VietNamNet Bridge – Although Vietnam has seen a downward trend of malaria cases, elimination of the disease faces challenges, including the emergence of a strain that has become more drug-resistant, thus, requiring a longer period of recovery, and an increasing number of cases caused by a less dangerous strain that is, however, more difficult to treat.

Illustrative image (Photo: telegraph.co.uk)

In Vietnam, the first resistance in 2010 was found in the southeast province of Binh Phuoc by malaria researchers from the Ho Chi Minh City-based Oxford University Clinical Research Unit (OUCRU).

Prof Tran Tinh Hien, head of the group, said that resistance to a more dangerous parasite (P. falciparum) carried by mosquitoes had risen among patients to more than 33 percent this year.

The resistance has spread to three additional provinces, including the Central Highlands provinces of Gia Lai and Dak Nong and the south-central coastal province of Quang Nam, added Tran Thanh Duong, Head of the National Institute of Malariology, Parasitology and Entomology.

Duong said he was concerned that the spread would lead to outbreaks, especially in the central and Central Highlands region.

As of August 4, the country this year has recorded one death in Gia Lai Province, and 11,070 incidences of malaria, including 29 patients with malignant malaria, according to the National Institute of Malariology, Parasitology and Entomology.

Although the number of cases fell by 35 percent compared to the same period last year, data shows that there were more incidences of malaria resistant to drugs.

Duong says that increasing temperatures and rainfall in the central region provide a favourable environment for mosquitoes infected with these parasites.

Residents in Cuu Long (Mekong) Delta and northern region often travel to areas with high risks of malaria in the centre and Central Highlands to exploit wood or cassava.

When they return home, they can transmit the disease to their relatives and neighbours.

Duong said that anyone who works in these areas should take preventive methods such as sleeping under a mosquito net and wearing long clothes.

Hien also said that only 20 percent of people who have malaria parasites in their blood have symptoms of malaria, such as high fever.

To detect malaria infection, Hien and his colleagues at the OUCRU use a specialised method that is more effective than blood smears.

Hien said the OUCRU had visited Binh Phuoc province, urging residents to have their blood tested, but only a few had done it, creating a major challenge in malaria elimination.

He said that the World Health Organisation (WHO) recommended Artemisinin-based combination therapy (ACT) as the first-line treatment for uncomplicated malaria caused by P.falciparum.

The ACT helps clear all parasites in malaria patients' blood in three days of treatment.

However, in many parts of the world, the parasites have developed an increased resistance to a number of malaria medicines. When the parasites become resistant, they still are in the blood after three days of treatment.

Hien said a study on the spread of malaria in Asia and Africa published in the New England Journal of Medicine in late July showed that a genetic change in the parasites had caused the increased resistance.

The other challenge in malaria elimination in Vietnam is the higher proportion of P. vivax of the total number of malaria cases in the country, Hien said.

He added that the proportion of P. vivax malaria accounted for 60-70 percent of the total malaria cases in the year's first six months in the areas where his team has been conducting clinical trials.

In the past, the proportion was only 40-30 percent of the total, he added.

In the entire country, the proportion last year was 38-55 percent, a jump from nearly 25 percent in 2010, according to the National Institute of Malariology, Parasitology and Entomology.

Although the P. vivax parasites are less virulent than the deadliest P. falciparum, they can occasionally lead to severe complications such as coma, acute kidney injuries or severe anemia, especially in children.

Hien said that it was more difficult to complete a radical cure for patients with P. vivax malaria because of the patient's poor compliance with the 14-day treatment regimen (with primaquine, the only drug that can cure P. vivax malaria).

The vivax malaria can lead to recurrent episodes of high fever because of the stage in the life cycle of the P. vivid parasite, which can lie dormant in infected liver cells for months or even years, and then unexpectedly wake up and provoke a relapse.

"It reduces their quality of life," added Hien.

VNA/VNN