Volume 22, Number 10—October 2016
Letter
Naegleria fowleri Meningoencephalitis Associated with Public Water Supply, Pakistan, 2014
Table
Characteristics of 13 water samples collected from water treatment plant A and its distribution system, including water supplied to the apartment and neighborhood mosque of a patient with primary amebic meningitis, Karachi, Pakistan, 2014*
| Water supply | Sample location | Sample type | Total chlorine, mg/L | Temperature, °C† | Culture positivity for FLAs | PCR results for Naegleria fowleri amebae‡ | Distance relationships of water samples |
|---|---|---|---|---|---|---|---|
| Reservoir§ | Water from Kinjhar | Untreated | ND | 30 | ++ | – | From reservoir to plant A, ≈100 km |
| Water treatment plant A |
Filtration unit¶ | Treatment underway | <0.5 | 29.5 | ++ | – | |
| Plant A exit point |
Filtered and chlorinated |
0.5 |
30 |
++ |
– |
||
| Pumping station# |
Pumping station, site 1 | Filtered and chlorinated | ND | 30 | ++ | – | From plant A to pumping station, ≈11 km |
| Pumping station, site 2 |
Filtered and chlorinated |
ND |
30 |
++ |
– |
||
| Catchment areas: patient’s apartment and neighborhood | Mainline | Filtered and chlorinated | ND | 30 | – | – | From pumping station to patient’s house, 1km |
| Underground boring well water** | Untreated | ND | 28.5 | + | – | Within patient’s house, ≈10 m | |
| Underground tank | Mixed†† | ND | 28 | + | – | Within patient’s house, ≈10 m | |
| Overhead tank | Mixed | ND | 31 | ++ | + | Within patient’s house, ≈10 m | |
| In-house storage tank‡‡ | Mixed | ND | 30 | ++ | – | Within patient’s house, ≈5 m | |
| Bathroom | Mixed | ND | 29 | + | – | Within patient’s house, ≈5 m | |
| Neighborhood mosque | Filtered and chlorinated | ND | 31 | ++ | + | From patient’s house to mosque, ≈100 m |
*FLAs, free-living amebae; ND, not detected; ++, >3 amebae seen with 40x magnification; +, 1–3 amebae seen with 40 x magnification; –, no amebae detected.
†Water temperatures of 25°C–40°C are conductive for flourishing of Naegleria fowleri amebae.
‡PCR was negative for other pathogenic FLAs such as Balamuthia or Acanthamoeba spp.
§Kinjhar Lake, located in Sindh province, Pakistan, is the main reservoir that supplies water to Karachi.
¶The filtration unit was the only site for which 2 samples were taken; only 1 sample was taken from all other specific sample locations.
#Samples were taken from a single pumping station at 2 separate sites.
**Underground wells provide additional water supplies locally known as boring wells.
††Water from these wells is not treated and is mixed with treated water from the main water supply in storage tanks.
‡‡Underground and overhead tanks are shared by >100 households, so for continuous water supply, residents keep small tanks in their homes.