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UK Malaria cases increasing as travellers ignore prophylaxis

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Research shows that members of migrant families visiting friends and relatives in Africa and Asia need to be targeted for malaria prophylaxis. Ingrid Torjesen finds out why

A significant rise in the numbers of UK residents travelling to malaria-endemic areas, combined with a failure to use prevention measures, has significantly increased cases of imported malaria in the UK over the past 20 years, according to new research.

Researchers from the Health Protection Agency’s Malaria Reference Laboratory, analysed the latest trends in malaria in the UK between 1987 and 2006 (Smith et al, 2008). They found an increase in the type with the highest mortality rate and a changing pattern of infection that has implications for practice.

Key findings

Between 1987 and 2006, 39,300 cases of malaria were reported to the Malaria Reference Library in the UK. Case reporting provides detailed information, including personal details of the patient and their illness, any prophylaxis taken, and the reason for, and destination and duration of travel.

Researchers who studied this data found the most common type of malaria was the potentially fatal form caused by Plasmodium falciparum (63% of cases); 23% of cases were attributed to Plasmodium vivax and the remainder to Plasmodium ovale (6%), Plasmodium malariae (1.5%) and Plasmodium knowlesi (one case).

The pattern of malaria changed markedly over the 20 years studied. Reports of P. falciparum increased dramatically but those of P. ovale, P. malariae and in particular P. vivax declined. Almost all P. falciparum (96%) was acquired in Africa, while most P. vivax was acquired in South Asia (80%).

Who is infected?
Travellers visiting friends and relatives in Asian and particularly African countries, from which their family originally migrated, accounted for 64.5% of cases of malaria seen in the UK between 1987 and 2006.

More than two-thirds (67%) of all cases followed travel to West Africa, in particular Nigeria and Ghana. Three-quarters of people who acquired malaria in West Africa had ethnic roots there and had been visiting friends or relatives.

There were 183 malaria-related deaths over the 20 years studied. The risk of death was lower for people who had travelled from the UK to visit friends and relatives in their family’s country of origin than it was in people who had travelled for other reasons.

Use of prophylaxis
Only 42% of the travellers who acquired malaria had taken a form of chemoprophylaxis and people who had visited friends and relatives in their country of ethnic origin were the least likely to have done so.

Among cases in people who had travelled to sub-Saharan Africa between 1999 and 2006, a period during which consistent recommendations on prophylaxis had been made, only 7% of those visiting friends or relatives had taken the recommended drugs compared with 24% of people travelling for other reasons.

Geographical patterns
Cases of malaria follow a striking geographical pattern in the UK, reflecting the areas where first and second generation immigrant groups have settled. It was found that 41% of all cases of malaria, and 65% of cases of P. falciparum malaria, occurred in London, whereas 68% cases of P. vivax were reported in other regions, especially the West Midlands.

P. falciparum cases peaked in January and September, mirroring patterns of travel to African destinations where transmission of P. falciparum occurs throughout the year. For P. vivax there was a summer peak, paralleling the peak transmission periods of malaria in much of India and Pakistan.

Over the 20 years studied there was a significant decrease in the amount of malaria acquired from South Asia, despite increased travel to the area. This may reflect a reduction in the risk of exposure to malaria while in South Asia, with travellers staying in more urban settings where local malaria control measures have been most effective.

Context

Malaria is endemic in 105 countries and causes considerable morbidity for UK travellers who acquire it (Zuckerman, 2008). It is the tropical disease most commonly imported into the UK and there are 1,500–2,000 cases reported each year, with 10–20 deaths (Lalloo et al, 2007). However, the disease is largely preventable if travellers are given advice on how to avoid being bitten by mosquitoes and offered appropriate chemoprophylaxis before they leave the UK.

The increasing accessibility of international air travel means more trips are being made to regions where malaria is endemic. In the past decade, there has been a 150% increase in trips made by UK residents to endemic areas (Zuckerman, 2008).

The continued influx of migrants to the UK also means many trips are not made by tourists but by travellers returning to their family’s country of ethnic origin to visit friends or relatives.

Implications for nurses

The researchers say the disproportional burden of malaria in ethnic groups visiting friends and relatives, particularly in West Africa, offers a golden public health opportunity for nurses. Health messages about the need to protect against malaria through avoidance of mosquito bites and use of chemoprophylaxis are obviously not reaching high-risk groups.

People visiting friends or relatives in their family’s country of origin were least likely to use chemoprophylaxis, which is a concern as they are more likely to go to remote areas where there is a higher risk of transmission than in tourist areas.

There is some evidence that people visiting friends or relatives are less likely than tourists to seek travel health services before departure, less likely to initiate chemoprophylaxis before they travel, and less likely to adhere to preventive measures while abroad (Smith et al, 2008).

This may be due to the cost of buying the recommended chemoprophylaxis and fears of side-effects. Purchase of inappropriate over-the-counter prophylactic drugs or inexpensive (and sometimes counterfeit) prophylaxis at the destination adds to the problem (Zuckerman, 2008).

In addition, people visiting friends and relatives in endemic regions often underestimate the risk. Some of those born in Africa who moved to the UK believe they have some protection against the severe consequences of malaria and that malaria is a trivial complaint (Smith et al, 2008).

This belief that people born in malaria-endemic regions are already protected against the disease needs refuting. Not only do people of African origin contract malaria, they are at much higher risk than other travellers to Africa.

Children account for 14% of cases of malaria in the UK, which is much higher than would be anticipated. This is probably the result of completely susceptible UK-born children accompanying their overseas-born parents on visits to family and friends in endemic areas (Lalloo et al, 2007).

The findings highlight the need for nurses to be aware of malaria symptoms and for those involved in travel health to focus their preventive efforts on migrants and their descendants planning a trip to visit relatives in their country of ethnic origin.

Nurses should be aware of the potential symptoms of malaria and question suspect cases about their travel history (see box).

Conclusion

This study highlights the need to focus tailored messages on preventing malaria on members and descendants of migrant families visiting friends and relatives, especially those from Africa. The UK guidelines recommend all UK residents, irrespective of country of birth, use effective malaria prophylaxis when visiting highly endemic areas. If the amount of malaria attributable to people of African descent visiting friends and relatives was halved, it would cut the malaria burden in the UK by almost a quarter.

Symptoms of malaria

  • The symptoms of malaria are very similar to those of flu, so malaria should be considered in anyone with a fever or history of fever who has visited a malaria-endemic region in the past year, regardless of whether they took prophylaxis.

  • Symptoms include – a flu-like illness, fever, shaking, headache, muscle aches, tiredness and generally feeling unwell. Nausea, vomiting, diarrhoea and other gastrointestinal disturbances may also occur. Jaundice or respiratory symptoms occur occasionally and sometimes confusion or seizures in missed P. falciparum infections.

  • Children are less likely than adults to complain of chills, aches and pains or headaches and more likely to present with non-specific symptoms of fever, tiredness, gastrointestinal symptoms and feeling generally unwell.

  • The minimum incubation period is six days. Most patients with P. falciparum present in the first month and almost all within six months. P. vivax or P. ovale infections may take years to present.

  • Most missed malaria is confused with viral infections, influenza, gastroenteritis or hepatitis.

Source: Lalloo et al (2007)


References

Lalloo, D.G. et al (2007) UK malaria treatment guidelines. Journal of Infection; 54: 111–121.

Smith, A.D. et al (2008) Imported malaria and high risk groups: observational study using UK surveillance data 1987–2006. British Medical Journal; 337: a120.

Zuckerman, J.N. (2008) Imported malaria in the UK. British Medical Journal; 337: a135.

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