The government of Paraguay declared a 60-day state of emergency on March 1 due to a rapid increase of dengue fever cases.
Although most of the 14,654 dengue fever cases in Paraguay have not been deadly, 40 people have developed the severe hemorrhagic form of dengue fever, which some Paraguayan physicians are calling gastric dengue. This form of dengue fever has resulted in four deaths; there have been 10 deaths overall, including one public health official.
The hemorrhagic variant of dengue fever causes internal bleeding due to the collapse of blood vessels, liver enlargement and circulatory failure. This type of dengue fever attacks vital organs and kills between 1% and 20% of those infected.
Health officials said increases of rain and overall warmer weather may possibly be contributing to the outbreak.
Other countries affected
Paraguay is not the only country to experience a dramatic increase of dengue fever cases. In Peru, nearly 400 cases have been reported so far this year; two of them were fatal. Brazil has reported 53,146 dengue fever cases this year, with 300,000 cases in 2006. Mexico reported 22,810 dengue cases in 2006, an increase from 17,487 in 2005. Argentina reported 13 cases of dengue fever in the Formosa province, located north of Buenos Aires, which borders Paraguay. There were 397 suspected cases in Bolivia as of Feb. 7, up from 270 cases reported on Feb. 2. The majority of the cases were reported in Santa Cruz and Montero. Panama reported two fatalities due to hemorrhagic dengue fever in December 2006.
Countries in other parts of the world are at risk for developing a dengue fever outbreak as well. According to Trinh Quan Huanas, Vietnamese Deputy Minister of Health, Vietnam could experience an outbreak if preventive measures are not taken. In 2006, Vietnam reported more than 77,800 cases with 68 fatalities, up from 49,400 cases with 51 fatalities in 2005.
Dengue fever deaths in Indonesia reached 380 as of Feb. 27 out of the 27,000 infected people since January. Between February 2006 and January 2007, there were 33,804 reported cases with 356 fatalities.
Dengue fever re-emergence
A female Aedes aegypti mosquito acquiring a blood meal from her human host.
Source: CDC/Frank Hadley Collins
Dengue fever cases in the Americas have been increasing for the last 25 years, and recent increases are just part of this overall trend, Lyle Petersen, MD, MPH, director of the CDCs division of vector-borne infectious diseases in Fort Collins, Colo., said in an interview. The increase is due to a number of factors, including the resurgence in the Americas of the Aedes aegypti mosquito, the principal vector of dengue.
According to Petersen, the Aedes aegypti mosquito was close to eradication in the Americas in the early 1970s due to control measures, such as cleanup campaigns, to eliminate breeding sites and application of residual pesticides like DDT. Eventually, the campaigns and DDT were phased out leading to more and more cases of dengue fever.
Since the 1970s, container societies have developed in which ubiquitous plastic buckets, used tires and a myriad of other outdoor disposed objects breed mosquitoes. This development has made it nearly impossible to eliminate a sufficient number of breeding sites to lower the density of Aedes aegypti to stop dengue transmission, particularly in large urban environments, Petersen said.
Uncontrolled urbanization has also produced deterioration of drinking water, sewer water and wastewater management systems, which has also increased mosquito breeding, according to Petersen.
According to Paraguay opposition spokesperson, Anibal Carrillo, MD, the number of cases could be multiplied tenfold. Carrillo said dengue fever cases sometimes go unreported because many Paraguayans cannot afford to see a physician. If people have dengue fever, they sometimes do not seek medical treatment if it is of a milder type.
People who do seek medical care are often diagnosed clinically in outpatient settings and are not confirmed by laboratory tests. Even if the diagnosis is confirmed, outpatient diseases are often underreported. Also, dengue can be confused with other febrile diseases, which is why so many cases go underreported, Petersen said.
To reduce risk of dengue fever, Petersen suggests using repellents containing DEET; however, this is not practical for long-term residents. Prevention of mosquitoes entering households, such as use of window screens and air conditioning, can reduce this risk. Unfortunately, these measures are often not practical in many tropical settings, Petersen said.
WHO officials estimated that more than 2.5 billion people worldwide are at risk for contracting dengue fever this year. – by Pam Rothman
For more information:
- Visit the CDCs Web site for more information about dengue fever at www.cdc.gov.