HOUSTON - The US state of Louisiana has in recent weeks seen a rise in cases of West Nile virus, which has caused two deaths.

The Louisiana Department of Health and Hospitals announced on Monday that there has been 21 new West Nile cases in the southern state since last week.

The latest development has brought the total virus cases up to 53, the highest since 2007, according to the department.

It confirmed that recently two Louisianians died from the neuro-invasive West Nile virus, which is the most lethal virus, as it could lead to the swelling of brain and spinal cord, therefore irreparably damaging the nervous system.

In Louisiana, neuro-invasive cases have totalled 29 this week, the highest since 2006 and a huge increase compared to last week's 16.

Meanwhile, Houston sees the West Nile cases rising to seven lately, as the health department said on Monday a middle-aged woman living in southeast Houston was confirmed to have the disease on Friday.

The same day, Dallas County also reported 130 West Nile cases and the seventh deaths.

Since the beginning of this year, the United States has reported 241 cases, with four deaths.

Commonly seen in temperate and tropical regions, the West Nile virus was first identified in 1937 in Uganda, the East African nation in the West Nile sub-region.

The virus mainly infects birds, but is also known to infect human bodies mainly through mosquito biting. Scientists say about 80 percent of infections are symptomless.

The World Health Organization said treatment of this virus often involves hospitalization, intravenous fluids, respiratory support and prevention of secondary infections.