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Brucella arbortus

STLV SIV, STLV SIV, STLV, SFV Papillomavirus SIV, STLV

SIV, STLV

STLV, Alphaherpesvirus STLV, Hepatitis B STLV, Herpes B SIV, STLV

SIV, STLV

SIV, STLV, SFV, Hepatitis B,

Papillomavirus, Ebola SIV, STLV, Mycoplasma, Brucella, Herpes, Papillomavirus,

Cytomegalovirus STLV, Hepatitis B STLV SIV STLV

Polygynandrous Polygynandrous Variable: Polyandrous,

Polygynous, Monogamous Polygynous or Polyandrous Polygynandrous Polygynandrous or

Polygynous Polygynandrous or

Polygynous Generally Polygynous Polygynous Monogamous Polygynandrous Polygynandrous or

Polygynous Polygynandrous Polygynandrous

Polygynandrous

Polygynandrous/Dispersed Polygynous or Polygynandrous Polygynandrous Polygynandrous/Polygynous

1 Numbers after genera indicate number of species in which one or more of the parasites listed has been documented. Data from the Global Mammal Parasite Database (Nunn and Altizer 2005).

2 Most studies have not tested experimentally for sexual transmission. Parasites were coded as having a sexual component to their transmission based on the known biology of the pathogen, data from captive studies, or information from closely related host species (as described in Pedersen et al. 2005). It is important to note that many primate viruses recorded as sexually transmitted could also spread by other routes, including close non-sexual contact and vertical transmission.

In addition to mating promiscuity, other behavioral and morphological traits probably influence STD risk in primates. Species with complex genitalia, especially the "spines" found on the penises of some species (Fig. 3.10), could damage the genitalia of mating partners, thus increasing risk of disease transmission. The duration of intromission during mating obviously influences the duration of genital contact, with a longer period of copulation increasing the probability of STD transfer. Remarkable variation in the duration of intromission exists in primates (Dixson 1998; Dixson and Anderson 2004). Chimpanzees exhibit extremely short copulations, lasting on an average only 7 s and involving only 8.8 pelvic thrusts (Tutin and McGinnis 1981). By comparison, orangutans have been reported to copulate for over 45 min (Nadler 1977), and lesser galagos (Galago moholi) were observed to mount for up to 53 min (Pullen et al. 2000). STD risk might also be greater in primate species that have multiple

Fig. 3.10 Examples of penile spines found in primates. Images show scanning electron micrographs from (a) Callithrix jacchus, (b) Galagoids demidoff, (c) Galago (Otolemur) gar-netti, and (d) Microcebus murinus. See Dixson (1998) for further details on morphological classifications of these spines in primates. Images provided by A. Dixson, Conservation and Research for Endangered Species at the Zoological Society of San Diego.

Fig. 3.10 Examples of penile spines found in primates. Images show scanning electron micrographs from (a) Callithrix jacchus, (b) Galagoids demidoff, (c) Galago (Otolemur) gar-netti, and (d) Microcebus murinus. See Dixson (1998) for further details on morphological classifications of these spines in primates. Images provided by A. Dixson, Conservation and Research for Endangered Species at the Zoological Society of San Diego.

intromissions prior to ejaculation (Dewsbury and Pierce 1989; Dixson 1998), because this could increase the risk of micro-injury (abrasions, cuts) to the genitals and the total contact time for each copulation. Finally aggressive interactions among males that are competing for access to females could lead to the spread of disease (Tutin 2000).

3.3.4.3 Sex differences in disease risk

Three main factors can cause patterns of infection to differ between males and females (Zuk and McKean 1996; Combes 2001). First, body size dimorphism should require that males consume more resources, thus exposing them to more infectious stages of parasites. Their larger nutritional requirements could also make males more susceptible to infections (Barrett and Henzi 1998). Second, males and females are likely to differ in their exposure to directly transmitted parasites due to sex differences in social relationships, variation in access to mates, and differences in diet or habitat (Meade 1984; Nunn and Altizer 2004). Finally, sex differences in hormones could account for differences in parasitism, including effects of pregnancy on immune defenses (Solomon 1969; Alexander and Stimson 1988), or through the immunosuppressive effects of testosterone in males (Folstad and Karter 1992; Zuk and McKean 1996).

Studies covering a wide range of host species have demonstrated a sex difference in parasitism, with most studies finding higher prevalence or intensity of infection among males (Zuk and McKean 1996; Combes 2001). A recent comparative study by Moore and Wilson (2002) showed that across mammals (including data from four primate species), males exhibited higher prevalence than females (Fig. 3.11). On the other hand, studies focusing on ectoparasites and intestinal helminths in wild primates have failed to show consistent sex differences in prevalence (Table 3.6). Among primate studies that documented a significant sex difference, some authors

Perissodactyla (4) j

Chiroptera (11) h|h Lagomorpha (11) Rodentia*(94) Artiodactyla (90) MAMMALIA*(300) Carnivora*(104) Sirenia*(5) Marsupialia (16) Primata (7) Insectivora (7)

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