Thursday, May 22, 2008

Yellow fever in Central African Republic

The WHO EPR Disease Outbreak News and ProMedMail reported 2 laboratory confirmed cases of yellow fever on the 15th May 2008 in Bozoum sub-prefecture, Ouham-Pende Prefecture of the Central African Republic. The Ministry of Health initiated an epidemiological investigation, and requested 64 931 doses of yellow fever vaccine from the Global Emergency Stockpile of Yellow Fever Vaccine, which is funded by the GAVI Alliance. The target population in the Bozoum sub-prefecture was estimated to be 55 035 people, which the Ministry of Health plans to vaccinate during a 3-day campaign starting on the 26th May. Mod. CP in the ProMedMail report notes that it would be important to know whether the 2 laboratory confirmed cases were isolated cases or potentially represent the start of an urban epidemic.
Hopefully the global emergency stockpile which was depleted in February following mass immunizations in South America have been adequately replenished to be able to provide supplies.

Monday, May 19, 2008

First case of West Nile fever in Texas in 2008

The first case of West Nile Fever in 2008 has been reported in Texas, Montgomery County, according to ProMedMail and the Houston Chronicle. The report states that although West Nile season typically starts in the summer, with mid-August through
mid-September being peak months because they're the hottest and driest months, it is not unusual to see cases as early as March and as late as December. However, one wonders how many cases of asymptomatic or mild West Nile infections must have been already gone unreported in the same area, given that 80% of infected people do not have any symptoms, and whether this early start signals an increased West Nile activity for Texas this year. Last year, Texas reported 170 neuroinvasive and 90 fever cases, and 17 deaths, according to state health records. The Centers for Disease Control and Prevention map of West Nile virus activity (as of 6 May 2008;  http://www.cdc.gov/ncidod/dvbid/westnile/Mapsactivity/surv&control08Maps.htm) as well as ArboNet shows that 2 human cases have been reported in Mississippi, one in Arizona, and one in Tennessee.

Friday, May 16, 2008

News focus on Aedes albopictus in current issue of Science

There is an excellent News Focus article on the global spread of Aedes albopictus  by Martin Enserink in the current issue of Science. The article gives the historical background of the spread of this mosquito, and highlights its potential public health consequences. Admirably, a clear distinction is made in regards to Aedes aegypti, the yellow fever mosquito. It's very interesting to see the differences in the judgment of different experts (notably Duane Gubler and Didier Fontanille) in terms of the level of risk attributed to Aedes albopictus. One aspect that I was lacking from this article was raising the possibility of a chikungunya outbreak in the South-Eastern United States. Nonetheless, this article is an excellent read and is highly recommended for anyone interested in mosquitoes and the diseases they spread.


Thursday, May 15, 2008

Predictive study for Ross River Virus infections in the Darwin area of Australia published

Susan P Jacups of Charles Darwin University, Darwin, Australia publishes an elegant study in the upcoming issue of Tropical Medicine and International Health about predictive indicators for Ross River virus infection in the Darwin area of tropical North-Eastern Australia. Ross River virus is an Alphavirus, a close relative of chikungunya and Barmah Forest Virus, causing  similar symptoms of fever, joint pain and rash. The study is based on the statistical analysis of laboratory confirmed cases of RRV infection between 1991 and 2006 as well as climatic, tidal and mosquito data collected from 11 trap sites weekly in the study area. The authors identified the best predictors of RRV infections using three multivariate Poisson models. The best global model included rainfall, minimum temperature and the average monthly trap numbers of three implicated mosquito species populations (Culex annulirostris, Aedes vigilax, Aedes notoscriptus), and explained 63.5% of the deviance while predicting disease accurately. The model also indicated that predicted anthropogenic global climatic changes may increase RRV infections. My favourite point is that the predictors in the global model, since they all have a lag time of either 1 or 3 months, can be used as an early-warning system for potential RRV outbreaks. Such location-specific early-warning systems are badly needed for other vector-borne diseases, such as e.g. West Nile, dengue and chikungunya.


Wednesday, May 14, 2008

Dengue epidemic raging on in Rio de Janeiro

This years dengue epidemic is raging on in Rio de Janiero, with 76,385 cases reported in the city alone until 9th May this year, according to ProMedMail (see also here). In the whole state of Rio, 134,643 cases have been reported so far. In the state of Rio, 106 deaths occured due to dengue, with 3 additional cases between 4th and 10th May. 64 of these deaths occured in Rio de Janeiro.

At the same time, the governor of the state Rio Grande do Norte declared a state of emergency due to the 19,157 dengue cases, 78 DHF cases and 2 deaths reported until 3rd May this year in 154 cities in the state.


Wednesday, May 7, 2008

New issue of the American Journal of Tropical Medicine and Hygiene available

The 2008 May issue of the American Journal of Tropical Medicine and Hygiene is now available.
Particular papers of interest (to me) are:


Management of Travelers with Fever and Exanthema, Notably Dengue and Chikungunya Infections
Patrick Hochedez, Ana Canestri, Amélie Guihot, Ségolène Brichler, François Bricaire, AND Eric Caumes
Am J Trop Med Hyg 2008;78 710-713
http://www.ajtmh.org/cgi/content/abstract/78/5/710


Evaluation of Mosquito Densoviruses for Controlling Aedes aegypti (Diptera: Culicidae): Variation in Efficiency due to Virus Strain and Geographic Origin of Mosquitoes
Supanee Hirunkanokpun, Jonathan O. Carlson, AND Pattamaporn Kittayapong
Am J Trop Med Hyg 2008;78 784-790
http://www.ajtmh.org/cgi/content/abstract/78/5/784

Experimental West Nile Virus Infection in Jungle Crows (Corvus macrorhynchos)
Hiroaki Shirafuji, Katsushi Kanehira, Masanori Kubo, Tomoyuki Shibahara, AND Tsugihiko Kamio
Am J Trop Med Hyg 2008;78 838-842
http://www.ajtmh.org/cgi/content/abstract/78/5/838

Yellow fever in Peru and Ecuador

Two cases of sylvan yellow fever have been reported between 20-26 April 2008 in Peru, according to ProMedMail, based on the Epidemiological Bulletin of the Ministry of Health of Peru. The 1st case was a 23-year-old unvaccinated man from the Loreto department, while the 2nd case is a 21-year-old man of unknown vaccination status from Tocache Nuevo (Tocache district and province), San Martin department. He became ill between 6-12 Apr 2008. Since the beginning of 2008, there were 13 reported yellow fever cases in Peru, including 3 confirmed mortalities, 6 probable, and 4 discarded cases. Mod TY of ProMedMail asserts that from a public health point of view, it is fortunate that the reported sylvan yellow fever cases didn't spread into a major urban yellow fever outbreak.

Also, the CDC updated its yellow fever risk map for Ecaudor, following the recommendation of the Ecaudor Ministry of Health of yellow fever vaccination for all travelers to the following provinces in the Amazon Basin: Morona-Santiago, Napo, Orellana, Pastaza,
Sucumbios, and Zamora-Chinchipe.  This is in addition to the current recommendation for yellow fever vaccination for travelers going to areas along the eastern slopes and to the east of the Andes Mountains. At present, yellow fever vaccination is only required for travelers entering Ecuador if they are greater than one year of age and if they are coming from a country in the yellow fever endemic zone.