African Snake Research Articles

Consequences of neglect: analysis of the sub-Saharan African snake antivenom market and the global context.

BackgroundThe worldwide neglect of immunotherapeutic products for the treatment of snakebite has resulted in a critical paucity of effective, safe and affordable therapy in many Third World countries, particularly in Africa. Snakebite ranks high among the most neglected global health problems, with thousands of untreated victims dying or becoming permanently maimed in developing countries each year because of a lack of antivenom—a treatment that is widely available in most developed countries. This paper analyses the current status of antivenom production for sub-Saharan African countries and provides a snapshot of the global situation.MethodsA global survey of snake antivenom products was undertaken in 2007, involving 46 current and former antivenom manufacturers. Companies producing antivenom for use in sub-Saharan Africa were re-surveyed in 2010 and 2011.ResultsThe amount of antivenom manufactured for sub-Saharan Africa increased between 2007 and 2010/11, however output and procurement remained far below that required to treat the estimated 300,000–500,000 snakebite victims each year. Variable potency and inappropriate marketing of some antivenoms mean that the number of effective treatments available may be as low as 2.5% of projected needs. Five companies currently market antivenom for sale in Africa; three others have products in the final stages of development; and since 2007 one has ceased production indefinitely. Most current antivenom producers possess a willingness and capacity to raise output. However inconsistent market demand, unpredictable financial investment and inadequate quality control discourage further production and threaten the viability of the antivenom industry.ConclusionFinancial stimulus is urgently needed to identify and develop dependable sources of high-grade antivenoms, support current and emerging manufacturers, and capitalise on existing unutilised production capacity. Investing to ensure a consistent and sustainable marketplace for efficacious antivenom products will drive improvements in quality, output and availability, and save thousands of lives each year.

Population Density and Survival Estimates of the African Viperid, Bitis schneideri

Although estimates of survival and population density are available for several snake populations, most of these are for populations in northern temperate environments. Here we present the results of a 3-yr mark–recapture study for an African species, the Namaqua Dwarf Adder (Bitis schneideri). We estimated survival, recapture probability, and population density by marking 279 adders (121 males, 108 females, 50 juveniles) on two study sites along the Namaqualand coast of South Africa. We recaptured 54 individuals (27 males, 23 females, 4 juveniles), yielding absolute recapture rates of 20.4% and 17.9% at each site respectively. The adult sex ratio of our sample did not differ significantly from equality. We fitted eight models that included both individual-dependent and time-dependent covariates to our recapture data, and compared models using Akaike information criterion corrected for small samples. The best models included snout–vent length and search effort covariates. Mean (±SD) estimated monthly apparent survival was low (0.86 ± 0.11 and 0.86 ± 0.12), as were mean recapture likelihoods (0.06 ± 0.04 and 0.06 ± 0.01). Population density estimates were similar for the two sites (7.52 ± 3.62 ha−1 and 8.31 ± 7.38 ha−1). Juvenile snakes exhibited higher survival than adult females, which, in turn, had higher survival than adult males. Juveniles had a lower recapture probability than adult males or females. The likelihood of an individual leaving the study area was 6.8% and 9.4% per month for the larger and smaller sites, respectively. On the basis of our measures of apparent survival and emigration, we estimate annual survival rates of 39% and 56% for the two sites respectively. Population characteristics of B. schneideri differ substantially from those of other viperids, highlighting the need for additional population studies of African snakes.

Assimilation efficiency and gut passage time in an African elapid snake, Hemachatus haemachatus

We measured apparent assimilation efficiency (AAE) and gut passage time in the African elapid snake Hemachatus haemachatus under laboratory conditions. AAE was dependent on food type, being 89.8% when snakes were fed frogs and 82.8% when fed mice. Differences in AAE for different meal types could be ascribed to the indigestible hair in mouse meals because differences were lost once this component of the mouse meals was removed from the calculation. AAE did not depend on snake body mass and there was no significant difference between AAE measures made at 20°C and 27°C for mouse meals. Gut passage time was 25% faster at 27°C than at 20°C, but was not affected by food type or snake body mass. Larger meals took longer to digest. Thus, H. haemachatus appears to offset reduced digestive performance at lower temperatures by retaining food in the gut for longer when at lower body temperatures (Tbs). These results fit an emerging pattern in snakes whereby digestive efficiency is generally high and insensitive to Tb over the selected thermal range, but may become dependent at lower Tbs when digestion is eventually arrested. The rate of digestion is highly temperature-sensitive and is fastest in the selected Tb range. Diet appears to affect digestive efficiency owing, mainly, to the presence of indigestible components such as hair. Using a comparative framework, venom does not appear to improve digestion for this species, at least over the temperature range tested, relative to other snake species in the literature.

To run or hide?: escape behaviour in a cryptic African snake

Optimal escape theory predicts that escape behaviour of an organism is best understood in terms of costs and benefits of escaping relative to risk of predation. However, risk of predation facing an organism is dependent on various biotic and abiotic factors. In order to better understand escape behaviour of an African snake, the Namaqua dwarf adder (Bitis schneideri), I simulated predatory attacks on 51 free-ranging snakes, quantifying whether or not they fled. Additionally I measured body size, sex, body condition, and the surface temperature of the location of each snake, as well as the situation (buried or active on the surface) of the snake. I used generalized logistic regression to assess which variables predicted whether the snake fled during/following the simulated attack or not. Surface temperature was significantly associated with a flight-response, with warmer snakes more likely to flee than cooler snakes. Buried snakes were less likely to flee than snakes that were active on the surface. These findings generally support optimal escape theory in that both factors are strongly linked to risk of predation: temperature is likely to influence sprint performance, while situation is likely to influence the detectability of the snake to predators.

Ophiotaenia lapata sp n. (Eucestoda: Proteocephalidea) from Madagascar: a parasite of the endemic snake Madagascarophis colubrinus (Colubridae)

Ophiotaenia lapata sp. n. (Cestoda: Proteocephalidea) from Madagascar: a parasite of the endemic snake Madagascarophis colu - brinus (Colubridae). - a new proteocephal idean cestode, Ophiotaenia lapata sp. n., is described from the gut of the endemic col ubrid snake Madagascarophis colubrinus (schl egel , 1837) (Col ubridae) from madagascar. The new species differs from al l but one Ophiotaenia species parasitic in african snakes by the presence of an apical organ. Ophiotaenia lapata differs from O. adiposa Rudin, 1917, which al so possesses an apical organ, by the number of testes (89-170 in the new species versus 170-220 in O. adiposa ), by the position of the genital pore in rel ation to the anterior margin (43-53% of progl ottis l ength in O. lapata versus 20-25%) and the scol ex width (240-280 µ m in the former species versus 500-600 µ m in the l atter). The new species possesses, unl ike al l but one Ophiotaenia species parasitic in african snakes, a three-l ay ered embry ophore. The other african species have two-l ay ered embry ophore ex cept for Ophiotaenia georgievi de Chambrier, ammann & schol z , 2010, which can be distinguished by the absence of an apical organ, by the number of uterine branches on each side (23-28 in O. georgievi versus 41-68 in O. lapata ) and by the total l ength of the strobil a (50 mm in O. georgievi and 295 mm in O. lapata ). Ophiotaenia lapata is the third proteocephal idean cestode reported from madagascar.

A developmental staging series for the African house snake, Boaedon (Lamprophis) fuliginosus

Embryonic staging series are important tools in the study of morphological evolution as they establish a common standard for future studies. In this study, we describe the in ovo embryological development of the African house snake (Boaedon fuliginosus), a non-venomous, egg-laying species within the superfamily Elapoidea. We develop our staging series based on external morphology of the embryo including the head, eye, facial prominences, pharyngeal slits, heart, scales, and endolymphatic ducts. An analysis of embryonic growth in length and mass is presented, as well as preliminary data on craniofacial skeletal development. Our results indicate that B. fuliginosus embryos are well into organogenesis but lack well-defined facial prominences at the time of oviposition. Mandibular and maxillary processes extend rostrally within 8 days (stage 3), corresponding to the first appearance of Meckel's cartilages. Overall, the development of the craniofacial skeleton in B. fuliginosus appears similar to that of other snake species with intramembraneous bones (e.g., dentary and compound bones) ossifying before most of the endochondral bones, the first of which to ossify are the quadrate and the otic capsule. Our staging series is the first to describe the post-ovipositional development of a non-venomous elapoid based on external morphology. This species is an extremely tractable captive that can produce large clutches of eggs every 45 days throughout the year. As such, B. fuliginosus should be a good model for evolutionary developmental biologists focusing on the craniofacial skeleton, loss of limbs, generational teeth, and venom delivery systems.

Premature sperm ejaculation in captive African brown house snake Lamprophis fuliginosus

Many ophidians exhibit prolonged copulation, a behaviour hypothesised to be the result of a slow and gradual ejaculation process or a behaviour aimed toward reducing sperm competition (male mate guarding). While observing courtship behaviour in a captive colony of the African brown house snake, Lamprophis fuliginosus, some males excreted a large amount of sperm very rapidly before the inflation and insertion of the males’ hemipenis into the females’ vent. This observation of premature ejaculation suggests that male snakes may be capable of rapid ejaculation and, therefore, likely copulate for an extended period of time to prevent rival males from mating with the same female, thus increasing the chance of paternity for the male.

The type species of the threadsnake genus Tricheilostoma Jan revisited (Squamata, Leptotyphlopidae)

For most of the last 150 years, Tricheilostoma Jan, 1860 has resided in the synonymy of other snake genera such as Glauconia Gray, 1845 and Leptotyphlops Fitzinger, 1843 (Boulenger, 1893; McDiarmid et al., 1999). Thus there has been less practical concern over the identity of the type species. This changed recently with the proposal of a new classification of the family Leptotyphlopidae and resurrection of the Genus Tricheilostoma (Adalsteinsson et al., 2009). Pinto et al. (2010) alluded to a potential taxonomic problem with the type species of that genus, but determined that no change was necessary. However, the problem remains and affects 15 species of South American and African snakes. The purpose of this note is to resolve the issue and make the necessary taxonomic changes.

Reproductive biology, length-weight relationship and condition factor of the African snake head, Parachanna obscura , from River Oshun, South-west Nigeria

Aspects of the biology of the African snake head, Parachanna obscura, obtained from River Oshun, South-west Nigeria, from August 2006 to February 2007, were studied. Fish were captured with gill nets. The species attained a maximum total length of 36.4 cm and body weight of 389.36 g. The length/weight relationship indicated allometric growth for males and isometric growth for females. Gonado-somatic index ranged between 1.1 and 2.8% in the females. Values of condition factor were high for males. There were more females than males, and immature fish dominated the catch. Eggs ranged in size between 0.88 and 1.11 mm, while fecundity estimates ranged between 1711 and 4000 and were not related to length and body weight. P. obscura in this study did not show any distinct seasonal pattern of breeding. Key words: Parachanna obscura, River Oshun, Nigeria, reproductive biology.

The energetic cost of pregnancy compared to digestion and exhaustive exercise in the oviparous African Brown House Snake

The energetic cost of pregnancy compared to digestion and exhaustive exercise in the oviparous African Brown House Snake

Molecular systematics of the African snake family Lamprophiidae Fitzinger, 1843 (Serpentes: Elapoidea), with particular focus on the genera Lamprophis Fitzinger 1843 and Mehelya Csiki 1903

The snake family Lamprophiidae Fitzinger (Serpentes: Elapoidea) is a putatively Late Eocene radiation of nocturnal snakes endemic to the African continent. It incorporates many of the most characteristic and prolific of Africa’s non-venomous snake species, including the widespread type genus Lamprophis Fitzinger, 1843 (house snakes). We used approximately 2500 bases of mitochondrial and nuclear DNA sequence data from 28 (41%) of the approximately 68 recognised lamprophiid species in nine of the eleven genera to investigate phylogenetic structure in the family and to inform taxonomy at the generic level. Cytochrome b, ND4 and tRNA gene sequences (mitochondrial) and c-mos sequences (nuclear) were analysed using Maximum Likelihood, Bayesian Inference and Maximum Parsimony methods. The genus Mehelya Csiki, 1903 was paraphyletic with respect to Gonionotophis Boulenger, 1893. To address this, the concept of Gonionotophis is expanded to include all current Mehelya species. The genus Lamprophis emerged polyphyletic: the enigmatic Lamprophis swazicus was sister to Hormonotus modestus from West Africa, and not closely related to its nominal congeners. It is moved to a new monotypic genus (Inyoka gen. nov.). The remaining Lamprophis species occur in three early-diverging lineages. (1) Lamprophis virgatus and the widely distributed Lamprophis fuliginosus species complex (which also includes Lamprophis lineatus and Lamprophis olivaceus) formed a clade for which the generic name Boaedon Duméril, Bibron & Duméril, 1854 is resurrected. (2) The water snakes (Lycodonomorphus) were nested within Lamprophis (sensu lato), sister to Lamprophis inornatus. We transfer this species to the genus Lycodonomorphus Fitzinger, 1843. (3) We restrict Lamprophis (sensu strictissimo) to a small clade of four species endemic to southern Africa: the type species of Lamprophis Fitzinger, 1843 (Lamprophis aurora) plus Lamprophis fiskii, Lamprophis fuscus and Lamprophis guttatus.

First species of Ophiotaenia (Cestoda: Proteocephalidea) from Madagascar: O. georgievi sp. n., a parasite of the endemic snake Leioheterodon geayi (Colubridae)

Ophiotaenia georgievi sp. n. (Proteocephalidea: Proteocephalinae) is described from the intestine of endemic colubrid snake Leioheterodon geayi Mocquard (Colubridae) from Antananarivo in Madagascar. The new species is the first species of Ophiotaenia La Rue, 1911 reported from Madagascar. It differs from all Ophiotaenia species parasitic in African snakes in the possession of a three-layered embryophore of eggs (other African species have two-layered embryophore). Furthermore, O. georgievi can be distinguished by the number of testes (92-140), width of the scolex (225-235 jm), total body length (57 mm), cirrus-sac length/proglottis width ratio (19-32%), and number of lateral uterine diverticula (23-28 on each side). Ophiotaenia georgievi represents the second proteocephalidean cestode reported from Madagascar, the first one being Deblocktaenia ventosaloculata (Deblock, Rosé et Broussart, 1962), a parasite from Ithycyphus miniatus. A list of Ophiotaenia species parasitic in venomous and non-venomous snakes is provided and possible existence of other new congeneric species in snakes from Madagascar is discussed.

First reported case of African viper bite treated with Indian polyvalent anti snake venom

Dear Editor, The compositional differences between venoms among different geographic regions may be due to evolutionary environmental pressure acting on isolated populations. The polyvalent variety of anti snake venom (ASV) with local specificity remains the mainstay of therapy in most countries. ASV against the venom of one species occasionally may have partial cross neutralizing activity against other venoms, usually from closely related species, known as paraspecific activity. We managed a case of an African viper bite successfully using Indian polyvalent ASV as the specific African variety was not available to us. A 25 year old serving soldier of a foreign army contingent in UN mission in the Democratic Republic of Congo, was brought on 29 Sep 07 at 0025 hours, with a history of a mildly painful snake bite of about two hours duration on the left foot. There was no history suggestive of neurological involvement. Clinical examination revealed normal vital parameters and a normal general examination. Local exam revealed swelling and tenderness of left foot extending beyond the ankle to the distal leg. Two fang marks 1.5 cm apart were visible on dorsum of left foot along with a small patch of ecchymosis (Fig. 1). Fig. 1 Fang marks with swelling of foot. A bed side whole blood clotting time revealed no clotting at 30 minutes, with a clotting time of 35 minutes by capillary method. Bleeding time was in normal range. Since specific ASV for the regional area was not available, a decision to give Indian polyvalent ASV (which was available) was taken as an emergency life saving measure. A total of 150 ml of reconstituted ASV (15 vials of polyvalent Indian variety) was administered as per standard protocol over next nine hours in view of progressively increasing swelling in the leg and deranged clotting time in range of 15 to 21 minutes. The progression of the swelling of the limb halted and clotting parameters started improving (Fig. 2). Antibiotics and other supportive therapy were given. The patient had a haemoglobin drop from 16.3 to 13.6 gm per dl and mild thrombocytopenia in range of 1,20,000 to 1,40,000/mm2 during the initial few days which subsequently recovered. He also developed an uncomplicated resolving small abdominal wall hematoma (confirmed by ultrasound). He was discharged at three weeks with a complete and uneventful recovery. Fig. 2 Reduction of swelling of the limb by day three. The mortality after untreated viper bites like Crotalus durissus terrificus is said to have been up to 70 %, but this has been reduced to less than 12% by ASV treatment and in African varieties like Atractaspis and bush vipers (like those found in the Congo basin) the mortality ranges from 8-43% [1, 2]. “Specific” antivenom, implies that the antivenom has been raised against the venom of a particular snake that has bitten the patient (Monovalent or monospecific antivenom). Polyvalent antivenom neutralises the venoms of several different species of snakes. FAV AFRICA is the polyvalent equine ASV recommended for Sub-Saharan African snakes. The Indian ASV contains sera against the saw scaled viper, Russel's viper. Indian Cobra (Naja naja) and the banded krait. Analysis of Indian cobra (Naja naja) venom samples from eastern, western and southern India revealed differences in composition, biochemical, and pharmacological properties emphasizing regional variation: continents will logically be different [3]. There are only a handful of documented cases of snake bites managed with ASV pertaining to different geographical locations. Use of Tiger Snake ASV in Stephen's Banded Snake envenomation in Australia, pit viper envenomation (South American) treated with nonspecific ASV and two North American coral snake venoms treated with Mexican ASV have been described [4, 5, 6]. A study was performed to assess the ability of polyvalent anti snake venom VACSERA (produced by Egypt), to neutralize venoms of snakes not only from Egypt but also African and Middle Eastern habitats showed encouraging results [7]. There is a description of a severe systemic envenomation of a African bush viper managed successfully with Near Middle East ASV [8]. Ours is possibly the first reported case of an African viper bite successfully managed with Indian polyvalent ASV given in the backdrop of unavailability of specific antisera. We recommend that more studies be carried out on this paraspecific activity of the Indian ASV.

A quantitative analysis of two scale characters in snakes

AbstractWe quantified the effectiveness of two scale characters commonly used to identify snakes: smooth versus keeled dorsal scales and straight versus oblique dorsal scale rows. We examined 169 species of African snakes from close-up photographs of the dorsal scales. We calculated the prominence of keels (if present) along the dorsal scales and the degree of straightness or obliqueness of the dorsal scale rows. We compared our measurements to species descriptions from the literature and looked for overlap of the character states with each other. Our results show a distinct difference between keel prominence for species described as having keeled dorsal scales versus species described as having smooth dorsal scales. Our results also show considerable overlap of straightness or obliqueness between species described as having straight dorsal scale rows versus those described as having oblique dorsal scale rows. Revision of this character would be beneficial.

Inhibitory effects of sub-optimal root zone temperature on leaf bioactive components, photosystem II (PS II) and minerals uptake in Trichosanthes cucumerina L. Cucurbitaceae

We hypothesized that sub-optimal root zone temperature (RZT) will cause a reduction in the bioactive components contents, adversely affect PS II and hinder uptake/partitioning of mineral elements in the “Light Green Variant” of the African snake tomato (Trichosanthes cucumerina L.). Three RZT temperatures (20, 25 and 30°C) were evaluated in a digitally controlled growth chamber. Results showed that for all the mineral nutrients analyzed (Ca, Mg, P, K, Fe and Mn), the amounts absorbed by the plant increase as RZT increases with each nutrient displaying different characteristics with respect to the quantity partitioned into root, stem and leaf at the different RZT. At sub-optimal RZT (20°C), significantly higher amounts of Ca and K were found in the root, whereas at normal RZT (25 and 30°C) higher amounts of Ca were recorded in the stem, and about 50% of the amounts in the stem were found in the leaves. For all the RZT, the amounts of Mg in the leaves were significantly higher than in the root and stem, while the amounts in the stems were also significantly higher than the amounts in the roots. At normal RZT (25 and 30°C) almost equal amounts of P were present in the root, stem and leaf. The amounts of phenolics, ascorbic acid, chlorophyll a and b and total chlorophyll increase as the RZT increases. Photosystem analyses showed that at 30°C the Fv/Fm (relative photochemical efficiency) was 0.76, while at 20 and 25°C the values were 0.35 and 0.60, respectively. The Fv/Fm value (0.35) obtained at 20°C confirmed the adverse effects of sub-optimal RZT on the photosystem II (PS II). Photosynthetic measurements showed that as the RZT increased, A (net photosynthetic efficiency), E (transpiration rate), Ci (intercellular carbon dioxide concentration) and g1 (stomata conductance) also increased. We postulate that the higher E and g1 at high RZT have a great physiological implication on plant performance, because transpiration cooling would be improved, especially during the summer; but the lost water must be complemented by adequate irrigation. The totality of the results confirm our hypothesis that sub-optimal RZT will cause a reduction in the bioactive components contents, adversely affect PS II and hinder uptake/partitioning of mineral elements in T. cucumerina.

Embryonic jaw development in Lamprophis fuliginosus (African house snake)

Embryonic jaw development in Lamprophis fuliginosus (African house snake)

Vertical posturing, defensive strikes, and leaping in African elapid snakes

Vertical posturing, defensive strikes, and leaping in African elapid snakes

Modeling the Effects of Anthropogenic Habitat Change on Savanna Snake Invasions into African Rainforest

We used a species-distribution modeling approach, ground-based climate data sets, and newly available remote-sensing data on vegetation from the MODIS and Quick Scatterometer sensors to investigate the combined effects of human-caused habitat alterations and climate on potential invasions of rainforest by 3 savanna snake species in Cameroon, Central Africa: the night adder (Causus maculatus), olympic lined snake (Dromophis lineatus), and African house snake (Lamprophis fuliginosus). Models with contemporary climate variables and localities from native savanna habitats showed that the current climate in undisturbed rainforest was unsuitable for any of the snake species due to high precipitation. Limited availability of thermally suitable nest sites and mismatches between important life-history events and prey availability are a likely explanation for the predicted exclusion from undisturbed rainforest. Models with only MODIS-derived vegetation variables and savanna localities predicted invasion in disturbed areas within the rainforest zone, which suggests that human removal of forest cover creates suitable microhabitats that facilitate invasions into rainforest. Models with a combination of contemporary climate, MODIS- and Quick Scatterometer-derived vegetation variables, and forest and savanna localities predicted extensive invasion into rainforest caused by rainforest loss. In contrast, a projection of the present-day species-climate envelope on future climate suggested a reduction in invasion potential within the rainforest zone as a consequence of predicted increases in precipitation. These results emphasize that the combined responses of deforestation and climate change will likely be complex in tropical rainforest systems.

Life in the tropical suburbs: Food type partitioning among sympatric African house snakes of the genus Lamprophis (Colubridae)

The food niche partitioning of four species of house snakes (Lamprophis fuliginosus, L. olivaceus, L. lineatus, and L. virgatus) was studied in suburban areas of south‐eastern Nigeria, West Africa. Snakes were captured in the field, and their stomach contents were obtained by forced‐squeezing of the ingested bolus. Pseudo‐community analysis and Monte Carlo simulations, by two different algorithms, were used to investigate whether the community under study was randomly assembled along the trophic niche axis. Four hundred and thirty snake individuals were captured: 52 out of 133 L. fuliginosus (32.1%), 31 of 126 (24.6%) L. lineatus, 30 of 108 (27.8%) L. virgatus, and 20 of 63 (31.7%) L. olivaceus had identifiable food contents in the stomach. Lamprophis fuliginosus appeared as the more generalist species, L. lineatus showed some preference for lizards and frogs, L. virgatus for small mammals (rodents and shrews), and L. olivaceus for nestling birds and small mammals. However, null models showed that the community organization was random along the food niche axis by both the randomization algorithms used in this paper. Thus, we concluded that these four snake species do not partition either the quality or the number of the available resources.

Characterization of a new polyvalent antivenom (Antivipmyn ® Africa) against African vipers and elapids

As a response to the antivenom shortage in Sub-Saharan Africa, evident for well over a decade, we developed a new polyvalent anti-ophidian antivenom (Antivipmyn ® Africa) designed for use in the region. We report a detailed characterization of its biochemical composition (protein content and profiling by size-exclusion chromatography and electrophoresis) as well as the specific and para-specific neutralization potencies (as median effective dose in the mouse lethality test). Additionally, we studied the neutralization of hemorrhagic, anti-hemostatic and necrotic activities of Echis ocellatus venom, responsible for a majority of severe envenomations in the continent according to existing epidemiological data. The antivenom is currently under production and has already been employed in the field in a pragmatic Phase III clinical trial in the Republic of Benin. It is a purified lyophilized polyvalent equine F(ab′) 2-based product obtained by immunization with the venoms of eleven species of African snakes of the Genera Echis, Bitis, Naja and Dendroaspis. The criteria for its design are discussed, particularly in terms of the implementation of realistic public health policies targeting mostly rural populations in the continent.