Published Date: 2012-09-22 20:31:39
Subject: PRO/EDR> Dengue/DHF update 2012 (44): Americas
Archive Number: 20120922.1305323
DENGUE/DHF UPDATE 2012 (44): AMERICAS
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: 22 Sep 2012
In this update:
 Cayman Islands vector control
 Cases in various countries:
Mexico and Central America
Mexico, Iguala, Guerrero state.
Mexico, Jalisco state
Mexico, Morelos state, eastern region
Mexico, Puebla state
Mexico, Quintana Roo state
Mexico, Tamaulipas state
Mexico, Veracruz state
Central America, 4 countries
El Salvador, national
Honduras, Choluteca department
Panama, Panama City
Colombia, Huila department
Venezuela, Puerto la Cruz, Anzoategui state
Venezuela, Tachira state
Venezuela, Vargas state
Brazil, Nova Mutum, Mato Grosso State
Brazil, Aracaju, Sergippe state
 Cayman Islands vector control
Date: Mon 17 Sep 2012.
Source: Cay Compass [edited]
The Cayman Islands Mosquito Research and Control Unit and Oxitec have cited an 80 per cent reduction in the numbers of _Aedes aegypti_ mosquitoes in Grand Cayman after introducing genetically modified mosquitoes into the environment as a control measure. This finding, which was officially published in a report in Nature Biotechnology, was previously reported in the 17 Jan 2012 edition of the Caymanian Compass.
One of the main reasons the report said led to the Cayman Islands "having a need the need for alternative measures of control" was the high level of resistance to insecticide shown by _Aedes aegypti_ mosquitoes in Grand Cayman. The report references research done by MRCU Entomologist Angela Harris and Hilary Ranson of the Liverpool School of Tropical Medicine, who in their findings, "Pyrethroid Resistance in Aedes Aegypti," stated: "The Grand Cayman population of _Aedes aegypti_ is highly resistant to DDT and pyrethroid insecticides."
In an interview with the Caymanian Compass, Dr. Harris said, "For our experiments regarding the issue of resistance to insecticides we used mosquitoes that have been in a secure environment for over 30 years in a colony that was bred repeatedly over time and then compared those with the mosquitoes from the Grand Cayman. The results indicated that those found here are much more resistant and could be exposed to DDT for up to 8 hours."
Ms Harris added that the _Aedes aegypti_ mosquito has only been in the Cayman Islands since 2002 and could have likely acquired its resistance from its places of origin, which have not been determined. She also surmised that their resistance level could be as a result of cross-resistance from a pyrethroid resistance. In any event, much of Dr. Harris' research going forward will be to substantiate the theory that the mosquitoes came to the Cayman Islands with the resistance as opposed to developing it here. The Cayman Islands has never used DDT in its mosquito control efforts.
However, the Mosquito Research and Control Unit of the Cayman Islands was scrutinised in the foreign press for using genetically modified _Aedes aegypti_ mosquitoes to combat the spread of dengue fever. It was the 1st time the method was being used in a real world test area.
At the time, Bill Petrie, director of MRCU, said the initiative was essentially a new spin on an old technique in which males that were made sterile were released. He added that the difference here is that the male mosquitoes' genes were altered, as opposed to their sterility being chemically induced by radiation.
"MRCU along with Oxitec of Oxford University ran the trial for 6 months," Mr. Petrie said. "We chose a small isolated area in East End. This was done in 3 blocks; one block was where the method was introduced, while nothing was done in another block and the 3rd block was used to monitor the natural population of the _Aedes aegypti_ mosquito.
"Once the team perfected the technique, monitoring was done by traps. The final statistical analysis has shown a significant reduction in the population of this potential dengue carrier," he added.
Mr. Petrie said the male _Aedes aegypti_ mosquito cannot bite and lives a short life-span and since their eggs will not survive using this new method of control, the population of the species has decreased, as did the probability of dengue fever transmission.
Since the Cayman Islands' success using the genetic modification technique, several other jurisdictions are following suit.
"Dengue is a dangerous and debilitating disease, which affects up to 100 million people each year. The incidence of dengue has grown very rapidly in recent years: it is now a serious threat to global health, and the only means of prevention is to target the mosquitoes which carry it. We need new tools in the fight against these dangerous pests, and today's publication shows that Oxitec's approach can provide that," Mr. Petrie said.
[Byline: Stuart Wilson]
ProMED-mail from HealthMap Alerts
Harris AF, Nimmo D., McKemey AR, Kelly N, Scaife S, Donnelly CA, Beech C, Petrie WD, Alphey L. Field performance of engineered male mosquitoes. Nat Biotechnol 2011 Oct 30;29(11):1034-7.
[This is an interesting field experiment that produced an 80 per cent reduction in the _Aedes aegypti_ population through release of genetically modified mosquitoes into a population of native mosquitoes resistant to 2 common pesticides. The release of genetically modified mosquitoes will be considered controversial and opposed by some, but alternatives such as increasing use of pesticidal chemicals have been of limited success in medium- to long-term vector population reduction efforts. It will be interesting to see how successful the release of these genetically modified mosquitoes will be in other locations. An effective, commercially available dengue virus vaccine is still several years away. Meanwhile, vector control is the only way to prevent dengue virus transmission. - Mod.TY
A HealthMap/ProMED-mail map showing the location of the Cayman Islands in the Caribbean can be accessed at: http://healthmap.org/r/1IG3.]
 Cases in various countries:
Mexico and Central America
- Mexico, Iguala, Guerrero state. 20 Sep 2012. Dengue 800 cases; Decreasing, with 30-40 cases/week.
http://www.eluniversal.com.mx/estados/87832.html in Spanish.
Mexico [Maps of Mexico can be seen at
http://healthmap.org/r/1wvK. - Mod.TY]
- Mexico, Jalisco state. Dengue 129 cases; DHF 12 cases; Increasing.
http://www.milenio.com/cdb/doc/noticias2011/64346adc04d78af50bf575d54f368dd4 in Spanish.
- Mexico, Morelos state, eastern region. 17 Sep 2012. Dengue (conf.) 543 cases (susp.) 1159; DHF 142 cases; Municipalities: Cuautla 265 cases; Jojutla, 221 cases; Yautepec, 176 cases; Zacatepec 175 cases; Temixco 152 cases; Juitepec 86 cases; Cuernavaca 82 cases.; Increasing.
http://www.oem.com.mx/elsoldecuautla/notas/n2697770.htm in Spanish.
- Mexico, Puebla state. 16 Sep 2012. Dengue (1st week of Sep only) 192 cases; Increasing.
http://www.e-consulta.com/2012/index.php?option=com_zoo&view=item&layout=item&item_id=3337 in Spanish.
- Mexico, Quintana Roo state. 20 Sep 2012. Dengue 697 cases; Other municipalities: Othon P. Blanco 383 cases; Benito Juarez 177 cases; Increasing.
http://yucatanalamano.com/noticia/QuintanaRoo/Benito-Juarez-registra-177-casos-de-dengue.html in Spanish.
- Mexico, Tamaulipas state. 17 Sep 2012. Dengue 740 cases. Cities: Reynosa 200 cases; Altamira 229 cases; Tampico 204 cases; Increasing.
http://www.gaceta.mx/noticia.aspx?idnota=47177 in Spanish.
- Mexico, Veracruz state. 19 Sep 2012. Dengue (conf.) 5012 cases; (susp) 15 349 cases; DHF 1942 cases; Increasing.
http://www.imagendelgolfo.com.mx/resumen.php?id=342073 in Spanish.
- Central America, 4 countries. 21 Sep 2012. Dengue:
El Salvador (conf.) 8411 cases; Deaths 5; Dengue virus 1,2,3; Increasing
Costa Rica (conf.) 2246 cases; Dengue virus 1,2,3,4
Nicaragua (conf.) 1786 cases; Deaths 1; Dengue virus 1,2,3,4
Honduras Dengue (conf.) 1158 cases [must be underreported Mod.TY]; DHF 1154 cases; Deaths 1; Dengue virus 1,2,3,4
http://www.laprensagrafica.com/el-salvador/lodeldia/283598-el-salvador-pais-con-mas-dengue-de-c-a.htm in Spanish.
- Costa Rica. 18 Sep 2012. Dengue 8480 cases; DHF 9 cases. Increasing.
http://www.generaccion.com/noticia/167555/aumenta-casos-dengue-costa-rica in Spanish.
[The reason for the disparity with the case numbers given in the report above are not clear, but may confirmed versus suspected cases.
Costa Rica [Maps of Costa Rica can be accessed at
http://healthmap.org/r/1kdD. - Mod.TY]
- El Salvador, national. 19 Sep 2012. Dengue (conf.) 8411 cases; DHF 421; Deaths 5; San Salvador city 2434 cases. Increasing.
http://www.laprensagrafica.com/el-salvador/social/283341-detectan-911-casos-nuevos-de-dengue-en-el-salvador.html in Spanish.
[Maps of El Salvador can be accessed at
http://healthmap.org/r/1obh. - Mod.TY]
- Honduras, Choluteca department [state equivalent]. 18 Sep 2012. Dengue 220 cases; DHF (susp.) 12 cases; Increasing.
http://www.elheraldo.hn/Secciones-Principales/Regionales/Limpieza-general-en-Choluteca-para-prevenir-dengue in Spanish.
[Maps of Honduras can be accessed at
http://healthmap.org/r/1G7K. - Mod.TY]
- Panama, Panama city. 17 Sep 2012. Dengue (conf.) 41 cases (susp.) 172 cases; DHF 4 cases.
http://www.diaadia.com.pa/edicion/actual/impacto-interna.php?story_id=40773&edition_id=20120917 in Spanish.
[Maps of Panama can be accessed at
- Jamaica. 20 Sep 2012. Dengue (susp.) 560 cases; Increasing.
[A HealthMap/ProMED-mail interactive map showing the location of Jamaica can be accessed at http://healthmap.org/r/00Vh. - Mod.TY]
- Colombia, Huila department [state equivalent]. Deaths 7; Municipalities: Garzon 403 cases; Aipe 289 cases; Rivera 158 cases; Palermo 289 cases. Decreasing.
http://www.diariodelhuila.com/site/index.php/menu-actualidad/25916-continua-brote-de-dengue-en-seis-municipios-del-huila- in Spanish.
[Maps of Colombia can be accessed at
http://healthmap.org/r/3gvP. - Mod.TY]
- Venezuela, Puerto la Cruz, Anzoategui state. 17 Sep 2012. Dengue 336 cases; DHF 8 cases.
http://eltiempo.com.ve/locales/puertocruz/salud/clinica-de-sotillo-ha-recibido-336-casos-de-dengue-este-ano/65249 in Spanish.
[A HealthMap/ProMED-mail interactive map of Venezuela can be accessed at
http://healthmap.org/r/3buv. - Mod.TY]
- Venezuela, Tachira state. 18 Sep 2012. Dengue 564 cases; DHF 44 cases.
http://www.entornointeligente.com/articulo/1314311/VENEZUELA-Casos-de-dengue-aumentan-285-en-el-estado-Tachira-18092012 in Spanish.
- Venezuela, Vargas state. 21 Sep 2012. Dengue (conf.) 131 cases; Declining.
http://www.el-nacional.com/regiones/Disminuyen-casos-dengue-Vargas_0_49195129.html in Spanish.
- Bolivia. 19 Sep 2012. Dengue (conf.) 6200 cases; Deaths 37.
http://saludable.infobae.com/lanzaron-la-campana-2012-de-prevencion-del-dengue/ in Spanish.
- Brazil, Nova Mutum, Mato Grosso State. 17 Sep 2012. Dengue (conf.) 191 cases (susp.) 26 cases; DHF 4 cases.
http://www.sonoticias.com.br/noticias/11/160397/mutirao-de-limpeza-da-dengue-comeca-em-2-bairros-de-nova-mutum in Portuguese.
[Maps of Brazil can be seen at
http://healthmap.org/r/1zJi. - Mod.TY]
- Brazil, Aracaju, Sergippe state. 19 Sep 2012. Dengue 1869 cases; DHF 13 cases; Declining.
http://www.infonet.com.br/saude/ler.asp?id=133976 in Portuguese.