An Outbreak of Trichinellosis in the District of Pasvalys, Lithuania

  Published: 06.03.06 Updated: 07.03.2006 09:33:46

A. Bartuliene, V. Jasulaitiene, B. Morkunas, G. Zagrebneviene,

National Centre for Communicable Diseases Control and Prevention, Lithuania

In January 2001, 124 persons sought medical advice for symptoms compatible with trichinellosis. The geographic clustering and the epidemic curve suggested a common source outbreak. A comprehensive epidemiological investigation was initiated. The outbreak was traced to wild boars hunted on December 23. Trichinoscopy had failed to reveal that the meat contained Trichinella larvae.

Trichinellosis is a rare disease in Lithuania. In January 2001, an outbreak of trichinellosis occurred in Pasvalys district of Lithuania.


From January 21 to January 30, 124 persons (118 from one administrative district and 6 from other areas) sought medical advice for symptoms compatible with trichinellosis. The epidemic curve shows that most persons sought medical advice on January 22 - 26 (figure). There were 26 children under 14 years of age among those who sought medical advice.

Most patients complained of fever (47 out of 124), myalgia (43 out of 124), face and periorbital oedema (39 out of 124), diarrhea, nausea and vomiting (28 out of 124). 45 patients were hospitalized, 22 were treated at home, and 57 persons who had eaten the same meat but did not contract trichinellosis received prophylactic treatment with mebendazole.

The final diagnosis of trichinellosis was given for 67 persons (12 of them were children under 14 years) and was based on pathognomonical symptoms of trichinellosis, changes in blood and epidemiological research data. Eosinophilia ranged from 6 to 60 (average 20), leucocytosis ranged from 9.1 g/l to 24.8 g/l (average 13.5 g/l).

Minor and medium forms of the disease were diagnosed for most patients (93) and only 7 of patients developed severe trichinellosis. All patients recovered, and they are now under observation by the Primary Health Care Centres in their area.

Epidemiological investigation

The investigation started within 24 hours of the first case of trichinellosis being registered. After interviewing the patients, it was established that all of them had eaten wild boar and products made from this meat. Wild boars were hunted on 23 December 2000 in district of Pasvalys.

It was ascertained that hunters of Lepsyne (Pasvalys district) hunter circle (in total 13 hunters) shot four wild boars on 23 December 2000. The bag was divided among all the hunters. Veterinarian A who participated at the hunting took specimens of the meat for trichinoscopy but did not find any Trichinella larvae.

Specialists from the Panevezys Public Health Centre, Pasvalys branch, compiled data about the number of wild boars killed and results of laboratory testing from State Food and Veterinary Service of Pasvalys district. In the 24 January 2001 report, veterinarian A indicated that 4 wild boars were killed on 23 December 2000, 6 on 6 January 2001 and 1 on 13 January 2001. All slaughterhouse scrap was investigated, but Trichinella larvae were not detected.

Information about the first cases of trichinellosis spread very quickly. Hunters from the Lepsyne hunter circle presented the remainder of the boar and byproducts (about 58 kg) hunted on 23 December 2000 to the State Food and Veterinary Service for laboratory investigation. Comprehensive laboratory investigation identified numerous Trichinella larvae. The investigation was repeated in this laboratory for four wild boar diaphragma specimens kept in the refrigerator by veterinarian A. Trichinella was found in two specimens. A plentiful invasion of Trichinella larvae was found in the same product specimens by the laboratory of the State Food and Veterinary Service of Panevezys district.

Measures taken

  1. The National Centre for Communicable Diseases Prevention and Control co-ordinated activities and provided methodological assistance in organising epidemiological measures during the outbreak.
  2. Following the Director of State Public Health Care Service at Ministry of Health Care order a commission of specialists was formed. This commission organised activities of the Public Health and Health Care Services of Pasvalys district during the outbreak.
  3. A meeting was organised to discuss the use of preventive measures. The commission, physicians from Panevezys Infectious Diseases Hospital, physicians from Pasvalys Primary Health Care Centre, vice-chief of Pasvalys district and the investigator of the investigation division of Pasvalys district Police unit participated in this meeting.
  4. Local Administration Council of Pasvalys District prepared and established an Intersectoral Program of Preventive Measures to prevent cases of trichinellosis in the district taking into account the observations and suggestions of the Commission.
  5. Treatment, medical and dispenserical observation of patients with Trichinellosis was organised.
  6. Residents of Pasvalys district and Lithuania were informed about the outbreak of Trichinellosis through the mass media.
  7. The material from the investigation was provided to the investigation division of Pasvalys district Police unit in order to establish whether anyone had committed violations of legal acts that resulted in the origin of the outbreak. Criminal case was brought according to the facts and the investigation is currently taking place.


  1. 1. All hunters of the Lepsyne hunter circle and the members of their families, relatives, friends and employees who ate meat or products of the wild boars hunted on 23 December 2000 fell ill with trichinellosis. The family of one hunter, the veterinarian, did not fall ill with trichinellosis as they ate meat only after processing by autoclave. The results of the trichinoscopy on the boar performed on the day of hunting were doubtful. After repeated investigation it was ascertained that this meat contained Trichinella larvae and was the source of this trichinellosis outbreak.
  2. An intersectoral program of surveillance and control of trichinellosis is currently being prepared. The aim of this program is to reduce the incidence of trichinellosis in Lithuania, and to stop future outbreaks of this infection.