What flies and cockroaches carry

Carried on the outside, not injected

A mosquito injects something into you. A fly does not, and neither does a cockroach. They are what public health people call mechanical vectors: they pick things up on their feet and bodies in one place and put them down in another.

The other place is usually a drain, a refuse heap, or human or animal waste. The place they put it down is usually your food.

A housefly also does something worse than walk. It cannot chew, so it vomits onto solid food to soften it and then drinks the result. Whatever was in its gut goes onto your plate with it.

This is why the answer to both of them is covering food and cleaning surfaces, rather than anything more elaborate.

What that can mean in practice

The illnesses associated with contaminated food and water in Nigeria are the familiar ones: typhoid fever, cholera, dysentery and the broad category of diarrhoeal disease. Cholera in particular appears in outbreaks, often in the rainy season, and the NCDC publishes on it.

Flies and cockroaches are one route by which contamination reaches food. They are not the only route, and usually not the main one. Unsafe water, unwashed hands and poor sanitation account for more.

That is worth being honest about rather than overselling. Killing the flies in a kitchen with an open drain running past it fixes the smaller half of the problem.

Cockroaches carry a second, separate risk that is not about food at all. Their droppings and shed skins are a well-recognised indoor allergen and asthma trigger, particularly for children in homes with heavy infestations.

What actually reduces it

Cover food. All of it, all the time, cooked and raw. A mesh cover costs almost nothing and does more than anything else on this list.

Deal with the water. Cockroaches need it more urgently than they need food, so a dripping tap or a wet dish rack is an invitation. Flies need somewhere wet and organic to lay.

Deal with the waste. Bins with lids, emptied often, kept away from the kitchen door. Animal waste cleared. Drains kept running rather than standing.

Wash hands and wash surfaces, especially before food is prepared and after it is cleared.

Then treat. An aerosol reduces the number of insects in the room, and treating the harbourage behind and under units deals with cockroaches where they actually live. Do it as the last step rather than the first, because insects that are killed and then replaced from an uncovered bin have not been solved.

Treating a kitchen without contaminating it

Clear the worktop first. Cover or remove food, plates, cutlery, chopping boards and the kettle.

Never spray onto a food surface, into an open pot, or across a preparation area.

Treat the gap and the void: behind the cooker, along the skirting, under the units. That is where cockroaches are, and it keeps the product away from where you eat.

Leave the room closed for the time the label states, then open the windows and let it air. Wipe down any surface that will touch food before you use it.

Keep children and pets out until it has aired. Read the label before you start and follow it rather than this page if the two ever differ.

What this page is not

This is general information about insects and the illnesses associated with contaminated food. It is not medical advice.

No product sold by C-Success prevents, treats or cures typhoid, cholera, dysentery, asthma or any other illness. TOPRANK and VANISH are insecticides, and killing insects is the whole of what they do.

If somebody has persistent diarrhoea, a high fever, or signs of dehydration, that is a clinic visit and not a housekeeping problem. Cholera in particular can become dangerous quickly and needs treatment, not a clean kitchen.