Zika virus

An Emerging Pathogen

Definition

Zika virus (ZIKV) is a

mild, short lasting febrile

Illness.

History

ZIKV was first discovered in April1947 when a

research rhesus monkey living in the Zika forest

Uganda developed an unknown febrile illness.

Conducted studies established that ZIKV was

endemic to Africa and Asia. It was first isolated

in humans in 1952 in Uganda and Tanzania.

Spread of ZIKV

In April - July 2007 the first outbreak of ZIKV

outside Africa and Asia was reported. This

occurred on the Yap island in the federated state

of Micronesia. It was then identified in French

Polynesia in 2013 and the most recent confirmed

outbreak outside Africa and Asia was in April

2015 in Brazil.

ZIKV Outbreaks

Since its first discovery in Uganda, ZIKV has

been detected in Nigeria, Egypt, Gabon,

Senegal, Sierra Leone, Tanzania, India, Pakistan,

New Caledonia, Easter Island, Indonesia,

Malaysia, Philippines, Thailand, Vietnam, Cook

Island, Yap Island, French Polynesia and Brazil.

ZIKV Outbreaks Cont’d

On 7 May 2015, the Pan American Health

Organization issued an alert recommending that

member states, vulnerable to the introduction of

ZIKV, establish and maintain appropriate

measures for surveillance, control and clinical

management of ZIKV infection.

Agent

ZIKV is a member of the flavivirus

genus and flaviviridae virus family. It is

closely related to Dengue, Yellow Fever,

West Nile and Japanese Encephalitis

Virus.

Photo of Flavi Virus

Vector

Aedes Africanus: ZIKA forest

Aedes Aegypti : Malaysia

Aedes Hensilii : Yap Island

ZIKV was later isolated in Aedes Vitattus,

Aedes Apicoargenteus, Aedes Furcifer and

Aedes Luteocephalus

Photo of Vector

Aedes Mosquito

Reservoir

During studies of yellow fever in the

Zika forest of Uganda, a rhesus monkey

who was tethered in a tree developed a

fever. Serologic studies later identified

the ZIKA Virus. To date the monkeys

still remain the only reservoir.

Rhesus Monkey

Mode of Transmission

Transmission is via the bite of the Aedes

Aegypti mosquitoes. However the Aedes

Hensilli was the predominant mosquito

species identified.

Human to Human Transmission

In 2009 professor Brian Foy a university

biologist contracted ZIKV in Senegal. On his

return to Colorado he became ill and later on his

wife also became ill with similar clinical

manifestations. Hence he proved that Zika Virus

could be sexually transmitted between humans.

Clinical Presentation

Fever (Between 37.8˚C-38.5˚C) Conjunctivitis Arthralgia Maculo-Papular Rash ( often starting on the

face and spreading) Myalgia Headaches (Retro-Ocular headaches) Diarrhoea

Diagnosis

Incubation period is usually between 3 -12 days

with illness lasting 2-7 days. The virus can be

detected during the first five (5) days after the

establishment of the clinical picture (acute

phase). RT-PCR (the reverse transcription-

polymerase chain reaction) test is done to detect

viral RNA.

Diagnosis Cont’d

Serologic Test (ELISA or Inmunofluerescence) :

to detect specific IgM or IgG against Zika Virus.

This could be positive after 5 – 6 days following

the onset of symptoms.

PRNT (Plaque Reduction Neutralization Test):

Confirmation of positive results.

Treatment

There is no vaccine or specific antiviral

treatment for ZIKA viral infection. Treatment

is symptomatic and supportive. This includes

rest, use paracetamol alone or with codeine for

pain and fever. Avoid Aspirins, Ibuprofen and

other anti-inflammatory drugs.

Treatment Cont’d

The use of antihistamines to control pruritis

is recommended in cases of maculopapular

rashes.

Drink plenty fluids to replenish lost from

sweating, vomiting and other insensible

loses.

Complication

Following the outbreak of the Zika virus a noted

increase in autoimmune and neurologic diseases

were observed. Researchers identified 73 cases

in a population of 270,000. Guillian-Barre

Syndrome accounted for 42 cases.

Prevention

Aedes Aegypti mosquitoes lay eggs in

man-made, water filled receptacles such

as water tanks, buckets, tyres, machinery,

pet water dishes and pot plant drip trays,

with mosquito eggs able to survive in

dried-out containers for up to 12 months.

Prevention Cont’d

Eliminate potential breeding sites Empty and spray insecticide to any old unused

container that has held water e.g. tyres, plastic containers, black sheet plastic, buckets or pot plant drip trays.

Store any containers upside down and undercover or under a domed tarpaulin in good repair. Punch holes in tins before discarding

Prevention Cont’d

Avoid using saucers or drip trays under pot plants. Let pots drain directly onto the ground or make sure saucers are emptied at least once/week. Wipe their inner surface firmly with a cloth several times or fill with sand, or spray with insecticide or apply methoprene insecticide pellets

Prevention Cont’d

Empty bird baths and pet drinking water at least weekly and spray with insecticide, or use methoprene pellets

Cover and completely seal septic tanks, rainwater tanks or other large water storage containers

Prevention Cont’d

Use methoprene briquettes in unsealed tanks as a temporary measure

Ensure roof gutters drain freely so that pools of water are not left at any low points. Throw a small amount of methoprene pellets on to the roof above problem gutters

Prevention Cont’d

NB:.

Fishponds with fish do not

breed mosquitoes. Tadpoles do not

eat mosquito larvae.

Prevention Cont’d

Personal Protection

To reduce the risk of mosquito bites in

ZIKV affected areas:Wear loose, light-coloured protective

clothing in outdoor situations, covering feet, legs and arms.

Prevention Cont’d

Use personal repellents containing DEET or picaridin on areas of exposed skin in combination with protective clothing

Use electric insecticide impregnated vapour pads in indoor or enclosed areas.

Prevention Cont’d

Avoid scents on the body, such as perfume, deodorants and sweat, since these can attract mosquitoes

Use electric insecticide impregnated vapour pads in indoor or enclosed areas

Prevention Cont’d

Avoid being outdoors between dusk and dawn to avoid mosquito bites, particularly in poorly lit areas, rural areas, or the outskirts of large towns

If accommodation is not well screened, sleep inside mosquito netting.

Use insecticide impregnated bed nets and clothing in high risk areas.

Public Health Implication

Zika virus is considered an emerging infectious

disease with the potential to spread to new areas

where the Aedes mosquito vector is present. The

discovery of ZIKV in Brazil is testimony to, the

potential for travel or commerce, to spread the

virus across large distances.

Public Health Implication Cont’d

The Caribbean, with our tropical climate, has

long been susceptible to mosquito- borne

diseases such as Yellow fever, Malaria, Dengue

fever and, most recently, Chikungunya. Now we

must be alert for the approaching Zica Virus

Public Health Implications

Bearing in mind that Aedes, a known agent of

the ZIKV is endemic to the Caribbean, the

approaching rainy season, the Carnival festival

which attract tourist, Commercial Activities, the

laboratory capacity to confirm suspected Zika

cases should be taken into account.

Public Health Implication Cont’d

Most importantly the potential neurological and

auto-immune complications that might require

specialised healthcare capabilities and treatment

chiefly ICU care, given our limited bed

Capacity, require keen consideration facing a

large-scale Zika outbreak.

Conclusion

To guarantee prevention success, it is

imperative to involve inter-sectoral

participation and collaboration at all levels of

government including: health, education,

environment, social development and

tourism sectors, among others.

Conclusion Cont’d

We also rely on support of non-governmental

organizations (NGOs). Communication channels

must remain open and community participation

should be mobilized. It is important to provide

clear, good quality information to the public

about this disease via communication campaigns.

Conclusion Cont’d

Vigilance must be enhanced towards imported

cases of ZIKV infection in St. Vincent and the

Grenadines especially with Carnival closely

approaching. Early detection of cases is

essential to reduce the risk of transmission.