Zika virus infection is transmitted by Aedes mosquitoes, similar to dengue. Only about one in five infections are symptomatic. The disease is usually self-limiting, although rarely, serious neurological complications have been reported. The disease is characterised by fever, rashes, joint pain, muscle pain, headache and conjunctivitis. Most symptoms last for four to seven days. The main vector in Singapore is the Aedes aegypti mosquito.
A total of 458 laboratory-confirmed cases of zika virus infection were reported in 2016 (Figure 3.16). In May 2016, Singapore identified its first imported case of zika virus infection in a traveler returning from Brazil. No further cases were identified for three months. On 22 August 2016, a primary healthcare doctor notified the Ministry of Health of an increase in cases with fever, rash and joint pain in the Kallang-Aljunied neighbourhood. Investigations confirmed the first cluster of zika virus infection.
Out of the 458 cases, three were imported cases, involving two Singapore residents and one foreigner with work permit. The remaining 455 cases were indigenous cases.
Figure 3.16
Weekly distribution of reported zika cases, 2016
The incidence rate among indigenous cases was highest in the 25-34 age group with a male to female ratio of 1.8:1 (Table 3.25). Among the three major ethnic groups, Chinese had the highest incidence. Foreigners comprised 27.7%
of the indigenous cases (Table 3.26).
Table 3.25
Age-gender distribution and age-specific incidence rates of indigenous zika cases^, 2016
Age group Male Female Total % Incidence rates per
100,000 population*
Total 264 191 455 100 8.1
^Cases acquired locally among Singaporeans, permanent and temporary residents.
*Rates are based on 2016 estimated mid-year population.
(Source: Singapore Department of Statistics)
ZIKA VIRUS INFECTION
Zika virus infection is transmitted by Aedes mosquitoes, similar to dengue. Only about one in five infections are symptomatic. The disease is usually self-‐limiting, although rarely, serious neurological complications have been reported. The disease is characterised by fever, rashes, joint pain, muscle pain, headache and conjunctivitis. Most symptoms last for four to seven days. The main vector in Singapore is the Aedes aegypti mosquito.
A total of 458 laboratory-‐confirmed cases of zika virus infection were reported in 2016 (Figure 3.16). In May 2016, Singapore identified its first imported case of zika virus infection in a traveler returning from Brazil. No further cases were identified for three months. On 22 August 2016, a primary healthcare doctor notified the Ministry of Health of an increase in cases with fever, rash and joint pain in the Kallang-‐Aljunied neighbourhood. Investigations confirmed the first cluster of zika virus infection.
Out of the 458 cases, three were imported cases, involving two Singapore residents and one foreigner with work permit. The remaining 455 cases were indigenous cases.
Figure 3.16
Weekly distribution of reported zika cases, 2016
The incidence rate among indigenous cases was highest in the 25-‐34 age group with a male to female ratio of 1.8:1 (Table 3.25). Among the three major ethnic groups, Chinese had the highest incidence. Foreigners comprised 27.7%
of the indigenous cases (Table 3.26).
Table 3.25
Age-‐gender distribution and age-‐specific incidence rates of indigenous zika cases^, 2016
^Cases acquired locally among Singaporeans, permanent and temporary residents.
*Rates are based on 2016 estimated mid-‐year population.
(Source: Singapore Department of Statistics) 0
ZIKA VIRUS INFECTION
Zika virus infection is transmitted by Aedes mosquitoes, similar to dengue. Only about one in five infections are symptomatic. The disease is usually self-‐limiting, although rarely, serious neurological complications have been reported. The disease is characterised by fever, rashes, joint pain, muscle pain, headache and conjunctivitis. Most symptoms last for four to seven days. The main vector in Singapore is the Aedes aegypti mosquito.
A total of 458 laboratory-‐confirmed cases of zika virus infection were reported in 2016 (Figure 3.16). In May 2016, Singapore identified its first imported case of zika virus infection in a traveler returning from Brazil. No further cases were identified for three months. On 22 August 2016, a primary healthcare doctor notified the Ministry of Health of an increase in cases with fever, rash and joint pain in the Kallang-‐Aljunied neighbourhood. Investigations confirmed the first cluster of zika virus infection.
Out of the 458 cases, three were imported cases, involving two Singapore residents and one foreigner with work permit. The remaining 455 cases were indigenous cases.
Figure 3.16
Weekly distribution of reported zika cases, 2016
The incidence rate among indigenous cases was highest in the 25-‐34 age group with a male to female ratio of 1.8:1 (Table 3.25). Among the three major ethnic groups, Chinese had the highest incidence. Foreigners comprised 27.7%
of the indigenous cases (Table 3.26).
Table 3.25
Age-‐gender distribution and age-‐specific incidence rates of indigenous zika cases^, 2016
^Cases acquired locally among Singaporeans, permanent and temporary residents.
*Rates are based on 2016 estimated mid-‐year population.
(Source: Singapore Department of Statistics) 0
Ethnic-gender distribution and ethnic-specific incidence rates of indigenous zika cases^, 2016
Male Female Total % Incidence rates per
100,000 population*
Foreigners 95 31 126 27.7 7.5
Total 264 191 455 100 8.1
^Cases acquired locally among Singaporeans, permanent and temporary residents.
*Rates are based on 2016 estimated mid-year population.
(Source: Singapore Department of Statistics)
There were a total of 15 clusters notified in 2016 (Table 3.27). The two largest clusters were at Aljunied Crescent / Sims Drive and Elite Terrace area. The largest cluster, located at Aljunied Crescent / Sims Drive had a total of 298 cases. The second largest cluster, with 13 cases, was at Elite Terrace / Fidelio Street / Jalan Tua Kong / Tua Kong Green / Siglap Rd area. The rest of the cases were sporadic cases that did not form a cluster.
Table 3.27
Zika virus infection outbreak clusters identified, 2016
S/No. Locality No. of
cases Transmission
4 Bedok Nth St 3 (Blk 542, 544, 545) 7 28/10/2016 24/11/2016 27
5 Bedok Nth Ave 2 (Blk 514) / Bedok Nth Ave 3
(Blk 404, 405, 507) / Bedok Nth St 3 (Blk 525) 5 22/8/2016 9/9/2016 18
6 Ubi Ave 1 5 1/10/2016 22/10/2016 21
7 Bishan St 12 (Blk 122, 123, 134) 4 1/9/2016 5/9/2016 4
8 Joo Seng Rd (Blk 17, 18, 21) / Vernon Pk 4 26/8/2016 10/9/2016 15
9 Ubi Ave 1, Cres 4 31/8/2016 11/9/2016 11
10 Jln Belangkas / Jln Chengkek / Jln Raya 4 8/10/2016 18/10/2016 10 11 Balam Rd (Blk 29) / Circuit Rd (Blk 35) / Jln
Raya 3 30/8/2016 10/9/2016 11
12 Jln Daud / Jln Ishak 3 21/10/2016 26/10/2016 5
13 Hougang Ave 7 (Blk 325) 2 31/8/2016 11/9/2016 11
14 Sengkang Ctrl (Blk 272C) / Sengkang East Ave
(Blk 279C) 2 3/9/2016 14/9/2016 11
15 Haig Rd (Blk 11) 2 3/11/2016 5/11/2016 2
Outbreak at Aljunied Cres (Blk 95, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112) / Aljunied Rd / Aljunied Rd (Blk 125) / Circuit Rd (Blk 61, 85) / Geylang East Ave 1 (Blk 126) / Geylang East Ctrl (Blk 122) / Lor 21A, 23, 25 Geylang / Paya Lebar Way (Blk 91, 120, 121, 122, 123) / Pipit Road (Blk 54, 56, 92A) / Construction Site @ Sims Dr / Sims Dr (Blk 42A, 43, 44) / Sims Pl (Blk 52, 53).
On 27 August 2016, the Ministry of Health (MOH) was notified of a locally transmitted Zika case residing at Block 102 Aljunied Crescent. As MOH was conducting a look-back exercise, within a day, 40 more cases were reported in the vicinity of the index case. Epidemiological investigations, vector control operations and outreach activities were carried out. A total of 298 cases were reported in the outbreak. All the cases had onset dates between 31 July 2016 and 25 September 2016. The epidemic curve of the cluster is shown in Figure 3.17.
Figure 3.17
Time distribution of 298 zika cases in the Aljunied Crescent outbreak area 279C)
15 Haig Rd (Blk 11) 2 3/11/2016 5/11/2016 2
Outbreak at Aljunied Cres (Blk 95, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112) / Aljunied Rd / Aljunied Rd (Blk 125) / Circuit Rd (Blk 61, 85) / Geylang East Ave 1 (Blk 126) / Geylang East Ctrl (Blk 122) / Lor 21A, 23, 25 Geylang / Paya Lebar Way (Blk 91, 120, 121, 122, 123) / Pipit Road (Blk 54, 56, 92A) / Construction Site @ Sims Dr / Sims Dr (Blk 42A, 43, 44) / Sims Pl (Blk 52, 53).
On 27 August 2016, the Ministry of Health (MOH) was notified of a locally transmitted Zika case residing at Block 102 Aljunied Crescent. As MOH was conducting a look-‐back exercise, within a day, 40 more cases were reported in the vicinity of the index case. Epidemiological investigations, vector control operations and outreach activities were carried out. A total of 298 cases were reported in the outbreak. All the cases had onset dates between 31 July 2016 and 25 September 2016. The epidemic curve of the cluster is shown in Figure 3.17.
Figure 3.17
Time distribution of 298 zika cases in the Aljunied Crescent outbreak area
Of the 298 cases, 208 (69.8%) were Singapore residents. Majority of the cases (89.6%) were in the 15-‐65 age group.
The male to female ratio was 1.4:1. Based on the reported occupations, the cases comprised six unemployed persons, seven drivers, nine retirees, 10 housewives, 29 students, 58 construction workers and 138 working adults.
Information was not available for the remaining 41 cases. Figure 3.18 shows the geographical distribution of cases in the cluster.
Geographical distribution of 298 zika cases in the Aljunied Crescent outbreak area
A total of 121 mosquito breeding habitats were detected and destroyed. 17.4% of the breeding habitats found in the cluster were domestic containers (containers and pails) and 12.4% were ornamental containers (flower vases, flower pots and flower pot plates). 52.1% of the breeding habitats were found in residential premises, 40.5% in outdoor areas and 7.4% in a construction site.
There were six profuse breeding detected, including a puddle on a roof top (300 larvae), a plastic pail (200 larvae), a ground depression (200 larvae), a container on a rooftop (200 larvae), an unused scupper pipe (100 larvae) and a closed drain (100 larvae).
Of the 298 cases, 208 (69.8%) were Singapore residents. Majority of the cases (89.6%) were in the 15-65 age group.
The male to female ratio was 1.4:1. Based on the reported occupations, the cases comprised six unemployed persons, seven drivers, nine retirees, 10 housewives, 29 students, 58 construction workers and 138 working adults. Information was not available for the remaining 41 cases. Figure 3.18 shows the geographical distribution of cases in the cluster.
Figure 3.18
Geographical distribution of 298 zika cases in the Aljunied Crescent outbreak area
56
A total of 121 mosquito breeding habitats were detected and destroyed. 17.4% of the breeding habitats found in the cluster were domestic containers (containers and pails) and 12.4% were ornamental containers (flower vases, flower pots and flower pot plates). 52.1% of the breeding habitats were found in residential premises, 40.5% in outdoor areas and 7.4% in a construction site.
There were six profuse breeding detected, including a puddle on a roof top (300 larvae), a plastic pail (200 larvae), a ground depression (200 larvae), a container on a rooftop (200 larvae), an unused scupper pipe (100 larvae) and a closed drain (100 larvae).
Contributed by
Charlene Tow, Chen Hongjun, Cherie See, Georgina Lim,
Peh Xinyi, Steven Ooi, Wong Jia Ying, Zul- Azri As-Saad