It’s a buzzing menace that may have caused you many sleepless summer nights. Weighing not more than two milligrams, the females of the species can’t pursue their human prey any faster than a mile an hour. Still, her sting is lethal enough to make you itch for hours. And, if she is infected with a virus, you are in for trouble. Doctors worldwide say the lowly mosquito is by far one of the most dangerous insects we are yet to find a way to get rid of. Mosquito bites have infected millions all over the world with potentially lethal diseases such as malaria, dengue and chikungunya.
Malaria has been a scourge all through history and has killed more people than wars and plagues combined. Even Charak Samhita, India’s ancient medical literature, mentions it. It claims more children worldwide than any other infectious disease. But even today, despite the millions spent on research, there is no vaccine against it. At best, there are only preventable drugs.
Malaria has today become endemic to 106 countries. Such is the severity of the problem that India is now going back to using the banned DDT in a desperate attempt to fight the disease.
Still, everybody realizes the enormity of the task, at least in India, considering the low levels of sanitation, cesspools, open gutters, poor sewage and drainage systems, and inadequate wetland management.
And now health professionals are waking up to another dangerous reality: the resistance of the parasite to drugs. The parasites reproduce so quickly that they are constantly spinning out new mutations, some of which protect the parasites from chloroquine, the most commonly administered drug for the infection.
Says Girish Chandra Vaishnava, director, internal medicine, Fortis Hospital, New Delhi: “We are increasingly treating patients suffering from drug-resistant strains of the disease. There are new complications every day despite the national malaria eradication programme.”
Types of malaria
Malaria is caused by a parasite called plasmodium, which is transmitted when an infected female mosquito bites and transfers it through its saliva. Inside the human body, the parasites multiply in the liver, and then infect red blood cells. Symptoms of the disease include fever, headache, and vomiting, and these usually appear between 10-15 days after the bite. If not treated on time, the parasites can disrupt blood supply to vital organs and become life-threatening.
There are four types of human malaria—plasmodium falciparum, plasmodium vivax, plasmodium malariae and plasmodium ovale. Of these, falciparum, by far the most deadly type of infection, and vivax are the most common.
Caused by the plasmodium falciparum virus, it is an acute form of malaria that affects the brain and is accompanied by high fever. Malignant in nature, it can also affect the liver, intestines, kidneys and destroy the red blood cells.
Doctors suggest that if the patient is not treated within 24-72 hours, it could be fatal. Symptoms include impaired consciousness, delirium, abnormal neurological signs, convulsions and high fever. Doctors also say that it is important to determine the causes of the convulsions in cerebral malaria: They say it could be because of the severe falciparum infection, high fever and even the anti-malarial drugs used.
In children, high fevers can also cause convulsions and psychosis. However, these subside with the decrease in the body temperature.
Many antimalarial drugs such as chloroquine and quinine can also cause altered behaviour, convulsions, hallucinations and even psychosis. Therefore, these should be prescribed only after a conclusive diagnosis. What makes the problem more acute is the fact that the virus is now fast building resistance to chloroquine.
High fever, severe headache, pain behind the eyes and in muscles are some of the most common symptoms. Patients can also suffer from nausea, vomiting, bitter taste that reduces appetite, rashes and red skin. What makes the situation even more serious is the fact that there is no specific medicine to treat it and doctors just give supportive treatment. However, if the platelet count goes low, it can become life-threatening. It could also lead to complications like lung infection or a collapse of the circulatory system where the blood flow is affected. Also, if the blood pressure level falls, the patient can go into a state of shock.
Dengue patients have to be kept hydrated as the body loses fluid because of fever. Doctors suggest that patients should be given lot of water as hydration helps to build up the platelet level. Says Ashutosh Shukla, consultant and head of department, internal medicine, Artemis Health Institute, Gurgaon: “Despite the absence of a specific drug to treat dengue, it can be easily treated and managed.”
According to the World Health Organization, epidemics that closely resemble chikungunya as we know it today, were first recorded in India in 1824. But in recent times, there have been 1.25 million cases reported in 151 districts across India. The worst affected states were Karnataka and Maharashtra.
A viral disease spread byinfected mosquitoes, chikungunya is not life-threatening. However, it can cause fever, headaches, skin rashes and multiple joint pains that can linger for months. In severe cases, patients can also develop deformed joints that could be permanent.
Malaria is diagnosed by the clinical symptoms and microscopic examination of the blood. It can normally be cured by anti-malarial drugs, and the symptoms—fever, shivering, pain in the joints and headache—quickly disappear once the parasite is killed.
Chloroquine is the standard medicine used to treat malaria, but certain strains have developed resistance to the drug. However, more expensive drugs like Artesunate, Artemether and Artether too are available. The parasites haven’t yet developed resistance to these.
Says Ajay Rastogi, consultant, internal medicine, Fortis Hospital, Noida: “While treating mosquito borne diseases, the challenge is in dealing with new resistant strains that come up every year. That is why constant research on new drugs is very crucial to successfully contain the infection.”
Adds Dr Vaishnava: “Malaria is very difficult to prevent. At best, you can take precautions. However, this is easier said than done, as mosquitoes are everywhere. One way to keep dengue away is to try and see that a mosquito does not bite you between 4pm and 7pm. Female mosquitoes bite only between these times. They don’t attack in the morning or at night. The mosquito survives in clear water and so it is important to see that any water that has collected after the rains is not left stagnant.”
A number of mosquito repellents are available in the market—such as coils, vaporizing mats, liquid vaporizers, aerosols and creams—that can help keep the insects away. However, doctors warn of possible allergies from prolonged exposure to these.
A recent survey of nine Indian states, involving 5,920 respondents, by the Malaria Research Centre, New Delhi, revealed that mosquito repellents posed health hazards. Users complained of a variety of acute toxicity effects, such as eye and bronchial irritation, headache, skin rashes, cough, cold, pain in the ear and throat et cetera either soon after or within a few hours of using the repellents. A 1998 report by the Indian Toxicological Research Centre in Lucknow also pointed to serious health consequences from using repellents.
Malariologist Ved Prakash Sharma, from the Indian Council of Medical Research, who led the study, warns that use of repellents for long periods may lead to neurotoxic and immunotoxic hazards. In fact, some studies have also reported corneal and liver damage following prolonged use.
Dr Shukla has another word of caution in the treatment of dengue. “All of us have a platelet count of 1.5-4 lakh. It is necessary to start platelet transfusion only if it falls below 30,000. But many doctors create unnecessary panic, saying that it needs to be done when it is not really required. Sometimes, certain medicines cause the drop in the count. One should avoid antibiotics as it has no role in dengue—the causative organism is a virus. Medicines such as Brufen and Combiflam that are randomly prescribed to fight pain and the fever, should not be given either as they reduce the platelet levels.”
Adds Dr Vaishnava: “There is no easy solution to eradicating mosquitoes. We should not expect the government to do everything. We have to keep our surroundings clean. Community participation in every residential area is crucial for this. Mosquitoes just should not be allowed to breed.”
Typical features: There are three stages of malaria: the cold, hot and the sweating stage. It starts with shaking chills, usually at mid-day, and lasts from 15 minutes to one hour (cold stage), followed by high-grade fever, which could last between two and six hours (hot stage). This is followed by profuse sweating and the fever gradually subsides. The fever is usually accompanied by headaches, vomiting, delirium, anxiety and restlessness.
Atypical features: These manifestations occur in those infected by the falciparum virus, children and old people, and pregnant women, among others.
Headache: It could be accompanied with or without fever.
Bodyache, backache and joint pains
Altered behaviour, psychosis
Vomiting and diarrhoea
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