Wild primate populations, an unexplored source of information regarding emerging infectious disease, may hold valuable clues to the origins and evolution of some important pathogens. Primates can act as reservoirs for human pathogens. As members of biologically diverse habitats, they serve as sentinels for surveillance of emerging pathogens and provide models for basic research on natural transmission dynamics. Since emerging infectious diseases also pose serious threats to endangered and threatened primate species, studies of these diseases in primate populations can benefit conservation efforts and may provide the missing link between laboratory studies and the well-recognized needs of early disease detection, identification, and surveillance.

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Wild primate populations in emerging infectious disease research: the missing link?

EIAs for IgG and IgM antibodies directed against Ebola (EBO) viral antigens have been developed and evaluated using sera of animals and humans surviving infection with EBO viruses. The IgM capture assay detected anti-EBO (subtype Reston) antibodies in the sera of 5 of 5 experimentally infected animals at the time they succumbed to lethal infections. IgM antibodies were also detected in the serum of a human who was infected with EBO (subtype Reston) during a postmortem examination of an infected monkey. The antibody was detectable as early as day 6 after infection in experimentally infected animals and persisted for o90 days. The IgG response was less rapid; however, it persisted for u400 days in 3 animals who survived infection, and it persisted for C10 years after infection in the sera of 2 humans. Although these data are limited by the number of sera available for verification, the IgM assay seems to have great promise as a diagnostic tool. Furthermore the long-term persistence of the IgG antibodies measured by this test strongly suggests that the ELISA will be useful in field investigations of EBO virus.

https://www.jstor.org/stable/info/30117622

ELISA for the Detection of Antibodies to Ebola Viruses

Leishmaniasis affects approximately 2 million people each year throughout the world. This high incidence is due in part to the lack of an efficacious vaccine. We present evidence that the recombinant leishmanial antigens LmSTI1 and TSA, which we identified and characterized previously, induce excellent protection in both murine and nonhuman primate (rhesus monkey) models of human cutaneous leishmaniasis. The remarkable protection induced by LmSTI1 and TSA in an animal model that is evolutionarily close to humans qualifies this antigen combination as a promising candidate subunit vaccine against human leishmaniasis.

Protection against cutaneous leishmaniasis induced by recombinant antigens in murine and nonhuman primate models of the human disease.

Three troops of olive baboons (Papio anubis) comprising 134 animals were captured during a translocation program. All three troops (PHG, CRIP, WBY) lived in high-altitude savannah, but two (CRIP and WBY) also frequented human settlements, where they had access to the garbage pits and vegetable gardens. The translocation offered the opportunity to compare body condition, activity patterns, and parasitism among the troops of animals. A variety of body measurements were taken, a physical examination performed, activity patterns for the previous 2 years enumerated, and blood and feces collected for virological and parasitological analyses. Body condition, as judged qualitatively by appearance and quantitatively by subcutaneous fat thickness and body weight, was lowest in PHG, the naturally foraging troop. All animals were negative for all viruses. No blood-borne parasites were found, but the feces of the majority of animals were positive for eggs of strongyles, ascarids, Trichuris spp., and Strongyloides spp. Quantification of strongyles indicated the heaviest burdens were in the non provisioned troop PHG. These results when combined with the behavioral observations that PHG spent more time foraging and less time resting or socializing than WBY suggest lowered availability and/or a poorer quality of PHG's diet. The data support the hypothesis of a causal relationship between host nutrition and helminth parasite infection but do not permit general conclusions to be drawn on mechanisms of interaction.

Nutrition, body condition, activity patterns, and parasitism of free‐ranging troops of olive baboons (Papio anubis) in Kenya

In public health terms, leishmaniases are diseases of humans and dogs, whereas, in epidemiological terms, Leishmania spp. are considered to represent infections of a wide variety of animals, which represent the natural reservoirs of the various parasite species involved. Humans and dogs (which may be considered secondary or 'accidental' hosts in the leishmanial life-cycle) often exhibit severe clinical signs and symptoms when infected, whereas reservoir hosts generally show a few, minor or no signs. This situation makes the definition of a suitable laboratory model a difficult one, since the various experimental hosts may behave either like a reservoir or an accidental host. This review discusses the concept of animal models for leishmaniases and provides a critical evaluation of the most common experimental models and their respective advantages and disadvantages. In this state-of-the-art review, particular emphasis is given to the value of using mouse, hamster, cotton-rat, dog and primate models, especially in the context of testing potential anti-leishmanial vaccines.

Experimental models for leishmaniasis and for testing anti-leishmanial vaccines.

Sera from 464 primates held at four institutes in Kenya were tested by indirect immunofluorescence for the presence of antibodies against Marburg, Ebola, Congo haemorrhagic fever, Rift Valley fever and Lassa viruses. Four of 136 vervet monkeys were positive for Marburg virus antibodies and three of 184 baboons had antibodies against Ebola virus. One baboon was positive for Marburg virus antibodies. Two vervet monkeys, three baboons and one grivet monkey (of 56 tested) had antibodies against Rift Valley fever virus. No Congo or Lassa virus antibodies were detected. A sample of 88 sera of more arboreal primates (Sykes, blue and colobus monkeys) were negative against all five antigens, as were sera from 58 staff members of the institutes who worked with or near the animals.

Marburg, Ebola and Rift Valley fever virus antibodies in East African primates

The susceptibility of four East African primate species to experimental infection with Leishmania donovani was investigated. Vervet monkeys (Cercopithecus aethiops), Sykes monkeys (C. mitis) and baboons (Papio cynocephalus) all supported low grade infections for periods ranging between four and eight months and subsequently showed evidence of self-cure. Greater bushbabies (Galago crassicaudatus) remained completely refractory throughout the course of the experiment. The significance of hepatic histiocytic nodules in the infected primates, similar to those observed in asymptomatic human visceral leishmaniasis, and the susceptibility of Old World primates to experimental infection are discussed.

The suitability of East African primates as animal models of visceral leishmaniasis.

Marburg and ebola virus antibodies in kenyan primates

In the latter part of 1982, three black and white colobus monkeys, Colobus abyssinicus kikuyuensis, from a small breeding group maintained at the Institute of Primate Research in Kenya, became paralysed within one month. Two of these cases were fatal and the third animal survived. The clinical and pathological findings suggested a poliomyelitis-like disease. This was confirmed by the isolation of wild strains of poliomyelitis virus type I from faeces, spleen, kidney, lung and central nervous system from affected animals.

J.G. Else

Papers

Marburg, Ebola and Rift Valley fever virus antibodies in East African primates

The suitability of East African primates as animal models of visceral leishmaniasis.

Marburg and ebola virus antibodies in kenyan primates

An outbreak of poliomyelitis caused by poliovirus type I in captive black and white colobus monkeys (Colobus abyssinicus kikuyuensis) in Kenya.