Dengue: what to watch for, and when to call a doctor

Dengue circulates in Mauritius through the warm, wet months, and the questions that reach us at night are nearly always the same three: is this dengue or chikungunya, what is safe to take for the fever, and how do you know when it has stopped being something to manage at home.

Most people who catch dengue recover at home. One part of it is worth understanding properly, though, because it is the part that catches families out: dengue does not always run in a straight line downhill. A small number of people become more unwell just as the fever breaks.

What dengue actually is

It is a virus carried by mosquitoes. The ones that matter here are the Aedes mosquitoes, which bite in daylight rather than at night, most often in the early morning and the late afternoon. They breed in very small amounts of clean, still water: the saucer under a plant pot, a blocked gutter, a bucket left in the yard, the rim of an old tyre.

It does not pass from person to person. A household tends to fall ill together because the same mosquitoes are biting the same people, not because they are giving it to one another. Symptoms usually appear between four and ten days after the bite.

Four types of dengue circulate worldwide. Recovering from one gives lasting protection against that type only, which is why it is possible to have dengue more than once.

What it feels like

Dengue usually starts abruptly. Most people can name the day it began.

• A fever that arrives suddenly and climbs high, often 39 to 40°C
• A severe headache, with pain felt behind the eyes
• Deep muscle and bone aching, which is where the old name breakbone fever comes from
• Nausea, vomiting, and no appetite
• A red rash or flushing, often a few days after the fever starts
• Fatigue that outlasts the fever by a good while

In the first day or two it is easily mistaken for flu. In a young child it can be quieter than the list above: a high fever, irritability, less interest in food and drink, and vomiting, with nobody able to describe a headache or pain behind the eyes. With a small child, what is worth watching is not the description but the fluids going in and the level of alertness.

Dengue or chikungunya? Why the first few days matter

Early on the two look alike: abrupt fever, headache, aching, rash. They are carried by the same family of mosquitoes and circulate in the same season. Dengue tends to hurt behind the eyes and in the muscles, and chikungunya most in the joints, but neither pattern is reliable enough to bet a treatment on.

Until a doctor has ruled dengue out, avoid aspirin, ibuprofen and diclofenac. The anti-inflammatories many households keep for aches and joint pain are precisely the wrong ones here: dengue lowers the platelet count, and these medicines add to the risk of bleeding on top of it. Paracetamol is the one to use while the diagnosis is still open.

If someone has already taken an anti-inflammatory, say so when you call. It is useful information, not a confession.

There is a companion piece to this one written from the other side of the same question: chikungunya, what to do at home and when to call.

The days when the fever breaks

This is the part of dengue least well known outside medicine. The fever usually lasts somewhere between two and seven days. In most people it settles and recovery begins from there. In a small number, the hours around the fever settling are when the illness turns, and someone who appeared to be improving becomes unwell again.

That is not a reason to sit up in fear for a week. It is a reason not to read the fever breaking as the all clear, and to keep an eye on fluids, urine and alertness for a day or two after it does.

What to do at home in the first few days

1. Rest, and expect to need more of it than you think

This is not an illness to work through. The fatigue is part of it, and people who push against it in the first week tend to have a longer second week.

2. Drink more than you feel like drinking

Fever, sweating and a lost appetite take fluid out faster than thirst puts it back. Water, oral rehydration salts, soup, whatever will be taken. Small amounts often are easier to keep down than a full glass. Passing urine regularly, and pale rather than dark, is the simplest sign at home that it is working.

3. Paracetamol for the fever and the pain

At the dose printed on the packet, and no more. Nothing else from the medicine cupboard while the diagnosis is open. If it is not touching the fever or the pain, that is a reason to telephone rather than a reason to add something stronger.

4. Keep the patient away from mosquitoes for the first week

A mosquito that bites someone with dengue can carry it to the next person in the house. A net over the bed during the day, screens kept closed, repellent on exposed skin: that is what keeps it to one person instead of going round the family.

When to call a doctor

For most people the honest answer is: whenever you would rather have it looked at than guessed at. Specifically, call if:

• The fever has been there three days or more, or it settled and has come back
• The pain is not answering paracetamol
• There is repeated vomiting, or fluids are not staying down
• Urine has become dark, or there has been very little of it
• There is easy bruising, or the gums bleed when brushing
• The patient is over 65, pregnant, a newborn, or lives with diabetes, heart disease, high blood pressure or kidney disease

That last group is not a warning that something will go wrong. It is simply the group in whom dehydration and the strain of a fever are least well tolerated, and in whom a doctor would far rather see the patient early than late.

Do not wait for a home visit. Go to the nearest hospital emergency department or call SAMU on 114 if there is bleeding from the gums or nose, blood in vomit or stool, severe abdominal pain, breathlessness, cold or clammy skin, confusion or unusual drowsiness, a fit, or a fever in a baby under three months.

What a doctor does at the house

An examination, and a judgement about which illness this is and which phase it is in. Where it is useful, blood can be taken at the address: a dengue test, and a full blood count, which is how the platelet count is followed rather than guessed at. Where the fever, the pain or the fluids need treating, first-line treatment can begin during the same visit.

What a visit really provides is that you are not deciding alone whether this is the ordinary course of a viral illness or the point at which it needs more. Consultation fees are the same anywhere on the island, and are published in full: what a home visit costs.

Stopping it at your own gate

The mosquito breeds close to the house, which means most of what works is done in the yard rather than at the pharmacy.

• Empty standing water once a week: plant pot saucers, buckets, gutters, old tyres, pet bowls
• Repellent on exposed skin in the early morning and the late afternoon, when this mosquito bites
• Screens on the windows, or a net over the bed
• And a net over the patient’s bed too, for the first week of the illness

How widespread it is

Dengue activity in Mauritius rises and falls with the season and moves week by week. For the current position, and for any public health guidance in force, the Ministry of Health and Wellness is the source to check rather than this page.

Frequently asked questions

Is there a treatment for dengue?

There is no antiviral that cures it. Treatment is aimed at the fever, the pain and above all the fluids, which for most people is enough. What a doctor adds is certainty about the diagnosis, pain relief that is safe to take, and someone following the illness through the days when it can change.

How long does dengue last?

The fever usually lasts between two and seven days. Tiredness commonly outlasts it by a week or two, and sometimes longer. Recovery is rarely a straight line, and a day that feels worse than the one before it is not by itself a cause for alarm.

Can you get dengue more than once?

Yes. Four types circulate, and recovering from one gives lasting protection only against that type. A later infection with a different type carries a higher risk of the severe form, which is why a second episode is worth having seen rather than managed on the strength of the first.

Can dengue spread from person to person?

No. It is carried by mosquitoes, not by contact. Households fall ill together because they share the same mosquitoes, which is why protecting the patient from bites during the first week is what stops it going round the family.

Can a doctor treat dengue at home in Mauritius?

Yes. A day consultation between 7am and 7pm is Rs 2,000 and a night consultation between 7pm and 7am is Rs 3,000, at the same rate anywhere on the island. Blood can be taken at the address.