MALARIA EXPEDITION TO NIGERIA 55 
and perstans, and diurna and perstans respectively, while N.D.P. indicates the triple 
infection. The diagnosis of the nature of the infection is based on the examination 
of the blood at twelve mid-day and twelve midnight, and a case was judged to be 
one of F. nocturna or F. diurna, according to the presence of the larger number of 
filariae at one or the other time ; where the numbers were close the infection was 
noted as a mixed nocturna and diurna, although we are aware that this may not have 
represented the actual state of infection, as will be seen below in the paragraph on 
' periodicity.' 
TABLE I. 
No. 
No. infected with 
examined 
N. 
D. 
p. 
N.D. 
N.P. 
D.P. 
N.D.P. 
Natives of : — 
Southern Nigeria, including the Old 
Calabar and Cross River districts ; 
Bonnv, Opobo and New Calabar 
districts ; Akwete district ; Brass, 
Wari, Sapele and Benin River 
districts, and the Lower Niger 
district extending as far as Idah ... 
'35 
7 
I Q 
7 
16 
7 
/ 
2 
2 
I 
Northern Nigeria, including Lokoja and 
the regions of Sokoto, Kano, and 
the Benue River district ... 
22 
3 
2 
2 
I 
I 
Lagos and hinterland ... 
6 
2 
Gold and Ivory Coasts ... 
4 
1 
1 
1 
Kroo Coast 
4° 
3 
I 
1 
2 
1 
1 
Other districts, including Sierra Leone ; 
and a few natives whose native 
country was not ascertained 
18 
I 
3 
1 
Totals 
225 
2 5 
23 
1 O 
4 
3 
3 
The following table shows the percentage of infected natives in towns having 
different sanitary conditions ; for example Group I contains a number of towns 
and villages situated chiefly near the mangrove swamp, which are usually in a 
deplorable filthy condition ; the natives of this group were found to be infected with 
haematozoal embryos to the extent of 50 per cent. ; whilst Group II contains 
comparatively clean up-country towns in the region beyond the mangrove swamp. 
Group III are large coast towns. 
