A 101 guide on the mosquito menace

Until six-seven years back if mosquitos were breeding unchecked in your area, chances were that people would be afflicted by malaria. But lately, “particularly this year, I have seen only some sporadic cases of malaria. Dengue and chikungunya have become bigger scares”, says Rahul Pandit, intensivist, Fortis Hospital, Mulund, Mumbai. Navneet Kaur, senior consultant, internal medicine, Nova Specialty Surgery, Delhi, agrees: “Since the beginning of September there has been a sudden increase in the number of people I see every day in my OPD (out-patient department) with suspected dengue. Of the 20-odd patients I see with characteristic symptoms, at least 50% are testing positive with NS1 antigen (dengue virus). Whenever there is temperature change, these mosquitoes breed and the cases increase. The problem should ease off from mid-October (as both the vector, the mosquito, and the virus cannot survive in the cold).”

Although many of us have enough immunity to fight the dengue virus, often children, between the ages of 6 and 15, are most susceptible. “They tend to get bitten early in the mornings when they head for school and are usually outdoors. Plus, those with compromised immunity, like infants, old people and pregnant women, may also be at risk,” adds Dr Kaur.

According to Dr Kaur, one reason malaria cases seems to have not grown in urban areas is that sanitation situation has improved (malaria-carrying mosquitoes breed in dirty water). Dengue and chikungunya virus-carrying mosquitos breed in stagnant, clean water too, hence increasing their population and thereby leading to a large number of people being afflicted by these two ailments. “An important point to remember is that an attack of any mosquito-bred illness does not make one immune to a repeat attack (as the body does not develop
immunity against them) and a repeat attack usually comes with more complications,” adds Dr Pandit.

The difference among the three

Malaria is a protozoan infection, whereas dengue and chikungunya are viral infections. “Malaria is caused by two different types of protozoan parasites—vivax and falciparum (vivax is more common in India),” says Rommel Tickoo, consultant, internal medicine, Max Super Speciality Hospital, Delhi. There are four distinct strains (types of viruses) of dengue: Den-1, Den-2, Den-3, Den-4. “The dominant strain this year (all over India) is Den-2 (last year it was Den-1), which causes severe symptoms and longer hospitalization,” says Dr Kaur.

Most often the initial symptoms of malaria, dengue and chikungunya are quite similar and often overlapping: High fever (for two-five days) with body ache, abdominal cramps, pain behind the eyes, loss of appetite, nausea and vomiting. “The only distinguishing factor is that in case of malaria usually (but not always) there is intermittent fever with characteristic chills, and with chikungunya the joint pains are way too intense,” explains Dr Tickoo.

Dengue usually has three stages: Plain fever, which is the least problematic (fever, pains, etc.) comes first, and next is hemorrhagic fever, where hemoconcentration happens (haemoglobin levels elevate leading to plasma leakage so often fluid comes into the abdomen and lungs). “Here, regular hydration is extremely critical, which if not maintained may lead to dengue shock syndrome, leading to severe dehydration, drop in blood pressure and metabolic acidosis (blood becomes acidic). If this stage is not handled properly, it can be fatal, as there is risk of multiple organ failure (lungs, liver, kidneys),” says Dr Tickoo.

In dengue, fever usually subsides after five days. That’s when the patient starts feeling good and thinks he is getting better. “This, in fact, is the most critical time. Around this time the immunity is really low and we see a sudden drop in the platelet count, the body temperature often goes very low (may hover around 96 degrees Fahrenheit) and blood pressure drops. Rashes too begin appearing on the body and chances of internal bleeding increase,” says Dr Tickoo. While chikungunya is considered the least dangerous of the three, its after-effects last the longest with joint pains staying up to a minimum of six months (often for a year too).

Finding out which one it is

The malaria antigen test is extremely accurate but must be done before one takes any antimalarial drug, ideally on the first or second day of the symptoms. The dengue NS1 antigen test gives accurate results till five-seven days (from the onset of the symptoms). And as the body develops IgM (Immunoglobulin M) antibodies as a response to dengue virus, from Day 4 or Day 5, dengue-specific IgM and IgG (Immunoglobulin G) tests can be done (till two weeks) to diagnose dengue. “One must understand that platelet counts is not a diagnostic test; it is just done as an aid to treatment (to decide when transfusion is needed),” says Dr Pandit. “The chikungunya antigen test is effective in the first few days and gets difficult to catch later, so usually a clinical (symptomatic) diagnosis is done for it,” says Dr Tickoo.

For malaria, there are effective drugs available for treatment, so a correct diagnosis helps to start timely antidotes. For prevention too (in case one is going to an endemic region), a week-long course of prophylaxis is advisable. “For dengue and chikungunya, though, there is only symptomatic treatment—paracetamol, hydration, etc. It is important not to take painkillers—ibuprofen, diclofenac—as these bring down the platelet count and may cause gastritis, breathing problems,” says Dr Tickoo.

Do not self-medicate or rely on chemists as there are just too many kinds of viruses around. “Incorrect medication or waiting too long to go to the doctor can mess up a case,” warns Dr Kaur.