Chimpanzees of the Budongo Forest : Ecology, Behaviour, and Conservation

Discussion with the staff at Budongo Forest Project

The staff of BFP were questioned about the epidemic. This indicated that the outbreak of coughing
started on 11 November with NK coughing on that day. It spread rapidly and by Nov 21, 23 individuals
had been observed coughing. The following chimpanzees were affected: NK, BH, AY, KW, KZ, TK,
CL, JB, MH, GS, MU, ZG, KY, GZ, BK, HT, MA, NB, NR, MS, KL, KA, SR.

Symptoms

Symptoms varied between a dry cough to a wet, moist productive cough. GS has a bilateral mucoid
nasal discharge; BK, NB and MS had a unilateral mucoid nasal discharge. Some chimpanzees had
paroxysms of coughing, consisting of prolonged coughing of up to 40 seconds duration. No dyspnoea
or tachypnoea (difficulty in breathing) was observed. No increase in lethargy, depression or anorexia
was observed. These observations were strengthened by discussions with field assistants and visiting
researchers. An unidentified adult female and infant on the 17th November were reluctant to get out of
the nest until later in the day, and were coughing.
The chimpanzees did not lose vigour and were alert and responsive, including the infants, which were
seen to be active and continued to suckle.
Frequency of coughing in infants was greater that in adults. During the observation period, infant
NR coughed 3 times an hour with prolonged bouts and the mother, NB, coughed 4 times an hour.
Infant KA coughed 3 times an hour, and the mother, KY, coughed 2 times an hour. Infant ZG coughed
4 times an hour, and his older sister, GZ, coughed 5 times an hour, however their mother, ZM did
not cough.
Proportion of individuals observed coughing during the epidemic, 11–24th November 1999:

Report of necropsy on Ruda and outbreak of respiratory disease 257

Date Observed coughing rates

(% of all individuals

observed on that day)

11th 33

16th 25

17th 60

18th 75

19th 36

20th 66

22nd 80

23rd 70

24th 53

From 11th November to 24th November, 23 animals out of 34 observed (67.6%) were seen to be
coughing regularly. 11 animals (32.4%) were never observed coughing.
Only one animal, NK, had a determined period of disease. He was observed to start coughing on the
11th November, and stopped coughing 9 days later. In this case the course of the disease lasted for
9 days. For the rest of the individuals it was difficult to determine when the coughing started and ended,
as they were not observed every day prior to the start of coughing. From 24th November the incidence
of coughing declined, after which the epidemic slowly disappeared with no loss of life.