From 22 patients with Legionnaires' disease, 86 sera were examined for specific serotype 1 IgM and IgG antibodies by the indirect immunofluorescence technique.

No antibody was detectable until 8 days or more from the onset of symptoms. When produced the amount was widely variable and remained detectable for periods from less than 34 days to more than 1 year.

Initially IgM antibody predominated, ten patients produced only IgM in the first 21 days, six produced only IgM in the first 28 days and three did not produce IgG at any time. One patient, and possibly a second, produced only IgG antibody.

Since IgM antibody was still present in one patient after a year it is important not to accept the presence of this as evidence of very recent infection.

It is advisable that any type of serological test for L. pneumophila infection should detect the production of both IgM and IgG antibodies.

Possible origins of an epidemic of bluetongue in Cyprus in August 1977 have been analysed. First outbreaks occurred simultaneously in the south-east of the Famagusta district and on the north coast of the Kyrenia district respectively. Although the epidemic was due to type 4, which had been responsible for the previous outbreak in 1969, no evidence of persistence of virus could be found. Imports of domestic animals in the past year were not implicated since the imported cattle were introduced only to the southern part and not to the northern part of the island. Easterly, north-easterly and northerly winds during the period 11–14 August could have brought infected midges at a height of 0.5–1.5 km from Syria and Turkey, and such a movement would fit well the dates of the first outbreaks (20–25 August). Temperatures at a height of 1.5 km were 20–25 °C and at 0.5 km 30–35 °C, and with wind speeds 10–20 km h−1 the distance from Turkey and Syria would have been covered in 5–20 h. It follows that, in addition to surface winds, winds at all levels warm enough for flight should be taken into account when the possibility of disease spread by windborne midges is being assessed.