New malaria scare in rural TZ

Sunday May 21 2017

Anopheles funestus mosquito. PHOTO | FILE

Anopheles funestus mosquito. PHOTO | FILE 

By Syriacus Buguzi @buguzi

Dar es Salaam. A unique mosquito species recently identified by researchers in Tanzania is now to blame for 90 per cent of the malaria burden in rural parts of the country, a new study by scientists from the Ifakara Health Institute (IHI) shows.

The mosquito species—anopheles funestus—which the scientists have described as “notorious” occurs in very small numbers as compared to other mosquito species, but it is extremely active at transmitting malaria to humans, reveals the study published in Plos One Journal.

Results of the new study conducted in south eastern Tanzania suggest that anopheles funestus mosquito is now a major malaria vector [and that this was not known.]

Nearly nine in every ten malaria infections in rural Tanzania are now carried by this mosquito species says the study.

Findings show that this mosquito contributed to 86.2 per cent of malaria while the other known species, such as Anopheles arabiensis contributed to 17.8 per cent to malaria transmission in the study villages in South-eastern Tanzania.

The scientists say that this last remaining vector can survive even after contacting insecticide-treated mosquito nets that are commonly used in households to tame malaria transmission.

However, results of the new study suggest that the focus should now be changed from relying solely on bed nets as a major control of malaria spread to looking for alternative interventions, particularly those that can effectively address the problem of anopheles funestus.

The researchers’ suggestion comes at a time when recent malaria indicator survey of 2016 shows the average prevalence of 14.8 per cent of malaria in children under the age of 5 years.

The study found out that Anopheles funestus mosquito exclusively feeds on human blood, unlike the other [popular species] the Anopheles arabiensis, which were found to feed on both humans and cattle.

Following this study, there is now hope that the mosquitoes could now be targeted by household-based interventions and eventually protect humans from malaria.

The researchers believe there is need for complementary approaches in eliminating malaria in the country after realizing that there was a burden of the disease still attributed to “largely” unknown mosquito species.

Lead researcher from IHI, Mr Emmanuel Kaindoa, says, “We have clearly shown that anopheles funestus mosquitoes are highly resistant to pyrethroids used[in treating bed nets], and that they also survive unexpectedly longer than the other malaria mosquitoes, thus requiring new control approaches to tackle the residual malaria.”

ut also, Tanzania has experienced a decline in malaria transmission following the introduction of insecticide treated nets (ITNs).

By the year 2010, the country had made significant progress, and most areas that were experiencing malaria prevalence of above 50 per cent by the year 2000, are now below 10 per cent prevalence.

Mr Kaindoa emphasizes that investing in interventions which effectively target Anopheles funestus mosquitoes could significantly improve control of the ongoing persistent malaria transmission in south-eastern Tanzania.

In Tanzania, malaria is known to be transmitted by many Anopheles species. The transmission occurs when a mosquito injects malaria parasites in human blood by a Female Anopheles mosquito during its blood meal.

The World Health Organization (WHO) says malaria continues to be one of the most significant mosquito-borne parasitic diseases, affecting about 212 million people, causing 429,000 deaths annually and adversely affect socioeconomic development in sub-Saharan African countries.

This year, WHO laid down a new strategy calling on governments to eliminate malaria.

The UN Health Agency has provided countries with a new set of tools and strategies for achieving and maintaining the elimination, regardless of where the countries lie across the spectrum of malaria transmission.

Currently in Tanzania, 90 per cent of the population lives in areas that carry a high risk of Malaria transmission, the National Malaria Control Program.

Tanzania has the third largest population at risk of malaria in Africa, says and each year, 10 to 12 million people contract malaria in the country and 80,000 die from the disease, most of them of them children.

It may take many years to eliminate the disease on the mainland but in the Isles, the Zanzibar Malaria Elimination Program (ZAMEP) focused on pre-elimination as its vision for2018. Reports show that the Island may have no locally-acquired malaria cases by that year.

Zanzibar managed to cut down the malaria prevalence from 40 per cent in 2005 to below one per cent in 2013, by adopting the out-door residual spray, raising awareness and the use of treated mosquito nets as well as proper diagnosis.