sharon sanders
Editor-in-Chief & President
The Lancet Infectious Diseases 2006; 6:463-464
DOI:10.1016/S1473-3099(06)70531-X
Aedes albopictus as an epidemic vector of chikungunya virus: another emerging problem? Paul Reiter
a, Didier Fontenille b and Christophe Paupy b
A major epidemic of chikungunya fever on the island of Reunion (population 770
000) has resulted in 265
000 clinical cases (34% of the population) and 237 deaths.1 Surprisingly, Aedes (Stegomyia) aegypti, the mosquito usually implicated in such outbreaks, is virtually absent.
Chikungunya is an arbovirus of the family Togaviridae. The natural vectors of the virus are African forest mosquitoes of the subgenera Diceromyia, Stegomyia, and Aedimorphus that feed preferentially on primates.2 The ?domestic? form of A aegypti is closely associated with human habitation, readily enters houses, feeds almost exclusively on human beings, and is ubiquitous throughout the tropics. By contrast, Aedes albopictus, the species implicated in the Reunion outbreak, is of Asian origin, is often abundant far from human habitation, and feeds readily on many species of mammals and birds. In the laboratory, many A albopictus strains have a high vector competence (ie, they are readily infected by chikungunya virus),3 but in nature, they are assumed to have a low vectorial capacity (ie, efficacy as a vector) because blood meals taken from non-susceptible hosts do not contribute to the transmission cycle.4
In the Hawaiian islands, major epidemics of dengue were frequent from 1840 until the 1940s, but ceased after an energetic mosquito control campaign. A aegypti was virtually eliminated, but A albopictus remained widespread and abundant.5 Since then, despite a high rate of imported cases, there was no evidence of autochthonous transmission until a small outbreak (122 confirmed cases, 0?01% of the total population) in 2001?02. After nearly 60 years, the human herd immunity was minimal, yet there was no repeat of past epidemics. A aegypti was rare and restricted to one island, but A albopictus was ubiquitous, and super-abundant in the focus of transmission.6 By contrast, in French Polynesia, where A aegypti remains abundant, there have been ten major outbreaks of dengue since World War II, many with high morbidity and substantial mortality.7 Indeed, there is persuasive evidence that the 2001 outbreak in Hawaii was initiated by infected people arriving from Tahiti, where a major epidemic (about 33
000 cases, 14% of the total population) was under way.
The history of transmission in Hawaii versus Tahiti seems to confirm that A albopictus has a low vectorial capacity for dengue viruses compared with A aegypti, yet in 1977 there was a major outbreak of dengue 2 on Reunion, with an estimated 160
000 cases?ie, 30% of the population8?and laboratory studies confirmed high vector competence in the local A albopictus.9 As in Hawaii, the species was super-abundant, whereas A aegypti had remained rare after an effective control campaign in the 1950s.10,11 Thus, the 1977 epidemic and the current epidemic of chikungunya confirm that A albopictus can have a high vectorial capacity, at least on Reunion. The local A albopictus population may be more anthropophilic than in other parts of the world; a recent study in Thailand found some evidence of a preference for human blood.12 Alternatively, the relative abundance of human beings in the peridomestic environment could oblige the mosquito to feed on human beings. Other species could conceivably be involved in the transmission cycle. Whatever, the reasons, it is clear that the role of A albopictus as a vector should be re-assessed, both on Reunion and in other parts of the world.
Mosquito control is the sole available method for reducing transmission of chikungunya; no vaccines are available. As already mentioned, large-scale campaigns (using DDT) have been highly effective against A aegypti, but not A albopictus. Moreover, in the past three decades, even control of A aegypti has rarely been achieved and never sustained.13 Therefore, if we assume that it is possible to prevent future epidemics, we must explore new and innovative approaches, such as novel methods of using insecticides or the introduction of genetically modified strains.14
It is ironic to reflect that A aegypti, yellow fever, dengue, A albopictus, chikungunya, and West Nile virus all have a common vector: mankind. A aegypti and yellow fever were transported to the New World during the slave trade, A albopictus achieved worldwide distribution via containerised shipments of used tyres,15,16 West Nile virus almost certainly arrived in the New World in imported birds, and there is a well-documented global traffic of human viruses in aircraft passengers.17 Thus, modern transportation has produced a quantum leap in the mobility of vectors and pathogens, and the consequences of this globalisation will continue to surprise us.
<!--start simple-tail=-->References
1. Anon. Cire La R?union-Mayotte?weekly report. Epid?mie de chikungunya ? La R?union, June 22, 2006
http://www.orsrun.net
(accessed June 30, 2006).
2. Diallo M, Thonnon J, Traore-Lamizana M, Fontenille D. Vectors of Chikungunya virus in Senegal: current data and transmission cycles. Am J Trop Med Hyg 1999; 60: 281-286. MEDLINE
3. Tesh RB, Gubler DJ, Rosen L. Variation among goegraphic strains of Aedes albopictus in susceptibility to infection with chikungunya virus. Am J Trop Med Hyg 1976; 25: 326-335. MEDLINE
4. Rodhain F, Rosen L. Mosquito vectors and dengue virus-vector relationships In: Gubler DJ, Kuno G, eds. Dengue and dengue hemorrhagic fever. Wallingford, UK: CABI Publishing, 1997: 45-60.
5. Gilbertson WE. Sanitary aspects of the control of the 1943?44 epidemic of dengue fever in Honolulu. Am J Public Health 1945; 35: 261-270.
6. Effler PV, Pang L, Kitsutani P, et al. Dengue fever, Hawaii, 2001?2002. Emerg Infect Dis 2005; 11: 742-749. MEDLINE
7. Murgue B, Deparis X, Chungue E, Cassar O, Roche C. Dengue: an evaluation of dengue severity in French Polynesia based on an analysis of 403 laboratory-confirmed cases. Trop Med Int Health 1999; 4: 765-773. MEDLINE | CrossRef
8. Coulanges P, Clercy Y, Jousset FX, Rodhain F, Hannoun C. Dengue at Reunion: isolation of a strain at the Pasteur Institute of Madagascar. Bull Soc Pathol Exot Filiales 1979; 72: 205-209(in French). MEDLINE
9. Paupy C, Girod R, Salvan M, Rodhain F, Failloux AB. Population structure of Aedes albopictus from La Reunion Island (Indian Ocean) with respect to susceptibility to a dengue virus. Heredity 2001; 87: 273-283. MEDLINE | CrossRef
10. Hamon J. Etudes biologique et syst?matique des Culicinae de l'Ile de La R?union. M?moires de l'Institut Scientifique de Madagascar 1953; 4 (S?rie E): 521-541.
11. Salvan M, Mouchet J. Aedes albopictus and Aedes aegypti at Ile de la Reunion. Ann Soc Belg Med Trop 1994; 74: 323-326(in French). MEDLINE
12. Ponlawat A, Harrington LC. Blood feeding patterns of Aedes aegypti and Aedes albopictus in Thailand. J Med Entomol 2005; 42: 844-849. MEDLINE
13. Reiter P, Gubler DJ. Surveillance and control of urban dengue vectors In: Gubler DJ, Kuno G, eds. Dengue and dengue hemorrhagic fever. Wallingford, UK: CABI Publishing, 1997: 1-22.
14. Gong P, Epton MJ, Fu G, et al. A dominant lethal genetic system for autocidal control of the Mediterranean fruitfly. Nat Biotechnol 2005; 23: 453-456. MEDLINE | CrossRef
15. Reiter P, Darsie R. Aedes albopictus in Memphis, Tennessee (USA): an achievement of modern transportation?. Mosquito News 1984; 44: 396-399.
16. Reiter P, Sprenger D. The used tire trade: a mechanism for the worldwide dispersal of container breeding mosquitoes. J Am Mosq Control Assoc 1987; 3: 494-501. MEDLINE
17. Gubler DJ. Dengue and dengue hemorrhagic fever: its history and resurgence as a global public health problem In: Gubler DJ, Kuno G, eds. Dengue and dengue hemorrhagic fever. Wallingford, UK: CABI Publishing, 1997: 425-462.
Back to top
<!--end simple-tail-->Affiliations
a. Institut Pasteur, Insectes et Maladies Infectieuses, Paris, France
b. Caracterisation et Controle des Populations de Vecteurs, UR016, Institut de Recherche pour le D?veloppement, Montpellier, France
DOI:10.1016/S1473-3099(06)70531-X
Aedes albopictus as an epidemic vector of chikungunya virus: another emerging problem? Paul Reiter
a, Didier Fontenille b and Christophe Paupy bA major epidemic of chikungunya fever on the island of Reunion (population 770
Chikungunya is an arbovirus of the family Togaviridae. The natural vectors of the virus are African forest mosquitoes of the subgenera Diceromyia, Stegomyia, and Aedimorphus that feed preferentially on primates.2 The ?domestic? form of A aegypti is closely associated with human habitation, readily enters houses, feeds almost exclusively on human beings, and is ubiquitous throughout the tropics. By contrast, Aedes albopictus, the species implicated in the Reunion outbreak, is of Asian origin, is often abundant far from human habitation, and feeds readily on many species of mammals and birds. In the laboratory, many A albopictus strains have a high vector competence (ie, they are readily infected by chikungunya virus),3 but in nature, they are assumed to have a low vectorial capacity (ie, efficacy as a vector) because blood meals taken from non-susceptible hosts do not contribute to the transmission cycle.4
In the Hawaiian islands, major epidemics of dengue were frequent from 1840 until the 1940s, but ceased after an energetic mosquito control campaign. A aegypti was virtually eliminated, but A albopictus remained widespread and abundant.5 Since then, despite a high rate of imported cases, there was no evidence of autochthonous transmission until a small outbreak (122 confirmed cases, 0?01% of the total population) in 2001?02. After nearly 60 years, the human herd immunity was minimal, yet there was no repeat of past epidemics. A aegypti was rare and restricted to one island, but A albopictus was ubiquitous, and super-abundant in the focus of transmission.6 By contrast, in French Polynesia, where A aegypti remains abundant, there have been ten major outbreaks of dengue since World War II, many with high morbidity and substantial mortality.7 Indeed, there is persuasive evidence that the 2001 outbreak in Hawaii was initiated by infected people arriving from Tahiti, where a major epidemic (about 33
The history of transmission in Hawaii versus Tahiti seems to confirm that A albopictus has a low vectorial capacity for dengue viruses compared with A aegypti, yet in 1977 there was a major outbreak of dengue 2 on Reunion, with an estimated 160
Mosquito control is the sole available method for reducing transmission of chikungunya; no vaccines are available. As already mentioned, large-scale campaigns (using DDT) have been highly effective against A aegypti, but not A albopictus. Moreover, in the past three decades, even control of A aegypti has rarely been achieved and never sustained.13 Therefore, if we assume that it is possible to prevent future epidemics, we must explore new and innovative approaches, such as novel methods of using insecticides or the introduction of genetically modified strains.14
It is ironic to reflect that A aegypti, yellow fever, dengue, A albopictus, chikungunya, and West Nile virus all have a common vector: mankind. A aegypti and yellow fever were transported to the New World during the slave trade, A albopictus achieved worldwide distribution via containerised shipments of used tyres,15,16 West Nile virus almost certainly arrived in the New World in imported birds, and there is a well-documented global traffic of human viruses in aircraft passengers.17 Thus, modern transportation has produced a quantum leap in the mobility of vectors and pathogens, and the consequences of this globalisation will continue to surprise us.
<!--start simple-tail=-->References
1. Anon. Cire La R?union-Mayotte?weekly report. Epid?mie de chikungunya ? La R?union, June 22, 2006
http://www.orsrun.net
(accessed June 30, 2006).
2. Diallo M, Thonnon J, Traore-Lamizana M, Fontenille D. Vectors of Chikungunya virus in Senegal: current data and transmission cycles. Am J Trop Med Hyg 1999; 60: 281-286. MEDLINE
3. Tesh RB, Gubler DJ, Rosen L. Variation among goegraphic strains of Aedes albopictus in susceptibility to infection with chikungunya virus. Am J Trop Med Hyg 1976; 25: 326-335. MEDLINE
4. Rodhain F, Rosen L. Mosquito vectors and dengue virus-vector relationships In: Gubler DJ, Kuno G, eds. Dengue and dengue hemorrhagic fever. Wallingford, UK: CABI Publishing, 1997: 45-60.
5. Gilbertson WE. Sanitary aspects of the control of the 1943?44 epidemic of dengue fever in Honolulu. Am J Public Health 1945; 35: 261-270.
6. Effler PV, Pang L, Kitsutani P, et al. Dengue fever, Hawaii, 2001?2002. Emerg Infect Dis 2005; 11: 742-749. MEDLINE
7. Murgue B, Deparis X, Chungue E, Cassar O, Roche C. Dengue: an evaluation of dengue severity in French Polynesia based on an analysis of 403 laboratory-confirmed cases. Trop Med Int Health 1999; 4: 765-773. MEDLINE | CrossRef
8. Coulanges P, Clercy Y, Jousset FX, Rodhain F, Hannoun C. Dengue at Reunion: isolation of a strain at the Pasteur Institute of Madagascar. Bull Soc Pathol Exot Filiales 1979; 72: 205-209(in French). MEDLINE
9. Paupy C, Girod R, Salvan M, Rodhain F, Failloux AB. Population structure of Aedes albopictus from La Reunion Island (Indian Ocean) with respect to susceptibility to a dengue virus. Heredity 2001; 87: 273-283. MEDLINE | CrossRef
10. Hamon J. Etudes biologique et syst?matique des Culicinae de l'Ile de La R?union. M?moires de l'Institut Scientifique de Madagascar 1953; 4 (S?rie E): 521-541.
11. Salvan M, Mouchet J. Aedes albopictus and Aedes aegypti at Ile de la Reunion. Ann Soc Belg Med Trop 1994; 74: 323-326(in French). MEDLINE
12. Ponlawat A, Harrington LC. Blood feeding patterns of Aedes aegypti and Aedes albopictus in Thailand. J Med Entomol 2005; 42: 844-849. MEDLINE
13. Reiter P, Gubler DJ. Surveillance and control of urban dengue vectors In: Gubler DJ, Kuno G, eds. Dengue and dengue hemorrhagic fever. Wallingford, UK: CABI Publishing, 1997: 1-22.
14. Gong P, Epton MJ, Fu G, et al. A dominant lethal genetic system for autocidal control of the Mediterranean fruitfly. Nat Biotechnol 2005; 23: 453-456. MEDLINE | CrossRef
15. Reiter P, Darsie R. Aedes albopictus in Memphis, Tennessee (USA): an achievement of modern transportation?. Mosquito News 1984; 44: 396-399.
16. Reiter P, Sprenger D. The used tire trade: a mechanism for the worldwide dispersal of container breeding mosquitoes. J Am Mosq Control Assoc 1987; 3: 494-501. MEDLINE
17. Gubler DJ. Dengue and dengue hemorrhagic fever: its history and resurgence as a global public health problem In: Gubler DJ, Kuno G, eds. Dengue and dengue hemorrhagic fever. Wallingford, UK: CABI Publishing, 1997: 425-462.
Back to top
<!--end simple-tail-->Affiliations
a. Institut Pasteur, Insectes et Maladies Infectieuses, Paris, France
b. Caracterisation et Controle des Populations de Vecteurs, UR016, Institut de Recherche pour le D?veloppement, Montpellier, France