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A. Background
 An Epizootic which is defined as the
occurrence of a disease in crows’ population with the frequency of mortality
in clear excess of normal expectancy was reported to occur in Noonu Kendhikulhudhoo island
and neighbouring islands, since 28 December 2004 after the Tsunami.
DG-HS, MOH, Dr. Abdul Azeez
Yoosuf requested WHO’s technical support for a
complete investigation of the situation. With a presumptive diagnosis of West
Nile Fever which is known to affect birds and can cause a potentially serious illness in
humans, field investigation was undertaken.
WNV is a seasonal epidemic in North
America and other part of the world that flares up in the summer
and continuous into the fall. Most often WNV is spread by the bite of
infected mosquito (Culicoides). Mosquitoes are WNV
carriers that become infected when they feed on infected birds, infected
mosquitoes can then spread WNV to human and other animals when they bite. In
a very small number of cases WNV has also been spread, for examples through
blood transfusions, organ transplants, breastfeeding and even during pregnancy
from mother to baby, but the risk is very low, and should not prevent people
from having it.WNV is not transmitted through
casual contact such as touching or kissing a person with the virus. The
incubation period between 3 and 14 days. Only one out of 150 people
infected with WNV will develop severe
illness, the severe symptoms may include high fever , headache, neck
stiffness, stupor, disorientation, coma, tremors ,convulsion , muscle
weakness, vision loss, and neurological effects may be permanent.
Approximately about 80 % of people (about 4 out of 5) who are infected with
WNV will not show any symptoms at all, and up to 20 % of the people who
become infected will display symptoms. There is no specific treatment for
most virus infection so is WNV. In milder cases, peoples experience symptom
such as fever, aches that pass and improve on their own, no need to seek
medical attention. Only severe WNV illness usually requires hospitalization.
With this background information, DG-HS
decided to take immediate investigation and preventive measures. A team
consisting of an Epidemiologist, a laboratory technician, VBDCU Program
Manager was dispatched to the affected island with the following tasks:
 Investigation of the dying crows
Collection of blood samples from the febrile
cases
Collection of dying crow samples
Fogging the whole affected islands with malathion spraying for vector control
B. Study Population
Four islands who were reporting the occurrence
of dying crows were visited: Kedhikulhudhoo
(I), Hebadhoo (I), Kudafari
(I) and Maafaru (I).
The
islands belong to NoonuAtoll. Atoll is defined as “ a ring shaped “ coral reef and small island,
enclosing a lagoon and surrounded by
open sea. There are 25 Atolls which are divided into 21 administrative regions
in Maldives. The islands with the height of 0.5 – 1 meter above sea level
characterized with some form of vegetation, trees, bush and grass. There are
an estimated 1190 islands in the country, this total number can change from
time to time as the islands are continually eroded and washed away, while new
islands are being formed, of this total only 200 inhabited islands.
C. Methods and
materials
First reported by island chief of Kedhikulhudhoo (I) in 28 December 2004 two days after tsunami, an outbreak
of “dying crows” in the island.
The remoteness of the outbreak area precluded
a timely or complete assessment of outbreak. In response to reports of an
outbreak of dying crows, WHO and national health authorities organised an investigation.
Departed form Male’ on thursday
evening, of 06 January 2005, and arrived
Kedhikulhudhoo (I) on 08 January 2005 morning
11.00 hrs, the next days all affected islands were visited. Arrived Male on 11 January 2005 afternoon 14.00.
Case definition developed (established):
Human:-
People
with fever in the period between 28 December 2004 to 09 January 2005.
Crows:-
The
dying crows
Blood samples were collected from febrile
cases (5cc from each febrile case for virus isolation and serological tests)
Only dying crows were taken for samples for
virus isolation
Seven dying crows were caught from three
islands and killed and put them into plastic bags and stored in the cold box.
Five blood samples were taken from 12
outpatients in Kedhikulhudhoo (I) clinic, five blood samples were taken from Hebadhoo (I) , and five blood samples from
Maafaru (I).No febrile cases were found
in Kudafari (I ). Both blood samples and
animal samples (crows) were stored at -20 degrees centigrade in the vaccine
cold box with dry ice. On arrival, both blood and animal samples were
transferred and stored at IGMH laboratory cold storage.
Samples of crows consisting of brain( one sample ), liver ( three samples
) and cloaca
( one sample ) biopsies were collected , ( biopsy was done at IGMH laboratory on 12 January 2005 as per adviced in the preliminary report of 11 January 2005 ).
Both animal and human blood samples was sent to WHO/SEARO via DHL for further
virus isolation and serological testingfor vector borne as well as for air borne/aerosol borne
viral diseases of outbreaks potential. Blood samples were sent to Pune Institute of Virology, India,
and animal samples were sent to Australian Animal Health Laboratory (AAHL), Geelong Australia.
Line listing of reported febrile cases was
made consisting of name of cases, date of report, date of onset, sign and
symptoms, age, sex, specimen taken.
Relevant identifying and demographic
information were also collected.
Results
Epidemiological
findings
The outbreak area of
dying crows is located in four islands: Kedhikulhudhoo
(I), Hebadhoo
(I), Kudafari
(I) and Maafaru(I).
By
the time the investigation team left Maafaru (I) ,
there is an information that the neighbouring
island starts reporting dying crows.
Decomposing
crows seen on the beaches of the islands. Some of dead crows were buried by
the people of the islands. Most of the people on the islands were exposed to
the dead and dying crows.
The
dying crows are showing signs and symptoms as follows:
excrete and discharge from the eyes and nose, bloody
diarrhea, (discharge) from cloaca. Some dying crows , were blind. No other bird species involved in the
outbreak.
No
fever cases were found in Kudafari (I) . No rash and neurologic
signs and symptoms found among fever cases.
No
damage were seen on four islands due to tsunami.
Only minor damage seen such as dead trees (bread fruit, banana and guava) in Kudafari (I) island ,the
water level was estimated 1.5 meters and stayed for about 5 minutes. People
in the four islands were healthy and happy.
Rumour spread in the community that the crows were
poisoned in neighbouring island, because the crows
were damaging the water melon plantation. But this rumour
has yet not been proved.
Till
20 January 2005, the two islands ( Kedhikulhudhoo (I) and Kudafari (I) ) are still reporting the
dying crows, with decreasing trends .Five crows were reported dying from Kudafaree on 15 January 2005.Of to day the 17 February
2005, by the time the report being up dated, there has been reports of more
death crows, now in islands in the
Central region of the country, thus far away from the place they were
occurring first after the tsunami. (Include the status of the last update as
on report date..)
Lab investigation findings
All 15 human blood samples sent to Pune Institute of Virology WHO CC ,
India for
serologic testing for known human virus infections , the result were negative for West Nile Virus ( WNV ) ,
Avian Influenza ( AI ), and for JE.
For animal samples sent to Australian Animal
Health Laboratory (AAHL), Geelong
Australia,
molecular diagnosis, TaqMan real time for PCR
specific for Avian Influenza (AI) and TaqMan real
time PCR specific for West Nile Virus (WNV) was performed on nucleic acid
extracted from all 6 samples associated with SAN 05 – 0085. Result (per 25 -
January – 2005), AI and WNV were not detected from any of the samples.
Conventional RT - PCR for Nelson Bay
virus and Broom virus were done on first passage (Vero cells) samples of
liver and cloaca. Result per 11 February 2005 was negative for Nelson
Bay virus as well as for Broome
virus. For virus isolation, on 24 –
January 2005, the specimens have been inoculated into eggs and
onto cell cultures, results are still pending. In 28 January – 2005, the
specimens have also been inoculated into Vero cells. Syncytial
CPE observed in monolayers inoculated with specimen
no.4 ( liver ), and specimen no.6 ( cloaca ) by day
3 and specimen no.3 ( liver ) by day 4.Cell material and supernatant then sent for Electron
Microscopic ( EM ) examination .Virus particles were visualised,
and the virus ultra structure is indicative of the Family Reoviridae
and Genus Orthoreovirus.The material has been
inoculated into Vero cells for the
second time. Virus characterisation techniques are
on going.
Hence the report is based on virus isolation and
electron microscopic characterization, indicate presence of reoviruses. The final confirmation report
shall be available shortly. This virus is not a usual pathogen to human
beings but has been responsible for similar deaths in crows in Canada in 2004 and at several locations
from east to west across the United States in 200.This virus is being
considered as an emerging disease of crows.
Public health measures
House to house spraying was done in four islands using
ULV (Ultra Low Volume) and swing fog machines. Insecticide used was malathion. Bush
surrounding houses were also sprayed. Dying flies and mosquito seen right
after fogging, showing that fogging was very effective in killing the
insects, however post spraying entomological evaluation need to be done for
more scientific evidence.
Discussion
Through history the occurrence of disease and similar
deaths in crows population with such signs and
symptoms with the frequency of illness or mortality clearly in excess of
normal expectation have never been reported to occur in Maldives. Once in a while crows were
considered as pests and were hunted and killed by the farmers.
The myth of epidemics and plagues are inevitable after
every disasters has drawn the attention of peoples during complex emergency
such as in tsunami disaster, in reality in most of the time, epidemic do not
spontaneously occur after disaster and dead bodies will not lead to catastrophic outbreaks of
exotic diseases. The key to preventing disease is to improve sanitary
conditions and educate the peoples.
The worries about the possibility of West Nile Virus
transmission in the islands is understandable, since birds are a source of
mosquito infection for West Nile Virus, and
West Nile Virus (WNV) is a potentially serious illness, is established
as a seasonal epidemic in North America and other part of the world. With the
shrunken world due to better mode of transportation it is not unlikely that
WNV can be introduced to other parts of the world. The immediate decision made
by DG-HS, MOH to send a team to investigate the outbreak of dying crows of
unknown origin in the islands and provides immediate appropriate public
health action is of paramount importance to minimize the consequences of
possible outbreaks of human cases due to vector borne viral diseases such as
WNV.
It is evidence that from the virus isolation and virus
characterization in the laboratory indicate the presence of reoviruses which is not a usual pathogen
for human being. No WNV and AI involved in the outbreak , even though , care
and alert should be maintained for possible outbreaks of anthropozoonosis
( diseases acquired by humans from other vertebrates experiencing enzootic or
epizootic ) in near future.
Recommendations
Lab examination should be directed not only to
arthropod borne viral diseases as well as aerosol borne viral diseases , but it should also be directed to possible
chemical poison.
Strengthen the laboratory capacity of MOH, Maldives
with sufficient equipment and skilled manpower to fulfil
the specific needs of Maldives
to support Integrated Surveillance
System.
Veterinarian is now very much needed to
anticipate the potential outbreaks of Epizootic and Zoonotic diseases in the
near future in the country.
So far fogging and spraying were done without
proper entomological evaluation. Trained
entomologist is
needed indefinitely. The occurrence of vector borne diseases in the islands
will damage the tourism industry in the country. Preventive measures should
be undertaken immediately .
Even though areas with the highest prevalence
of avian influenza were not directly
affected by tsunami, however,
the risk of importing avian influenza can be minimized by controlling the
movement of poultry from areas where outbreaks of avian influenza have
occurred. It is important to ensure that infected poultry are kept out of the
food chain, including emergency food relief activities.( Note : WHO has received informal report of two
additional cases of H5N1 infection in Vietnam, if confirmed these will bring
the total in Vietnam, since mid December 2004, to six cases. Of these, four
have died ).
The existing disease recording reporting
system in Maldives
is good enough, there is a need to assign epidemiologist to organize and
analyze the surveillance data for evidence based decision making process. This will allow the
detection of early warning signals of potential diseases outbreaks, monitor
diseases of public
health importance, and ensure MOH capacity to investigate and respond to
emerging threats through provision of
timely information and appropriate immediate public health action.
Improve and increase community awareness
toward prevention of communicable diseases
in general, specifically for vector borne diseases, through health promotion program activities,
and organize their active participation in source reduction.
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