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Should we be worried about the global spread of malaria?

This month we ask

Earlier this year, five people caught malaria in the US for the first time since 2003 – should we be worried about a global spread of the disease?

Dr Olayinka Osuolale

Lecturer, Department of Biological Sciences

Elizade University, Nigeria

The contrasting malaria cases between the US and endemic countries raises concerns about potential health issues associated with re-emerging diseases.

Considering the current situation in the US and the reports indicating internal infections, there are numerous gaps in information that need to be filled before drawing conclusions about a global link or the spread of the disease in the US. While it is crucial to take precautionary measures to prevent global spread, it is equally important not to be driven by fear. The lessons learned from the COVID-19 pandemic should guide our approach to disease monitoring and management, both at local and global levels.

It is essential to combat misinformation and fake news, as I encountered a TikToker with 2.2 million followers falsely labelling the disease as a viral infection originating primarily from Africa. Misinformation has the potential to undermine global efforts in addressing and combating diseases. This incident underscores the need for robust and operational health disease monitoring and alert systems, and preparedness to respond to infectious diseases, at local and global levels. It is crucial to approach the issues with balanced data, information and perspectives. The assessment of the global spread of any disease should be based on the current situation, expert guidance and official updates from relevant health organisations and authorities.

Emma Victory

Team Lead

UKHSA Malaria Reference Lab

The last UK malaria outbreak was during WW1, when invalided soldiers returned, often with vivax malaria, to hospital camps in mosquito-ridden marshlands. Most of those breeding grounds have since been drained but we still have mosquito species in SE England that are capable of transmitting malaria. Currently, the parasites cannot survive in the mosquito over winter and a human host is required to sustain the transmission cycle. But if temperatures continue to rise, then all the elements are in place to see a return of seasonal Plasmodium vivax to the Kent marshes.

Of more immediate concern for the UK is the increase in “arboviruses” (arthropod-borne viruses) already happening close to home. There were 1133 West Nile Virus cases (with 92 deaths) reported in Europe last year, most of which were locally acquired infections. We have migratory birds that could import the virus into the UK, and we also have potential vectors in Culex pipiens molestus and the recently introduced Culex modestus. The virus has not been recorded in the UK, but UKHSA reports the level of risk as “high”.

Another mosquito recently introduced to the UK is Aedes albopictus, a vector of Dengue, Zika, and Chikungunya. In 2022 there were 71 cases of Dengue acquired in Europe (the same number as was recorded in the previous 11 years) and 65 of these were in France. Chikungunya and Zika have also been locally acquired in France, where the vectors are present local transmission can occur via imported infections.

Agatha Saez

Healthcare Scientist Team Manager and Quality Lead

UK NEQAS Parasitology

Malaria was once endemic in the US, as it used to be in the UK, and mosquitoes capable of transmitting malaria are still present in parts of both, so occasional cases of reintroduction are possible. Intensive surveillance and control measures have been put in place there and the risk of long-term establishment of malaria in those areas is very low, but these cases illustrate how malaria is capable of reappearing in countries where it was eradicated.

Malaria transmission depends on climatic factors and the level of imported malaria relates to travel habits, especially destination and duration of visit. The possibility that there will be onward spread by local transmission depends on the presence of capable vectors, the suitability of the climate and environment for the growth and survival of the mosquito vector and malaria parasite, and the suitability of the vector for Plasmodium infection. In addition, the global spread of malaria is compounded by its growing drug resistance.

While malaria continues to threaten health globally it is essential that we maintain reliable diagnostic methods. Microscopy remains the gold standard in clinical laboratories. RDTs offer quick diagnosis, but should not be deployed without microscopy, whilst molecular methods remain the most sensitive and specific. It remains important to use fit-for-purpose diagnostic technique(s), backed up by robust quality management.

Image credit | Istock

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