November issue 2006
The Aedes Factor
A mosquito has the nation in panic. And for good reason. Mosquitoes, often considered the scourge of the world, are transmitters of some of the world’s deadliest diseases, such as malaria and yellow fever.
The mosquito making headlines in Pakistan these days, is a little black and white mosquito, known as Aedes aegypti. Across the country, people have become armchair experts, overnight entomologists, well-versed in its characteristics and habits. Photos in the press have familiarised citizens with the insect’s tiny body and white markings. For it is her, the female Aedes, to whom we owe no thanks for the country’s lastest health crisis: dengue fever.
Dengue fever is, however, nothing new to Pakistan. Outbreaks of the tropical virus, including its more deadly form, dengue haemorrhagic fever (DHF), have spread through Pakistan in previous years. Just last year Pakistan experienced an outbreak. A surveillance study done during July to October 2005 at CHK and Lyari General Hospital screened 350 kids suffering from less than seven days of fever. Four were found to be dengue positive and 11 children were deemed indeterminate.
According to Dr Tasneem Ahsan, head of medicine at the Jinnah Post Graduate Center (JPMC) in Karachi, last year’s dengue outbreak occured during the same time last year, but not to the same extent. “This time it has been much worse with sporadic cases witnessed even before the monsoon in July, but it peaked around August,” she claims. “We started sending the cases for dengue-testing to the National Institute for Health (NIH) in Islamabad when we found six consecutive cases — out of which one patient died.”
Although local doctors raised the alarm around that time, concerns were dismissed on the official level as “a phobia.” But then the cases started escalating. “These days, anybody with high-grade fever, chills and other symptoms is assumed to be a dengue patient unless proven otherwise,” says Ahsan.
Professor D.S. Akram, head of the paediatric department at Civil Hospital in Karachi, says that an outbreak of DHF was also reported in Karachi in 1994. But the presence of dengue fever was found in children in studies done by her as far back as 1980.
The bottom line? Dengue is not foreign to our shores. In fact, the World Health Organisation (WHO) classifies dengue as endemic in Pakistan.
Being endemic means that the disease occurs continuously and with predictable regularity within a specific area or population. According to recent statistics, a total of 2,917 suspected cases of dengue fever have so far been reported in hospitals across the country. Of these, 1,066 cases have been confirmed as dengue positive. Thirty-three patients have succumbed to the disease.
The basic type of dengue, the non-haemorrhagic form, is not typically fatal. It is the haemorrhagic form, which leads to various degrees of internal bleeding, that can be fatal. But the incidence of mortality is not high. Only five per cent of those infected with DHF die. So while 33 deaths is tragic, it is not out of whack with international dengue-associated casualty rates. The majority of cases have been reported in the seaside city of Karachi: over 1,700 suspected and over 500 positive cases.
How do we stop the virus from becoming worse? What do we need to do to stop dengue from reaching undisputable epidemic proportions?
Part of the answer seems to lie in water.
Water is the source of life. This is the same for mosquitoes as it is for humans. So, it is not surprising that rates of dengue infection peaked in August. After Karachi’s two heavy monsoon rainfalls, the city was flooded — there were literally thousands of stagnant pools of water splashed across the city. Still water is the mosquito’s breeding ground.
Because dengue haemorrhagic fever is caused by a virus for which there is no known cure or vaccine, the only treatment is to treat the symptoms. This, of course, is reactionary. According to the WHO country representative in Pakistan, Dr Khalif Bile Mohamud, preventive measures, including improved sanitation conditions, are the only answers to this global phenomenon. “We need to intensify the public cleanliness campaign to stop mosquitoes from breeding and carry out fumigation and fogging to eliminate mosquitoes and their breeding grounds,” he said. He remarked that unless the solid waste removal system in urban areas was improved, there was hardly any chance of success in eliminating the habitat of mosquitoes. “Moreover, we need to ensure effective surveillance, monitoring and diagnosis facilities and ensure proper netting of infected patients during their hospitals stays and recovery period,” he said, emphasizing the need for more effective and sustainable vector control measures during the main dengue transmission season.
The stress these days is on dengue-testing. Tasneem Ahsan from JPMC explains that this test measures the specific antibody that develops in response to infection from the dengue virus. “However, the body requires time to make that antibody and normally you need two tests to definitively establish its presence: one in the beginning and the other about a fortnight later.” The second test establishes that there has been a marked alteration in the state of the antibody. “But by then, two weeks later, most dengue patients are better. Or, in rare cases, dead,” says Ahsan. “I think all this hype about free dengue tests and kits is pretty much useless.”
She does admit, however, that testing has its merits. When hospitals were getting a spate of cases and didn’t know what to diagnose, it was initially useful. Dengue symptoms, including fever, headache, muscle aches, joint aches, decreased appetite and nausea, are similar to symptoms in dozens of other illnesses, such as forms of malaria, severe septicimia, or even the Congo virus, which is the first concern of patient care-givers. “The Congo virus spreads through contact with an infected person’s fluid, unlike dengue, which only spreads via a mosquito bite,” explains Ahsan. “That is the reason that, generally, there are always deaths of medical care-givers tending to hospitalised Congo virus patients. When these cases first started pouring into the hospital, we didn’t know what it was, and so there was a concern about the epidemiology of the symptoms because they overlap in a variety of diseases. But the thrust of the movement should be on sanitisation.”
Further, some collected data is also casting doubt on some dengue fever accepted facts. According to Dr Seemin Jamali, who heads the accident and emergency department at JPMC, compiled data on affected patients shows that 23 per cent of the 238 patients seen at the hospital were females, while the other 77 per cent were males. This puts a question mark on the belief that homes are the greatest places of risk.
Some say hope is around the corner, though. And it comes in the form of a ‘papaya leaf miracle cure.’ But doctors have little knowledge of the much publicised reports that have been circulating on the Internet and in the city of Karachi. According to one news report, Dr Sumedha Bajaj of Bombay Hospital, says that two tablespoons of papaya leaf juice, extracted from the fruit’s raw leaves, taken only once a day, is a quick and easy dengue cure. However, Dr Bajaj seems to reference only one instance where a patient rebounded — in three quick days nonetheless — after taking the tropical fruit remedy. And just a quick scan of the web shows that every reference to this miracle cure is to the same patient, with almost no other doctors stepping in to back Dr Bajaj’s claim.
Around the world, the emphasis for dengue prevention is on a sustainable, community-based integrated mosquito control programme, with limited reliance on insecticides. Preventing epidemic disease requires a coordinated community effort to increase awareness about dengue/DHF, how to recognise it, and how to control the mosquito that transmits it. The easiest way to eliminate potential breeding grounds is to take care of standing water. Items that collect rainwater, or those that are used to store water, should be covered or properly discarded. Pet and animal watering containers and vases with fresh flowers should be emptied and scoured regularly. This will eliminate the mosquito eggs and larvae and reduce the number of mosquitoes present in these areas.
Also, doctors advise use of personal protection such as full-length clothing (no exposed arms or legs), netting, mosquito repellent containing DEET, and if possible, travelling during periods of minimal mosquito activity.