Dar es Salaam: Following World Health Organisation's (WHO) alert on a new and more potent malaria vector in Africa, Tanzania is taking measures to strengthen vector surveillances and monitoring updates.

Researchers, academia, and national malaria control programme are collaborating to ensure the vector monitoring system can detect any new vectors and provide updates as guided by WHO. WHO issued a vector alert following recording the Anopheles stephensi, in Djibouti in 2012. The potent mosquito species was recorded in 2016 in Ethiopia and Sudan and in 2019 it was recorded in Somalia. It breeds easily in urban areas and evidence shows that where it has been recorded rates of malaria were also comparatively higher.

Most recently, WHO facilitated in a training of district vector surveillance (and control) officers (DVSOs) who collect mosquito samples in district 32 sentinel sites across the country for analysis. Other institutions that participated in the training of 56 vectors surveillance officers are the national institute of medical research, national malaria control program, Ifakara health institute, PSI, and the ministry of health.

“Vector behavior is a critical science in disease control. The behavior of mosquito that transmit malaria is critical to design tactics to control or limit human contact with the vector. Using the knowledge of the behavior and biological make up of vectors including anopheles, experts have developed chemicals for spraying and insecticide treated nets,” said Dr. Jovin Kitau, WHO Malaria Expert.

The malaria vector entomological surveillance was established in Tanzania in 2016 with support from WHO, the WHO has since been providing guidance in updating the protocol and review of collected data.

Tanzania is one the four countries in the world that contributed to just over 50 percent of the malaria deaths. The determination to eliminating the diseases is exemplified in the milestones reached in the recent past.

During the training, a total of 56 officers that participated in this training got certificate to recognize their participation. The Ministry of Health and the World Health Organization are proud to have their logos on these certificates. Catching mosquitoes and studying them is a crucial undertaking in the fight against Malaria.

The current national malaria control strategy will end in 2025. A midterm review conducted this year praised progress in most of the indicators but Malaria parasite prevalence in children aged less than 5 years recorded an 8.1 percent, above the midterm target of 5.0%.

Malaria Mortality rate in health facilities, supposed to contract to the lowest level possible reached 2.2 per 100,000 population against mid-term target of 3 per 100,000 population.    

Malaria parasite prevalence among children below five fluctuated downward, 18% in 2008, down to 9.5 in 2012, up to 14.8 in 2015 and in the last review it was recorded at 8.1. Among pregnant women, another vulnerable group, the rate of malaria positivity was recorded at 6.2%, down from 7.7% in 2020.

One performance being watched is limiting human contact with malaria causing mosquitoes. The strategic plan aims to prevent human-vector contact in a cost-effective manner to cover the entire population at risk of malaria in all settings. Rendering the environment unsuitable for mosquito breeding and killing mosquitos before they contact humans are the two strategies.

Experts monitor the rate of infective mosquito bites (entomological inoculation rate-EIR). In 2018 EIR it was estimated that a person in Tanzania got nearly 3 bites from mosquitoes that carried the malaria causing organisms. The mid term review showed that EIR went down to 0.97 infective bites per person, 65.5% reduction from 2018 levels.

Estimation of risky mosquito bites yield useful intelligence to fight malaria. Malaria vector surveillance officers from 32 sentinel sites of the government, collect, identify malaria then transport samples of dead female anopheles for more in-depth lab analysis at a designated centre of the National Institute of Medical Research in Muheza Tanga.

 Chosen from locations that represent a varied rate of malaria prevalence in Tanzania, the vector control officers provide vital information that informs decisions on malaria prevention in Tanzania.

“If I don’t do my job diligently, I may be misleading decision makers by providing information that does not help them make the right decisions about malaria interventions in vector control and treatment,” said Paschal Thobias Lutubija, a Malaria Vector Surveillance Officer from Ruangwa district.

This knowledge about behaviors of vector is useful to develop tactics to stop their contact with human. Vector behavior evolves through 'insect learning’ and mutations; therefore, continuous studying of the vector informs updates to malaria interventions in all aspects from preventing bites to developing insecticide formulations that kill the malaria vectors.