A swarm of pesky mosquitoes

The rainy season is upon is upon us, cooling the long summer nights. Just as I retire to sleep after a good days work, the slumber is rudely interrupted. The irritating sound is intensifying, and the truth is there could only be one thing which could be such a menace, its long –legged and two winged, the mosquito! 

A good sleep is ruined as I rise to swat, clap and whack at the insect with the hope that it would be squashed in the process. I miss, not once but repeatedly, it disappears. I give up and go to bed. 

A woman sleeping under a mosquito net. Source: Wikipedia Commons

Moments later the buzzing returns. Just as I gear for combat, it seems the mosquito is just as prepared. It strikes! I yell in agony and accept defeat. The insect gets to live another day. 

Well, we can all relate to the insect in questions antics. Not only annoying, the mosquito, particularly the biting female anopheles carries and transmits malaria. 

Malaria in Botswana: The Statistics

According to The World Health Organisation Africa Region Malaria is an acute febrile illness caused by Plasmodium parasites, which are spread to people through the bites of infected female Anopheles mosquitoes. There are 5 parasite species that cause malaria in humans, and 2 of these species – Plasmodium falciparum and Plasmodium vivax – pose the greatest threat. Plasmodium falciparum is the deadliest malaria parasite and the most prevalent on the African continent. Plasmodium vivax is the dominant malaria parasite in most countries outside of sub-Saharan Africa. 

Mosquitoes usually lay their eggs in shallow, stagnant water. Photo: RLS Southern Africa

The word malaria itself comes from the Italian words mala aria, meaning bad air. The Romans thought that malaria was caused by bad air or dirty water from marshy areas (there was malaria in the Italian peninsula a long time ago before it was eliminated).

The epidemiology of malaria in Botswana is such that infections are seasonal. The transmission season starts in October and ends in May each year. Malaria transmission is most intense in the Northern part of Botswana which experiences higher rainfall levels than the rest of the country; however there are experiences of sporadic cases across the country.  

According to a malaria bulletin published in October 2022 by the Ministry of Health and Wellness; malaria trends in Botswana between the years 2008 through 2022 show that in the 15 years mentioned, the year 2014 registered the highest deaths at 22 of 1346 cases while 2017 registered a staggering 1900 cases, only 17 deaths were recorded. Malaria cases have been significantly reduced as a result of strengthened surveillance, community engagement and coordinated vector control activities. The numbers show that malaria deaths remained unstable over the past 15 years due to late healthcare seeking behaviour.  In 2022, 411 cases and 9 deaths were recorded. 

Aerial view of Gaborone. Source: Wikipedia Commons

In terms of cases by district, Kweneng East and West registered 13 and 17 cases respectively. Jwaneng recorded 12 cases while in Gaborone there were seven. The afore mentioned are areas not commonly prone to malaria cases as they are located in the southern part of the country which is often fairly dry and hotter which is not an enabling environment for the anopheles to thrive, unlike the wet and hot Chobe and Okavango districts.

Another shocker from the statistics is that between October 2021 and May 2022, Kweneng West recorded three malaria deaths while Ngami and Chobe listed only one each. 

Malaria morbidity and Mortality : 2008-2022

In a questionnaire to the Ministry of Health and Wellness, it is reported that; “The country experienced an outbreak in Kweneng and Samane area in the last transmission (2021/22) where they registered 33 cases and 13 cases, respectively. However in this current season (2022/23), the country has registered only 2 local cases from southern part of the country. These cases were reported by Kweneng between November and December 2022. It is too early in the transmission season to determine whether there is a decline in the number of cases. In mitigation against experiences of 2022, surveillance and community engagement have been strengthened.”

On the matter as to why there are cases in regions not common to have malaria, the Ministry responded that; “the outbreak of cases in non-endemic areas can be attributed to factors that are conducive for breeding of anopheles mosquitoes. Most of parts of the country have water bodies and lots of anopheles mosquitoes that can stimulate Malaria outbreaks.”

Aerial view of the Kavango Delta. Photo Vaughan McShane via Wikimedia Commons

Late December 2022, the Department of Meteorological Services reviewed the state of the global climate systems and updated the rainfall prospects for the months of January to April 2023. Most parts of the country will receive a normal to above normal rainfall with the south-western parts receiving above normal rainfall while temperatures will be normal with a tendency to below normal countrywide

Climate Change affects Mosquito behaviour

The WHO World Malaria report 2022 attests to climate change having an effect on the malaria map across the world. It notes that as climate change unfolds, it is feared the habitats of malaria mosquitoes will continue to expand. This does not only affect the countries currently worst hit by malaria. 

The World Bank report indicates that by 2050, climate change may cause some areas that were previously unexposed to malaria across China, South America and sub-Saharan Africa to be at risk, resulting in a 50% higher probability of malaria transmission. 

Climate change does not only mean catastrophes - it also means faster spreading of diseases among plants, humans and animals. Photo: Mercy Malikwa

If carbon emissions are not controlled, and the planet warms by just 2-3 degrees Celsius, the population vulnerable to malaria could increase by 5%. That’s around 700 million more people at risk. Just half a degree centigrade increase in temperature could mean an increase in mosquito abundance of up to 100%.

Despite uncertainties about exactly how climate change will affect malaria, it will certainly affect the geographical range, intensity and seasonality of vector-borne diseases. More broadly, climate change will directly affect human health across the world and threaten the capacity of health systems to manage and protect people’s health – particularly in areas of conflict and disaster, as climate change compounds these challenges. The WHO Operational framework for building climate resilient health systems is geared towards providing a wide range of guidance to support countries on health adaptation to climate change.

African governments have to set aside more money for mitigation and adaptation to the effects of climate change. This includes investing money in disease control. Photo: Macoco Bovi via Wikipedia Commons

Cover photo: Wikipedia Commons