Apr 4, 2008 (CIDRAP News) – Brazil's health ministry said this week that it has asked the military to help combat mosquitoes that spread dengue fever, as the number of sick patients with the disease grew to at least 55,000 so far this year.
Though dengue fever is common in Brazil, officials have said this year's outbreak is the worst in recent memory, averaging 1.4 new cases per minute, according to a report today from CNN.
The health ministry said dengue illnesses have killed 67 people this year in Brazil's Rio de Janiero state, and 58 other deaths are under investigation, CNN reported. Twenty-one people died from dengue hemorrhagic fever (DHF), the most severe form of the disease, and 14 fatalities were linked to dengue shock syndrome.
Dengue fever is a flu-like illness transmitted by certain Aedes mosquito species. Symptoms include headaches, rashes, cramps, and back and muscle pain. DHF is a potentially deadly complication characterized by high fever, bleeding, thrombocytopenia, increased vascular permeability, and, in particularly severe cases, circulatory failure. No effective treatment or preventive vaccine is available.
The virus occurs in four serotypes, and infection with any one induces immunity only to that serotype, according to the US Centers for Disease Control and Prevention (CDC). A second infection with a different serotype increases a person's risk for DHF.
Patients from outside the city of Rio de Janiero are flooding local hospitals, and about 400 patients a day are being treated at a military field hospital, the CNN report said.
"We have to go into this fight as if we are going into combat in order to minimize the population's suffering," Maj. Roberto Tury, a field hospital commander, told CNN.
Ali Kahn, a dengue expert at the CDC, told CNN that the number of countries reporting dengue infections has increased over the last 30 years, in part because of population growth.
A Mar 26 report from the Pan American Health Organization (PAHO) said the number of dengue hemorrhagic fever cases has increased significantly in several of Brazil's states compared with 2007, ranging from 2.2 times higher in Rio de Janiero state to 9.8 times higher in Amazonas state.
The PAHO report said the circulating serotypes are DEN 2 and DEN 3.
Health officials are seeing a change in the age distribution of severe dengue cases, the PAHO report said. Of 2,116 patients hospitalized with dengue fever in Rio de Janeiro state, 53% were children under age 14 years, and more than 50% of deaths have occurred in children between ages 2 and 13. "The number of deaths suggests a more severe evolution of clinical illness than expected," the PAHO reported.
Brazil's health ministry has sent 100 health professionals to assist federal hospitals in Rio de Janiero and 550 public health and emergency officials to help with community interventions, according to the PAHO report.
In January, federal health officials warned that the United States could be the next country to experience a dengue epidemic if the disease continues its aggressive expansion. One of the mosquitoes that serves as a vector for the spread of dengue—Aedes albopictus—was first seen in the United States in 1985 and has since spread to 36 states.
Dengue epidemics are already occurring in US tropical territories and commonwealths, and dengue fever is gaining a foothold in south Texas.
Though global experts aren't certain what factors are responsible for the rapid spread of dengue, theories include global urbanization, increased air travel, and climate change.
Mar 26 PAHO update on Brazil's dengue outbreak
Jan 10 CIDRAP News story "Federal officials warn of dengue threat to US"
Aug 9, 2007, CIDRAP News story "Dengue fever expanding its foothold in Texas"
CDC information on dengue fever and dengue hemorrhagic fever