Researchers attribute the surge in malaria cases in Northern Uganda to climate variability

By Kei Emmanuel Duku

Arua I A research conducted by the Swiss Tropical and Public Health Institute in partnership with the Uganda Ministry of Health and Makerere University School of Public Health have attributed the ever-increasing cases of malaria registered in lowland areas to changing rainfall pattern, temperature and humidity.

The research, titled: “Interactions between Climatic Changes and Interventions Effects on Malaria Spatio Temporal Dynamics in Uganda,” was published in 2018, by Penelope Vounatsou from Swiss Tropical and Public Health Institute alongside Simon Kasasa of Makerere University School of Public Health and Dr. Jimmy Opigo, Assistant Commissioner Health Services and National Malaria Control Program Manager, Ministry of Health, among others.

The research found that malaria transmission in low-lying areas is enabled by a conductive climate that is characterized by ample rainfall, optimal temperatures of 26-28 Degrees Celsius and humidity above 800-1000 ft above sea levels that offer humble breeding grounds for mosquitoes.

Malaria is caused by female Anopheles gambiae s.l (Anopheles Mosquito) a dominant vector species found in Sub-Saharan Africa, followed by Anopheles Funestus which thrives well in permanent water bodies and growing vegetation cover. The two vectors are said to be endophagic and endophilic in a way that they can feed indoors and rest on walls after feeding.

According to the same research, Anopheles fenestras mosquitoes can hide in between gaps in walls, rooftops and reeds of traditional houses and they are active late evening.

The scientists further noted that there is an interrelationship between temperatures and life cycles of the malaria parasite and the lifespan of the vector, development of larval and its survival.

They cited that optimum or moderate temperatures range of between 26-28 Degrees Celsius offers humble ground for the development of larval while low temperatures below 17 or 35 degrees Celsius lowers the growth and formation of the embryo of undeveloped vectors and increase chances of moralities, while rainfall aid growth and continuous sheltering of mosquitoes breeding sites which subsequently add on the vector’s population.

In Uganda, the recent occurrence of flooding in 2019 along the River Nile and droughts in Northern Uganda have had an impact on the transmission of malaria in the affected areas like Gulu, Amuru, Omoro, Oyam, Amuru; Adjumani, Moyo and Obongi.

Others are Yumbi, Arua, Terego and Koboko, among others in West Nile sub-region.

According to the weekly malaria report released by the Ministry of Health, between 24 July 24 to July 30, 91.5 per cent (196,000) patients tested positive and were treated for other related complications whereas 3.1 per cent tested negative (6,000) out of the 98.2 per cent (407,000) over roll patients who sought medical attention.

There was a positivity rate of 47.0 per cent from the first week of July 2023.

Records further revealed that Agago recorded 5,880 cases at 70.4 per cent cases, Nwoya at 68.7 per cent, and Oyam at 68.4 per cent. Amuru and Maracha recorded 67.7 per cent, respectively. The districts are among the top 10 districts which registered the highest number of malaria cases in July.

Other top districts are Pader, 5,479 cases, Kitgum, 3,804, Lamwo, 3,759; Yumbe, 6,715, Adjumani, 3,763 and Madi-Okollo, 3,487.

“From the beginning of the year 2023, the country experienced a reduction in cases. After week 15, cases started rising to date, consistent with the first peak after first season rains (April-July),” reads the record.

World Health Organization (WHO) asserted that Uganda has the World’s highest malaria Incidence Rate of 478 cases per 1,000 population and malaria is responsible for about 40 per cent of outpatient department visits, 25 per cent of admissions, and 14 per cent of deaths.

Every year about 70,000 to 100,000 deaths are registered in Uganda with children below 5 years and pregnant women at risk.

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In the first week of July, more than 20 cases of mortalities were registered across the country where Lira Regional Referral Hospital recorded 3 cases, the highest while Mbale Regional Referral Hospital recorded a single case.

In the West Nile sub-region, 2 death cases were registered at Jomorogo Health Centre III in Yumbe district and were ranked second in the country among the health facilities that registered high cases of death in July.

Gulu Regional Referral Hospital in Gulu City and Dr Ambrosoile Memorial Hospital Kalongo in Agago registered one death each.

Dr Jimmy Opigo, Assistant Commissioner of Health Services and National Malaria Control Program Manager at Uganda’s Ministry of Health noted that apart from temperatures, rainfall and humidity, other factors such as poor housing, poverty and low literacy level are some of the contributing factors towards high prevalence of malaria.

He commented that the most burdened are Karamoja with 30. 2 per cent prevalence followed by West Nile at 23 per cent, Busoga and Lango are last.

Kampala is the least with less than 1 per cent together with the Mountain Elgon region and Kigezi Islands. He, however, attributed the low prevalence rate in the two regions to low temperatures as they are found in high-altitude areas.

From the research conducted, temperatures above 26-28 degrees Celsius do not support the proliferation of both mosquitoes and the malaria parasite.

Dr Jimmy further said the variation in the malaria cases is sometimes caused by geographical locations where districts in West Nile lie between 600 to 1650ft above sea level with Mountain Otce in Moyo district having the highest peak.

Adjumani and Obongi districts including the other low-lying areas of Laropi along the Nile belt, Dr Opigo said has an altitude of 600-800ft above sea level making the area fairly hot and favourable for mosquitoes and malaria parasite to breed in.

According to Dr Opigo, the high transmission rate of malaria in West Nile is beyond temperatures he said the nature of mosquitoes and behavioural changes of the community who sometimes opt to sleep outside during dry season because of high temperatures, expose them to mosquito bites.

Anopheles Venustus type of mosquito he said is unique because it can both bite inside and outside, rest inside and outside, more so it also breeds well during dry seasons (during warm temperatures) contributing to high transmission rates in Moyo, Adjumani; urban areas and other areas of West Nile.

“So, you will find in the dry season malaria is heavily transmitted in these regions. Again loss of traditional protection ways like a campfire or bonfire, if you sleep out, it will be smoking away the mosquitoes. This traditional practice is no longer there. Also, traditional practices of smearing houses during Christmas in October, around Easter with cow dung all have vanished, that’s why we have high cases of malaria during dry seasons,” Opigo explained.

The lifecycle of mosquitoes consists of eggs, larval, pupae and adult stages, but for it to be complete it requires a conductive environment like valleys, swamps, stagnant water in broken pots, basins; areas within bathing shelters for mosquitoes to lay eggs and hatch them.

Dr Jimmy stressed that seed temperature, rainfall and humidity are other determinants of mosquito multiplication, and this is because when the rain comes, it gives water for mosquitoes to lay eggs, the right temperatures also increase the maturation time. The humidity allows their vitality and feeding.

Weather focus released by Uganda National Meteorological Authority for June, July and August shows Northern Uganda’s sub-regions of West Nile, Acholi and Lango will receive average rainfall which will result in increased cases of respiratory diseases and skin allergies.

Dr Sule Ismail Bungu, a Public Health Expert and Researcher formerly with WHO South Sudan, stated that malaria posed a great threats to low and middle-income countries and is ranked the sixth leading cause of death in low-middle-income countries.

Dr Bungu also echoed that climate change has greatly contributed to the increase in malaria cases. This is because warm temperatures of about 33 degree Celsius offers breeding sites for malaria parasites but people who settle in high altitudes areas are less immune to malaria because mosquitoes do not survive in cold (low) temperatures compared to low lands that have high temperatures.

Northern Uganda and greater parts of West Nile are located in the Tropics and it has a hot and moderate-dry climate with average rainfall that tumbles between early April and mid-November. This rainfall supports the growth of green vegetation in the lowlands areas.

During this period malaria cases tend to increase because mosquitoes depend on the moisture from the vegetation cover and streams, valleys and swamps, including stagnant water.

Dr Sule also warned that frequent cutting of trees for wood fuel or charcoals and other domestic use in highland areas is likely to increase temperatures hence giving a good environment for the survival of mosquitoes.

“In the lifecycle of mosquitoes, they tend to perform better in relatively warm environments compared to cool temperatures. But as the temperatures keep increasing the conditions continue to become better for them to multiply and increase in number. So high temperatures mean high multiplication and high cases of malaria transmission,” he noted.

The pattern of malaria peak does not concede with the rainfall season, he said, citing lower malaria transmission during December to January partly because of less amount of rainfall received, reduced amount of water in swamps and streams as well as less stagnant water during dry season. But between March and May cases of malaria transmission begin to increase, he said.

“But the greatest peaks of malaria transmission happen in July, August up to October when many are experiencing increased rainfall. Consequently, we have a lot of breeding environments for mosquitoes,” he added.

West Nile districts are among the highly burdened districts in Uganda and Dr. Ismail attributed it to the hot temperatures, moderate rainfall received throughout the year but also unreasonable use of land where some people dig water channels to collect water for irrigation.

In Moyo district, Moyo Mission Health Centre IV in the first week of July registered 53 cases of malaria and 20 tested positive while the rest were negative.

Mindraa Sharoon, a Clinical Officer at Moyo Mission Health IV stated that most patients come to the facility showing up signs and symptoms like fever, vomiting, headache and diarrhea within children, while elders show signs of body or joint pains and general body weakness.

“The best way is to keep our surrounding clean, drain stagnant water, dispose of broken bottles well and above all sleep under mosquito nets: not only mosquito nets but well-treated Long Lasting Insecticides (LLIN) to reduce the rate of transmission,” Sharoon emphasized.

According to Aluma Mazmaile, a Clinical officer at Moyo General Hospital working at the Emergency Unit, on average, 7-10 cases during dry seasons are registered at the Unit, adding that the figures rise between 10-15 in a week during rainy seasons.

Although there is still scanty information about the relationship between malaria treatment and the impact of climate change, the Ministry of Health revealed they intend to carry out a rapid assessment of LLIN coverage in Kibuku district. This is a district with a persistently high malaria burden despite several interventions.

In West Nile, Aluma noted that there have been treatment failures associated with the use of Coartem and other Antimalarial drugs. He said the obvious reason for drug failure can be linked to under-dosage or incomplete treatment by patients.

“The research is still on and I may not give you a definite answer but I can confirm that recently there was a treatment failure reported in this hospital (Moyo General Hospital) with Coartem and we also got medical information that there was drug resistance to Artemisinin, Artesunate from Northern Uganda,” said Aluma.

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