Journal of Mosquito Research 2015, Vol.5, No.17, 1-10
3
(March - May). Snowfall occurs between January and
March within the upper and lower Himalayan ranges.
Temperature and rainfall:
Monthly maximum,
minimum, and average temperatures and rainfall data
of Uttarakhand were collected from Indian Meteorological
Department. In this article, we have included the
temperature and rainfall data of Nainital and Dehradun
districts only, as entomological surveys were carried
in these two districts only. Temperature and rainfall
data based on mean of the last 25 years (monthly
arithmetic averages) are presented graphically in the
result section.
Population:
The Uttarakhand has a population of
approximately 10,116,752 inhabitants. Nainital and
Dehradun are having an estimated population of
955,128 (494,115 males and 461,013 females) and
1,698,560 (893,222 males & 805,338 females)
inhabitants respectively (data source: Census India)
(data source: Census of India 2011).
Dengue fever and Epidemiological data
collection
We worked in collaboration with the Department of
Health, Govt. of Uttarakhand for this study. The dengue
case definition was adopted as per the recommendation of
World Health Organization Regional Office (Southeast
Asia Regional Office 1999). Only the serologically
confirmed dengue cases, diagnosed using Rapid
Detection kit (NS1 Ag Ab Combo) and enzyme-linked
immunosorbent assay in 2010 by different sentinel
laboratories of the Department of Health, Govt. of
Uttarakhand were included in the analysis reported
here. All duplicate notifications were removed before
analysis. We have also tried our level best to identify
cases with a history of travel within 10 preceding days
of the onset of illness to states where dengue also
occurred were classified as imported and were not
included in the analysis. We have collected the
epidemiological report of dengue cases in Uttarakhand
for the last five years (2006 to 2010) from the
Department of Health, Govt. of Uttarakhand. During
epidemic in 2010, suspected cases were identified and
a sero-epidemiologic survey was conducted in
Nainital and Dehradun districts through state health
services for laboratory-confirmation of suspected
cases. The denominator for the calculation of total and
sex wise incidence rates of reported indigenous cases
of dengue were based on the estimated mid-year total
population and male/female population obtained from
the Office of Registrar General and Census Commissioner
(Uttarakhand State), India.
Entomological Surveillance
We have chosen 11 localities each in Nainital and
Dehradun as mentioned above for entomological
survey. In these areas, we surveyed all potential
breeding sites in monsoon and post-monsoon months
from September to November 2010, immediately after
confirmations of an early outbreak of dengue in
August 2010 with 19 confirmed dengue cases. All
non-hermetically closed containers containing any
volume of water were considered as potential breeding
sites. All water-holding containers were examined.
Either the name/type of the containers (viz. Tire,
cooler, fridge etc.) or construction materials (viz. Tin,
cement tank, clay pots, and plastic container)
classified the breeding sites. We recorded the number
of houses inspected, positive containers (with
Aedes
pupae or larvae) and houses with ≥ 1 positive
container.
Statistical Analysis
For all statistical analysis, we performed Kolmogorov-
Smirnov (with Dallal- Wilkinson-Lilliefor
P
value),
D'Agostino & Pearson Omnibus and Shapiro-Wilk
normality test to see whether the data follow a
Gaussian distribution and implemented appropriate
statistical tests and calculated the corresponding
P
values. We calculated the total as well as sex wise
incidence rates of reported indigenous cases of dengue
(combined of Nainital & Dehradun) based on the
estimated mid-year total population and male/female
population respectively. We analyzed larval survey
data of different breeding sites based on the name/type
of the containers (viz. Tire, cooler, fridge, etc.);
construction materials (viz. Tin, cement tank, clay
pots, and plastic container) and three sigma limits
were applied to judge the significance of chance of
getting
Aedes
larvae. The three sigma limits were
applied to alert vector control operation process
regarding potential dangerous container for mosquito
breeding following statistical quality measurement.
For all areas, we calculated different entomological
indices, viz. HI, CI, and BI and performed the
Spearman rank correlation coefficient between the
different indices in all inspected areas. This statistical
