PCR and Culture Identification of Pathogenic Leptospira spp. from Coastal Soil in Leyte, Philippines, after a Storm Surge during Super Typhoon Haiyan (Yolanda)

Abstract

e Leptospirosis is a zoonosis caused by pathogenic Leptospira spp. Most of the outbreaks of leptospirosis occur after floods caused by heavy rain in countries where Leptospira spp. are endemic. It has been believed that the overflow of seawater rarely causes outbreaks of leptospirosis because the leptospires are killed by salt water. On 8 November 2013, a storm surge caused by Super Typhoon Haiyan (Yolanda) inundated the entire coastal areas of Tacloban and Palo in Leyte, Philippines. The present study was carried out in order to determine whether the environmental leptospires in soil were able to survive after the storm surge in the affected areas. We collected 23 wet soil samples along the coastal areas of Tacloban and Palo 2 months after the storm surge. The samples were suspended in HEPES buffer, and the supernatants were cultured in liquid or semisolid Korthof's medium supplemented with five antimicrobial agents to inhibit the growth of contaminants. Leptospires were isolated from primary cultures of 22 out of 23 samples. The DNA of pathogenic Leptospira species was detected in 11 samples (47.8%) by analysis of flaB by nested PCR. Eventually, two pathogenic Leptospira strains were isolated and showed the highest 16S rRNA gene sequence similarity to Leptospira kmetyi. When these isolates were experimentally mixed with soil, they were found to survive in seawater for 4 days. These results show the possibility that leptospires living in soil survived after the storm surge. Our findings may serve as a warning that when seawater inundates the land during a storm surge or a tsunami, an outbreak of leptospirosis could occur in the disaster-stricken area.

Leptospirosis in the Tohoku Region: Re-emerging Infectious Disease

“…The DNA of the pathogenic Leptospira was confirmed in the soil of the coastal area in the Philippines after a storm surge, indicating that the soil can be a breeding ground for Leptospira during a disaster and the agents can survive in seawater (Saito et al 2014). Although historical huge tsunami hit the east coastline of the Tohoku region in March 11, 2011, the patients of leptospirosis were not found (National Epidemiological Surveillance of Infectious Diseases (NESID)).…”

Potentially Pathogenic <i>Leptospira</i> Species Isolated from a Waterfall in Thailand

“…Of these, 5 isolates (5 17, 29 ) were found to be closely related to L. alstonii with 99 to 100 identity, whereas 1 isolate (1 17, 6 ) is closely related to L. kmetyi, with 99 identity. The presence of L. alstonii and L. kmetyi in the environment has been reported in many countries (7)(8)(9)(10). Recently, L. alstonii was isolated from greater white toothed-shrews in Ireland (11) and from an asymptomatic cow in a slaughter house in Brazil (12).…”

Development of Point-of-Care Testing for Disaster-Related Infectious Diseases

“…It was suggested that leptospires are ubiquitous in the Philippines and are soil bacteria. Based on the results of this recent study, it was hypothesized that soil serves as an important reservoir of pathogenic Leptospira spirochetes, which may cause outbreaks of leptospirosis during floods caused by typhoons and/or heavy rains (Saito et al 2014). Therefore, it is expected that walking through mud without protective footwear (for example, during farm work, water-based recreation, or wading after a flood) would place a person at high risk for acquiring infection with Leptospira.…”