Dear Alok,

 This response will help you to define best what, why and how to approach your work and expectations

Dengue endemicity can be defined as the quality and/or intensity of  dengue been endemic ( incidence, prevalence nature and extend, geographical coverage to control programs) and can be categorized onto hyper-, meso, hyo, holoendemicity in a particular settings. Thus,

 This can help to appreciate the diversity of dengue

 This can also to understand the risk factors affected the patterns of vector and human interface

 This can be can useful in assessing the local or imported transmision dynamics

This can further help you to intepret the local trends and burden including cost effectivenens and performance of existing  rograms and interventions

Thanks

Dr Tambo

Disease Surveillance Specialist & Pharmacologist

In addition to Dr Tambo, I would also say u need to quantify the disease by some sample or large scale active screening of antibodies ( IgG , IgM) and current NS1, this will give you sero  conversion due to dengue and percent of new infections per year if you do it for two three years. Also the strains identification of circulating dengue of virus.

Thanks,

It depends on the focus question

It can be evaluated in terms of :

(1) Diagnostics in idntification and characterization of Aedes or virus profiling either biochemical (NS4 or other can be used) or Serological ( IgM/IgG+_ NS4) or Molecular genoptyping using the right primers(DENV11-4)

(2) Vector control programs, here EIR=entomological incubation rate can be very useful in addition to the patterns of IRS sprays or fumigation

(3) epidemiological control or treatment- here prevalence of cases of dengue in populations either human or animals can be useful information.

He needs to be specific in the  research question and focus on doable based on its budget.

Best 

Dengue Surveillance

To quantify endemicity or epidemic dengue requires an active laboratory-based disease surveillance programme (using serological and virological diagnosis) that can provide early warning of impending epidemic transmission. However, for early detection of suspected cases, routine monitoring of fever cases in sentinel sites should be considered.

I believe the public health surveillance system in Barbados should provide you the background  data for suspected and confirmed dengue infections in particular year or period. These monitoring of dengue incidence and prevalence over time establishes a baseline measurement of the background rate of disease so that an unexpected rise in the number of cases or the proportion of severe cases will trigger an alert and further investigation.

You should liaise with the relevant department in the Ministry of Health and request for any Epidemiological bulletin and reports for the period you are interested. It is also important to note what kind of early warning methods have been utilized by the dengue prevention/control program in the country to address outbreaks or unusual occurrences. You may learn If they have Case based surveillance, and event based surveillance, Passive or active surveillance etc. It is important to note what are  the surveillance definition of "dengue" and "severe dengue" or in the past DHF..

Dengue Threshold (WHO 2009):

The threshold for alert and response will vary according to the operational level affected (local, national, international) and whether the affected area is endemic for dengue or at risk of its introduction. For example, at the local level a single dengue case may trigger action. At state or provincial level, the increase in reported cases above an established baseline for the same week or month in preceding years, or increasing vector density, may indicate impending epidemic activity. At national level, the detection of changes in virus serotype, subtype or genotype distribution, clinical severity or seropositivity rate, or the introduction of a dengue vector into a new ecological niche and severe dengue. 

Indicators  to determine epidemic detection (threshold)

1. Excess cases of dengue

2.Virus isolation rate in excess of routine virological testing rate measured as the

increased proportion of blood samples positive for dengue viruses in the low

season for dengue.

3.Fever alert – i.e. an unexpected and unusual increase in the number of fever

cases – may be a useful signal of increased dengue activity in locations where the

frequency and differential diagnosis of acute febrile illness is limited

4) The appearance of a new dengue serotype can be used as an early warning signal but does not predict the occurrence of an immediate epidemic

Gubler DJ. Dengue and dengue hemorrhagic fever. Clinical Microbiology Reviews,

1998, 11(3):480–496.

WHO 2009, Dengue: guidelines for diagnosis, treatment, prevention and control -- New edition.

http://www.who.int/tdr/publications/documents/dengue-diagnosis.pdf

Earnest, Himmat and Yitades. Thanks for providing above leads.

I should have given some more back ground to my question and should have framed the question more clearly.

ok so where do i begin?

Barbados is endemic for dengue and all four types have been isolated, some times more than one type simultaneously. 

It has an ACTIVE surveillance for dengue.

There is an ongoing vector control program since early eighties.

Remember it is a top tourist destination in the Caribbean.

I have in more than one ways looked at the epidemiology of dengue and its trend in this country including serosurveillance of the entire population with several publications as you already know.

Now i am sitting on a database of all the suspected and confirmed cases of dengue in this country for the year 1996 to 2013 collected prospectively.

My question is - Is the dengue burden in this country getting bigger or is stable or getting smaller and what is its interaction with the season and climatic change (rain fall pattern).

So what I need advice on is what are the parameters that i can look at to answer the above question? Can one or more of these parameter such as degree of endemicity quantifies and if there is any standard for it?

Of course the big idea is to answer the question- is should this country be worried and do something more than what is being done to control dengue?

I have read a whole lots of published literature on dengue including the WHO publication mentioned but this topic is never dealt with clarity or objectivity.

Dear Alok,

 Thanks, hoping these practical steps will be useful and valuable with the growing trend of Zika epidemics  and dengue endemicity in the region, there is an urgent need to act fast and timely on preventive measures,  preparedness and emergency at all levels( mainly at community level):

(1) to establish a real time and active surveillance such as Fever checks at entry points due to the number of tourists, while robust political commitment and advocacy is need to invest on proven best methods in reducing the Aedes breeding sites and other risk factors.

(2) Government and stakeholders MUST embark on intense community awareness, education, social mobilization and engagement of Zika or dengue potential transmission source and impacts due to unprotected causal sexual intercourse with tourists, blood products transfusion and  Aedes bites... as well as dengue

(2a) The urgency to  embark on Health workers at all level reeducation  and traning  including Laboratory testing (  serological and RT-PCR)  on potential signs and symptoms is needed  mainly to pregnancy women counselling, family planning due  to Zika linked microcephaly and neurological aberrations in pre, during and post natal pregnant women sessions in hospitals, community health care centers in rural and clinics should be re-enforced by laws, in addition to scaling up access and availability of free contraceptive usage to most vulnerable

(3) To revamp innovative  integrated vector control programs in various settings  to limit or reduce Aedes competence, virulence and potential vulnerability.

(4) To set up urgently a practical a regional or national preparedness and emergency response unit that practicing on various scenario, understand the vector or disease dynamics and complications and fashion best ways / solutions to respond timely and effectively.

(5) some funding for tourism activities should be directed to R&D in Aedes and related viral diseases as well as other infectious/ zoonotic diseases  vaccines and drugs discovery and mainly understanding local operational research gaps.

In addition the link PAHO provided by Yitades above will show you practical step that require contextual adaptations based on local realities , may be some technical expertise and support could be beneficial in setting a robust and sustainable surveillance- response systems.

Further analysis of retrospective review of your old data could provide you with  insights into endemicity of dengue in the country including seasonal variations and patterns of dengue and directly or indirectly on potential patterns of Zika with recent knowledge such as sexual transmission or transplacental transmission or blood products ttransfusion

Ernest thanks. much of those action points mentioned by you are already in action in this country. Thanks for highlighting them.