A five‐year study of tetanus in the Cayo Santiago rhesus monkey colony: Behavioral description and epizootiology

Abstract

Tetanus is a major cause of death in the free-ranging rhesus monkey colony on the island of Cay0 Santiago, Puerto Rico. During the five-year period of observation (July 1,1976 through June 30,1981, the mean annual tetanus mortality rate (+ 1 SD) was 1.74% ( + 0.15). The mean annual total mortality rate was 6.77% (&0.78). The tetanus mortality rate varied significantly (P < 0.005) among the six troops on the island. Clinically confirmed tetanus accounted for 24.68% of the 231 deaths which occurred on the island during the study. Although the base population increased from 479 to 914 monkeys or 90.8% in five years, there were no significant changes in either the total or the tetanus mortality rates. The mean age of tetanus deaths was 6.9 years ( f 3.9) in the males and 7.1 years ( * 5.4) in females. The mean age-specific tetanus mortality rate increased with age. Of the 67 confirmed tetanus cases, 57 proved fatal (26 males, 31 females) for a case fatality rate of 85.1 %. There was no significant sex difference in the tetanus mortality rate. No confirmed cases of neonatal tetanus were observed. Infection of juveniles and adults of both sexes occurred chiefly through septic wounds, but postpartum infection of females was also noted. The peak incidence of tetanus deaths for both sexes occurred during the mating season of the annual reproductive cycle, as a consequence of increased levels of aggression and subsequent wounding. The diagnosis of tetanus was based solely on the clinical signs and was characterized by early behavioral abnormalities consisting of torpor, reluctance to interact with other animals, inability to prehend food, inordinate thirst, difficulty in swallowing, progressive stiffening and adduction of the pectoral limbs, bipedal running, "kangaroo hopping," "toppling over," and pilo-erection. As the disease advanced, severely affected individuals developed the classic human triad of tetanus symptomato1ogy:trismus (lockjaw), extensor rigidity, and opisthotonus, which progressed in most cases to status epilepticus and death from respiratory paralysis or physical exhaustion. The course of the disease in fatal cases ranged in duration from 24 hours to ten days. Obese monkeys with mild cases of tetanus were the most likely to recover with some taking as long as a month to return to normal condition and regain body weight. Of ten recoveries, six were female and four male. Multiple cases were observed in one adult male, indicating that previous infections do not necessarily confer immunity to future attacks. Survivors did not have demonstrable antitoxin titers to Clostridium tetani toxin, thus con-

Climate and seasonal reproduction in the Cayo Santiago macaques

“…Significant correlations were found between monthly changes in the mean daily average temperature and the monthly distribution of both conceptions and births (percentage of total by month). Cay0 Santiago (1975)* 1975197619771978197919801981 Jan 1-15 were significantly correlated with the warmer months of the year (r, = .59, z = 1.97, p < .05), and births were negatively correlated with higher temperatures (rs = Relative humidity data were not available from the weather station on Cay0 Santiago. NOAA records for Humacao (August 1974-July 1975) were used to test for variation in humidity over an annual reproductive cycle.…”

A 75‐year pictorial history of the Cayo Santiago rhesus monkey colony

“…Both he and Kessler became increasingly concerned about the impact of tetanus on the animals as individuals and on the population as a whole. Their mutual interest in studying tetanus resulted in their first article on the CS macaques [Rawlins & Kessler, 1982], and the realization that behavioral biologists and clinical veterinarians could work cooperatively with the colony under the management policy in effect at the time. This understanding led to a new period at CS during which the colony was effectively used for noninvasive biomedical research during the annual winter round without disrupting ongoing behavioral studies [Rawlins & Kessler, 1986].…”

“…At the time, tetanus was a common cause of mortality in the colony [Rawlins & Kessler, 1982] and vaccination represented a major change in the veterinary care program for the colony. Since 1985, all monkeys have been vaccinated and tetanus infections have been eliminated [Kessler et al, 1988, 2006].…”

Morphological variation inHomo erectusand the origins of developmental plasticity

“…The founding individuals of the Cayo Santiago colony were M. mulatta collected in Northern India in the 1930s whose descendants continue as a free-ranging but provisioned population on Cayo Santiago Island, Puerto Rico [95]. During the early years of the colony the animals were undernourished, but the cohort included here are animals who died in the 1970s and 1980s who had been reliably provisioned with a high protein (24-26%) monkey chow diet in addition to freely foraging on tropical plants for many generations and thus can be considered to have experienced high nutritional sufficiency [96]. At the same time, the parasite load in the Cayo animals, while apparently asymptomatic, is reported to be as high as laboratory animals who would be symptomatic and treated for parasites [97,97].…”