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By
Ngan Chantha,
P. Guyant, S. Hoyer
National Malaria Centre,
372 Monivong Boulevard,
Phnom
Penh,
Cambodia
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Abstract
In January 1998, an unprecedented dry-season outbreak of dengue haemorrhagic fever (DHF) occurred in Phnom Penh. An immediate and adequate
outbreak response quelled the outbreak which was limited to the Capital.
However, the nationwide DHF case figures remained at the normal level
during the dry months of April and May.
After June 1998, the expected sharp increase in the number of
cases occurred: from 807 cases in May, the number grew to 3291 cases in
July. The virus succeeded in spreading to many new
areas, affecting, at the same time, 18 of Cambodia’s 22 provinces as compared to
only six affected during the last epidemic of 1995. The virus had invaded
rural areas down to a population density level as low as
45 inhabitants/km2. Consequently, the population at risk,
which was formerly restricted to urban and peri-urban
areas, had suddenly increased from 1 485 000 to 7 350 000 living in 1 343
000 households.
During 1 January-31 December 1998, 16 215 cases of DHF were
recorded in Phnom Penh’s two children’s hospitals and
the 19 paediatric wards of hospitals in the
provinces affected by the outbreak. The cumulative number of deaths among
these cases was 475. The overall case fatality rate (CFR) of 2.9% in 1998
was lower than the CFR of 4.7% in the previous outbreak in 1995. However,
the CFR in certain provincial hospitals was still very high (10%).
The control operations undertaken by the National Dengue Control
Programme (NDCP) included Temephos application,
ULV spray supported by a strong IEC-based programme
across sectors and donors. DHF treatment and management facilities were
upgraded at several Cambodian Children’s Hospitals and wards with WHO
support.
Keywords:
DF/DHF, Aedes aegypti,
case fatality rate, Temephos, Red Cross,
treatment and management of DHF, Cambodia.
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Introduction
The
first case of dengue haemorrhagic fever (DHF)
occurred in Cambodia in 1962. Since 1980, when 347
cases and 20 deaths were reported, DHF has become a major public health
problem in the country. DHF appears to be cyclic in Cambodia as in other countries in South-East Asia with large outbreaks occurring
every two to three years(1).
The last major outbreak occurred in 1995 when 10 199 cases, with 424 deaths,
were reported in children, giving a CFR of 4.7%.
During
1998, strangely enough, a large number of DHF cases originating in Phnom Penh were diagnosed during the dry
season, a phenomenon recorded for the first time. The number
of cases during the 1995 dry-season outbreak were ten times less, thus
indicating an impending epidemic of high proportion in the coming rainy
season.
Dry-season morbidity – 1998
Beginning
January 1998, a total of 247 cases of DHF were recorded in Phnom Pehn. An immediate epidemic response operation was able
to quell the locally-limited outbreak by March 1998 when the cases receded to
80 and 90 respectively during the dry months of April and May, thereby
showing a reduction of about 55%.
Wet-season morbidity and mortality (1998)
With
the onset of rains in June 1998, a sharp increase in DHF cases occurred
nationwide when the number of cases rose from 807 in May to 4627 in July.
These ultimately touched a figure of 16 216 cases with 475 deaths by December
with a case fatality rate of 2.9%. However, in certain provincial hospitals
CFR was as high as 10%. The monthly DHF figures for the period 1995-1998 are
given in Fig.1. The epidemic spread to 18 of the 22 provinces of Cambodia as shown in Fig.2.
Measures taken for epidemic control
The
following steps were taken in chronological order for the containment of DHF
during the dry season:
 Control of the DHF outbreak in Phnom
Penh (February);
Fund-raising and implementation of epidemic
preparedness measures to counter the nationwide DHF epidemic
(March-May);
 Containment of the expected nationwide DHF
epidemic (June-November);
Development of a sustainable long-term
approach through a comprehensive follow-up project designed with a mixture of
successful vertical and integrated elements for surveillance and outbreak
control, social marketing of new preventive tools; and
Community participation through regular and
effective cleaning-up days (1999-2002).
Concurrently,
the following epidemic preparedness measures were also undertaken:
Development of a nationwide DHF action plan;
Fund-raising;
Strengthening of the clinical case reporting
system;
Setting up of a virological
and immunological DHF disease confirmation network, including the
differential diagnosis of murine typhus, enterovirus 71 and Japanese encephalitis;
Refresher training for staff in hospitals and
hygiene stations in preventive measures in dengue-prone provinces;
Production of TV and radio messages,
reproduction of leaflets and other IEC materials;
Building-up stocks of larvicides,
drugs, and equipment, and their distribution;
Proactive distribution of Abate based on
entomological surveillance;
Peri-focal space
spraying around early cases in conjunction with quarter-wide Abate
distribution; and
Large-scale disitribution
of Abate and space spraying when the epidemic threshold level was reached.
Elements
of "crisis management" of DHF control included fund raising appeal
by Centre national de malariologie (CNM),
coordinated by WHO, stepping in of International Federation of the Red Cross
(IRFC) in a big way in emergency procurement of ULV spraying generators/ pick
up trucks, requisite quantities of larvicide,
distribution in packages of 20 grams (correct dose for a standard Cambodian
jar of 200 litres). Magnitude of the task can be guaged by the fact that 56 tonnes
of Temephos was distributed within three months to
560,000 households, protecting an estimated 2.6 million inhabitants. Most
importantly, the newly set up geographical information system (GIS) for
dengue control proved very helpful in determining the priority areas for control
interventions. (Figure 3). National NGOs, the Cambodian Red Cross, the media
and other sectors actively participated in the control of an epidemic which
had engulfed nearly 82 percent of the country.
Clinical management of DHF cases
The
problems connected with the clinical management of DHF cases were addressed
by despatching three teams of paediatricians
to the provincial hospitals which had the highest case-load and CFR (Battambang, Takeo and Kg. Cham). In addition, medical equipment such as haematocrit centrifuges and paediatric
blood pressure meters were distributed to children’s wards. Sufficient
quantities of IV fluids, plasma expanders and perfusion sets to treat 10 000
children were sent through the courtesy of IFRC. These drugs were distributed
directly by the Red Cross to the paediatric wards
and hospitals which were in greatest need, according to a Joint MoH/WHO contingency plan. The most crowded of the Phnom Penh children’s hospitals, Kantha Bopha, was upgraded,
with WHO support, by adding 100 additional dengue beds. The IFRC provided
disease test kits (HIV/HBV/HCV/VDRL) to these hospitals, which performed up
to 70 blood transfusions each day.
IFRC ever ready to step in for such large scale emergent and
responsive actions.
Long-term strategy for DHF control
On
the basis of the lessons learnt, a long-term strategy for DHF control should
have the following elements:
1. The
early warning system of the national dengue control programme
should be strengthened for early detection and rapid response to prevent DHF
outbreaks.
2. Preventive
actions against vectors (Aedes aegypti) should comprise of regular treatment of jars
with temephos through social marketing which costs
only 7 US cents per household.
3. There
is a need for designing a `jar lid’ which will permit harvesting of rain
water but will not permit Aedes breeding.
4. Some
supportive legislation/law enforcement might contribute to its general
acceptance.
Reference
1. Gratz NG. and Knudson AB.
The rise and spread of DEN/DHF and its vectors, 1996; CTD/FIL/ DEN/96.7.
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