagic manifestations such as ruddy musca volitanss, acute bleeding from the anterior naris, rhinal pit, or nasopharynx, gingival hemorrhage and hypermenorrhea that merely one time in a bluish Moon resulted in more austere or fatal results ( Gubler et al. 1992 ) .
During the last decennary, dengue infection along with its complications has been on the rise all over the universe. Their geographical spread is increasing: merely 5 states documented dandy fever in the 1950 ‘s but to day of the month there are more than 100 states describing the incidence of dandy fever febrility and dandy fever hemorrhagic febrility ( Guha -Sapi & A ; Schimmer, 2005 ) . Dengue is found in tropical and sub-tropical climes worldwide, largely in urban and semi-urban countries ( WHO, 2009 ) .
Dengue febrility is a really infective mosquito borne viral disease characterized by either a mild feverish syndrome or the authoritative incapacitating disease with disconnected oncoming of high febrility, terrible concern, hurting behind the eyes, musculus and bone or joint strivings, sickness and emesis and roseola. Skin bleedings are non uncommon. Leukopenia is normally seen and thrombopenia may be observed ( WHO 1997 ) .
Dengue is a flu-like mosquito-borne disease and has a surging capacity for epidemic eruptions, which harmonizing to the World Health Organization ( 2009 ) affects 50-100 million people each twelvemonth in the tropical and sub-tropical countries of the universe. Dengue is cited as being one of the most important mosquito-borne disease impacting worlds and as a major international public wellness concern ( WHO 2009 ) . Dengue febrility is preponderantly transmitted by Aedes species which have adapted themselves to populating near human habitation ( Hales et al. , 2002 ) .
The dandy fever virus is a member of the household Flaviviridae virus, transmitted through the biting of septic Aedes aegypti and Aedes albopictus mosquito. The Aedes aegypti mosquito usually bites indoor and late in the afternoon whereas the proficient mosquito Aedes albopictus is an aggressive daylight biter, which is besides known to seize with teeth early in the forenoon, late afternoon ( Knight and Hull, 1952 ) and at dark ( Murray and Marks, 1984 ) . This biter is normally an out-of-door biting mosquito, but it besides bites indoors ( Hawley, 1988 ) . By and large the mosquitoes bite at land degree ( MacDonald and Traub, 1960, cited in Hawley, 1988 ) . Females will seize with teeth any country of open tegument, but prefer the mortise joints and articulatio genuss ( McClelland et al. , 1973 ; Robertson and Hu, 1935 ) . The clip amid the bite of a mosquito transporting dandy fever virus and the phantom of symptoms scopes from 4 to 6 yearss, with a scope of 3 to 14 yearss.
2.0.2 Pathogenicity of Dengue febrility:
1. Asymptomatic and mild infection
It is really common.
2. Dengue Fever ( primary infection )
Dengue febrility is characterized by addition in body temperature ; terrible ache of the brow ; retro-ocular hurting ; musculus and joint hurting ; and widespread maculopapular redness. Conjunctiva may go ruddy. Other common jobs that may originate are diarrhea, purging, sickness and abdominal hurting. Fear of visible radiation, sore pharynx, addition in the size of the lymph node and shed blooding inclinations may besides go on. The unwellness lasts 5 to 7 yearss.
Unsusceptibility is womb-to-tomb. On the other side the incidence of Dengue Hemorrhagic Fever or Dengue Shock syndrome additions if the individual has unsusceptibility or has already been infected before with a different serotype. Even after several months of recovery some patients may see depression and weariness.
3. Dengue Hemorrhagic febrility
The well-known characteristic is shed blooding. It happens when a individual is infected twice but with a different dandy fever virus serotypes or infrequently by primary infection is common in childs Under 15 old ages of Age ( Rigall-Pewrez et al.1998 ) . There is sudden rise in temperature and other manifestations of Dengue febrility. Petechiae, effortless bruising, gingival hemorrhage and nosebleed are common. In terrible instances shed blooding of the GI piece of land can be observed. In kids, we can hold an addition in the size of the lien and the liver.
4. Dengue Shock Syndrome
The outstanding characteristic is hypotension. It usually occurs in people below 15 old ages of age. The clinical characteristics include weak pulsation with narrow blood force per unit area, cold and clammy tegument ( Rigall-Pewrez et al.1998 ) .
2.0.3 Mode of transmittal of dengue virus:
Dengue and chikungunya viruses are transmitted to worlds by the bites of septic mosquitoes. In contrast, Aedes albopictus can be easy found and may be the lone cardinal vector of these viruses on the islands. Both species bite largely during the daylight, preponderantly in the early hours following morning and for 2-3 hours prior to darkness. Aedes albopictus is more active out-of-doorss whereas Ae. aegypti typically provenders and rests more indoors ( WHO 2008 ) .
In the rhythm of dandy fever, the craniate host is adult male and the Aedes species the vectors. The disease is acquired merely when bitten by female mosquitoes, as the female provender on blood in order for the development of their eggs whereas the male mosquitoes are non infective due to the fact that they feed merely on nectars instead than blood. In 8-10 yearss the septic mosquito is able to convey the virus to other people. Thus the rhythm of transmittal takes merely 14 yearss. One dengue-infected female mosquito is capable of seize with teething and infecting several people during one eating session.
The dandy fever mosquito frequents backyards in hunt of containers keeping H2O inside and outside the place, such as: tins, pails, jars, and vases, pot works dishes, birdbaths, boats, tyres – discarded with no rims, roof troughs blocked by foliages striking containers, tarpaulins and black plastic.
Figure 2.1: screening blocked province of rain H2O drain and a good site for genteelness of mosquitoes.
It can besides engender in natural containers like:
fallen palm fronds.
In drier conditions it besides breeds in H2O inA subterraneous sites such as: Wellss, telecommunication cavities, sump cavities, gully traps.
Transmission rhythm of dengue consequences from a complex system based on several chief components like: the denseness of susceptible hosts, environmental conditions and the presence of one or more serotypes of the dandy fever virus. The figure of confirmed dandy fever instances has been increasing owing to the fact that the universe is undergoing rapid urbanisation and its population is besides on the rise, disposal of non-biodegradable containers, rapid transit and hapless life conditions such as hapless H2O supply and really rare scavenging services at chunky countries ( Satwant, 2001 ) .
Assorted surveies have shown that the Aedes albopictus is able to convey all the 4 serotypes of dandy fever. Aedes albopictus mosquito can function as an of import care vector of dandy fever viruses in endemic countries, and new endemic countries may be initiated by importing of vertically infected eggs ( Gubler, 2002 ) . That is the septic Aedes mosquito can go through the dandy fever virus to its offspring and when the eggs will develop into mature mosquitoes they will be already infected, therefore capable of doing infection of human existences or even pass the virus to their offspring.
Figure 2.2: how dengue virus is transmitted by Aedes aegypti ( beginning: CDC Dengue Slideset ) .
Transmission rhythm of dandy fever virus by the Aedes aegypti mosquito starts with a individual infected with the dandy fever virus. The blood of the individual will incorporate the virus therefore go arounding in his organic structure and this is called a viraemia which will last for approximately 5 yearss. During this period, an clean female Aedes aegypti mosquito bites the septic individual and acquires the dandy fever virus.
Within the mosquito, reproduction of the dandy fever virus occurs and this procedure normally takes between 8-12 yearss, after which the female mosquito can convey the virus upon a blood repast. Once infected the virus takes 4-7 yearss to retroflex within the new host ( the individual whom the septic mosquito bite ) before origin of symptoms.
Symptoms may last from three to 10 yearss, with an norm of five yearss, after the oncoming of symptoms. Hence, the disease persists several yearss after phantom of symptoms ( CDC Dengue Slideset ) .
2.0.4 Lifecycle of Aedes mosquito:
The mosquito goes through four separate and distinguishable phases during its life rhythm ; and are as follows: Egg, Larva, pupa, and grownup. Each of these phases can be easy identified by their peculiar visual aspect ( West Umatilla ) .
Egg: Eggs are laid one at a clip and they float on the surface of the H2O. Aedes lay their eggs on moist dirt that will be flooded by H2O. Most eggs hatch into larvae within 48 hours ( Alexandria Health Dept. 2010 )
Larva: The larva lives in the H2O where they finally undergo a moult procedure to go a pupa.
Pupa: It is the non-feeding, merely and is the clip the mosquito turns into an grownup. It takes about two yearss before the grownup is to the full developed and upon complete development, the pupal tegument splits and the mosquito emerges as an grownup.
Adult: On the surface of the H2O the merely turned into grownup mosquito remainders for a dumpy clip before winging off ( West Umatilla ) .
In the Aedes mosquito household merely the female bites because it requires protein to develop eggs, hence if it bites a individual infected with the dandy fever virus the mosquito becomes infective after about 7 yearss. The mosquitoes are known to be seize with teething at a highest frequence at morning and twilight. Some more facts:
The mean lifetime of a mosquito of the genus Aedes in Nature is 2 hebdomads
Mosquitos may put eggs about 3 times in his life, and about 100 eggs are produced each clip.
The eggs can populate in dry conditions until about 9 months, after which they can hatch if it is capable to conditions, i.e nutrient and H2O
Beginning: hypertext transfer protocol: //dengue-feverdisease.blogspot.com/2008/02/lifecycle-of-aedes-mosquito.html [ accessed on 05.12.09 ]
Figure 2.4: Picture of lifecycle of Aedes mosquito in H2O
2.0.5 Probe for dengue infections:
Decrease in the figure of white blood cell and peripheral neutrophils in the blood, unnatural addition in the figure of lymph cells in blood stream and really low sum of thrombocytes in the blood.
X ray of the chest usually shows pleural gush and rarely pericardiac gush
Used to observe pericardiac gush and 2 ) presence of extra fluids in the spread amid the tissues run alonging the venters and abdominal organ.
Laboratory diagnosing is done by sensing of virus in specimen-serum at the virology research lab. Culture is done in cell line derived from A. albopictus cell. Immunoflurescent techniques are used to observe viral reproductions. The virus can be isolated in patients with febrility.
IgM is noticeable in 90 % of patients by the 6th yearss of unwellness. Serum collected early may give false negative consequence. IgM can besides be detected 2-3 months after. It is non possible to place serotype with serological trials. In instance where the IgM trial is Positive it may connote recent infection with Dengue febrility. However unequivocal diagnosing can merely be made if the virus is isolated or the virus genome is detected by PCR. Seroconversion or encouragement in titre may bespeak fresh infection.
The appropriate samples for PCR trial include plasma and serum. Molecular trial is extremely sensitive but it can be used in patients merely with viremia ( Rigall-Pewrez et al.1998 ) .
The managing of dandy fever febrility can be enhanced with bed remainder, passable fluid consumption, plus control of febrility and hurting with febrifuges in add-on to anodynes ( e.g. paracetamol ) . For the auxiliary ruthless manifestations of dandy fever virus infection, right direction requires early designation and Swift endovenous fluid permutation. Blood transfusion may be necessary in instances.
There is presently no vaccinum is available to screen against dengue infection. The current deficiency of a flourishing vaccinum against the dandy fever virus causes bar methods to be approached by plumping disease vector population, with Integrated Pest Management plans for mosquito control.
These employ a odds and ends of control schemes, including mosquito surveillance, beginning decline, eliminating larvae and eliminating grownup mosquitoes ( Ooi et al. 2007 ) . Eliminating grownup mosquitoes entirely is bootless in commanding mosquito populations because it is complex to handle the unachievable home ground of the grownups. Mosquito larvae are left to transport on their development, and they rapidly swap the grownups. However, mosquitoes can go immune if pesticides are overused.
2.0.7 Dengue febrility in Mauritius:
Dengue virus infections are emerging as the major 1s in Southeast Asia. Global heating may decline the happening of dandy fever febrility. Since really last few old ages assorted eruption of chikungunya and periodic instances of dandy fever febrility have been reported on Reunion Island and other South West Indian Ocean states. From March 2005 till March 2006 it is estimated that about 204000 people in Reunion Island may hold been infected by the chikungunya virus, which moreover shows that there is presence of the conveying vectors of the disease on the island which are besides the vectors of dandy fever febrility every bit good. Hereafter, the other South West Indian ocean states were non spared from infection from the chikungunya virus.
An eruption of dandy fever febrility was reported in Madagascar more specifically in the metropolis of Toamasina that started mid-January 2006 and rare instances of chikungunya were besides reported mid-February. Maldives besides have suffered from a dandy fever eruption in twelvemonth 2006 where 602 people were suspected to be infected among which there were some terrible signifier of dandy fever febrility that is 64 dandy fever hemorrhagic febrility instances and 9 instances of dandy fever daze syndrome ( WHO 2006 ) .
In Mauritius the first instance of dandy fever febrility day of the months to the 1976 ‘s and it was contained therefore restricting the disease from distributing. Then we had a instance of imported dandy fever from a individual who visited an endemic dandy fever country in January 2008 ( CDCU ) . The chief vectors of the disease remain the Aedes mosquitoes, among which the Aedes aegypti mosquito is the primary vector and Aedes albopictus the secondary 1. The mosquito found to be distributing dengue febrility and Chikungunya in Mauritius is the Aedes albopictus ( CDCU 2009 ) . It is to be noted that in Mauritius we had both the Aedes aegypti and Aedes albopictus mosquitoes, due to the intense anti-malaria run during the twelvemonth 1952 the primary bearer of the dandy fever febrility, the Aedes aegypti have been successfully eradicated. Still really infinitesimal sums of this mosquito can be seen whereas the Aedes albopictus is abundant. Dengue is transmitted from individual to individual through the biting of septic mosquitoes.
Most late we had a ephemeral epidemic of re-emerged dandy fever febrility in Mauritius that started in the month of June 2009 which was imported. The mild febrility was foremost localized in the metropolis of Port Louis, where there were 192 instances and so we did hold some sporadic instances in other parts of the island. Mosquito fogging and larviciding in whole Port Louis started on 3rd June 2009, and were repeated every seven yearss. Obscuring was carried out out-of-doorss early in the forenoon, early eventides and sometimes till tardily in the eventides ( Dengue Unit 2009 ) .
The Ministry of Health and Quality of Life of Mauritius took the state of affairs as being terrible and all medium possible to incorporate the disease were put into action. Like the Special Mobile Force and work force from other Ministries which joined the Ministry of Health to contend the dandy fever febrility. Public alertness runs on the necessity to run and extinguish mosquito engendering sites at place and in the vicinity and to protect oneself against mosquito bites were carried out through wireless, telecasting and the imperativeness through a public private partnership. Detailed information cusps were besides distributed, door to door distribution of booklets demoing images of possible genteelness sites for mosquitoes and merchandises to be used to forestall mosquito bite were carried out by the primary wellness attention forces. Target groups included the populace, community groups and school kids ( Ramchurn et al, 2009 ) .
By the terminal of the month August no new or suspected instances of dandy fever were recorded in any of the state ‘s infirmary. But still the control and bar plan were continued throughout the island as the summer season was coming near hence reappearance of the dandy fever febrility was possible due to the ambient temperature, favourable for larvae development. The fright of holding the virus once more was due to the possibility of the septic mosquitoes to go through the virus to their offspring. Fortunately, till February 2010 no suspected instance of dandy fever febrility was reported from any in the state ( Dengue Unit 2010 ) .
2.1 Vector surveillance and control plan
Ever since mosquitoes are capable of conveying diseases like dandy fever and chikungunya, till now it has non been possible to eliminate the mosquitoes wholly from their arising site. The best manner to supervise or command vector-borne diseases is to command or restrict the population of the vector to such an extent that disease transmittal is really low or even stopped. In order to accomplish this end, it is imperative to cognize all about the mosquito involved in the transmittal of the disease.
Detailed cognition of all facets such as the genteelness sites, different characteristics of the mosquito at different phases, feeding wonts, coupling, resting and construction and most significantly without burying the lifecycle of the mosquito, are the chief needed things in order to be able to interrupt the concatenation of transmittal. Furthermore, the lone manner to forestall infection of people who have non suffered from dandy fever is to command the population of dandy fever vector ( Ooi et al.2001 ) and of class personal safeguard has besides proved to be effectual in cut downing the hazard of being infected by a mosquito.
Since no vaccinum is yet available for dandy fever the lone manner to command dandy fever febrility is the control the sum of the disease vector that is of the Aedes mosquitoes. The control schemes of these mosquitoes are 1 ) transporting out larviciding -spraying a chemical called abate in any H2O retaining topographic point which kill the larvae of the mosquitoes therefore disrupting the rhythm to be completed, 2 ) obscuring operation- a thermic fogger is used to impel exhausts of Aqua K-OthrineA® which when is in contact with a mosquito kills it, therefore the sum of developed or merely mature mosquitoes are reduced and 3 ) wellness education- negotiations are organized for the members of the populace, for kids in schools, colleges, etcaˆ¦
Entomological study is an of import and built-in portion of dandy fever bar and control. The consequence of the intercession by the community can straight impact the ecology of the vectors that is the Aedes mosquitoes.
The Catching Disease Control Unit ( CDCU ) is the unit which is largely concerned for the control of catching diseases such as Malaria, Dengue febrility, Chikungunya, and other infective diseases. In Mauritius, surveillance, disease bar and instruction of infective diseases are chiefly carried out by the Health Inspectorate Cadre. In Mauritius, we have the Public Health Act ( Section 32A ) which is used in instance where there is presence of a mosquito borne disease in the island.
The potency for predation to forestall pathogen invasion or cut down disease prevalence in a host population besides has deductions for the biological control of vector populations. Marauders have been introduced, or proposed, as biological control agents of vectors for assorted diseases such as malaria, dandy fever febrility and Lyme disease ( Jenkins 1964 ; Legner 1995 ; Stauffer et al. 1997 ; Samish & A ; Rehacek 1999 ; Scholte et Al. 2005 ; Kumar & A ; Hwang 2006 ; Ostfeld et Al. 2006 ; Walker & A ; Lynch 2007 ) . Several recent surveies suggest that marauder debuts led to a diminution in local instances of dandy fever febrility in Vietnam and Thailand ( Kay & A ; Nam 2005 ; Kittayapong et Al. 2008 ) , and malaria in India ( Ghosh et al. 2005 ; Ghosh & A ; Dash 2007 ) .
2.2 Biology of Aedes albopictus ( Skuse )
Aedes albopictus are two winged insects from the household Culicidae of the order Diptera. They are among the best known groups due to their importance as plagues and as vectors of diseases. They are easy identified due to a combination of the undermentioned characters: long bole projecting caput ; personal appeal of graduated tables on the wing venas, a tassel of graduated tables along the posterior boundary of the wing, and the typical wing venation, the 2nd, 4th and 5th longitudinal venas being branched ( Miyagi and Toma 2000 ) .
Female mosquitoes feed on blood and they have extremely specialized mothparts for piercing host tegument and blood suction ( Wahid et al. 2002 ) . Aedes species are usually day-time bitters and active during the twenty-four hours. During this clip, they have extremums of landing and biting activity. The peak clip for Aedes albopictus occurred about one hr after dawn and so earlier sundown ( Abu Hassan et Al. 1996 ) . However, the rate of seize with teething varies depending on the mosquito age and clip of the twenty-four hours ( Xue and Barnard 1996 ) .