Members of the Infectious Diseases Society of Pakistan (IDSP) note with concern the rising number of cases of dengue viral fever and viral hemorrhagic fever in the city, and wish to offer explanations regarding the outbreak.
Viral hemorrhagic fever is a serious infection caused by several viruses around the world. In Pakistan we presently have two of these viruses: Congo-Crimean viral fever (CCVF) and Dengue hemorrhagic fever (DHF).
CCVF is spread by the bite of a tick that resides in the skin of cattle. In 1970s there was an outbreak in Quetta that killed unsuspecting surgeons and paramedics operating on patients with fever and bleeding from the stomach. CCVF is endemic in parts of Baluchistan and Afghanistan and we see it from time to time in small outbreaks in Karachi. It is a serious illness with more than 50% death rate from bleeding from the gums, nose, stomach, lungs and the skin. Its danger is in spread from person to person through infected blood and body secretions.
Dengue virus, on the other hand is spread by the bite of a mosquito (Aedes aegyptii). In 1994 there was an outbreak of dengue fever in Karachi. It was a mild form then that caused fever, muscle pain and a rash with low white blood cell and platelet counts. Although it produced discomfort, the illness was completely reversible and self-limiting. Unfortunately, an attack of dengue fever does not always produce complete immunity. A second attack may be more severe and can result in bleeding from multiple body sites. It was predictable at that time that a second attack with the same virus would cause hemorrhagic fever. And indeed, Dengue hemorrhagic fever (DHF) is also upon us now.
Clinicians are reporting dengue fever since early August with increasing numbers in successive months. Majority of cases are still mild and reversible, but a few are presenting with very low platelets and bleeding. An occasional case may be dengue shock syndrome (DSS) and prove fatal.
CCVF and severe DHF appear to be similar and can be differentiated only by serological blood tests. Unfortunately these tests are expensive and not always accurate. Molecular tests are more sensitive but not available to us. Hence, what is often reported as CCVF may actually be a severe form of DHF. CCVF requires antiviral treatment and isolation to protect contacts. DHF, on the other hand does not require isolation as it spreads by mosquito bite and does not require antiviral drugs. In absence of accurate tests it is wise to protect all contacts.
CCVF and DHF are serious public health problems as a result of unhygienic surroundings and practices. Garbage and sewage invite stray animals, ticks, flies and mosquitoes; only a few private hospitals have an infection control department or policies; public diagnostic labs. do not offer sophisticated tests and private labs are beyond range.
Without diagnosis there are no statistics.
The IDSP offers the following observations and suggestions:
1)
There is an increasing number of cases of dengue viral fever which usually resolve without treatment. An occasional case may become hemorrhagic, but the infection is not transmissible person to person. Dengue will probably subside in a few weeks till the next mosquito breeding season. CCVF is certainly much less common and is sudden and severe in onset.
2)
DVF should be managed with re-hydration and fever management. Observation for bleeding with severe thrombocytopenia are essential.
3)
Civic authorities and private individuals should co-operate towards keeping the city clean. An immediate and intense operation of mosquito control must be put into action. Sheep or cattle must not be kept or slaughtered in or near the premises.
4)
For individuals our advice is to avoid getting bitten by mosquitoes by all possible means, using insect repellants, window mesh, bed nets, and cleaning up gardens and neighborhoods of stagnant water or garbage dumps.
5)
Every private or public hospital must establish standard practices of infection control. There are set practice guidelines, and the IDSP is always willing to share its expertise and conduct workshops.
6)
Federal public health laboratory of National Institute of Health (NIH) Islamabad must facilitate diagnosis by both serology and molecular biology.
Members Infectious Disease Society of Pakistan Karachi November 29, 2005
Dr. Naseem Salahuddin Dr. Afia Zafar Dr. Anita Zaidi Dr. Altaf Ahmed Dr. Farheen Ali Dr. Rumina Hasan
Total Number
of Visitors
2440 since August 2003
Official website of Infectious Diseases Society of Pakistan.
Site designed & maintained by Sibex
Systems
