Many tourists worry about mosquitoes ahead of a trip to Zanzibar.

Not only because the many mosquitoes present a substantial nuisance,

but also because the associated risk of various mosquito-borne diseases.

However, far fewer tourists consider how tourists may add to the number of

mosquito breeding places and increase the use of chemical insecticides.

This affects not only the tourists themself

but also the environment and the health of the community.

Researchers from the State University of Zanzibar have found that

the local environment in and around the hotels create good opportunities for mosquitoes.

This high mosquito abundance may be caused by

intense use of water to maintain the hotel compound green.

Let's ask Fatma Saleh,

one of the local experts in mosquito-borne diseases,

how hotel and their surrounding environment

may impact the number of mosquitoes here in Zanzibar.

In the gardens you'll find trees.

And if there are tree holes in the trees,

these tree holes could collect water and they'll become breeding sites.

Drainage areas or, is that an issue?

No, drainage also is an issue.

And a lot of mosquito, like Culex mosquito,

breeds a lot in the drainage systems,

in the collection chambers,

or in the wastewater treatment systems.

They also produce spots for mosquito breeding sites.

The hotels, what do they do about the problem?

How do they control mosquitoes?

Well, the hotels know that mosquito is a problem.

Because, tourists complains a lot about this,

and if tourists are not happy they'll give bad reviews.

They don't want bad reviews,

because it's bad for their business.

So, what they do is that,

they're trying to fight mosquitoes by dealing with adult mosquitoes.

What they're doing is that they are spraying insecticides on daily basis, in the rooms.

They also spray once or twice per week.

They're spraying the entire compound.

But also, on monthly basis they're doing fumigation.

It's an extensive spraying of the whole compound inside and outside the buildings,

to get rid of the adult mosquitoes.

They are dealing with adult mosquitoes.

But, what they don't realize is that,

when you are using insecticides spraying it very often,

and in the long period of time,

you are causing resistance to these mosquitoes.

The mosquitoes becomes used to these insecticides and they become,

these insecticides become less effective.

So, they don't realize that, they're spending a lot of money,

dealing with adult mosquitoes by spraying with insecticides and cutting a lot of costs,

but in the end these mosquitoes they don't die,

because they are resistance to this.

And another danger is that when the mosquitoes are resistant to these insecticides,

and if the population,

if the whole coast of Zanzibar have the population of mosquitoes which are resistance,

in case we have an introduction of

a virus that are transmitted by mosquitoes in these areas,

then it will be very difficult to control this diseases.

Unfortunately most of the insecticides used by the hotels are the same

as the ones the public health authorities will use in case of disease outbreaks.

But as Fatma explains,

the health authorities may no longer be able to control the disease outbreaks as

these insecticides will lose their effectiveness due to insecticide resistance.

So are there other problems linked with the use of insecticides at the hotels?

Yes, apart from development of resistance to the mosquitoes.

Yes, insecticides are chemicals.

So, when they're used for a long time they also destroy the environment.

There are birds out there and

other animals that get affected by these chemicals that are being sprayed continuously.

But also, the staff that are actually

spraying these insecticides on daily basis or weekly basis,

they could also get health problems.

Imagine there is someone who is asthmatic,

spraying all these all the time,

inhaling all these chemicals,

yes it might be a problem.

So, what should the hotels do?

Well, there are best options for the hotels to

opt or to use rather than using insecticides all the time.

Instead of targeting the adults that are flying out there,

they could target the sources,

where the mosquitoes are actually produced.

The breeding places.

They could do the environmental management practices.

Looking at the breeding sites,

getting rid of those, cleaning the gutters,

taking care of the liquid waste channels,

taking care of plants in the gardens,

filling the holes in the trees.

They could do this and they could reduce

the mosquito population tremendously rather than spraying all these mosquitoes.

Research on the environmental and human health impacts of insecticides remain to be done.

But several hotels have expressed interest in supplementing

insecticide-based mosquito control with environmental non-chemical solutions.

This is in line with the World Health Organization's recommendations of reducing

the mosquito abundance by systematically eliminating mosquito larvae habitats.

This is in particular relevant for Aedes mosquitoes.

The Aedes mosquito, which can carry both dengue,

Zika, and yellow fever,

is often found in urban areas.

But large tourist resorts offer plenty of

breeding ground similar to the ones found behind a common urban building complex.

You see that spot over there?

Do you see there are some coconut shells?

Let's go and have a look if there are larvae in it.

Because, these kind of materials,

they can be perfect breeding places for mosquitoes.

And if they stay with water for more than three days,

you will surely find mosquitoes.

And if you look here, come closer, you see here?

Over these, do you see?

Actually there is an adult mosquito,

adult Aedes mosquito there ovipositioning,

laying eggs over there right now as we see it.

You see? It's there,

and there are some larvae in it.

To prevent the development of mosquito larvae turning into adult mosquitoes,

the facility maintenance staff, room service staff,

gardeners, and others must ensure that water

cannot collect for a longer period of time in,

for example, small decorated fountains,

drain, or subsurface pipes.

So, just a habitat like this,

would there be plenty of opportunities for mosquitoes to emerge?

Oh, yes. That's why it's very important for

municipal council or whoever is dealing with solid waste to manage the waste properly.

Well, this could be caused by simple littering habits by people.

And then there is no efficient collection

of the waste and then the waste stays on the streets,

and these kind of materials become perfect spots for mosquito breeding.

Because of the extraordinary pressure on

the domestic water supply and the unreliability of service,

many households and hotels store water in big tanks.

Another perfect breeding site for mosquitoes,

if not completely sealed.

People usually keeps tanks and other water storage materials in their homes.

So, if it's got opening and mosquito could go through it and get into the water,

they will oviposition and lay

their eggs in there and you may find some larvae or pupa in it.

Since it's big, and there's a lot of water in it,

if a mosquito goes into that,

lay eggs, you will find a lot of mosquitoes coming out.

So, what would the environmental management plan for mosquito control entail?

Before chemicals such as DDT and organic phosphates were available to control pest,

the fight against mosquitoes was based upon the use

of various biological and environmental measures.

This form of control is often termed Environmental Management for Mosquito Control.

And is commonly divided into three different types of interventions.

Environmental modifications,

entailing a long lasting physical transformation to reduce mosquito larvae habitats,

such as drainage of marshy areas.

Secondly, environmental manipulation.

This entails a temporary change to mosquito habitats involving, for example,

frequent emptying of water storage containers, cleaning of gutters,

proper disposal of discharged containers,

and the management of plants close to homes

to prevent collecting of water in leaf access.

Thirdly, changes to habitation or human behavior,

are actions to reduce human mosquito contact,

such as installing mosquito screens and windows, doors,

and other entry points,

and using mosquito nets while sleeping.

In this way, by systematically surveying

a resort and the neighboring areas at different times of the year,

it will be possible to identify places where mosquitoes lay eggs and larvae develop.

With close involvement of hotel maintenance staff and community representative,

an environmental management plan can be developed,

aimed at minimizing the number of mosquito habitats,

and thereby the proliferation of adult mosquitoes emerging in and around the hotels.

A way of reducing the number of mosquito habitats at a resort is

to mosquito-proof all water storage containers used for rainwater collection,

open wells, and wastewater collection points.

It's also important to ensure proper storage,

collection, and disposal of solid waste.

A hotel could be constructed in ways that minimize

the availability of mosquito habitats by design of gutters,

water collection points, water supply schemes, and garden areas.

Adding larvae-eating fish to small fountains and

decorating ponds might also be needed to control the mosquito larvae.

As indicated by the figure,

disease carrying mosquitoes, such as Aedes aegypti and Aedes albopictus,

have a wide distribution throughout the global tropical and subtropical regions.

Therefore, eliminating mosquito habitats at resorts will contribute

towards reducing mosquitoes as a nuisance and protect against disease.

Control of mosquitoes at tourist destinations

Sustainable Tourism – promoting environmental public health

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