Where is IRS most feasible?

In Nigeria’s Rivers State the State’s Malaria Control Coordinator reports on “efforts to roll back malaria in Rivers State, (in which) the state government says it would carry out indoor residual spraying (IRS) to terminate mosquitoes, the causative agent as from this quarter.”

The Coordinator has set up a timeline: “According to her, plans were already underway to purchase and distribute chemicals that would be used for the house-to-house spraying. She also said that if done every six months in the next three years, Rivers State would be free from malaria.”

WHO explains that, “The application of IRS consistently over time in large areas has altered the vector distribution and subsequently the epidemiological pattern of malaria in Botswana, Namibia, South Africa, Swaziland and Zimbabwe.” These are countries with large areas of unstable or epidemic malaria where annual spraying is effective.  Rivers State, Nigeria, as its Malaria Coordinator notes, requires twice a year spraying since it is an area of stable, intense and year-round transmission.

When the US President’s Malaria Inititive planned IRS in Ghana it chose districts in the Northern part of the country where malaria transmission is more seasonal and IRS can be cost-effective when used only once a year. For most of the country PMI is planning to distribute more than a million long lasting insecticide-treated nets as the appropriate strategy.

The Rivers State effort, while recognizing the need to adapt IRS timing to its ecological/epidemiological setting will still face huge challenges including –

  • dispersed, nearly inaccessible riverine communities
  • coordination among neighboring states where mosquito control efforts may not be as strong
  • ongoing civil disorder wherein “Militants in the Niger Delta attack pipelines and other oil facilities and kidnap foreign oil workers.”

Apparently the State is also relying on the bednet option, and “government had distributed four million insecticide treated bednets during the last immunisation campaign in the state. But this spraying option would ensure that even those who fail to clean their areas get the needed cover.” Nets can be distributed and monitored through a variety of community channels and last for 5 years if used properly.  This might be a safer and more viable vector control option for such a high transmission areas.

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