FIEBRE CHIKUNGUNYA

diciembre 27, 2007

La Fiebre Chikungunya es una enfermedad viral producida por un alfavirus de la familia togaviridae y transmitida por la picadura de mosquitos Aedes aegypti. Hasta ahora estuvo confinada a áreas tropicales de África, Asia e islas del Océano Indico. Este es el primer brote de casos autóctonos ocurrido en la Comunidad Europea. (Italia) El vector fue el Aedes albopictus (mosquito tigre asiático).

La extensión de la enfermedad a otros países estará determinada por el calentamiento global, las migraciones y la movilización de personas en el mundo globalizado y la presencia de grandes poblaciones de vectores.
Los síntomas son parecidos a los del dengue, si bien, se agregan característicamente artralgias que obligan a adoptar al paciente posiciones antálgicas. De esto proviene el nombre de la enfermedad en swahilí (Tanzania).

En Venezuela no se han identificado casos de Fiebre Chikungunya, pero si de Fiebre Mayaro un virus muy parecido de la misma familia y género que produce manifestaciones similares con artralgias persistentes e incapacitantes. El el año 2000 se reportó por primera vez la enfermedad en nuestro país; afectó a los miembros de una familia residente en un área rural de Barlovento, quienes se expusieron a la picadura masiva de mosquitos Haemagogus.
Torres JR, Russell KL, Vasquez C, Barrera R, Tesh RB, Salas R et al. Family clustser of Mayaro fever, Venezuela. Emerg Infect Dis [serial on the Internet]. 2004 Jul [date cited]. Available from: http://www.cdc.gov/ncidod/EID/vol10no7/03-0860.htm

La suspensión del Boletín epidemiológico del MPPS como fuente de información confiable, nos priva de un instrumento valioso para la vigilancia epidemiológica de enfermedades emergentes y reemergentes, en razón de lo cual acudo a las siguientes fuentes bibliográficas:

FACT SHEET DEL CDC, el Reporte del Brote italiano en el SISTEMA DE VIGILANCIA EPIDEMIOLÓGICA DE LA COMUNIDAD EUROPEA y el artículo publicado en el NEW YORK TIMES (Europa) el día 23-12-2007, amablemente remitido por el Dr. Francisco Kerdel-Vegas.

Chikungunya Fever Fact Sheet

www.cdc.gov/ncidod/dvbid/Chikungunya/chikvfact.htm+Chikungunya&hl=en&ct=clnk&cd=2

What is chikungunya fever?
Chikungunya fever is a viral disease transmitted to humans by the bite of infected mosquitoes. Chikungunya virus (CHIKV) is a member of the genus Alphavirus, in the family Togaviridae. CHIKV was first isolated from the blood of a febrile patient in Tanzania in 1953, and has since been identified repeatedly in west, central and southern Africa and many areas of Asia, and has been cited as the cause of numerous human epidemics in those areas since that time. The virus circulates throughout much of Africa, with transmission thought to occur mainly between mosquitoes and monkeys. 

What type of illness does chikungunya virus cause?
CHIKV infection can cause a debilitating illness, most often characterized by fever, headache, fatigue, nausea, vomiting, muscle pain, rash, and joint pain. The term "chikungunya" is thought to be derived from the word "kungunyala" in the Makonde language of southeastern Tanzania and northern Mozambique, which means "to dry up or become contorted".

The incubation period (time from infection to illness) can be 2-12 days, but is usually 3-7 days. "Silent" CHIKV infections (infections without illness) do occur; but how commonly this happens is not yet known.

Acute chikungunya fever typically lasts a few days to a couple of weeks, but as with dengue, West Nile fever, o'nyong-nyong fever and other arboviral fevers, some patients have prolonged fatigue lasting several weeks. Additionally, some patients have reported
incapacitating joint pain, or arthritis which may last for weeks or months. The prolonged joint pain associated with CHIKV is not typical of dengue. Co-circulation of dengue fever in many areas may mean that chikungunya fever cases are sometimes clinically misdiagnosed as dengue infections, therefore the incidence of chikungunya fever could be much higher than what has been previously reported.

No deaths, neuroinvasive cases, or hemorrhagic cases related to CHIKV infection have been conclusively documented in the scientific literature.

CHIKV infection (whether clinical or silent) is thought to confer life-long immunity.

How do humans become infected with chikungunya virus?
CHIKV is spread by the bite of an infected mosquito. Mosquitoes become infected when they feed on a person infected with CHIKV. Monkeys, and possibly other wild animals, may also serve as reservoirs of the virus. Infected mosquitoes can then spread the virus to other humans when they bite.

Aedes aegypti (the yellow fever mosquito), a household container breeder and aggressive daytime biter which is attracted to humans, is the primary vector of CHIKV to humans. Aedes albopictus (the Asian tiger mosquito)may also play a role in human transmission is Asia, and various forest-dwelling mosquito species in Africa have been found to be infected with the virus.

Where does chikungunya virus occur?
The geographic range of the virus is Africa and Asia. For information on current outbreaks, consult CDC's Travelers' Health website (www.cdc.gov/travel). Given the current large CHIKV epidemics and the world wide distribution of Aedes aegypti, there is a risk of importation of CHIKV into new areas by infected travelers.

How is chikungunya virus infection treated?
No vaccine or specific antiviral treatment for chikungunya fever is available. Treatment is symptomatic–rest, fluids, and ibuprofen, naproxen, acetaminophen, or paracetamol may relieve symptoms of fever and aching. Aspirin should be avoided

Infected persons should be protected from further mosquito exposure (staying indoors and/or under a mosquito net during the first few days of illness) so that they can't contribute to the transmission cycle.

What can people do to prevent becoming infected with chikungunya virus?
The best way to avoid CHIKV infection is to prevent mosquito bites. There is no vaccine or preventive drug. Prevention tips are similar to those for dengue or West Nile virus:

    * Use insect repellent containing an DEET or another EPA-registered active ingredient  on exposed skin. Always follow the directions on the package.
    * Wear long sleeves and pants (ideally treat clothes with permethrin or another repellent).
    * Have secure screens on windows and doors to keep mosquitoes out.
    * Get rid of mosquito breeding sites by emptying standing water from flower pots, buckets and barrels. Change the water in pet dishes and replace the water in bird baths weekly. Drill holes in tire swings so water drains out. Keep children's wading pools empty and on their sides when they aren't being used.
    * Additionally, a person with chikungunya fever or dengue should limit their exposure to mosquito bites in order to avoid further spreading the infection. The person should stay indoors or under a mosquito net.

Chikungunya Fever, a re-emerging Disease in Asia

http://www.searo.who.int/en/Section10/Section2246.htm

Chikungunya fever, is a viral illness that is spread by the bite of infected mosquitoes. The disease resembles dengue fever, and is characterized by severe, sometimes persistent, joint pain (arthritis), as well as fever and rash. It is rarely life-threatening. Nevertheless widespread occurrence of diseases causes substantial morbidity and economic loss

Epidemiology

Epidemics of fever, rash and arthritis, resembling Chikungunya fever have been recorded as early as 1824 in India and elsewhere. However, the virus was first isolated between 1952-1953 from both man and mosquitoes during an epidemic of fever that was considered clinically indistinguishable from dengue, in the Tanzania.

Chikungunya fever displays interesting epidemiological profiles: major epidemics appear and disappear cyclically, usually with an inter-epidemic period of 7-8 years and sometimes as long as 20 years. After a long period of absence, outbreaks of CHIK fevers have appeared in Indonesia in 1999.

Chikungunya in Asia (1960-1982)

Between 1960 and 1982, outbreaks of Chikungunya fever were reported from Africa and Asia.  In Asia, virus strains have been isolated in Bangkok in 1960s; various parts of India including Vellore, Calcutta and Maharastha in 1964; in Sri Lanka in 1969; Vietnam in 1975; Myanmar in 1975 and Indonesia in 1982.

Recent occurrences of chikungunya fever

After an interval of more than 20 years, chikungunya fever has been reported from several countries including India, and various Indian Ocean islands including Comoros, Mauritius, Reunion and Seychelles.

Chikungunya fever in India

Till 10 October 2006, 151 districts of eight states/provinces of India have been affected by chikungunya fever. The affected states are Andhra Pradesh, Andaman & Nicobar Islands, Tamil Nadu, Karnataka, Maharashtra, Gujarat, Madhya Pradesh, Kerala and Delhi.

More than 1.25 million cases have been reported from the country with 752,245 cases from Karnataka and 258,998 from Maharashtra provinces. In some areas attack rates have reached up to 45%.

Chikungunya and dengue fevers

The clinical manifestations of chikungunya fever have to be distinguished from dengue fever. Co-occurrence of both fevers has been recently observed in Maharashtra state of India thus highlighting the importance of strong clinical suspicion and efficient laboratory support.   

Laboratory Diagnosis

The clinical manifestations of chikungunya fever resemble those of dengue fever. Laboratory diagnosis is critical to establish the cause of diagnosis and initiate specific public health response.

Treatment, prevention and control

Treatment

Chikungunya fever is not a life threatening infection. Symptomatic treatment for mitigating pain and fever using anti-inflammatory drugs along with rest usually suffices. While recovery from chikungunya is the expected outcome, convalescence can be prolonged (up to a year or more), and persistent joint pain may require analgesic (pain medication) and long-term anti-inflammatory therapy.

Prevention and control

No vaccine is available against this virus infection. Prevention is entirely dependent upon taking steps to avoid mosquito bites and elimination of mosquito breeding sites.

To avoid mosquito bites:

*     Wear full sleeve clothes and long dresses to cover the limbs;

*     Use mosquito coils, repellents and electric vapour mats during the daytime;

*     Use mosquito nets – to protect babies, old people and others, who may rest during the day. The effectiveness of such nets can be improved by treating them with permethrin (pyrethroid insecticide). Curtains (cloth or bamboo) can also be treated with insecticide and hung at windows or doorways, to repel or kill mosquitoes.

*     Mosquitoes become infected when they bite people who are sick with chikungunya. Mosquito nets and mosquito nets and mosquito coils will effectively prevent mosquitoes from biting sick people.

To prevent mosquito breeding

The Aedes mosquitoes that transmit chikungunya breed in a wide variety of manmade containers which are common around human dwellings. These containers collect rainwater, and include discarded tires, flowerpots, old oil drums, animal water troughs, water storage vessels, and plastic food containers. These breeding sites can be eliminated by

*      Draining water from coolers, tanks, barrels, drums and buckets, etc.;

*      Emptying coolers when not in use;

*      Removing from the house all objects, e.g. plant saucers, etc. which have water collected in them

*      Cooperating with the public health authorities in anti-mosquito measures.

Role of public health authorities

*     National programme for prevention and control of vector borne diseases should be strengthened and efficiently implemented with multisectoral coordination

*     Legislations for elimination of domestic/peridomestic mosquitogenic sites should be effectively enforced

*     Communities must be made aware of the disease and their active cooperation in prevention and control measures elicited 

Chikungunya in north-eastern Italy: a summing up of the outbreak
http://www.eurosurveillance.org/ew/2007/071122.asp#2

R Angelini1, AC Finarelli2, P Angelini2, C Po2, K Petropulacos3 G Silvi1, P Macini2, C Fortuna4, G Venturi4, F Magurano4, C Fiorentini4, A Marchi4, E Benedetti4, P Bucci4, S Boros4, R Romi4, G Majori4, MG Ciufolini4, L Nicoletti4, G Rezza4, A Cassone (cassone@iss.it)4

1. Dipartimento Sanità Pubblica, Azienda Unità Sanitaria Locale (Department of Public Health, Local Health Unit), Ravenna, Italy
2. Servizio di Sanità Pubblica, Regione Emilia-Romagna, Bologna, Italy
3. Servizio Presidi Ospedalieri, Regione Emilia-Romagna, Bologna, Italy
4. Department of Infectious, Parasitic and Immunomediated Diseases, Istituto Superiore di Sanità, Rome, Italy

Laboratory results
The first outbreak of autochthonously transmitted Chikungunya virus (CHIKV) in Europe, which recently occurred in the province of Ravenna in north-eastern Italy [1,2], has been completely controlled: the last case onset occurred on 28 September in the town of Rimini, and in October no cases were confirmed. Of the 334 suspected or probable CHIKV cases involved in the outbreak, samples were examined of 281 and 204 were laboratory-confirmed by PCR, Hemagglutination-inhibition or both. Reasonably, the number of laboratory-confirmed cases most likely constitutes an underestimate of the extent of the outbreak, since blood or serum samples were not available for all of the individuals who fulfilled the clinical and/or epidemiological criteria of the case-definition.

Geographical distribution of cases
Most cases were reported among persons living in or visiting the initially affected villages of Castiglione di Cervia and Castiglione di Ravenna. Four smaller clusters of local transmission were also detected in four towns in the same region (i.e., Cervia, Cesena, Ravenna, and Rimini) which are located 9 to 49 km from the initially affected villages. For at least three of the four clusters, population movement (i.e., persons who visited the area that was primarily affected or persons from the primarily affected area who visited one of the four towns) can be reasonably assumed to have been the main determinant of local transmission. However, if this was the case, the question arises as to why no previous outbreaks of CHIKV occurred in other Italian regions in 2005-2006 (after the epidemic in Reunion), when at least 30 infected travellers returned to locations infested by mosquito vector populations [3]; the same question arises for several hundred cases reported among travellers returning from affected areas to a number of European countries in the same period [3,4,5]. Possible explanations include: i) high concentration of vectors in the affected towns; ii) highly viremic persons exposing themselves to aggressive Aedes albopictus populations as a consequence of the structures of houses and/or behavioural factors (e.g., spending time outdoors in houses' surroundings).

Overall, the epidemic in Italy can be said to be the result of the combined effect of the globalisation of vectors and humans, which occurred through a two-step process: i) the introduction and adaptation of the vector Ae. albopictus to a new environment (i.e., a temperate climate); and ii) the introduction of CHIKV in a previously infection-free country, with totally susceptible subjects, as the result of population movement (i.e., travelling human hosts, acting as a sort of Trojan Horse). However, the epidemic was limited in space and time, with a marked decay rate since the adoption of appropriate control measures (albeit they were taken at different times in different locations). In addition, there is probably a time-limited capacity of the vector to sustain infection transmission beyond the hot season in a country with a temperate climate.

What did we learn from the Italian epidemic?

    * Vector-borne diseases, historically confined to tropical environments, can be introduced within Europe if the conditions are appropriate (i.e., the presence of vectors). The major determinant of the outbreak in Italy was probably the high vector density at the time of arrival of the index case, which could be explained by the lack of preventive vector-control measures in an area that was considered to be 'infection-free';
    * The vectorial capacity of Ae. albopictus for CHIKV is high [6]. A few hours spent in a highly vector-dense village by only one feverish patient caused a large outbreak in a naïve population;
    * As seen for other infectious diseases causing international crises (i.e., SARS), population movement and vector colonisation of new areas are important determinants of disease globalisation.

Nonetheless, there are still some questions that need to be investigated further:

    * Why did a single case result in an outbreak while none of the many CHIVK-infected travellers have caused local transmission upon returning home to Italy or other European countries in roughly similar vector-dense areas;
    * Has the infection been eradicated in the affected area or could it reappear at the beginning of the next hot season due to overwintering?
    * What is the probability that other similar events will occur in Italy or other European countries where Ae. albopictus is present, and could other infections, such as Dengue, cause similar outbreaks in Europe?

These questions need to be adequately answered so as to strengthen activities for the surveillance and control of Ae. albopictus and other vectors of exotic infectious diseases (i.e., Chikungunya and others) and to perform early diagnosis of viral agents that can be imported and transmitted in Europe. Furthermore, more intense research efforts should be promoted in Italy and in Europe on the mosquito-virus relationship, as well as in other critical areas concerning vaccine and specific antiviral drugs. Experimental infections in vector populations, virus and vector genotyping are some of the specific investigations already planned in Italy.

References:

   1. Angelini R, Finarelli AC, Angelini P, Po C, Petropulacos K, Macini P, Fiorentini C, Fortuna C, Venturi G, Romi R, Majori G, Nicoletti L, Rezza G, Cassone A. An outbreak of chikungunya fever in the province of Ravenna, Italy. Euro Surveill 2007;12(9):E070906.1. Available from: http://www.eurosurveillance.org/ew/2007/070906.asp#1
   2. G Rezza, L Nicoletti, R Angelini, R Romi, AC Finarelli, M Panning, P Cordioli, C Fortuna, S Boros, F Magurano, G Silvi, P Angelini, M Dottori, MG Ciufolini, GC Majori, A Cassone Infection with Chikungunya virus in Italy : An outbreak a temperate region. Lancet, 2007, in press.
   3. Nicoletti L, Ciccozzi M, Marchi A, Fiorentini C, Martucci P, D'Ancona F, Ciofi degli Atti M, Pompa MG, Rezza G, Ciufolini MG. Correlates of Chikungunya and Dengue in travellers. Emerging Infectious Diseases, in press.
   4. Depoortere E, Coulombier D, ECDC Chikungunya risk assessment group. Chikungunya risk assessment for Europe: recommendations for action. Euro Surveill 2006;11(5):E060511.2. Available from: http://www.eurosurveillance.org/ew/2006/060511.asp#2
   5. Joint ECDC/WHO European Risk Assessment on Chikungunya in Italy: a mission report. Available from: http://www.ecdc.europa.eu/pdf/071030CHK_mission_ITA.pdf
   6. Vazeille M, Jeannin C, Martin E, Schaffner F, Failloux AB. Chikungunya: A risk for Mediterranean countries? Acta Trop. 2007 Oct 12; [Epub ahead of print].

CHIKUNGUNYA EN ITALIA

From: francisco.kerdelvegas@gmail.com
To: bitacoramedica.com@gmail.com
CC: clementea2@gmail.com; jofeol@hotmail.com; fernalamo@cantv.net
Subject: As Earth Warms Up, Tropical Virus Moves to Italy – New York Times
Date: Sun, 23 Dec 2007 19:01:05 -0500
 
 http://www.nytimes.com/2007/12/23/world/europe/23virus.html?_r=1&oref=slogin

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