Dr Balvinder Singh Gill, PhD

Disease Control Division

Ministry of Health Malaysia

VECTOR BORNE DISEASE SURVEILLANCE IN MALAYSIA

TYPES OF VECTOR BORNE SURVEILLANCE SYSTEMS

TYPES OF VECTOR BORNE SURVEILLANCE SYSTEMS

Disease Trends

Cases vs Deaths

Notifications (suspected) vs Registered (Confirmed) vs Hospital admissions

Case confirmation

2008 – 49,355 cases

2012 - 21,900 cases

2013 – 43,346 cases

2014 – 108,698 cases

2015 – 89,744 cases(upto 26 September - Week 38)

DISEASE TRENDS - REGISTERED DENGUE CASES IN MALAYSIA BY YEAR, 1973 - 2015

CASES VS DEATHS - DENGUE CASES AND DEATHS IN MALAYSIA, 2000 - 2015

DENGUE CASE NOTIFICATION AND REGISTRATION IN MALAYSIA, 2009 - 2013

DENGUE CASE NOTIFICATION, REGISTRATION AND ADMISSION IN MALAYSIA, 2009-2011

Laboratory diagnosis of DENV infection can be made by serological and molecular methods for the detection of the viral antigen, or antibodies.

Various approaches used in dengue diagnosis are dependent on the timing of sample collection with respect to symptoms and development of immune responses during the course of the infection

LABORATORY DIAGNOSIS OF DENGUE

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In 2012, day 4 was highest with 4,502 (20.6%) cases notified. By Day 5 from the onset of symptoms, 72.4% of cases were notified.

DAYS BETWEEN ONSET AND NOTIFICATION OF DENGUE CASES IN MALAYSIA, 2012

From Day 1 to 4 from the onset of symptoms, NS1-ELISA had a total of 173/306 (56.6%) positive cases compared to 108/306 (35.3%) for

IgM-ELISA. This accounted for an additional 65 (21.2%) positive cases.

However from Day 5 onwards, IgM-ELISA was higher with 81/203 (39.9%) positive cases compared to 55/203 (12.8%) for NS1-ELISA,

this accounted for an additional 55 (27.1%) positive.

EVALUATION OF DENGUE DIAGNOSTIC METHODS IN MALAYSIA, 2010

There were a total of 27 samples tested positive for chikungunya and 10 samples that were tested positive for Leptospirosis.

Hence, of the total samples tested, 29.2% samples were positive for dengue, 9.2% were positive for Chikungunya and 3.4% were positive

for Leptospirosis. 58.2% were negative for any of the tests conducted.

DISTRIBUTION OF DENGUE, CHIKUNGUNYA AND LEPTOSPIROSIS IN MALAYSIA, 2010

DENGUE CASE NOTIFICATION AND REGISTRATION IN MALAYSIA, 2014 – 2015

TYPES OF VECTOR BORNE SURVEILLANCE SYSTEMS

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CIRCULATING DENGUE SEROTYPES IN MALAYSIA, 1990 – 2010

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DENGUE CASES AND CIRCULATING SEROTYPES IN MALAYSIA, 2013 - 2015

DISTRIBUTION OF DENGUE SEROTYPES IN MALAYSIA, 2005 - 2010

TYPES OF VECTOR BORNE SURVEILLANCE SYSTEMS

DENGUE CASES AND PREMISES INDEX IN SINGAPORE, 1966 - 2005

TYPES OF VECTOR BORNE SURVEILLANCE SYSTEMS

There were a total of 27 samples tested positive for chikungunya and 10 samples that were tested positive for Leptospirosis.

Hence, of the total samples tested, 29.2% samples were positive for dengue, 9.2% were positive for Chikungunya and 3.4% were positive

for Leptospirosis. 58.2% were negative for any of the tests conducted.

DISTRIBUTION OF DENGUE, CHIKUNGUNYA AND LEPTOSPIROSIS IN MALAYSIA, 2010

TYPES OF VECTOR BORNE SURVEILLANCE SYSTEMS

Monthly climate readings (rainfall (mm), mean temperature (°C), and average relative humidity (%))

collected from the 26 meteorological stations for the study period were converted from points into

surfaces that matched notification rates within the boundaries.

The inverse distance weighted (IDW) method was used to interpolate metrological data to obtain

values of these climate variables for the states studied.

The raster surface was layered on the geospatial shape files with the state boundaries and the

average value for all raster cells within the state boundary was calculated for each climate variable.

DENGUE – CLIMATE FACTORS

DENGUE – CLIMATE FACTORS - RAINFALL

In states of the west coast, peaks of dengue notification rates were generally seen in the months of

January and February which coincides with the NEM from November to March, while secondary peaks

were also seen during July to August, which in turn coincides with the SWM from May to September.

States in the west coast

Results of cross-correlations shows a negative relation between rainfall and dengue rates during the

current month and a positive cross-correlation was observed after a months lag for most states.

DENGUE – CLIMATE FACTORS - RAINFALL

States in the west coast States in the east coast

Heavy rains have a negative effect by flushing out of larval habitats of these mosquito vectors.

In addition, heavy rains accompanied by strong winds might disturb the flight activity of mosquito

vectors, resulting in difficulties to find hosts and suitable breeding sites, in turn decreasing the disease

activity.

This delay of a month between peak rainfall and the increase of dengue rates can be explained by the

time taken for the development of a mosquito larva, and the transmission cycles of the virus:

DENGUE – CLIMATE FACTORS - RAINFALL

Gubler DJ, Rosen L. A simple technique for demonstrating transmission of dengue virus by mosquitoes without the use of vertebrate hosts. American Journal of Tropical Medicine and Hygiene.

1976;25(1):146-50.

DENGUE – CLIMATE FACTORS - TEMPERATURE

A positive association between temperature peaks and dengue notification rates were seen at several

periods in the west coast states of Selangor and Negeri Sembilan.

States in the west coast

DENGUE – CLIMATE FACTORS - TEMPERATURE

These associations were strengthened by results of cross-correlations that demonstrated a positive

correlation between dengue notification rates and temperature at the current month for states in the

west coast.

States in the west coast

Focks DA, Haile DG, Daniels E, Mount GA. Dynamic life table model for Aedes aegypti (Diptera: Culicidae): simulation results and validation. Journal of Medical Entomology.

1993;30(6):1018-28.

Warmer temperatures contribute to increased adult mosquito survival

THE ECOLOGY OF DENGUE - TEMPERATURE

DENGUE – CLIMATE FACTORS – RELATIVE HUMIDITY

No clear pattern or similarities emerged in on the effect of relative humidity on dengue rates in any of

the states in this study.

THE CLIMATE AND DENGUE

TYPES OF VECTOR BORNE SURVEILLANCE SYSTEMS

DENGUE CASE NOTIFICATIONS AND REGISTRATIONS SOUTHERN STATES, 2011 – 2014

DENGUE CASE NOTIFICATIONS AND REGISTRATIONS CENTRAL STATES, 2011 – 2014

DENGUE CASE NOTIFICATIONS AND REGISTRATIONS WPKL AND SELANGOR, 2011 – 2013

DENGUE CASES JOHOR AND SINGAPORE, 2012 – 2013

TYPES OF VECTOR BORNE SURVEILLANCE SYSTEMS

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