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COMMUNICABLE DISEASE SURVEILLANCE IN CROATIA

•    Communicable disease case notification in February

S a l m o n e l l o s i s.  Incidence decreased further in February (140:236)  being similar to February last year (137). The only small cluster was seen in Rijeka (18).

D y s e n t e r i a   b a c i l l a r i s.   Only 3 sporadic cases were reported.

H e p a t i t i s   A (epidemic jaundice). There were 9 diseased registered in February which is slightly more than in January (5). Small cluster is present in Pozega (6; see Epidemic outbreaks). In February last year there were less cases (4)

M o r b i l l i  (measles). No cases in February, as well as in previous month and  February last year, owing to vaccination.

R u b e l l a. Two cases reported in February, one from Dubrovnik one form Zagreb Tresnjevka, both unvaccinated. There were no cases in January neither in February last year.

T r i c h i n e l l o s i s. In February 2 cases were reported from Omis after consuming wild boar meat originating from another county.

A I D S.  In February  7 cases were reported, occurring actually in the last  six months period.

M a l a r i a .  One imported case is reported from Metkovic.

I n f l u e n z a. Seasonal epidemic wave developed quickly in February,  showing an increase of incidence that only influenza could cause (53545 : 334). Two strains of  virus influenzae were detected in the circulation: A/H3N2/ predominantly and A/H1N1/ much less.

•      No reports in February from:

Kastela, Vis and Lastovo, only 3 out of 113 epidemiological districts.

•      Epidemic outbreaks

        Following outbreaks were reported in February:

Note: in all outbreaks mentioned here, epidemiological investigation and necessary measures were undertaken, preventing thus other potential cases.

Rijeka – salmonellosis (S. enteritidis) after a birthday celebration held in a social club on 6.11. 2006. There were 25 diseased out of 31 exposed persons. Vehicle epidemiologically and microbiologically: French salad and home made mayonnaise. Source: someone from the kitchen staff, as few of them suffered from enteric illness, were found salmonella positive and were not exposed to incriminated food.

Osijek – legionellosis among inhabitants of one street, starting on 9.11.2006 with one diseased person, after which ten more persons were discovered having  serological indications of Legionella exposure. Mode of acquiring not found. Water samples from city water supply system negative for legionella.

Pozega  - family outbreak of hepatitis A. Between 8.1. and 25.1. 2007 there were 6 cases out of 10 family members. Source: probably a person affected in another outbreak (described in the last number of ENEWS) as families are connected.

Rijeka – gastroenteritis in a home for elderly persons. Causative agent: noro, Norwalk virus. Between 8.1. and 18.1. 2007 there were 22 diseased out of 450 exposed. Mode of spread: mainly by aerosol (via droplets).

Novi Zagreb – viral gastroenteritis (noro (Norwalk) virus) in a home for elderly persons, predominantly in the stationary. Between 12.1. and 25.1. 2007 there were 75 cases registered out of 380 exposed.  Mode of spread: mainly by contact.

Topusko – gastroenterits in a thermal treatment center, with a total of 33 diseased (staff and patients) out of 532 exposed persons,  between 14.1. and 22.1. 2007. Causative agent not found, bacteriological and virological (rota, adeno v.)  examinations negative. Mode of spread: contact and probably through aerosol.

Novi Zagreb – family outbreak of salmonellosis (S. enteritidis) on 16. 1. 2007. There were 3 diseased out of 4 family members. Source and vehicle not found.

Pula – viral gastroenteritis (noro, Norwalk virus) in a hospital. Between 16.1. and 6.2. 2007. the total of 90 cases were recorded (patients and staff) among cca 700 exposed. The majority of cases occurred in the same ward (82). Mode of spread: contact

Cakovec – viral gastroenteritis (noro Norwalk virus) in a home for elderly people. Between 16.1. and 11.2. 2007 there were 48 diseased out of 121 exposed persons.  Mode of spread: contact

Opatija – head lice in an elementary school. Total of 8 infested out of 200 exposed children  was recorded on 21.1. 2007.

Novi Zagreb – viral gastroenteritis (noro Norwalk virus) in a rehabilitation centre. Between 27.1. and 1.2. 2007. there were 17 diseased out of 83 exposed persons. Mode of spread: contact and probably partly through aerosol.

Petrinja - influenza in a home for elderly persons. Between 11.2. and 22. 2. 2007 there were 16 diseased mainly in the stationary part, and 3 in staff members. There were 248 persons present in the institution out of whom 200 were vaccinated. Only 3 diseased had been previously vaccinated.

Pula – food poisoning in a Mexican restaurant on 11.2. 2007. Total of 9 cases registered. Causative agent: Clostridium perfringens. This agent was not found in meals sampled in the restaurant during epidemiological investigation.

Sibenik – histamine poisoning in a family, after their lunch in a restaurant.  All 5 members turned ill, but not any other guest (cca 150 exposed). Vehicle not found with certainty, as no fish meal was eaten, but grilled minced meat, pomes frittes mineral water and bear. The disease started some forty minutes after suspected meal. All ingredients and meals from the restaurant turned negative for histamine however.

NEWS AND COMMENTS

•      Norovirus gastroenteritis outbreaks in Croatia

During the year 2006 and the beginning of 2007 (end of February) in Croatia there were 17 outbreaks reported, caused by a noro-virus, known also as a Norwalk agens, (Calici-virus group), involving the total of 821 diseased persons. Outbreaks were distributed through the whole year but more in winter, especially this winter  (Graph).

Graph 1 Norovirus gastroenterits outbreaks by months

The period mentioned was the most affected since laboratory diagnostics of noro-viruses has been  introduced in the country (few years ago). It is interesting that such increased activity of noroviruses has also been detected at the same time in other parts of Europe, according to ECDC (European Center for diseases control, Stocholm) weekly newspaper the Eurosurveillance of 14.12.06. (www.eurosurveillance.org). The reasons for the increased intensity are not entirely clear. As noroviruses belong to enteric microorganisms which are excreted in the stool and enter an organism mainly through the mouth, it is supposed that the main mode of transmission in outbreaks should be alimentary i.e. by food (especially raw) or drink, for instance: insufficiently washed green vegetable, fruit like strawberries or raspberries, or by contaminated water and drinks. However in the majority of examples no food or drink responsible had been detected, but contact. There is a similar situation in Croatia too. In 17 outbreaks registered in the mentioned period (see table), only in 3 outbreaks food has been epidemiologically incriminated (detection of virus in food or drink is technically problematic) and drink in one case.  In all other outbreaks contact was identified epidemiologically as the main mode of spread. In a  significant proportion  (3 cases) contact was combined with aerogenic i.e. via droplet (aerosol produced at vomiting) way, while in one example aerogenic (via aerosol) mode seemed to be dominant. Attack rate (morbidity rate) in these outbreaks was found to be very high, between 15% and 50 %, only in three cases it was  less than 5 % (in some outbreaks the denominator was not  determined so cells were left empty).   

Table 1 Outbreaks of noro virus gastroenteritis in Croatia 2006/2007

* water from an uncontrolled forest well can not be ruled out

Although the disease is of short duration and usually self-limiting, still it is very disturbing because of abundant vomiting, general toxic symptoms and malaise. Additionally, owing to high contagiousness, and a very low infective dose necessary, outbreaks can be prolonged in spite of measures. In hospital environment such prolonged outbreaks significantly interfere with planned work, operations, diagnostic interventions etc. In this light our own experience from recent outbreaks suggest that measures should be applied promptly after first few epidemiologically linked cases emerge, and should be maximally thorough and systematic. Anyhow, all classical hygienic measures preventing direct and indirect contact, including  a strict control of kitchens and laundry facilities, proved to be effective even in prolonged examples and had prevented the spread within institution. As an additional measure, the staff helping persons sick with norovirus gastroenteritis in health care institutions should wear protective masks and glasses, to avoid possible exposure to infective aerosol through mucosa of eyes, nose or lips.

There were 6 cases of malaria registered in Croatia in 2006. All 6 were imported i.e. acquired in some of malarious areas of the world. Croatia is free of autochthonous malaria since 1954.  The number is similar to the last year one (7). The following table shows, like in previous years (see ENEWS 1/2006), countries or areas where cases most probably originate from, than a type of plasmodium as well as information about chemoprophylaxis.

The above data are excerpted from standard inquiry forms, accompanying each individual notification of malaria case. Beside that data, patients occupation is evidenced too. In previous years it was usual that the majority of diseased were sailors. But in 2006 none of patients were of this profession. All were technical experts of various profiles, working abroad in some of malaric countries.

COMMUNICABLE DISEASES IN CROATIA                    February 2007

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