Epidemiology and the prevention of malaria and West Nile virus infection in Greece, during 2010 and 2011

Introduction

Vector-borne diseases are already on the agenda asmajor public health issues in our country. During the last 2years in particular, an outbreak of West Nile virus (WNV) infection has occurred and anothervector-borne disease, malaria, has emerged as a public health threat. The April 2011 issue of the HCDCP e-bulletin was devotedto the WNV infection, so in thisissue we will focus on malaria and present the surveillance data on the WNV infection for 2011.

WNV infection

Surveillance data for 2011

A totalof 101 laboratory-confirmed cases of WNV infection wasidentified during 2011,76 of which showed symptoms of the central nervous system (CNS) (encephalitis or/and meningitis or/and acute flaccid paralysis) while25 cases showed milder symptoms (fever). Ninedeaths were reported, all of which were of patients who were more than65 years old with underlying disease. Oneof the 76 cases with CNS symptoms wasconsidered to have beenimported, becausethe patient had been stayingin Albania during the incubation period of the disease. Another one of these 76 cases concerned a French citizen, whose diagnosis was madein France, but the patient had stayed in Greece throughout the incubation period. The last of the 101 reported caseshad an onset date of18 October 2011. Since then, no other case has been reported. InFigure 1 we present the WNV infection cases by week of disease onset. The first reported case refers to week 28/2011 (11–17 July2011). The age of the patients ranged between 2 and 89 years (with a median age of 70 years).

InTable 1, the number and annual incidence of patients who werelaboratory-diagnosed with WNV infection with CNS manifestations per regional area of residence are presented for Greece in 2011. It should be noted that the residential area is a rough criterion for assessing the area of virus circulation.

 

Table 1: Number and annual incidence of patients with a laboratory diagnosis of WNV infection with CNS manifestations per area of residence, Greece, 2011

Regional area of residence Number of patients Patients per 100,000 population*
Karditsa 8 6.89
Larissa 12 4.20
Viotia 5 3.99
Trikala 5 3.83
Eastern Attica 15 3.71
Pella 5 3.45
Serres 5 2.65
Imathia 3 2.08
Chalkidiki 2 2.00
Western Attica 2 1.32
Kozani 1 0.65
Thessaloniki 6 0.53
Evoia 1 0.48
Etoloakarnania 1 0.45
Western sector of Attica 1 0.21
South sector of Attica 1 0.19
North sector of Attica 1 0.18
Central sector of Attica 1 0.09
Total 75 0.67

 

*Calculation based on the population data provided by the National Statistical Service
(2008 forecast)

Malaria

Epidemiological data for 2011

Malaria is endemic in more than 100 countries around the world, mainly in subSaharan Africa and Asia. In Greece, the disease was eradicated in 1974, after an intensive malaria eradication program (1946–1960). Since then approximately 30–50 cases are reported annually, the majority of which are related with travel to or staying in a country with endemic malaria. Sporadic malaria cases without a reported travel history were recorded in 1991, 1999, 2000, 2009 and 2010.

In 2011, 40 laboratory-confirmed cases of malaria were reported with no history of travel to malaria-endemic countries. Thirty-fourof these cases resided in the municipality of Evrotas, Laconia, two in Evia, two in eastern Attica, one  in Larissa and one in Viotia. All of the cases were confirmed to have Plasmodium vivax infection by the Department of Parasitology and Tropical Diseases of the National School of Public Health.

In the area of Laconia, 23 malaria cases occurred in migrants from malaria-endemic countries, althoughtheir travel history and date of arrival in Greeceare not clear.

Figure 2 shows the cases of malaria in the affectedareas ofGreece (the municipality of Evrotas Laconia and other areas with evidence of local transmission) per week of symptoms. The last incident was a Greek patient whose symptoms began on 18 October 2011. The ages of the Greek cases without travel history to an endemic country ranged from 19 months to79 years old (with a median ageof 47 years);57.6% were men.

Malaria should be included in the differential diagnosis of patients with fever not attributable to anyapparent cause, especially if the patient has traveled to or come from a malaria-endemic area. A prompt and accurate parasitological diagnosisby the nearest microbiological laboratory capable of conducting a laboratory examination is essential in all suspected cases of malaria.

A ‘suspected’case of malaria is any incident with a clinical picture compatible with malaria, especially if the patient has a travel history concerning or resides in an area where local transmission of malaria has occurred.

For all laboratory-confirmed malaria cases, as well as all suspected cases where there is no possibility of laboratory confirmation at a local level,a sample of blood (complete blood vial) and/or the coating (tile) on which diagnosis was based should be sent for microscopy examination and polymerase chain reaction (PCR)at one of the following laboratories.

Department of Parasitology, Entomology and Tropical Diseases
National School of Public Health
196 Alexandra Avenue
115 27 Athens
Tel: 213 2010317, 213 2010318
Contact: Professor Nikolaos Vakalis
Microbiology Laboratory
School of Medicine, University of Athens
75 Mikras Asias
115 27, Athens
Tel:210 7462011, 210 7462133, 210 7462140
Contact: Professor Athanasios Chakris

Malaria is one of the mandatory notifiable diseases in our country. Each malaria case that has been laboratory-confirmed should be reported immediately to the Hellenic Center for Disease Control and Prevention (HCDCP). The relevant notification form for malaria can be found on HCDCP’swebsite. The form should besent by fax to the Department of Epidemiological Surveillance and Intervention of HCDCP

(tel: 210 8899000, fax: 210 8818868, 210 8842011).

 

Treatment

An early diagnosis and appropriate treatment is necessary to interrupt the chain of transmission of malaria. The recommended treatment is determined by the Plasmodium species, the disease severity, the risk factors of the patient (e.g. pregnancy), the possible resistance of Plasmodium to antimalarial drugs, and the patient’s country of origin or travel.

If someone is infected with P. vivax, itis not considered necessary for that person to be hospitalized, under the condition that his or her clinical symptomsaremild according to the assessment of the clinician. The recommended schedule for radical treatment of uncomplicated malarialP.vivax includes administration of chloroquine and primaquine. Administration of primaquine is needed to treat hypnozoites in the liver and prevent relapses. Guidelines for the treatment of malaria in Greece can be found onthe HCDCP’s website (www.keelpno.gr).

 

Actions by HCDCP for malaria

The Ministry of Health and HCDCP are in constant communication and co-operation with European and international public health centers and the World Health Organization (WHO) to assess the risk for our country and Europe generally. Moreover, HCDCP and the Ministry of Health, in co-operation with all stakeholders, have already developed a strategic action plan for the control of malaria in Greece, which defines the actions to be carried outduring the next period of increased movement of Anopheles(spring–autumn 2012).

According to WHO recommendations, as listed in the joint WHO-European Center for Disease Control and Prevention (ECDC) assessment mission in response to the 2011 malaria outbreak in Lakonia, Greece, 10–14 October 2011 (WHO travel report), and according to the  working groups of the inaugural meeting of the Special Program for the Control of  West Nile Virus and Malaria, Strengthening Surveillance inthe Greek Territory, which takes place under the operational program Human Resources of the NSRF (2007-2013), the following actions are carried out.

Detection and treatment of malaria cases (case detection and management). In any suspected case of malaria, a laboratory examination is made. Confirmed cases receive the appropriate treatment either during their hospitalization or directly supervised (directly observed therapy) by HCDCP units.

Reinforcing the capability of a rapid and early laboratory malaria diagnosis at a local level. A seminar was organized for laboratory personnel throughout the country by the National Malaria Reference Laboratory (National School of Public Health),andrapid diagnostic tests will be distributed at primary  health care centers in order to enable an authoritative and timely control of any suspected case of malaria (within 24 hours of examination) and the immediate initiation of treatment.

Investigation of the particular case andrisk factors (case investigation). Each confirmed case of malaria with evidence of local transmission is to be investigatedpromptly with a face-to-face interview using a structured questionnaire, in order to investigate the risk factors, identify the possible site of transmission and assess the risk of further transmission.

Investigation of the case’s domicile (focus investigation) andan active search for other cases in the environment of the known case. Foreach confirmed case of malaria with evidence of local transmission, an outbreak investigation is carried out as quickly as possible, with anactive search for other cases in the environment of the known case, coveringan area of about 100 meters radius around the case’s  domicile.

Active laboratory surveillance. The goal is to identify and report newly diagnosed cases. An active laboratory surveillance was performed inLakonia on a daily basis during the summer and autumn of 2011, in co-operation with the microbiology laboratory of the Hospital of Sparta.

Active searching for cases of malaria in the general population. Anactive search for cases hasbeenin place since October 2011 in the municipality of Evrotas in Lakonia. Periodic visits are made (every 15 days) toall residences/accommodation of the inhabitants incertain areas, permanent and occasional (such as migrants who work in seasonal agricultural works), in order to identify suspected cases with fever (temperature measurement, fever screening) or a febrile history,and carry out laboratory tests. Because ofthe alertness and awareness of the indigenous population tothe clinical aspects of malaria and the importance of early diagnosis, the active case search is only continuingin high-risk groups such as migrants and Roma, becauseaccess and referral to health services of suspected cases belonging to non-minority population groups is assured.

 

Screening migrants from malaria-endemic countries. A mass screening for malaria control wasstarted formigrants from endemic countries inthe municipality of Evrotas, Lakonia, in April 2012. The aim is laboratory testing for malaria with RDTs of all migrants from endemic countries. The screening is carried outonce for asymptomatic migrants as well as of all suspected cases of malaria, i.e. symptomatic individualswith a compatible clinical picture or history of fever during the last 15 days.

Screening is also carried out of people who are considered to be at high-risk because of exposure to mosquitoes or reduced access to health services, such as Roma.

Informing the public about malaria and protection measures. An informationleaflet has beenproduced,describing protection against mosquitoes,thatis available fromthe HCDCP website (www.keelpno.gr) and has been distributed to municipalities, hospitals and healthcare centers, tolls (Elefsina and Afidnes), post office branches and churches. More than 1.5 million brochures and 50,000 posters have been distributed. In 2011, home visits were made to all villages inthe municipality of Evrotas where cases of malaria were reported, in order to inform the local residents about the symptoms and precautions that can be taken against malaria.  In 2012, information workshops have been organized inall villages and forspecial population groups (e.g. Roma) in the municipality of Evrotas, and are still ongoing.

Informationsessions have been carried outforstudents, teachers, parents and clubs inthe area.

Increasing awareness and training forhealth professionals. HCDCP, onceacase has been reported without a travel historyto an endemic country, as a first priority notifies the Ministry of Health and the Department of Public Health of the relevant region. HCDCP also alertsclinicians in the region (public hospital,health centers and private doctors) tothe need for prompt diagnosis and appropriate malaria treatment. In addition, the Co-ordinating Center for Hemovigilance takes all the necessary measures for blood safety. In the area of the municipality of Evrotas, Lakonia, the awareness of healthcare professionals inall public health services has been increased through information days at the General Hospital of Sparti, the General Hospital–Health Center of Molaoi and at the health centers of Githio, Areopolis, Vlachioti, Kastoriou and Neapoli.

Health professionals and private doctors who could not attend the workshops, especially physicians, pediatricians, general practitioners, microbiologists, hematology and pulmologists, have been informed individually.

During the summer of 2012, another information workshop will be organized at the municipality of Evrotas and its neighboring regions, in order to remind people and increase awareness of the need for prompt malaria diagnosis.

Educational seminars. Alongside all the above-mentioned activities, training seminars are being conducted forrelevant bodies on the procedures forchecking mosquito control programs and action evaluation.

HCDCP is collaboratingwith the University of Thessaly onthe Special Program for the Control of West Nile Virus and Malaria, Strengthening the Surveillance in the Greek territory, which is takingplace under the operational program Human Resource Development of the NSRF (2007-2013). Different arms of the program include the development of geographical information systems (GIS), the strengthening of epidemiological surveillance for both diseases, the mapping of mosquito habitats and mosquito sampling from high-risk areas, the strengthening of bird and horse monitoring for WNV transmission, informative campaigns addressingthe public, especially high-risk groups, and health professionals who are involved directly withthe control and treatment of  both diseases, as well as the screening of immigrants at the borders, mainly those from endemic countries.

 

Discussion

WNV Infection

In 2011, fewer cases of WNV infection were reported in Greece compared with 2010, but there was a spread to the south and within the urban area of Attica. Thisphenomenon is similar to that observed in California in 2003. The resurgence and spread of WNV proves the existence of the virus in Greece and its circulation is expected to continue in coming years.

Malaria

WHOhas declared Greece malaria-freesince1974. However, the potential re-establishmentof the disease is a real threat because ofthe following factors.(a) The country is a place of residence and work for immigrants from endemic countries. (b) In many areas there are mosquitoes of the genus Anopheles, a malaria vector. (c) A change in environmental conditions has been noted, with a consequent increase in mosquito populations and activity. The reoccurrence and possible relocation of malaria in Greece is a major national problem with serious economic repercussions. This underlines the necessity of developing a wider strategy to combatthe disease, which includes intensification of the mosquito control program and increasing public and doctorawareness ofprompt malaria diagnosis and case treatment. HCDCP has prepared an action plan for managingmalaria for 2012–2015, which is presented in this issue.

The most appropriate measures for managingmalaria and WNV infectionsareenhanced epidemiological surveillance, systematic mosquito control measures as well as personal protection measures againstmosquitoes, medical practitioner awareness, laboratory preparedness, measures forblood safety and public awareness of the protection measures against mosquitoes.

 

M. Detsis, E. Papanikolaou, D. Pervanidou, M. Tseroni, E. Terzaki, G. Dougas, Department of Epidemiological Surveillance and Intervention


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