Northern Mexico is still grappling with a mysterious meningitis outbreak after state officials reported another fatality due to the condition on Monday, bringing the total number of deaths to 35.

Specific details about the latest death amid the outbreak weren’t immediately available, but health authorities in Mexico’s rural Durango state have documented 79 cases so far, Reuters reported.

The outbreak has been going on for a few months, with the first case being reported late last year after doctors diagnosed several patients with aseptic meningitis — a serious inflammation of the brain that is said to be rarely fatal in healthy people with normal immune systems, as per the Texas Department of State Health Services.

Data relayed by local officials to the World Health Organization (WHO) indicated that infected patients in Durango had surgeries using spinal anesthesia in private hospitals.

The outbreak seemed to have spread more in the region as Durango health authorities reported new cases, hospitalizations and fatalities nearly every day this year, according to the New York Post. The Mexican health ministry did not immediately respond when asked for comment on the issue by the outlet.

Durango’s state government called the outbreak “an unprecedented situation” on its website and emphasized that officials at all levels were working together to address the problem and help provide the best treatments for patients, as per Reuters.

In November, prosecutors in northern Mexico blamed the private hospitals for allegedly using contaminated anesthetics that triggered the meningitis outbreak. Seven arrest warrants were issued against the owners and directors of four private hospitals at the time, ABC News reported.

A month after, WHO said it would help Mexico’s health ministry and local authorities investigate and monitor the mysterious meningitis outbreak.

Meningitis is a medical condition characterized by the inflammation or swelling of the protective membranes covering the brain and spinal cord. This is often caused by a bacterial or viral infection. However, injuries, certain drugs, cancer and other types of infections were also found to cause meningitis. Treatment differs depending on the cause of the condition, according to the Centers for Disease Control and Prevention.

Bacterial meningitis
About 4,100 cases of bacterial meningitis, including 500 deaths, occurred each year between 2003 and 2007 in the U.S., according to the CDC. Creative Commons